JP5380780B2 - UOE steel pipe expansion method, pipe expansion head, pipe expansion machine main body and pipe expansion device - Google Patents

Description

The present invention relates to a UOE steel pipe mechanical pipe expanding method , a pipe expanding head, a pipe expanding machine body, and a pipe expanding apparatus.

  The manufacturing process of a welded steel pipe by the UOE method is roughly as follows: a C press process for obtaining a C press formed body by subjecting a width direction side end portion of a thick steel plate, which is a material of the steel pipe, to a C press formed body, and the obtained C press forming A U-press process in which the central part in the width direction of the body is pressed and bent to form a U-press molded body, an O-press process in which the U-press molded body is molded into an O-shaped section by forming an O-shaped cross section, and It consists of a welding process for obtaining a welded pipe by welding from the inner and outer surfaces, and a pipe expanding process.

  Among the above processes, the pipe expansion process is a process aimed at giving a predetermined strain to the welded pipe from the inner surface and finishing it so as to have a predetermined size and roundness, and is used for line pipes. Steel pipes are required to have a particularly high roundness, for example, a tolerance of 5.0 mm or less. However, the UOE steel pipe has a straight welded part on the side, and when the welded part is cooled, complicated strain and internal stress are generated. As is done, when the pipe is expanded from the pipe end toward the center of the pipe by a certain length, there is a problem that the pipe end of the steel pipe becomes elliptical.

  In order to solve such a problem, in Patent Documents 1 and 2, when expanding a UOE steel pipe with a mechanical pipe expansion facility, the pipe expansion starts from the center in the longitudinal direction of the steel pipe and is sequentially expanded toward both ends of the steel pipe. Finally, a means for expanding the pipe end is disclosed.

Japanese Patent Application No. 3-93936 Japanese Patent Application No. 3-155421

  However, when adopting the means of starting the pipe expansion from the longitudinal center of the steel pipe and finally expanding the pipe end as described above, the side surface of the steel pipe after the pipe expansion is pushed perpendicularly to the longitudinal direction of the steel pipe. There is a problem that marks are generated. Therefore, the means disclosed in Patent Documents 1 and 2 have not yet been put into practical use, and are not only forced to perform cold correction after pipe expansion, but also demands for the roundness of the pipe end of the consumer. In severe cases, there is a problem in that yield decreases due to poor roundness.

  When the present invention adopts a means of starting the expansion from the longitudinal center of the steel pipe and finally expanding the end of the pipe, a push rod mark perpendicular to the longitudinal direction of the steel pipe is formed on the side surface of the expanded steel pipe. The purpose is to solve the problem of the occurrence of the problem, reduce the number of cold tube straightening steps after the expansion, and improve the product yield.

  The present inventor considers the cause of the push mark generated when the UOE steel pipe is expanded, and among the tools used in the pipe expansion process, the shape of the die mounted on the outermost part of the pipe expansion head is directed toward the pipe end. Thus, the present invention has been completed with the knowledge that generation of the push mark can be prevented by providing a specific range of gradient.

In the method of expanding the UOE steel pipe according to the present invention, when the UOE steel pipe is expanded by the mechanical expansion equipment, the expansion path is started from the center in the longitudinal direction of the steel pipe, and the expansion path is sequentially repeated toward both ends of the steel pipe, and finally the pipe is expanded. In performing the tube expansion pass to the end portion, a tapered portion that satisfies the conditions of the following expressions (1) and (2) is formed on the tube end side of the tube expansion portion formed by each tube expansion pass.
A ≧ D × 0.009 (1)
B ≦ 5.5% (2)
Where D: inner diameter of the material to be expanded, A: level difference of the taper portion, B: taper amount

  In the above-mentioned invention, it is desirable to form tapered portions that satisfy the conditions of the above formulas (1) and (2) on both sides of the expanded pipe portion by the first expanded pipe pass performed on the central portion in the longitudinal direction of the steel pipe.

  The method of expanding the UOE steel pipe includes a cone, a jaw, and a die. The UOE steel pipe is of a type that expands the die attached to the jaw by pushing and expanding the jaw by moving the cone in the axial direction. Implemented by utilizing a mechanical pipe expanding head for a UOE steel pipe in which a taper portion is formed at at least one end of the die to satisfy the conditions of the above formulas (1) and (2). can do.

The UOE steel pipe mechanical pipe expanding head may be formed with taper portions that satisfy the conditions of the expressions (1) and (2) at both ends of the die. Furthermore, the mechanical pipe expander main body of UOE steel pipe can have these pipe expansion heads. The mechanical expansion device for a UOE steel pipe according to the present invention includes a main body of a pipe expander composed of a main cylinder, a horn and a pipe expansion head, and a mechanical pipe expansion facility for a UOE steel pipe in which the main body of the pipe expander is arranged. The tube expansion device main body is arranged as a set of two groups in total, and at least one of the tube expansion device main bodies may be tapered at both ends of the die of the tube expansion head. . At this time, out of the main body of the expansion machine arranged as a set of the above two units, one unit is tapered at both ends of the die, and the other unit is tapered only at the tube end side of the steel pipe. It is preferable that the part is formed.
In the method of expanding the UOE steel pipe according to the present invention, when expanding the UOE steel pipe with the mechanical pipe expanding device, the pipe expansion path is started from the center in the longitudinal direction of the steel pipe, and the pipe expansion path is sequentially repeated toward both ends of the steel pipe. In performing the tube expansion pass to the end, at least when performing the first tube expansion, a die having tapered portions on both ends is expanded.

  According to the present invention, even if the means of starting the expansion from the center in the longitudinal direction of the steel pipe and finally expanding the end of the pipe is adopted, a push rod mark perpendicular to the longitudinal direction of the steel pipe is generated on the side surface of the expanded steel pipe. Nothing will happen. As a result, it is possible to easily manufacture a UOE steel pipe having a high roundness at the pipe end, and it is possible to reduce the number of cold pipe straightening steps after the pipe expansion and improve the product yield.

As shown in FIG. 1, the UOE steel pipe mechanical pipe expansion equipment to which the present invention is applied includes a pipe expander body 4 comprising a main cylinder 1, a horn 2, and a pipe expansion head 3, and a pipe 5 is fixed to the pipe expander body 4 at a fixed length. An axial infeed 6 to be fed and a cross field 7 for conveying the steel pipe 5 in a direction orthogonal to the axial infeed 6 are configured. As shown in FIG. 2, the expansion head 3 has a cone 12 connected to the main cylinder 1 by a draw bar 11 and is pulled in the axial direction by a hydraulic pipe 13 so that the jaw 14 is expanded by the wedge action of the cone 12 and the jaw 14. Thereby, the die 15 attached to the outer side of the jaw 14 in accordance with the inner diameter of the steel pipe pushes the steel pipe 5 apart.

  Also in this invention, the said pipe expander main body 4 is arrange | positioned as one set each on the right and left of the steel pipe 5, and a total of two sets, and the pipe expansion process which expands the steel pipe 5 half length with each pipe expander is employ | adopted. At that time, in the present invention, first, as shown in FIG. 3, the pipe expansion path is started from the longitudinal center portion 21 of the steel pipe 5. That is, firstly, a pipe expansion part 23 is formed in the steel pipe central part 21 by the first pass of the pipe expansion process, and then the pipe expansion process toward the right side of the steel pipe 5 using the pipe expansion machine body 5 arranged on one side of the steel pipe 5. The second pass is performed to form the expanded portion 24. This operation is repeated until the tube end portion 22 is reached. The same process is performed on the left half of the steel pipe 5 and the pipe is expanded to the left pipe end 25.

In this invention, in performing the said pipe expansion process, the taper part 26 formed in the pipe end side of the pipe expansion part formed by each pipe expansion pass shall satisfy | fill the conditions of following (1) Formula and (2) Formula. .
A ≧ D × 0.009 (1)
B ≦ 5.5% (2)
Here, D: inner diameter of the material to be expanded, A: level difference of the taper portion, B: taper amount.

The shape of the tapered portion at the time of tube expansion substantially matches the shape of the die 15. Here, the die 15 is configured by combining segments having the shapes shown in FIGS. 5A and 5B (see FIG. 2). The step A is determined according to the inner diameter D of the pipe material, then the curvature radius r ₁ on the outer surface side of the segment is determined in consideration of the expansion allowance, and the curvature radius r ₂ on the inner surface side is further determined by the following equation (3): Finally, the length L of the tapered portion 17 may be determined so as to satisfy the following expression (4).
A = r ₁ −r ₂ (3)
B = A / L (4)

Step A is A ≧ D × 0.009 (1)
The reason is that when the step A is less than D × 0.009 , wrinkles are generated on the inner surface of the pipe material to be expanded.

On the other hand, the taper amount B is set to B ≦ 5.5% (2)
This is because, when the taper amount B exceeds 5.5%, bamboo knot-like convex wrinkles occur at the connecting portion between the pitches in the tube expansion process.

  Using the tube expansion head 3 having the die 15 that satisfies the above parameters, the tube expansion path is started from the longitudinal central portion 21 of the steel pipe 5, and the tube expansion path is sequentially repeated toward both ends of the steel tube, and finally the tube end By performing the pipe expansion pass for the portions 22 and 25, a UOE steel pipe having a high roundness at the pipe end can be manufactured.

  At that time, it is desirable that the die 15 has tapered portions 17 and 18 that satisfy the above parameters at both ends of the die 15 as shown in FIG. 4 at least when the first pass of the tube expansion process is performed. Thereby, the pipe expansion process can be advanced without seeing the generation of the push mark due to a rapid step from the center of the steel pipe to the pipe end. In addition, the pipe expansion head provided with the taper part at both ends may be only one of the pipe expansion machine main bodies 4 provided on the left and right sides of the steel pipe 5, and the other one is as shown in FIG. Only a taper part can be provided.

Material: APIX60, outer diameter: 762.0 mm, thickness: 12.7 mm, length: 12,200 mm UOE steel pipe was subjected to mechanical pipe expansion with a pipe expansion ratio of 1.2%. The expansion results are shown in Table 1. As shown in Table 1, when satisfying the conditions of the present invention, without defects occurs, it was possible to carry out the expansion tube process smoothly.

Note: Inner diameter D = 762-12.7 × 2 = 736.6 mm
    D × 0.009 = 6.63mm

It is a side view of the mechanical pipe expansion equipment of the UOE steel pipe to which the present invention is applied. It is the (a) front view and (b) side view of the mechanical pipe expander of a UOE steel pipe. It is explanatory drawing of the pipe expansion process by this invention. It is sectional drawing of the segment of die | dye used for this invention. It is explanatory drawing of the parameter of a segment.

Explanation of symbols

1: Main cylinder
2: Horn
3: Tube expansion head
4: Expander main unit
5: Steel pipe
6: Axial infeed
7: Cross field
11: Drawbar
12: Corn
13: Hydraulic piping
14: Joe
15: Die
16: Parallel part (of die)
17: Taper
21: Central part (of steel pipe)
22: Pipe end
23: Tube expansion section
24: Expansion section
25: Pipe end

Claims (6)

When expanding the UOE steel pipe with mechanical expansion equipment, start the expansion path from the longitudinal center of the steel pipe, repeat the expansion path toward the both ends of the steel pipe, and finally perform the expansion path to the end of the pipe. A method of expanding a UOE steel pipe, characterized in that a tapered portion that satisfies the conditions of the following formulas (1) and (2) is formed on the pipe end side of a pipe expansion section formed by a pipe expansion path.
A ≧ D × 0.009 (1)
B ≦ 5.5% (2)
Where D: inner diameter of the material to be expanded, A: level difference of the taper portion, B: taper amount   2. The UOE according to claim 1, wherein a tapered portion that satisfies the conditions of the expressions (1) and (2) is formed on both sides of the expanded portion by an initial expansion path performed with respect to the central portion in the longitudinal direction of the steel pipe. Steel pipe expansion method. In a mechanical expansion head of a UOE steel pipe of a type consisting of a cone, a jaw and a die, which expands the jaw by moving the cone in the axial direction, thereby expanding the diameter of the die attached to the jaw.
Said die of at least one of the following to the end (1) and (2) heads for mechanical pipe expansion UOE steel pipe, wherein a tapered portion is formed for satisfying the:
Record
A ≧ D × 0.009 (1)
B ≦ 5.5% (2)
Here, D: inner diameter of the material to be expanded, A: level difference of the taper portion, B: taper amount.   The head for mechanical expansion of a UOE steel pipe according to claim 3, wherein tapered portions for satisfying the conditions of the expressions (1) and (2) are formed at both ends of the die.   A mechanical pipe expander main body for UOE steel pipe, to which the head for mechanical pipe expansion according to claim 3 or 4 is mounted. In the pipe expansion machine main body consisting of the main cylinder, horn and pipe expansion head, and the mechanical pipe expansion equipment for UOE steel pipe formed by arranging the pipe expansion machine main body,
The main body of the pipe expander is arranged with one set on each side of the steel pipe to be expanded, a total of two sets, and at least one of the pipe expander main bodies has the pipe expansion head according to claim 3 or 4. A mechanical pipe expansion facility for UOE steel pipes, which is mounted.

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