WO1994007621A1

WO1994007621A1 - Method of forming welded pipe and forming stand therefor

Info

Publication number: WO1994007621A1
Application number: PCT/JP1993/001265
Authority: WO
Inventors: Kenji Hada; Yasuo Kimiya; Daigo Sumimoto
Original assignee: Nippon Steel Corporation
Priority date: 1992-09-25
Filing date: 1993-09-07
Publication date: 1994-04-14
Also published as: EP0623403A4; EP0623403B1; EP0623403A1; DE69327045T2; DE69327045D1

Abstract

A method of forming a welded pipe with high dimensional accuracy on a production line for the welded pipe, wherein a metal web having a predetermined width is continuously roll-formed and welded, and more particularly for bending the end portions of the metal web with high accuracy, and a forming stand therefor. A pair of top and bottom forming horizontal rolls or a forming horizontal roll, each split into two segments in the metal web width direction, can be each adjusted in position in the widthwise direction, and further, each split top roll segment has a construction capable of turning about and being fixed on a shaft disposed in the vertical direction. Further, in order to maximize the effect of the present invention, the direction of turning and the angle of turning are restricted. With the above-described arrangement, edge bending can be performed without impairing the accuracy in the wall thickness of the material to be formed, and further, common use of rolls for forming metal webs into pipes with different diameters is possible.

Description

Description Field of welding pipe forming method and forming stand technology

The present invention provides a method for continuously forming and welding a metal band having a predetermined width by an electric resistance welding method or other welding methods. The present invention relates to a molding method for molding a pipe and a molding stand. Conventional technology

Generally, in a manufacturing process for manufacturing a welded pipe such as an electric resistance welded steel pipe, a metal strip having a predetermined width is continuously formed into a forming roll group including a plurality of break-down rolls, side rolls, and fin pass rolls. Supplied and then manufactured by welding such as high frequency welding with squeeze rolls.

The major advantages of this method are high efficiency and low cost because it can be manufactured continuously. For this reason, they are widely used for pipes for machine structures, boiler pipes, oil well pipes, various pipes, etc. Recently, demands for thin-walled pipes, thick-walled pipes, high-strength pipes and the like have been increasing. In addition, there is a strong demand for high-dimensional pipes to ensure high dimensional accuracy.

However, when these thin-walled pipes, thick-walled pipes, and high-strength pipes are formed by a conventional method, defective shapes are generated. In other words, in forming in the pair of upper and lower break-down rolls in the initial forming process of edge forming, problems such as insufficient bending of the edge portion of the material to be formed arise.

On the other hand, during edge forming, the center The so-called W-bend method has been put to practical use, in which the vicinity is bent to the opposite curvature and the ends are bent to the same side as the product. For the effect of this method, see, for example, the Journal of the Japan Society for Technology of Plasticity.

It is introduced on page 519.

Japanese Patent Application Laid-Open No. 1-44217 discloses that a pilot hole horizontal roll of a forming stand for edge forming is composed of two rolls, and that the roll is inclined in a direction in which the metal strip advances. A method is described in which the angle can be adjusted so that the edge portion can be sufficiently formed in both thick and thin materials.

On the other hand, in the process of manufacturing such metal pipes by mouth forming and welding, the objectives are to reduce roll costs by reducing the number of hand-held rolls, and to improve the line operation rate by reducing the frequency of changing sockets. In addition, there is a demand for a molding port that can be used for rolls for metal strips having different pipe diameters. On the other hand, a roll as disclosed in JP-A-62-166027 has been devised and put into practical use.

As described above, break down rolls that perform edge forming in the conventional forming method have a problem of poor shape, especially when trying to form thin-walled tubes, thick-walled tubes, or high-tensile tubes. . In order to solve this shape defect, if the edge forming is intended to be strengthened by a later-fins roll, the wall thickness 1 of the edge as shown in Fig. 1 becomes large. This is a factor that hinders dimensional accuracy.

In addition, in the case of the W-bend break down roll, the edge portion can be bent more than in the conventional method because the bending force of the edge portion can be sufficiently ensured. In the forming process from the point of contact between the upper roll and the upper roll to just below the roll, the upper roll and the material to be formed are in local contact, so that indentations 2 as shown in Fig. 2 are likely to occur. This is a factor that hinders wall thickness accuracy. Furthermore, even this method cannot fundamentally solve the shape defect when forming a thick-walled tube or a thin-walled tube that is larger or smaller than the designed thickness of the upper roll 3 to some extent. As a result, the range of common use of molding thickness has not been expanded.

On the other hand, in Japanese Patent Application Laid-Open No. Hei 11-44217, the contact between the material to be formed and the roll is continuously changed as compared with the ordinary edge forming method. Although it can be expected, the range of commonality is limited due to the structure that crosses and lowers only the lower roll.

On the other hand, the roll disclosed in Japanese Patent Application Laid-Open No. 62-66027 has a roll-sharing property in a wide range of tube outer diameters, and since the roll curvature changes continuously, the contact between the metal band and the roll is localized. It is not suitable for forming thick-walled pipes because it tends to be a target and has problems such as poor shape. Disclosure of the invention

The present invention has been made in order to solve such problems of the prior art, and it is possible to form a welded pipe having good dimensional accuracy in a welded pipe manufacturing line. The purpose of the present invention is to provide a molding method and a molding stand capable of accurately bending a steel sheet, and the gist is as follows.

(1) In a method of bending a metal band end at a manufacturing line of a welded pipe for forming and welding a metal having a predetermined width, a pair of upper and lower horizontal rolls, each of which is bisected in the width direction of the metal band, are vertically A method for forming a welded pipe, wherein the metal is formed in a state where the pipe is crossed up and down as a turning axis.

(2) In the pair of upper and lower forming horizontal roll, turn angle u of the upper rolls, and the turning angle o _d a lower roll, and the turning direction of the upper and lower rolls, respectively Re its opposite, and, au ≤45 °

d ≤30 °

However, a _u : the angle formed by the metal band width direction axis and the roll axis of the horizontal upper roll a _d : the angle formed by the metal band width direction axis and the roll of the horizontal lower roll is set within the range described in (1). Forming method for welded steel pipe.

(3) In the pair of upper and lower forming horizontal rolls, the upper roll is directed to the edge side of the metal band at the entrance side of the mouth and the center side of the metal band at the exit side of the roll stand. The method of forming a welded pipe according to (1) or (2), wherein the turning angle is set.

(4) Roll forming and welding of a metal band with a predetermined width In the method of bending the metal band end at a welding pipe manufacturing line, each of the upper horizontal rolls divided in the metal band width direction is turned vertically. A method for forming a welded steel pipe, comprising forming a metal strip while rotating as a shaft-fixed.

(5) In the upper horizontal roll, the turning angle a _u of the upper horizontal roll is given by u ≤ 45

However, o _u: setting a range of the angle of the roll shaft of the metal带幅axis and the horizontal on the roll (4) molding method welded pipe according.

(6) In the upper horizontal roll, the turning angle is set so that the entrance side of the roll stand faces the edge side of the metal band, and the exit side of the roll stand faces the center side of the metal band. (4) or ( 5) The method for forming a welded steel pipe according to the above.

(7) In a method for bending a metal band end in a production line of a welded pipe for roll forming and welding a metal wire having a predetermined width, a pair of upper and lower horizontal rolls, each of which is bisected in the metal band width direction, is formed by a metal band. A method for forming a welded steel pipe, wherein the metal strip is formed in a state where the metal strip is arranged at a position different from the forming direction and crosses vertically with a vertical axis as a rotation axis.

(8) Manufacturing line for welding pipes for forming and welding metal In the initial forming roll group, a pair of upper and lower horizontal rolls for bending at the end of the metal band are divided into two in the width direction of the metal band, and each of the upper and lower rolls on both sides has a vertical axis as a pivot axis. A welding stand for forming a welded steel pipe, characterized in that it is possible to adjust the roll position and adjust the position in the sheet width direction.

(9) Manufacturing line for welded pipes to roll and weld a metal band of a predetermined width ・ In the initial forming roll group, the upper horizontal hole for bending the end of the metal band is divided into two parts in the width direction of the metal band. The upper roll is capable of adjusting the roll position using the vertical direction as a rotation axis, and adjusting the position in the sheet width direction. .

(10) The forming stand for a welded pipe according to (8) or (9), wherein the two divided horizontal rolls are arranged at different positions in a metal forming direction. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view of a metal strip showing an example of an edge thickening that deteriorates dimensional accuracy.

FIG. 2 is a cross-sectional view showing an example of a bending indentation that deteriorates dimensional accuracy. FIG. 3 is a view showing the progress of metal band forming immediately below the roll. Fig. 4 shows examples of upper and lower roll gaps set according to the respective molding curvatures and wall thicknesses of the present invention. (A) In the case of thin wall, (b) In the case of small bending curvature (large diameter size), (C) Thick wall; (d) Large bending curvature (small diameter).

FIG. 5 shows the roll direction, (a) is an example of an inward molding die in the present invention, and (b) is an example of an outward molding die in the present invention.

FIG. 6 is a view showing a thruster direction in the inward molding die of the present invention. FIG. 7 shows an example in which the upper roll deflects in the outward molding die according to the present invention.

FIG. 8 is a (a) front view and (b) a plan view of an example of a roll to which the present invention is applied.

FIG. 9 is a view showing an example of a molding apparatus to which the present invention is applied.

FIG. 10 is a diagram showing an example of a curvature and a thickness distribution after single-stand molding when the present invention is applied and when it is not applied.

FIG. 11 is a diagram showing an example of a curvature and a wall thickness distribution indicating roll sharability when the present invention is applied.

FIG. 12 is (a) a front view and (b) a plan view of a roll example to which the present invention is applied.

FIG. 13 is a view showing an example of a molding apparatus to which the present invention is applied. BEST MODE FOR CARRYING OUT THE INVENTION

In the present invention, as shown in FIG. 8, a break-down stand for edge forming is divided into two in the width direction of a metal to be formed and arranged on both sides. A pair of upper and lower forming horizontal rolls, each for edge forming, are vertically intersected with the vertical axis as the axis of rotation. It is possible to mold with high accuracy. This is because, as shown in FIG. 3, by crossing a pair of upper and lower forming horizontal rolls 3 and 4, the upper and lower rolls 3 and 4 are located on both sides of the bent portion of the metal band 5 to be formed in the vicinity immediately below the rolls. This is because the contact is formed more continuously so that local contact does not occur in the molding process as in the conventional method. Also, as shown in Fig. 4 (a) to (c), (a) thin wall, (b) small bending curvature (large diameter size), and (c) thick wall , Change the turning angle of upper roll 3 As a result, the curvature formed by the upper roll history immediately below the roll changes, so that a gear history corresponding to the thickness of the metal band as the material to be formed can be formed, and the thin material can be used. It is possible to mold with high accuracy in the thickness range up to thick materials.

In addition, as shown in Fig. 4 (d), (d) as in the case of large bending curvature (small diameter size), changing the turning angle of the lower roll changes the metal band to be formed. The curvature formed by the lower roll contacting the outer surface is changed, and the position of the pair of upper and lower rolls installed on both sides in the sheet width direction is adjusted according to the width of the metal band as the material to be formed. This allows rolls to be shared with metal strips with different pipe diameters.

In general, the turning angle of the upper roll is determined by the hole shape of the upper roll, the forming outer diameter of the metal, the thickness of the metal strip, the diameter of the upper roll, and the like. It is determined by the shape of the hole, the outer diameter of the metal band, the diameter of the lower roll, etc. In the second invention of the present invention, in order to maximize the effect of the present invention, Was limited as follows.

It is necessary to increase the turning angle of the upper roll as the forming thickness of the metal strip becomes thinner.However, if the turning angle is excessive, the slip between the upper roll and the metal strip becomes excessive, resulting in forming scratches, roll seizure, The upper limit of the swivel angle was set to 45 ° in consideration of the shared range of metal strips, as this could cause a reduction in roll life.

In addition, by increasing the turning angle of the lower roll, the range of common use of the forming outer diameter of the metal strip is widened.However, an excessive turning angle causes the same problem as described above. Since the range is limited by the interference of the metal strip, the upper limit of the turning angle is set to 30 ° in consideration of the common range of the forming outer diameter of the metal strip. As a result, about 1.5 to 2 times the outer diameter commonality is obtained. be able to.

Further, in the present invention, the upper and lower rolls are arranged at different positions in the metal band forming direction, so that the bending of one end of the metal band is started and then the bending of the other end. This eliminates the restriction on the turning angle due to the rolls on both sides drying out when the upper and lower rolls are turned, especially in the case of small diameters. In this case, the interval between the upper and lower rolls on both sides in the metal band forming direction is determined by the upper and lower roll diameters and the design rotation angle range.

Next, a case where only the upper horizontal roll is divided into two will be described.

The upper horizontal forming roll, which is divided into two parts in the width direction of the metal strip as the material to be formed and arranged on both sides, is used for edge forming. By forming the metal strip in the closed state, it is possible to form thin and thick pipes with good dimensional accuracy. This is because, as shown in Fig. 3, by turning the upper forming horizontal roll, the upper roll 3 comes into continuous contact from both sides of the bent portion of the metal band to be formed in the vicinity immediately below the roll. The reason for this is that local contact does not occur during the molding process as in the conventional method. Also, as shown in FIGS. 4 (a) to 4 (c), by changing the turning angle of the upper roll 3, the curvature formed by the upper roll history immediately below the roll changes, so The gap history can be configured according to the thickness of the metal strip as the forming material, and it is possible to form the material with high precision in the thickness range from the thin material to the thick material.

The turning angle of the upper roll is determined by the hole shape of the upper roll, the forming outer diameter of the metal strip, the thickness of the metal strip, the diameter of the upper roll, and the like. In the fifth invention of the present invention, In order to maximize the effect of the invention, the turning angle direction of the upper roll is limited as follows. It is necessary to increase the turning angle of the upper roll as the forming thickness of the metal strip becomes thinner.However, if the turning angle is excessive, the slip between the upper roll and the metal strip becomes excessive, resulting in forming scratches, roll seizure, The upper limit of the swivel angle was set to 45 ° in consideration of the common range of the thickness of the metal strip, as this may cause a reduction in roll life.

Next, the roll direction will be described. When the upper and lower rolls are swiveled in the upper and lower rolls, a force may be applied to the rolls in the width direction of the metal due to the slip between the rolls and the metal band, causing runout. For example, as shown in Fig. 5 (a), the upper roll is set so that the entry side of the roll stand points to the edge of the metal strip and the exit side faces the center side of the metal strip, and the lower roll sets the turning direction. When the upper and lower rolls cross each other by setting the reverse direction (in this case, the contact point of the upper roll shifts from the edge of the metal band to the inside, so hereafter it is referred to as the inward forming die) In this case, however, as shown in Fig. 6, an inward thrust is generated on the upper roll and an outward thrust is generated on the lower roll. In addition, the upper roll generates an outward deflection in the width direction, and the lower roll generates an inward deflection in the width direction. On the other hand, as shown in Fig. 5 (b), the upper roll is set so that the entry side of the roll stand faces the center side of the metal band and the exit side faces the edge side of the metal band, and the lower roll is the turning direction. When the upper and lower rolls intersect by setting them in the opposite direction (in this case, since the contact point of the upper roll shifts from the inside of the metal band to the edge, it is hereinafter referred to as an outward forming die) As shown in Fig. 7, the upper roll has a widthwise inward deflection and the lower roll has a widthwise outward deflection. Here, in the case of the outward molding die, the upper roll does not come into contact with the outermost edge, so that the edge portion is insufficiently bent, and when the present invention is applied to the W-bend method, it is accompanied by runout. There may be cases such as local wall thinning due to the narrowing of the gap. On the other hand, in the inward molding die, there is no concern about the above-mentioned problems, and the run-out force of the upper and lower rolls acts in a direction advantageous for edge forming, and advantages such as reduction of the rolling force of the upper and lower rolls can be expected. Therefore, it is desirable to use an inward molding die especially for a stand where run-out is likely to occur due to the rigidity of the stand and the like.

The above description is basically the same in the case where only the upper roll is turned, and it is more advantageous to use an inward molding die.

Hereinafter, the present invention will be described in detail with reference to the drawings based on examples.

Example 1

FIG. 8 shows (a) a front view and (b) a plan view of an example of a roll to which the present invention is applied. Here, the lower roll 4, depending on the molding curvature of the edge portion 13 of the metal strip 5 that will be formed, the turning angle QT _d is determined. In addition, the position in the width direction of the upper and lower rolls on both sides is determined according to the plate width and the bending length of the metal strip. Further, the turning angle a _u of the upper opening 3 is determined according to the thickness of the metal 5.

When the turning angle is set according to the thickness and bending curvature of the metal band at this time. -The history of the roll gap immediately below the roll is as shown in Fig. 4, and the deformation of the metal band according to the history of the roll gear is as shown in Fig. 3, where 3 is the upper roll. , 4 is the lower roll, 5 is the metal strip, and 7 is the center of the metal strip.

FIG. 9 is a front view of an example of an edge bend stand to which the present invention is applied. The roll support beam members 14 and 15 vertically hold the upper and lower roll bearing members 17 and 18, respectively, and the upper roll support beam member 14 can be moved and fixed in the vertical direction by the screw down screw shaft 16. It has a simple structure. The upper and lower roll supports 19, 20 are rotated by screw shafts (not shown) or rails (not shown) installed in the beam members 14, 15, respectively. It has a structure that can be moved and fixed in the width direction by sliding the light bracket. Further, the upper and lower roll supports 19, 20 have a structure capable of turning and fixing around a vertical axis by a method such as gear driving not shown.

In addition, if necessary, it is possible to adopt a structure in which the upper and lower rolls at the center in the width direction of the plate, or the bearing material that supports either the upper and lower rolls, are fixed to the roll support beam members 14 and 15. It is.

In this embodiment, an example is shown in which a pair of upper and lower horizontal rolls on both sides are arranged in the same stand. However, as in the seventh invention of the present invention, the horizontal rolls are installed at different positions. When the bending of the other end is started after the bending of the end of the other end, it may be arranged as a separate stand depending on the distance between both sides. Furthermore, it is also possible to install a guide roll on the side where the end bending is not performed.

FIG. 10 shows the case where the present invention is applied and the case where the present invention is not applied to the edge forming of a band equivalent to a yield stress of 294 NZ mm ² , φ50.8 Χt 2 and 10 mm, respectively. This figure shows the curvature distribution and wall thickness distribution after single-stand molding in this case. This example shows an example in which an inward molding die is applied. In the conventional method, insufficient bending occurs in a thin material, and an indentation occurs in a bent portion in a thick material. However, a very good shape is obtained by applying the present invention.

Furthermore, Fig. 11 shows the edge forging of the same material with a band equivalent to 34.0 Xt 5 mm by adjusting the turning angle using the same roll as above. The curvature and wall thickness distribution are shown later. It is molded almost according to the set curvature, and has good shape. It can be seen that by applying the present invention, the roll outer diameter is shared.

Table 1 shows the curvature and thickness reduction when molding was performed using the same roll and changing the turning angle of the upper and lower rolls for various forming outer diameters and wall thicknesses. It shows the performance of the generation. It can be seen that by applying the present invention, an improvement in edge formability, a reduction in wall thickness reduction, and a common use of a roll outer diameter are obtained. Further, it is understood that the effects of the present invention can be maximized by applying the second and third inventions of the present invention to the turning angle setting condition.

Table 1

*) The ratio of the bending curve ^ H precious value to the bending curve and the pipe value (pi-curvature)

Average in the 'edge bend' region

R o / R (R o: bending curvature 圣 target value, R: bending curvature ^ ί 圣 male value) **) Example 2

FIG. 12 shows (a) a front view and (b) a plan view of an example of a roll to which the present invention is applied. Here, the position of the lower roll 4 in the upper and lower roll width directions on both sides is determined according to the sheet width and the bending length of the metal member 5 to be formed. Further, the turning angle ctu of the upper roll 3 is determined according to the thickness of the metal strip 5. 7 shows the center of the metal strip.

At this time, when the turning angle is set according to the thickness and bending curvature of the metal band, the history of the upper roll gap near immediately below the roll is as shown in upper roll 3 in Fig. 4, and the lower roll is a normal roll. It will be the same as the one. The deformation of the metal strip according to the history of the roll gap is as shown in Fig. 3, where 3 is the upper roll, 4 is the lower roll, and 5 is the metal strip. FIG. 13 shows a front view of an example of an edge bend stand to which the present finding is applied. The roll support beam member 14 vertically holds the upper roll {receiving material}, and the upper roll support beam member 14 can be moved and fixed in the vertical direction by the screw down screw shaft 16. It has become. In addition, the upper roll support base 19 can be moved and fixed in the width direction by rotating a screw shaft (not shown) or sliding a slide bracket on a rail (not shown) installed in the beam member 14. It has become. Further, the upper roll support 19 has a structure that can be turned and fixed around a vertical axis by a method such as gear driving not shown. On the other hand, the lower roll 4 can be rotated by a lower roll 20 via a lower roll receiving member 18, and furthermore, its position can be changed in the width direction by a screw mechanism or a hydraulic mechanism (not shown). It has a structure that can be fixed.

If necessary, it is also possible to adopt a structure in which the supporting member for supporting the central upper roll is fixed to the upper roll supporting beam member 14 at the central portion in the plate width direction.

It should be noted that the yield stress 294 Ν Roh ^{mm 2, ^ 50. 8 X} t 2, 1 0 mm equivalent of带鐧 According to the results of the curvature distribution and wall thickness distribution after single-stand molding when the present invention is applied to edge forming and when it is not applied, the conventional method shows bending with thin material. Insufficient, thick-walled material has bent part indentations, but with the application of the present invention, a very good shape was obtained.

Table 2 shows the results of the curvature and the wall thickness reduction when forming was performed using the same roll and changing the turning angle of the upper roll for various forming wall thicknesses. It can be seen that by applying the present invention, improvement in edge formability and reduction in wall thickness reduction are realized. Furthermore, it is understood that the effects of the present invention can be maximized by applying the turning angle setting conditions to the fifth and sixth inventions of the present invention.

Table 2

*) The average of the ratio of the actual value of the bending curvature to the target bending curvature (tube product curvature) in the edge bending area

R o Z R (R 0: Target value of bending radius of curvature, R: Actual value of bending radius of curvature) **)

As described above, according to the present invention, when a metal strip is continuously roll-formed and welded to produce a welded pipe, a break-down roll device in an initial forming process for edge forming is used. Edge bending can be performed without impairing the wall thickness accuracy of the material to be formed, and the roll can be used for forming metal strips with different pipe diameters. effective.

Claims

The scope of the claims

1. In the metal band end bending method for the production line of a welded pipe in which a metal band having a predetermined width is roll-formed and welded, a pair of upper and lower horizontal rolls, each of which is bisected in the metal band width direction, is vertically oriented. A method for forming a welded pipe, characterized in that a metal pipe is formed in a state of being vertically crossed as a turning axis.

2. In the upper and lower pair of forming horizontal roll, turn angle au upper rolls, and the turning angle o _d a lower roll, and the turning direction of the upper and lower rolls, respectively Re its opposite, and,

u ≤ 45 ⁰

a _d ≤30 °

However, or _u : the angle between the metal band width direction axis and the roll axis of the upper horizontal roll α _ά : the angle _{between the} metal 带 width axis and the horizontal lower roll axis Method of forming steel pipe.

3. In the pair of upper and lower forming horizontal rolls, the upper roll faces the edge side of the metal band at the entrance side of the mouth and the center side of the metal band at the exit side of the mouth. Claim 1 or Set the turning angle to

2. The method for forming a welded steel pipe according to 2.

4. In the method of bending a metal band end at a production line of a welded pipe for roll forming and welding a metal band having a predetermined width, each of the upper horizontal rolls divided into two in the width direction of the metal band is pivoted in the vertical direction. A method for forming a welded steel pipe, comprising forming a metal strip while rotating and fixing the pipe.

5. In the horizontal on the roll, the turning angle o _u horizontal on the roll, au ≥ 45

Where or _{u is the} angle between the metal strip width direction axis and the horizontal upper roll. The method for forming a welded steel pipe according to claim 4, wherein the method is set in the range of:

6. The turning angle of the upper horizontal roll is set so as to face the edge of the metal band on the entrance side of the roll stand and the center side of the metal band on the exit side of the mouth stand. Or the method for forming a welded steel pipe described in 5 above,

7. In the method of bending a metal band end at a production line of a welded pipe for forming and welding a metal band having a predetermined width, a pair of upper and lower horizontal rolls, each of which is bisected in the width direction of the metal band, is formed by metal forming. A method for forming a welded steel pipe, wherein the metal pipe is formed in a state where the metal pipes are arranged at different positions in the direction and cross vertically with a vertical axis as a pivot axis.

8. Production line for welded pipes to roll and weld a metal band with a predetermined width ・ In the initial forming roll group, a pair of upper and lower horizontal rolls for bending the metal band end is divided into two in the width direction of the metal band. Further, each of the upper and lower rolls on both sides is capable of adjusting the roll position using the vertical direction as a rotation axis and the position adjustment in the sheet width direction, characterized in that it is characterized in that it is capable of adjusting the roll position. De.

9. Roll forming and welding of a metal strip with a predetermined width Line for manufacturing welded pipes ・ In the initial forming α-rule group, the upper horizontal hole for bending the metal end is formed in the width direction of the metal strip. Forming a welded steel pipe characterized in that it can be divided into two parts and placed on both sides of the line, and the upper roll can be used to adjust the roll position using the vertical axis as the axis of rotation and to adjust the position in the sheet width direction. stand.

10. The forming stand for a welded pipe according to claim 8, wherein the two divided horizontal rolls are arranged at different positions in a metal strip forming direction.