JP6386330B2 - Repair method for defective welds in metal cask welded structures - Google Patents

Description

The present invention relates to a weld defect portion repair how metal cask welded structure, in particular, to transport or storage or transport and storage of spent fuel generated from nuclear power plants, etc., and the steel of the inner cylinder and the outer cylinder copper heat transfer fins about the weld defect portion repair how suitable metal cask welded structures to those welded directly.

  In general, a plurality of fuels used for a certain period in a nuclear power plant nuclear reactor are taken out of the nuclear reactor and temporarily stored in a spent fuel cooling pool or the like. Spent fuel that has been cooled in the spent fuel cooling pool for a specified period of time is stored in a radioactive material storage container called a metal cask to be used as a resource, and then transported to an intermediate storage facility until it is reprocessed at the reprocessing facility. Stored.

  A metal cask that transports and stores spent fuel assemblies consists of an inner cylinder (also called an inner cylinder container, a container body, or a trunk body) that stores spent fuel, and an outer cylinder and an inner cylinder that absorb impact from the outside. It has a plurality of lids to be sealed.

  Since spent fuel contains a high level of radioactive material, it generates decay heat, so the decay heat generated from the spent fuel assembly is transferred between the inner and outer cylinders between the inner and outer cylinders. A plurality of heat transfer fins are provided for escape to the outside of the cylinder, and the plurality of heat transfer fins are welded to the inner cylinder and the outer cylinder, respectively.

  Usually, carbon steel materials and stainless steel materials with good performance such as rigidity and shielding properties are used as the material of the inner cylinder and the outer cylinder, while copper materials with good heat conduction are mainly used as the material of the heat transfer fins. Moreover, the copper clad steel material etc. which joined two types of metals previously are also used.

  The technique which welds a heat-transfer fin to the outer surface of the inner cylinder of the metal cask mentioned above and the inner surface of an outer cylinder is disclosed by patent documents 1 thru | or 5, for example. In addition, although it is not a metal cask, it repairs and welds defects that occur in the vicinity of welds between the cladding of the reactor pressure vessel and the internal structure, as well as repairing defects in the friction stir welds of vehicle structures. Patent Documents 6 to 8 disclose a method and repair welding by arc welding while following a crack.

  Patent Document 1 describes a method for manufacturing a metal container. A welding process for generating a MIG arc from a pure copper MIG wire, and a plasma arc from a plasma electrode arranged coaxially so as to surround the MIG arc are generated. The plasma welding process is performed in parallel. In the MIG welding process and the plasma welding process, the angle between the copper heat transfer fin and the horizontal plane is 15 to 20 degrees, and the angle between the heat transfer fin and the carbon steel inner cylinder is It is disclosed that the MIG arc and the plasma arc are generated downward by arranging them at 75 degrees or more.

  Patent Document 2 describes a composite welding method and a welding torch for composite welding, in which a TIG arc is generated on the leading side and a MIG arc is generated on the trailing side and welding is performed. It is disclosed that the current is set to be larger than the current, an arc is continuously generated at the TIG electrode and the MIG electrode, and the distance between both arcs is set to 20 mm or less. Furthermore, it is disclosed that a mixed gas of Ar gas and H2 gas, a mixed gas of Ar gas and He gas, and a mixed gas of Ar + H2 + He is used as the shielding gas.

  Patent Document 3 describes a metal cask for a radioactive substance, and includes a heat transfer fin that extends radially outward from a trunk body and transfers heat to an outer cylinder. The heat transfer fin joins two types of metal plates. And one metal of the clad material is made of the same metal material for the trunk body and the outer cylinder, and the other is made of a good heat transfer material with good heat conduction, and the trunk body (and / or It is disclosed that an outer tube) and a clad region of the same metal are directly welded.

  Patent Document 4 describes a welding method, a welding process of welding a steel base material and a copper base material requiring heat treatment after welding by a welding means such as a MIG torch, and the welding means and a predetermined distance. The welding heat-affected zone of the steel base metal is heated (including melting) on the welding bead generated in the welding process by a heating means such as an arc welding torch, a high-frequency coil, or a laser arranged at a rearward position. And before the welding process, by a heating means such as a TIG torch, a YAG laser, or a high-frequency coil arranged at a front position ahead of the welding means by a predetermined distance before the welding process. Discloses preheating a copper base material having high thermal conductivity.

  Patent Document 5 describes a radioactive substance storage container, and parallel portions are formed at both ends of the copper heat transfer fins, and the parallel portions are formed along the outer peripheral surface of the container main body and the inner peripheral surface of the outer cylinder. It is disclosed that the outer peripheral surface of the container body and the inner peripheral surface of the outer cylinder and the parallel tip portions of the heat transfer fins are welded by MIG welding or MIG brazing using a copper alloy wire.

  Further, Patent Document 6 describes a method for repairing a friction stir welded portion, and includes a step of grinding and removing defects contained in a weld bead formed by friction stir welding to form a repair region, and a base material (aluminum for a joint member). And a step of forming a repair bead by TIG welding using a welding rod of the same material.

  On the other hand, Patent Document 7 describes a method for repairing a reactor pressure vessel. When a defective portion including a welded portion and a clad portion is mechanically cut out and removed, the remaining thickness of the clad is less than 3.2 mm. It is disclosed that the removed portion is repaired by overlay welding using a temper bead method, and when the remaining thickness of the clad is 3.2 mm or more, the removed portion is repaired by ordinary overlay welding.

  Patent Document 8 describes a crack repair method. When performing crack repair welding in a lateral orientation, a surveillance camera that images a crack portion of a structural member and a welding head are driven and controlled, and the crack portion is tracked. Using a crack repair welding device equipped with a welding control means, a flux-cored wire containing metal oxide is inserted from above the molten pool in a direction perpendicular to the welding progress direction from the wire supply nozzle, and the crack is removed without removing the crack. It is disclosed that repair welding is performed by arc welding (TIG welding) while following.

JP 2009-178727 A JP 2013-158826 A JP 2007-205931 A JP 2002-361469 A JP 2008-82906 A JP 2002-59289 A JP 2000-275384 A Japanese Patent Laid-Open No. 2005-21953

  However, in Patent Document 1 described above, since the MIG arc and the plasma arc are generated almost coaxially, the electromagnetic forces acting on both arcs cancel each other, but the MIG wire (consumable electrode) and the plasma electrode (non-consumable) Since the polarity of the electrode is positive (plus) and the base metal side is negative (minus), the plasma electrode is easily consumed and damaged, so long members with long weld lines that require long-term operation It is not suitable for welding, and if the plasma electrode is consumed during welding, it may change to unstable arc behavior and adversely affect weld bead formation, leading to poor welding. Pure copper is a material with high thermal conductivity, but the dissimilar welding of copper and steel has poor compatibility and is difficult to dissolve. Therefore, pure copper MIG wire is used to connect copper and steel joints. If the penetration on the steel side becomes deeper after welding, weld cracks (solidification cracks) are likely to occur. Further, Patent Document 1 does not apply to the use of SiCu wires, the occurrence of welding defects (or defective welding), and repair welding of defective welding parts, and there is no description at all. There is no suggestion.

  Further, in Patent Document 2, it is considered that the rigidity and stability of the arc are improved by welding with the TIG current larger than the MIG current and the distance between both arcs set to 20 mm or less. When the distance between the arcs is long, the molten pool formed by the two arcs that are separated from each other has an elongated and unstable shape, and tends to have an uneven bead shape (meandering bead). Further, although it is described that He gas or a mixed gas of H2 gas and Ar gas is used, in the verification test, a welding result using only Ar gas is described. In the verification test, a welding result using a stainless steel base material is described. Although the material of the welding wire used for this welding is not described, it is presumed that it will be a stainless steel welding wire similar to the base material. For this reason, as in the case of Patent Document 1, in Patent Document 2, the use of a SiCu wire, welding of a dissimilar joint part or fillet joint part of copper and steel, or undercut or insufficient throat thickness Repair welding of defective welds (weld defects) such as these is not applied outside the scope of the subject and is neither described nor suggested.

In Patent Document 3, because it is configured to weld the steel section and steel body or barrel of copper clad steel, although MAG welding and CO ₂ welding of steel materials to each other becomes possible construction Since the copper clad steel material is used for the heat transfer fin, there is a problem that the manufacturing cost is high and the weight is increased. Further, since the copper-side thickness of the copper clad steel material is thin, there is a limit to the heat removal performance, so it is not suitable for heat transfer fins that require higher heat removal performance. Also, in Patent Document 3, as in Patent Documents 1 and 2, the use of a SiCu wire, welding of a dissimilar joint between a copper material and a steel material, or welding such as undercut or insufficient throat thickness. Repair welding of defective parts has not been applied outside the scope, and is neither described nor suggested.

  Moreover, in patent document 4, since it is the structure which provides heating means, such as an arc welding torch, a high frequency coil, or a laser, in the back position and / or the front position of this welding means, the enlargement of an apparatus, Problems such as generation of unweldable parts due to interference with the welding object, instability of arc behavior due to the influence of electromagnetic force of the high-frequency coil, and insufficient heating due to the reflection of laser irradiation are expected. In Patent Document 4, the heat transfer fin and the main body are welded using a Ni welding wire by the MIG welding torch of the first welding means, and the weld bead is welded by the MIG welding torch of the second welding means. The heat transfer fin is welded, and the same kind of welding torch and the same kind of welding wire are not used. In addition, use of SiCu wire and repair welding of defective welds such as undercuts and insufficient throat thickness are not applied outside the scope of the subject, and are neither described nor suggested.

  Moreover, in patent document 5, while using a copper plate with a wide plate | board width, it is a structure which needs the process of bending forming etc. in order to provide a parallel part in the both ends of a copper plate width direction, and there exists a problem that manufacturing cost becomes high. is there. In addition, since the overlapped fillet joint is formed by bringing the parallel part into close contact with the outer peripheral surface of the container body and the inner peripheral surface of the outer cylinder, and this overlapped fillet joint is subjected to MIG welding or MIG brazing, a large welding input is obtained. The amount of heat is required, and further, a dent such as an undercut that is likely to occur at the weld bead toe on the copper side may lead to a lack of throat thickness or an insufficient effective cross-sectional area of the weld. Further, in Patent Document 5, repair welding of an undercut or poorly welded portion (weld defect portion) with insufficient throat thickness is not applied outside the object, and is not described or suggested at all.

  On the other hand, in patent document 6, since it is a friction stir welding of the joint member which uses the aluminum alloy different from a copper material and steel materials as a base material, and it is a solid phase joining method different from arc welding (melting joining), It cannot be applied to different types of joints. In addition, the repair area is formed by cutting and removing defective portions such as cracks and pits included in the joining bead by grinder processing or the like, and it is necessary to perform cutting work in advance. Further, the repair bead is formed by TIG welding using a welding rod of the same material as the base material (aluminum alloy), and application of MIG welding is avoided due to aesthetic problems. In addition, in Patent Document 6, for the main welding using a SiCu wire, or for repair welding a poorly welded part (welding defect part) having an undercut or a throat thickness short using the same SiCu wire, It has not been applied outside the scope and has not been described or suggested.

  Moreover, in patent document 7, the defect part (defects peculiar to nuclear reactors, such as a crack and a defect | defect) including a weld part and a clad part is cut off mechanically, and the operation | work which cuts in advance is needed. . In addition, after removing the defective part, depending on the difference in the remaining height of the clad part, repairing the removed part by properly using overlay welding by temper bead method or normal overlay welding I have to. Since overlay welding (repair welding) employs TIG welding and requires multi-pass multi-pass repair welding, there is a problem that much time, labor, and cost are required. Although the material of the welding wire used for repair welding is not described, since the material of the clad is a Ni-based alloy, it is presumed that the welding wire of the same type as this is used. For this reason, it is impossible to repair-weld a defective part of a clad part using copper system wires, such as CuSi wire. Moreover, in patent document 7, like the case of patent document 6, using a CuCu wire, welding the dissimilar-metal joint part and fillet joint part of copper and steel, or undercut, throat thickness lack, etc. The repair welding of the poorly welded part is not applied outside the scope, and is neither described nor suggested.

  Moreover, in patent document 8, a crack part can be repair-welded with the monitoring camera which images a crack part, such as a crack, the welding control means to track the crack part, and the welding head to repair. However, the structural member to be repaired is a device used in a radiation environment such as a nuclear reactor, the repair posture is a horizontal posture, and a flux wire containing a penetration depth promoting metal oxide is welded in the welding direction. Since repair welding is performed by inserting from above the molten pool in a direction perpendicular to the weld pool, it is considered that the present invention is limited to application to crack repair of a planar member surface with a special structural member. In addition, since a flux wire containing a penetration depth promoting metal oxide is used, it cannot be applied to main welding of a dissimilar joint between copper and steel or repair welding of a defective portion thereof. Also, in Patent Document 8, as in Patent Documents 6 and 7, the use of SiCu wire, undercuts different from cracks and cracks, and repairs welds with poor throat thickness (weld defects) are repaired. This is not applicable outside the scope of the report and is neither described nor suggested.

The present invention has been made in view of the above points, and the object of the present invention is excellent in repair weldability of poorly welded portions, and reliably prevents defective welded portions such as excessive undercuts and insufficient throat thickness by original repair work. quenched to provide a weld defect portion repair how metal cask welded structure capable of obtaining a quality good repair weld bead and repair cross section.

In order to achieve the above object, a method for repairing a defective welded portion of a metal cask welded structure according to the present invention includes a steel inner cylinder that houses an assembly of spent fuel having a radioactive substance, and an outer side of the inner cylinder. A poorly welded portion that occurs in the course of the main welding process in which a plurality of copper heat transfer copper fins that are arranged at substantially equal intervals in the circumferential direction between the steel outer cylinders arranged coaxially are welded, Alternatively, a welding defect repairing method for a metal cask welded structure in which a welding defect detected in a quality inspection process after welding is repaired and welded in a repair process, the welding defect occurring in the course of the main welding process, Or, when repairing a defective weld that is determined to be unacceptable in the quality inspection process after welding, the same or the same type of welding torch or the same component as the TIG-MIG welding torch or MIG welding torch used in the main welding process. Welding wires and seals Each of the gases is used, and the TIG-MIG welding torch or the MIG welding torch is run in the same direction as the welding direction when the main welding process is performed, and by combined welding or MIG welding of the preceding TIG and the subsequent MIG In order to build up a repair bead by at least repairing a weld bead so as to build up from above the weld bead portion having the weld failure portion, and collecting the weld failure portion in the repair process. Is formed in the main welding process using repair welding conditions substantially the same as the welding conditions used in the main welding process, or other repair welding conditions in which the MIG voltage and the heat input amount are increased more than the repair welding conditions. The TIG-MIG welding torch or MIG melt is placed on a line at a position shifted from the copper toe end of the weld bead to the surface side of the heat transfer copper fin by a predetermined distance. A torch is disposed, and the TIG-MIG welding torch or the MIG welding torch is caused to travel so as to pass at least on the line of the defective welding portion, and the defective welding portion is obtained by composite welding or MIG welding of the preceding TIG and the succeeding MIG. A repair bead is formed by performing repair welding on at least the poor weld portion so as to build up from above the weld bead portion having a crack .

  According to the present invention, repair weldability of defective welded parts is excellent, and original repair work reliably eliminates welded defective parts such as excessive undercuts and insufficient throat thickness, and provides repair weld beads and repair cross-sections with good quality. Can be obtained.

It is a perspective view which shows the structure of the metal cask with a heat-transfer copper fin concerning Example 1 of this invention. It is a fragmentary perspective view which shows the joint welding structure which expanded the A section in FIG. It is a flowchart which shows the outline | summary of the procedure of the welding method of the heat transfer copper fin for metal casks concerning Example 1 of this invention. It is a flowchart which shows the other procedure outline | summary of the welding method of the heat transfer copper fin for metal casks concerning Example 1 of this invention. It is a fragmentary perspective view which shows the shape of the fillet joint part of the inner cylinder outer surface and the end surface part of a heat-transfer copper fin in the metal cask with a heat-transfer copper fin concerning Example 1 of this invention. It is a fragmentary perspective view which shows the shape of the welding part welded to the fillet joint part by the side of the inner cylinder shown in FIG. It is a flowchart which shows the pass / fail determination in the inspection process of the inner cylinder side in a metal cask with a heat-transfer copper fin concerning Example 1 of this invention, and a repair welding process with the shape of the repair welding part which repaired the poor weld part. It is a fragmentary perspective view which shows the shape of the fillet joint part of the outer cylinder inner surface and end surface part of a heat-transfer copper fin in the metal cask with a heat-transfer copper fin concerning Example 1 of this invention. It is a fragmentary perspective view which shows the shape of the welding part welded to the fillet joint part by the side of the outer cylinder shown in FIG. It is a flowchart which shows the pass / fail determination in the test | inspection process of the outer cylinder side in a metal cask with a heat-transfer copper fin concerning Example 1 of this invention, and the repair welding process with the shape of the repair welding part which repaired the poor weld part. It is a figure which shows schematic structure and torch arrangement | positioning of the TIG-MIG welding torch of the integral structure concerning Example 1 of this invention. It is a figure which shows the state which formed the molten pool by the TIG arc and the MIG arc from the state of FIG. It is a perspective view which shows schematic structure and torch arrangement | positioning of the MIG welding torch concerning Example 2 of this invention. It is a figure which shows one Example of the torch arrangement | positioning which carries out TIG-MIG repair welding so that it may build up from the schematic structure of the TIG-MIG welding torch concerning Example 3 of this invention, and a weld bead part. It is a figure which shows one Example of the torch arrangement | positioning which carries out TIG repair welding so that it may build up from the schematic structure of the TIG-MIG welding torch concerning Example 4 of this invention, and a weld bead part. It is a perspective view which shows one Example of the schematic structure of the MIG welding torch concerning Example 5 of this invention, and the torch arrangement | positioning which carries out MIG repair welding so that it may build up from on a weld bead part. It is a perspective view which shows one Example of the torch arrangement | positioning which repair-welds so that it may build up from the repair test method concerning Example 6 of this invention, and a weld bead part. It is a perspective view which shows one Example of the TIG repair test piece of the welding simulation defect part concerning Example 6 of this invention. It is a perspective view which shows one Example of the TIG-MIG repair test piece of the welding simulation defect part concerning Example 6 of this invention. It is a characteristic view which shows the wire welding cross section when changing the welding (repair) speed | rate and wire feed speed concerning Example 6 of this invention. It is a figure which shows the photograph of the test result of the welding cross section of a typical repair bead and the repair presence or absence part when carrying out TIG repair welding from the top of this welding bead after TIG-MIG composite welding concerning Example 6 of this invention. . The characteristic which shows the relationship between the amount of shift of the torch position and the throat thickness before and after repair when TIG repair welding or TIG-MIG repair welding is performed on the main weld bead after TIG-MIG composite welding according to Example 6 of the present invention. FIG. The relationship between the shift amount of the torch position when the TIG repair welding or the TIG-MIG repair welding is performed on the main weld bead after the TIG-MIG composite welding according to Example 6 of the present invention and the bead stack height before and after the repair are shown. FIG. The figure which shows the photograph of the test result of the welding cross section of a typical repair bead and the repair presence or absence part at the time of TIG-MIG repair welding from on the main welding bead after TIG-MIG composite welding concerning Example 6 of this invention. It is.

Hereinafter, a description will be given to repair how the welding defects of the metal cask welded structure of the present invention based on the illustrated embodiments.

  FIG. 1 shows a structure of a metal cask welded structure according to the present embodiment, and FIG. 2 shows a welded structure in which a portion A in FIG. 1 is enlarged.

  In the figure, an inner cylinder 1 is a container for storing an assembly of a plurality of spent fuels (not shown) having radioactive materials therein, and made of steel such as carbon steel having high strength. It has been. On the outside of the inner cylinder 1, a steel outer cylinder 2 made of the same material as the inner cylinder 1 is arranged coaxially so as to surround the inner cylinder 1 (the strength and rigidity of the entire metal cask is high in strength). It is sufficiently secured by a plurality of lids (not shown) for sealing the inner cylinder 1 and the outer cylinder 2 of steel thick plates and the container formed by these. Between the outer surface of the inner cylinder 1 and the inner surface of the outer cylinder 2, dozens of heat transfer copper fins 3 (in a predetermined number called N) are inclined and arranged at substantially equal intervals in the circumferential direction. .

  These N heat transfer copper fins 3 are made of a copper plate made of copper such as pure copper having a high thermal conductivity. By using the copper heat transfer copper fins 3, collapse occurs from the spent fuel assembly. While the heat removal performance for releasing heat to the outside of the inner cylinder 1 and the outer cylinder 2 can be enhanced, it can also contribute to weight reduction and cost reduction.

  As shown in FIG. 2, an inner welded portion (weld bead and its weld cross section) welded by each fillet joint portion 5 on the inner cylinder 1 side is provided on each end surface portion of the N heat transfer copper fins 3. ) 7 is formed, and outer end welds (weld beads and weld cross sections thereof) 10 welded at the fillet joints 8 on the outer tube 2 side are formed on the other end face portions. Yes. The inner welded portion 7 and the outer welded portion 10 of the heat transfer copper fin 3 are not particularly required in strength, but it is necessary to ensure high reliability due to the nature of the material to be stored and stored.

  The angle θ1 between the inner cylinder 1 and the heat transfer copper fin 3 of each fillet joint portion 5 and 8 of the N heat transfer copper fins 3 to be welded, and the outer cylinder 2 and the heat transfer copper fin 3 is determined by the inner cylinder. 1 and the inner surface of the outer tube 2 or both surfaces of the inner tube 1 and the outer tube 2 are inclined at a wide angle in a range of θ1 = 120 degrees ± 15 degrees (105 ≦ θ1 ≦ 135 degrees). .

  Each space 4 adjacent to the N heat transfer copper fins 3 is a place where a resin (not shown) such as a resin material is filled and arranged. These resins are substances that shield radiation emitted from the assembly of spent fuel in a normal line, and after welding, the resin is placed in each space along the inclined surface of the N heat transfer copper fins 3. 4 is filled in each. By arranging the heat transfer copper fins 3 to be inclined at a wide angle, workability during welding is facilitated, and radiation is shielded by the inclined arrangement of the resin filled along the inclined surfaces of the heat transfer copper fins 3. Performance can be increased.

  A method of welding both end surface portions of the heat transfer copper fin 3 in this embodiment to both surfaces of the inner cylinder 1 and the outer cylinder 2 will be described below.

  FIG. 3 is a flowchart showing an embodiment of a welding procedure outline of a metal cask welded structure according to the present embodiment, and FIG. 4 is a flowchart showing an embodiment of a welding procedure outline of another metal cask welded structure. It is.

  The main differences between the flowcharts shown in FIGS. 3 and 4 are that the first welding process 103 on the inner cylinder 1 side including the temporary assembly process for each fillet joint and the outer cylinder including the temporary assembly process for each fillet joint. The construction contents of the welding process 110 on the 2 side are expressed in the number of units on the inner cylinder 1 side by the repeated welding process 105 on the N side welding on the inner cylinder 1 side and the welding process 112 on the outer cylinder 2 side by the repeated welding process 112. And the repeated welding process 106 of welding and inspection and the repeated welding process 113 of welding and inspection in a small number of units on the outer cylinder 2 side.

  For example, as shown in FIG. 3, in the welding procedure (No. 1) 99 of the heat transfer copper fin 3, a wire welding sectional area determining step 102 for determining the wire welding sectional area Aw before welding, and a predetermined number (N). After one end face part of each heat transfer copper fin 3 is abutted to the inner cylinder 1 side to form fillet joint part 5 at N places, or at N places and temporarily attached (for example, by tack welding) The first welding process 103 and the inner cylinder on the inner cylinder 1 side including the temporary assembly process of each fillet joint that is repeatedly welded to the N fillet joint parts 5-1, 5-2,... After the repeat welding step 105 of welding N places on the 1 side and the subsequent inspection step 107 for welding quality on the inner tube 1 side, the other end surface portion of the N heat transfer copper fins 3 is attached to the outer tube 2. The fillet joints 8 are formed at N locations by butting each other, or N locations are formed and temporarily welded and temporarily assembled. The second welding step 110 on the outer tube 2 side including the temporary assembly step of each fillet joint repeatedly welded to the fillet joint portions 8-1, 8-2,. A repeated welding step 112.

  Then, N fillet joints 8 are formed and temporarily welded and temporarily assembled, and then repeatedly welded to the N fillet joints 8-1, 8-2,. By performing (continuous welding), the temporary assembly work and welding work of each fillet joint can be performed efficiently.

  On the other hand, as shown in FIG. 4, in the welding procedure (No. 2) 100 of the heat transfer copper fin 3, each fillet joint to be performed after the wire welding sectional area determining step 102 for determining the wire welding sectional area Aw before welding. In the first welding step 103 on the inner tube 1 side including the temporary assembly step, welding is repeatedly performed one pass at a time at the N fillet joint portions 5-1, 5-2,. (Continuous welding) Both welding and inspection are carried out so that welding is repeated at the N-point welding repeated welding step 105 and the fillet joint portion divided into about 1 to 5 locations, and the welded portion after the welding is inspected. It is divided into a welding process 106 of repeated welding and inspection in a small number of units that repeat the work.

  For example, in the repeated welding process 106 of welding and inspection in a small number of units, which is divided into a small number of units and repeats welding and inspection, a predetermined number (N) of heat transfer copper fins 3 are attached to the outer surface of the inner cylinder 1 to form a corner. After forming N joints or forming N joints and performing temporary assembly by temporary welding, the fillet joints 5-1, 5-2,... Dividing into about 1 part and welding to the fillet joint part 5-1 to 5-5 of the divided parts one by one and welding and inspection of the fillet joint part so as to inspect the welded part And so on.

  On the other hand, in the second welding step 110 on the outer tube 2 side including the temporary assembly step of each fillet joint, N fillet joint portions 8-1 on the outer tube 2 side are provided, as in the case of the inner tube 1 side. 8-2... 8-N repeated welding process (continuous welding) one pass at a time for N places on the outer cylinder 2 side, and a fillet joint portion divided into about 1 to 5 places. In addition to welding one pass at a time, in order to inspect the welded portion, the welding and inspection are repeated in a small number of units in which both welding and inspection operations are repeated, and the welding process 113 is repeated.

  For example, the repeated welding process 113 of the minority unit that repeats welding and inspection on the outer cylinder 2 side is similar to the case of the inner cylinder 2 side, and N fillets formed on the outer cylinder 2 side are the same. The joint portions 8-1, 8-2... 8 -N are divided into about 1 to 5 locations in advance, and welded to the divided 1 to 5 fillet joint portions 8-1 to 8-5 one pass at a time. At the same time, the welding and inspection of the fillet joint are repeated so as to inspect the weld.

  In this way, by selecting one of two types of operations (continuous welding or repetition of welding and inspection), it is possible to improve work efficiency with priority on welding or improvement in welding quality with priority on inspection.

  On the other hand, the inspection processes 107 and 114 on the inner cylinder 1 side and the outer cylinder 2 side are processes for inspecting the quality of each welded part that has been welded as described above. The inspection processes 107 and 114 on the inner cylinder 1 side and the outer cylinder 2 side are performed by the first welding process 103 on the inner cylinder 1 side including the temporary assembly process of each fillet joint and the welding of N places on the inner cylinder 1 side. After the end of the repeated welding process 105, or the first welding process 103 on the inner cylinder 1 side including the temporary assembly process of each fillet joint, the repeated welding process 105 for welding N points on the inner cylinder 1 side, and each fillet joint The second welding process 110 on the outer cylinder 2 side including the temporary assembly process, and the necessary welding position after the repeated welding process 112 of N places on the outer cylinder 2 side are provided. Further, in the inspection steps 107 and 114 on the inner cylinder 1 side and the outer cylinder 2 side, the quality of each welded portion is inspected, and the repaired welding step of repairing the welded portion that has failed the inspection and its vicinity. 109 and 116 are provided.

  Further, in the inspection process 117 on the inner cylinder 1 side and the inspection process 120 on the outer cylinder 2 side when both the welding and inspection operations are repeatedly performed, whether or not the weld bead is well formed in the corresponding welded portion, Inspection / confirmation of welding quality, such as whether or not there are defects such as cracks and undercuts, and whether or not the throat thickness L1, bead height H1, penetration depth c, etc. are satisfied.

  When the inspection process 117 on the inner cylinder 1 side and the inspection process 120 on the outer cylinder 2 side for inspecting the welding quality fail, repair welding processes 119 and 122 are performed on the rejected welded part and its vicinity. I am trying to repair it.

  In these repair welding processes 109, 116, 119, and 122, for example, the MIG voltage and the heat input amount are increased more than the repair welding conditions or repair welding conditions that are substantially the same as the welding conditions when the fillet joint is main welded. By using other repair welding conditions and performing one-pass overlay and repair welding, the overlay repair can be performed so that the defective portion (welding failure portion) can be easily eliminated.

  In addition, the repair method of a poor weld part is later mentioned using another Example (FIG. 7, FIG. 10, FIG. 14-16).

  First, in the wire welding cross-sectional area determination step 102 performed before welding, the throat thickness L1 of the inner welded portion 7 to be formed on the predetermined fillet joint portion 5 is equal to or greater than the plate thickness T1 of the heat transfer copper fin 3 (L1 ≧ T1). The wire welding cross-sectional area Aw is calculated and determined from the wire feed speed Wf or the wire feed speed Wf, the wire diameter d, and the predetermined welding speed V.

  The throat thickness L1 of the inner welded portion 7 (or outer welded portion 10) is the molten bottom portion on the heat transfer copper fin 3 side, as shown in the wire welding cross-sectional area Aw determination step 102 in FIGS. This is the minimum distance from the weld bead surface. Moreover, the inner side welding part 7 of the fillet joint part 5 shown in the location of the determination process 102 of the wire welding cross-sectional area Aw is formed by welding one end surface part of the heat transfer copper fin 3 to the outer surface of the inner cylinder 1. However, it is also assumed that the other end surface portion of the heat transfer copper fin 3 is welded to the inner surface of the outer cylinder 2 to form the other outer welded portion 10, which is shown in FIG. 2. It is omitted because it is similar to the welded structure.

  Next, in the first welding process 103 on the inner cylinder 1 side including the temporary assembly process of each fillet joint shown in FIGS. 3 and 4, a predetermined number (N) of heat transfer copper fins 3 are attached before the main welding. The inner cylinder 1 is temporarily welded to be temporarily assembled. For example, as shown in FIG. 5, each end face part of one side of a predetermined number (N) of heat transfer copper fins 3 is abutted against the outer surface of the steel inner cylinder 1, and each fillet joint part 5- 1, 5-2,..., 5-N are formed at substantially equal intervals, or are formed at the same time, and are temporarily assembled (for example, by temporary welding).

  As shown on the right side in FIG. 5, when forming and temporarily assembling fillet joint portions 5-1, 5-2... 5-N, for example, temporary welding is performed by a welding method such as TIG welding. It is preferable to temporarily assemble the fillet joint portion by forming the temporary attachment portions (k1, k2,... Kp) having a predetermined length X1 at predetermined intervals X2. The tacking length X1 to be tack welded is in the range of 15 mm to 50 mm (15 ≦ X1 ≦ 50 mm), and the distance interval X2 between the tacks is in the range of 200 mm to 600 mm (200 ≦ X2 ≦ 600 mm). It is good to make it.

  The number of temporary attachments n varies depending on the weld line length Xw to be welded. For example, the start side or the end side is a number obtained by dividing the weld line length Xw substantially equally by the distance interval X2 between the temporary attachments. If the total number including one of the above is added, (welding line length Xw / distance interval X2) +1, and the provisional number n can be easily determined. Further, each temporary attachment position may be determined as the start position of the weld line, the respective positions for each distance interval X2 and the end position of the weld line from the start position. Further, the weld lines (6-1, 6-2,..., 6-N) of the joint base material to be tack welded are the same as those in the case of the main welding, and from the end face corners of the heat transfer copper fins 3. The distance S3 (second distance) for shifting the welding torch to the heat transfer copper fin surface side is preferably in the range of 1 mm to 3 mm (1 ≦ S3 ≦ 3 mm).

  If the tacking length X1 is too short than 15 mm, the strength tends to be insufficient due to insufficient tacking length. Conversely, if the tacking length X1 is too long, the tacking part is remelted during the main welding process. It is easy to cause trouble in forming the weld bead. Further, if the distance X2 between the tacks is too short than 200 mm, the number of tacks increases and the time for the tacking work increases. On the other hand, if it is too long, the strength is insufficient due to the shortage of the tacks. This is not preferable because it is easy to be warped and deformed during the actual welding. Also, if the shift distance S3 for shifting the welding torch is shorter than 1 mm, the arc and the molten pool during the tack welding are likely to be shifted to the steel side (inner cylinder 1 side). It tends to become insufficient in strength due to insufficient melting or undercut on the 3rd side. On the other hand, if the shift distance S3 is longer than 3 mm, the arc and the melt pool during tack welding are likely to be shifted to the heat transfer copper fin 3 side. Since it becomes easy to become, it is not preferable.

  By performing TIG temporary welding at predetermined intervals (X1) at predetermined intervals (X1) at the temporary attachment positions determined in this manner, temporary attachment portions with predetermined lengths even in the case of the inner cylinder 1 side. N pieces (k1, k2,..., Kn) can be easily formed, and a fillet joint portion with small bending and warping deformation of the weld line to be welded can be easily formed temporarily. Moreover, the welding assembly and manufacture of a metal cask welding structure can also be continued by temporary attachment by this temporary attachment method.

  Moreover, in TIG tack welding for forming n tacking portions at predetermined positions of the fillet joint portions 5-1, 5-2,..., 5-N, the main welding after the tack welding is performed. It is preferable to use a mixed gas of SiCu wire and Ar gas and He gas having the same components as the welding wire and shield gas to be used.

  Moreover, the welding torch is disposed so as to pass over the weld line 6-1 of the fillet joint portion 5-1 to be tack welded, and the fillet joint portion 5-1 to be provisionally attached from the tip opening of the welding torch and The mixed gas is flowed out to the vicinity surface portion to generate a TIG arc at the temporary attachment start position, and a non-powered SiCu wire is fed into the TIG arc and the molten pool at a low speed, and the direction of the preceding wire and the subsequent TIG arc The welding torch is moved and moved, and a TIG tack welding of a predetermined length is applied to the fillet joint portion to form a temporary bead, thereby providing a temporary bead (k1, k2,. .. kn) can be obtained satisfactorily.

  Also, by TIG tack welding using SiCu wire, even when dissimilar material welding of copper and steel, copper, steel and Si are mixed properly in a state where they can be dissolved, and good without cracks A temporary bead and a temporary welded cross section can be obtained. Furthermore, it becomes possible to perform the main welding of the fillet joint portion having a plurality of temporary attachment portions.

  In FIG. 5, only two heat transfer copper fins 3 are shown and other portions are omitted, but a predetermined number of heat transfer copper fins 3 to be welded are circles on the outer surface of the inner cylinder 1. Inclined and arranged at substantially equal intervals in the circumferential direction.

  FIG. 6 is a partial perspective view showing the shape of a welded portion that is finally welded to the fillet joint portion on the inner cylinder side shown in FIG. 5.

  In the main welding on the inner cylinder 1 side of the present embodiment, the outer cylinder 2 is not arranged, but the heat transfer copper fins 3 are inclinedly arranged on the outer surface of the inner cylinder 1 to form wide-angle fillet joint portions 5-1, 5. -2 ... After 5-N is formed and temporarily attached and temporarily assembled, by TIG-MIG welding torch TIG-preceding TIG and subsequent MIG combined welding or MIG welding of main welding by MIG welding torch .., 7-N are formed by welding one pass at a time in order.

  In this way, it is sufficient to perform the main welding in order one pass at a time on the weld line of each fillet joint portion 5-1, 5-2... 5-N after temporary assembly (temporary welding). Throat thickness L1 and bead height H1 and heat conduction cross-sectional area effective for heat removal can be reliably ensured, and a shallow penetration weld bead and weld cross sections 7-1, 7-2,... 7 -N can be obtained.

  In addition, as described above, the first welding process 103 (main welding process) on the inner cylinder 1 side including the temporary assembly process of each fillet joint includes the fillet joints on the inner cylinder 1 side to be temporarily assembled and welded. Is a step of performing temporary welding after temporary welding and temporarily assembling.

  As shown in FIGS. 3 to 6, in the first welding process 103 on the inner cylinder 1 side including the temporary assembly process of each fillet joint, a predetermined number (N) of heat transfer copper fins 3 are connected to the inner cylinder 1. The fillet joint portion 5 is formed at N locations, or N locations are formed, and are temporarily attached by temporary welding, and then the main weld is applied to the provisionally-attached joint portion. In the main welding on the inner cylinder 1 side after temporary assembly, for example, a predetermined number (N) of heat transfer copper fins 3 are attached to the outer surface of the inner cylinder 1 to form fillet joints 5 at N locations, or N locations On the inner cylinder 1 side, which is repeatedly welded (continuously welded) to the N fillet joint portions 5-1, 5-2,... The N welding welding process 105 and the N fillet joints 5-1, 5-2... 5-N are divided into about 1 to 5 places in advance, and the divided 1 to 5 places are divided. The fillet joints 5-1, 5-2, 5-3, 5-4, 5-5 are welded, and both the welding and inspection operations are repeated so as to inspect the welds. It is divided into welding in a small number of units and repeated welding process 106 of inspection.

  In the repeated welding step 105 of N welding (main welding) on the inner cylinder 1 side, welding of N fillet joint portions 5-1, 5-2,..., 5-N to be welded for each pass is started. For each welding line from the position to the end position (welding lines 6-1, 6-2,..., 6-N indicated by dotted lines on the lower surface of the heat transfer copper fin 3), a CuSi wire containing silicon is used, Welding is performed in order, one pass at a time, by composite welding of the preceding TIG and the subsequent MIG of the main welding by the TIG-MIG welding torch, or MIG welding of the main welding by the MIG welding torch.

  For this reason, in the repeated welding process 105 of welding of N places on the inner cylinder 1 side, for example, the joint (both inner cylinder 1 and heat transfer copper fin 3) side to be welded is rotated and moved by a rotary drive device or the like. As in the case of tack welding, after changing the posture of the weld line 6-1 of the fillet joint portion 5-1 to be welded in the vertical direction, a TIG-MIG welding torch having an integral structure on the weld line 6-1 Alternatively, the MIG welding torch is positioned in a downward posture. The welding line when both end portions of the heat transfer copper fin 3 are flat surfaces is a position obtained by shifting the wire position or torch position (including electrode position) by a predetermined distance from the end face corner portion to the surface side of the heat transfer copper fin 3. The shift amount S1 (first distance S1) is preferably set in the range of 0 mm to 4 mm (0 ≦ S1 ≦ 4 mm).

  In addition, the TIG-MIG welding torch or the MIG welding torch having a monolithic structure in the downward posture is welded along the weld line 6-1 from the welding start position to the end position to perform one pass welding, and a weld bead and a weld cross section. The parts 7-1 and 7-2 may be formed.

  In this way, by performing the main welding by shifting the wire position or the torch position to the heat transfer copper fin 3 side, heat melting of the heat transfer copper fin 3 is promoted, and the penetration depth c on the steel side is suppressed. Therefore, the throat thickness L1 having a sufficient size and the heat conduction cross-sectional area effective for heat removal can be reliably ensured, and a shallow penetration weld bead and weld cross sections 7-1 and 7-2 can be obtained. it can.

  When the one-pass welding of the welding line 6-1 is completed, the welding torch is moved around, and in the welding of the next welding line 6-2, the joint side is rotated again, and the corresponding welding line 6-2 is moved vertically. After changing the posture in the direction, the welding torch that has been moved to avoid is moved along the welding line 6-2 to perform positioning in a downward posture. One-pass welding may be performed while the welding torch travels along the welding line 6-2.

  In this way, the operation of changing the orientation of the weld line of the corresponding fillet joint portion 5, the operation of positioning the welding torch on the weld line, the operation of performing one-pass welding on the weld line while running the welding torch, 1 pass By performing a series of repetitive operations such as an operation for avoiding the welding torch after welding construction, each welding line 6-1, 6-2. As shown in FIG. 6, a weld bead and weld cross sections 7-1, 7-2... 7-N can be formed, respectively.

  Note that composite welding or MIG welding of the preceding TIG and the subsequent MIG will be described later using another embodiment (FIGS. 11 to 14).

  On the other hand, the welding operation is the same in the welding process 106 of the welding and inspection in the small number unit on the inner cylinder 1 side that repeats the inspection of the inner cylinder 1 side (1-5 locations) and the inspection of the welded portion. As described above, a single-pass welding is performed while the TIG-MIG welding torch having a monolithic structure in the downward posture or the MIG welding torch is run along the welding line 6-1 from the welding start position to the end position. And it is good to form the welding cross-section part 7-1. After welding, inspection of the welding quality is performed in the inspection process 117 on the inner cylinder 1 side, and when the inspection of the welding quality is unsuccessful, the repaired welding process 119 repairs the rejected welded part and its vicinity. I am trying to repair it.

  By using CuSi wire to perform composite welding of preceding TIG and subsequent MIG or MIG welding, copper, steel, and Si can be mixed together in a state where they can be dissolved even in the case of dissimilar material welding of copper and steel. As a result, it is possible to form a good weld bead and weld cross section (welded part) without cracks.

  For example, Si and Mn are substances belonging to eutectic type II that are soluble in Cu and Fe. For this reason, by performing welding using the CuSi wire containing Si and Mn, It is presumed that a good weld with no cracks can be obtained by mixing the steel and the steel and Si in a solid solutionable state.

  On the other hand, it is also possible to use a pure copper Cu wire with high thermal conductivity, but in the case of a pure copper Cu wire, compared to CuSi wire containing silicon, different materials welding of copper and steel Since the weldability and weld quality are inferior and the cracking susceptibility is high, it was not adopted in the welding method of this example.

  In this embodiment, the weld bead of each fillet joint portion 5-1, 5-2,..., 5-N and the weld cross-section portions 7-1, 7-2,. At least the throat thickness L1 of the welded portion is formed to be not less than the plate thickness T1 of the heat transfer copper fin 3 (L1 ≧ T1), and the penetration depth c on the inner cylinder 1 side is not less than 0.05 mm and not more than 6 mm ( 0.05 ≦ c ≦ 6 mm). Preferably, the penetration depth c may be 0.05 mm or more and 4 mm or less (0.05 ≦ c ≦ 4 mm).

As a result, it is possible to reliably secure a throat thickness L having a sufficient size and a heat conduction cross-sectional area effective for heat removal at the welded portion of each heat transfer copper fin 3 on the inner cylinder 1 side, and defects such as cracks. It is possible to obtain a weld bead and a welded cross-section with good quality. Moreover, it can contribute to improvement of heat removal performance and reduction of manufacturing cost. Furthermore, also about the tensile strength of a weld part, the intensity | strength of 100 N / mm < ² > or more can be obtained reliably.

  If the above-mentioned throat thickness L1 is too smaller than the plate thickness T1 of the heat transfer copper fin 3, for example, it is necessary to conduct heat from the inner cylinder 1 side to the heat transfer copper fin 3 side via the inner welded portion 7. As a result, the heat conduction cross-sectional area is reduced, which hinders improvement of heat removal performance. Therefore, the throat thickness L1 of the welded portion is formed to be not less than the plate thickness T1 of the heat transfer copper fin 3 (L1 ≧ T1), and the bead height H1 is not less than T1 (H1 ≧ T1).

  Moreover, the undercut depth R which may occur at the bead toe portion on the heat transfer copper fin 3 side is suppressed to (0.1 × T1) or less. Furthermore, if the penetration depth c on the inner cylinder 1 side is too deep, the steel melting ratio (dilution rate) with respect to the cross-sectional area of the welded portion increases, so the thermal conductivity of the welded portion decreases and crack susceptibility increases. It tends to be expensive. If the penetration depth c is too shallow, the tensile strength tends to decrease due to insufficient bonding with the steel side.

  Therefore, as described above, the penetration depth c on the inner cylinder 1 side is formed to be 0.05 mm or more and 6 mm or less (0.05 ≦ c ≦ 6 mm). The penetration depth c is preferably 0.05 mm to 4 mm (0.05 ≦ c ≦ 4 mm).

  On the other hand, excessive undercuts that may occur in the process of welding each heat transfer copper fin 3 in the first welding process 103 (main welding process) on the inner cylinder 1 side including the temporary assembly process of each fillet joint, , Welded defective parts such as throat thickness deficiency or bead height deficient, or undercut excessive parts that may be detected in quality inspection processes 107 and 117 after welding, such as throat thickness deficient or bead height deficient It is necessary to carry out repair welding (overlay repair).

  FIG. 7 is a partial perspective view showing the pass / fail determination in the inspection process on the inner cylinder side in the metal cask welded structure according to the first embodiment of the present invention, and the shape of the repair weld part in which the defective weld part is repaired in the repair welding process. It is.

  In the inspection steps 107 and 117 on the inner cylinder side of this embodiment, in order to determine whether or not the welding quality is acceptable, for example, the throat thickness L1 is L1 <T1, or the bead height H1 is H1 <T1, or the undercut depth R When R> (0.1 × T1), it is judged as rejected (welding failure), and when L1 ≧ T1, or H1 ≧ T1, or R ≦ (0.1 × T1), it passes (welded). (Good). Repair welding is performed in the repair welding process 109 and 119 on the defective weld portion and its vicinity in the failure determination.

  For example, when repairing a defective weld portion determined to be rejected, the TIG-MIG welding torch used in the first welding process 103 (main welding process) on the inner cylinder 1 side including the temporary assembly process of each fillet joint. Or, using the same or the same type of welding torch as the MIG welding torch, welding wire and shield gas of the same component, respectively, it was constructed in the first welding process 103 on the inner cylinder 1 side including the temporary assembly process of each fillet joint Welding bead portions 7-1 and 7-2 having poorly welded portions by running a TIG-MIG welding torch or a MIG welding torch in the same direction as the current welding direction and performing composite welding or MIG welding of the preceding TIG and the subsequent MIG. In order to build up from above, repair welding is applied to the welded defective part and its vicinity to eliminate the welded defective part, and a good repair weld bead (repair bead) 70-1 is formed. The

  In addition, when repairing defective welds in the repair welding processes 109 and 119, the repair is substantially the same as the welding conditions used in the first welding process 103 on the inner cylinder 1 side including the temporary assembly process of each fillet joint. It is formed in the first welding process 103 on the inner cylinder 1 side including the temporary assembly process of each fillet joint using welding conditions or other repair welding conditions in which the MIG voltage and the heat input amount are increased from the repair welding conditions. TIG-MIG welding torch or MIG welding torch on a line at a position shifted by a predetermined distance from the bead toe portion on the copper side of weld bead portions 7-1 and 7-2 to the surface side of heat transfer copper fin 3 It is good to arrange.

  And a TIG-MIG welding torch or a MIG welding torch is run so as to pass on the line of the poorly welded part and the vicinity thereof, and a weld bead having a poorly welded part by combined welding of the preceding TIG and the succeeding MIG or MIG welding Repair welding is performed on the poorly welded part and the vicinity thereof so as to build up from above the parts 7-1 and 7-2 so that the poorly welded part disappears and a good repair weld bead 70-1 is formed. I am doing so.

  By carrying out repair welding in this way, weld defects such as insufficient throat thickness or insufficient bead height and excessive undercut depth can be reliably eliminated, and weld beads (repair cross section) 70-1 with good quality can be reliably eliminated. 70-2 can be obtained. In addition, the repair of the metal cask welded structure can be continued by the repair by this repair method.

  In the quality inspections 1071 and 1171 of the repaired welds that are performed after the repairs are completed, it is determined to pass if the repaired throat thickness L2 ≧ T1, bead stack height H2 ≧ T1, and undercut depth R ≦ (0.1 × T1). Thus, the process proceeds to the second welding step 110 on the outer cylinder 2 side including the temporary assembly step of each fillet joint in the next step.

  In this way, even when poor welding occurs, the original repair welding can reliably eliminate defective welds such as insufficient throat thickness, insufficient bead height, and excessive undercut depth, resulting in good quality. It is possible to obtain a large repair weld bead (repair cross section) 70-1 and 70-2, and to secure a large weld throat thickness and a heat conduction cross section that contributes to an improvement in heat removal performance.

  Next, in the second welding step 110 (main welding step) on the outer cylinder 2 side including the temporary assembly process of each fillet joint, the temporary assembly and each fillet joint on the outer cylinder 2 side to be welded are tack-welded. This is the step of performing the main welding after the temporary assembly.

  As shown in FIGS. 3 and 4, in the second welding process 110 on the outer cylinder 2 side including the temporary assembly process of each fillet joint, the first on the inner cylinder 1 side including the temporary assembly process of each fillet joint. Welding process 103, N-weld welding repeated welding process 105 on the inner cylinder 1 side, welding and inspection repeating welding process 106 on the inner cylinder 1 side in the minor unit, or after the inner cylinder 1-side inspection process 107, After the end of 117, each fillet joint on the outer cylinder 2 side is temporarily assembled (temporary welding), and then the main welding is applied to the provisional joint portion.

  For example, in the temporary assembly on the outer cylinder 2 side, as shown in FIG. 8, a predetermined number of the cylindrical outer cylinders 2 are arranged on the outer peripheral side of the heat transfer copper fins 3 that are welded on the inner cylinder 1 side. The other end face portions of the heat transfer copper fin 3 of (N) are abutted to form wide-angle fillet joint portions 8-1, 8-2 to 8 -N, respectively, at approximately equal intervals, or Each of these is formed and temporarily assembled by temporary welding.

  As shown on the right side in FIG. 8, when forming and temporarily assembling fillet joint portions 8-1, 8-2... 8 -N, for example, temporary welding is performed by a welding method such as TIG welding. The fillet joint portions may be provisionally assembled by forming temporary attachment portions (k1, k2,... Kp) having a predetermined length X1 at predetermined intervals X2.

  As in the case of the inner cylinder 1 side described above, even in the case of the outer cylinder 2 side, the temporary attachment length X1 to be temporarily attached is in the range of 15 mm to 50 mm (15 ≦ X1 ≦ 50 mm). The distance interval X2 is preferably in the range of 200 mm to 600 mm (200 ≦ X2 ≦ 600 mm). The number of temporary attachments n varies depending on the weld line length Xw to be welded. For example, the start side or the end side is a number obtained by dividing the weld line length Xw substantially equally by the distance interval X2 between the temporary attachments. If the total number including one of the above is added, (welding line length Xw / distance interval X2) +1, and the provisional number n can be easily determined. In addition, each temporary attachment position may be determined as a weld line start position, a position for each distance interval X2 from the start position, and a weld line end position.

  In the case of the outer cylinder 2 side as in the case of the inner cylinder 1 side, TIG tack welding is performed at a predetermined length (X1) at predetermined intervals (X2) at the temporary attachment position thus determined. However, it is possible to easily form n temporary attachment portions each having a predetermined length, and it is possible to easily manufacture a fillet joint portion in which bending or warping deformation of a weld line to be welded is small. . In addition, as described above, the welding assembly and manufacturing of the metal cask welded structure can be continued by the temporary attachment according to the temporary attachment method.

  In addition, in TIG tack welding for forming n tacking portions at predetermined positions of the fillet joint portions 5-1, 5-2,..., 5-N, the main welding after the tack welding is performed. It is preferable to use a mixed gas of SiCu wire and Ar gas and He gas having the same components as the welding wire and shield gas to be used.

  Similarly to the case of tack welding on the inner cylinder 1 side, even in the case of the outer cylinder 2, the welding torch is passed so as to pass over the weld line 9-1 of the fillet joint portion 8-1 to be tack welded. Arranged and let the mixed gas flow out from the front end opening of the welding torch toward the fillet joint portion 8-1 and its vicinity surface portion to generate a TIG arc at the temporary attachment start position, and feed no SiCu wire Is fed at a low speed into the TIG arc and into the molten pool, the welding torch is moved in the direction of the TIG arc following the preceding wire, and a temporary bead is formed on the fillet joint to form a temporary bead. By performing TIG tack welding and forming a tack bead, a tack bead (k1, k2,..., Kn) having a predetermined tack length X1 can be obtained satisfactorily.

  Also, by TIG tack welding using SiCu wire, even when dissimilar material welding of copper and steel, copper, steel and Si are mixed properly in a state where they can be dissolved, and good without cracks A temporary bead and a temporary welded cross section can be obtained. Furthermore, it becomes possible to perform the main welding of the fillet joint portion having a plurality of temporary attachment portions.

  In FIG. 8, only two heat transfer copper fins 3 are shown and the other parts are omitted as in FIG. 5, but a predetermined number (N) of heat transfer copper fins 3 to be welded are shown. Are arranged at substantially equal intervals on both surfaces of the inner cylinder 1 and the outer cylinder 2, and the weld beads and weld cross sections 7-1, 7-2,... It has been formed, and the joint side posture is reversed and illustrated.

  FIG. 9 is a partial perspective view showing the shape of a welded portion that is finally welded to the fillet joint portion on the outer cylinder side shown in FIG. 8.

  In the main welding on the outer cylinder 2 side of the present embodiment, the heat transfer copper fins 3 are inclinedly arranged on the inner surface of the outer cylinder 2 so that the wide-angle fillet joint portions 8-1, 8-2,. After forming and provisionally attaching and temporarily assembling, as in the case of the inner cylinder 1 side, MIG welding of the main welding with the TIG-MIG welding torch and the main welding of the preceding TIG and the subsequent MIG or the main welding with the MIG welding torch In this way, welding is carried out one by one in order to form weld beads (welded cross sections) 10-1, 10-2... 10-N.

  In this way, it is sufficient to perform the main welding one by one in order from the weld line of each fillet joint portion 8-1, 8-8... 8 -N after temporary assembly (temporary welding). Throat thickness L1 and bead height H1 and heat conduction cross-sectional area effective for heat removal can be ensured reliably, and shallow penetration weld beads (welding cross sections) 10-1, 10-2,... 10-N can be obtained.

  Further, in the second welding step 110 on the outer tube 2 side including the temporary assembly step of each fillet joint, as shown in FIGS. 3, 4, 8 and 9, the fillet joint portion is formed on the outer tube 2 side. Are formed at N locations, or are formed at N locations and temporarily assembled by temporary welding, and then repeatedly welded one pass at a time at each of the N fillet joint portions 8-1, 8-2,. Welding) Repeat welding process 112 of N places (main welding) on the outer cylinder 2 side to be welded, and 1 pass to 1 to 5 fillet joint parts 8-1, 8-2, ... 8-N. In addition to welding, the welding process after the welding is inspected, and the welding and inspection are repeated in a small number of units on the outer cylinder 2 side that repeats both welding and inspection operations.

  For example, in the repeated welding process 112 for welding N places on the outer cylinder 2 side, as in the repeated welding process 105 for welding N places on the inner cylinder 1 side, N fillet joints to be welded for each pass are provided. Each weld line from the welding start position to the end position of each of the parts 8-1, 8-2,..., 8-N (welding lines 9-1, 9- shown by the dotted lines described on the lower surface of the heat transfer copper fin 3) 2... 9-N are welded in order, one pass at a time, by using a CuSi wire containing silicon and performing composite welding of the preceding TIG and the succeeding MIG or MIG welding.

  For this reason, as in the case of the inner cylinder 1 side, even in the case of the main welding on the outer cylinder 2 side, the joint to be welded (the inner cylinder 1, the outer cylinder 2 and the heat transfer copper fin 3) side is connected with a rotary drive device or the like After rotating and moving the weld line 9-1 of the fillet joint part 8-1 to be fully welded in the vertical direction in the same manner as in the case of tack welding, an integrated structure is formed on the weld line 9-1. The TIG-MIG welding torch or MIG welding torch is positioned in a downward posture.

  As described above, the welding line in the case where both end portions of the heat transfer copper fin 3 are flat surfaces has a predetermined distance between the wire position or the torch position (including the electrode position) from the end face corner portion to the surface side of the heat transfer copper fin 3. The shift amount S1 is preferably set in a range of 0 ≦ S1 ≦ 4 mm. In addition, the TIG-MIG welding torch or the MIG welding torch having a one-piece structure in the downward posture is welded along a weld line 9-1 from the welding start position to the end position, and then welded (welded cross section). Part) 10-1 may be formed.

  Thus, by shifting the wire position or torch position to the heat transfer copper fin 3 side and welding, the heat melting of the heat transfer copper fin 3 is promoted and the penetration depth on the steel side is suppressed. The throat thickness L1, the bead height H1, and the heat conduction cross-sectional area effective for heat removal can be reliably ensured, and a shallow penetration weld bead and weld cross section can be obtained.

  When the one-pass welding of the welding line 9-1 is completed, the welding torch is moved around to avoid the welding of the next welding line 9-2 and the welding of the subsequent welding line, as described above. Operation to change the position of the weld line of the fillet joint, operation to position the welding torch on the weld line, operation to perform 1-pass welding on the weld line while running the welding torch, avoid welding torch after 1-pass welding operation By performing a series of repetitive operations such as operations, a weld bead (welded cross section) is provided on each of the welding lines 9-1, 9-2,... 9-N of a predetermined number (N) of fillet joints. 10-1, 10-2... 10-N can be formed.

  On the other hand, in the case of the inner cylinder 1 side even in the repeated welding step 113 of welding and inspection on the outer cylinder 2 side which repeats the welding (1 to 5 places) on the outer cylinder 2 side and the inspection of the welded portion, Similarly, as described above, the one-pass welding is performed while the TIG-MIG welding torch or the MIG welding torch having the downward structure is moved along the welding line 9-1 from the welding start position to the end position. Then, it is preferable to form a weld bead (welded cross section) 10-1. The welding quality inspection process 120 on the outer cylinder 2 side is performed after welding, and if the welding quality inspection process 120 on the outer cylinder 2 side fails, the rejected welded part and its vicinity are repaired. Repair is performed in the welding step 122.

  Moreover, as shown in FIG.4, FIG8 and FIG.9, the weld bead (welding cross-section part) 10-1 of each fillet joint part 8-1, 8-2, ... 8-N welded, 10-2... 10-N, at least the throat thickness L1 of the weld is formed to be equal to or greater than the plate thickness T1 of the heat transfer copper fin 3 (L1 ≧ T1), and the bead height H1 is equal to or greater than T1 (H1 ≧ T1). In addition, the undercut depth R is suppressed to (0.1 × T1) or less.

  As a result, as in the case of the inner cylinder 1 side described above, the welded portion of each heat transfer copper fin 3 on the outer cylinder 2 side has a sufficiently large throat thickness L and a heat conduction cross-sectional area effective for heat removal. Can be reliably ensured, and weld beads (welded cross-sections) 10-1, 10-2,..., 10-N with good quality without defects such as cracks can be obtained.

  In the inspection step 114 on the outer cylinder 2 side after the repeated welding on the outer cylinder 2 side is completed, the weld beads are well formed in the respective welded portions on the outer cylinder 2 side, as in the welding inspection on the inner cylinder 1 side. Whether or not there is a defect such as a crack or undercut, and whether or not the throat thickness L1, bead height H1, penetration depth c, or the like is satisfied is checked and confirmed. If it is acceptable (step 115), the process proceeds to the step of the next process 125. If there is a rejected welded part, the process proceeds to the repair welding process 116 to repair weld the rejected welded part and the vicinity.

  As in the case of the inner cylinder 1 side, it is necessary to repair and weld (overlay repair) the welded defective part such as an excessive undercut, insufficient throat thickness or insufficient bead height generated in the welded part on the outer cylinder 2 side. . As shown in FIG. 10, in the inspection steps 114 and 120 on the outer cylinder 2 side, in order to perform the pass / fail determination of the welding quality, for example, the throat thickness L1 is L1 <T1, or the bead height H1 is H1 <T1, or under When the cut depth R is R> (0.1 × T1), it is judged as rejected (welding failure), and the welding failure part and its vicinity in the failing judgment are repaired in repair welding processes 116 and 122. carry out.

  As in the case of the inner cylinder 1 side, when repairing a defective weld portion determined to be rejected in the repair welding processes 116 and 122, the second welding on the outer cylinder 2 side including the temporary assembly process of each fillet joint. The TIG-MIG welding torch used in step 110 (main welding step) or the same or the same type of welding torch, welding wire and shield gas of the same component are used, respectively, and the temporary assembly process of each fillet joint is performed. The TIG-MIG welding torch or the MIG welding torch is run in the same direction as the welding direction at the time of construction in the second welding step 110 on the outer cylinder 2 side including, by combined welding or MIG welding of the preceding TIG and the subsequent MIG, Repair welding is performed on the poor welded part and its vicinity so as to build up the weld bead (welded cross-sectional part) 10-1 having the poor welded part, and the defective welded part disappears. And so as to form a weld bead 100-1.

  In addition, when repairing a defective welded part in the repair welding processes 116 and 122, as described above, the repair is substantially the same as the welding conditions used in the first welding process 110 including the temporary assembly process of each fillet joint. It is formed in the second welding process 110 on the outer tube 2 side including the temporary assembly process of each fillet joint using welding conditions or other repair welding conditions in which the MIG voltage and the heat input amount are increased from the repair welding conditions. The TIG-MIG welding torch or the MIG welding torch may be arranged on a line shifted by a predetermined distance from the toe end of the copper side of the repair weld bead 10-1 to the heat transfer copper fin 3 surface side.

  And a TIG-MIG welding torch or a MIG welding torch is run so as to pass on the line of the poorly welded part and the vicinity thereof, and a weld bead having a poorly welded part by combined welding of the preceding TIG and the succeeding MIG or MIG welding. (Welding cross section) 10-1 is repaired on the poorly welded part and its vicinity so as to build up from the top so that the poorly welded part disappears and a good repair weld bead 100-1 is formed. I am doing so.

  By repair welding in this way, defective welds such as a throat thickness L1 shortage or a bead height H1 shortage and an excessive undercut depth R can be reliably eliminated, and a repair weld bead 100-1 with good quality can be obtained. Can be obtained. Further, as described above, the production of the metal cask welded structure can be continued by the repair by the repair method.

  The repair locations to be repaired (built-up repair) are mainly welded defective portions and the vicinity thereof that have been determined to be rejected, and as described above, build-up from above the weld bead 10-1 having the welded defective portions. As described above, repair welding may be performed on the poorly welded portion and its vicinity. In addition, since it is not necessary to perform repair welding in the welding good part of a pass determination, it may be omitted.

  Then, in the quality inspections 1141 and 1201 of the repair welds that are performed after the repair is completed, the throat thickness L2 ≧ T1, the bead stack height H2 ≧ T1, and the undercut depth R ≦ (0.1 × T1) after repair are restored. It is determined to be acceptable and the process proceeds to the next step 125.

  As described above, even when a welding failure occurs in the welded portion on the outer tube 2 side, the throat thickness L1 is insufficient or the bead height H1 is insufficient and under, as in the case of the inner tube 2 side, by the original repair welding. Welding defects such as excessive cut depth R can be reliably eliminated, and repair weld bead 100-1 with good quality can be obtained, and a large weld throat thickness and heat conduction cross-sectional area contributing to improved heat removal performance can be secured. can do.

  FIG. 11 and FIG. 12 show one embodiment of a schematic configuration and a torch arrangement of an integrally structured TIG-MIG welding torch according to the present embodiment.

  As shown in FIG. 11, a TIG-MIG welding torch 11 having a monolithic structure has a non-consumable electrode 13 such as tungsten, and a first shield gas 14 directed toward the tip and the welded portion of the non-consumable electrode 13. A TIG unit 12 having a first gas passage (not shown) to be discharged, a consumable wire 18 (also referred to as a welding wire) such as a CuSi wire, a wire passage (not shown) through which the consumable wire 18 is inserted, A MIG unit 17 having a second gas passage for allowing the second shield gas 19 to flow out toward the distal end portion and the welding portion of the consumable wire 18 is provided.

  The first and second shield gases 14 and 19 can change the type and composition of the gas, but here, a mixed gas of Ar gas and He gas is used as the shield gas. By using a mixed gas of Ar gas and He gas for welding copper and steel, compared to pure Ar gas, the potential gradient is high, weldability and wettability are excellent, and the quality is good. It becomes easy to obtain a weld. Although not shown, a water channel for cooling the TIG-MIG welding torch 11 with circulating water is also provided.

  The TIG-MIG welding torch 11 is attached to the distal end portion of a long arm 31 that can move and move with respect to the weld line 6 of the fillet joint portion 5 between the steel inner tube 1 and the copper heat transfer copper fin 3. Attached in a substantially downward position via a jig (not shown), or attached to the tip of the long arm 31 via a mounting jig and a biaxial drive table (not shown) that can move left and right and up and down, and It arrange | positions in the welding line 6-1 direction.

  Further, an articulated movable welding robot is used instead of the long arm 31 that can be moved and moved, and the TIG-MIG welding torch 11 is arranged (attached) to the wrist of the welding robot, and the TIG-MIG welding torch is arranged. While moving 11, the composite welding of the preceding TIG and the subsequent MIG may be performed from the start position to the end position of the weld line of the fillet joint portion.

  Furthermore, the TIG unit 12 on the non-consumable electrode 13 side of the preceding TIG is inclined at a receding angle −α1 in the direction opposite to the welding progress direction, and the MIG unit 17 on the consumable wire 18 side of the subsequent MIG is welded. It is inclined in the direction with a forward angle + α2.

  The receding angle -α1 on the preceding TIG side is preferably in the range of 0 to 45 degrees. It is more preferable to arrange it in the range of 15 to 30 degrees. The forward angle + α2 on the other subsequent MIG side is preferably in the range of 15 to 45 degrees. It is more preferable to arrange it in the range of 15 to 30 degrees.

  The distance interval f1 between the electrodes from the position where the extension line of the tip of the non-consumable electrode 13 intersects the weld line 6 of the joint base material to the tip of the consumable wire 18 is preferably in the range of 3 to 9 mm. . It is even better if it is preferably placed in the range of 4-7 mm. The electrode height f2 from the weld line 6 of the joint base material to the tip of the non-consumable electrode 13 is preferably in the range of 3 to 9 mm. It is even better if it is preferably placed in the range of 4-7 mm.

  Thus, the composite welding of the preceding TIG and the subsequent MIG can be stably performed by arranging the TIG-MIG welding torch 11 and causing the traveling movement and the welding operation on the welding line.

  If the receding angle −α1 of the TIG unit 12 and the advancing angle + α2 of the MIG unit 17 are too smaller than 15 degrees, for example, the distance interval f1 between the non-consumable electrode 13 and the consumable wire 18 can be brought close to a predetermined range. In addition, the shape of one molten pool 24 formed by the TIG arc 22 and the MIG arc 23 tends to be elongated and unstable.

  On the other hand, if the receding angle −α1 and the advancing angle + α2 are too larger than the above-described angle range, the droplets of the consumable wire 18 melted by the MIG arc 23 are likely to be spattered and scattered in the direction of the preceding TIG. May adhere to the non-consumable electrode 13 on the preceding TIG side and damage the non-consumable electrode 13, and the gas shielding property is likely to deteriorate, which is not preferable.

  Therefore, the receding angle −α1 on the preceding TIG side is preferably in the range of 0 to 45 degrees, and the advancing angle + α2 on the subsequent MIG side is preferably in the range of 15 to 45 degrees.

  On the other hand, if the value of the distance interval f1 between the non-consumable electrode 13 and the consumable wire 18 is too smaller than 3 mm, for example, the TIG arc 22 and the MIG arc 23 are too close and spatter generated from the consumable wire 18 on the subsequent MIG side. May adhere to the non-consumable electrode 13 on the preceding TIG side and damage the non-consumable electrode 13, and the behavior of the TIG arc 22 and the MIG arc 23 is likely to be unstable.

  On the other hand, if the distance interval f1 between the non-consumable electrode 13 and the consumable wire 18 is too larger than 9 mm, the shape of one molten pool 24 formed by the TIG arc 22 and the MIG arc 23 tends to be elongated and unstable, and the desired distance A weld bead and a weld cross section may not be obtained.

  Accordingly, the distance interval f1 between the electrodes from the position where the extension line of the tip of the non-consumable electrode 13 intersects the weld line 6-1 of the joint base material to the tip of the consumable wire 18 is in the range of 3 to 9 mm. Good.

  Furthermore, if the electrode height f2 from the weld line 6 of the joint base material to the tip of the non-consumable electrode 13 is too smaller than 3 mm, for example, melting occurs due to a decrease in arc voltage and a decrease in heat input associated with the shortening of the TIG arc 22. Insufficiency may occur, and the tip of the non-consumable electrode 13 is close to the surface of the molten pool 24, so that it is easily affected by changes in behavior of the molten pool 24 and scattered spatter.

  On the other hand, if the electrode height f2 from the weld line 6-1 of the joint base material to the tip of the non-consumable electrode 13 is too larger than 9 mm, arc destabilization and increased heat input accompanying the extension of the TIG arc 22 The heat transfer copper fins 3 may be melted excessively, which may cause undercutting, and the gas shield property is likely to deteriorate, which is not preferable.

  Therefore, the electrode height f2 from the weld line 6-1 of the joint base material to the tip of the non-consumable electrode 13 is preferably in the range of 3 to 9 mm.

  As shown in FIG. 12, the TIG welding power source 15 is connected between the non-consumable electrode 13 in the TIG unit 12 and the inner cylinder 1 of the joint base material via power supply cables 16-1 and 16-2. In addition, with the polarity on the non-consumable electrode 13 side as the negative electrode (minus) and the polarity on the inner cylinder 1 side as the positive electrode (plus), the TIG arc 22 is generated at the welding location in the outflow atmosphere of the shield gas 14. The other MIG welding power source 20 (including the wire feeding device) is connected between the consumable wire 18 in the MIG unit 17 and the inner cylinder 1 of the joint base material via power supply cables 21-1 and 21-2. In addition, the polarity on the side of the consumable wire 18 to be fed and fed is positive (plus) and the polarity on the inner cylinder 1 side is negative (minus), and the MIG arc 23 in the outflow atmosphere of the second shield gas 19 Is generated near the rear of the TIG arc 22.

  The first welding current Ia flowing through the non-consumable electrode 13 on the preceding TIG side and the second welding current Ib flowing through the consumable wire 18 (CuSi wire) on the subsequent MIG side repel each other. Two molten TIG arcs 22 and MIG arcs 23 form one molten pool 24, and the main welding is performed while moving in the welding direction 25a so as to pass over the weld line 6 of the provisional joint joint.

  The ratio (Ia / Ib) between the first welding current Ia and the second welding current Ib is preferably set in the range of about 0.8 to 1.2. Further, both the first and second welding currents Ia and Ib are preferably supplied with direct current to form two arcs of direct current. .

  Welding current Ia between direct currents in the range of the ratio of the first welding current Ia flowing through the non-consumable electrode 13 and the second welding current Ib flowing through the consumable wire 18 (Ia / Ib = 0.8 to 1.2). By outputting Ib, the TIG arc 22 and the MIG arc 23 that repel each other are maintained in a state of being substantially deflected downward, and one molten pool 24 can be stably formed. In addition, the droplets from the tip of the consumable wire 18 do not scatter, and the droplets easily migrate into the molten pool 24 and have a good weld bead and weld cross section (weld cross section) 7. −1 can be obtained.

  When the ratio (Ia / Ib) between the first welding current Ia flowing through the non-consumable electrode 13 and the second welding current Ib flowing through the consumable wire 18 is too small or too large, they repel each other. Since a large deviation occurs between the matching TIG arc 22 and MIG arc 23, the arc behavior on the smaller current side becomes unstable due to the influence of the arc force on the larger current side, which tends to cause poor welding.

  On the other hand, for example, when the polarity on the TIG side is reversed from the negative electrode (minus) to the positive electrode (plus), the non-consumable electrode 13 such as tungsten is consumed violently due to high temperature overheating during welding, so that the arc behavior is unstable. This tends to cause poor welding and makes it difficult to weld for a long time. In addition, since the TIG arc 22 and the MIG arc 23 are deflected in a mutually attracting direction, droplets of the MIG side consumable wire 18 are welded to the non-consumable electrode 13 on the TIG side, and electrode consumption occurs in a short time. There is also. If the polarity of the other MIG side is reversed from the positive electrode (plus) to the negative electrode (minus), unstable arc behavior and spatter are likely to cause poor welding, making it difficult to weld for a long time. .

  In FIG. 12, for ease of explanation, a TIG arc 22 and a MIG arc 23 and one molten pool 24 are shown on the weld line 6 near the center, but the TIG arc 22 and the MIG arc 23 are actually shown. The location to be generated is a welding start position on the weld line 6 of the fillet joint portion 5 to be welded.

  For example, after rotating the joint (inner cylinder 1 and heat transfer copper fin 3) side to be welded with a rotary drive device or the like and changing the posture of the weld line 6 of the fillet joint portion 5 to be welded in the vertical direction, The integrally structured TIG-MIG welding torch 11 is positioned on the welding line 6-1 in a downward posture. Thereafter, the TIG-MIG welding torch 11 is stopped at the welding start position on the welding line 6. While flowing the mixed gas of Ar gas and He gas from both the front end opening of the TIG unit 12 in the TIG-MIG welding torch 11 and the front end opening of the MIG unit 17 at and near the welding start position, Immediately after the first negative electrode (minus) TIG arc 22 is generated from the tip of the non-consumable electrode 13 of the TIG and the first welding current Ia reaches the steady value or after a predetermined time has elapsed, the consumable wire 18 of the subsequent MIG A positive electrode (positive) MIG arc 23 is generated from the CuSi wire to be fed in the vicinity of the rear of the TIG arc 22 and the second welding current Ib reaches a steady value to repel each other. 22 and the MIG arc 23 form one molten pool 24 and immediately after the welding start position is generated or after a predetermined time has elapsed, TIG- The MIG welding torch 11 is caused to travel so as to weld to the welding end position of the fillet joint portion 5 while moving one molten pool 24 in the welding line direction.

  By performing welding in this way, as described above, a good weld bead (welded cross section) 7-1 is reliably formed on the weld line 6 from the welding start position to the end position of the fillet joint 5. be able to.

  FIG. 13 shows an example of a schematic configuration and a torch arrangement of a MIG welding torch as Embodiment 2 of the present invention. The example shown in the figure is an example in the case where MIG welding is performed using the MIG welding torch 26 instead of the TIG-MIG welding torch 11 described above.

  As shown in the figure, when the MIG welding torch 26 is used, the MIG is connected between the CuSi wire of the consumable wire 18 and the inner cylinder 1 of the joint base material via the feeding cables 29-1 and 29-2. A welding power source 28 is connected. Further, the MIG welding torch 26 is, as in the case of the TIG-MIG welding torch 11 described above, a distal end portion or a multi-joint of a long arm (not shown) that can move and move with respect to the welding line 6 to be welded. It is attached to the wrist of a movable welding robot (not shown) in a substantially downward position via an attachment jig (not shown), and is arranged in the direction of the welding line 6.

  Further, the MIG welding torch 26 in the present embodiment is disposed so as to be substantially perpendicular to the welding direction or inclined at an advance angle + α3. The advance angle + α3 is preferably in the range of 0 to 30 degrees. It is more preferable to arrange it in the range of 0 to 15 degrees.

  Although the advance angle + α3 is omitted, it is a torch inclination angle corresponding to the inclination angle + α2 of the MIG unit 17 in the TIG-MIG welding torch 11 shown in FIGS. 11 and 12, and shown in FIG. When the MIG welding torch 26 is used, the advance angle + α3 is preferably set in the range of 0 to 30 degrees. It is more preferable to arrange it in the range of 0 to 15 degrees.

  If welding is performed with the advance angle + α3 larger than 30 degrees, the MIG arc 23 is inclined too far forward, so that the droplets of the consumable wire 18 melted by the MIG arc 23 are likely to scatter forward (occurrence of spatter frequently). In addition, the gas shield property is liable to be lowered, which is not preferable.

  When performing MIG welding in the first welding process 103 on the inner cylinder 1 side including the temporary assembly process of each fillet joint and the second welding process 110 on the outer cylinder 2 side including the temporary assembly process of each fillet joint The electrode polarity of the consumable wire 18 to be fed and fed from the MIG welding power source 28 side while flowing the MIG shield gas 27 made of a mixed gas of Ar gas and He gas from the tip opening of the MIG welding torch 26. A MIG arc (not shown) having a positive electrode (plus) is generated from the welding start position on the weld line 6 of the fillet joint 5 to form one molten pool 24 by one arc, and then the MIG welding torch. It is made to weld in a downward attitude | position, moving 26 to a welding direction.

  Welding with a DC MIG arc that feeds a positive (positive) DC current to the consumable wire 18 is also possible, but using a pulsed MIG arc that alternately repeats a high peak current and a low base current is more effective than with a DC MIG arc. Also, welding with less spatter generation can be performed.

  The angle θ1 between one end surface portion of the heat transfer copper fin 3 on the inner tube 1 side to be welded and the fillet joint portion 5 or the other end surface portion of the heat transfer copper fin 3 on the outer tube 2 side and the fillet joint portion 8 is θ1. = 120 ° ± 15 ° (105 ≦ θ1 ≦ 135 °) wide angle inclination (configuration), and both of the heat transfer copper fins 3 formed on both surfaces of the inner cylinder 1 and the outer cylinder 2 The angle θ1 of the fillet joint portion 5 with the end face portion is also preferably arranged within the same range as the above value. Further, the inclination angle θ2 on the other inner cylinder 1 side or outer cylinder 2 side is arranged to be in a range of θ2 = 30 degrees ± 15 degrees (15 ≦ θ2 ≦ 45 degrees) with respect to the horizontal line.

  The joint member (the heat transfer copper fin 3 and the inner cylinder 1 or the heat transfer fin 3 and the outer cylinder 2) is inclined in such an angle range, so that the same applies to the MIG welding torch 26 (TIG-MIG welding torch 11). ) Can be arranged in a substantially vertical downward position, the operability of the welding torch and the like is improved, and preparatory work and welding work before welding can be improved.

  As described with reference to FIGS. 1 and 2, each space portion 4 divided between the inner cylinder 1 and the outer cylinder 2 and a plurality of (N) heat transfer copper fins 3 includes the spent fuel. A substance (resin) that shields radiation emitted from the aggregate in a normal line is filled in a resin filling step that is performed separately.

  Therefore, as shown in FIGS. 5 and 8, when the angle θ1 of the fillet joint portions 5 and 8 to be welded is larger than 135 degrees, radiation can be effectively shielded by the above-described resin filling. However, since it is necessary to make the plate width of each heat transfer copper fin 3 to be welded between the outer surface of the inner tube 1 and the inner surface of the outer tube 2 at the time of welding, it is possible to manufacture the heat transfer copper fins 3. There is a high possibility that a part of the welding torch comes into contact with the adjacent heat transfer copper fin 3 and the welding work cannot be carried out when the adjacent heat transfer copper fins 3 are welded together with an increase in cost.

  On the other hand, if the angle θ1 of the fillet joint portions 5 and 8 is smaller than 105 degrees, the plate width of the heat transfer copper fins 3 can be reduced and welding can be easily performed, but it is released from the spent fuel assembly. It is anticipated that a part of the radiation dose will be transmitted from between the resins (the heat transfer copper fins 3 and the gaps). .

  Therefore, by arranging the angle θ1 of the fillet joint portions 5 and 8 at a wide-angle inclination in the range of 105 ≦ θ1 ≦ 135 degrees, it is possible to perform the welding work and ensure the radiation shielding ability.

  Further, the inclination angle θ2 on the inner cylinder 1 side or the outer cylinder 2 side is an angle for disposing the MIG welding torch 26 (the same applies to the TIG-MIG welding torch 11) in a substantially vertical downward posture. For example, when the angle θ1 of the fillet joints 5 and 8 is reduced, the other inner cylinder 1 side or the outer cylinder 2 may be changed. In the case of changing the inclination angle θ2 on the side to increase the angle and conversely increasing the angle θ1 of the fillet joint portions 5 and 8, it is preferable to change the inclination angle θ2 to decrease.

  The integrated TIG-MIG welding torch 11 and the MIG welding torch 26 dedicated to MIG welding shown in FIGS. 11, 12, and 13 can be moved and moved by an arm driving device 31-1, as shown as an example in FIG. It is attached to the tip of the long arm 31 (or the wrist of the articulated movable welding robot) in a substantially downward position via an attachment jig, or the attachment jig and the left / right / up / down movement to the tip of the long arm 31 It is mounted in a substantially downward posture via a possible two-axis drive table and is arranged in the weld line direction.

  Moreover, from the welding start position of the weld line of the fillet joint part to be welded for each pass to the copper plate of the heat transfer copper fin 3 and the steel material of the inner cylinder 1 or the outer cylinder 2 and the fillet joint part, to the end position, The traveling operation and welding operation of the integrally structured TIG-MIG welding torch 11 or MIG welding torch 26 according to the traveling command of the long arm 31 by the welding control device 20-1 and the output commands to the TIG welding power source 15 and the MIG welding power source 20. , Welding is performed from the start position to the end position of the weld line of the fillet joint portion by performing composite welding of the preceding TIG and the subsequent MIG or MIG welding.

  In this manner, the MIG welding torch 26 or the TIG-MIG welding torch 11 is disposed downward on the weld line 6 of the fillet joint portion 5 having the inclined joint, thereby completing the welding line from the start position of the weld line. While being able to weld stably to a position, it becomes possible to obtain a favorable weld bead and a weld cross section.

  As described above, the welding line 6 is a position obtained by shifting the wire position or torch position (including the electrode position) from the end face corner portion to the surface side of the heat transfer copper fin 3 by a predetermined distance, and the shift amount S1 (the first amount) 1 distance S1) is preferably set in a range of S1 = 0 to 4 mm (0 ≦ S1 ≦ 4 mm). Preferably, it is considered better if the range is 1 ≦ S1 ≦ 3 mm.

  If the shift amount S1 is too smaller than 0 mm, the wire position or the torch position is closer to the steel side, so that the arc and the molten pool during welding are formed closer to the steel side. However, the throat thickness L1 and the bead height H1 decrease due to insufficient melting on the opposite copper side (heat transfer copper fin side). If the influence is excessive, the throat thickness is insufficient or There is a high possibility that the bead height will be insufficient.

  On the other hand, if the shift amount S1 is larger than 4 mm, the welding arc and the molten pool are likely to be formed closer to the heat transfer copper fin side, so that the weld throat thickness L1 and the bead height H1 are likely to increase. There is a high possibility that the hot copper fins will melt down due to overmelting, or that the opposite steel side will be poorly fused (insufficient strength).

  Moreover, about the shape of the both-ends surface part of the heat-transfer copper fin 3 (length direction shortening), as shown in FIG. 13, with respect to the surface of the heat-transfer copper fin 3, the flat surface of the substantially orthogonal end surface without an inclined surface Although it is the shape 39, the heat transfer copper fin 3 of the inclined surface shape inclined in the range of 30 degree +/- 15 degree can also be used. When both end portions of the heat transfer copper fin 3 have a flat surface shape 39, a gap or the like is likely to be generated due to the opening of the bottom surface of the joint, but the processing cost is reduced as compared with the case of the heat transfer copper fin 3 having an inclined surface shape. be able to.

  FIG. 14 shows an example of a schematic configuration of a TIG-MIG welding torch according to Example 3 of the present invention and a torch arrangement for TIG-MIG repair welding so as to build up from above the weld bead portion.

  A welding torch 11A used for repair welding in the present embodiment includes a first welding process 103 on the inner cylinder 1 side including a temporary assembly process for each fillet joint, and an outer cylinder 2 side including a temporary assembly process for each fillet joint. The TIG-MIG welding torch used in the second welding step 110 is the same as or the same type as the welding torch, and is disposed so as to pass over the weld line 60 to be repaired.

  The weld line 60 to be repaired is shifted by a predetermined distance from the bead toe 7b on the heat transfer copper fin 3 side of the inner weld 7 having the poor weld to be repaired to the surface side of the heat transfer copper fin 3. It is a position, and the shift amount S2 (second distance) is preferably set in a range of 0 to 3 mm (0 ≦ S2 ≦ 3 mm). Preferably, it is better to limit to the range of 1 ≦ S2 ≦ 2 mm.

  Further, the welding wire 18 and shield gas 14 and 19 used for this TIG-MIG repair welding are used for the first welding process 103 on the inner cylinder 1 side including the temporary assembly process of each fillet joint, and for each fillet joint. SiCu wire of the same component as that used in the second welding process 110 on the outer cylinder 2 side including the temporary assembly process, a mixed gas of Ar gas and He gas, and further, a TIG welding power source 15 and a wire feeding device It is preferable to use the same MIG welding power source 20 including

  As described above, the first welding process 103 on the inner cylinder 1 side including the temporary assembly process of each fillet joint, the second welding process 110 on the outer cylinder 2 side including the temporary assembly process of each fillet joint, and repair welding. By sharing the apparatus used in Steps 109, 116, 119, and 122, it is possible to reduce capital investment and manufacturing cost.

  In the above-described repair welding processes 109, 116, 119 and 122, when TIG-MIG repair welding is performed on a welded defective part such as an excessive undercut depth or insufficient throat thickness, the provisional assembly process for each fillet joint is included. From repair welding conditions or repair welding conditions substantially the same as those used in the first welding process 103 on the cylinder 1 side and the second welding process 110 on the outer cylinder 2 side including the temporary assembly process of each fillet joint In addition, using other repair welding conditions with increased MIG voltage and heat input, the first welding process 103 on the inner cylinder 1 side including the temporary assembly process of each fillet joint, and the temporary assembly process of each fillet joint are included. A position shifted by a predetermined distance from the bead toe portion 7b on the heat transfer copper fin 3 side of the weld bead portion 7 formed in the second welding step 110 on the outer cylinder 2 side to the surface side of the heat transfer copper fin 3 ( 0 ≦ S2 ≦ 3 mm) on the weld line 60 to be repaired. The torch 11 is disposed, and the TIG-MIG welding torch 11 is caused to travel so as to pass over the weld line 60 to be repaired at least in the defective weld portion to be repaired and in the vicinity thereof, and by the composite welding of the preceding TIG and the subsequent MIG Then, repair welding is performed on the welded defective part and its vicinity so as to build up from the inner welded part 7 having the welded defective part, and the welded defective part disappears and a good repair weld bead (welded cross section). Part) 70 is formed.

  For example, the polarity of the non-consumable electrode 13 in the TIG unit 12 is set to the negative electrode (minus), the polarity on the inner cylinder 1 side is set to the positive electrode (plus), and the TIG arc 22 is generated in the weld bead 7-1 and the vicinity. The polarity of the consumable wire 18 to be fed and fed from the other MIG unit 17 side is positive (plus), the polarity of the inner cylinder 1 side is negative (minus), and the MIG arc 23 is near the rear of the TIG arc 22. generate.

  Then, the TIG arc 22 and the MIG arc 23 that repel each other form one molten pool 24 and pass through the weld line 60 to be repaired at least in the defective weld portion to be repaired and the vicinity thereof. -The MIG welding torch 11 is made to travel in the repair direction 25b of the preceding TIG and the subsequent MIG, and the TIG-MIG repair welding using the TIG arc 22 and the MIG arc 23 is used to build up the weld bead portion 7 having a poor weld portion. Then, repair welding is performed to eliminate defective welds and form a good repair weld bead 70.

  By repairing TIG-MIG in this way, defective welds such as lack of throat thickness L1 or bead height H1 and excessive undercut depth R can be reliably eliminated, and repair with good quality is possible. A bead and repair weld cross section (repair bead) 70 can be obtained.

  FIG. 15 shows an example of a schematic configuration of a TIG-MIG welding torch according to Example 4 of the present invention and an example of a torch arrangement for TIG repair welding so as to build up from above the weld bead portion.

  The main difference from FIG. 14 is that the MIG arc 23 is not generated, only the TIG arc 22 is generated, and the consumable wire 18 (welding wire) that is a cold wire without power supply from the MIG unit 17 side is replaced with the TIG arc. 22 and in the molten pool 24, TIG repair welding is performed while feeding at a lower speed than the wire speed used in TIG and MIG welding.

  Note that the apparatus configuration of the TIG-MIG welding torch 11, the SiCu wire (consumable wire 18), the mixed gas of Ar and He, the TIG welding power source 15 and the MIG welding power source 20 used for this TIG repair welding is each fillet. The apparatus configuration used in the first welding process 103 on the inner cylinder 1 side including the temporary assembly process of the joint and the second welding process 110 on the outer cylinder 2 side including the temporary assembly process of each fillet joint (FIGS. 11 and FIG. It is the same as 12).

  In the repair welding processes 109, 116, 119 and 122 described above, when TIG repair welding is performed using the TIG-MIG welding torch 11, for example, Ar and He from the tip openings of the TIG unit 12 and the MIG unit 17. The TIG arc 22 is welded with the polarity of the non-consumable electrode 13 in the TIG unit 12 being negative (minus) and the polarity on the inner cylinder 1 side being positive (plus). A wire used in TIG and MIG welding in the TIG arc 22 and in the molten pool 24 is a consumable wire 18 that is generated near the bead portion 7 and in the vicinity thereof, and then has no power supply (no MIG arc) from the other MIG unit 17 side. A low-speed feed at a speed slower than the speed causes one TIG arc 22 to form one melt pool 24, and a weld defect to be repaired. The TIG-MIG welding torch 11 travels in the repair direction 25b of the preceding wire and the subsequent TIG arc 22 so as to pass over the welding line 60 to be repaired in the vicinity thereof, and one TIG arc 22 and one molten pool 24 are passed. By performing TIG repair welding by forming the weld bead 7 having a defective weld portion, repair welding is performed so that the defective weld portion is eliminated and a good repair weld bead 70 is formed. ing.

  When the TIG-MIG welding torch 11 is run in the direction opposite to the repair direction 25b of the preceding wire and the subsequent TIG arc 22, and the TIG repair is performed, the rear of the TIG arc 22 having a receding angle (the arc shape of the backward curve) Since the wire is fed into the TIG arc 22 and into the molten pool 24, unstable wire melting and formation of the molten pool 24 tend to cause defective beads.

  For this reason, by moving the TIG-MIG welding torch 11 in the direction of the preceding wire and the subsequent TIG arc 22 and repairing the TIG, the wire is moved from the front of the TIG arc 22 of the advance angle (the arc shape of the forward bending) to the TIG. Since it is fed into the arc 22 and into the molten pool 24, the wire is smoothly melted and the molten pool can be formed stably, and a good repair weld bead can be obtained.

  In addition, it is also possible to change to perform TIG repair welding using a TIG dedicated torch instead of the TIG-MIG welding torch 11.

  In this way, TIG repair welding can reliably eliminate defective welds such as lack of throat thickness L1 or bead height H1 and excessive undercut depth R, and repair welding with good quality. A bead (repair cross section) 70 can be obtained.

  The welding line 60 to be TIG repair welded is the same as in the case of TIG-MIG repair welding, and the heat transfer copper fin 3 is connected to the heat transfer copper fin 3 from the bead toe 7b on the heat transfer copper fin 3 side of the weld bead 7 having a poorly welded portion. The position is shifted to the surface side by a predetermined distance S2, and the shift amount S2 (second distance) may be set in a range of 0 to 3 mm (0 ≦ S2 ≦ 3 mm), preferably 1 ≦ S2 ≦. A range of 2 mm is even better.

  The repair welding conditions used for TIG repair welding are, for example, the first welding process 103 on the inner cylinder 1 side including the temporary assembly process of each fillet joint, and the outer cylinder 2 including the temporary assembly process of each fillet joint. A TIG current equal to or greater than the TIG current used (output) in the second welding step 110 on the side is set, and the welding (repair) speed V is in the range of 90 to 150 mm / min (90 ≦ V ≦ 150 mm / min) It is preferable to increase the heat input amount by setting and to feed the consumable wire 18 without power supply at a low speed (for example, 2 to 2.5 m / min) at a speed slower than the wire speed used in TIG and MIG welding.

  The TIG-MIG welding torch 11 is moved in the repair direction 25b of the preceding wire and the subsequent TIG arc 22 so as to pass over the welding line 60 to be repaired with the shift amount S2, and TIG repair welding is performed using repair welding conditions. As described above, it is possible to surely eliminate defective welds such as a lack of throat thickness L1 or a bead height H1 and an excessive undercut depth R, and repair weld beads with good quality (repairs) Welded cross section) 70 can be obtained.

  FIG. 16 shows an example of a schematic configuration of a MIG welding torch according to the fifth embodiment of the present invention and a torch arrangement for performing MIG repair welding so as to build up from above the weld bead portion. The example shown in the figure is an example in the case of using the MIG welding torch 26 instead of the TIG-MIG welding torch 11 described above, and is the same as the apparatus configuration of MIG welding shown in FIG.

  As shown in FIG. 16, when MIG repair welding is performed using the MIG welding torch 26 in the repair welding processes 109, 116, 119 and 122, the inner cylinder 1 side including the temporary assembly process of each fillet joint is performed. 1, the same or the same kind of MIG welding torch 26 used in the second welding step 110 on the outer tube 2 side including the temporary assembly step of each fillet joint, and the consumable wire 18 of the same component ( (SiCu wire) and shield gas 27 (mixed gas of Ar and He) are used, and the first welding process 103 on the inner cylinder 1 side including the temporary assembly process of each fillet joint, A weld bead portion having a poorly welded portion by running the MIG welding torch 26 in the same direction as the welding direction in the second welding step 110 on the outer cylinder 2 side including the assembly step, and by MIG welding with the MIG arc 23 Above 7 As a result, MIG repair welding is performed so as to build up, and the defective weld portion is eliminated, and a good repair weld cross section (weld bead) 70 can be formed.

  For example, the electrode polarity of the consumable wire 18 to be fed and fed from the MIG welding power source 28 side while the MIG shielding gas 27 made of a mixed gas of Ar gas and He gas is allowed to flow out from the tip opening of the MIG welding torch 26. A positive (plus) MIG arc is generated in the weld bead portion 7 and the vicinity thereof, and one molten pool 24 is formed by one MIG arc 23 and passes over the weld line 60 in the poor weld portion and the vicinity thereof. The MIG welding torch 26 is caused to travel in the repair direction 25b so that MIG welding is performed by forming one MIG arc 23 and one molten pool 24 so as to build up from the top of the weld bead portion 7 having a poorly welded portion. While repair welding is performed to eliminate the defective welded portion, a good repair weld bead (welded cross section) 70 can be formed. That.

  By repairing the MIG in this way, as described above, it is possible to reliably eliminate defective welds such as a lack of the throat thickness L1 or an insufficient bead height H1 and an excessive undercut depth R. A good repair weld bead (weld cross section) 70 can be obtained.

  Further, the MIG welding torch 26 is shifted from the bead toe 7b of the weld bead 7 having a poor weld portion to the surface side of the heat transfer copper fin 3, and the shift amount S2 (second distance) is TIG-MIG repair. As in the case of welding, as described above, the range may be 0 mm or more and 3 mm or less (0 ≦ S2 ≦ 3 mm), and more preferably 1 ≦ S2 ≦ 2 mm.

  Further, when repairing a defective weld and its vicinity in the repair welding processes 109, 116, 119 and 122, the first welding process 103 on the inner cylinder 1 side including the temporary assembly process of each fillet joint, Repair welding conditions that are substantially the same as the welding conditions used in the second welding process 110 on the outer cylinder 2 side including the temporary assembly process of each fillet joint, or the MIG voltage and the heat input amount are increased more than the repair welding conditions. Repair welding using the repair welding conditions of

  As described above, the MIG welding torch 11 is caused to travel in the repair direction 25b so as to pass over the welding line 60 to be repaired with the shift amount S2 described above, and as described above, the MIG repair welding is performed using repair welding conditions. It is possible to surely eliminate defective welds such as insufficient thickness L1 or insufficient bead height H1 and excessive undercut depth R, and a repair weld bead (welded cross section) 70 with good quality can be obtained. .

  Next, methods and results of welding tests and repair tests actually conducted by the inventors will be described.

  FIG. 17 is an example showing a repair test method according to Example 6 of the present invention and a torch arrangement for repair welding so as to build up from above the weld bead portion.

  In this embodiment, a multi-joint movable welding robot 33 is used, and a fillet joint between a heat transfer copper fin (copper plate) 3 and an inner cylinder (steel plate) 1 which is inclinedly disposed on the work table 36 and the test fixing table 35. Then, a test for repair welding was carried out by placing a TIG-MIG welding torch held on the wrist 34 of the welding robot 33 in a vertically downward direction above the weld bead 7 welded in advance.

  FIG. 18 is a perspective view showing an embodiment of a TIG repair test piece for a welded simulated defect portion according to Embodiment 6 of the present invention.

  The test piece for TIG repair in this example is a copper plate having a thickness of 5 mm (material: C1020P, size: length 250 × width 80 mm) and a carbon steel plate having a thickness of 16 mm (material: SM400A, size: length 250 × A fillet joint with a width of 100 mm) was used. The wire was a 1.2 mm diameter CuSi wire (MG960), and the shielding gas was a mixed gas of Ar gas and He gas (50 to 70%).

  Then, the TIG-MIG composite welding of the main welding was preliminarily applied to the test piece of the fillet joint to form the main welding bead, and it was assumed that the test piece had a welding defect with insufficient throat thickness or excessive undercut depth.

  In the TIG repair welding test of the simulated defect portion, as shown in FIGS. 15 and 18, the TIG-MIG welding torch 11 is arranged and traveled above the weld bead 7 (simulated defect portion), and the preceding wire and the subsequent TIG arc are run. TIG repair welding by 22 was applied, and repair weld cross sections (repair weld beads 70) (one pass or two passes) having a length of about 50 mm were formed in two places. In this TIG repair welding test, in order to investigate appropriate repair welding conditions, the condition factors such as the torch position shift amount S2, the welding (repair) speed V, the wire feed speed Wf, and the TIG current It were changed.

  FIG. 19: is a perspective view which shows one Example of the TIG-MIG repair test piece of the welding simulation defect part concerning Example 6 of this invention.

  The test piece for TIG-MIG repair in this example is of the same material and size as the test piece for TIG repair, and the TIG-MIG composite welding of the main welding is previously applied to this copper / steel fillet joint. This was assumed to be a test piece having a weld defect with a short throat thickness or an excessive undercut depth.

  In the TIG-MIG repair welding test of the simulated defect portion, as shown in FIGS. 14 and 19, the TIG-MIG welding torch 11 is disposed and traveled above the weld bead 7 (simulated defect portion), and the preceding TIG TIG-MIG repair welding using an arc and subsequent MIG arc was performed, and a repair weld bead 70 having a length of about 160 mm was formed in one place. In this TIG-MIG repair welding test, the condition factors such as the MIG set voltage Em were changed.

  Table 1 shows the welds when the TIG-MIG composite welding test of the main welding is performed on the fillet joint specimen of the copper plate and the carbon steel and the TIG repair welding test and the TIG-MIG repair welding test are performed on the main welding bead. This shows the conditions and repair welding conditions.

  The TIG-MIG combined welding test of the main welding is a test for forming a weld bead 7 having a simulated defect that assumes a defective weld portion such as an excessive undercut or insufficient throat thickness before repair welding. TIG-MIG composite welding was performed under constant conditions of a speed of 354 mm / min, a wire feed speed of 11 m / min, and a TIG current of about 300A.

  In this TIG-MIG combined welding test, in order to investigate the influence on the welding quality such as the throat thickness L1 and the bead height H1, the welding operation is performed by changing the preheating of the joint specimen, the electrode height h and the shift amount S1. Then, a weld bead portion 7 having a simulated defect was formed and evaluated.

  On the other hand, in the TIG repair welding test that builds up on the weld bead 7 of the simulated defect, the TIG current (It = 275 to 340 A), the wire feed speed (Wf = 2 to 2.5 m / min), the repair welding speed (V = 90-120 mm / min), shift amount (S2 = 0-3 mm) and other conditional factors are changed, and as shown in FIG. 18, 1-pass repair or 2-pass repair is performed on the weld bead 7 to repair. The weld bead portion 70 was formed and evaluated.

  Moreover, in the TIG-MIG repair welding test that builds up on the weld bead 7 of the simulated defect, the repair welding conditions substantially the same as the main welding conditions are used, and the MIG set voltage is further increased, as shown in FIG. Then, one-pass repair was performed on the weld bead 7, and a repair weld bead portion 70 was formed for evaluation.

  The MIG setting voltage Em described in Table 1 is a voltage value measured between the MIG electrode and the base material because it is a voltage value on the MIG side (corresponding to the output voltage of voltage detection feedback control) including the power supply cable voltage. It is about 1.7-2V higher than (measured value).

  Further, the numbers on the left side of Table 1 (the same applies to Table 2 to be described later) are the test number for main welding (39-49) and the test number for repair (1-14). For example, the main welding 39 is listed at the top of Table 1 and the repairs 1 and 2 are described below because the tests for repairs 1 and 2 were performed on the weld bead after the test of the main welding 39. The same applies to the following number sequences. Furthermore, the reverse direction described in the column for the tacking direction in Table 1 is an expression for the welding direction, a test example in which TIG repair welding is performed in the direction of the wire preceding and following TIG arc, and the positive direction is also an expression for the welding direction. As in the case of the main welding, this is a test example in which TIG-MIG repair welding is performed in the direction of the preceding TIG arc and the subsequent MIG arc.

  Table 2 shows the shape dimensions and evaluation results of the TIG-MIG composite weld, TIG repair weld, and TIG-MIG repair weld when tested under the welding conditions and repair welding conditions shown in Table 1.

  In Table 2, the values of throat thickness L, bead stacking height H of each welded cross section taken from each welded test piece, and the results of poor fusion, bead appearance quality, and pass / fail evaluation are shown. Yes. The throat thickness L1 of the main welded part before repair satisfies all the reference values (L1 ≧ T1), but it is assumed that the weld bead has a simulated defect, and the repair bead part is placed on the weld bead part having the simulated defect. The throat thickness L2 and the bead stacking height H2 were measured and evaluated from each repair weld cross section after completion of repair.

  The hatched portion in Table 2 is a failure due to the determination due to excessive undercutting, poor melting, and burn-off, and a circle indicates that the quality standard is determined to be acceptable. For the Δ mark, the quality standard was satisfied, but the shape of the repair bead was inferior due to the effect of instability of the wire melting, and the mark was not reached.

  FIG. 20 is a characteristic diagram showing a cross-sectional area of wire welding when the welding (repair) speed and the wire feed speed according to Example 6 of the present invention are changed. In the figure, the application range of TIG repair welding and a photograph of a typical repair weld cross section are shown.

  As can be seen from the photograph of the repair weld cross section in the figure, the upper repair weld is deeply melted and fused into both the copper plate side and the lower weld. The wire welding cross-sectional area B increases in proportion to the wire feed speed Wf and is inversely proportional to the welding speed V.

  Applicable range of appropriate TIG repair welding for obtaining a good repair weld bead 70 is a welding (repair) speed V in a range of 90 ≦ V ≦ 150 mm / min and a wire feed speed Wf of 2 ≦ Wf ≦ 2. 5 m / min, preferably 2 ≦ Wf ≦ 2.2 m / min.

  By applying TIG repair welding in this application range, it is possible to reliably eliminate defective welds such as excessive undercut depth and insufficient throat thickness, and to obtain repair weld beads (repair weld cross sections) with good quality. it can.

  Note that if the welding (repair) speed V is faster than 150 mm / min, a defective bead tends to be formed due to the influence of insufficient heat input and insufficient cross section of the wire weld. On the other hand, if the wire feed speed Wf is less than 2 m / min, the melted state of the wire and the formation state of the melt pool become unstable at the time of repair welding due to the lack of the cross section of the wire weld, and a defective bead tends to be formed.

  On the other hand, if the repair speed V is slower than 90 mm / min, the production efficiency decreases due to an increase in work time, and the repair bead to be built up due to the effects of increased heat input and increased wire weld cross section is a weld bead on the steel side. It becomes easy to hang down. Also, if the wire feed speed Wf is more than 2.5 m / min, the wire welding cross section increases, but the throat thickness is unlikely to increase, and the repair bead becomes a weld bead on the steel side due to destabilization of wire melting. It becomes easy to hang down.

  Therefore, a good repair weld bead can be stably formed by performing TIG repair welding in the above-described application range.

  FIG. 21 is a test result showing an example of the weld cross section of the repair bead and the repair presence / absence portion when the TIG repair welding is performed from above the main weld bead after the TIG-MIG composite welding according to the sixth embodiment of the present invention. FIG.

  The numbers described in the bead appearance photograph in the figure are the test numbers shown in Tables 1 and 2. In addition, each weld (repair) cross-sectional portion indicates a position taken from one and two repair bead portions of the main weld bead portion. The welding speed of the main welding bead subjected to TIG-MIG composite welding is 354 mm / min, and the welding (repairing) speed of the repair bead repaired by TIG is 90 mm / min and 120 mm / min.

  As can be seen from the photograph of the repair weld cross section in the figure, the upper repair weld is deeply melted and fused into both the copper plate side and the lower weld.

  In this way, by performing TIG repair welding from above the weld bead 7, it is possible to surely eliminate defective welds such as excessive undercut depth and insufficient throat thickness, and repair weld beads with good quality (repair weld cross section). Part) 70 can be obtained. Moreover, manufacture of a metal cask welded structure can be continued by applying the main welding method by TIG-MIG composite welding and the repair method by TIG repair welding to the production line of a metal cask welded structure.

  In TIG repair welding, the welding (repair) speed is slower than in the case of TIG-MIG composite welding of main welding. For this reason, for example, the time of repair work can be shortened by applying TIG repair welding to a weld line in which the length of a defective weld portion to be repaired is relatively short.

  FIGS. 22 and 23 show the amount of shift of the torch position when TIG repair welding or TIG-MIG repair welding is performed on the main weld bead after TIG-MIG composite welding according to Example 6 of the present invention and before and after the repair. It is a characteristic view of one Example which shows the relationship between throat thickness and bead lamination | stacking height.

  As shown in FIG. 22, the throat thickness L1 of the main weld before repair is 6.4 to 6.7 mm and satisfies the reference value (L1 ≧ T1), but from above the weld bead 7. The throat thickness L2 when TIG repair welding is performed by changing the shift amount S2 (second distance) (S2 = 0 to 3 mm) has a variation of about 9.2 to 9.8 mm (about 1). .4 times). In the case of TIG-MIG repair welding, the thickness is 10.5 to 10.9 mm, which is larger than the throat thickness L2 of the TIG repair weld.

  On the other hand, the bead stacking height H2 tends to increase as the shift amount S2 increases as shown in FIG. While the bead height H1 before repair is about 6.7 to 6.8 mm, the bead stacking height H2 when repair welding is performed with the shift amount S2 set to 2 mm varies, The size is increased to 12.1 to 12.9 mm (about 1.8 to 1.9 times).

  From these results, for example, the repair welding described above is performed even when the values of the throat thickness L1 and the bead height H1 before repair are about 4 mm below the reference values (L1 ≧ T1 = 5, H1 ≧ T1). By doing so, the size can be improved to satisfy the reference value. In addition, even when the undercut depth is around 1 mm, the undercut can be reliably eliminated by applying repair welding so that the undercut portion and its vicinity are built up, and the reference value is satisfied. A good repair weld bead (repair weld cross section) having a throat thickness L2 and a bead lamination height H2 can be formed.

  If the shift amount S2 is too larger than 3 mm, the arc and molten pool during repair are likely to be formed closer to the copper side (heat transfer copper fin side), so the bead stacking height H2 may increase. The increase in the throat thickness L2 cannot be expected, and there is a high possibility that the heat transfer copper fin will be melted down. On the other hand, if the shift amount S2 is less than 0 mm, the arc and the molten pool at the time of repair are likely to be formed closer to the weld bead, so the throat thickness L2 and the bead stack height H2 after repair are not increased, and the weld bead side It becomes easy to hang down.

  Therefore, by setting the shift amount S2 in the range of 0 ≦ S2 ≦ 3 mm, preferably in the range of 1 ≦ S2 ≦ 2 mm, and performing TIG-MIG repair welding or TIG repair welding, A weld defect such as an excessive cut depth or insufficient throat thickness can be reliably eliminated, and a good repair weld bead (repair weld cross section) can be obtained.

  FIG. 24 is a test result showing an example of the weld cross section of the repair weld bead and the repair presence / absence portion when the TIG-MIG repair weld is performed on the TIG-MIG composite weld main weld bead according to the sixth embodiment of the present invention. FIG.

  The numbers described in the bead appearance photograph in the figure are the test numbers shown in Tables 1 and 2 as in the case of the results shown in FIG. In addition, each welding (repair) cross-sectional portion indicates a position taken from one place of the main weld bead part and two places of the repair bead part.

  The welding speed of the repair weld bead 70 that has been TIG-MIG repair welded from the top of the main weld bead 7 is 354 mm / min, which is the same speed as that of the main welding, and repair is about three times faster than in the case of TIG repair welding. Can do. In TIG-MIG repair welding, for example, repair is performed using repair welding conditions in which the MIG set voltage Em is increased by about 1 V compared to the welding conditions used in the TIG-MIG composite welding of the main welding. The surface shape of the bead can be improved smoothly, and the repair work time can be shortened.

  As described above, in TIG-MIG repair welding, repair welding can be performed at the same speed as the TIG-MIG composite welding of the main welding. For this reason, for example, by applying TIG-MIG repair welding to a weld line in which the length of a defective weld portion to be repaired is relatively long, the time required for repair work can be reduced. Depending on the difference in the length of the defective weld portion to be repaired, TIG-MIG repair welding and TIG repair welding may be used separately.

  In TIG-MIG repair welding or TIG repair welding, the same or the same type of TIG-MIG welding torch 11 used in the main welding process, the same component of SiCu wire (consumable wire 18), Ar gas and He gas, By using the mixed gas (first and second shield gases 14 and 19) for repair welding, it is possible to share the apparatus, reduce equipment investment, reduce manufacturing costs, and the like.

  On the other hand, as can be seen from the photograph of the repair weld cross section shown in FIG. 24, the upper repair weld is deeply melted and fused to both the copper plate side (heat transfer copper fin side) and the lower weld. The weld bead before repair and its weld cross-section 7 do not have poor welds such as undercuts. However, as in the repair test assuming repair repair of the defective part, the weld bead 7 of the simulated defective part By applying TIG-MIG repair welding from above, defective welds such as excessive undercut depth R and insufficient throat thickness L2 can be reliably eliminated, and repair weld beads (repair weld cross section) 70 with good quality can be removed. Can be obtained.

  From these results, for example, even when the undercut depth is around 1 mm, or when the throat thickness L1 and bead height H1 are about 4 mm below the reference values (L1 ≧ T1 = 5 mm, H1 ≧ T1), By applying TIG-MIG repair welding so as to build up in the weld failure part and its vicinity, the undercut can be reliably eliminated, and the throat thickness L2 and bead stacking height H2 satisfying the standard value A good repair weld bead (repair weld cross section) 70 having the above can be formed.

  In addition, by applying the main welding method by TIG-MIG composite welding and the same repair method by TIG-MIG repair welding to the production line of the metal cask welded structure, the metal cask welded structure can be manufactured and continued. it can.

  Further, in the repair bead and repair cross-sectional portion 70 formed by the above-described TIG-MIG repair welding or TIG repair welding, at least undercut depth R is excessive, throat thickness L1 is insufficient, or bead height H1 is insufficient. The bead lamination height H2 of the repair weld including the weld before repair is larger than the throat thickness L2 after repair, and the throat thickness L2 after repair is also the plate thickness T1 of the heat transfer copper fin. Larger (H2> L2> T1) can be formed.

  Further, instead of the TIG-MIG welding torch 11, the first welding process 103 on the inner cylinder 1 side including the temporary assembly process of each fillet joint, the first welding process 103 on the outer cylinder 2 side including the temporary assembly process of each fillet joint. The inner cylinder 1 including the temporary assembly process of each fillet joint using the same MIG welding torch 26 used in the main welding process 110 of No. 2, the same component of the SiCu wire and the mixed gas of Ar gas and He gas. Repair welding conditions substantially the same as the MIG welding conditions used in the first main welding process 103 on the side, the second main welding process 110 on the outer tube 2 side including the temporary assembly process of each fillet joint, or the repair welding conditions It is also possible to perform MIG repair welding in repair welding processes 109, 116, 119 and 122 using repair welding conditions in which the MIG set voltage and heat input are slightly higher than the repair bead and repair beads formed by MIG repair welding. Cross section 70 Has at least an undercut depth R, a throat thickness L1 deficiency or a bead height H1 deficiency, or the like, and a welded weld bead height H2 including a welded portion before repair is eliminated. The throat thickness L2 after repair, and the throat thickness L2 after repair, can be larger than the plate thickness T1 of the heat transfer copper fin (H2> L2> T1).

  Further, as described above, similarly to the case of TIG-MIG repair welding, by performing MIG repair welding so as to build up from the top of the weld bead 7 having a poor weld portion, the throat thickness L1 is insufficient or the bead height H1. It is possible to reliably eliminate defective welds such as shortage and excessive undercut depth R, and to obtain a repair weld bead (repair weld cross section) 70 with good quality.

  In addition, this invention is not limited to the Example mentioned above, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Inner cylinder, 2 ... Outer cylinder, 2-2 ... Outer cylinder board, 3 ... Heat-transfer copper fin, 4 ... Space, 5-1, 5-2 ... 5-N, 8, 8-1 , 8-2 ... 8-N ... fillet joint, 6, 6-1, 6-2 ... 6-N, 9-1, 9-2 ... 9-N ... temporarily welded Welding line of power joint member, 7 ... inner weld, 7b ... bead toe, 7, 7-1, 7-2 ... 7-N, 10-1, 10-2 ... 10-N ... Weld beads (welded cross section), 10 ... outer weld, 11 ... TIG-MIG welding torch, 11A ... welding torch, 12 ... TIG unit, 13 ... non-consumable electrode, 14 ... first shielding gas, 15 ... TIG welding Power source, 16-1, 16-2, 21-1, 21-2, 29-1, 29-2 ... feeder cable, 17 ... MIG unit, 18 ... consumable wire, 19 ... second shield gas, 20, 2 ... MIG welding power source, 20-1 ... Welding control device, 22 ... TIG arc, 23 ... MIG arc, 24 ... Melting pool, 25a ... Welding direction, 25b ... Repair direction, 26 ... MIG welding torch, 27 ... Shield gas for MIG 31 ... Long arm, 31-1 ... Arm drive device, 33 ... Welding robot, 34 ... Wrist, 35 ... Test specimen fixing base, 36 ... Work table, 60 ... Welding line to be repaired, 70, 70-1, 70-2, 100-1, 100-2 ... repair weld bead, 99 ... heat transfer copper fin welding procedure (part 1), 100 ... heat transfer copper fin welding procedure (part 2), 102 ... wire welding cross section A determination process, 103 ... a first welding process on the inner cylinder side, 105 ... a repeated welding process for welding at N locations on the inner cylinder side, 106 ... a repeated welding process for welding and inspection in a small number on the inner cylinder side, 107 117 ... Inner cylinder 109, 116, 119, 122 ... repair welding step, 110 ... second welding step on the outer tube side, 112 ... repeated welding step of welding at N locations on the outer tube side, 113 ... outer tube Repeating welding process of welding and inspection in minor units on the side, 114, 120 ... outer cylinder side inspection process, 123 ... outer cylinder welding finish process, 1071, 1171 ... quality inspection of repair welds, Aw ... wire welding cutting Area, c ... Depth of penetration on steel side, d ... Wire diameter, H1 ... Bead height of weld, H2 ... Bead stack height after repair, Ia ... First welding current, Ib ... Second welding Current, L1 ... Throat thickness of weld, L2 ... Throat thickness after repair, S1 ... Shift amount during welding (first distance), S2 ... Shift amount during repair (second distance), R ... Undercut Depth, T1 ... Heat transfer copper fin thickness, V ... Welding speed, Wf ... Wire feed Speed, Xw ... welding wire length.

Claims (13)

Inclined at substantially equal intervals in the circumferential direction between a steel inner cylinder that houses a collection of spent fuel containing radioactive material and a steel outer cylinder that is coaxially disposed outside the inner cylinder A metal cask that repairs and welds defective welds that occur in the process of the main welding process for welding a plurality of copper heat transfer copper fins to be welded or welded defective parts that are detected in the quality inspection process after welding. A method for repairing a defective weld portion of a welded structure,
When repairing a defective welding part that occurs in the process of the main welding process or a defective welding part determined to be rejected in the quality inspection process after welding, the TIG-MIG welding torch used in the main welding process or The TIG-MIG welding torch or the MIG welding is used in the same direction as the welding direction when the welding torch of the same or the same type as the MIG welding torch, the same component welding wire and the shielding gas are used in the main welding process. Run a torch and repair it by repair welding at least on the welded part so as to build up from above the weld bead part having the welded defective part by composite welding of the preceding TIG and the succeeding MIG or MIG welding. Forming a bead ,
When collecting defective welds in the repair process, repair welding conditions that are substantially the same as the welding conditions used in the main welding process, or other repairs that have increased MIG voltage and heat input over the repair welding conditions. Using the welding conditions, the TIG-MIG welding is performed on a line at a position shifted from the copper bead toe portion of the weld bead portion formed in the main welding process by a predetermined distance to the surface side of the heat transfer copper fin. A torch or MIG welding torch is arranged, and the TIG-MIG welding torch or MIG welding torch is caused to travel so as to pass at least on the line of the defective welding portion, and by combined welding or MIG welding of the preceding TIG and subsequent MIG, wherein as cladding over the weld bead portion having a poor weld portion, that it has to form a repaired bead by applying a repair welding at least in the defective welding portion Poor welding unit repair method for a metal cask welded structure to symptoms. In the method for repairing a defective weld portion of the metal cask welded structure according to claim 1 ,
When the TIG-MIG welding torch is used for TIG-MIG repair welding of the poor welded portion, a TIG arc having a negative electrode polarity on the TIG side is generated in at least the weld bead portion, and power is supplied from the MIG side. A MIG arc having the polarity of the wire to be fed as a positive electrode is generated behind the TIG arc, and one arc is formed by two arcs repelling each other so as to pass at least on the line of the defective weld portion. The TIG-MIG welding torch is caused to travel in the direction of the preceding TIG and the subsequent MIG, and the TIG-MIG repair welding using the TIG arc and the MIG arc is used to build up the weld bead portion having the poor weld portion. Welding of metal cask welded structure characterized in that repair welding is applied to at least the weld defect portion Good part repair method. In the method for repairing a defective weld portion of the metal cask welded structure according to claim 1 ,
When the TIG-MIG welding torch is used for TIG repair welding of the poor welded portion, a TIG arc having a negative electrode polarity on the TIG side is generated in at least the weld bead portion, and a cold without power supply from the MIG side The welding wire as a wire is fed at a low speed slower than the speed of the welding wire used in the TIG-MIG composite welding or the TIG-MIG repair welding in the TIG arc and in the molten pool, and at least on the line of the defective welding portion. The TIG-MIG welding torch travels in the direction of the preceding wire and the subsequent TIG arc so as to pass, and is built up from the top of the weld bead portion having the poor welded portion by TIG repair welding using the preceding wire and the subsequent TIG arc. A metal cast characterized in that repair welding is applied to at least the defective welded portion. Poor welding unit repair method of welded structure. In the method for repairing a defective weld portion of the metal cask weld structure according to claim 3 ,
When TIG repair welding is performed on the defective welded portion, a TIG current equal to or higher than the TIG current used in the main welding process is set, and the welding speed is set in a range of 90 to 150 mm / min to increase the heat input. And using other repair welding conditions set to feed the welding wire without power supply at a lower speed than the speed of the welding wire used in TIG-MIG composite welding or TIG-MIG repair welding. A method for repairing defective welded parts of a metal cask welded structure. In the method for repairing a defective weld portion of a metal cask welded structure according to any one of claims 1 to 4 ,
The metal cask welding structure characterized in that the poor weld portion is generated in the course of the main welding process, or is undercut excessively detected in a quality inspection process after welding, insufficient throat thickness, or insufficient bead height. Repair method for defective welded parts. In the method for repairing a defective weld portion of the metal cask weld structure according to claim 5 ,
The determination of the undercut excess failure is when the depth R of the undercut is greater than 1/10 of the plate thickness T1 of the heat transfer copper fin (R> 0.1 × T1), and the throat thickness The defect judgment of insufficient or bead height is determined when the size of the throat thickness L1 or bead height H1 before repair is smaller than the plate thickness T1 of the heat transfer copper fin (L1 <T1, H1 <T1)). There is provided a method for repairing a defective weld portion of a metal cask welded structure, wherein the repair welding is performed so that the defective weld portion is eliminated. In the method for repairing a defective weld portion of a metal cask welded structure according to any one of claims 1 to 6 ,
The welding wire and shield gas used for repair welding of the defective welding part are CuSi wires containing silicon of the same component as the welding wire used in the main welding process, and a mixture of Ar gas and He gas of the same component. The repair bead is formed by discharging the mixed gas from the tip opening of the welding torch and applying the repair welding so as to build up the CuSi wire from above the weld bead. A method for repairing a defective welded part of a metal cask welded structure. In the method for repairing a defective weld portion of the metal cask welded structure according to claim 1 ,
The predetermined distance S2 for shifting the TIG-MIG welding torch or the MIG welding torch from the copper side bead toe portion to the heat transfer copper fin surface side of the weld bead portion is 0 mm or more and 3 mm or less (0 ≦ S2 ≦ 3). A method for repairing a defective welded part of a metal cask welded structure. In the method for repairing a defective weld portion of the metal cask weld structure according to claim 8 ,
The repair bead and repair cross-section formed by the repair welding have repaired including at least the undercut, the throat thickness is insufficient, or the bead height is insufficient, and the weld including the weld before repair is eliminated. The bead lamination height H2 of the welded portion is larger than the throat thickness L2 after repair, and the throat thickness L2 after the repair is also larger than the plate thickness T1 of the heat transfer copper fin (H2>L2> T1). Repair method for defective welded parts of metal cask welded structures. In the method for repairing a defective weld portion of the metal cask weld structure according to claim 9 ,
The repair process for repair welding the defective weld portion is provided in the next process of the quality inspection process on the inner cylinder side or the quality inspection process on the outer cylinder side or both of the quality inspection processes. The number of (N) end surfaces of the heat transfer copper fins or the other end surface of the heat transfer copper fins are sequentially and repeatedly welded in order, or after the end of the welding process, or the heat transfer divided into a small number of units. One end surface of the copper fin or the other end surface of the heat transfer copper fin is welded and inspected by welding in a small number of units, or is provided in both processes, and in the repair process, A repair method for repairing a defective welded part of a metal cask welded structure, wherein the repair welding is performed so as to eliminate the welded defective part determined to be defective in the quality inspection step. In the method for repairing a defective weld portion of the metal cask welded structure according to claim 1 ,
TIG-MIG welding torch which is the same or the same type as the welding torch scheduled to be used in the repairing process when the welding line of the end face part of the heat transfer copper fin and the joint part is main welded in the main welding process before the repairing process or Using a MIG welding torch, CuSi wire containing silicon of the same component, and a mixed gas of Ar gas and He gas, respectively, a predetermined distance is shifted from the corner portion of the heat transfer copper fin to the surface side of the heat transfer copper fin. The TIG-MIG welding torch or the MIG welding torch is disposed at the welding start position on the weld line at the position, and the TIG-MIG welding is run so as to pass over the welding line from the welding start position to the end position. From the welding start position of the joint part by composite welding of the preceding TIG and the subsequent MIG with a torch or MIG welding with the MIG welding torch Poor welding unit repair method for a metal cask welded structure, characterized in that welding to the welding line to the completion position. In the method for repairing a defective weld portion of the metal cask weld structure according to claim 11 ,
The predetermined distance S1 for shifting the TIG-MIG welding torch or the MIG welding torch from the end face corner portion of the heat transfer copper fin to the surface side of the heat transfer copper fin is 0 mm or more and 4 mm or less (0 ≦ S1 ≦ 4 mm). A method for repairing a defective welded part of a metal cask welded structure. In the method for repairing a defective weld portion of the metal cask weld structure according to claim 11 ,
In the weld bead and weld cross section formed by the welding operation, the throat thickness L1 and bead height H1 are equal to or greater than the plate thickness T1 of the heat transfer copper fin (L1 ≧ T1, H1 ≧ T1). And the undercut depth R is 1/10 or less of the plate thickness T1 (R ≦ (0.1 × T1)). Method.

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