JPH02127926A - Bend straightening method for forming material for welded tube - Google Patents

Abstract

PURPOSE:To manufacture a welded tube being free from a torsion in a forming stage, and also, having a stable quality by bringing a rolling reduction device to single rolling reduction in the width direction of a forming material by a portion corresponding to a bend quantum detected by a bend detecting device, and straightening the bend of the forming material. CONSTITUTION:A bend quantum of a forming material 5 is detected by a bend detecting device 12. Based on its detected bend quantum, a leveler 11 is brought to single rolling reduction in the width direction of the forming material so that its bend is eliminated. Accordingly, since an edge part of the forming material 5 is not constrained, the bend can be straightened without damaging the edge part. As a result, by straightening the bend, a torsion at the stage of forming is prevented, and also, since the edge part is not damaged, a welded tube having a stable quality can be manufactured without deteriorating the welding quality.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for straightening bends in a welded pipe forming material.

[Prior art] A molded welded pipe is produced by forming a band-shaped material into a tubular shape using forming zones such as breakdown forming, intermediate forming, fin pass forming, and squeeze forming. Manufactured by butting and welding.

However, in the welded pipe manufacturing line as described above, if there is a bend in the formed material at the strip stage, the formed material at the tubular forming stage will be twisted, and it will take a long time to thread the tip, which will reduce productivity. Significantly inhibits.

The following (1) and (2) have been proposed as methods for preventing twisting of the molded material during the tubular molding step.

(1) As described in Japanese Patent Application Laid-open No. 83-108812,
A torsion detection device for the forming material placed in the intermediate forming zone of the welded pipe detects the amount of twist, and a guide roller placed in front of the final stand in the previous breakdown forming zone is moved left and right by an amount equivalent to this amount of twist. A method for correcting torsion in molded materials.

(2) As described in JP-A-63-108913,
A misalignment detection device, a movable side guide, and a fixed side guide are installed at the front of the breakdown molding zone, and the misalignment detection device detects the amount of misalignment of the molded material. A method of preventing and correcting twisting of the molded material by displacing the molded material using a movable side guide.

[Problems to be Solved by the Invention] However, in both of the above conventional methods (+) and (2), the edge portion of the molded material is forcibly restrained with a guide roller or a movable side guide to correct twisting. As a result, one edge of the molded material, which is subject to strong restraint, is damaged, resulting in the following disadvantages.

■A flash is formed on one edge due to strong restraint, and this flash is eroded during welding and remains as an indentation flaw on the tube surface.

(Buckling occurs at one edge due to strong restraint, which causes poor abutment between both edges, resulting in defective welding.)

■The left and right wall thickness of the welded part becomes uneven, which causes poor heat input, resulting in defective welding.

The purpose of the present invention is to correct the bending of the formed material at the strip stage without damaging the edges, thereby producing a welded pipe that is free from twisting during the forming stage and has stable quality. do.

[Means for Solving the Problems] The method for straightening the bending of a welded pipe forming material of the present invention includes providing a rolling device on the entry side of a forming zone for forming a strip-shaped material into a tubular shape, and installing a rolling device on the rear surface of the rolling device. A bending detection device for the formed material is arranged, the direction detection device detects the bending of the formed material, and the rolling device described above is rolled down one side in the width direction of the formed material by an amount equivalent to the amount of bending, thereby detecting the bending of the formed material. It was designed to correct this.

[Effect] The present invention corrects the bending as follows.

■For example, the bend detection device measures the positions a and b of the left and right edges of the molded material relative to the path center, and as a result, the amount of deviation (a-b)/
2 is detected as the amount of bending.

(2) Based on the amount of bending detected in (2) above, the rolling down device is used to reduce one side of the molded material in the width direction so that this bending is eliminated.

FIG. 7 is a diagram showing an example of the relationship between the rolling down conditions of the rolling down device (leveler) and the amount of correction of bending of the formed material (coil material). 1 (t1t2) /l IX indicating the reduction condition
At 100%, tl is the thickness of the edge of the forming material on the operator side of the rolling down device, t2 is the thickness of the edge of the forming material on the driving side, t is the nominal thickness of the coil material, and the amount of bending correction is [+iw+/100100O of the coil material] Established. If the difference in plate thickness between the left and right edges exceeds a certain value under the above rolling conditions, this difference in plate thickness will actually cause a decline in welding quality. It is necessary to perform one-sided pressure.

According to the invention according to (1) and (2) above, since no restraint is applied to the edge portion of the molded material, bending can be corrected without damaging the edge portion. Therefore, by correcting the bending, twisting during the forming step is prevented, and by not damaging the edges, a stable welded pipe of one quality can be manufactured without degrading the welding quality.

[Example] Fig. 1 is a schematic diagram showing an example of an ERW welded pipe manufacturing line to which the present invention is applied, Fig. 2 is a schematic diagram showing an example of a rolling down device, and Fig. 3 is a schematic diagram showing an example of a bend detection device. Figure 4 is a schematic diagram showing the breakdown forming process, Figure 5 is a schematic diagram showing the fin pass forming process, Figure 6 is a schematic diagram showing the squeeze forming process, and Figure 7 is the rolling conditions of the rolling down device. FIG. 3 is a diagram showing an example of the relationship between the curve correction amount of the molded material and the bending correction amount of the molded material.

The electric resistance welded pipe manufacturing apparatus 10 shown in FIG. 1 includes a breakdown forming zone 1 (see FIG. 4), an intermediate forming zone 2, a fin pass forming zone 3 (see FIG. 5), and a squeeze forming zone 4 (see FIG. 6). ), the band-shaped forming material 5 is formed into a tubular shape in each forming zone, and the front edges of the formed band plates are abutted and welded to form an electric resistance welded pipe 6.
Manufacture.

Here, the electric resistance welded pipe manufacturing apparatus IO is provided with a leveler 11 as a rolling down device on the entry side of each of the forming zones. As shown in FIG. 2, the leveler 11 is constructed by arranging a plurality of upper and lower rolls in a staggered manner, and is capable of single-handedly lowering the molded material 5 in the width direction using the lowering cylinders 100 provided at the left and right positions. ing.

As for the configuration of the rolling down device, (1) a skin pass mill consisting of a pair of upper and lower rolls may be installed in place of the leveler 11, or (2) in addition to the leveler 11, a skin pass mill IIA may be installed in front of the leveler 11. May be juxtaposed.

Further, the above-mentioned electric resistance welded pipe manufacturing apparatus 10 includes the above-mentioned leveler 11.
Bending detection device 1 for detecting bending of molded material 5 on the rear surface of
For example, the zero bend detection device 12 in which the
It is composed of an image sensor as shown in the figure, and the molded material 5
The positions 11a and 11b of the left and right edge portions with respect to the path center are measured, and as a result, the amount of deviation (a-b)/2 of the center of the molded material relative to the path center is detected as the amount of bending.

Further, the electric resistance welded pipe manufacturing apparatus IO includes a control device 13. The control device 13 obtains the detection result of the bend detection device 112 and controls the leveler 11 based on this detection result. That is, the control device 13 lowers the leveler 11 on one side in the width direction of the molded material by an amount corresponding to the amount of bending detected by the bending detection bag N12, thereby correcting the bending of the molded material 50.

At this time, the rolling conditions of the leveler 11 are selected within the practical (appropriate) range defined in FIG. 7 described above.

A coil edge processing device 14 for trimming both edges of the molded material 5 is installed on the exit side of the bend detection device 12 and on the entrance side of the breakdown molding zone l.

Next, the operation of the above embodiment will be explained.

(2) The bending detection device 12 detects the bending amount (a-b)/2 of the molded material 5 as described above.

(2) Based on the amount of bending detected in (2) above, the leveler 11 is rolled down one side in the width direction of the molded material so that this bending is eliminated.

According to (1) and (2) above, since no restraint is applied to the edge portion of the molded material 5, the bending can be corrected without damaging the edge portion.

Therefore, by correcting one bend, twisting in the forming stage is prevented, and the edge portion is not damaged, so that a stable welded pipe 6 of one quality can be manufactured without impairing the weld quality.

Next, concrete implementation results of the present invention will be explained. Pipe type AP15LX 80, outer diameter 558.8*■, wall thickness 7.9
2ts■ (Coil material dimensions width 1775 Soho, wall thickness 7.82
The present invention was applied to the production of electric resistance welded pipes (Layers). result,
The bending amount of the molded material is corrected from the conventional O.15 mm/m to 0.02 m/m by the present invention, and it is possible to manufacture high-grade thin-walled large-diameter pipes with stable quality and no twisting during the molding stage. Admitted.

[Effects of the Invention] As described above, according to the present invention, by correcting the bending of the molded material at the stage of the strip without damaging its edges, there is no twisting at the stage of molding and the quality can be improved. Can produce stable welded pipes.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an ERW welded pipe manufacturing line to which the present invention is applied, FIG. 2 is a schematic diagram showing an example of a rolling down device, and FIG. 3 is a schematic diagram showing an example of a bending detection device. Fig. 4 is a schematic diagram showing the breakdown forming process, Fig. 5 is a schematic diagram showing the fin pass forming process, Fig. 6 is a schematic diagram showing the squeeze forming process, and Fig. 7 is a schematic diagram showing the rolling conditions of the rolling device and the molding material. It is a diagram showing an example of the relationship with the amount of bend correction. 5... Molding material, 6... ERW welded pipe, 10... ERW welded pipe manufacturing device. 11...Leveler (downloading device). 11A...Skin pass mill (pressure bag M), 12...
Bending detection device. 13...Control device. Agent Patent Attorney Osamu Shiokawa Figure 2 (A) (B) Figure 3 Figure 4 Figure 5 Construction Figure 6

Claims (1)

[Claims] (1) A rolling down device is provided on the entry side of a forming zone in which a band-shaped material is formed into a tube, and a bending detection device for the forming material is arranged at the rear of the rolling device, and the bending detection device detects the bending of the forming material. A method for correcting a bend in a welded pipe forming material, wherein the bending device detects the bending amount, and lowers one side of the forming material in the width direction of the forming material by an amount equivalent to the bending amount, thereby correcting the bend in the forming material.