JP2007313541A - Clad tube manufacturing method - Google Patents

Abstract

An object of the present invention is to provide an advantageous manufacturing method of a clad tube, and to improve the soundness at the joint portion of the outer skin material and to improve the corrosion resistance and strength, and to stabilize the clad tube with a uniform thickness of the skin material. To get.
A discontinuous cylindrical shape is formed on the outer peripheral surface of a cylindrical core material 2 by the presence of a butting portion 6 extending in the axial direction obtained by bending a plate material made of a material different from that of the core material 2 into a cylindrical shape. The composite billet 10 is manufactured by applying the frictional stir welding along the abutting portion 6 and covering the obtained cylindrical billet 10 and then extruding the obtained composite billet 10 from a different material. As a layer to be formed, a cylindrical core layer constituted by the extruded layer of the core material 2 and a cylindrical skin layer constituted by the extruded layer of the jacket material 4 are integrally laminated and formed. A clad tube having an outer diameter was formed.
[Selection] Figure 2

Description

  The present invention relates to a method of manufacturing a clad tube, and in particular, a hollow core composed of a cylindrical core material and a cylindrical outer material made of a material different from the core material so as to cover the outer peripheral surface thereof. By extruding the composite billet by mandrel extrusion, the layers made of different materials are crimped and laminated in the radial direction, and can be suitably used for clad pipes, in particular, pipes for heat exchangers for automobiles, etc. The present invention relates to a method of manufacturing a clad tube made of an aluminum alloy.

  Conventionally, this type of clad tube is made of different materials on its outer and inner surfaces, and while ensuring the strength of the tube, it is possible to improve the performance such as durability in its use environment by demonstrating the characteristics of each. Have been developed in a two-layer structure consisting of an outer skin layer and a core material layer, and in a three-layer structure consisting of an outer skin layer, a core material layer, and an inner skin layer. In piping, an aluminum alloy material such as A3004 is used as a core material from the viewpoint of the strength of the piping, while a pure aluminum-based aluminum material such as A1050 having excellent corrosion resistance has been used as a skin material. Yes.

  By the way, in the manufacture of such a clad tube, the simplest method is to adopt a method in which a plurality of elementary tubes with different outer diameters are fitted coaxially with each other to form a composite tube having a structure in which they are overlapped in the radial direction. Although it is conceivable, in such a method, there is inevitably a clearance between the fitted elementary tubes, and it is not expected to form a clad tube having an integral laminated structure. In Patent Documents 1 to 3, a composite billet is produced by concentrically fitting a small-diameter inner billet cylinder into a large-diameter outer billet cylinder, and is extruded by a hot extrusion method. By doing so, it has been clarified that the target clad tube is manufactured.

  However, in the production of a clad tube using such a composite billet, the outer billet cylinder and the inner billet cylinder constituting each of the composite billets are both cast products and used as necessary. After being forged and formed by drilling by machining, in addition to being man-hours and low material yield, the work is complicated and cumbersome and the production cost increases The problem of doing is inherent. Further, instead of such a method for producing a composite billet, each billet cylinder part is formed by sequential centrifugal casting, and a method for forming a target composite billet has also been clarified (Patent Document 3). Even in this method, the work is complicated and troublesome, and it was not practical as a method for producing a composite billet. Further, hot isostatic pressing (HIP) is applied to the composite billet obtained by fitting the outer billet cylinder and the inner billet cylinder, and the metal billet is made between the contact surfaces of the billet cylinders. Although it has also been clarified that the coupling is caused (Patent Document 2), in that case, a large apparatus for HIP is required, and this also increases the manufacturing cost.

  On the other hand, in recent years, the friction stir welding method has been receiving attention as one of the solid-phase welding methods using frictional heat, and not only the joining of butting and overlapping parts of plate-like materials, but also pipes and rods. Adoption of the material having a shape is also being studied. In this friction stir welding method, a rod-shaped probe of a rotary tool is inserted into a butt portion of a material to be joined while rotating, thereby generating frictional heat and causing the material to plastically flow. It is based on the principle of joining materials to be used, and it is a technology that joins materials without melting them. As with arc welding, defects such as blow holes, hot cracks, undercuts, etc. It is recognized that it has the characteristic that no occurs. And, one method for producing a clad material using such a friction stir welding method is disclosed in Patent Document 4, but in this case, a plate-like metal plate material is simply overlapped, It only uses a method in which a rotary tool probe is inserted from one side of the overlapping surface and friction stir welding is used, and a friction stir welding method is used for a hollow tubular clad tube. Thus, there is no clarification about a specific method for manufacturing advantageously.

JP-A-2-258903 JP 2005-506200 Gazette US Pat. No. 5,558,150 JP 2005-205449 A

  Here, the present invention has been made in the background of such circumstances, and the problem to be solved is to provide an advantageous method for manufacturing a clad tube, and to be another problem. However, the present invention is to provide a method capable of stably obtaining a clad tube having a uniform thickness of the skin material, which improves the soundness in the joint portion of the skin material and improves the properties such as corrosion resistance and strength. .

  In the present invention, in order to solve the above-described problems, a method of manufacturing a clad tube having a structure in which layers made of different materials are radially bonded and laminated to be integrated. A cylinder that exhibits a discontinuous cylindrical shape due to the presence of an abutting portion extending in the axial direction, obtained by bending a predetermined plate material made of a material different from the core material into a cylindrical shape on the outer peripheral surface of the cylindrical core material A hollow composite billet is manufactured by friction stir welding the butt portion along the butt portion, and then the different materials are obtained by mandrel extrusion of the obtained composite billet. A cylindrical core layer composed of an extruded layer of the cylindrical core material and a cylindrical skin layer composed of an extruded layer of the cylindrical skin material are integrally formed as a layer made of With an outer diameter of The manufacturing method of the cladding tube, characterized in that allowed to form a head tube, it is to its gist.

  According to one of the desirable embodiments of the method for manufacturing a clad tube according to the present invention, the depth (d) of the friction stir welded portion formed in the butt portion by the friction stir welding operation is such that the cylindrical outer Such a friction stir welding operation is performed so that the thickness (t) of the plate material that provides the skin layer is 1.0 t or more and 1.5 t or less. Thereby, the outer skin material (cylindrical processed material) can be effectively fixed to the core material, and the deviation between them can be advantageously prevented.

  According to another preferred embodiment of the method for manufacturing a clad tube according to the present invention, the composite billet is disposed so as to be in contact with an inner peripheral surface of the cylindrical core member constituting the composite billet. A pipe-shaped endothelium material that provides the innermost layer of the clad tube has a contact surface between the cylindrical core material and the pipe-shaped endothelium material in the circumferential direction at the axial end surface on the extrusion head side of the composite billet. A structure in which friction stir welding is continuously or spot-adopted is adopted, so that the clad tube has a three-layer structure, and the characteristics of the inner surface can be advantageously improved by the selection of the endothelial material. It becomes.

  Furthermore, according to another desirable aspect of the present invention, on the extrusion head side of the composite billet, the cylindrical outer skin material is projected outward in the axial direction from the cylindrical core material to form a stepped portion. On the other hand, a donut plate of the same material as the cylindrical outer skin material is fitted into the stepped portion, and the contact surface between the donut plate and the cylindrical outer skin material is continuously or circumferentially or A configuration in which friction stir welding is performed in a spot manner is employed. In this way, a donut plate made of the same material as the cylindrical processing material that gives the outer skin material is fixed to the head of the composite billet including the core material and the outer skin material. In the clad pipe, the thickness of the outer shell material in the initial stage of the extrusion can be made uniform more quickly. Reduction can be achieved.

  In addition, according to another preferred embodiment of the present invention, the clad tube, wherein the composite billet is disposed so as to be in contact with an inner peripheral surface of the cylindrical core member constituting the composite billet. A pipe-like endothelium material that gives the innermost layer of the pipe-like endothelium material, and the pipe-like endothelium material is projected outward in the axial direction in the same manner as the cylindrical skin material. An accommodating recess having an annular shape is formed between the protruding portions of the cylindrical core member so as to be positioned on the end face on the extrusion head side of the cylindrical core member, while the donut plate is fitted in the accommodating recess. Thus, the contact surfaces between the donut plate and the cylindrical outer skin material and between the donut plate and the pipe-shaped inner skin material are friction stir welded continuously or spotwise in the circumferential direction, respectively. A configuration is employed. Thus, a clad tube having a three-layer structure of an outer skin material layer, a core material layer, and an endothelial material layer can be formed advantageously from the beginning of extrusion.

  Thus, according to the method for manufacturing a clad tube according to the present invention, the cylindrical shell material constituting the composite billet to be subjected to mandrel extrusion uses a predetermined plate material that can be easily manufactured by rolling or the like, and the cylindrical shell material is cylindrical. It can be easily obtained by bending it into a shape, and since it can be made into an integral cylindrical shell material by friction stir welding the butt portion, it can be machined into a conventional cast product By adjusting the inner and outer diameters to the desired size, the manufacturing process becomes extremely simple compared to the case of obtaining the target outer skin material (outer billet cylinder). As a result, it is possible to advantageously reduce the manufacturing cost.

  In the present invention, such a butt portion of the cylindrical outer shell material is joined by friction stir welding, and is advantageously formed as an integral cylindrical body on the outer peripheral surface of the cylindrical core material. However, unlike the case where arc welding such as MIG welding or TIG welding, which is well known as one of the joining means, is employed, there is no occurrence of cracks or distortion in the joint, and blow holes It can be obtained by extruding such a composite billet in addition to the occurrence of defects such as underfill and undercut as well as the occurrence of problems such as poor fusion and poor fusion. In the clad tube, it is possible to effectively suppress or prevent the variation in the thickness of the outer skin layer, and further, the improvement of characteristics such as strength due to the soundness of the joint is achieved advantageously. obtain It is.

  Moreover, the joint formed by friction stir welding of the butt portion of the cylindrical shell material obtained by bending the plate material that provides the cylindrical shell layer of the clad tube is up to about 0.5%. Even if there is a certain amount of clearance between the cylindrical outer shell material and the core material before joining, the cylindrical outer shell material is joined by friction stir welding, so that an integral cylinder is formed. After being formed into a body, the outer shell material (cylindrical body) and the core material are brought into close contact with each other, so that a composite billet with good dimensional accuracy can be obtained.

  Further, according to the present invention, in order to frictionally stir and join the butt portion of the cylindrical outer shell material, the probe of the rotary tool is inserted therein, and the frictional heat is generated by the high-speed rotation, thereby forming the friction stir zone. However, unlike arc welding, the upper and lower materials are rarely stirred, so the core component does not reach the outer skin surface, so the core component is present on the surface of the joint. The problem of deterioration of physical properties such as corrosion resistance caused by doing so is also solved, and it can be made to have excellent physical properties such as corrosion resistance, and since no filler material is required, such a filler material There is no need to worry about the mixing of ingredients.

  Hereinafter, in order to clarify the present invention more specifically, representative embodiments of the present invention will be described in detail with reference to the drawings.

  Here, when manufacturing a clad tube having a structure in which layers made of different materials are pressed and laminated in the radial direction and integrated, first, in the present invention, illustrated in FIGS. Thus, the composite billet 10 is manufactured.

  That is, in these figures, a cylindrical core material 2 is prepared, and a predetermined plate material different from the material of the core material 2 is opposed to the same in a conventional manner using a normal rolling material or the like. A cylindrical outer skin material 4 having a discontinuous cylindrical shape in which the butting portion 6 extends in the axial direction is prepared by bending the both end portions into a cylindrical shape. Here, both the core material 2 and the skin material 4 are made of materials that can be extruded, and combinations of various metal materials can be used depending on the purpose and application of the target cladding tube. In general, a combination of the same metal system, for example, an aluminum system and having different alloy components is preferably employed, and the size and thickness of the core material 2 and the skin material 4 ( Even in the case of (wall thickness), the size and thickness capable of providing the target clad tube are appropriately selected by the extrusion process described later.

  The cylindrical core material 2 and the cylindrical outer shell material 4 shown in FIG. 1 are assembled so that the outer peripheral surface of the core member 2 is covered with the cylindrical outer shell material 4, and in other words, In a state in which the core material 2 is inserted and positioned in the inner hole of the cylindrical outer skin material 4, as shown in FIG. 2A, a known friction stir welding is performed on the butt portion 6 of the cylindrical outer skin material 4. The operation is performed. As is well known, this friction stir welding operation uses a rotary tool 8 that rotates at high speed around an axis, and rotates a rod-shaped probe 8a that is coaxially provided at the tip of the rotary tool 8 while rotating the cylinder 8 By inserting the probe 8a into the butting portion 6 of the cylindrical skin material 4 and contacting the shoulder surface serving as the tip surface of the rotary tool 8 main body, the peripheral portion of the cylindrical skin material 4 is caused to generate frictional heat. The material is plastically flowed to form the friction stir zone 12 to realize the joining of the butt portion 6 of the cylindrical outer skin material 4. In such a friction stir welding operation, although not shown in FIG. 2A, the cylindrical outer skin material 4 is restrained to be fixed in the same manner as in the past by an appropriate restraining jig, The joining operation is allowed to proceed.

  In addition, the friction stir welding operation is performed along the abutting portion 6 of the cylindrical outer skin material 4 so that the abutting portion 6 of the cylindrical outer skin material 4 is joined over substantially the entire length thereof. Thus, the composite billet 10 formed on the outer peripheral surface of the cylindrical core member 2 is obtained as an integral cylindrical shell material (4). That is, such a composite billet 10 has a friction using the rotary tool 8 in the region including the butting portion 6 of the cylindrical outer shell material 4 as shown in FIG. The friction stir zone 12 formed by the stir welding operation becomes a joining portion, and the cylindrical outer skin material 4 exhibiting a discontinuous cylindrical shape is configured as an integral cylindrical body shape, A composite billet 10 having a double cylindrical structure is obtained.

  Moreover, the cylindrical outer shell material 4 joined by such a friction stir welding operation shrinks in the circumferential direction at the joining portion (12), and thus shrinks in the radial direction, so that the friction stir welding operation starts. Even if there is a clearance between the core material 2 and the skin material 4 before, the core material 2 and the skin material 4 come into close contact with each other after such a joining operation. The composite billet 10 in which the integration between the outer shell material 2 and the outer skin material 4 is further enhanced is obtained.

  Further, in the friction stir welding operation, it is desirable that the tip of the probe 8a of the rotary tool 8 is inserted so as to reach the core member 2, and the friction stir welding operation is preferably performed. The depth (d) of the friction stir joint provided in the friction stir zone 12 is 1.0 t or more and 1.5 t or less with respect to the thickness (t) of the plate material constituting the cylindrical outer shell material 4. Thus, by performing the friction stir welding operation, the core material 2 and the skin material 4 are more effectively integrated. It should be noted that the tip of the probe 8a in the rotary tool 8 is inserted too deeply into the core material 2, and the depth (d) of the friction stir welding portion (12) is 1. of the thickness (t) of the plate material. If it exceeds five times, the material of the core material 2 appears on the surface of the friction stir welded portion (12), which may cause problems such as a decrease in the corrosion resistance of the clad tube.

  Thus, the composite billet 10 is obtained by bending, using a plate material made of a mere rolled material, etc., as a cylindrical outer shell material 4 constituting the same, and friction stir welding. By using it, it becomes unnecessary to perform at least troublesome machining since it is manufactured. Therefore, it is easy to manufacture such a cylindrical outer skin material 4, and the material yield is also effectively improved. As a result, manufacturing costs can also be advantageously reduced. In addition, since the core material 2 and the cylindrical outer shell material 4 are advantageously integrated by friction stir welding, the composite billet 10 is subjected to any processing. There is a feature that it can be used as it is for mandrel extrusion operation without being applied.

  Next, the composite billet 10 thus obtained is subjected to mandrel extrusion by a well-known floating mandrel method or a fixed mandrel method to form a clad tube having a target outer diameter. As such, an example of such a mandrel extrusion is shown in FIG. That is, FIG. 3 shows an example of mandrel extrusion by the floating mandrel method, in which the composite billet 10 is placed in the container hole of the container 16 in which the die 14 is arranged, as shown in FIG. The mandrel 18 disposed rearward is inserted into the inner hole 10a of the composite billet 10, and the push plate 20 is brought into contact with the pushing tail portion which is the rear end of the composite billet 10, so that the stem 22 As shown in FIG. 3 (b), the cylindrical core layer 24 and the cylindrical core layer 24 formed by the extruded layer of the cylindrical core member 2 are extruded through the molding opening of the die 14, as shown in FIG. A clad tube 26 having a structure in which a cylindrical outer skin layer 26 constituted by an extruded layer of the outer skin material 4 is integrally adhered and laminated is formed.

  Therefore, the clad tube 28 obtained by the mandrel extrusion has a cylindrical core layer 24 and a cylindrical outer shell constituted by the extruded layer of the cylindrical core member 2 as shown in FIG. It has a structure in which two layers made of different materials composed of a cylindrical outer layer 26 composed of an extruded layer of material 4 are integrally crimped and laminated in the radial direction, and extruded. The joint (12) of the cylindrical outer shell material 4 in the composite billet 10 provided for the above has no portion such as underfill or undercut, and has a large uneven portion such as that caused by arc welding or the like. In the clad tube 28, which is an extruded product obtained, the thickness of the cylindrical outer skin layer 26 is advantageously made uniform, and the thickness of such constituent layers is not present. Uniform It is is able to get a head tube 28 stable.

  Moreover, the component of the core material 2 does not appear to the surface of the joint (12) of the cylindrical outer shell material 4 in the composite billet 10, and is used in arc welding. Since there is no concern about mixing of the components of the filler material, even in the clad tube 28 obtained by mandrel extrusion from such a composite billet 10, the portion corresponding to the joint (12) in the cylindrical skin layer 26 is obtained. The core material component and the filler material component do not appear on the surface. Therefore, the core material component, the mixing of the filler material component, and the deterioration of physical properties caused by the appearance, For example, problems such as a decrease in corrosion resistance can be advantageously avoided.

  By the way, according to the present invention, as a composite billet to be mandrel extruded, it is possible to employ a composite billet 30 having a three-layer structure as shown in FIG. 5 in addition to the composite billet 10 as described above. That is, in this composite billet 30, the abutting portion 6 of the cylindrical outer shell material 4 is friction stir welded to the outer peripheral surface of the cylindrical core material 2 as in the previous example, and the core material 2 and the outer skin material 4 The pipe-shaped endothelium material 32 is inserted and arranged so as to be in contact with the inner peripheral surface of the core material 2, and the contact surface between the core material 2 and the endothelium material 32 is In the axial direction of the composite billet 30, the composite billet 30 is continuously frictionally stirred and joined in the circumferential direction at the extrusion head side of the composite billet 30, that is, the axial end surface portion on the side brought into contact with the die 14 in FIG. 3. A circular joint 34 is formed on the end surface, and thus the core material 2 and the endothelial material 32 are integrally coupled. Here, as the material of the endothelium material 32, a metal material different from the core material 2 is appropriately selected depending on the type of fluid that is circulated in the inner hole. The same material as 4 will be preferably employed.

  In addition, in order to friction stir weld the contact surface between the core material 2 and the endothelial material 32 in the composite billet 30 at the axial end surface on the extrusion head side, the rotary tool 8 similar to the previous example is used, By inserting the probe 8a at the distal end into the contact portion from the end surface in the axial direction and moving the contact surface along the direction in which the contact surface extends in the circumferential direction, the joint portion 34 can be formed continuously in the circumferential direction. It is. However, the joining of the contact surface between the core material 2 and the endothelial material 32 at the axial end face is performed over the entire circumference as illustrated, and in addition to the case where the circular joint 34 is formed, the circumferential direction It is also possible to adopt a spot friction stir welding operation such as intermittently forming joints or providing point joints at a predetermined interval.

  Then, by performing mandrel extrusion using such a composite billet 30, it is composed of an extruded layer of endothelial material 32, which is integrally pressure-bonded and laminated on the inner peripheral surface of the cylindrical core layer 24 shown in FIG. A clad tube in which the innermost layer is formed and three layers of different materials in the radial direction are formed can be stably obtained with a uniform layer thickness.

  Further, in the present invention, it is also possible to advantageously employ a donut plate made of the same material as the cylindrical skin material at the end of the composite billet on the extrusion head side, an example of which is as follows: It is shown in FIG. In this case, the cylindrical outer skin material 4 is protruded axially outward from the cylindrical core material 2 at the end portion on the extrusion head side of the composite billet 40 to be formed. Is formed. The stepped portion 36 is fitted with a donut plate 38 made of the same material as the cylindrical outer shell material 4, and the contact surface between the donut plate 38 and the cylindrical outer shell material 4 is formed on the end face on the extrusion head side. In the position where it is located, the friction stir welding is continuously or spot-frictioned in the circumferential direction by the friction stir welding as in the case of the joining of the above-mentioned endothelial materials. 42 is formed, and the donut plate 38 and the skin material 4 are integrally joined. The height (depth) of the stepped portion 36 is substantially the same as the thickness of the donut plate 38, and is substantially the same as the thickness of the cylindrical outer shell 4 cylinder wall.

  Furthermore, such a donut plate can be disposed even for a composite billet having a three-layer structure as shown in FIG. 5, in which case, for example, as shown in FIG. The donut plate 44 is disposed on the extrusion head side of the composite billet 50 and is integrally bonded to the outer skin material 4 and the inner skin material 32. Specifically, the outer skin material 4 and the inner skin material 32 are respectively projected outward in the axial direction from the end face of the cylindrical core material 2 on the extrusion head side of the composite billet 50. An accommodation recess having an annular shape is formed between the projecting portions of the endothelial material 32 and a donut plate 44 is fitted into the accommodation recess, and the respective contact surfaces, that is, the donut plate 44 and the outer skin material are fitted. 4, and the contact surfaces between the donut plate 44 and the endothelial material 32 are spot-stirred and frictionally agitated at a predetermined interval in the circumferential direction, respectively. , 48 are formed, the outer shell material 4, the donut plate 44, and the inner skin material 32 are integrally joined to form the composite billet 50.

  In the case of the composite billet 40, 50 in which the donut plates 38, 44 are integrally joined, such a donut is produced when mandrel is extruded to produce a target clad tube. Since the plates 38 and 44 constitute the cylindrical outer skin layer (26) in the extruded cladding tube (28), the cladding tube (26) having the desired outer skin layer (26) thickness from the beginning of the extrusion ( 28) can be advantageously obtained, and therefore the cutting portion of the initial extrusion portion of the clad tube (28) can be effectively reduced.

  As the arrangement structure of the donut plates 38 and 44, in addition to the illustrated structure, the axial end surfaces of the core material 2 and the outer skin material 4, and the axial end surface of the endothelial material 32 together with them, It is also possible to adopt a structure in which donut plates are arranged so as to cover those end faces. In that case, the contact surface between the donut plate and the outer skin material appears in the circumferential direction of the composite billet. The friction stir welding operation for joining them is performed in the circumferential direction of the composite billet. Further, in the composite billet having a three-layer structure, it is also possible to adopt a structure in which only the endothelial material is flush with the axial end surface of the core material and a donut plate is fitted in the structure as shown in FIG. .

  Although several embodiments of the present invention have been described in detail above, they are merely examples, and the present invention is not limited by specific descriptions according to such embodiments. It should be understood that this is not to be construed as limiting.

  For example, when manufacturing a composite billet according to the present invention, the friction stir welding operation for joining the butt portion 6 of the cylindrical outer shell material 4 can be performed using various known rotary tools. In addition to the one in which the probe is integrally formed on the main body of the rotary tool as illustrated, even if the main body of the rotary tool and the probe can be moved independently in the axial direction, It can be used in the same manner, and even in the friction stir welding method, any of various known joining methods can be employed.

  Further, in the mandrel extrusion employed in the present invention, the fixed mandrel method can be employed in addition to the exemplified floating mandrel method, and further, the composite billet according to the present invention is extruded by other known mandrel extrusion methods. It is possible to obtain a target clad tube.

  Further, as a method of covering the outer peripheral surface of the cylindrical core material 2 with the cylindrical outer skin material 4, the cylindrical outer skin material 4 is separately prepared, and the core material 2 is placed in the manufactured cylindrical outer skin material 4. In addition to the method of inserting and arranging the core material 2, in the presence of the core material 2, the plate material that gives such an outer skin material 4 is bent into a cylindrical shape, and finally, the cylindrical material around the cylindrical core material 2 is cylindrical. It is also possible that a predetermined friction stir welding operation is performed after the structure in which the outer skin material 4 is disposed.

  In addition, although not enumerated one by one, the present invention can be implemented in a mode to which various changes, modifications, improvements, and the like are added based on the knowledge of those skilled in the art. It goes without saying that any one of them falls within the scope of the present invention without departing from the spirit of the present invention.

  Hereinafter, representative examples of the present invention will be shown to clarify the present invention more specifically, but the present invention is also subject to any restrictions by the description of such examples. It should be understood that it is not.

  First, as a core material (2), a cylindrical aluminum alloy (A3004) cast material cut to an outer diameter of 234 mm and an inner diameter of 80 mm is prepared, and a 10 mm thick aluminum (A1050) rolled plate is bent. Then, a discontinuous cylindrical tube having an outer diameter of 255 m and an inner diameter of 235 mm was prepared as a cylindrical outer covering material (4).

  Then, the prepared core material (2) was covered with the outer skin material (4), and the butted portion (6) was friction stir welded over the entire length along the axial direction. This friction stir welding operation was performed from the extrusion head side toward the tail. Further, the main body (shoulder) of the rotary tool (8) used therein has an outer diameter of 18 mm, the probe has an outer diameter of 5 mm × length of 12 mm, a rotational speed of 2000 rpm, and a joining speed of 500 mm. / Min. As a joining operation. Further, in the entire length of the joining portion (12), the position of 25 mm from the butt portion (6) is restrained and fixed so as to be pressed against the core material (2) from the top of the outer skin material (4) by a restraining jig. And joined.

  Thereafter, an extruded pipe (outer diameter: 79.5 mm, inner diameter: 65.5 mm) made of aluminum alloy (A3004) was fitted so as to be in contact with the inner peripheral surface of the core material (2). 7, the donut plate (44) is fitted into the end on the extrusion head side, and the respective contact surfaces, that is, the contact surface between the outer skin material 4 and the donut plate (44) and the donut plate (44), The contact surface with the endothelial material (32) was line-joined by a friction stir welding operation so that a circular joint continuous in the circumferential direction was formed at the end face portion on the extrusion head side. The rotary tool and joining conditions used there were the same as in the case of the butt portion (6) of the outer skin material (4).

  After heating the composite billet (50) thus obtained to 500 ° C., as shown in FIG. 3, it is accommodated in a container (16) and extruded at a extrusion speed of 5 m / min. A clad tube having a uniform thickness of the outer skin layer and the inner skin layer could be obtained.

It is a perspective explanatory view which clarifies an example of a core material and a skin material which constitute a composite billet used in the present invention. The composite billet used in the present invention is clarified, and (a) shows the step of friction stir welding the butt portion of the outer skin material covered on the core material with a rotary tool, from the axial direction. It is explanatory drawing seen, (b) is a cross-sectional explanatory drawing of the composite billet obtained by joining by such friction stir welding operation. It is explanatory drawing which shows the process of mandrel extrusion of a composite billet according to this invention, (a) is a section explanatory view showing the state where the composite billet was stored in the container of a mandrel extrusion device, (b) It is sectional explanatory drawing which shows the state which is extruding such a composite billet with a mandrel. It is explanatory drawing which shows the cross section of the clad pipe of a two-layer structure obtained by mandrel extrusion in FIG. It is explanatory drawing about another one of the composite billets used in this invention, Comprising: (a) is the front of the axial direction end surface of the assembly body located in the extrusion head side which shows the state before friction stir welding It is explanatory drawing, (b) is explanatory drawing which shows the axial direction end surface by the side of the extrusion head of the composite billet obtained by giving friction stir welding operation to such an assembly. It is explanatory drawing which shows another form of the composite billet used in this invention, Comprising: (a) is a perspective explanatory drawing which shows the form which inserts a donut board in the axial direction edge part of a core material, (b) It is front explanatory drawing which shows the axial direction end surface by the side of the extrusion head of a composite billet obtained by performing friction stir welding operation with respect to the assembly formed by fitting such a donut board. It is explanatory drawing equivalent to FIG.6 (b) which shows the further another example of the composite billet used in this invention.

Explanation of symbols

2 Core material 4 Outer material 6 Butting part 8 Rotating tool 8a Probe 10, 30, 40, 50 Composite billet 10a Inner hole 12, 34, 42, 46, 48 Joint part 14 Die 16 Container 18 Mandrel 20 Press plate 22 Stem 24 Tube Core layer 26 cylindrical outer skin layer 28 clad tube 32 endothelium material 36 stepped portions 38 and 44 donut plate

Claims (5)

In a method of manufacturing a clad tube having a structure in which layers made of different materials are bonded in a radial direction, laminated, and integrated,
A cylindrical shape obtained by bending a predetermined plate material made of a material different from the core material into a cylindrical shape on the outer peripheral surface of the cylindrical core material, and presenting a discontinuous cylindrical shape due to the presence of an abutting portion extending in the axial direction Covering the outer skin material, the abutting portion is friction stir welded along the abutting portion to produce a hollow composite billet, and then extruding the obtained composite billet from the different materials. A cylindrical core layer composed of an extruded layer of the cylindrical core material and a cylindrical skin layer composed of an extruded layer of the cylindrical skin material are integrally formed as a layer to be formed; A method of manufacturing a clad tube comprising forming a clad tube having an outer diameter.   The depth (d) of the friction stir welded portion formed in the butt portion by the friction stir welding operation is 1.0 t or more with respect to the thickness (t) of the plate material that provides the cylindrical skin layer. The method of manufacturing a clad tube according to claim 1, wherein the friction stir welding operation is performed so as to be 5 t or less.   The composite billet has a pipe-shaped endothelium material that is disposed so as to be in contact with an inner peripheral surface of the cylindrical core material that constitutes the composite billet and provides the innermost layer of the clad tube, and the cylindrical core material. 2. The contact surface between the material and the pipe-like endothelium material is friction stir welded continuously or spotwise in the circumferential direction on the axial end surface of the composite billet on the extrusion head side. Or the manufacturing method of the clad tube of Claim 2.   On the extrusion head side of the composite billet, the cylindrical skin material is protruded outward in the axial direction from the cylindrical core material to form a stepped portion. A donut plate made of the same material as the outer skin material is fitted, and a contact surface between the donut plate and the cylindrical outer skin material is continuously or spot-fritted in the circumferential direction by friction stir welding. The manufacturing method of the clad tube as described in any one of Claim 1 thru | or 3. The composite billet has a pipe-shaped endothelium material that is disposed so as to be in contact with an inner peripheral surface of the cylindrical core member that forms the composite billet, and provides the innermost layer of the clad tube, and the pipe-shaped endothelium. The material is made to project outward in the axial direction in the same manner as the cylindrical skin material, and an accommodation recess having an annular shape is formed between the cylindrical skin material and the projecting portion of the pipe-shaped endothelial material. The doughnut plate is fitted into the housing recess, and is formed between the donut plate and the cylindrical outer shell material, and between the donut plate and the donut plate. The method for manufacturing a clad tube according to claim 4, wherein the contact surfaces between the pipe-shaped endothelium materials are friction stir welded continuously or spotwise in the circumferential direction, respectively.

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