JP5050479B2 - ERW pipe manufacturing equipment with good weld characteristics - Google Patents

Description

  The present invention relates to an apparatus for manufacturing a pipe that requires welded portion toughness such as for oil well line pipes or a pipe that requires welded portion strength such as a casing pipe for oil well.

  Usually, pipes are roughly classified into welded pipes and seamless pipes. Welded pipes are manufactured by rounding plates by roll forming etc. and welding by welding the width ends, as in the case of ERW steel pipes. Seamless pipes are made by drilling a lump of material at a high temperature, etc. Rolled to produce. In the case of a welded pipe, it is generally said that the properties of the welded part are inferior to that of the base metal, and in the application of the pipe, guarantees of toughness and strength of the welded part have always been discussed for each application.

  For example, in line pipes that transport crude oil, natural gas, etc., low temperature toughness is important because pipes are often laid in cold regions, and casing pipes that protect mining pipes are used in oil wells for crude oil mining. Needed, tube strength is valued.

  Among welded pipes, ERW pipes are welded without using weld metal, so the construction of the manufacturing apparatus is at least a device for supplying a strip, a device for correcting the shape of the supplied strip, and a correction. It consists of a device for roll-forming the strip, a device for inductively heating the roll-formed strip width end, and a device for pressure-contacting the induction-heated strip width end. Furthermore, in many cases, a device for heat-treating the welded portion of the welded tube and a device for adjusting the outer diameter shape of the tube are provided.

  In addition, the device for roll forming of the strip plate is a breakdown roll stand that bends the strip in a bow shape, a cage roll stand that rounds the strip bent in a bow shape into a tubular shape, and a fin pass molding that shapes the tube after being rolled. It consists of a stand.

  An example of such a conventionally used electric sewing tube manufacturing apparatus is shown in FIG. An uncoiler 1 for supplying the strip 20, a leveler 2 for straightening the strip 20, a roll forming machine 5 for gradually rounding the straightened strip 20, and both left and right width ends of the round strip 20 Induction heating device 6 for inductively heating the part, squeeze roll (electro-sealed welded part) 7 that presses the end of the width of the strip that has been induction heated to form pipe 21, and a bead part that cuts the weld bead part of pipe 21 The cutting machine 8 includes a sizer 9 that adjusts the outer diameter of the pipe 21 after cutting, and a pipe cutting machine 10 that cuts the pipe 21 having the outer diameter adjusted to a predetermined length. The roll forming machine 5 includes a predetermined number (two in this case) of fin pass forming stands 11 at the last stage. The fin shape is a one-step taper shape.

  In general, a hot-rolled sheet serving as a base material of a pipe is subjected to component design, heat treatment, and the like in consideration of the base material characteristics after the manufacture of the pipe, and characteristics such as toughness and strength of the base material are ensured.

  However, since the characteristics of the welded part are greatly influenced by the welding method more than the component design and heat treatment of the base metal, it is particularly important to develop a welding technique in the case of ERW welding.

  As a cause of poor ERW welding, the oxide generated at the width end of the welded strip called penetrator remains without being discharged from the end surface together with the molten steel during ERW welding, and this toughness is caused by this residual penetrator. There were many cases where the strength decreased and the strength was insufficient.

Therefore, in the past, in order to remove the penetrator, which is the main cause of poor ERW welding, from the welded part, techniques for positively discharging molten steel from the width end face of the welded strip have been intensively studied. For example, Patent Literature 1 and Patent Literature 2 describe examples in which the shape of the width end face of the welded strip is studied. In other words, the left and right width end faces of the welded strip are generally rectangular due to slits and end face grinding, but the left and right width end faces are each tapered before roll forming, and the taper machining is performed. It aims at making molten steel discharge | emission favorable at the time of ERW welding by the width end part shape.
JP 2001-17079A JP 2003-164909 A

  However, in the conventional methods described in Patent Documents 1 and 2 described above, only a perforated rolling roll, a cutting tool, and a grinding roll are listed as taper processing means. There are various problems in applying to the manufacturing process of a sewing tube, and further detailed examination is necessary.

  That is, in the actual ERW tube manufacturing process, strips of various thicknesses are used as ERW tubes. For example, when taper shapes are given to the left and right width ends of a strip using a perforated rolling roll However, since different hole rolling rolls must be prepared for each strip thickness and replaced with the hole rolling roll, the production efficiency of the tube is lowered, which is a problem. In addition, when a taper shape is given to the strip width end with a cutting tool or a grinding roll before roll forming, most of the taper is crushed by fin pass rolling on the fin pass forming stand, so that the taper is taken into account It was extremely difficult to apply the shape with a cutting tool or a grinding roll.

  The present invention has been made in view of the circumstances as described above, and imparts an appropriate taper shape to the width end portion of the band plate before the electro-sealing welding so as to maintain the welding quality satisfactorily. It is an object of the present invention to provide an electric-welded pipe manufacturing apparatus with good welded portion characteristics that can suppress a decrease.

  As a result of earnestly examining the method of imparting an appropriate taper shape to the width end portion of the strip without reducing the production efficiency even if the thickness of the strip changes, the present inventors have It came to the mind that it is good to give a taper shape separately with respect to the upper surface side and the lower surface side, respectively.

  That is, if a taper shape is given to the width end portion on one surface side and then a taper shape is given to the width end portion on the other surface side, each taper shape can be changed even if the plate thickness changes variously. Therefore, it is only necessary to finely adjust the vertical position of the apparatus for providing the manufacturing efficiency, so that the production efficiency is not lowered.

  In addition, since the taper applied with a cutting bite or grinding roll before roll forming is mostly crushed by fin pass forming, it is necessary to give a remarkably large taper exceeding 1/2 of the strip thickness. By having a plurality of devices to be applied, it is possible to give a large taper to the width end portion on one surface side of the band plate so that the taper can remain without being crushed by fin pass molding, and the other device can Thus, it is possible to give a taper to the width end portion on the surface side.

  And since the strip is substantially flat on the roll forming entry side, it is preferable to give a taper shape to the width end of one surface side by cutting or grinding. These taper-shaped imparting devices by cutting and grinding require a large installation space due to the relatively large scale of the device, and are installed because the distance between the ends is reduced by rolling the strip during or after roll forming. hard. Moreover, since it is difficult for the apparatus which performs cutting and grinding to restrain a strip | plate up and down with an apparatus alone, the precision of an installation position is requested | required with the apparatus which hold | maintains the position which a strip | pass passes. Therefore, it is necessary to increase the rigidity of the gantry of the apparatus, and a larger installation space is required. Therefore, the cutting or grinding apparatus is preferably installed before roll forming.

  At this time, in order to efficiently taper the left and right end portions of the sheet width, the cutting or grinding apparatus is made of a cutting or grinding roll, and the cutting or grinding roll is inclined with respect to the vertical end surface in the thickness direction. It is preferable to use the device to be used.

  Moreover, in order to give a taper shape to the width | variety edge part of the other surface side, it is good to utilize the fin pass shaping | molding stand in the middle of roll shaping | molding. In the fin pass forming stand, the strip plate is filled with the fin pass roll, so that the plate width end is strongly pressed. Therefore, in the fin path forming stand, the fin shape may be a two-step taper, and the fin shape may be transferred to the strip using the strong pressure at the plate width end.

  The present invention is based on the above concept and has the following features.

  [1] At least a device for supplying a strip, a device for correcting the shape of the supplied strip, a device for roll-forming the corrected strip, and guiding the roll-formed strip width end In an electric sewing tube manufacturing apparatus comprising a heating apparatus and an apparatus for press-contacting an induction-heated strip width end, the width end of the strip is cut after the device for correcting the shape of the strip. The apparatus for performing roll forming has a fin path forming apparatus incorporating fins having at least two stages of taper shapes, and the apparatus for cutting the width end portion of the band plate The taper shape is given to one surface side of the width end portion of the band plate, and the taper shape is given to the other surface side of the width end portion of the band plate by the fin path forming device. Electric sewing with good weld characteristics Of manufacturing equipment.

  [2] The electric sewing tube having good welded portion characteristics according to [1], wherein the device for cutting the width end portion of the strip is a cutting device in which cutting blades are arranged in a roll shape. Manufacturing equipment.

  [3] At least a device for supplying the strip, a device for correcting the shape of the supplied strip, a device for roll-forming the corrected strip, and guiding the roll-formed strip width end In an electric resistance welded tube manufacturing apparatus comprising a heating device and a device for pressure-welding an induction-heated strip width end, the width end of the strip is ground after the device for correcting the shape of the strip. The apparatus for performing roll forming has a fin path forming apparatus in which fins having at least two stages of taper shapes are incorporated, and apparatus for grinding the width end portion of the strip The taper shape is given to one surface side of the width end portion of the band plate, and the taper shape is given to the other surface side of the width end portion of the band plate by the fin path forming device. Electric sewing with good weld characteristics Of manufacturing equipment.

  [4] Production of an electric resistance welded tube with good welded portion characteristics according to [3], wherein the device for grinding the width end portion of the strip is a grindstone polishing device comprising a roll-shaped grindstone. apparatus.

  [5] The taper shape applied to each surface side of the width end portion of the band plate is the length in the plate thickness direction from the taper start position to the end position, with the angle from the plate thickness direction vertical end surface being 25 ° to 50 °. The thickness of the sheet thickness is 20% to 40%, and the welded tube manufacturing apparatus with good welded portion characteristics according to any one of the above [1] to [4].

  In the present invention, an electric resistance welded tube having remarkably good toughness and welding strength can be produced with high efficiency.

  One embodiment of the present invention is described below.

  An electric resistance welded tube manufacturing apparatus according to an embodiment of the present invention is shown in FIG. The electric sewing tube manufacturing apparatus includes an uncoiler 1 that supplies a belt plate 20, a leveler 2 that straightens the belt plate 20, a roll forming machine 5 that gradually rounds the straightened belt plate 20, and a round machine. An induction heating device 6 that induction-heats the left and right width end portions of the strip 20, a squeeze roll (electrically welded portion) 7 that presses the induction-heated strip width end to form a tube 21, It comprises a bead part cutting machine 8 for cutting the weld bead part, a sizer 9 for adjusting the outer diameter of the pipe 21 after cutting, and a pipe cutting machine 10 for cutting the pipe 21 having the outer diameter adjusted to a predetermined length. Has a basic configuration. The roll forming machine 5 includes a predetermined number (two in this case) of fin pass forming stands 4 at the last stage.

  And in addition to said basic structure, the electric resistance welded tube manufacturing apparatus which concerns on this embodiment provides a taper shape between the leveler 2 and the roll forming machine 5 at the left and right width end portions on the upper surface side of the band plate 20. Cutting or grinding means 3 is provided. The cutting or grinding means 3 is shown in FIG. 2 as viewed in the direction of arrows A-A in FIG. 1, and as shown in FIG. a)) or a roll-shaped grinding wheel 3b (FIG. 3B) is rotated by a motor 3c, and its cutting surface or grinding surface is parallel to the roll axis. A pair of left and right are arranged in the width direction of the band plate 20, and each roll axis is inclined at a predetermined angle α from the vertical direction, whereby a predetermined taper shape (width) is formed at both left and right width end portions on the upper surface side of the band plate 20. An inclination angle α from the end surface toward the upper surface and a plate thickness direction distance β) from the upper surface of the starting position at the width end surface are provided. Hereinafter, the cutting tool 3a in which the cutting blades are arranged in a roll shape will be referred to as a cutting roll 3a, and the roll-shaped grinding wheel 3b will be referred to as a grinding roll 3b.

  Furthermore, the electric resistance welded tube manufacturing apparatus according to this embodiment is shown in FIG. 4 (a) as viewed in the direction of arrows BB in FIG. 1, and as shown in FIG. 4 (b). 4 has a fin shape having a two-step taper (a second-step taper inclination angle α, a second-step inclined portion vertical length β), and the shape is formed at the width end of the band plate 20. By transferring to the portion, a predetermined taper shape (inclination angle α from the width end surface toward the lower surface, the width end surface at the left and right width end portions on the lower surface side of the strip 20 (outer surface side of the tube 21) A plate thickness direction distance β) from the lower surface of the starting position is given.

  In the ERW pipe manufacturing apparatus configured as described above, when the strips 20 having different thicknesses are continuously passed, the left and right width end portions on the upper surface side and the lower surface side for each strip plate 20. When a predetermined taper shape is applied to the belt plate 20, the cutting roll 3a or the grinding roll 3b is inclined by a predetermined angle α, the height direction position is finely adjusted, and the left and right width ends on the upper surface side of the band plate 20 are adjusted. By cutting or grinding the portion, a predetermined taper shape is given to the left and right width end portions on the upper surface side of the band plate 20, and both the left and right sides on the lower surface side of the band plate 20 in the final stand 4a of the fin pass molding. By transferring the fin shape to the width end portion, a predetermined taper shape is given to the left and right width end portions on the lower surface side of the band plate 20. Thus, unlike the prior art, it is not necessary to replace the perforated rolling roll for each thickness of the strip, so both the left and right widths of the strip 20 according to the thickness without reducing the production efficiency. A predetermined taper shape can be given to the end portion.

  As described above, in the electric resistance welded tube manufacturing apparatus according to this embodiment, it is suitable for the left and right width end portions of the band plate 20 before the electric resistance welding, corresponding to the change in the thickness of the band plate 20 flexibly. Since a tapered shape can be imparted, it is possible to maintain a good welding quality and to suppress a decrease in manufacturing efficiency, so that it is possible to manufacture an ERW pipe with good welded part characteristics with high efficiency. is there.

  In addition, about the taper shape given to both the left and right width end portions of the strip 20, the angle from the vertical end surface in the plate thickness direction (the length in the plate thickness direction from the taper start position to the end position is above the width end surface of the strip 20 (Inclination angle toward the surface or the lower surface) α is 25 ° to 50 °, and the length in the thickness direction from the taper start position to the end position (the taper start position at the width end face of the band plate 20 and the upper or lower surface) The distance from the surface (β) is preferably 20% to 40% of the strip thickness.

  That is, when the inclination angle α is less than 25 °, the molten steel is not sufficiently discharged from the central portion of the strip plate thickness, the penetrator remains and becomes defective, and the toughness and strength after ERW welding are reduced. If the angle α exceeds 50 degrees, the taper shape remains as a wrinkle of the pipe of the product even after the electric resistance welding, which is a problem. Further, when the distance β is less than 20% with respect to the plate thickness, the molten steel discharge at the center portion of the plate thickness becomes insufficient and the penetrator tends to remain, and when the distance β exceeds 40% with respect to the plate thickness. Even after ERW welding, the taper shape remains as a flaw in the tube of the product, which is a problem.

  Hereinafter, a description will be given based on examples.

  Here, a φ600 electric sewing tube is manufactured using a strip (steel strip) having a plate width of 1920 mm × 19.1 tmm, and then a strip (steel strip) having a plate width of 1920 mm × 11.3 tmm is used. , Φ600 electric resistance welded tube was manufactured.

  And the test piece was cut out from the weld part of the manufactured ERW pipe, the Charpy test was done, and the performance was evaluated. Each Charpy test piece is taken from 10 points with different pipe longitudinal directions, the specimen length direction is parallel to the pipe circumferential direction, the notch length center is taken as the weld thickness center position, and 2 mmV of JIS5 An impact test at −46 ° C. was performed as a notch impact test piece, and the absorbed energy and the brittle fracture surface ratio were measured. In addition, the absorbed energy was 125 J or more and the brittle fracture surface ratio was 35% or less as the allowable performance range.

  (Example of the present invention) As an example of the present invention, the above-described electric resistance welded tube was manufactured using the electric resistance welded tube manufacturing apparatus according to the embodiment of the present invention shown in FIG. At that time, the cutting roll 3a shown in FIG. 3A was used as the cutting or grinding means 3 for imparting a taper shape to the left and right width end portions on the upper surface side of the strip. Further, the inclination angles α of the tapered shapes on the upper surface side and the lower surface side were both 30 °.

  (Conventional example) As a conventional example, the above-mentioned electric resistance welded tube was manufactured using the electric resistance welded tube manufacturing apparatus shown in FIG.

  Table 1 shows the results of measuring the Charpy impact value and the brittle fracture surface ratio at the welded portion of the electric resistance welded tube manufactured as described above.

  From Table 1, the ERW pipe according to the example of the present invention has high impact strength at the welded portion, low brittle fracture surface ratio, good toughness, and high product reliability. On the other hand, the ERW pipe according to the conventional example has a low impact strength at the welded portion, a high brittle fracture surface ratio, a low toughness, and poor product reliability.

It is explanatory drawing of the electric sewing tube manufacturing apparatus which concerns on one Embodiment of this invention. It is an AA arrow line view of FIG. FIG. 3 is a partial detail view of FIG. 2. It is a BB arrow line view of FIG. It is explanatory drawing of the conventional electric sewing tube manufacturing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Uncoiler 2 Leveler 3 Cutting or grinding means 3a Cutting roll 3b Grinding roll 3c Motor 4 Fin pass forming stand 4a Final stand of fin pass forming 5 Roll forming machine 6 Induction heating device 7 Squeeze roll (electro-sewn welding part)
8 Bead cutting tool 9 Sizer 10 Pipe cutting machine 11 Fin pass forming stand 20 Strip plate 21 Pipe

Claims (5)

  At least a device for supplying a strip, a device for correcting the shape of the supplied strip, a device for roll-forming the corrected strip, and a device for induction heating the roll-formed strip width end And a device for cutting the width end of the strip after the device for correcting the shape of the strip The roll forming apparatus includes a fin path forming apparatus in which fins having at least two or more stages of taper shapes are incorporated, and a band cutting device is used to cut the width end of the band plate. A taper shape is given to one surface side of the width end portion of the plate, and a taper shape is given to the other surface side of the width end portion of the band plate by the fin path forming device. ERW pipe with good weld properties Apparatus.   The apparatus for manufacturing an electric resistance welded tube according to claim 1, wherein the device for cutting the width end portion of the strip is a cutting device in which cutting blades are arranged in a roll shape.   At least a device for supplying a strip, a device for correcting the shape of the supplied strip, a device for roll-forming the corrected strip, and a device for induction heating the roll-formed strip width end And a device for pressing the width end of the strip that has been induction-heated, and a device for grinding the width end of the strip after the device for correcting the shape of the strip The roll forming apparatus includes a fin path forming apparatus in which fins having at least two stages of taper shapes are incorporated, and the apparatus for grinding the width end portion of the band plate A taper shape is given to one surface side of the width end portion of the plate, and a taper shape is given to the other surface side of the width end portion of the band plate by the fin path forming device. ERW pipe with good weld properties Apparatus.   The apparatus for manufacturing an electric resistance welded tube with good welded portion characteristics according to claim 3, wherein the device for grinding the width end portion of the strip is a grindstone polishing device made of a roll-shaped grindstone.   The taper shape to be applied to each surface side of the width end portion of the band plate is the plate thickness direction length from the taper start position to the end position, with the angle from the vertical end face in the plate thickness direction being 25 ° to 50 °. 5. The apparatus for manufacturing an electric resistance welded tube with good welded portion characteristics according to claim 1, wherein the thickness is set to 20% to 40% of the thickness.

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