JP5355182B2 - Welded steel pipe manufacturing method and crushing equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that, in a conventional manufacturing method and a crushing equipment for a welded pipe, since a portion with an increased wall thickness is separated from an edge side face so that the amount of change in the thickness of the edge side face is small, the effect of a poor shape of an edge part to the thickness at a boundary portion between a weld bead and a base material part remains, so that the difference between the thicknesses of the boundary portion and of the base material part is made large. <P>SOLUTION: In the manufacturing method and the crushing equipment for a welded pipe, before forming an open-pipe, a notch-shaped step 30 is formed on the central part along the thickness direction of an edge side face 3a of a material steel strip 3 by pressing a stepped roll 41 against the edge side face 3a, and then the thickness of the edge side face 3a is increased by forcibly spreading the step 30. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a welded steel pipe manufacturing method and crushing equipment, and in particular, the influence on the thickness of the welded second part caused by the shape defect of the edge part can be further reduced, and the thickness of the welded second part and the thickness of the base metal part. The present invention relates to a new improvement for making the difference between and smaller.

  As a manufacturing method and crushing equipment for this type of welded steel pipe that has been conventionally used, for example, a method disclosed in Patent Document 1 or the like is used. FIG. 13 is a configuration diagram showing a conventional welded steel pipe production line. As shown in the figure, the welded steel pipe 1 is manufactured by passing the material strip 3 through the crushing equipment 4, the forming roll group 5, and the welding equipment 6 along the line direction 2. The crushing equipment 4 corrects the shape of the edge portion of the material strip 3. The forming roll group 5 is formed by gradually deforming the material strip steel 3 into a pipe shape to form the open pipe 7 in a state where the edge portions of the material strip steel 3 are abutted. The welding equipment 6 welds the butt portion of the open pipe 7 to form the welded steel pipe 1 from the open pipe 7.

  Next, FIG. 14 is a cross-sectional view of the edge portion of the material strip 3 of FIG. The raw steel strip 3 is obtained by cutting a steel plate into a strip shape according to each manufacturing dimension. As shown in FIG. 14, sagging 8 and burrs 9 (defective shape) due to plastic deformation at the time of cutting are formed on the edge portion of the material steel strip 3, and the edge side surface 3a is affected by these defective shapes. The thickness T1 is smaller than the thickness T2 of the base material portion. If the welded steel pipe 1 is formed in a state where these shape defects are left, the thickness in the vicinity of the weld bead becomes smaller than the thicknesses of the base material portion and the weld bead portion.

  The part where the thickness near the weld bead is small (the part at the boundary between the weld bead and the base metal) is generally referred to as weld No. 2, and the thickness of the weld No. 2 and the base depending on the use of the steel pipe. The allowable value of the difference from the thickness of the material part is specified. If the difference in thickness exceeds an allowable value, processing defects such as cracks occur during processing such as bending and pipe expansion. Further, if the difference in thickness exceeds the allowable value, a gap is formed in the vicinity of the weld bead portion, which becomes a base point for crevice corrosion in the stainless steel pipe. That is, the defective shape of the edge portion deteriorates the quality of the welded portion of the welded steel pipe 1.

  Next, FIG. 15 is explanatory drawing which shows the shape correction of the edge part of the raw steel strip 3 by the crushing equipment 4 of FIG. The crushing equipment 4 corrects the sagging 8 and the burrs 9 at the edge portion, thereby reducing the difference in thickness between the second welded portion and the base material portion. As shown in (a) of FIG. 15, the crushing equipment 4 is provided with a flat roll 4 a having a predetermined angle with respect to the vertical direction, and the flat roll 4 a is an edge side surface of the material steel strip 3. 3a is pressed. Since the flat roll 4a and the material strip 3 are in surface contact with each other at the edge side surface, the material is constrained and the deformability is low, and the deformation amount of the edge side surface portion by this processing is small. However, as shown in FIG. 15 (b), the thickness T4 of the part slightly away from the edge side surface 3a is increased, so that the weld thickness 2 at the time of butt welding can be made slightly larger than that of the unprocessed product. .

Japanese Patent Laid-Open No. 62-252585

  In the conventional welded steel pipe manufacturing method and crushing equipment as described above, the thickened part is a part away from the edge side surface, and the amount of change in the thickness of the edge side surface is small. The effect on the thickness of the number part remains, and the difference between the thickness of the welded number 2 part and the thickness of the base material part becomes large.

  The present invention has been made in order to solve the above-described problems, and the object of the present invention is to reduce the influence on the thickness of the welded second part caused by the defective shape of the edge part. It is an object of the present invention to provide a welded steel pipe manufacturing method and a crushing facility that can further reduce the difference between the thickness and the thickness of the base material portion.

The method for manufacturing a welded steel pipe according to the present invention is a method for manufacturing a welded steel pipe by manufacturing a welded steel pipe by welding a butt portion of an open pipe, and before forming the open pipe, the edge side surface of the material strip steel By pressing a stepped roll onto the edge side surface to form a notch-shaped step at the center along the thickness direction of the edge side surface, and pressing the flat roll against the edge side surface after the stepped processing. And a step of expanding the step to increase the thickness of the side surface of the welded steel pipe, wherein the stepped rolls are provided continuously with each other and one of the first and second is inclined with respect to the other. The joint portion of the first and second side surfaces is formed with a protrusion for forming the step at the central portion. A first steel strip end face located on the inner diameter side and a second steel strip end face located on the outer diameter side when provided as a pun pipe are provided, and the first and second side faces of the stepped roll are One side is inclined with respect to the other so that the second steel strip end face side forms a step projecting along the width direction of the raw steel strip compared to the first steel strip end face side. And

Further, the crushing equipment according to the present invention is a crushing equipment for correcting the shape of the edge portion of the material strip steel which is a material of the welded steel pipe, and is provided continuously with each other with respect to the other. A stepped roll having inclined first and second side surfaces, and a protrusion formed at a joint portion of the first and second side surfaces; and a stepped roll disposed at a rear stage of the stepped roll; A flat roll having a flat surface with a predetermined angle, and the stepped roll is pressed against the edge side surface of the material strip steel, thereby forming a notch-shaped step in the center portion along the thickness direction of the edge side surface. A stepping process is performed to form a step, and after the stepping process, a flat roll is pressed against the edge side surface to expand the step and increase the thickness of the edge side surface. A crushing equipment that is configured to, wherein the material steel strip, and a second steel strip end surfaces located in the first steel strip end surface and the outer diameter side positioned on the radially inner side when it is open the pipe The first and second side surfaces of the stepped roll are provided such that the second steel strip end face side protrudes along the width direction of the raw steel strip compared to the first steel strip end face side. One is inclined with respect to the other so as to form a step.

  According to the welded steel pipe manufacturing method and the crushing equipment of the present invention, the step formed on the edge side surface of the material strip steel is expanded to increase the thickness of the edge side surface. The amount of change can be increased. As a result, the influence on the thickness of the welded second part caused by the shape defect of the edge part can be made smaller, the difference between the thickness of the welded second part and the thickness of the base material part can be made smaller, and a higher quality welded part. Can be obtained.

The stepped roll has first and second side surfaces that are provided continuously with each other and are inclined with respect to the other, and the joint portion between the first and second side surfaces includes the first and second side surfaces. Since the protrusion for forming the step is formed at the center, a notch-shaped step can be more reliably formed at the center of the edge side surface, and a high-quality weld can be obtained more reliably.
Moreover, the said 1st and 2nd side surface of the said stepped roll forms the said level | step difference by which the said 2nd steel strip end surface side protruded along the width direction of the said raw steel strip compared with the said 1st strip steel end surface side. As one of them is inclined with respect to the other, the circumferential length difference between the outer diameter side and the inner diameter side can be canceled more reliably, and the edge side surfaces can be abutted in parallel. Can be obtained.

It is a front view which shows the crushing apparatus by Embodiment 1 of this invention. It is sectional drawing of the stepped roll of FIG. It is explanatory drawing which shows the step processing by the step roll of FIG. It is explanatory drawing which shows the shape correction by the flat roll of FIG. It is sectional drawing of the butt | matching part of an open pipe using the raw material strip steel in which shape correction is not given. It is sectional drawing of the butt | matching part of the open pipe using the raw material strip steel in which the conventional shape correction was performed. It is sectional drawing of the butt | matching part of the open pipe using the raw material strip steel in which the shape correction of embodiment was performed. FIG. 8 is a graph showing the thickness at the butting portion of FIGS. It is sectional drawing of the welding part which welded the butt | matching part of FIG. It is sectional drawing of the welding part which welded the butt | matching part of FIG. It is sectional drawing of the welding part which welded the butt | matching part of FIG. It is a graph which shows the thickness of the welding part of FIGS. It is a block diagram which shows the manufacturing line of the conventional welded steel pipe. It is sectional drawing of the edge part of the raw material strip steel of FIG. It is explanatory drawing which shows the shape correction of the edge part of the raw material strip steel by the crushing equipment of FIG.

The best mode for carrying out the present invention will be described below with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a front view showing a crushing device 40 according to Embodiment 1 of the present invention. In addition, the same code | symbol is demonstrated about the part which is the same as that of a conventional structure, or an equivalent. In the figure, the crushing device 40 corrects the shape of the edge portion of the material steel strip 3, and is installed in the front stage of a forming roll group (see FIG. 13) for forming an open pipe. The crushing apparatus 40 of this embodiment is provided with a stepped roll 41 and a flat roll 4a. The stepped roll 41 is a roll provided with a protrusion (see FIG. 2) on the side surface, and is disposed in front of the flat roll 4a. The flat roll 4a is a roll whose side surface is a flat surface having a predetermined angle with respect to the vertical direction. As will be described later, each roll 41, 4 a is pressed against the edge side surface 3 a of the material strip 3.

  Next, FIG. 2 is a cross-sectional view of the stepped roll 41 of FIG. In FIG. 2, the cross section of one half of the stepped roll 41 is omitted with the rotation axis as the center. In the figure, the stepped roll 41 has first and second side surfaces 41a and 41b provided continuously with each other. One of the first and second side surfaces 41a and 41b is provided so as to be inclined with respect to the other so as to form a protrusion 41c at the joint portion. In this embodiment, the first side surface 41a extends along the vertical direction, and the second side surface 41b is provided with an inclination of 30 ° toward the inner diameter side with respect to the first side surface 41a. The protrusion 41 c is provided so as to be located at the center along the thickness direction of the material strip steel 3.

  Next, the shape correction of the edge part of the raw steel strip 3 by the crushing device 40 will be described. FIG. 3 is an explanatory view showing the step processing by the step roll 41 of FIG. As shown in the figure, sagging 8 and burrs 9 due to plastic deformation at the time of cutting are formed at the edge portion of the raw steel strip 3 introduced into the crushing device 40, and the edge of the edge due to the influence of these shape defects. The thickness T1 of the side surface 3a is smaller than the thickness T2 of the base material portion. The crushing device 40 reduces the difference between the thickness T1 of the edge side surface 3a and the thickness T2 of the base material portion before the open pipe (FIG. 13) is formed. As shown in FIG. 3A, when the stepped roll 41 is pressed against the edge side surface 3a of the material steel strip 3, the meat at the center portion along the thickness direction of the edge side surface 3a is pushed out to the outside along the thickness direction. Thus, as shown in FIG. 3B, a notch-shaped step 30 is formed at the center of the edge side surface 3a. The notch-shaped step 30 is a recess having a V-shaped cross section.

  Here, the material steel strip 3 is provided with a first steel strip end face 31 located on the inner diameter side when the open pipe 7 is formed and a second steel strip end face 32 located on the outer diameter side. As described above, since the second side surface 41b of the stepped roll 41 is inclined toward the inner diameter side with respect to the first side surface 41a, the step 30 has a second band compared to the first band steel end surface 31 side. The steel end surface 32 side has a shape protruding along the width direction of the material steel strip 3.

  Next, FIG. 4 is explanatory drawing which shows the shape correction by the flat roll 4a of FIG. As shown in FIG. 4A, when the flat roll 4a is pressed against the edge side surface 3a of the material strip 3 after the step processing by the step roll 41, as shown in FIG. The step 30 is expanded. In the conventional method, the amount of deformation of the edge side surface 3a portion is small, and the thickness T4 (see FIG. 14) of the part away from the edge side surface 3a is increased. However, in the method of this embodiment, the step 30 is expanded. This reliably increases the thickness T1 of the edge side surface 3a.

Next, the effect of shape correction by the crushing device 40 will be described.
FIG. 5 is a cross-sectional view of the butted portion of the open pipe 7 using the material band steel 3 that has not been subjected to shape correction, and FIG. 6 uses the material band steel 3 that has been subjected to conventional shape correction. FIG. 7 is a cross-sectional view of a butt portion of the open pipe 7 using the material band steel 3 subjected to shape correction according to the embodiment. Moreover, FIG. 8 is a graph which shows the thickness in the butt | matching part of FIGS. The conventional shape correction is a correction method in which shape correction is performed only by the flat roll 4a without using the stepped roll 41. Further, SUS304 steel strip was used as the material steel strip, and the material of the rolls 4a and 41 was SKD11.

  As shown in FIGS. 5 and 8, when the open pipe 7 is formed using the material band steel 3 that has not been subjected to shape correction, the thickness T1 of the edge side surface 3a is compared with the thickness T2 of the base material portion. The thickness T3 at the position corresponding to the second welded portion was 0.94 times. Thus, when shape correction is not performed, the influence of the sagging 8 and the burrs 9 appears greatly in the thickness T1 of the edge side surface 3a, and the thickness T1 is reduced. Note that the position corresponding to the welded second part is a position that is considered to be located at the boundary between the weld bead and the base material when the butted part is welded.

  As shown in FIGS. 6 and 8, when an open pipe is formed using the material strip steel 3 subjected to conventional shape correction, the thickness T1 of the edge side surface 3a is compared with the thickness T2 of the base material portion. The thickness T3 at the position corresponding to the weld No. 2 was 0.97 times. As described above, when the shape correction according to the conventional method is performed, the sagging 8 and the burrs 9 are reduced, so that the thicknesses T1 and T3 are improved. However, the thickness T1 of the edge side surface 3a is still small, and the influence of the sagging 8 and the burrs 9 remains on the thickness T1 of the edge side surface 3a.

  As shown in FIGS. 7 and 8, when the open pipe is formed using the material strip steel 3 subjected to the shape correction according to the embodiment, the thickness of the edge side surface 3a is compared with the thickness T2 of the base material portion. T1 was 0.92 times, and the thickness T3 at the position corresponding to the weld second part was 0.98 times. Thus, when the shape correction of the embodiment is performed, the sagging 8 and the burrs 9 can be more reliably reduced, and further improvements can be confirmed in the thicknesses T1 and T3. In addition, as described above, the step 30 has a shape in which the second band steel end face 32 side protrudes along the width direction of the material band steel 3 as compared with the first band steel end face 31 side. The edge side surface 3a is abutted in parallel by canceling out the circumferential length difference between the side and the inner diameter side.

  Next, FIG. 9 is a cross-sectional view of the welded portion where the butted portion of FIG. 5 is welded, FIG. 10 is a cross-sectional view of the welded portion where the butted portion of FIG. 6 is welded, and FIG. It is sectional drawing of the welding part which welded the butt | matching part of 7. FIG. Moreover, FIG. 12 is a graph which shows the thickness of the welding part of FIGS. 9-11. As shown in FIGS. 9 and 12, when the butted portion of the open pipe 7 of the material steel strip 3 not subjected to shape correction is welded, the thickness of the weld bead 1a is compared with the thickness T2 of the base material portion. T1 ′ was 0.87 times, and the thickness T3 ′ of the weld second part was 0.91 times. As described above, when the shape correction is not performed, the thicknesses T1 'and T3' are small due to the influence of the small thicknesses T1 and T3 before welding. When such a welded steel pipe 1 is processed, there is a high possibility that processing defects such as cracks will occur.

  As shown in FIG. 10 and FIG. 12, when welding the butt portion of the open pipe 7 of the material band steel 3 subjected to shape correction of the conventional method, the weld bead 1a is compared with the thickness T2 of the base material portion. The thickness T1 ′ was 1.03 times, and the thickness T3 ′ of the second welded part was 0.97 times. Thus, the shape correction of the conventional method can reduce the difference between the thickness T3 ′ of the welded second part and the thickness T2 of the base metal part to some extent, but in order to obtain a higher quality welded steel pipe 1, the above difference is used. It needs to be even smaller.

  As shown in FIGS. 11 and 12, when welding the butt portion of the open pipe 7 of the material strip steel 3 subjected to the shape correction of the embodiment, the weld bead is compared with the thickness T2 of the base material portion. The thickness T1 ′ of 1a was 1.01 times, and the thickness T3 ′ of weld No. 2 was 0.99 times. As described above, when the shape correction according to the embodiment is performed, the difference between the thickness T3 ′ of the welded second portion and the thickness T2 of the base material portion can be extremely reduced, and a higher quality welded portion can be obtained. Can do.

  In such a welded steel pipe manufacturing method and crushing equipment 40, the step 30 formed on the edge side surface 3a of the raw steel strip 3 is expanded to increase the thickness of the edge side surface 3a. The thickness change amount of the side surface 3a can be increased. As a result, the influence on the thickness T3 ′ of the welded second part caused by the shape defect of the edge part can be further reduced, and the difference between the thickness T3 ′ of the welded second part and the thickness T2 of the base material part can be further reduced. High quality welds can be obtained.

  Further, the stepped roll 41 has first and second side surfaces 41a and 41b that are provided continuously with each other and inclined with respect to the other, and the first and second side surfaces 41a and 41b are joined to each other. Since the protrusion 41c for forming the step 30 is formed at the center of the edge side surface 3a in the portion, the step 30 can be formed more reliably, and a high-quality weld can be obtained more reliably. .

  Further, the first and second side surfaces 41 a and 41 b of the stepped roll 41 have a step 30 in which the second steel strip end face 32 side protrudes along the width direction of the raw steel strip 3 compared to the first steel strip end face 31 side. Since one side is inclined with respect to the other so as to form the edge side 3a, the edge side surface 3a can be abutted in parallel by canceling the circumferential length difference between the outer diameter side and the inner diameter side more reliably. A welded part can be obtained.

  In the embodiment, it has been described that the first side surface 41a of the stepped roll 41 extends along the vertical direction, and the second side surface 41b is inclined by 30 ° with respect to the first side surface 41a. The inclination angle of the first and second side surfaces is arbitrary as long as the protrusion can form a protrusion.

  In the embodiment, the crushing equipment 40 has been described to form a welded steel pipe production line together with the forming roll group 5 and the welding equipment 6. However, the crushing equipment is separate from the forming roll group and the welding equipment. It may be placed offline. That is, before the open pipe is formed by the forming roll group, the shape of the edge portion of the raw steel strip may be corrected in advance with a crushing facility offline.

DESCRIPTION OF SYMBOLS 1 Welded steel pipe 3 Material strip steel 3a Edge side surface 30 Level difference 31, 32 First and second strip steel end surface 7 Open pipe 40 Crushing device 4a Flat roll 41 Stepped roll 41a, 41b First and second side surface 41c Projection

Claims (2)

A welded steel pipe manufacturing method for manufacturing a welded steel pipe (1) by welding a butt portion of an open pipe (7),
Before forming the open pipe (7), the stepped roll (41) is pressed against the edge side surface (3a) of the material steel strip (3) to the central portion along the thickness direction of the edge side surface (3a). Stepping to form a notch-shaped step (30) is performed, and after the stepping, the step (30) is expanded by pressing a flat roll (4a) against the edge side surface (3a). a method for producing a welded steel pipe Ru increase the thickness of the edge side (3a),
The stepped roll (41) has first and second side surfaces (41a, 41b) that are provided continuously with each other and are inclined with respect to the other, and the first and second side surfaces ( 41a, 41b) is formed with a protrusion (41c) for forming the step (30) in the central portion at the joint portion,
The raw steel strip (3) includes a first steel strip end face (31) located on the inner diameter side when the open pipe (7) is formed, and a second steel strip end face (32) located on the outer diameter side. Is provided,
As for the said 1st and 2nd side surface (41a, 41b) of the said stepped roll (41), compared with the said 1st strip steel end surface (31) side, the said 2nd strip steel end surface (32) side is the said raw material strip ( 3) One is inclined with respect to the other so as to form the step (30) protruding along the width direction of 3)
The manufacturing method of the welded steel pipe characterized by the above-mentioned. Crushing equipment for correcting the shape of the edge of the steel strip (3) which is the material of the welded steel pipe (1),
The first and second side surfaces (41a, 41b), which are provided continuously with each other and are inclined with respect to the other, have protrusions on the joint portions of the first and second side surfaces (41a, 41b). A stepped roll (41) formed with 41c);
A flat roll (4a) disposed on the rear stage of the stepped roll (41) and having a side surface having a predetermined angle with respect to the vertical direction;
When the stepped roll (41) is pressed against the edge side surface (3a) of the material strip steel (3), a notch-shaped step (30) is formed in the central portion along the thickness direction of the edge side surface (3a). The step (30) is expanded by pressing the flat roll (4a) against the edge side surface (3a) after the step processing, and the thickness of the edge side surface (3a) is increased. there have a configuration which do torque lashing equipment as increased,
The raw steel strip (3) has a first steel strip end face (31) located on the inner diameter side when the open pipe (7) is formed and a second steel strip end face (32) located on the outer diameter side. Provided,
As for the said 1st and 2nd side surface (41a, 41b) of the said stepped roll (41), compared with the said 1st strip steel end surface (31) side, the said 2nd strip steel end surface (32) side is the said raw material strip ( 3) One is inclined with respect to the other so as to form the step (30) protruding along the width direction of 3)
Crushing equipment characterized by that.

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