JP2019177395A - Bending method and device of end of steel plate, manufacturing method of steel pipe, and equipment - Google Patents

Abstract

An end bending shape with less variation in a longitudinal direction of a steel sheet is obtained. Kind Code: A1 A steel sheet is intermittently conveyed by a conveying mechanism, and a pair of dies are used to bend a plurality of width ends Sc and Sd of the steel sheet a plurality of times to form the width of the steel sheet. This is an end bending method for a steel plate in which bending ends are formed on the direction ends Sc and Sd over the entire length. At the time of bending the ends Sc and Sd in the width direction of the steel sheet S, the plurality of mold moving means are controlled so that the moving amounts of the plurality of mold moving means are substantially equal. [Selection diagram] FIG.

Description

  The present invention relates to an end bending method and apparatus for bending a steel sheet in the width direction end portion in a plurality of times in the plate length direction. Further, the present invention is a method of manufacturing a steel pipe by forming a steel plate subjected to end bending into a cylindrical shape, butting the end portions in the width direction, and joining the end portions in the width direction of the abutted steel plates by welding. And related to equipment.

  For the production of large-diameter steel pipes used for line pipes, etc., after forming a steel sheet having a predetermined length, width and thickness into a cylindrical shape with the longitudinal direction of the steel sheet as the pipe axis direction by pressing, A method is used in which the end portions in the width direction are butt-joined. In order to facilitate forming into a cylindrical shape and obtain an appropriate tube shape, end bending forming (C press) is performed to give a predetermined curvature to the widthwise end of the steel plate prior to forming into a cylindrical shape.

  In this end bending, a steel plate is placed between a lower die and an upper die having a curvature corresponding to the pipe diameter, and the lower die is pushed up by a hydraulic cylinder so that the end in the width direction of the steel plate is the upper die. However, since the steel plate is longer than the effective length of the mold, the steel plate cannot be processed over the entire length with a single press. Therefore, a method is adopted in which end bending is performed over the entire length by bending the steel sheet to the end in the width direction of the steel sheet a plurality of times (for example, 3 to 4 times) while intermittently feeding the steel sheet in the longitudinal direction. .

  Patent Documents 1 to 3 disclose a method for obtaining a good shape at a butt portion. In patent document 1, the feed length b is prescribed | regulated according to the thickness and intensity | strength of a steel plate. In Patent Document 2, the length Lc of the bending region is defined according to the thickness and strength of the steel plate. In Patent Document 3, the radius R1 of the upper die, the horizontal distance u from the center of curvature of the upper die to the end of the steel plate, and the pressing force w are defined according to the thickness and strength of the steel plate. Patent Document 4 proposes a method for manufacturing a steel pipe with little variation in the shape of the butt portion based on the strength information of the steel sheet.

  Further, in Patent Document 5, a bending tool member including a force generating element and a through bolt is disposed on a support body extending across the longitudinal axis of the steel plate so as to be movable and fixable. There have been proposals for presses that sometimes prevent differences between the edges.

  Furthermore, Patent Document 6 proposes a method of continuously performing end bending.

JP-A-8-294727 JP-A-10-2111520 JP 2008-119710 A JP 2009-6358 A JP 2008-161941 A JP-A-7-32049

  However, all of Patent Documents 1 to 4 are for the purpose of optimizing the shape of a cross section with a steel plate, and the variation of the end bending shape in the longitudinal direction of the steel plate has not been studied. Also in patent document 5, the fluctuation | variation in the longitudinal direction of the shape of both edge parts is not examined. In particular, in a thick-walled and high-strength steel sheet, the end bending shape may not be uniform in the longitudinal direction of the steel sheet, leading to poor welding of the butt portion and poor butt portion shape of the product steel pipe. Further, in the method described in Patent Document 6, it is not certain that the front end portion without the steel plate in the front and the tail end portion without the steel plate in the rear have the same shape as the central portion in the longitudinal direction.

  An object of the present invention is to eliminate the above-mentioned problems of the prior art and to obtain an end bending shape with little fluctuation in the longitudinal direction of the steel sheet.

  The inventors investigated the variation of the end bending shape in the plate length direction and elucidated the cause of the variation, leading to the present invention. The first aspect includes a pair of molds arranged corresponding to the widthwise ends of the steel sheet, a plurality of mold moving means for relatively moving the pair of molds in the proximity direction, and a steel sheet. Using a steel plate end bending device that transports the direction along the longitudinal direction as a transport direction, while the steel plate is intermittently transported by the transport mechanism and the pair of molds are relatively moved in the proximity direction. Is a method of bending an end of a steel sheet by bending the width direction end of the steel sheet a plurality of times, thereby bending the entire length of the steel sheet in the width direction. In the end bending method of the steel sheet, the amount of movement of the plurality of mold moving means is controlled so that the bending angle of the steel sheet becomes substantially equal in the longitudinal direction of the steel sheet during bending of the end portion.

  A 2nd aspect is a pair of metal mold | die arrange | positioned corresponding to the width direction edge part of a steel plate, the some metal mold moving means to which the said metal mold | die relatively moves to a near direction, and a steel plate A pair of molds relative to each other in the proximity direction while intermittently transporting the steel sheet by the transport mechanism. Is a method of bending an end of a steel sheet by bending the end part in the width direction of the steel sheet a plurality of times, thereby bending the entire length of the end part in the width direction of the steel sheet. This is a steel sheet end bending method of controlling the plurality of mold moving means so that the movement amounts of the plurality of mold moving means become substantially equal during bending of the part.

  According to a third aspect, a pair of molds arranged corresponding to the widthwise ends of the steel sheet, a plurality of mold moving means for relatively moving the pair of molds in the proximity direction, A pair of molds relative to each other in the proximity direction while intermittently transporting the steel sheet by the transport mechanism. Is a method of bending an end of a steel sheet by bending the end part in the width direction of the steel sheet a plurality of times, thereby bending the entire length of the end part in the width direction of the steel sheet. This is a steel sheet end bending method in which the plurality of mold moving means are controlled so that the distance between the pair of molds becomes substantially equal in the transport direction during bending of the part.

  According to a fourth aspect, in any one of the first to third aspects, the one mold is a curved surface provided adjacent to the upstream side and the downstream side in the transport direction of the flat portion, respectively. The flat portion and the relief portion are end bending methods of steel plates that are connected with a common tangent line.

  In a fifth aspect, in any one of the first to fourth aspects, in the first pass of bending to the end in the width direction of the steel plate, the front end of the steel plate in the transport direction is changed to the flat portion. It is the end bending method of the steel plate made into the position united with the front end.

  In a sixth aspect, in any one of the first to fifth aspects, in the last pass of bending to the width direction end of the steel plate, the tail end of the steel plate in the transport direction is the flat portion. It is the edge bending method of the steel plate made into the position match | combined with the back end.

  In the seventh aspect, a pair of molds arranged corresponding to the widthwise ends of the steel sheet, mold moving means for relatively moving the pair of molds in the proximity direction, and the steel sheet in its longitudinal direction A pair of molds are moved relative to each other in the proximity direction while intermittently transporting the steel sheet by the transport mechanism. By bending the width direction end of the steel sheet a plurality of times, the end bending process of the steel sheet to bend the entire length of the width direction end of the steel sheet, and bending at both width direction ends. The steel sheet is formed into a cylindrical shape, and a method of manufacturing a steel pipe includes a cylindrical forming process in which the widthwise ends of the steel sheets are butted together, and a joining process in which the widthwise ends of the butted steel sheets are welded together. The plurality of molds at the time of bending the width direction end of the steel plate As the amount of movement of the motion means are substantially equal, a method for producing a steel pipe for controlling the die moving means of the plurality of.

  In an eighth aspect, a pair of molds arranged corresponding to the widthwise ends of the steel sheet, mold moving means for relatively moving the pair of molds in the proximity direction, and the steel sheet in its longitudinal direction A pair of molds are moved relative to each other in the proximity direction while intermittently transporting the steel sheet by the transport mechanism. By bending the width direction end of the steel sheet a plurality of times, the end bending process of the steel sheet to bend the entire length of the width direction end of the steel sheet, and bending at both width direction ends. The steel sheet is formed into a cylindrical shape, and a method of manufacturing a steel pipe includes a cylindrical forming process in which the widthwise ends of the steel sheets are butted together, and a joining process in which the widthwise ends of the butted steel sheets are welded together. The pair of molds during bending of the width direction end of the steel plate So that the distance is substantially equal in the transport direction, it is a method for producing a steel pipe for controlling the plurality of molds moving means.

  According to a ninth aspect, a pair of molds arranged corresponding to the widthwise ends of the steel sheet, mold moving means for relatively moving the pair of molds in the proximity direction, and the steel sheet in its longitudinal direction A width direction of the steel sheet by moving the pair of molds relatively in the proximity direction while intermittently transporting the steel sheet by the transport mechanism. An end bending device for a steel plate that performs bending over the entire length of the width direction end of the steel plate by bending the end portion a plurality of times. The steel sheet end bending apparatus includes a control unit that controls the plurality of mold moving units so that the movement amounts of the mold moving units are substantially equal.

  In a tenth aspect, a pair of molds arranged corresponding to the widthwise ends of the steel sheet, mold moving means for relatively moving the pair of molds in the proximity direction, and the steel sheet in its longitudinal direction A width direction of the steel sheet by moving the pair of molds relatively in the proximity direction while intermittently transporting the steel sheet by the transport mechanism. An end bending apparatus for a steel plate that performs bending over the entire length of the width direction end of the steel sheet by bending the end portion a plurality of times. The steel plate end bending apparatus includes a control unit that controls the plurality of mold moving units such that the intervals between the molds are substantially equal in the transport direction.

  According to an eleventh aspect, in the ninth or tenth aspect, the one mold is a relief portion formed of curved surfaces provided adjacent to the flat portion on the upstream side and the downstream side in the transport direction, respectively. The flat portion and the relief portion are steel plate end bending devices that are connected with a common tangent line.

  In a twelfth aspect, a pair of molds arranged corresponding to the widthwise ends of the steel sheet, mold moving means for relatively moving the pair of molds in the proximity direction, and the steel sheet in its longitudinal direction The width of the steel plate by moving the pair of molds relatively in the proximity direction while intermittently transporting the steel plate by the transport mechanism A steel plate end bending apparatus that performs bending over the entire length of the width direction end of the steel plate and a steel plate that is bent at both ends in the width direction by cylindrical bending to the direction end. A steel pipe manufacturing facility comprising: a cylindrical forming device that forms the shape and abuts the widthwise ends of the steel plates; and a joining device that welds the widthwise ends of the abutted steel plates; The end bending apparatus is configured such that the plurality of the end bending devices are bent at the end of the steel sheet in the width direction. As the amount of movement of the mold moving means are substantially equal, a production facility of a steel pipe which comprises control means for controlling the die moving means of the plurality of.

  In a thirteenth aspect, a pair of molds arranged corresponding to the widthwise ends of the steel sheet, mold moving means for relatively moving the pair of molds in the proximity direction, and the steel sheet in its longitudinal direction The width of the steel plate by moving the pair of molds relatively in the proximity direction while intermittently transporting the steel plate by the transport mechanism A steel plate end bending apparatus that performs bending over the entire length of the width direction end of the steel plate and a steel plate that is bent at both ends in the width direction by cylindrical bending to the direction end. A steel pipe manufacturing facility comprising: a cylindrical forming device that forms the shape and abuts the widthwise ends of the steel plates; and a joining device that welds the widthwise ends of the abutted steel plates; The end bending apparatus is configured such that the pair of the end portions is bent at the time of bending in the width direction end of the steel plate. As the interval of the die is substantially equal in the transport direction, it is the production facility of a steel pipe with a control means for controlling the plurality of molds moving means.

  According to a fourteenth aspect, in the twelfth or thirteenth aspect, the one mold is a relief portion formed of curved surfaces provided adjacent to the flat portion on the upstream side and the downstream side in the transport direction, respectively. The flat portion and the escape portion are steel pipe manufacturing equipment connected with a common tangent line.

  According to the present invention, by bending the steel plate by controlling the amount of movement of the plurality of mold moving means so that the bending angle of the steel plate is substantially equal in the longitudinal direction of the steel plate during bending of the end portion in the width direction of the steel plate. It is possible to obtain an end bend shape with little fluctuation in the longitudinal direction, and preferably, when a plurality of mold moving means are moved to be substantially equal during bending of the width direction end of the steel sheet. By controlling the means, the inclination of the mold is suppressed, or when bending the end of the steel sheet in the width direction, multiple mold moving means are controlled so that the distance between the pair of molds is substantially equal in the transport direction By doing so, the pressing amount of the mold becomes substantially equal in the conveying direction, so that it is possible to obtain an end bending shape with little fluctuation in the longitudinal direction of the steel plate.

It is a figure explaining the outline of the manufacturing equipment and manufacturing method of a steel pipe of one embodiment of the present invention. It is a top view which shows an example of the steel plate used as the object of an end bending process. It is the schematic which shows the end bending apparatus of the steel plate of one Embodiment of this invention. It is sectional drawing in the width direction which shows the state before the end bending of the press mechanism in the end bending apparatus of the steel plate of FIG. It is sectional drawing in the width direction which shows the state at the time of the end bending of the press mechanism in the end bending apparatus of the steel plate of FIG. It is sectional drawing in the conveyance direction which shows the press mechanism in the conventional end bending apparatus of a steel plate, (a) has shown the state before end bending, (b) has shown the state at the time of end bending. It is a graph which shows the change of the steel plate shape by end bending. (A) shows the relationship between the center of the pressing force, the center of the flat portion, and the center of the bending deformation force when the first end bending process is performed using the conventional steel sheet end bending apparatus shown in FIG. (B) is a diagram schematically showing a state in which the lower mold is inclined due to the relationship between the center of the pressing force, the center of the flat portion, and the center of the bending deformation force. (A) shows the relationship between the center of the pressing force, the center of the flat part, and the center of the bending deformation force when the second end bending process is performed using the conventional steel sheet end bending apparatus shown in FIG. (B) is a diagram schematically showing a state in which the lower mold is inclined due to the relationship between the center of the pressing force, the center of the flat portion, and the center of the bending deformation force. (A) shows the relationship between the center of the pressing force, the center of the flat portion, and the center of the bending deformation force when the end bending process of the final round is performed by using the conventional steel sheet end bending apparatus shown in FIG. (B) is a diagram schematically showing a state in which the lower mold is inclined in the opposite direction due to the relationship between the center of the pressing force, the center of the flat portion, and the center of the bending deformation force. . It is the schematic of the end bending apparatus of the steel plate of one Embodiment of this invention. It is the schematic of the end bending apparatus of the steel plate of other embodiment of this invention. It is sectional drawing along the conveyance direction which shows the lower metal mold | die of the other example which provided the escape part adjacent to the flat part which can be used suitably for this invention. It is a figure explaining peaking. It is a figure explaining an end bending shape and peaking.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same components are denoted by the same reference numerals, and overlapping descriptions are omitted as appropriate. In the specification, “front” or “front” means “downstream side” or “direction from the upstream side to the downstream side” as viewed in the conveying direction of the steel sheet in the end bending apparatus described later, and “rear” or “ “Backward” is the opposite direction.

  FIG. 1 shows an outline of a method and equipment for manufacturing a steel pipe according to an embodiment of the present invention for manufacturing a steel pipe from a steel sheet cut into a predetermined dimension. First, the steel plate S cut to a predetermined size is subjected to groove processing on its side surface by the edge mirror 10 or the edge planar. In the illustrated example, the tab plate St is welded to the front end portion (longitudinal front end portion) Sa and the tail end portion (longitudinal rear end portion) Sb of the steel plate S. However, the tab plate St may not be provided. is there. Next, end bending is performed by the end bending apparatus (C press) 20 according to one embodiment of the present invention (end bending process), and a cylindrical shape is formed by the cylindrical forming apparatus 30 (cylindrical forming process). The cylindrical forming apparatus 30 is not limited to the one formed by the U press 30A for first forming the steel sheet S subjected to end bending forming into a U shape, and then the O press 30B for forming an O shape (cylindrical shape). It is also possible to use a bending press 30C that is provided with a feeding mechanism that feeds S in the width direction and that gradually forms a final cylindrical shape by performing three-point bending while sequentially feeding the steel plates S in the width direction. Next, after joining the width direction edge parts which faced as a result of cylindrical shaping | molding of the steel plate S with the joining apparatus 40 from an outer surface, it welds by the submerged arc welding method etc. from an inner surface and an outer surface, respectively (joining process). Thereafter, the steel pipe S 'is expanded in diameter by the mechanical expander 50, and residual stress is removed and finished to a predetermined outer diameter and dimensions (tube expansion process). In addition, it cannot be overemphasized that other processes, such as washing | cleaning, various inspections, and bead grinding, may be performed between each process or processes.

  A steel plate end bending apparatus 20 and a steel plate end bending method using the same according to an embodiment of the present invention will be described in more detail. FIG. 2 shows an example of the steel sheet S before end bending. The width of the steel sheet S ranges from 1200 mm to 5100 mm, for example, depending on the outer diameter of the product steel pipe. Further, the length of the steel plate is often about 12 m, which is the standard length of a line pipe. A tab plate St is welded to each end in the width direction of the longitudinal end portion Sa and the tail end portion Sb of the steel plate S to be the steel pipe body, but there may be no tab plate St.

  In FIG. 3, the schematic structure of the end bending apparatus 20 of a steel plate is shown. The steel sheet end bending apparatus 20 is configured to bend and deform the left width direction end Sc to a predetermined curvature with the transport mechanism 21 transporting the steel sheet S along the longitudinal direction as the transport direction and the downstream side in the transport direction as the front. The distance between the left and right press mechanisms 22A and 22B is set according to the width of the press mechanism 22A to be bent, the press mechanism 22B to bend and deform the right-side width direction end Sd to a predetermined curvature, and the steel sheet S to be end-bended. And an interval adjusting mechanism (not shown) for adjustment. The transport mechanism 21 includes a plurality of transport rolls 21a disposed before and after the press mechanisms 22A and 22B. Each transport roll 21a is configured such that its roll axis is oriented in a direction orthogonal to the transport direction of the steel sheet S and is rotated at a speed synchronized with each other by a motor and a transmission mechanism (not shown).

  FIG. 4 shows a cross section in the width direction of the pressing mechanism 22A that bends and deforms the left-side width direction end portion Sc of the steel sheet S in the direction from the upstream side to the downstream side in the conveying direction of the steel sheet S. Note that the pressing mechanism 22A and the pressing mechanism 22B are symmetrical and have the same configuration, and thus the detailed illustration of the pressing mechanism 22B is omitted. The press mechanisms 22A and 22B push up the upper mold 23 and the lower mold 24 as a pair of molds opposed to each other in the vertical direction, and the lower mold 24 together with the tool holder 25 (a direction close to the upper mold 23). A hydraulic cylinder 26 as mold moving means for clamping with a predetermined pressing force, and a clamp mechanism 27 for releasably clamping the steel sheet S inside the upper mold 23 and the lower mold 24 in the width direction; It has. The length in the longitudinal direction of the steel plate S of the lower die 24 and the upper die 23 is shorter than the length of the steel plate S, and the steel plate S is shifted in the longitudinal direction by the transport mechanism 21 (intermittently feeding). However, the bending is performed a plurality of times, and end bending is applied to the width direction ends Sc and Sd of the steel sheet S over the entire length.

  FIG. 5 is a cross-sectional view in the width direction at the same position as FIG. 4, but shows a state where the lower mold 24 is pushed up by the hydraulic cylinder 26 and clamped. When the hydraulic cylinder 26 is advanced from the state before the end bending shown by the broken line, the lower mold 24 is pushed up to the position of the solid line, and the width direction ends Sc and Sd of the steel sheet S are arc-shaped of the upper mold 23. It is bent into a shape along the molding surface. The width at which end bending is performed varies depending on the width of the steel sheet S, but is generally about 100 mm to 400 mm. Here, the case where the clamp mechanism 27 for clamping the steel plate S during end bending is illustrated, but the present invention is not limited to the presence or absence of the clamp mechanism 27.

  FIG. 6 is a cross-sectional view taken along the conveying direction, showing how bending is performed on the width direction ends Sc and Sd of the steel sheet S using a conventional end bending apparatus. The steel sheet S is carried in from the left side of the figure and carried out to the right side. The lower mold 24 has a flat portion 24a that mainly imparts end bending. The flat part 24a refers to a flat part extending in a straight line along the transport direction in a part facing the upper mold 23, and does not mean flat in the cross section in the width direction. The shape of the flat portion 24a in the cross section in the width direction is not particularly limited, and may be an arc shape or a linear shape inclined so as to face the inner side in the width direction. In order to reduce the number of end bending operations, the effective length of the lower mold 24, that is, the length of the flat portion 24a is set to be larger than the width that gives end bending. For example, the length of the flat portion 24a is 3 m to 5 m, and is about 10 times the width giving end bending. Therefore, a plurality of hydraulic cylinders 26 for pushing up the lower mold 24 are usually arranged along the transport direction. In this case, a piston type hydraulic cylinder 26 that generates thrust in both upward and downward directions is generally used in combination with a ram type hydraulic cylinder 26 that generates thrust only during upward movement. In the illustrated example, a piston type hydraulic cylinder 26 is arranged in the center of the conveying direction, and a ram type hydraulic cylinder 26 is arranged before and after the cylinder. In order to apply the pressing force evenly, the center C1 of the flat portion 24a of the lower mold 24 in the conveying direction is designed to coincide with the center C2 of the pressing force by the hydraulic cylinder 26.

  FIG. 6A shows a state in which the steel sheet S is conveyed by a conveying mechanism 21 by a predetermined conveying distance after the press mechanisms 22A and 22B are bent at the width direction ends Sc and Sd of the steel sheet S. Has been. This conveyance distance is set smaller than the length of the flat portion 24a of the lower mold 24. As a result, the rear end portion of the portion to which end bending has already been applied is positioned on the flat portion 24a of the lower mold 24, and the transition portion between the pre-formed portion and the non-formed portion is formed in the next end bend forming. It is surely bent. In FIG. 6 (b), as shown by a broken line, the hydraulic cylinder 26 is a lower metal plate in a state in which the steel plate S is arranged so that the rear end portion of the portion to which end bending has already been applied is positioned on the flat portion 24a. The mold 24 is pushed up, and the end portions Sc and Sd in the width direction of the steel plate S are bent as shown by solid lines. At this time, the range bent in the previous process is also bent again by the amount corresponding to the spring back, and bending deformation also occurs at the upstream side (left side of the drawing) of the steel sheet S that is not located on the flat portion 24a of the lower mold 24. . As an example, FIG. 7 shows the results of end bending applied to a range of 170 mm in the width direction of a steel sheet S having a plate width of 2755 mm and a plate thickness of 28.9 mm, and the shape thereof was investigated. At this time, the length of the flat portion 24a of the lower mold 24 is 3m, and after the first bending of 2.8m from the tip of the plate and measuring the bending angle, the steel plate is conveyed by 2m and the second time. End bending was performed and the bending angle was measured again. Here, the bending angle was obtained from the difference between the inclination angle of the plate end portion 20 mm range and the width center portion measured with an inclinometer. In the first end bending, the bending angle of the front end portion Sa of the steel sheet S increases, and on the upstream side, bending is applied even at a portion off the flat portion 24a, and the length is about 0.6 m. In the next second end bending, the portion bent at the first time is further bent and becomes larger toward the downstream side. On the upstream side, the bending angle slightly increases in the vicinity of the end of the flat portion 24a, and the bend is imparted at a length of about 0.6 m even at a portion off the flat portion 24a as in the first time. At this time, the push-up amount of the lower mold 24 is 2 mm larger on the downstream side than the upstream side (that is, the movement amount (extension distance) of the hydraulic cylinder 26 on the downstream side in the transport direction is the movement of the hydraulic cylinder 26 on the upstream side in the transport direction). This is considered to be because an inclination (rotation in the pitching direction) of 0.04 degrees with the tip side facing upward occurred during end bending.

  Further investigation was conducted to elucidate the cause of this inclination. FIG. 8A schematically shows the distribution of the deformation of the steel sheet S and the bending deformation force (the force that opposes the pressing force at the time of end bending forming, and is also simply referred to as “deformation force” hereinafter) in the first end bending. Indicate. Since the steel plate S does not exist on the downstream side, there is no deformation force, and on the upstream side, the deformation force is generated even at a portion off the flat portion 24a. For this reason, the center C3 of the deformation force is shifted to the upstream side from the center C1 in the transport direction of the flat portion 24a. FIG. 9A shows the case of the second end bending. Since the steel plate S is also present on the downstream side, a deformation force is generated also on the downstream side, but the deformation amount is smaller than that of the springback, and the center C3 of the deformation force is shifted upstream from the center C1 of the flat portion. It becomes the position. When the center C1 of the flat portion 24a coincides with the center C2 of the pressing force by the all hydraulic cylinders 26, as shown in FIG. 8B and FIG. A force for rotating (pitching) of the lower die 24 acts on the downstream side, and the push-up amount of the lower mold 24 increases on the downstream side. FIG. 10 shows a case where end bending is performed on the tail end portion Sb of the steel sheet S. Since there is no steel plate on the upstream side, there is no deformation force, and the center of the deformation force is shifted to the downstream side from the center of the flat portion 24a. When the center of the flat portion coincides with the center of the pressing force by the hydraulic cylinder 26, a force for rotating (pitching) the front side downward acts on the lower mold 24, and the amount of pushing up on the upstream side increases. .

  Thus, in the end bending process, the distribution of the deformation force varies depending on the position in the longitudinal direction of the steel sheet S to be end bent, so that the lower mold 24 is inclined during end bending. Therefore, in the first embodiment of the present invention, the hydraulic cylinders 26 are controlled so that the movement amounts of the respective hydraulic cylinders 26 are substantially equal during end bending of the steel sheet S. The term “substantially equal” means that not only when the movement amounts of the plurality of hydraulic cylinders 26 are completely equal to each other, but also an emergency stop of welding due to excessive fluctuation of the end bending angle in the longitudinal direction does not occur in the subsequent joining process. To the extent these movement amounts are allowed to differ.

  Specifically, the end bending device 20 of the steel plate according to the first embodiment is configured such that the movement amounts of the plurality of hydraulic cylinders 26 are substantially equal when the width direction ends Sc and Sd of the steel plate S are bent. As control means for controlling the cylinder 26, as shown in FIG. 11, a detector (for example, a linear encoder) 62 for detecting the amount of movement (displacement) of the rod 26a of each hydraulic cylinder 26, and the oil to the hydraulic cylinder 26 The servo valve 64 for adjusting the amount and a normal computer having a CPU, a memory, a hard disk, an input device, an output device, etc., and the movement amounts of the hydraulic cylinders 26 are mutually based on the movement amount obtained by the detector 62. A control device 68 that controls the amount of oil supplied from the hydraulic pump 66 to the hydraulic cylinder 26 by displacing the spool of each servo valve 64 so as to be substantially equal. Thereby, when the width direction ends Sc and Sd of the steel plate S are bent, the movement amounts of the respective hydraulic cylinders 26 become substantially equal to each other, that is, the inclination of the lower mold 24 is reduced, so that the end bending shape in the longitudinal direction is reduced. Fluctuations can be reduced.

  Moreover, the manufacturing apparatus of the steel pipe of 1st Embodiment of this invention is equipped with the end bending apparatus 20 of the steel plate of 1st Embodiment demonstrated with reference to FIG. 11 as an end bending apparatus of a steel plate, Cylindrical forming of the steel sheet S by the cylindrical forming apparatus 30 described with reference to FIG. 1 and joining of the width direction ends of the steel sheet S by the joining apparatus 40 to the steel sheet S with little variation in the total length of the end bending shape. Therefore, it is possible to manufacture a steel pipe with little fluctuation in peaking over the entire length.

  In the end bending process, due to the distribution of the deformation force as shown in FIGS. 8 and 9, the press machine body supporting the upper mold 23 and the lower mold 24 is also distorted due to the load difference in the longitudinal direction. The position of the upper mold 23 may vary when viewed in the longitudinal direction. Therefore, in the second embodiment of the present invention, during end bending of the steel sheet S, each hydraulic cylinder 26 is controlled so that the distance between the upper mold 23 and the lower mold 24 is substantially equal in the transport direction. The term “substantially equal” means that not only when the distance between the upper mold 23 and the lower mold 24 is completely equal in the longitudinal direction of the steel sheet S, but the end bending angle is excessive in the longitudinal direction in the subsequent joining step. These distances are allowed to be different to such an extent that an emergency stop of welding due to fluctuation does not occur.

  Specifically, the end bending device 20 of the steel plate of the second embodiment is such that the distance between the upper mold 23 and the lower mold 24 becomes substantially equal in the conveying direction when bending the width direction ends Sc and Sd of the steel sheet S. As a control means for controlling each hydraulic cylinder 26, as shown in FIG. 12, each upper die 23 or each lower die 24 (in the example shown, each of the lower die 24 so as to coincide with the center of each hydraulic cylinder 26 when viewed from the side). It has a rangefinder (for example, laser type rangefinder) 69 provided in the upper mold), a servo valve 64 for adjusting the oil amount to the hydraulic cylinder 26, a CPU, a memory, a hard disk, an input device, an output device, and the like. Based on the distance between the upper mold 23 and the lower mold 24 obtained by each rangefinder 69, the distance between the upper mold 23 and the lower mold 24 is made substantially equal in the transport direction. Control device for controlling each hydraulic cylinder 26 And a 8. Thereby, at the time of bending the end portions Sc and Sd in the width direction of the steel sheet S, the variation of the distance between the upper mold 23 and the lower mold 24 in the longitudinal direction of the steel sheet S, that is, the variation of the pushing amount is the length of the steel sheet S. Since it is reduced in the direction, fluctuations in the end bending shape in the longitudinal direction can be reduced.

  Moreover, the manufacturing apparatus of the steel pipe of 2nd Embodiment of this invention is equipped with the end bending apparatus 20 of the steel plate of 2nd Embodiment demonstrated with reference to FIG. 12 as an end bending apparatus of a steel plate, Cylindrical forming of the steel sheet S by the cylindrical forming apparatus 30 described with reference to FIG. 1 and joining of the width direction ends of the steel sheet S by the joining apparatus 40 to the steel sheet S with little variation in the total length of the end bending shape. Therefore, it is possible to manufacture a steel pipe with little fluctuation in peaking over the entire length.

  Next, the positional relationship between the front end (longitudinal front end) Sa and tail end (longitudinal rear end) Sb of the steel sheet S and the flat portion 24a of the lower mold 24 will be described. Note that the tip end portion Sa and the tail end portion Sb of the steel plate S are portions that are the end portions in the longitudinal direction of the steel pipe product excluding the tab plate St when the tab plate St is present, and Sa and Sb in FIG. It corresponds to. As shown in FIG. 8, in the first end (first pass) end bending, when the front end portion Sa of the steel sheet S is located behind the front end portion of the flat portion 24a, bending deformation is performed on the downstream side. There is no power. For this reason, the center C3 of the deforming force is shifted upstream from the center C2 of the pressing force. By bringing the front end portion Sa of the steel sheet S closer to the front end portion of the flat portion 24a, the amount of deviation between the center C3 of the deformation force and the center C2 of the pressing force is reduced, and fluctuations in the end bending amount can be suppressed. At this time, when the front end portion Sa of the steel plate S is located downstream of the front end portion of the flat portion 24a, the portion where the tab plate St is welded is insufficiently bent, and welding is discontinuous at the portion where the tab plate St moves to the steel plate S. Therefore, the position of the front end portion Sa of the steel plate S is preferably set to a position that does not exceed the front end portion of the flat portion 24. On the other hand, as shown in FIG. 10, when the tail end portion Sb of the steel sheet S is positioned forward of the rear end portion of the flat portion 24 a in the final bending (final pass) end bending, it is more than that. No bending deformation force is generated on the upstream side. For this reason, the center C3 of the deformation force is shifted downstream from the center C2 of the pressing force. By bringing the tail end portion Sb of the steel sheet S closer to the rear end portion of the flat portion 24a, the amount of deviation between the center C3 of the deformation force and the center C2 of the pressing force is reduced, and fluctuations in the end bending amount can be suppressed. At this time, when the tail end portion Sb of the steel plate S is located upstream of the rear end portion of the flat portion 24a, the portion where the tab plate St is welded is insufficiently bent, and welding is performed at the portion where the tab plate St moves to the steel plate S. Since it becomes discontinuous, the position of the tail end portion Sb of the steel sheet S is preferably set to a position that does not exceed the rear end portion of the flat portion 24a.

  Next, another preferred lower mold applicable to the present invention will be described. As shown in FIG. 9, when there is a part to which end bending has already been applied on the downstream side, there is no bending deformation force at the start of end bending, and as a result, the upstream bending deformation force becomes large. On the side, the lower mold 24 and the steel sheet S are not in contact with each other, and the center C3 of the bending deformation force is shifted to the upstream side from the center C2 of the pressing force. For this reason, until the downstream bending deformation occurs, the lower mold 24 is subjected to a rotational force in the direction in which the tip end side is directed upward, and the amount of push-up on the downstream side is large, and the lower mold 24 is inclined. End bending is performed. As a result, the downstream end of the flat portion 24a comes into contact with the already bent portion, for example, as shown in FIG. 7, the second downstream end is deformed, and the downstream end is the first downstream. There is a concern of creating a large step with the bent part. If there is an abrupt shape change, the welding becomes discontinuous at that portion, and defects are generated or the welding is interrupted. Therefore, it is desirable that the change in the bending angle be smooth (small).

  Therefore, in a more preferable aspect of the steel plate end bending method and apparatus and the steel pipe manufacturing method and manufacturing equipment of the present embodiment, as shown in FIG. 13, the lower mold 24, which is one mold, has a flat portion 24a. In this case, the flat portion 24a and the relief portion 24b are preferably connected with a common tangent line. . In this way, by providing the curved relief portion 24b that is continuous with the flat portion 24a on the downstream side, the portion that has been end-bent in the previous pass of the steel sheet S and the portion that has been end-bent in the subsequent pass The step can be made smooth. At this time, the step becomes smoother as the change in the angle of the escape portion 24b becomes smaller as in the involute curve, that is, the curvature changes continuously. However, it is necessary to prevent the downstream end portion of the lower mold 24 from coming into contact with the already bent portion. A similar relief portion 24c can be provided on the upstream side. In this case, it is necessary for the escape portion 24c to prevent the bending deformation length on the rear side from becoming larger than the rear end of the flat portion 24a. In consideration of these points and the end bending amount depending on the width of the steel sheet S, it is preferable to appropriately set the length and angle change of the relief portion 24c. As a guideline, the length and angle change of the relief portion 24c can be set so that the range in which the relief portion 24c contacts the steel sheet S is 1/2 or less of the length that causes bending deformation on the upstream side. .

  Although the embodiments of the present invention have been described based on the illustrated examples, the present invention is not limited to these embodiments, and can be appropriately changed, modified, added, and the like within the scope of the claims. For example, in the illustrated example, the case where the lower mold 24 is pushed up by the hydraulic cylinder 26 to press the width direction ends Sc and Sd of the steel sheet S against the upper mold 23 to perform bending is described. 24 may be configured to be bent in the same direction as the illustrated example by pressing down the upper mold 23 with the fixed mold 24 and the upper mold 23 as a movable mold. Moreover, it is good also as a structure which presses the width direction edge parts Sc and Sd of the steel plate S against the lower metal mold | die 24 as an arrangement | positioning in which the upper metal mold | die 23 is located in the outer side of a bending in the opposite direction to the example of illustration. The number of hydraulic cylinders 26 for clamping the upper mold 23 and the lower mold 24 is not limited, and the mold clamping can be performed using two or four or more hydraulic cylinders 26. Further, the mold moving means for clamping the upper mold 23 and the lower mold 24 is not limited to the hydraulic cylinder 26, but is a mechanical type that performs clamping by converting the rotational movement of the motor into a reciprocating movement by a crank mechanism or the like. A thing may be used.

  In order to confirm the effect of the present invention, the end bending of the steel sheet was performed under different conditions, and the fluctuation in the longitudinal direction of the end bending and the influence on the welding in the subsequent process were investigated, which will be described below.

Example 1
A steel plate having a tensile strength of 500 MPa, a plate width of 1676 mm, a plate thickness of 25.4 mm, and a length of 12 m is prepared by attaching a tab plate having a length of 400 mm and a width of 100 mm to the tip and tail ends, and a steel pipe having an outer diameter of 559 mm is prepared. Manufactured. For end bending, an end bending apparatus of a type in which the lower mold is pushed up by three hydraulic cylinders 26 (mold moving means) arranged at an interval of 1000 mm was used. The central hydraulic cylinder 26 is a piston type having a force of 3MN, and the other two are ram types having a force of 6MN. The hydraulic pressure is supplied to each hydraulic cylinder 26 from each hydraulic pump via a servo valve. The movement amount (displacement amount) of the rod of each hydraulic cylinder 26 is detected by a detector (linear encoder), and the movement amount of the hydraulic cylinder 26 is made substantially equal to each other by a control device (computer) based on this movement amount. A cylinder in which the spool of the servo valve is displaced and the amount of oil supplied from the hydraulic pump to the hydraulic cylinder 26 is controlled is described as “cylinder” in the “control” column of Table 1 below. Further, the distance between the upper die and the lower die is measured by three rangefinders (laser rangefinders) arranged so as to coincide with the center of the hydraulic cylinder 26 when viewed from the side of the end bending device. Based on the measurement result, the control device (computer) controls each hydraulic cylinder 26 so that the distance between the upper mold and the lower mold is substantially equal in the transport direction. ". In the same column, the case where neither the “cylinder” control nor the “interval” control is performed is described as “none”.

  The upper die used for end bending has a molding surface with a radius of curvature of 200 mm, and the flat portion of the lower die is linear with an angle of 40 degrees with respect to the horizontal plane in the cross section in the width direction. The upper mold has the same cross-sectional shape as the entire length. The lower mold has a flat part with a length of 3000 mm and chamfered with R25 mm at both ends in the longitudinal direction (hereinafter referred to as “mold A”), and a continuous part from the flat part with a length of 3000 mm to R1600 mm. Two types having a gentle relief portion (hereinafter referred to as “mold B”) were used.

  The end bending angle (difference between the inclination angle of the plate edge portion 20 mm range and the inclination angle of the width center portion) is set to 33 ° in the width direction end portion 155 mm of the steel plate, and the end bending is performed four times while feeding the steel plate 2600 mm at a time. After performing, the end bending of the 5th time was performed so that the tail end position of a steel plate might stop in a predetermined position. After end bending, the bending angle is measured at a pitch of 0.1 m in the longitudinal direction, the maximum and minimum difference in the center 10 m range in the longitudinal direction is the steady portion fluctuation, the maximum and minimum difference in the total length is the full length fluctuation, The angle difference of the step portion having a large difference is evaluated as the steepness. The bending angle was determined by the difference between the inclination angle of the plate edge portion 20 mm range and the width center portion measured with an inclinometer. Subsequently, U-presses and O-presses were applied, the ends in the width direction of the steel sheets that were formed into a cylindrical shape and end-bent were butted together, and then the abutted width-direction ends were welded together to produce a steel pipe. The peaking of the steel pipe was measured at a pitch of 0.1 m in the longitudinal direction. Peaking is an index of the sharp shape of the butt portion, and as shown in FIG. 14, it is the difference between the regular outer diameter of the steel pipe (that is, a virtual perfect circle) and the actual steel pipe shape. As shown in FIG. 15, when the end bend amount is excessive, the butt portion of the steel pipe enters the inside (minus peaking), and when the end bend amount is excessively small, the butt portion of the steel pipe protrudes outward ( Plus peaking). Similar to the end bending angle, the peaking difference in the central 10 m range in the longitudinal direction was defined as the steady portion fluctuation, and the maximum and minimum difference in the total length as the full length fluctuation.

  Table 1 shows the end bending conditions and the molding results. In the column of the leading end stop position (stop position of the tip end and tail end of the steel plate), the boundary between the steel plate and the tab plate is at the downstream end of the flat portion of the lower mold at the first end bending, and 5 A case where the boundary between the steel plate and the tab plate is positioned at the upstream end of the flat portion of the lower mold during the second end bending is described as “steel plate”. In addition, what is described as “tab” is the case where the entire length of the tab plate is included in the flat portion of the lower mold, and the end of the steel plate is positioned 400 mm inside from the flat portion of the lower mold. .

  As shown in Table 1, conditions 1 to 8, which are invention examples, were able to suppress fluctuations in the end bending angle and were also welded without any problem. The peaking fluctuation of the steel pipe is 1/5 or less of the tolerance ± 3.2 mm required by the API standard, which shows that the shape is excellent. In particular, it can be seen that conditions 5 to 8 in which the “interval” control is performed are superior to conditions 1 to 4 in which the “cylinder” control is performed because the end bending angle and peaking are smaller.

  Further, in the conditions 1, 2, 5, and 6 using the mold B provided with the gentle relief portion, the mold boundary A in which the boundary portion of the feed was hardly visually recognized and the boundary portion of the feed was visually confirmed. The steady-state fluctuation is suppressed to be lower than the conditions 3, 4, 7, and 8 using.

  Furthermore, in conditions 1, 3, 5, and 7 where the longitudinal end portion of the steel plate is stopped so as to be positioned at the end portion of the flat portion, the end bending angle variation of the steady portion and the end bending angle variation of the full length are the same. In addition, the peaking fluctuation of the steady part and the peaking fluctuation of the full length are the same, and the end bending amount is the same over the entire length, whereas the longitudinal end of the steel plate is placed inside the flat part of the lower mold. In the conditions 2, 4, 6, and 8 positioned at, the end bending amount at the end portion was increased, and the variation in the entire length was increased.

  On the other hand, in the condition 9 in which the control according to the present invention was not performed, various fluctuations were large as compared with the invention example, and the sudden stop of the shape of the feed boundary exceeded the copying limit of the welding torch, so that the welding was stopped urgently.

(Example 2)
A steel plate having a tensile strength of 550 MPa, a plate width of 2753 mm, a plate thickness of 38.1 mm, and a length of 12 m is prepared by attaching a tab plate having a length of 400 mm and a width of 100 mm to the tip and tail ends, and a steel pipe having an outer diameter of 914 mm is prepared. Manufactured. The upper die used for end bending had a forming surface with a radius of curvature of 335 mm, and end bending was performed in the range of 180 mm in the width direction end of the steel plate with an end bending angle of 24 degrees. The other end bending conditions, such as an end bending apparatus, a lower mold, and a steel sheet feed amount, were the same as those in Example 1. After the end bending, the bending angle was measured, and then formed into a cylindrical shape by a bending press method and welded to obtain a steel pipe.

  Table 2 shows the end bending conditions and the molding results. The items and notations in Table 2 are the same as in Example 1.

  As shown in Table 2, in the conditions 1 to 8 which are invention examples, the fluctuation of the end bending angle was suppressed, and welding was performed without any problem. It can be seen that the peaking fluctuation of the steel pipe is excellent in the shape of 1/6 or less of the tolerance ± 3.2 mm required by the API standard.

  In particular, it can be seen that conditions 5 to 8 in which the “interval” control is performed are superior to conditions 1 to 4 in which the “cylinder” control is performed, since the end bending angle and peaking fluctuation are small.

  Further, in the conditions 1, 2, 5, and 6 using the mold B provided with the gentle relief portion, the mold boundary A in which the boundary portion of the feed was hardly recognized visually and the boundary portion of the feed was visually confirmed. The fluctuation of the stationary part is suppressed to be lower than the conditions 3, 4, 7, and 8 using.

  Furthermore, in conditions 1, 3, 5, and 7 where the longitudinal end portion of the steel plate is stopped so as to be positioned at the end portion of the flat portion, the end bending angle variation of the steady portion and the end bending angle variation of the full length are the same. In addition, the peaking fluctuation of the steady part and the peaking fluctuation of the full length are the same, and the end bending amount is the same over the entire length, whereas the longitudinal end of the steel plate is placed inside the flat part of the lower mold. In the conditions 2, 4, 6, and 8 positioned at, the end bending amount at the end portion was increased, and the variation in the entire length was increased.

  On the other hand, in the condition 9 in which the control according to the present invention was not performed, various fluctuations were large as compared with the invention example, and the sudden stop of the shape of the feed boundary exceeded the copying limit of the welding torch, so that the welding was stopped urgently.

(Example 3)
A steel plate having a tensile strength of 500 MPa, a plate width of 3232 mm, a plate thickness of 38.1 mm, and a length of 12 m is prepared by attaching a tab plate having a length of 400 mm and a width of 100 mm to the tip and tail ends, and a steel pipe having an outer diameter of 1067 mm. Manufactured. The upper mold used for end bending has a molding surface with a radius of curvature of 400 mm. End bending was performed in the range of 195 mm in the width direction end of the steel plate with an end bending angle of 22 degrees as a target. Other end bending conditions, such as an end bending apparatus, a lower mold, and a steel sheet feed amount, were the same as those in Example 1. After bending the end, the bending angle was measured, a U press and an O press were applied to form a cylindrical shape, and welded to obtain a steel pipe.

  Table 3 shows the end bending conditions and the molding results.

  As shown in Table 3, conditions 1 to 8, which are invention examples, suppressed fluctuations in the end bending angle, and welding was performed without any problem. It can be seen that the shape of the steel pipe peaking fluctuation is excellent, as 1/5 or less of the tolerance ± 3.2 mm required by the API standard.

  In particular, it can be seen that conditions 5 to 8 in which the “interval” control is performed are superior to conditions 1 to 4 in which the “cylinder” control is performed, since the end bending angle and peaking fluctuation are small.

  Further, in the conditions 1, 2, 5, and 6 using the mold B provided with the gentle relief portion, the mold boundary A in which the boundary portion of the feed was hardly recognized visually and the boundary portion of the feed was visually confirmed. The fluctuation of the stationary part is suppressed to be lower than the conditions 3, 4, 7, and 8 using.

  Furthermore, in conditions 1, 3, 5, and 7 where the longitudinal end portion of the steel plate is stopped so as to be positioned at the end portion of the flat portion, the end bending angle variation of the steady portion and the end bending angle variation of the full length are the same. In addition, the peaking fluctuation of the steady part and the peaking fluctuation of the full length are the same, and the end bending amount is the same over the entire length, whereas the longitudinal end of the steel plate is placed inside the flat part of the lower mold. In the conditions 2, 4, 6, and 8 positioned at, the end bending amount at the end portion was increased, and the variation in the entire length was increased.

  On the other hand, in the condition 9 in which the control according to the present invention was not performed, various fluctuations were large as compared with the invention example, and the sudden stop of the shape of the feed boundary exceeded the copying limit of the welding torch, so that the welding was stopped urgently.

  According to the present invention, it is possible to obtain an end bending shape with little variation in the entire length.

DESCRIPTION OF SYMBOLS 10 Edge mirror 20 End bending apparatus of steel plate 30 Cylindrical forming apparatus 30A U press 30B O press 30C Bending press 40 Joining apparatus 50 Mechanical expander 21 Conveyance mechanism 21a Conveyance roll 22A, 22B Press mechanism 23 Upper die 24 Lower die 24a Flat Part 24b, 24c relief part 26 hydraulic cylinder 62 detector 64 servo valve 66 hydraulic pump 68 control device 69 range finder S steel plate Sa tip part Sb tail end part Sc, Sd width direction end part St tab plate

Claims (14)

A pair of molds arranged corresponding to the widthwise ends of the steel sheet;
A plurality of mold moving means for relatively moving the pair of molds in the proximity direction;
Using a steel plate end bending device comprising a transport mechanism that transports the steel sheet as a transport direction along the longitudinal direction thereof,
While intermittently transporting the steel plate by the transport mechanism, by bending the steel plate in the width direction by moving the pair of molds relatively in the proximity direction, the width direction end of the steel plate is performed a plurality of times. It is an end bending method of a steel plate that performs bending over the entire length of the part,
An end bending method for a steel sheet, characterized in that the amount of movement of the plurality of mold moving means is controlled so that the bending angle of the steel sheet is substantially equal in the longitudinal direction of the steel sheet during bending of the end portion in the width direction of the steel sheet. . A pair of molds arranged corresponding to the widthwise ends of the steel sheet;
A plurality of mold moving means for relatively moving the pair of molds in the proximity direction;
Using a steel plate end bending device comprising a transport mechanism that transports the steel sheet as a transport direction along the longitudinal direction thereof,
While intermittently transporting the steel plate by the transport mechanism, by bending the steel plate in the width direction by moving the pair of molds relatively in the proximity direction, the width direction end of the steel plate is performed a plurality of times. It is an end bending method of a steel plate that performs bending over the entire length of the part,
The plurality of mold moving means are controlled so that the amount of movement of the plurality of mold moving means is substantially equal during bending of the width direction end portion of the steel sheet. End bending method for steel sheet. A pair of molds arranged corresponding to the widthwise ends of the steel sheet;
A plurality of mold moving means for relatively moving the pair of molds in the proximity direction;
Using a steel plate end bending device comprising a transport mechanism that transports the steel sheet as a transport direction along the longitudinal direction thereof,
While intermittently transporting the steel plate by the transport mechanism, by bending the steel plate in the width direction by moving the pair of molds relatively in the proximity direction, the width direction end of the steel plate is performed a plurality of times. It is an end bending method of a steel plate that performs bending over the entire length of the part,
2. The plurality of mold moving means are controlled so that the distance between the pair of molds is substantially equal in the conveying direction during bending of the width direction end of the steel plate. End bending method of steel plate.   The one mold has a relief portion formed of a curved surface provided adjacent to the upstream side and the downstream side of the flat portion in the transport direction, and the flat portion and the relief portion are common to each other. The end bending method for a steel sheet according to any one of claims 1 to 3, wherein the end bending method is performed with a tangent line.   In the first pass of bending to the width direction end of the steel plate, the front end of the steel plate in the transport direction is positioned at the front end of the flat portion. The end bending method of the steel plate as described in any one of these.   The last pass of the bending to the width direction end of the steel plate is a position where the tail end of the steel plate in the transport direction is aligned with the rear end of the flat portion. The end bending method of the steel plate as described in any one of the above. A pair of molds arranged corresponding to the widthwise ends of the steel sheet, mold moving means for relatively moving the pair of molds in the proximity direction, and a direction along the longitudinal direction of the steel sheet in the conveying direction A steel sheet end bending apparatus, and the steel sheet is intermittently transported by the transport mechanism while moving the pair of molds relatively in the proximity direction. By bending the end part a plurality of times, an end bending step of the steel sheet that performs bending over the entire length in the width direction end of the steel sheet,
A cylindrical forming step of forming a steel sheet bent at both ends in the width direction into a cylindrical shape and abutting the width direction ends of the steel sheets,
A joining step of welding end portions in the width direction of the butted steel sheets, and a method of manufacturing a steel pipe,
A method of manufacturing a steel pipe, comprising: controlling a plurality of mold moving means so that movement amounts of the plurality of mold moving means are substantially equal during bending of an end portion in the width direction of a steel plate. A pair of molds arranged corresponding to the widthwise ends of the steel sheet, mold moving means for relatively moving the pair of molds in the proximity direction, and a direction along the longitudinal direction of the steel sheet in the conveying direction A steel sheet end bending apparatus, and the steel sheet is intermittently transported by the transport mechanism while moving the pair of molds relatively in the proximity direction. By bending the end part a plurality of times, an end bending step of the steel sheet that performs bending over the entire length in the width direction end of the steel sheet,
A cylindrical forming step of forming a steel sheet bent at both ends in the width direction into a cylindrical shape and abutting the width direction ends of the steel sheets,
A joining step of welding end portions in the width direction of the butted steel sheets, and a method of manufacturing a steel pipe,
A method of manufacturing a steel pipe, comprising: controlling the plurality of mold moving means so that a distance between the pair of molds is substantially equal in the conveying direction during bending of a width direction end of a steel plate. A pair of molds arranged corresponding to the widthwise ends of the steel sheet;
Mold moving means for relatively moving the pair of molds in the proximity direction;
A transport mechanism that transports the steel sheet as a transport direction in the direction along the longitudinal direction thereof, and
While intermittently transporting the steel plate by the transport mechanism, by bending the steel plate in the width direction by moving the pair of molds relatively in the proximity direction, the width direction end of the steel plate is performed a plurality of times. A steel sheet end bending apparatus that performs bending over the entire length of the part,
An end of a steel sheet comprising a control means for controlling the plurality of mold moving means so that the amount of movement of the plurality of mold moving means becomes substantially equal during bending of the width direction end of the steel sheet. Bending device. A pair of molds arranged corresponding to the widthwise ends of the steel sheet;
Mold moving means for relatively moving the pair of molds in the proximity direction;
A transport mechanism that transports the steel sheet as a transport direction in the direction along the longitudinal direction thereof, and
While intermittently transporting the steel plate by the transport mechanism, by bending the steel plate in the width direction by moving the pair of molds relatively in the proximity direction, the width direction end of the steel plate is performed a plurality of times. A steel sheet end bending apparatus that performs bending over the entire length of the part,
A control means for controlling the plurality of mold moving means is provided so that the distance between the pair of molds becomes substantially equal in the transport direction during bending of the width direction end of the steel sheet. End bending device.   The one mold has a relief portion formed of a curved surface provided adjacent to the upstream side and the downstream side of the flat portion in the transport direction, and the flat portion and the relief portion are common to each other. The steel sheet end bending apparatus according to claim 9 or 10, wherein the end bending apparatus is connected with a tangent line. A pair of molds arranged corresponding to the widthwise ends of the steel sheet, mold moving means for relatively moving the pair of molds in the proximity direction, and conveying the steel sheet in a direction along its longitudinal direction A bending mechanism that moves the pair of molds relatively in the proximity direction while intermittently conveying the steel sheet by the conveying mechanism. By performing a plurality of times, an end bending device for a steel sheet that performs bending over the entire length of the width direction end of the steel sheet, and
A cylindrical forming apparatus that forms a steel plate that is bent at both ends in the width direction into a cylindrical shape, and abuts the end portions in the width direction of the steel plate;
A steel pipe manufacturing facility comprising: a joining device that welds the widthwise ends of the abutted steel sheets;
The end bending apparatus for the steel sheet includes a control unit that controls the plurality of mold moving units so that the movement amounts of the plurality of mold moving units become substantially equal when the width direction end of the steel sheet is bent. Steel pipe manufacturing equipment characterized by that. A pair of molds arranged corresponding to the widthwise ends of the steel sheet, mold moving means for relatively moving the pair of molds in the proximity direction, and conveying the steel sheet in a direction along its longitudinal direction A bending mechanism that moves the pair of molds relatively in the proximity direction while intermittently conveying the steel sheet by the conveying mechanism. By performing a plurality of times, an end bending device for a steel sheet that performs bending over the entire length of the width direction end of the steel sheet, and
A cylindrical forming apparatus that forms a steel plate that is bent at both ends in the width direction into a cylindrical shape, and abuts the end portions in the width direction of the steel plate;
A steel pipe manufacturing facility comprising: a joining device that welds the widthwise ends of the abutted steel sheets;
The end bending apparatus for the steel plate includes a control means for controlling the plurality of mold moving means so that a distance between the pair of molds is substantially equal in the conveying direction at the time of bending the end portion in the width direction of the steel plate. A steel pipe manufacturing facility comprising:   The one mold has a relief portion formed of a curved surface provided adjacent to the upstream side and the downstream side of the flat portion in the transport direction, and the flat portion and the relief portion are common to each other. The steel pipe manufacturing equipment according to claim 12 or 13, wherein the steel pipe manufacturing equipment is connected with a tangent line.

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