JP2003251405A - Method for fabricating welded tube and device for pulling up seam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an equipment array for fabricating a welded tube by which edge waves before joining the edges of an open tube are stably prevented without interfering with another device to be inserted in a tube. <P>SOLUTION: Both edge parts 23a, 23b are pulled up in the direction (vertically upward) of an arrow 3 through a shoe 1, which is threaded through between both edge parts 23a, 23b of the open tube 23 passing through in the direction of an arrow 2 between the final fin pass rolls 21 of a forming roll group 8 and squeeze rolls 22 and is made in slidable contact with the inside surfaces of both edge parts 23a, 23b. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welded pipe manufacturing method and a seam pulling apparatus, and more particularly, to a round welded pipe by welding both edges of an open pipe formed into a substantially round shape by a roll forming method. TECHNICAL FIELD The present invention relates to a method for manufacturing an eggplant welded pipe and a seam pulling apparatus suitable for carrying out the method.

[0002]

2. Description of the Related Art In the process of manufacturing large-diameter welded pipes such as ERW steel pipes, a group of forming rolls consisting of breakdown rolls, cage rolls, fin pass rolls and the like and a squeeze roll are arranged in this order from the upstream side along a pipe making line. Placed manufacturing equipment is used. In this type of equipment, as shown in FIG. 3, both edges 23a and 23b of the open pipe 23 are approached from the outside of the open pipe 23 by a certain distance between the final fin pass roll 21 and the squeeze roll 22. The seam guide roll 24 is arranged to restrain the edge portions 23a, 23
While restraining b, he is guiding to squeeze roll 22.

However, in forming an electric resistance welded steel pipe, as shown in FIG.
The locus L1E that one point in the longitudinal direction of 25a, 25b follows from the state of the strip steel 25 to the state of the open pipe 23 is more than the locus L1C of one point in the central portion 25c of the strip width at the same position in the longitudinal direction of the material. Since the length becomes longer, both edge portions 25a and 25b of the strip steel 25 are in a state of edge stretch in which they are temporarily stretched.

Therefore, when the restraint force from the outside does not act, the open pipe 23 is bent in an annular shape with both edge portions 23a and 23b on the outer side. Since the pass roll 21 applies a reduction in the circumferential direction to both the edge portions 23a and 23b, a compressive stress is generated in the extended edge portions 23a and 23b. Due to this circumferential reduction, the open pipe 23
If the whole is not elongated in the longitudinal direction, both edge portions 23a and 23b of the open pipe 23 are buckled due to the compressive stress generated in the edge portion, so that a so-called edge wave in which the edge portion undulates is generated.

Before the two edges 23a, 23b of the open pipe 23 are butted to each other, that is, before welding, the edges 23a, 23b are welded.
If an edge wave is generated on either side of b, stable welding is not performed, and the phase of the edge waves of both edge portions 23a and 23b is not generally synchronized, so as shown in FIG.
There is a problem that a positional deviation (gap G) in the height direction occurs between the two edge portions 23a and 23b of the open pipe 23, which makes welding difficult.

The following techniques are known as solutions to this problem. [1] By giving downhill to the whole pipe making line,
While suppressing the elongation of the open pipe edge in the longitudinal direction,
Elongation is given to the bottom portion (the portion facing the edge portion) (JP-A-61-165225 and JP-A-61-165226). [2] For example, as shown in FIG. 6, the inner seam guide roll device 11 is arranged on the inner surface side of the open pipe 23 on the entrance side of the squeeze roll, and the push-up rolls 12a and 12b in the device 11 both edge portions 23a, The edge wave just before welding is apparently erased by pushing up 23b (JP-B-61-34908, JP-A-5-34908).
208213, JP-A-5-277757, JP-A-7-16760, JP-A
10-175014).

[0007]

However, the technique [1] cannot obtain a sufficient edge wave preventing effect. In addition, the entire pipe making line needs to be changed, which increases the cost. On the other hand, the technique of [2] provides a sufficient edge wave prevention effect.
In addition, the local cost of the pipe making line is sufficient, so the cost is not so high. However, in the technology of [2], the inner seam guide device is arranged on the inner surface side of the open pipe on the squeeze roll entry side, so space for other pipe interior entry devices (: inner bead cutting device, impeder, etc.) There is a problem that it occurs, and there is a problem that it is difficult to obtain a stable edge wave prevention effect because it is likely to be displaced due to interference with other devices due to vibration of the tube.

In view of the above-mentioned problem of the prior art [2], the present invention is a method for manufacturing a welded pipe capable of stably preventing an edge wave before joining an open pipe edge without interfering with other pipe interior filling devices. And a seam pulling device.

[0009]

The present invention has achieved the above object by pulling up both edge portions of an open pipe using an inner surface shoe on the squeeze roll entrance side (forming roll group exit side). That is, the present invention is a method for manufacturing a welded pipe in which a band steel is gradually width-bent formed by a forming roll group to form an open pipe, and both edge portions of the open pipe are welded while abutting each other with a squeeze roll. Between the group and the squeeze roll, the welded pipes are pulled up through the shoes which are slidably contacted with the inner surfaces of the both edge portions through the both edge portions. Is the way.

Further, the present invention is arranged between a group of forming rolls which are formed by gradually bending the strip steel to form an open pipe, and a squeeze roll which welds both edges of the open pipe while abutting each other. A seam pulling device, which slidably contacts the inner surfaces of the both edge portions and is supported on the outer surface side of the open pipe through the both edge portions, and an open pipe on a supported portion of the shoe. A seam pulling device comprising: elastic supporting means exerting an elastic pulling force from the outer surface side.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, "welding" means
It is a concept that includes not only ordinary melting but also solid phase diffusion below the melting point. As the welding method, a high energy beam welding method such as laser, high frequency electric resistance welding method, TIG, MIG, MAG and other welding methods, a welding method combining these methods, and a solid phase pressure welding method are preferably used. sell.

In the method of the present invention, for example, as shown in FIG. 1, both of the open pipes 23, which are passed in the direction of arrow 2, between the final fin pass roll 21 and the squeeze roll 22 of the forming roll group 8. The edge portions 23a and 23b are passed between the two edge portions.
The both edge portions 23a, 23b are pulled up in the direction of arrow 3 (vertically upward) via the shoe 1 slidably contacting the inner surfaces of 23a, 23b. According to this, by setting the pulling distance (pulling height) to an appropriate value (for example, the upper limit of the actual edge height), both edge portions 23a on the squeeze roll 22 entrance side,
The gap G between 23b (see FIG. 5) can be eliminated, and it becomes possible to manufacture the welded pipe 30 having no misalignment (step) in the product seam portion.

Further, the means for supporting the shoe 1 can be arranged outside the pipe, and the portion of the shoe 1 arranged inside the pipe may have a minimum size necessary for pulling up both edge portions. ] The problem of inconsistency in space with other pipe interior insertion devices and the problem of instability such as displacement due to interference with them do not occur. In addition, between the fin pass roll 21 and the squeeze roll 22, both edge portions 23a,
An edge heating device for heating 23b to a temperature at which welding is possible is provided, but its illustration is omitted.

The material of the shoe is not particularly limited, but plastics, ceramics and the like can be preferably used from the viewpoint of the rigidity of the material and the slidability with the inner surface of the tube. Further, in order to pull up both edge portions 23a, 23b to an appropriate height via the shoe 1, it is necessary to exert an attractive force in the direction of the arrow 3 on the shoe 1, which attractive force is, for example, a spring, a fluid pressure cylinder, or the like. It is preferably generated by supporting the shoe 1 through the elastic body. This is because the pulling height can be freely set by adjusting the elastic constant of the elastic body.

Next, the device of the present invention is a seam pulling device which is arranged between the forming roll group 8 and the squeeze roll 22 as shown in FIG. 1 and which can be preferably used for carrying out the method of the present invention. For example, as shown in FIG.
The shoe 1 slidably contacting the inner surfaces of both edge portions 23a, 23b and passing between the both edge portions 23a, 23b and supported on the outer surface side of the open pipe 23, and the shoe 1 supported by the supported portion of the shoe 1 are opened. tube
23 A seam pulling device 6 having an elastic supporting means 7 exerting an elastic pulling force in the direction of arrow 3 from the outer surface side. The shoe 1 is not particularly limited in its form, but in this example, a foot portion 1a slidingly contacting the inner surface of the open tube 23, an ankle portion 1b inserted between the end surfaces of both edge portions 23a, 23b, The structure is made of a sequential connecting body with the base leg portion 1c forming the supported portion. This is a plastic,
It is preferably made of ceramics or the like.

The elastic supporting means 7 is formed by suspending and supporting the elastic body 4 as described above by a supporting frame 5 arranged at an appropriate position vertically above both edge portions 23a, 23b. The free end of the elastic body 4 is connected to the shoe 1 base leg portion 1c so that the elastic body 4 contracts freely when the shoe 1 foot portion 1a is in a working (sliding contact) state. By setting the height position of the end), it is possible to constantly apply an attractive force in the arrow 3 direction to the shoe 1. In addition, the shoe 1 is attached to the support frame 5.
It is preferable to dispose a shoe guide (not shown) for restraining an extra movement (a movement other than the vertical movement).

[0017]

[Example] Wall thickness from a strip steel material having a composition equivalent to JIS G3445
When manufacturing an electric resistance welded steel pipe of 1.0 mm x 100 mm outer diameter, the seam pulling up device 6 of Fig. 2 was used, the elastic body 4 was made of spring, the shoe was made of plastic, and the pulling height of both edges of the open pipe was set. The example of the present invention in which both edges of the open pipe were operated while the product pipe radius was set to a distance of +2.0 mm vertically above the center of the pass line, and the operation was performed without the pulling. Comparing the rate of occurrence of misalignment defects in the product seam with the conventional example, 32% of the conventional example
On the other hand, in the example of the present invention, it was 0.5%, which was a significant improvement effect.

[0018]

According to the present invention, there is an excellent effect that a welded pipe can be manufactured while stably and effectively preventing the generation of an edge wave before welding of an open pipe edge portion.

[Brief description of drawings]

FIG. 1 is a schematic side view showing an embodiment of a method of the present invention.

FIG. 2 is a schematic front sectional view showing an embodiment of the device of the present invention.

FIG. 3 is a schematic view showing an example of a welded pipe manufacturing line ((a): a partial side view of the line, (b): an AA arrow view of (a)).

FIG. 4 is an explanatory diagram showing the occurrence of edge stretch due to forming of a steel strip into an open pipe.

FIG. 5 is an explanatory diagram showing a gap G caused by an edge wave.

FIG. 6 is a schematic view showing an example of a conventional inner seam guide roll device ((a): side view, (b): BB arrow view of (a)).

[Explanation of symbols]

1 shoe 1a foot 1b ankle 1c Base leg 2 arrow (passing direction) 3 arrows (pulling direction) 4 Elastic body (spring etc.) 5 support frame 6 Seam lifting device 7 Elastic support means 8 forming rolls 11 Inner seam guide roll device 12a, 12b Push-up roll 14a, 14b lifting means 15 Supporting platform 16 bottom roll 21 fin roll 22 Squeeze Roll 23 open pipe 23a, 23b, edge of open pipe 24 seam guide rolls 25 strip steel 25a, 25b Edge of steel strip 25c band width center 30 Welded pipe (ERW steel pipe)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takahiro Matsuo             1-1 Kawasaki-cho, Handa-shi, Aichi Made in Kawasaki             Chita Works of Iron Co., Ltd. F-term (reference) 4E028 CA02 CA13 CB02 CB06

Claims (2)

[Claims] 1. A method for producing a welded pipe, wherein strip steel is gradually width-bent formed by a forming roll group to form an open pipe, and both edge portions of the open pipe are abutted by squeeze rolls and welded together. Between the squeeze roll and the squeeze roll, the both edge portions are pulled up via a shoe that is slidably contacted with the inner surfaces of the both edge portions between the both edge portions. . 2. A seam pulling device arranged between a group of forming rolls formed by gradually bending a strip steel into an open pipe and a squeeze roll for welding while abutting both edges of the open pipe. And a shoe which slidably contacts the inner surfaces of the both edge portions and is supported on the outer surface side of the open pipe by passing between the both edge portions, and an elastic portion from the outer surface side of the open pipe to the supported portion of the shoe. A seam pulling device having an elastic supporting means exerting a dynamic pulling force.