JP2003251406A - Method and equipment array for fabricating welded tube - 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 into a tube. <P>SOLUTION: In the method for fabricating the welded tube by which band steel 25 is made into the open tube 23 by forming it by gradually bending the width by a forming roll group 8 and welding is performed while butting both edge parts 23a, 23b of the open tube 23 with squeeze rolls 22, center waves are imparted to a material to be formed by pressing only the center part 25c in the width of the band with a center pushing roll 1 on the upstream side of the squeeze roll preferably on the inlet side of the forming roll group. <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 method of manufacturing a welded pipe and a system of equipment, and more particularly, to a round welded pipe by welding both edge portions of an open pipe formed into a substantially round shape by a roll forming method. A method and a train of equipment 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, 25b of the steel strip 25 or both edge portions 23a, 23b of the open pipe 23 are in a temporarily stretched edge stretch state.

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 to provide an equipment line.

[0009]

According to the present invention, the center of the band width of the material to be molded (corresponding to the open tube bottom) is pressed by a roll on the upstream side of the molding line to positively cause belly expansion. The above-mentioned object is achieved. That is,
The present invention is a method for manufacturing a welded pipe in which a strip steel is gradually width-bent formed by a forming roll group to form an open pipe, and both edges of the open pipe are welded while abutting each other with a squeeze roll. On the side, preferably on the entry side of the group of forming rolls, only the central portion of the band width is pressed by the rolls to impart belly stretch to the material to be formed.

Further, according to the present invention, an uncoiler for discharging a strip steel, a strip splicing welder for welding a trailing end of a preceding strip to a trailing strip of the strip, a looper for storing and delivering the strip, and a strip strip gradually. Welded pipe having a series of a series of forming rolls formed by width-bending forming into an open pipe, an edge heating device for heating both edge parts of the open pipe, and a squeeze roll for abutting both end portions of the open pipe. In the manufacturing equipment row, between the band splicing welder and the squeeze roll, preferably between the looper and the forming roll group, a central push roll that presses only the central portion of the strip width is arranged. This is a welding pipe manufacturing equipment line.

[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 a welding method, a high energy beam welding method such as laser, a high frequency electric resistance welding method, a TIG welding method, a MIG welding method, a MAG welding method, and the like, a welding method combining these methods, and a solid phase pressure welding method are also available. It can be preferably used.

According to the method of the present invention, on the upstream side of the squeeze roll, only the central portion of the band width (corresponding to the bottom of the open pipe) is pressed by the roll in either one of the upper and lower directions to give the material to be stretched. Therefore, L1C is replaced by L1 in FIG.
Edge stretch can be mitigated as close as possible to E, thus preventing edge waves. A roll that presses only the central portion of the band width (corresponding to the open pipe bottom) or the open pipe bottom is referred to as "central push roll" in the present invention. Since this central push roll can be placed outside the open pipe, there is a concern about the problem of space compatibility with other pipe interior entry devices and the positional displacement due to interference with them, which occurred in the conventional technology [2]. There is no qualitative problem.

The shape step of the material to be stretched is
It may be either a strip steel stage or an open pipe stage,
Pressing the open pipe with the central push roll tends to disturb the shape in the circumferential direction, and the disturbance may make the welding unstable, but since it does not occur in the strip steel, for example, in FIG. As shown, it is preferable to press the strip steel 25 with the central push roll 1. In this example, the steel strip 25 threaded in the direction of arrow 2 is pressed by the central push roll 1 in the direction of arrow 3 (upward), but it may be pressed downward. In any case, in the threading section from the entrance side to the exit side of the central push roll 1, the threading locus at one point in the central portion 25c of the belt width is 1 at each of the edge portions 25a and 25b at the same position in the longitudinal direction of the belt. Since it becomes longer than the passage path of the point, and the material to be molded is in a state of belly stretch, this belly stretch is offset by the uneven stretch of both edges that is likely to occur in the gradual width bending forming by the forming roll group in the next process. Yes (Fig. 4
Therefore, the edge stretch is reduced.

In FIG. 1, reference numeral 10 denotes a pinch roll equivalent means having a function of restraining extra movement of the strip steel 25 on the inlet side and the outlet side of the central push roll 1, and the pinch roll equivalent means 10 is The form is not particularly limited as long as it has such a function, and it is an existing one in the pipe making line (for example, on the downstream side, the first-stage breakdown roll of the forming roll group, etc.)
Can also be combined. Further, in order to easily give the material to be stretched, it is necessary to apply tension in the line direction (longitudinal direction) to the material to be pressed by the central push roll, in the direction perpendicular to the line direction. It is effective to apply tension and further to restrain the edge portions 25a and 25b of the material to be molded.

Further, the pressing amount η by the central pressing roll 1 (see FIG.
(b)) may be preset to the optimum value obtained in advance by experiment, but the degree of edge wave generation is sensed on the downstream squeeze roll entrance side, and feedback is provided so that the sensing data falls within the specified allowable range. Controlling is preferable because the edge wave can be prevented more effectively. Next, the equipment sequence of the present invention will be described. This is a production equipment sequence of welded pipes suitable for carrying out the method of the present invention. For example, as shown in FIG. An uncoiler 5 for discharging the steel 25, a band splicing welder 6 for welding the trailing end of the preceding material to the tail end of the band 25, a looper 7 for storing and delivering the band 25, and a gradual width bending of the band 25 Forming roll group 8 forming an open pipe 23, an edge heating device (induction heating coil) 9 for heating both edge portions 23a and 23b of the open pipe 23, and an open pipe
23 having a squeeze roll 22 that abuts the end faces of both edge portions in series, and between the band splicing welder 6 and the squeeze roll 22, preferably as shown between the looper 7 and the forming roll group 8. The central push roll 1 according to the method of the present invention is arranged in between. Here, of the forming roll group 8,
Only the first-stage breakdown roll 18 and the last-stage fin pass roll 21 are shown, and a plurality of stages of cage rolls or CBR (Chance Free Bulg) are arranged in series between them.
e Roll Forming Process) and the like are omitted.

In the example of FIG. 2, the looper outlet pinch roll 17 and the breakdown roll 18 are also used as the pinch roll equivalent means 10 of FIG. In addition, the pressing amount of the central push roll 1 (η in FIG. 1 (b)) is the edge wave height (: edge) calculated from the distance measured by the sensor (laser distance meter) 4 on the open end of the fin pass roll 21. The pressure is controlled by a feedback system that automatically operates the pressure actuator (air cylinder) 1A so that the amplitude of the wave is within the allowable range.

With such an equipment row, the strip steel is continuously roll-formed into an open pipe, and the edge portion of the open pipe is effectively and stably prevented from being generated, and the edge portion is effectively prevented. The end faces can be heated, abutted, and pressure-welded, and a welded pipe having a good shape with no misalignment (step) at the product seam can be manufactured.

[0018]

[Example] Wall thickness from a strip steel material having a composition equivalent to JIS G3445
In manufacturing an electric resistance welded steel pipe having an outer diameter of 1.0 mm and an outer diameter of 100 mm, the present invention example in which the allowable range of the edge wave height in the feedback control was set to 0.2 mm using the equipment row of FIG.
When the ratio of the number of occurrence of misalignment defects in the product seam portion is compared with the conventional example in which operation is performed using the equipment row in which the central push roll 1 is removed from FIG. 2, 35% of the conventional example is compared with the conventional example. Two
%, And a significant improvement effect was obtained.

[0019]

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 an explanatory view ((a): side view, (b): CC arrow view of (a)) showing an embodiment of the method of the present invention.

FIG. 2 is a schematic side view showing an embodiment of an equipment row 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 Oshi roll 1A push actuator (air cylinder) 2 Corresponding arrow direction 3 Pressing direction equivalent arrow 4 sensors (laser rangefinder) 5 Uncoiler 6 band joint welder 7 Looper 8 forming rolls 9 Edge heating device (induction heating coil) 10 pinch roll equivalent 11 Inner seam guide roll device 12a, 12b Push-up roll 14a, 14b lifting means 15 Supporting platform 16 bottom roll 17 Looper exit pinch roll 18 breakdown rolls 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)

Claims (4)

[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 to each other. A method for manufacturing a welded pipe, characterized in that, on the upstream side, only the central portion of the band width is pressed by a roll to impart belly stretch to the material to be formed. 2. The method for producing a welded pipe according to claim 1, wherein the belly elongation is provided on the entry side of the forming roll group. 3. An uncoiler for discharging strip steel, a band splicing welder for welding a trailing end of a preceding strip to a trailing strip of the strip, a looper for storing and delivering the strip, and a step of gradually bending the strip. Welded pipe manufacturing equipment having a series of a series of a series of forming rolls that form an open pipe, an edge heating device that heats both edges of the open pipe, and a squeeze roll that abuts the end faces of both edges of the open pipe. In the above, in the welding pipe manufacturing equipment row, a central push roll that presses only the central portion of the strip width is arranged between the band joint welder and the squeeze roll. 4. The welding pipe manufacturing equipment row according to claim 3, wherein the central push roll is arranged between the looper and the forming roll group.