Method and device for correcting butt welded joints

Abstract

To provide a butt weld joint correction method which can sufficiently correct welding deformation for a butt weld joint with a stainless steel plate as a base material.SOLUTION: In a correction method for a weld joint 100 including a pair of base materials 101 comprising stainless steel plate and a weld zone 102, a rolling roll 2 is brought into contact with each of the pair of base materials 101 from both sides of the base material 101 in a plate thickness direction in a region separated from a boundary 103 between the weld zone 102 on a base material surface and the base material 101 by 10 mm or more and within 25 mm from the boundary 103, and the base material 101 is rolled along a longer direction of the weld zone 102.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for straightening a butt welded joint in which a stainless steel plate is used as a base material, and to an apparatus for straightening a butt welded joint. [Background technology]

[0002] When butt welding is performed on a base material made of stainless steel plate, the base material may undergo welding deformation at the welded joint after welding, mainly due to thermal contraction in the direction of the weld line.

[0003] Welding deformation of the base material, when viewed from the welding torch side, can be so-called angular deformation, which is a V-shape with the weld line as the valley line, buckling deformation, in which the base material curves along the weld line so that it protrudes toward the welding torch side, or a combination of these. This type of welding deformation can be reduced to some extent by restraining the base material during welding, but there is a limit to how much deformation can be reduced.

[0004] In order to correct welding distortion, a correction process may be performed on the welded joint after welding. Conventional correction methods include local heating and hammering. However, the local heating method is difficult to apply to stainless steel due to concerns about high-temperature oxidation and sensitization. In addition, the hammering method requires the experience and skill of the worker, and has the problem of being unable to adequately handle complex distortions.

[0005] There is also a method of straightening the deformed welded joint by pressing it with a roll. Patent Document 1 describes a method of removing welding deformation in which only the high residual stress area near the weld bead is sufficiently cooled by small rollers, and in a state where residual stress is generated, a sufficiently large pressure is applied in the plate base material in the plate thickness direction. Patent Document 2 describes a method of using roll pressurization to press a plate part in a range of 30 mm from the weld boundary parallel to the weld in a butt welded joint of aluminum and its alloy plates.

[0006] However, in the case of stainless steel plates, significant angular distortion or buckling distortion may occur due to low thermal conductivity, and sufficient correction is difficult using the methods described in Patent Document 1 or Patent Document 2. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 52-41144 [Patent Document 2] Japanese Patent Application Publication No. 8-39285 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a method and device for correcting a butt welded joint that are capable of sufficiently correcting welding distortion in a butt welded joint whose base material is a stainless steel plate. [Means for solving the problem]

[0009] [1] A method for correcting a butt welded joint having a pair of base materials and a welded portion made of stainless steel plates, comprising: For each of the pair of base metals, a rolling roll is brought into contact with both sides of the base metal in the plate thickness direction within a region on the surface of the base metal that is 10 mm or more away from the boundary between the welded portion and the base metal and within 25 mm of the boundary, and the base metal is rolled along the longitudinal direction of the welded portion. death, As the rolling roll, a crown roll having a roll surface bulging in an arc shape is used. How to correct a butt welded joint 。 [ 2 ] A method for correcting a butt welded joint having a pair of base materials made of stainless steel plates and a welded portion, comprising the steps of: For each of the pair of base metals, a rolling roll is brought into contact with both sides of the base metal in a thickness direction within a region on the surface of the base metal that is 10 mm or more away from a boundary between the welded portion and the base metal and within 25 mm of the boundary, and the base metal is rolled along the longitudinal direction of the welded portion; The welded portion is pressed by a straightening roll or a straightening jig from the side where the welded portion protrudes due to angular distortion against the butt welded joint being rolled by the rolling roll, During the rolling, the distance between the boundary side end face of the rolling roll and the boundary is set to a dimension equal to or larger than the plate thickness of the base material. 、 How to straighten a butt welded joint. [3] The method for correcting a butt welded joint according to [1] or [2], wherein the reduction ratio in rolling the base metal with the reduction rolls is 0.5 to 2.0%. [4] A method for correcting a butt welded joint having a pair of base materials and a welded portion made of stainless steel plates, comprising: a first step of rolling the base metal along the longitudinal direction of the weld by contacting a rolling roll with both sides of the base metal in a thickness direction of the base metal in a region of the base metal surface that is 10 mm or more away from a boundary between the weld and the base metal and within 25 mm of the boundary; A second step of rolling the base material along the longitudinal direction of the welded portion by the rolling rolls while contacting the region with rolling rolls from both sides in the plate thickness direction of the base material and pressing the welded portion with a straightening roll or a straightening tool from the side where the welded portion protrudes due to angular deformation; Equipped with A method for correcting a butt welded joint, wherein during the rolling in the first and second steps, a distance between the end face of the rolling roll on the boundary side and the boundary is set to be equal to or greater than a dimension corresponding to a plate thickness of the base material. [5] In the rolling of the base material by the rolling rolls in the first step, the rolling reduction is 0.5 to 2.0%, The method for correcting a butt welded joint according to [4], wherein in the second step, the base metal is rolled by the reduction rolls at a reduction rate of 0.1 to 2.0%. [6] As the rolling roll, a crown roll having a roll surface bulging in an arc shape is used, 2

[0023] A method for correcting a butt welded joint described in any one of [1] to [5]. [7] A device for correcting a butt welded joint comprising a pair of base materials and a welded portion made of stainless steel plates, For each of the pair of base metals, a rolling roll is provided that contacts the base metal from both sides in the plate thickness direction within an area 10 mm or more away from the boundary between the welded portion and the base metal on the surface of the base metal and within 25 mm from the boundary, and rolls the welded portion along the longitudinal direction.、 The rolling roll is a crown roll whose roll surface is bulged in an arc shape. A device for straightening a butt welded joint. [8] A device for correcting a butt welded joint having a pair of base materials and a welded portion made of stainless steel plates, comprising: For each of the pair of base metals, a rolling roll is provided that contacts the base metal from both sides in the plate thickness direction within a region on the base metal surface that is 10 mm or more away from the boundary between the welded portion and the base metal and within 25 mm from the boundary, and rolls the welded portion along the longitudinal direction, A straightening roll or a straightening tool is provided to press the welded portion from the side where the welded portion protrudes due to angular distortion against the welded joint being rolled by the rolling roll. 、 A device for straightening butt welded joints. [9] The rolling roll is a crown roll whose roll surface is bulged in an arc shape. [8] An apparatus for straightening a butt welded joint as described above. Effect of the Invention

[0010] According to the findings of the present inventor, when buckling deformation occurs, in each of the pair of base metals of a butt welded joint, the difference between the longitudinal residual stress of the weld on the surface side of the base metal and the longitudinal residual stress of the weld on the back side opposite to the surface becomes large in an area 10 to 25 mm away from the boundary between the weld and the base metal on the surface of the base metal. Therefore, in the present invention, rolling is performed on both sides of the thickness direction of the base metal by rolling rolls. This makes it possible to correct the buckling deformation in the butt welded joint. In addition, the correction method of the present invention can perform sufficient correction compared to the conventional correction method using roll pressure. Furthermore, since the present invention does not require heating of the base metal, it can be suitably applied to butt welded joints made of stainless steel plates. Furthermore, since the present invention does not involve hammering on the base metal, no skill is required from the worker and it can also handle welding deformations of complex shapes.

[0011] According to the present invention, the angular distortion can be corrected together with the buckling distortion by pressing the welded portion with a straightening roll or a straightening tool from the side where the welded portion protrudes due to the angular distortion of the welded joint being rolled by the rolling rolls. Also, by leaving a distance between the boundary end face of the rolling roll on the boundary side and the boundary that is equal to or greater than the thickness of the base metal, it is possible to prevent the base metal of the welded joint pressed by the straightening roll or the straightening tool from coming into contact with the end face of the rolling roll on the opposite side of the straightening roll or the straightening tool across the welded joint.

[0012] Next, according to the correction method of the present invention, for example, for a butt welded joint in which both buckling deformation and angular distortion have occurred and the amount of buckling deformation has become large, the buckling deformation is corrected by performing a first step of rolling the above-mentioned area of ​​the base material with a reduction roll, and then performing a second step of rolling the above-mentioned area of ​​the base material with a reduction roll and pressing the welded portion with a roll or a jig, thereby correcting the buckling deformation and angular distortion, and making it possible to correct welding distortion more reliably.

[0013] Furthermore, according to the straightening device of the present invention, a welded joint that has been deformed due to welding can be easily straightened. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view showing an example of a butt-welded joint to be subjected to the method for correcting a butt-welded joint of the present invention. [Diagram 2] FIG. 2 is a diagram for explaining the method for correcting a butt welded joint according to the first embodiment of the present invention, and is a front view seen from the conveyance direction of the welded joint. [Diagram 3] FIG. 3 is a perspective view showing a butt welded joint straightened by the straightening method of the first embodiment of the present invention. [Figure 4] FIG. 4 is a distribution diagram showing the distribution of residual stress on the surface side of a butt welded joint before correction. [Diagram 5] FIG. 5 is a distribution diagram showing the distribution of residual stress on the back side of a butt welded joint before correction. [Figure 6]FIG. 6 is a perspective view showing another example of a butt-welded joint to be subjected to the method for correcting a butt-welded joint of the present invention. [Figure 7] FIG. 7 is a diagram for explaining a method for correcting a butt welded joint according to a second embodiment of the present invention, and is a front view seen from the conveyance direction of the welded joint. [Figure 8] FIG. 8 is a diagram for explaining a method for correcting a butt welded joint according to a second embodiment of the present invention, and is a side view seen from the side in the conveyance direction of the welded joint. [Figure 9] FIG. 9 is a perspective view showing a butt welded joint straightened by the straightening method according to the second embodiment of the present invention. [Figure 10] FIG. 10 is a diagram for explaining a method for correcting a butt welded joint according to a third embodiment of the present invention, and is a front view seen from the traveling direction of reduction rolls. [Figure 11] FIG. 11 is a diagram for explaining an example of a method for correcting a butt welded joint according to the third embodiment of the present invention, and is a side view seen from the side in the traveling direction of the rolling rolls. [Figure 12] FIG. 12 is a diagram for explaining another example of the method for correcting a butt welded joint according to the third embodiment of the present invention, and is a side view seen from the side in the traveling direction of the reduction rolls. [Figure 13] FIG. 13 is a perspective view showing another example of a butt-welded joint to be subjected to the method for correcting a butt-welded joint of the present invention. [Figure 14] FIG. 14 is a diagram for explaining a first step of a method for correcting a butt welded joint according to a fourth embodiment of the present invention, and is a front view seen from the traveling direction of reduction rolls. [Figure 15] FIG. 15 is a perspective view showing a butt welded joint after the first step. [Figure 16] FIG. 16 is a front view seen from the conveyance direction of the welded joint, illustrating a second step of the method for correcting a butt welded joint according to the fourth embodiment of the present invention. [Figure 17] FIG. 17 is a side view showing the butt welded joint after the second step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the method for correcting a butt welded joint of the present invention will be described with reference to the drawings. In the following description, a "butt welded joint" may be referred to as a "welded joint", and a "method for correcting a butt welded joint" may be referred to as a "correction method".

[0016] (First embodiment) First, a welded joint to be subjected to the straightening method of the present embodiment will be described. FIG. 1 is a perspective view showing an example of a welded joint to be subjected to the straightening method of the present embodiment. The welded joint 100 shown in FIG. 1 includes a pair of base materials 101 made of stainless steel plates and a welded portion 102. The type of stainless steel plate constituting the base material 101 is not particularly limited, and may be any of an austenitic stainless steel plate, a ferritic stainless steel plate, a martensitic stainless steel plate, and a ferritic-austenitic duplex stainless steel plate, but is particularly suitable for use with a welded joint made of an austenitic stainless steel plate. Austenitic stainless steel plates have a relatively low thermal conductivity and tend to be easily subject to welding deformation, and are therefore particularly suitable as a target for the straightening method of the present invention. In addition, the base material 101 is preferably a thin steel plate having a plate thickness of 4 mm or less that can be welded in a single layer.

[0017] The welded portion 102 is a butt welded portion formed by butting the ends of each base material 101 together and welding them. In FIG. 1, the upper surface of the base material 101 is called the front surface 101a, and the lower surface of the base material 101 is called the back surface 101b. The welded joint 100 shown in FIG. 1 is formed by butting two base materials 101, 101 together and welding them while applying heat input from the front surface 101a side with a welding torch. In the welded joint 100 shown in FIG. 1, buckling deformation occurs after butt welding. The buckling deformation in the welded joint 100 shown in FIG. 1 is a welding deformation in which the base material 101 is curved so as to protrude toward the welding torch along the longitudinal direction of the welded portion 102.

[0018] Next, the straightening method of this embodiment will be described. FIG. 2 is a diagram for explaining the straightening device and the straightening method of this embodiment, and is a front view seen from the conveying direction of the welded joint. In the straightening method of this embodiment, as shown in FIG. 2, a straightening device 1 is used that includes a rolling roll 2 that contacts the base metal 101 from both sides in the plate thickness direction and rolls the base metal 101 along the longitudinal direction of the welded portion 102. The rolling roll 2 is configured so as to be able to roll an area on the surface 101a of the base metal 101 that is 10 mm or more away from the boundary 103 between the welded portion 102 and the base metal 101 and within 25 mm from the boundary 103 along a direction parallel to the longitudinal direction of the welded portion 102. The reduction rate during rolling can be adjusted within a range of at least 0.5 to 2.0%.

[0019] In the straightening method of this embodiment, the work rolls 2 are brought into contact with the base metal 101 from both sides in the thickness direction of the base metal 101, and the base metal 101 is rolled along the longitudinal direction of the welded portion 102, thereby straightening the welding deformation. Rolling is performed simultaneously on each of a pair of base metals 101 on both sides in the width direction of the welded portion 102. Here, the area in which the work rolls 2 are brought into contact is within a region R that is 10 mm or more away from a boundary 103 between the welded portion 102 and the base metal 101 on the surface 101a of the base metal 101, and is within 25 mm of the boundary 103. The rolling conditions in the straightening method will be described below.

[0020] The base materials 101 to be rolled are a pair of base materials 101 on both sides in the width direction of the welded portion 102. If rolling is performed only on the base materials 101 on one side of the welded portion 102 in the width direction, only one of the base materials 101 will stretch along the longitudinal direction of the welded portion 102, making it impossible to correct the welding deformation and causing the welded portion 102, which has been formed in a straight line, to curve. Therefore, it is preferable to simultaneously roll the base materials 101 on both sides of the welded portion 102 in the width direction.

[0021] As shown in Fig. 2, it is preferable to use a crown roll in which the roll surface 2b bulges in an arc shape as the rolling roll 2. By using a crown roll as the rolling roll 2, the contact area with the base material 101 is reduced, making it possible to roll down efficiently, and the indentations caused by the rolling roll 2 are less noticeable. Furthermore, even if the base material 101 is tilted relative to the rolling roll 2 during rolling, there is no risk of plastic deformation of the base material 101. It is preferable that the crown height of the rolling roll 2 is 100 µm or more.

[0022] 2, the area where the rolling roll 2 comes into contact is within a region that is 10 mm or more away from a boundary 103 between the welded portion 102 and the base metal 101 on the surface 101a of the base metal 101 and within 25 mm of the boundary 103. The boundary 103 between the welded portion 102 and the base metal 101 is preferably the boundary between the weld metal of the welded portion 102 and the base metal.

[0023] When buckling deformation occurs in the welded joint 100, in a region R that is 10 mm or more away from the boundary 103 and within 25 mm from the boundary 103, the difference between the longitudinal residual stress of the welded portion 102 on the front surface 101a side of the base material 101 and the longitudinal residual stress of the welded portion 102 on the back surface 101b side opposite the front surface 101a becomes large in each of the pair of base materials 101 of the welded joint 100. It is presumed that the buckling deformation occurs due to this difference in residual stress. Therefore, in this embodiment, the base material 101 is sandwiched between the rolling rolls 2 from both sides in the thickness direction of the region R and lightly pressed down, thereby reducing the difference in residual stress between the front surface 101a and the back surface 101b of the base material 101. This reduces the buckling deformation. The range in which the rolling rolls 2 are in contact is more preferably within a region that is 12 mm or more away from the boundary 103 and within 17 mm from the boundary 103.

[0024] The reduction ratio when performing soft reduction is in the range of 0.5 to 2.0%. By setting the reduction ratio to 0.5% or more, the difference in residual stress between the front surface 101a and the back surface 101b of the base material 101 can be sufficiently reduced, and buckling deformation can be mitigated. In addition, by setting the reduction ratio to 2.0% or less, the occurrence of cracks in the vicinity of the welded portion 102 can be prevented.

[0025] Fig. 3 shows a welded joint 110 after the correction. In the welded joint 100 shown in Fig. 3, the curvature of the base material 101 along the longitudinal direction of the welded portion 102 is eliminated, and the buckling deformation is corrected.

[0026] 4 shows a distribution diagram of residual stress on the front surface 101a side of the butt welded joint 100 before correction, and FIG. 5 shows a distribution diagram of residual stress on the back surface 101b side. As shown in FIG. 4, on the front surface 101a side of the welded joint 100, tensile residual stress occurs in the vicinity of the welded portion 102 along the longitudinal direction of the welded portion 102. On the other hand, as shown in FIG. 5, on the back surface 101b side of the welded joint 100, compressive residual stress occurs in the vicinity of the welded portion 102 along the longitudinal direction of the welded portion 102. In the region R that is 10 mm or more away from the boundary 103 between the welded portion 102 and the base material 101 and within 25 mm from the boundary 103, the difference between the residual stress on the front surface 101a side and the residual stress on the back surface side is large, and the difference in residual stress is particularly large in the region that is 12 mm or more away from the boundary and within 17 mm from the boundary 103. In this embodiment, by performing rolling using the reduction roll 2 on the region where the difference in residual stress between the front surface 101a and the back surface 101b is large, the difference in residual stress between the front surface 101a and the back surface 101b becomes smaller, and the buckling deformation can be eliminated.

[0027] As described above, according to this embodiment, the buckling deformation in the butt welded joint 100 can be corrected by rolling the region R 10 to 25 mm away from the boundary 103 between the welded portion 102 and the base metal 101 from both sides in the thickness direction of the base metal 101 with the rolling rolls 2. Moreover, the correction method of this embodiment can perform sufficient correction compared to the conventional correction method using roll pressure. Furthermore, since this embodiment does not require heating the base metal 101, it can be suitably applied to the butt welded joint 100 made of stainless steel plate. Furthermore, since this embodiment does not involve hammering the base metal 101, no skill is required from the worker, and it can also handle welding deformations of complex shapes.

[0028] Second Embodiment Next, a second embodiment of the present invention will be described with reference to the drawings. An example of a welded joint that can be subjected to the correction method of this embodiment is a welded joint 200 as shown in Fig. 6. The welded joint 200 shown in Fig. 6 includes a pair of base materials 101 made of stainless steel plates and a welded portion 102. The welded joint 200 shown in Fig. 6 has angular deformation as well as buckling deformation after butt welding. The buckling deformation is a welding deformation in which the base material 101 curves along the longitudinal direction of the welded portion 102 so as to protrude toward the welding torch. The angular deformation is a welding deformation in which the welded portion 102 is deformed into a V-shape with the welded portion 102 as a valley line.

[0029] Next, the straightening method of this embodiment will be described. Fig. 7 and Fig. 8 are diagrams for explaining the straightening device and the straightening method of this embodiment. In the straightening method of this embodiment, as shown in Figs. 7 and 8, a straightening device 10 is used that is equipped with a rolling roll 2 similar to that of the first embodiment and a straightening roll 3 for pressing the welded portion 102. The straightening roll 3 for pressing the welded portion 102 is configured to press the welded portion 102 along the longitudinal direction of the welded portion 102. The straightening roll 3 is a crown roll whose roll surface 3a bulges in an arc shape. In the straightening device 10, the direction of the arrow X is the transport direction of the welded joint 200 as shown in Fig. 8.

[0030] In addition, when the welded joint 200 is long in the weld line direction, the straightening device 10 may be provided with a support roll 5 that supports the welded joint 200 from the underside in front of and / or behind the conveying direction X (weld line direction) of the welded joint of the rolling roll 2, as shown in FIG. 8.

[0031] In addition, as shown in FIG. 8, the position of the straightening roll 3 is preferably aligned with the rolling roll 2 when viewed from a direction perpendicular to the conveying direction X of the welded joint 200. The positions of the rolling roll 2 and the straightening roll 3 are based on the contact positions where the rolls 2 and 3 contact the base material 101, and the contact positions may be aligned at the same position when viewed from a direction perpendicular to the conveying direction X of the welded joint 200. By making the position of the straightening roll 3 the same as the position of the rolling roll 2, the straightening of the angular deformation by the straightening roll 3 can be performed simultaneously with the straightening of the buckling deformation by the rolling roll 2. The position of the straightening roll 3 does not need to be exactly the same as the position of the rolling roll 2. For example, the position of the straightening roll 3 may be shifted from the position of the rolling roll 2 within a range of 10 mm.

[0032] The correction method of this embodiment is performed in the same manner as in the first embodiment. That is, the rolling rolls 2 are brought into contact with the base metal 101 from both sides in the plate thickness direction of the base metal 101, and the base metal 101 is rolled along the longitudinal direction of the welded portion 102, thereby correcting the welding deformation. The pair of base metals 101 on both sides of the welded portion 102 in the width direction are rolled simultaneously. The area in which the rolling rolls 2 are brought into contact is within a region R that is 10 mm or more away from the boundary 103 between the welded portion 102 and the base metal 101 on the surface 101a of the base metal 101, and is within 25 mm from the boundary 103. The reduction rate by the rolling rolls 2 is in the range of 0.5 to 2.0%.

[0033] In the straightening method of the present embodiment, during rolling by the reduction rolls 2, the distance M between the boundary side end face 2a of the reduction roll 2 and the boundary 103 is kept at a distance equal to or greater than the thickness of the base material.

[0034] Further, in this embodiment, as shown in Figs. 7 and 8, the straightening roll 3 presses the welded portion 102 from the side where the welded portion 102 protrudes due to the angular distortion. Since the base material 101 on both sides of the welded portion 102 is constrained by the rolling roll 2, pressing the welded portion 102 with the straightening roll 3 generates a reverse bending deformation with respect to the angular distortion. In order to generate the reverse bending deformation, the height of the straightening roll 3 may be set to the same height as the lower rolling roll 2 or to a height equal to or greater than the height of the lower rolling roll 2 and not greater than the height of the lower rolling roll 2 + 2 mm. In this way, by generating a reverse bending deformation with respect to the angular distortion in the welded joint 200, it is possible to eliminate the angular distortion.

[0035] Furthermore, if the rolling roll 2 is too close to the welded portion 102, when the straightening roll 3 reversely bends the welded joint 200 to warp the base material 101 upward, there is a risk that the upwardly warped base material 101 will come into contact with the end face 2a of the upper rolling roll 2 on the opposite side of the straightening roll 3 across the welded joint 200. Therefore, when using the straightening roll 3 as in this embodiment, the distance M between the end face 2a on the boundary side of the rolling roll 2 and the boundary 103 is set to be at least equal to or greater than the plate thickness of the base material 101.

[0036] Fig. 9 shows a welded joint 210 after the correction. In the welded joint 210 shown in Fig. 9, the curvature of the base material 101 along the longitudinal direction of the welded portion 102 is eliminated, and the buckling deformation is corrected. In addition, the angular distortion is also eliminated.

[0037] As described above, according to this embodiment, the straightening roll 3 presses the welded portion 102 from the side where the welded portion 102 protrudes due to the angular distortion against the welded joint 200 being rolled by the rolling roll 2, thereby making it possible to simultaneously straighten the angular distortion as well as the buckling deformation. In addition, by setting the distance M between the end face 2a on the boundary side of the rolling roll 2 and the boundary 103 to a dimension equivalent to or greater than the plate thickness of the base material 101, it is possible to prevent the base material 101 of the welded joint 200 pressed by the straightening roll 3 from coming into contact with the end face 2a of the rolling roll 2 on the opposite side of the straightening roll 3 across the welded joint 200.

[0038] In the correction method of this embodiment, the case of correcting a welded joint 200 in which buckling deformation and angular distortion have occurred has been described; however, the object of correction in this embodiment is not particularly limited, and a welded joint in which only angular distortion has occurred may be the target.

[0039] (Third embodiment) Next, a third embodiment of the present invention will be described with reference to the drawings. The object of correction in this embodiment is, for example, a welded joint 200 in which buckling deformation and angular distortion occur, as in the second embodiment.

[0040] In this embodiment, a straightening jig 4 is used instead of the straightening roll 3 in the second embodiment. FIG. 10 and FIG. 11 are front and side views, respectively, for explaining the straightening device and the straightening method of this embodiment. The straightening device 20 shown in FIG. 10 and FIG. 11 is provided with a straightening jig 4 that presses the welded portion 102 from the side where the welded portion 102 protrudes due to angular deformation. The straightening jig 4 is configured to press the welded portion 102 from the back surface 101b side. Also, as shown in FIG. 10, the tip surface 4a of the straightening jig 4 when viewed from the conveyance direction of the welded joint is a curved surface that bulges in an arc shape. Also, as shown in FIG. 11, the tip surface 4a of the straightening jig 4 when viewed from the side in the conveyance direction of the welded joint is a curved surface that protrudes upward in an arc shape. This makes it possible to press the welded portion 102 while sliding the straightening jig 4 and the welded portion 102 relative to each other. A lubricant or the like may be applied between the correcting jig 4 and the welded portion 102 to improve sliding properties.

[0041] The correction method of this embodiment is performed in the same manner as in the first embodiment. That is, the rolling rolls 2 are brought into contact with the base material 101 from both sides in the thickness direction of the base material 101, and the welded joint 200 is conveyed in the conveying direction X while being rolled along the longitudinal direction of the welded portion 102, thereby correcting the welding deformation. The rolling is performed on each of a pair of base materials 101 on both sides in the width direction of the welded portion 102. The area in which the rolling rolls 2 are in contact is within a region R that is 10 mm or more away from the boundary 103 between the welded portion 102 and the base material 101 on the surface 101a of the base material 101 and within 25 mm from the boundary 103. During rolling by the rolling rolls 2, the distance between the end face 2a on the boundary side of the rolling roll 2 and the boundary 103 is kept at a distance equal to or greater than the dimension corresponding to the thickness of the base material 101. The reduction rate by the rolling rolls 2 is in the range of 0.5 to 2.0%.

[0042] Further, in this embodiment, as shown in Figs. 10 and 11, the welded portion 102 is pressed by the correction jig 4 from the side where the welded portion 102 protrudes due to the angular distortion, while being rolled by the rolling roll 2. Since the base material 101 on both sides of the welded portion 102 is constrained by the rolling roll 2, pressing the welded portion 102 by the correction jig 4 causes a reverse bending deformation with respect to the angular distortion. In order to cause the reverse bending deformation, the height of the correction jig 4 is set to the same height as the lower rolling roll 2 or to a height equal to or greater than the height of the lower rolling roll 2 and not greater than the height of the lower rolling roll 2 + 2 mm. In this way, by causing a reverse bending deformation with respect to the angular distortion in the welded joint 200, it is possible to eliminate the angular distortion.

[0043] After the correction, the welded joint has been corrected for buckling distortion and angular distortion.

[0044] As described above, according to this embodiment, the welded joint 200 being rolled by the rolling roll 2 is pressed against the welded part 102 by the correction jig 4 from the side where the welded part 102 protrudes due to the angular distortion, so that the angular distortion can be corrected simultaneously with the buckling deformation. In addition, by leaving a distance M between the end face 2a on the boundary side of the rolling roll 2 and the boundary 103 that is equal to or greater than the thickness of the base material 101, it is possible to prevent the base material 101 of the welded joint 200 pressed against the straightening roll 3 from coming into contact with the end face 2a of the rolling roll 2 on the opposite side of the straightening roll 3 across the welded joint 200.

[0045] The straightening jig 4 according to this embodiment is not limited to the one shown in Figures 10 and 11. For example, as shown in Figure 12, a straightening jig 44 having a length along the longitudinal direction of the welded portion 102 longer than the straightening jig 4 shown in Figures 10 and 11 may be used, the welded joint 200 may be placed on the straightening jig 44, and the welded joint 102 may be pressed by the straightening jig 44 while the roll roll 2 is moved in the direction of arrow Y relative to the straightening jig 44 and the welded joint 200 to roll them, thereby generating a reverse bending deformation in comparison with the angular deformation.

[0046] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described with reference to the drawings. An example of the correction target of this embodiment is a welded joint 300 as shown in Fig. 13. The welded joint 300 shown in Fig. 13 has angular distortion as well as buckling distortion after butt welding, similar to the welded joint shown in Fig. 6. The welded joint 300 shown in Fig. 13 has a larger amount of buckling distortion than the welded joint 200 shown in Fig. 6.

[0047] 14 to 17 are diagrams for explaining the straightening device and the straightening method of this embodiment. In the straightening method of this embodiment, as shown in FIG. 14 or 16, a straightening device 20 similar to that of the second embodiment is used. This straightening device 20 is equipped with a rolling roll 2 and a straightening roll 3 that presses the welded portion 102. The straightening roll 3 that presses the welded portion 102 is configured to press the welded portion 102 along the longitudinal direction of the welded portion 102. In addition, the straightening roll 3 is a crown roll whose roll surface 3a bulges in an arc shape.

[0048] In the correction method of this embodiment, a first step and a second step are performed in sequence. In the first step, as in the first embodiment, the rolling rolls 2 are brought into contact with the base material 101 from both sides in the thickness direction of the base material 101, and the base material 101 is rolled along the longitudinal direction of the welded portion 102, thereby correcting the welding deformation. In this first step, correction by the straightening roll 3 is not performed. Next, in the second step, as in the second embodiment, the rolling rolls 2 are brought into contact with the base material 101 from both sides in the thickness direction of the base material 101, and the base material 101 is rolled along the longitudinal direction of the welded portion 102, and the welded portion 102 is pressed by the straightening roll 3, thereby correcting the welding deformation.

[0049] It is preferable that the reduction rate by the reduction rolls 2 in the first step is in the range of 0.5 to 2.0%, and that the reduction rate by the reduction rolls 2 in the second step is in the range of 0.1 to 2.0%.

[0050] That is, in the first step, as shown in FIG. 14, the rolling rolls 2 are brought into contact with the base material 101 from both sides in the thickness direction of the base material 101, and the base material 101 is rolled along the longitudinal direction of the welded portion 102, thereby correcting the welding deformation. The pair of base materials 101 on both sides in the width direction of the welded portion 102 are rolled simultaneously. The area in which the rolling rolls 2 are in contact is within a region that is 10 mm or more away from the boundary 103 between the welded portion 102 and the base material 101 and within 25 mm from the boundary 103. During rolling by the rolling rolls 2, the interval M between the end face 2a on the boundary side of the rolling roll 2 and the boundary 103 is kept at a dimension equivalent to the thickness of the base material or more. In the first step, the correction roll 3 is kept retracted below the welded portion 102.

[0051] Fig. 15 shows a welded joint 310 after the first process. As shown in Fig. 15, the buckling deformation of the welded joint 310 after the first process has been completely or incompletely corrected by rolling with reduction rolls. Also, the angular distortion has been corrected to some extent but has not yet been completely corrected.

[0052] Next, in the second step, as shown in FIG. 16, the rolling rolls 2 are brought into contact with the base material 101 from both sides in the plate thickness direction of the base material 101, and the base material 101 is rolled along the longitudinal direction of the welded portion 102, and the straightening roll 3 presses the welded portion 102 from the side where the welded portion 102 protrudes due to angular deformation. The height of the straightening roll 3 may be the same as that of the second embodiment. The rolling conditions by the rolling roll 2 may be the same as those in the first step, or may be changed from those in the first step. For example, the rolling reduction in the second step may be lower than that in the first step within a range of 0.1 to 2.0%. The contact position of the rolling roll 2 in the second step may be different from the contact position in the first step, within a region 10 mm or more away from the boundary 203 and within 25 mm from the boundary 203.

[0053] Fig. 17 shows a welded joint 320 after the second step. As shown in Fig. 17, in the welded joint 320 after the second step, the buckling deformation is almost completely corrected by rolling with the reduction rolls 2. In addition, the angular distortion is also almost completely corrected.

[0054] In the straightening method of this embodiment, even when the amount of buckling deformation is particularly large and the angular distortion cannot be sufficiently corrected by the straightening roll 3, the amount of buckling deformation can be reduced by correcting the buckling deformation in the first step, so that the angular distortion can be reliably corrected using the straightening roll 3 in the subsequent second step.

[0055] As described above, according to the correction method of this embodiment, for a butt welded joint 300 in which both buckling deformation and angular distortion have occurred and the amount of buckling deformation has become large, a first step is performed in which the above-mentioned region R of the base material 101 is rolled with the reduction roll 2 to correct the buckling deformation, and then a second step is performed in which the above-mentioned region R of the base material 101 is rolled with the reduction roll 2 and the welded portion 102 is pressed with the correction roll 3, thereby correcting the buckling deformation and angular distortion and more reliably correcting the welding distortion.

[0056] In this embodiment, the straightening method using the straightening device 20 equipped with the straightening roll 3 has been described, but the present invention is not limited to this, and the straightening method of this embodiment may be performed using the straightening device 30 equipped with the straightening jigs 4, 44 as in the third embodiment. [Explanation of symbols]

[0057] 1, 10, 20, 30...straightening device, 2...rolling roll, 2a...end surface, 3...straightening roll, 4, 44...straightening jig, 100, 200, 300...butt welded joint, 101...base material, 101a...surface, 102...weld portion, 103 boundary, R...area.

Claims

1. A method for correcting a butt welded joint having a pair of base materials made of stainless steel plates and a welded portion, comprising the steps of: For each of the pair of base metals, a rolling roll is brought into contact with both sides of the base metal in a thickness direction within a region on the surface of the base metal that is 10 mm or more away from a boundary between the welded portion and the base metal and within 25 mm of the boundary, and the base metal is rolled along the longitudinal direction of the welded portion; A method for correcting a butt welded joint, in which a crown roll having a roll surface bulging in an arc shape is used as the rolling roll.

2. A method for correcting a butt welded joint comprising a pair of base materials made of stainless steel plates and a welded portion, comprising: For each of the pair of base metals, a rolling roll is brought into contact with both sides of the base metal in a thickness direction within a region on the surface of the base metal that is 10 mm or more away from a boundary between the welded portion and the base metal and within 25 mm of the boundary, and the base metal is rolled along the longitudinal direction of the welded portion; The welded portion is pressed by a straightening roll or a straightening jig from the side where the welded portion protrudes due to angular distortion against the butt welded joint being rolled by the rolling roll, a distance between the boundary end face of the rolling roll and the boundary is set to a dimension equal to or greater than a plate thickness of the base material during the rolling.

3. A method for correcting a butt welded joint as described in claim 1 or claim 2, wherein the reduction ratio in rolling the base material with the rolling rolls is 0.5 to 2.0%.

4. A method for correcting a butt welded joint having a pair of base materials made of stainless steel plates and a welded portion, comprising the steps of: a first step of rolling the base metal along the longitudinal direction of the weld by contacting a rolling roll with both sides of the base metal in a thickness direction of the base metal in a region of the base metal surface that is 10 mm or more away from a boundary between the weld and the base metal and within 25 mm of the boundary; a second step of rolling the base material along the longitudinal direction of the welded portion by the rolling rolls while contacting the region with rolling rolls from both sides in the plate thickness direction of the base material and pressing the welded portion with a straightening roll or a straightening tool from the side where the welded portion protrudes due to angular deformation; Equipped with A method for correcting a butt welded joint, wherein during the rolling in the first step and the second step, a distance between the end face of the rolling roll on the boundary side and the boundary is set to be equal to or greater than a dimension corresponding to a plate thickness of the base material.

5. In the rolling of the base material by the rolling rolls in the first step, a rolling reduction is set to 0.5 to 2.0%, The method for correcting a butt welded joint according to claim 4, wherein the rolling reduction rate in the rolling of the base material by the rolling rolls in the second step is 0.1 to 2.0%.

6. 6. The method for correcting a butt welded joint according to claim 2, wherein a crown roll having a roll surface bulging in an arc shape is used as the reduction roll.

7. A device for correcting a butt welded joint having a pair of base materials and a welded portion made of stainless steel plates, comprising: For each of the pair of base metals, a rolling roll is provided that contacts the base metal from both sides in a plate thickness direction within a region that is 10 mm or more away from a boundary between the welded portion and the base metal on the surface of the base metal and within 25 mm from the boundary, and rolls the welded portion along a longitudinal direction, 1 is a schematic diagram showing a straightening apparatus for a butt welded joint according to the first embodiment of the present invention;

8. A device for correcting a butt welded joint comprising a pair of base materials and a welded portion made of stainless steel plates, comprising: For each of the pair of base metals, a rolling roll is provided that contacts the base metal from both sides in a plate thickness direction within a region that is 10 mm or more away from a boundary between the welded portion and the base metal on the surface of the base metal and within 25 mm from the boundary, and rolls the welded portion along a longitudinal direction, A straightening device for a butt welded joint, comprising a straightening roll or a straightening tool that presses the welded portion from the side where the welded portion protrudes due to angular distortion against the welded joint being rolled by the rolling rolls.

9. 9. The apparatus for straightening a butt welded joint according to claim 8, wherein the reduction roll is a crown roll having a roll surface bulging in an arc shape.

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