JP2002178026A - Manufacturing method for uoe pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To freely manufacture a UOE pipe having an intermediate outside diameter of a millimeter(mm) size or the like without preparing new dies. SOLUTION: A first O-bending press is performed by use of an insert liner to be applied to the outside diameter of a pipe on the larger side for the intermediate outside diameter till a metal plate fills and is subjected to a prescribed compression and, next, after turning the pipe formed by pressing approximately 90 deg., the pipe is formed into the target intermediate outside diameter by applying the O-bending press again.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a production line for a UOE pipe in which the production outer diameter is determined step by step.
The present invention relates to a method of manufacturing a UOE pipe capable of manufacturing a UOE pipe having an intermediate size pipe diameter.

[0002]

2. Description of the Related Art UOE pipes are manufactured by pressing a plate material previously cut to a predetermined material length into a round shape, and joining opposite ends thereof. U which is a typical example of UOE pipe
A typical flow of the OE steel pipe manufacturing process will be described with reference to FIG.

[0003] A plate material cut to a predetermined material length (100) is firstly ground (110) and then subjected to an edge bending press (120).
), U-press (130) and O-press (140) to form a circle. Then, tack welding was performed (150).
Thereafter, the inner and outer surfaces of the butted end surfaces are welded (160).
Thereafter, the pipe is expanded using an expander or the like (170).
At the same time as having a predetermined pipe diameter, the pipe is formed so that the roundness is within the specified range. Finally, a hydraulic test (180) and inspection (19)
0) is performed and shipped as UOE steel pipe.

Normally, the outer diameter of a steel pipe for a line pipe used in a pipeline for transporting oil or natural gas is specified in inches of 2 inches, and the outer diameter is adjusted to the pipe diameter. An O-press is formed by laminating insert liners 3 corresponding to a 2-inch pitch. As a matter of course, in the above-described UOE steel pipe manufacturing process, the diameter of the pipe to be formed is stepwise. The insert liner will now be described in more detail. In the process of the O-press (140), as shown in FIG.
It is mounted inside 2a, 2b and adjusted so as to have an inner diameter corresponding to the outer diameter of the pipe to be molded.

[0005] The thickness of the insert liner is fixed,
By laminating insert liners prepared for each corresponding inner diameter, the manufacturing inner diameter can be changed only in stages. As described above, the O-press is a process before welding and pipe expansion, and the outer diameter of the pipe formed by the O-press is set to an outer diameter that allows for the expansion rate in the pipe expansion step.

[0006] As described above, in the production of UOE steel pipes that are manufactured stepwise in inch size, for example, the order of UOE steel pipes having an outer diameter of an intermediate size of millimeters (mm) is put in. May be necessary,
Conventionally, an insert liner suitable for the intermediate size is separately prepared and attached to an O-press to manufacture.

However, in this method, it is necessary to prepare an insert liner for every outer diameter of an intermediate size, and it takes time to change the insert liner. There was a problem that the production cost of the product pipes due to production and possession would lead to a decrease in productivity. Therefore, for example, in Japanese Patent Application Laid-Open No. 9-1234, on the assumption that the expansion rate is increased by performing the expansion in the subsequent expansion step a plurality of times,
It has been proposed that the target pipe diameter in the O-press is made one size smaller than the target size for molding, and that an existing insert liner is used.

In Japanese Patent Application Laid-Open No. 9-29339, one of the upper and lower molds is used as an existing mold, the other is newly made, and O-press is performed by changing the radius and the center position from each other to obtain a predetermined pipe diameter. Of UOE steel pipes. And by doing so, the mold cost is halved, and
According to the company, the setup time required for changing the mold can be greatly reduced.

[0009]

SUMMARY OF THE INVENTION
In the method disclosed in Japanese Patent Application Laid-Open No. 9-1234, it is necessary to add a pipe expansion step several times, and the pipe expansion ratio becomes too large, and there is a great possibility that the mechanical properties (particularly, elongation properties) of the UOE steel pipe are deteriorated. In addition, in the method disclosed in Japanese Patent Application Laid-Open No. 9-29339, although additional steps and problems of mechanical properties do not occur, it is necessary to newly manufacture a mold for one side, and the insert liner is used for setup change. The problem that time is required for the change remains.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it has been proposed to use a millimeter (m
m) An object of the present invention is to make it possible to freely manufacture a UOE pipe having an intermediate outer diameter such as a size.

[0011]

SUMMARY OF THE INVENTION According to the present invention, a plate material cut to a predetermined material length according to a manufacturing outer diameter is formed into a U-shape by a U press, and a mold and an insert corresponding to the mold are formed. It is formed in a pipe shape by an O-press whose outer diameter can be set stepwise by replacing the liner, and then the opposite ends of the formed plate are joined, and finally the pipe is expanded to set stepwise. Using a UOE pipe manufacturing facility for manufacturing a pipe having an outer diameter of
In manufacturing the OE pipe, the first O-press is performed on the intermediate outer diameter until the plate material is filled and receives a predetermined compression using an insert liner applied to the outer diameter of the pipe on the larger side. , Stands for its pressed and formed pipe
The above problem has been solved by a method of manufacturing a UOE pipe characterized in that after 90 ° rotation, an O-press is performed again to obtain a target intermediate outer diameter.

In the present invention, when the above-mentioned O-pressing is performed again, the spring back of the formed pipe is anticipated,
It is preferable that the pressing position of the mold of the O press is pressed to a position where the circumference between the upper and lower insert liners is deeper than the position where the circle of the predetermined material length is geometrically inscribed. Further, in the present invention, it is preferable that the pipe diameter set in a stepwise manner is set to an inch size, and the middle pipe diameter is a millimeter-sized pipe diameter.

[0013]

First, with reference to FIG. 4 (a), a description will be given of a conventional forming method in an O-press of an inch-size UOE steel pipe which has been conventionally performed. FIG. 4 (a)
Is a graph illustrating the transition of the horizontal and vertical pipe outer diameters in the forming process with an O-press during the manufacturing process of a UOE steel pipe having a product diameter of 32 inches, in a graph. Transition in the direction of the arrow.

As shown in the drawing, until the pipe to be molded fills the mold and insert liner of the O-press, the decrease in the vertical diameter is almost equal to the increase in the horizontal diameter. Also, during this time, the compression deformation of the entire pipe has not been received,
Only the shape of the plate changes. After that, when the plate material fills the mold and insert liner, the vertical diameter decreases according to the further press, but the horizontal diameter cannot increase, and the pipe is compressed in the circumferential direction as a whole. become.

[0015] The inventors of the present invention have described that the plate material is a mold,
Focusing on the fact that the shape of the pipe can be freely changed in the molding process until the inside of the insert liner is filled,
By utilizing this characteristic, it has been found that a UOE pipe having an outer diameter smaller than the manufacturing outer diameter set stepwise by the die and the insert liner to be used can be freely molded.

That is, in the present invention, the material length L of the plate material is set in advance to a length obtained by correcting the amount of compression and expansion based on the circumference of the UOE pipe to be manufactured. Is performed twice to obtain a predetermined circular pipe. Here, in the first O-press, a predetermined amount of compression is performed after over-molding to a flat shape, and then the over-molded and flattened pipe is rotated by about 90 °, and the second press is performed. An O press is performed to form a circle having a predetermined diameter.

By the way, in the second O-press, the press position of the O-press mold is set to a position where a circle having a circumference L is geometrically inscribed between the upper and lower insert liners in anticipation of the springback of the pipe after molding. It is preferred to press to a deeper position and overtighten. The springback component may be, for example, a unique value determined as a table value based on past experience for each product pipe outer diameter. One thing to note here is that, in a normal mold, for example, in the case of a 20-inch mold, the gap between the upper and lower molds is about 0.5 inch (12.7 mm). Since the back has a length of about 15 mm, the mold is in contact with the back and it is impossible to perform sufficient pressing.

Therefore, in the method of the present invention, FIG.
As shown in (a), it is essential to increase the gap between the upper and lower molds 2a and 2b in advance. That is, it is necessary to grind the end faces of the molds 2a and 2b in advance and to secure a sufficient grinding amount a. At this time, the insert liner 3 is ground in the same manner. In other words, it is important to ensure a sufficient gap between the upper and lower molds (including the insert liner) so that the O-press can be overtightened.

Then, the O-press was excessively tightened, and for example, as shown in FIG. 1 (b), the pipe was tightened and molded until the upper and lower molds contacted, and the lemon was cut into slices in the vertical direction. It is formed into such a flat shape, and predetermined compression is also performed. An example of transition of the pipe diameter in the vertical and horizontal directions in the forming by the method of the present invention will be described with reference to FIG.

In the method of the present invention, the mold is first tightened and pressed to the same position as in the prior art. At this stage, the plate material is filled in the mold (more precisely, in the insert liner). There is no problem, and even if the vertical diameter becomes the same value as the conventional one, the horizontal length remains small and the shape is elongated vertically.
Then, by further pressing and tightening, the pipe is formed into a flat pipe having a pipe diameter smaller than the die and a vertical diameter shorter than the horizontal diameter, and the die (including an insert liner). ) Is filled with the material and a predetermined compression is performed.
By doing so, it is possible to correct the undulation generated in the plate material due to the end bending or the bending in the U press.

Next, the formed pipe is rotated by about 90 °, and again O-pressed to be formed into a circular shape. To rotate the pipe by approximately 90 °, a turning roller that is installed in a lower mold (not shown) and that can be inserted through a molding surface is used. At this time, the press amount of the mold is set to be equal to the pipe outer diameter D ′ shown in the following equation (1) in anticipation of the increase in diameter due to the expansion.
Is set to a value corresponding to.

D ′ = D / (1 + E / 100) (1), where D: UOE pipe outer diameter (product pipe outer diameter), E:
Expansion rate (%). Here, as the vertical diameter corresponding to the pipe outer diameter D 'after the O-press, it is preferable to set the vertical diameter at the time of the O-press in consideration of the springback after the O-press. That is, if a predetermined amount is excessively pressed and tightened in anticipation of the springback amount, FIG.
As shown in FIG. 7 (b), the shape after O-pressing is closer to a perfect circle than in FIG. 7 (a), which does not allow for the springback amount. Remains of a slightly non-circular shape hardly occur, and the shape is close to a perfect circle.

By performing the molding as described above, a circular pipe having a vertical diameter and a horizontal diameter substantially equal can be formed. However, since the pipe is processed into a perfect circle in the subsequent expansion process, even if the elliptical shape is formed by the first O-press, there is no problem in transporting the pipe or correcting it in the final expansion process. Second, the step of forming into a circular shape, which is performed for the second time, may be unnecessary.

By employing the above-described method of the present invention, a UOE pipe of, for example, a millimeter (mm) size, in addition to a pipe outer diameter other than a normal size, for example, an inch size, is formed.
It is now possible to manufacture easily using the same equipment without having to make new molds and insert liners.

[0025]

[Embodiment] A sheet thickness of 25 by four kinds of forming methods including the method of the present invention
A UOE steel pipe having a mm and an outer diameter of 800 mm and a millimeter (mm) size was manufactured. The manufacturing conditions are shown below. (A) Comparative Example 1: An insert liner corresponding to an outer diameter of 800 mm is separately mounted on the upper mold and the lower mold of the O-press separately in advance. Then, the plate material cut to the initial material length in the case of manufacturing a UOE steel pipe having an outer diameter size of 800 mm is subjected to an O-press forming by the above-mentioned mold through an end bending press and a U press,
After welding, the pipe was expanded and finished into a UOE steel pipe with an outer diameter of 800 mm. (B) Comparative Example 2: UOE with outer diameter size of 30 inch (762 mm)
Plate material cut to the initial material length when manufacturing steel pipe,
Outer diameter 30inch (762mm) after end bending press and U press
O-press forming was performed using a corresponding existing mold, and after welding, pipe expansion was performed twice to finish a UOE steel pipe with an outer diameter of 800 mm. (C) Comparative Example 3: A plate material cut to an initial material length when manufacturing a UOE steel pipe having an outer diameter of 800 mm is adjusted through an end bending press and a U press so as to have the same circumference as the outer diameter of 800 mm. It was formed by an O-press combining an upper mold having an outer diameter of 32 inches (813 mm) and a new lower mold having a smaller diameter. After welding, the pipe was expanded and finished into a UOE steel pipe having an outer diameter of 800 mm. (D) Example of the present invention: A plate material cut to the initial material length in the case of manufacturing a UOE steel pipe having an outer diameter of 800 mm is subjected to an end bending press and a U press, and the existing upper and lower metal corresponding to an outer diameter of 32 inch (813 mm). The first press molding is performed by an O-press of the mold until it becomes a flat shape with a predetermined compression ratio. Then, the formed flat pipe is rotated by 90 °, and the O-press is performed again. And molded into a circular shape. And
After the next step, the tube was expanded after welding to make a UOE steel pipe with an outer diameter of 800 mm. In the O-press molding, the press is performed in consideration of the springback. In addition, the end surface of the mold of the O-press is ground in advance, and the gap between the molds is sufficiently secured so as to allow over-tightening in the example of the present invention.

In each of the above four cases,
The time required for molding, that is, the production time was compared. The result is shown in FIG. Here, in FIG. 5, the vertical axis represents the normal (when molding by the conventional method shown in FIG. 2).
The production time of each 32-inch UOE steel pipe is defined as a reference time (1), and the respective production time ratios are taken. Next, FIG.
Is a graph comparing the hardness after molding for the above four cases. In FIG. 6 also, the vertical axis indicates the respective hardness level ratios based on the hardness (1) of the UOE steel pipe made of the same material by a normal (conventional method shown in FIG. 2) method.

In FIG. 5, in Comparative Example 1, since it is necessary to mount the insert liner dedicated to the diameter on the upper and lower dies, it takes time to replace the insert liner. Therefore, especially, the processing time in the O press becomes long. Comparative Example 2
In such a case, the time for changing the mold is not particularly required, and the manufacturing time is increased by performing the final pipe expansion step twice. Further, in Comparative Example 3, it is necessary to mount the insert liner dedicated to the diameter on the lower die, and it takes time to replace the insert liner. Although the length is shorter than that of Comparative Example 1, the manufacturing time is greatly increased.

On the other hand, in the case of the example of the present invention, the time required for performing the 90 ° rotation of the formed pipe and performing the second O-press is longer than the time required for manufacturing a normal 32 inch size UOE steel pipe. However, it is possible to manufacture a UOE steel pipe having an intermediate outside diameter of millimeters (mm) without significantly reducing efficiency. Next, in the hardness comparison shown in FIG.
The hardness of Comparative Example 2 is significantly increased, and it is very difficult to satisfy the mechanical properties even from the UOE steel pipe product standard. In other cases, including the examples of the present invention, there is no particular problem in hardness.

As described above, in the example of the present invention, without preparing a special mold and insert liner,
It is possible to efficiently manufacture a UOE steel pipe having good mechanical properties.

[0030]

According to the present invention, it is possible to manufacture a UOE pipe of an intermediate size in which a mold and an insert liner are not prepared, and a millimeter (mm) can be manufactured without creating a new mold and insert liner. A UOE pipe having an intermediate outer diameter such as a size can be freely manufactured.

As a result, it is possible to reduce the cost required for manufacturing the mold and the insert liner, and to shorten the setup change time.

[Brief description of the drawings]

FIG. 1 is a schematic view of an O-press applied to the present invention.

FIG. 2 is a flowchart showing a manufacturing process of a UOE pipe.

FIG. 3 is a schematic diagram showing a state of an O press of a UOE pipe.

FIGS. 4A and 4B are graphs showing an example of transition of a vertical diameter and a horizontal diameter of a UOE pipe in an O press, wherein FIG. 4A shows a conventional case and FIG. 4B shows a case of the method of the present invention.

FIG. 5 is a graph showing a production time ratio of a UOE steel pipe in the present invention example and some comparative examples.

FIG. 6 is a graph showing a hardness level ratio of a UOE steel pipe in the present invention example and some comparative examples.

FIG. 7 is a schematic diagram for explaining a derivative embodiment of the present invention.

[Explanation of symbols]

 1 UOE pipe 2a (Upper) Mold 2b (Lower) Mold 2c, 2d Opposing end face 3 Insert liner

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Yamamoto 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture Inside the Chiba Works, Ltd. (72) Inventor Muneyoshi Murakami 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba F-term (reference) 4E028 CB06 CB08 4E063 AA01 BA09 BA10 BA11 BA12 CA02 CA03 KA10 KA15

Claims (2)

[Claims] 1. A plate material cut to a predetermined material length according to a manufacturing outer diameter is formed into a U-shape by a U press, and the outer diameter is stepped by exchanging a mold and an insert liner corresponding to the mold. Formed into a pipe shape with an O-press that can be set
By joining the opposing end portions of the formed plate material and finally expanding the pipe, the above stepwise setting was performed using a UOE pipe manufacturing facility for manufacturing a pipe having an outer diameter set stepwise. In manufacturing a UOE pipe having an intermediate outer diameter of the outer diameter, the first time the plate material is filled with the insert liner applied to the pipe outer diameter on the larger side to the intermediate outer diameter until it undergoes a predetermined compression. UOE, characterized in that the pressed and formed pipe is rotated by approximately 90 ° and then O-pressed again to obtain a target intermediate outer diameter.
Pipe manufacturing method. 2. When the O-press is performed again, the press position of the O-press mold is set in such a manner that the circumferential length between the upper and lower insert liners is equal to the predetermined material length in anticipation of the springback of the formed pipe. The method for manufacturing a UOE pipe according to claim 1, wherein the pressing is performed to a position deeper than a position where the circle is geometrically inscribed.