JP6928947B2 - Steel pipe manufacturing equipment and steel pipe manufacturing method - Google Patents

Description

The present invention relates to a steel pipe manufacturing facility and a method for manufacturing a steel pipe. It relates to equipment and a manufacturing method for manufacturing a tubular steel pipe.

Conventionally, in this type of steel pipe manufacturing equipment, the steel sheet as the raw material is continuously discharged and passed through the breakdown roll, the cluster roll and the fin pass roll in order so that the edge portions on both sides in the width direction of the steel sheet face each other. A tubular steel pipe is manufactured by curved molding and welding the opposing edges.

For example, in the steel pipe manufacturing facility shown in Patent Document 1, when the end of a steel strip continuously formed into a cylindrical shape by a forming roll is high-frequency welded to produce an electrosewn steel pipe, a circular pipe is used as the final fin pass roll. A three-way roll is used in which the circumferential direction is divided into three and each roll is responsible for forming one-third of the circumferential direction. After forming the steel sheet into a cylindrical shape, both ends of the steel sheet in the width direction are butted against each other. It is intended to manufacture an electric resistance welded pipe in which convexity is not locally generated during high-frequency welding and the butt accuracy of both ends in the width direction of the steel sheet is improved.

Japanese Unexamined Patent Publication No. 2003-236611

However, in the steel pipe manufacturing equipment shown in Patent Document 1, immediately after the tip edge portion of the steel sheet that has passed through the finpass roll (the front edge portion of the steel sheet to be conveyed) is introduced into the high frequency resistance welding machine (electric resistance welding apparatus). Since the welding current applied to the introduced steel sheet is small, the amount of welding heat input to the steel sheet is small, and the surfaces where the end faces on both sides in the width direction of the steel sheet are butted against each other are not sufficiently melted. Therefore, a cold contact defect with insufficient welding strength occurs at the tip edge portion of the steel sheet.

Further, when a steel pipe is manufactured by cutting a steel plate to a predetermined length, the steel plate is subjected to high-frequency resistance welding because there is a distance between the seam guide provided in front of the squeeze roll and the welding point of the end face of the steel plate. When introduced into a machine (electric resistance welding device), the seam guide supports the rearmost edge of the steel sheet in the longitudinal direction (the rear edge of the steel sheet to be conveyed), and the edges of the steel sheet on both sides in the width direction. It is not possible to maintain the angle (convergence angle) formed by the locus of the portion at a predetermined angle that is optimal for welding. In addition, since there is a distance between the contact tip of the high-frequency resistance welder and the welding point on the end face of the steel sheet, a welding current is applied to the rearmost edge of the steel sheet when the rearmost edge of the steel sheet passes through the contact tip. It will not be energized. For this reason, welding defects occur at the rearmost edge of the steel sheet (the rear edge of the steel sheet to be conveyed).
As described above, since a defect in electric resistance welding occurs at the edge portion of the steel sheet, there is a problem that a loss occurs at the edge portion in the longitudinal direction of the manufactured steel pipe.

Therefore, an object of the present invention is to provide a steel pipe manufacturing facility and a steel pipe manufacturing method that reduce the loss of the edge portion of the steel pipe due to a defect in electric resistance welding.

The problem to be solved by the present invention has been described above, and next, the means for solving this problem will be described.

That is, the steel pipe manufacturing facility of the present invention manufactures a circular tubular steel pipe by abutting the end faces on both sides in the width direction of the steel sheet while bending the steel pipe so that the end faces on both sides in the width direction face each other. The equipment includes an electric resistance welding device that performs electric resistance welding on a surface in which both end faces of both sides in the width direction of the steel sheet are abutted along the longitudinal direction of the steel sheet. Energization heating is started via a start tab that can energize a welding current provided at a welding point on the end face of the steel sheet, which is one end edge of the steel sheet in the longitudinal direction, and is started from one side of the steel sheet in the longitudinal direction. Electrical resistance welding is performed on the steel sheet toward the other side, and the start tab cuts a part of a steel pipe having the same diameter and thickness as the circular tubular steel pipe in which the end faces on both sides in the width direction of the steel sheet are in contact with each other. It is composed of a curved plate-shaped member formed by lacking .
In the above configuration, the electric resistance welding apparatus starts welding via a start tab provided on one end edge of the steel sheet in the longitudinal direction.

Further, the steel pipe manufacturing equipment of the present invention is the above-mentioned steel pipe manufacturing equipment, and the electric resistance welding apparatus is energized and heated to an end tab capable of energizing a welding current provided at the other end edge of the steel sheet in the longitudinal direction. Is to do.
In the above configuration, the electric resistance welding device, the welding to end tabs provided in the longitudinal direction through the start tab provided at the end edge of one side to start welding, the other longitudinal side edge of the steel plate of the steel plate conduct.

Further, the method for manufacturing a steel pipe of the present invention is a steel pipe for manufacturing a circular tubular steel pipe by abutting the end faces on both sides in the width direction of the steel sheet while bending the steel pipe so that the end faces on both sides in the width direction face each other. of a manufacturing method, the welding point of a longitudinal edge of one side of the curving the steel plate end faces of the steel sheet, a circle between the end faces of both sides in the width direction of the steel sheet is in contact It is composed of a curved plate-shaped member formed by cutting out a part of a steel pipe having the same diameter and thickness as a tubular steel pipe , provided with a start tab capable of energizing a welding current, and the length of the curved steel plate. An end tab capable of energizing a welding current is provided at the other end edge in the direction, and energization heating is started via the start tab provided at the one end edge in the longitudinal direction of the steel sheet to start energization heating in the longitudinal direction of the steel sheet. From one side to the other, electrical resistance welding is performed on the surfaces where the end faces on both sides in the width direction of the steel sheet are butted against each other, and energization heating is performed up to the end tab provided on the other end edge in the longitudinal direction of the steel sheet. Is a way to do.
In the above method, welding is started via a start tab provided on one end edge of the steel sheet in the longitudinal direction, and welding is performed up to an end tab provided on the other end edge of the steel sheet in the longitudinal direction.

According to the steel pipe manufacturing equipment and the steel pipe manufacturing method of the present invention, electric resistance welding can be appropriately performed at the longitudinal edge portion of the steel sheet, so that electrical resistance welding is defective at the longitudinal edge portion of the steel sheet. Is unlikely to occur. Therefore, it is possible to reduce the loss of the end edge portion of the manufactured steel pipe.

It is a perspective view which shows the steel pipe manufacturing equipment which concerns on embodiment of this invention. It is a perspective view at the time of introducing a steel plate into a high frequency resistance welding machine in the steel pipe manufacturing equipment which concerns on embodiment of this invention. It is a top view when the steel plate is introduced into the high frequency resistance welding machine in the steel pipe manufacturing equipment which concerns on embodiment of this invention. (A) is a plan view of the steel plate to which the end tab is attached, and (b) is a side view of the rear side of the steel plate to which the end tab is attached.

Hereinafter, the steel pipe manufacturing equipment 10 according to the embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the steel pipe manufacturing facility 10 is curved so that the end faces 91 (FIG. 3) on both sides in the width direction of the steel plate 90 (the direction horizontally orthogonal to the transport direction H of the steel plate 90) face each other. Then, the end faces 91 on both sides are butted against each other and welded to form a circular tubular steel pipe 93.

In the steel pipe manufacturing facility 10, when manufacturing a circular tubular steel pipe 93, a steel plate 90 having a predetermined plate thickness corresponding to the steel pipe 93 is cut to a predetermined length and prepared. The steel plate 90 is conveyed in the conveying direction H by a conveying device (not shown). The steel plate 90 is formed into a gentle R shape by the preform device 11 so that the end faces 91 on both sides in the width direction face each other, and then gradually arcuate by the breakdown device 12 composed of a plurality of breakdown rolls 12A. It is curved and molded.

The arc-shaped curved steel plate 90 is formed by bending inward a pair of vertical plate portions on the upper portion of the cluster device 13 composed of a plurality of cluster rolls 13A. Then, the finpass device 14 composed of the plurality of finpass rolls 14A gradually forms a circular tubular shape, and the circular tubular steel pipe 93 in which the end faces 91 on both sides in the width direction are in contact with each other is press-formed. The circular tubular steel pipe 93 is introduced into a high-frequency resistance welding machine 20 (an example of an "electric resistance welding device"), and after welding by a melting method by heating is performed, an outer surface beat is cut by the cutting device 15 and a seam welded portion is formed. A circular tubular steel pipe 93 having the above is manufactured.

As shown in FIGS. 1 to 3, in the steel pipe manufacturing facility 10, the steel plate 90 formed into a circular tube in the finpass device 14 is introduced into the high-frequency resistance welding machine 20 arranged on the downstream side of the finpass device 14. .. Here, in the steel plate 90 formed into a circular tubular shape, the angle formed by the locus of the end face 91 around the welding point P of the end face 91 (hereinafter, referred to as “convergence angle θ”) is set to a predetermined angle suitable for welding. It is conveyed to the squeeze roll 30 in a held state. Then, the steel plate 90 formed into a circular tubular shape temporarily stops when the front end edge (an example of "one end edge in the longitudinal direction of the steel plate") portion in the transport direction H is transported to the squeeze roll 30. The start tab 40 (an example of the "energizing member") is attached to the front edge of the statically heated state.

As shown in FIG. 2, the start tab 40 is a curved plate-shaped member made of a material capable of applying a welding current energized from the high-frequency resistance welding machine 20. The start tab 40 is formed by a cutout portion obtained by cutting out a part of a steel pipe 41 having substantially the same diameter and thickness as the front edge of the steel plate 90 formed into a circular tubular shape by the finpass device 14. The start tab 40 is formed to have the same thickness as the steel plate 90. The edge of the start tab 40 on the side opposite to the side cut out from the steel pipe 41 is grooved, and the edge is welded to the front edge of the steel plate 90.

When the start tab 40 is attached to the front edge of the steel plate 90, a welding current is applied to the end face 91 of the steel plate 90 facing a substantially V shape and converging via the contact tip 21 of the high frequency resistance welding machine 20. Here, since the welding current applied to the steel plate 90 is small at the initial stage of energization by the contact tip 21, the welding current is applied in advance through the start tab 40. As a result, when the end face 91 of the steel plate 90 is sufficiently energized and heated via the contact tip 21, the surface where the end faces 91 of the steel plate 90 are butted against each other can be pressed by the squeeze roll 30, and the front end of the steel plate 90 can be pressed. Welding in the part can be performed well.

The steel plate 90 introduced into the high-frequency resistance welding machine 20 is energized and heated along its longitudinal direction to melt the end face 91 that faces a substantially V shape and converges. Then, the steel plate 90 has a pair of squeeze at the welding point P of the end face 91 while the convergence angle θ is held at a predetermined angle optimal for welding by a seam guide (not shown) provided in front of the squeeze roll 30. By being pressed by the roll 30, the end faces 91 are butt-butted and pressure-welded (butt-welded).

The steel plate 90 introduced into the high-frequency resistance welding machine 20 is welded toward the rear edge of the transport direction H (an example of "an example of" the other edge in the longitudinal direction of the steel sheet "). Then, the steel plate 90 is welded to the end tab 50 (an example of the "energizing member") attached to the rear edge of the transport direction H.

As shown in FIGS. 2 to 4, the end tab 50 is a long plate-shaped member made of a material capable of carrying a welding current energized by the high-frequency resistance welding machine 20. The end tab 50 is formed of a steel plate having the same thickness as the steel plate 90. The end tab 50 has a rigidity that can be supported by a seam guide (not shown) provided in front of the squeeze roll 30. When the end tab 50 is supported by the seam guide behind the steel plate 90, the end tab 50 has a longitudinal length (so that the convergence angle θ on the rear side of the steel plate 90 is held at a predetermined angle optimal for welding. The length of the steel plate 90 in the transport direction H) is set to a predetermined length. That is, the length of the end tab 50 in the longitudinal direction is set according to the distance between the welding point P of the end surface 91 of the steel plate 90 and the seam guide, and when the rear end portion of the steel plate 90 is welded, the end tab 50 Is configured to be supported by the seam guide. Further, the end tab 50 has a length in the longitudinal direction (conveyance of the steel plate 90) so that a welding current is applied from the contact tip 21 of the high-frequency resistance welding machine 20 when the rear end portion of the steel plate 90 is welded. The length in the direction H) is set to a predetermined length. That is, the length of the end tab 50 in the longitudinal direction is set according to the distance between the welding point P of the end face 91 of the steel plate 90 and the contact tip 21, and when the rear end of the steel plate 90 is welded, the end tab 50 Is configured to come into contact with the contact tip 21.

The end tab 50 is attached to the rear edge of the steel sheet 90 before the steel sheet 90 is processed by the preform device 11. That is, the end tab 50 is attached to the rear edge of the steel plate 90 in advance before the end faces 91 of the steel plate 90 are welded to each other by the high frequency resistance welding machine 20. As shown in FIG. 4B, one edge of the end tab 50 in the longitudinal direction is grooved, and the end tab 50 is welded to the rear edge of the steel sheet 90 by welding 51. The end tab 50 is attached to both left and right edge edges on the rear side of the steel plate 90 so that one end surface (outside) in the width direction thereof is flush with the end surface in the width direction of the steel plate 90.

As described above, in the steel pipe manufacturing facility 10, the end tab 50 is provided at the rear edge of the steel sheet 90, and the welding current is applied to the end tab 50 to optimize the convergence angle θ on the rear side of the steel sheet 90 for welding. The rear end of the steel sheet 90 can be welded while being held at a predetermined angle, and when welding the rear end of the steel sheet 90, a welding current is applied to the rear end of the steel sheet 90 via the end tab 50. Can be energized. Therefore, the surfaces where the rear end faces 91 of the steel plate 90 are butted against each other are appropriately welded, and the welding at the rear end portion of the steel plate 90 can be satisfactorily performed.

The tubular steel plate 90 formed by welding with a high-frequency resistance welding machine 20 becomes a steel pipe 93 by cutting off the start tab 40 and the end tab 50 after the welding is completed.

As described above, according to the above configuration, electrical resistance welding can be appropriately performed at the longitudinal edge portions (front end portion and rear end portion) of the steel sheet 90, so that the longitudinal edge portion of the steel sheet 90 can be appropriately performed. Defective electric resistance welding is unlikely to occur. Therefore, it is possible to reduce the loss of the edge portion in the longitudinal direction of the manufactured steel pipe 93.

In the present embodiment, the steel plate 90 is provided with the start tab 40 and the end tab 50 as energizing members, but the present invention is not limited to this, and either the start tab 40 or the end tab 50 is provided. It doesn't matter.

In the present embodiment, the steel pipe 93 is manufactured using the steel plate 90 cut to a predetermined length, but the present invention is not limited to this, and the steel pipe is manufactured using the coiled strip steel plate. It doesn't matter. In this case, the start tab 40 is attached to the front edge of the steel strip.

In the present embodiment, the steel pipe manufacturing facility 10 is a facility for manufacturing a circular tubular steel pipe 93, but the present invention is not limited to this, and an facility for manufacturing a square steel pipe may be used.

10 Steel pipe manufacturing equipment 20 High-frequency resistance welding machine (electric resistance welding equipment)
40 Start tab (energized member)
50 End tab (energized member)
90 Steel plate 91 End face 93 Steel pipe

Claims (3)

A steel pipe manufacturing facility that manufactures a circular tubular steel pipe by abutting the end faces on both sides of the steel sheet in the width direction while bending and forming so that the end faces on both sides in the width direction of the steel sheet face each other.
An electric resistance welding device for performing electric resistance welding on a surface in which both end faces of both sides in the width direction of the steel sheet are abutted along the longitudinal direction of the steel sheet is provided.
The electric resistance welding device is
Energization heating is started via a start tab capable of energizing a welding current provided at a welding point on the end face of the steel sheet at one end edge in the longitudinal direction of the steel sheet.
Electrical resistance welding is performed on the steel sheet from one side to the other side in the longitudinal direction of the steel sheet.
The start tab is composed of a curved plate-shaped member formed by cutting out a part of a steel pipe having the same diameter and thickness as a circular tubular steel pipe in which both end faces in the width direction of the steel plate are abutted. steel pipe manufacturing facility, characterized in that that. The electric resistance welding device is
The steel pipe manufacturing facility according to claim 1, wherein the welding current provided at the other end edge of the steel sheet in the longitudinal direction is energized and heated to an end tab capable of energizing the welding current. A method for manufacturing a steel pipe, which manufactures a circular tubular steel pipe by abutting the end faces on both sides in the width direction of the steel sheet while bending the steel pipe so that the end faces on both sides in the width direction face each other.
It has the same diameter as a circular tubular steel pipe, which is one end edge of the curved steel sheet in the longitudinal direction and in which the welding points of the end faces of the steel sheet are in contact with both end faces in the width direction of the steel sheet. It is composed of a curved plate-shaped member formed by cutting out a part of a steel pipe of the same thickness, and is provided with a start tab capable of energizing a welding current.
An end tab capable of energizing a welding current is provided at the other end edge of the curved steel sheet in the longitudinal direction.
Energization heating is started through the start tab provided on one end edge of the steel sheet in the longitudinal direction.
From one side in the longitudinal direction of the steel sheet to the other side, electric resistance welding is performed on the surfaces where the end faces on both sides in the width direction of the steel sheet are butted against each other.
A method for manufacturing a steel pipe, which comprises energizing and heating up to the end tab provided on the other end edge of the steel sheet in the longitudinal direction.

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