JP2015074007A - Electroseamed steel pipe and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means for assisting an electroseamed steel pipe to identify a seam part without deteriorating flaw detection accuracy of ultrasonic flaw detection of a whole cross section of the seam part with MP-UT and without causing excessive interference between a cutting tool used for inner surface bead cutting and a pipe inner surface.SOLUTION: In an electroseamed steel pipe having a seam part 5 being a junction by electric resistance welding 3, recesses 15 arranged in parallel in a plurality on two virtual parallel lines 13 holding the seam part 5 therebetween on the pipe outer surface side are formed in both seam side parts 12.

Description

  The present invention relates to an electric resistance steel pipe and a manufacturing method thereof, and more particularly, to an electric resistance steel pipe provided with means for supporting identification of a seam portion which is a joint portion by electric resistance welding and a manufacturing method thereof.

  For example, as shown in FIG. 3, an electric resistance forging pipe method for producing an electric resistance steel pipe, while continuously feeding the band steel 1, rounds the width of the band steel 1 by roll forming 2, and both ends of the rounded width are electrically connected. A series of pipes 4 are formed by joining by sewing welding 3, and external bead cutting 6 is performed for cutting and removing the external bead that is formed on the pipe external surface side of the seam portion 5 that is the joined part. Process. In addition, along with the outer surface bead cutting 6, there is a case where inner surface bead cutting 7 for cutting and removing the inner surface bead formed on the inner surface side of the pipe of the seam portion 5 is performed. The combined use of the outer bead cutting 6 and the inner bead cutting 7 is called inner / outer bead cutting.

When the ERW steel pipe is subjected to secondary processing such as plastic processing such as bending processing or pipe length direction welding processing between the plate end and the outer surface of the pipe after pipe making, the seam portion is in a position suitable for each processing form. There are many cases where it is necessary to arrange and process. Such an ERW steel pipe for secondary processing is desired to be able to identify the seam portion at the processing site.
Conventionally, in the case of an electric resistance welded steel pipe not provided with means for supporting identification of the seam portion, the identification of the seam portion has been performed by color, magnetism, or shape, but these have the following difficulties (patents) Reference 1 [0005]).

In other words, in the identification by color, the electro-welded welded part as-formed is discolored black compared to the other parts due to oxidation, so this black part can be identified as a seam part, but tempering etc. When the heat treatment is performed, the entire surface of the tube body turns black, and the seam portion cannot be identified.
In the identification by magnetism, the seam part at the stage of pipe forming has a magnetic characteristic difference due to the metal structure difference with other parts, so the seam part can be identified by detecting the magnetic characteristic difference, but tempering after pipe forming When the heat treatment such as the above is performed, the difference in the metal structure disappears, the magnetic characteristic difference cannot be detected, and the seam portion cannot be identified.

In identification by shape, the seam portion is a seam portion in which the outer surface portion subjected to the outer surface bead cutting is recessed as compared with other portions, and this dent can be recognized even after heat treatment, so that the dent is recognized after heat treatment. However, when the tube is drawn, the outer peripheral shape of the tube body becomes uniform, and the dent cannot be recognized, and the seam portion after the tube drawing cannot be identified.
On the other hand, as a conventional technique provided with another means for supporting identification of the seam portion, for example, a rolling tool is pressed against the cutting surface formed by cutting and removing the bead on the pipe outer surface side of the seam portion. There is a proposal of a method of forming (referred to as conventional method A) (see the claims of Patent Document 1).

  According to the conventional method A, the uneven portion formed as a separate means for supporting the identification of the seam portion remains without being erased even after the heat treatment or after the tube drawing. The part can be easily identified.

JP 2012-40581 A

  However, in the conventional method A, since the concave and convex portion is formed on the cut surface of the seam by cutting the outer surface bead, the multi-probe ERW steel pipe UT technology (Iizuka et al .: JFE technology) is used in the downstream inspection process. When ultrasonic flaw detection is performed on the entire cross section of the seam part according to report No. 9 (see August 2005, p. 40 to 45, hereinafter abbreviated as MP-UT), the uneven processing part interfering with the seam part is detected. There is a problem that it is erroneously detected as a flaw (defect) and the flaw detection accuracy is deteriorated.

  In the conventional method A, the tubular body is bent or flattened by pressing the rolling tool against the cutting surface on the pipe outer surface side. On the other hand, in the manufacturing process of the ERW steel pipe, the inner surface bead cutting may be performed together with the outer surface bead cutting. In this case, if the tube is bent or flattened by the pressing of the rolling tool, the cutting tool used for the inner surface bead cutting and the inner surface of the tube excessively interfere with each other, leading to excessive thinning or damage to the cutting tool. There is also a problem.

  In view of the problems of the conventional method A, the present invention does not deteriorate the flaw detection accuracy of ultrasonic flaw detection of the entire cross section of the seam portion by MP-UT, and the cutting tool used for inner surface bead cutting and the tube inner surface are excessive. An object (problem to be solved by the present invention) is to provide means for assisting identification of a seam portion in an ERW steel pipe without causing interference.

The present invention made to solve the above-mentioned problems is as follows.
(1) In an ERW steel pipe having a seam portion that is a joint portion by ERW welding, a plurality of recesses arranged on two virtual parallel lines sandwiching the seam portion in the middle on the tube outer surface side are formed on both sides of the following seam. ERW steel pipe characterized by that.
The both sides of the seam mean that the pipe circumferential direction angle θ, in which one direction of bi-directional rotation around the tube axis of the tube body is 0 ° and the other direction is positive and the other direction is positive, The angle Φ defining the region is Φ = 45 °, and the region on the positive and negative sides of the angle range where −Φ ≦ θ ≦ Φ overlaps the base material portion of the tubular body.
(2) While continuously feeding the steel strip, the width of the steel strip is rounded by roll forming, and both ends of the rounded width are joined by electric-welding welding to form a tubular body, which is a joint by electric-welding welding In the method of manufacturing an ERW steel pipe for cutting and removing the bead on the pipe outer surface side or further the pipe inner surface side of the seam part,
After removing the bead on the pipe outer surface side or further on the pipe inner surface side of the seam part,
A rolling tool is pressed against the pipe outer surface side of both sides of the seam described in (1) to form a plurality of recesses arranged on two virtual parallel lines sandwiching the seam portion in the middle on the pipe outer surface side. The manufacturing method of ERW steel pipe.
(3) While continuously feeding the steel strip, the width of the steel strip is rounded by roll forming, and both ends of the rounded width are joined by electric-welding welding to form a tube, which is a joint portion by electric-welding welding In the method of manufacturing an ERW steel pipe for cutting and removing the bead on the pipe outer surface side or further the pipe inner surface side of the seam part,
Before rolling the width of the steel strip by roll forming, both ends of the steel strip in the width direction are arranged on the side of the steel strip on the side of the steel strip and the gear-shaped roll arranged on the side of the steel strip on the side of the pipe outer surface. By pressing in the strip thickness direction with a flat roll
The indentation which becomes a recessed part as described in said (1) is formed in the steel strip surface side of the steel strip width direction both ends which become the pipe | tube outer surface side of the seam both side part as described in said (1). A method for manufacturing ERW steel pipes.

  According to the present invention, the accuracy of ultrasonic flaw detection of the entire cross section of the seam portion by MP-UT is not deteriorated, and excessive interference between the cutting tool used for inner surface bead cutting and the inner surface of the pipe is not caused. Means for supporting the identification of the seam portion can be provided in the steel pipe. Moreover, since the recessed part used as the means which assists identification of the said seam part is formed in the base material part which is softer than a seam part and an ERW welding heat-affected part, the installation for forming a recessed part can be simplified more. There is also an effect.

It is the schematic which shows an example of the ERW steel pipe which concerns on this invention. It is A view of FIG. It is the schematic which shows an example of an electric sewing pipe method. It is the schematic which shows an example (an example different from the example of FIG. 2) of the ERW steel pipe which concerns on this invention. It is the schematic which shows an example of method M1 among the manufacturing methods of the ERW steel pipe which concerns on this invention. FIG. 6 is a B view of FIG. 5. It is the schematic which shows an example of method M2 among the manufacturing methods of the ERW steel pipe which concerns on this invention. FIG. 8 is a C view of FIG. 7.

  As shown in FIG. 1 and FIG. 2, for example, the ERW steel pipe according to the present invention is an ERW steel pipe having a seam portion 5 which is a joint portion by ERW welding. The pipe circumferential direction angle θ with one direction of bidirectional rotation starting from 0 ° as positive (+) and the other direction as negative (−) is defined as an angle Φ that defines the range of the angle Φ = 45 °, The seam portion 5 is sandwiched between the seam opposite sides 12 which are portions formed by overlapping regions of the positive and negative sides of the angle range where −Φ ≦ θ ≦ Φ overlaps the base material portion 16 of the tube body 4 on the tube outer surface side. A plurality of concave portions 15 are formed on two virtual parallel lines 13. In FIG. 1, 11 is an electric-welding welding heat affected zone. The concave portion 15 is not formed in the seam portion 5 and the ERW welding heat affected zone 11.

  The recess 15 does not disappear in any of the heat treatment, the diameter reduction rolling, and the tube drawing, and can be easily detected visually or with an optical sensor. Therefore, if the concave portion 15 is detected and a plurality of the concave portions 15 are connected, the two virtual parallel lines 13 can be specified, and the seam portion 5 passes through an intermediate position between the two specified virtual parallel lines 13. Since it can be recognized, the concave portion 15 becomes an effective means for supporting the identification of the seam portion 5 at the secondary processing site.

In addition, the recess 15 is formed on both side portions 12 of the seam outside the region of the seam portion 5 and the ERW welding heat-affected zone 11, and does not interfere with the seam portion 5. The flaw detection accuracy of sonic flaw detection is not deteriorated.
Here, when Φ is a 45 ° greater than in the case of is a circumferential direction of the pipe angle of the recess 15 theta theta _P is also made of a theta _P> 45 ° is acceptable, theta _P> 45 °, two Since the interval between the virtual parallel lines 13 of the book is too wide, and the inclination of the concave portion 15 when viewed from directly above the seam portion 5 is too large, it becomes difficult to detect the concave portion 15 by visual observation or an optical sensor. Φ = 45 °. From the viewpoint of facilitating the detection, Φ is preferably Φ = 30 °, more preferably Φ = 15 °.

Further, from the viewpoint of ease of detection, the recess 15 has a pitch of 2 to 20 mm for each of the two virtual parallel lines 13 and the maximum dimension in plan view of each of the recesses 15. Is preferably 0.5 to 1.0 mm.
In addition, if the depth of the recess 15 (the dimension in the tube thickness direction) is too shallow, the detection of the recess 15 becomes difficult. On the other hand, if the depth is too deep, the mechanical performance of the tubular body 4 is likely to be impaired. It is preferable to be 10 mm or more and 15% or less of the tube thickness.

  Further, in the example of FIG. 2, a configuration in which a plurality of concave portions 15 arranged in the first of the two virtual parallel lines 13 and a plurality of concave portions 15 arranged in the second line are at the same position in the tube axis direction (referred to as form I). However, the present invention is not limited to this form I, and the first concave portion 15 and the second concave portion 15 of the two virtual parallel lines 13 are located at different positions in the tube axis direction. It may be in the form (referred to as Form II).

  Further, for example, as shown in FIG. 4, a mode in which “1/2 position of the pitch in the tube axis direction” is selected from the “different positions in the tube axis direction” referred to in the mode II (form IIA and In this case, the form IIA has a pitch of the concave portion 15 in the seam both sides 12 as a half of that of the form I (see FIG. 2) as compared with the form I (see FIG. 2). Therefore, in particular, when the pipe body is cut to a predetermined length after the outer surface bead cutting or the inner and outer surface bead cutting, and then subjected to reduction rolling (reducing), the entire diameter of the seam both sides 12 is reduced by the reduction rolling. Even if the pitch of the recesses 15 is extended, the pitch after the extension is 1/2 that of the form I (see FIG. 2). Therefore, the form IIA (see FIG. 4) is preferable because the specific difficulty of the virtual parallel lines 13 due to the increase in the pitch is reduced as compared with the case of the form I (see FIG. 2).

  As a method for manufacturing an electric resistance welded steel pipe according to the present invention, in an electric resistance welded pipe manufacturing method similar to that illustrated in FIG. 3, as shown in FIG. 5 and FIG. After the bead cutting 6 or the inner and outer bead cuttings 6 and 7, before the tube body 4 is cut to a predetermined length by a pipe cutting machine (not shown), the rolling tool 20 is pushed to the pipe outer surface side of the both side portions 12 of the seam. A method (referred to as method M1) in which a plurality of concave portions 15 are formed on two virtual parallel lines 13 sandwiching the seam portion 5 in the middle on the outer surface side of the pipe is mentioned. As the rolling tool 20, for example, a knurling tool (which is a process for forming a non-slip jagged shape on the surface of an object having a round surface) is suitable.

In the method M1, the bending or flattening of the tube body 4 is remarkably reduced as compared with the conventional method A in which the rolling tool is directly pressed against the outer surface side of the seam portion, and the cutting tool used for the inner surface bead cutting 7 and the inner surface of the tube are reduced. There is no excessive interference.
In addition, as a method for manufacturing an electric resistance welded steel pipe according to the present invention, an electric resistance welded pipe manufacturing method similar to that illustrated in FIG. After stripping the steel strip 1 from the coiled state, before rolling the width of the steel strip 1 by the roll forming 2 (on the entry side of the roll forming 2), both ends in the width direction of the steel strip 1 are placed on the pipe outer surface side. The steel strip thickness is composed of a gear-shaped roll 22 disposed on the side of the steel strip (in this example, the lower surface) and a flat roll 24 disposed on the side of the steel strip (in this example, the upper surface). By pressing in the direction, the concave portion 15 (see FIG. 1) is formed on the steel strip surface side (the lower surface side in this example) at both ends of the steel strip width direction, which becomes the pipe outer surface side of the seam both side portions 12 (see FIG. 1). 1 to 3) may be used (the method M2).

  In the method M2, at the stage where the steel strip 1 is flat, on the side of the steel strip on the pipe outer surface side (the lower surface side in this example) of the portions that become the seam both side portions 12 at both ends in the width direction, Since the indentation 30 which becomes the said recessed part 15 is formed, the gear-shaped roll 22 and the flat roll 24 do not have an installation space installation with the downstream roll forming 2, the electric-welding welding 3, and the outer surface bead cutting 6, and can be installed. There is an advantage that it is easy.

  As an example of the present invention, an ERW steel pipe having an outer diameter of 60.5 mm and a wall thickness of 4.0 mm was manufactured by the method M2. The indentation 30 applied on the entry side of the roll forming 2 is the pipe outer surface side of the seam both side portions 12 (the base material portion 16) at which the pipe circumferential direction angle θ is θ = ± 10 ° at the stage of pipe forming. Thus, a plurality of concave portions 15 arranged on two virtual parallel lines 13 sandwiching the seam portion 5 in the middle are formed. The indentation 30 has the same row pitch = 5 mm, one maximum dimension in plan view = 0.70 mm, depth = 0.30 mm, and one of the two rows is the other It was made to come to the position of 1/2 of the pitch of the line. These dimensions and arrangement were not changed even when the indentation 30 became the recess 15.

The manufactured ERW steel pipe can visually detect the recess 15, can specify the two virtual parallel lines 13 in which the plurality of recesses 15 are arranged, and seams the intermediate position between the specified two virtual parallel lines 13. It can be recognized that the portion 5 passes, and the seam portion 5 can be easily identified.
In addition, a 1 m long test tube collected from the manufactured ERW steel pipe was subjected to a heat treatment at 680 ° C. and a pipe extension treatment at an elongation rate of 26%. Could be identified.

The manufactured ERW pipe is subjected to ultrasonic flaw detection of the entire cross section of the seam part by MP-UT in the downstream inspection process, and the concave part 15 not interfering with the seam part 5 is erroneously detected as a flaw. No, the flaw detection accuracy of the ultrasonic flaw detection did not deteriorate.
As a comparative example, an electric resistance welded steel pipe having the same size as the example was experimentally manufactured by the conventional method A. The ERW steel pipe of the comparative example was able to identify the seam part from the visual detection of the concavo-convex treatment part at any stage after the heat treatment and after the pipe extension as it was, but in the downstream inspection process, the seam part by the MP-UT When the ultrasonic inspection of the entire cross section was performed, the unevenness processing part interfering with the seam part was erroneously detected as a flaw, and the flaw detection accuracy of the ultrasonic flaw was significantly deteriorated.

1 Band Steel 2 Roll Forming 3 ERW Welding 4 Tube (ERW Steel Tube)
DESCRIPTION OF SYMBOLS 5 Seam part 6 Outer surface bead cutting 7 Inner surface bead cutting 10 Pipe shaft 11 ERW welding heat-affected part 12 Seam both sides 13 Virtual parallel line 15 Recess 16 Base material part 20 Rolling tool 22 Gear-shaped roll 24 Flat roll 30 Indentation

Claims (3)

In an ERW steel pipe having a seam portion, which is a joint portion by ERW welding, a plurality of concave portions arranged on two virtual parallel lines sandwiching the seam portion in the middle on the pipe outer surface side are formed on both sides of the following seam. ERW steel pipe features.
The both sides of the seam mean that the pipe circumferential direction angle θ, in which one direction of bi-directional rotation around the tube axis of the tube body is 0 ° and the other direction is positive and the other direction is positive, The angle Φ defining the region is Φ = 45 °, and the region on the positive and negative sides of the angle range where −Φ ≦ θ ≦ Φ overlaps the base material portion of the tubular body. While continuously feeding the steel strip, the width of the steel strip is rounded by roll forming, and both ends of the rounded width are joined by electric resistance welding to form a tube, and the seam portion which is the joint portion by electric resistance welding is formed. In the method of manufacturing an electric resistance steel pipe for cutting and removing the bead on the pipe outer surface side or further on the pipe inner surface side,
After removing the bead on the pipe outer surface side or further on the pipe inner surface side of the seam part,
A rolling tool is pressed against the pipe outer surface side of both sides of the seam according to claim 1 to form a plurality of concave portions arranged on two virtual parallel lines sandwiching the seam portion in the middle on the pipe outer surface side. A method for manufacturing an electric resistance welded steel pipe. While continuously feeding the steel strip, the width of the steel strip is rounded by roll forming, and both ends of the rounded width are joined by electric resistance welding to form a tube, and the seam portion which is the joint portion by electric resistance welding is formed. In the method of manufacturing an electric resistance steel pipe for cutting and removing the bead on the pipe outer surface side or further on the pipe inner surface side,
Before rolling the width of the steel strip by roll forming, both ends of the steel strip in the width direction are arranged on the side of the steel strip on the side of the steel strip and the gear-shaped roll arranged on the side of the steel strip on the side of the pipe outer surface. By pressing in the strip thickness direction with a flat roll
The indentation which becomes the recessed part of Claim 1 is formed in the steel strip surface side of the both ends of a steel strip width direction which becomes the pipe | tube outer surface side of the seam both sides of Claim 1 characterized by the above-mentioned. Steel pipe manufacturing method.

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