JP3250466B2 - Expansion dies for mechanical expansion machines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an expansion die used for a mechanical expansion machine installed in a UOE steel pipe production line, and more particularly to an expansion die suitable for processing a pipe having a size outside a range where pipe production is possible. It is.

[0002]

2. Description of the Related Art A steel pipe expander has a function of removing residual stress of a UO tube at the time of pressing or welding and shaping the tube to a final size. The steel pipe expander is provided with a pipe expanding die that can be expanded and contracted in the radial direction, is inserted from one end of the raw pipe, and is sequentially moved to the other end of the raw pipe while expanding the pipe.

[0003] Conventional pipe expanding dies consist of a plurality of circumferentially divided die segments, all of which are made of tool steel.

In the process of manufacturing a UOE steel pipe, a normal-size O-press is performed by inserting a stop liner 13a between an upper die segment 11 and a lower die segment 12, as shown in FIG. A method of shaping the pipe 10 into a perfect circle is adopted.

As shown in FIG. 1 (B), insert liners for O-press upper die segment 11 and lower die segment 12 which match the outer diameter of the raw tubes are used for the raw tubes having different sizes. 15 (in the drawing, two sheets are overlapped) and a method is adopted for molding. For this reason, in an O-press raw tube of a UOE steel pipe of a normal size, the dies (46 inches, 48
Inches, 54 inches, 56 inches, etc.) and insert liners.

On the other hand, in the case of an intermediate tube (for example, 40.3 inches, 41 inches, etc.) in which the size of the tube deviates from the above-mentioned normal size, as shown in FIG.
The upper die segment 11 and the lower die segment 12 under the size are used, and the stop liner 13b is thicker than the normal stop liner between the segments.
And O-press processing is performed.

However, when a thick stop liner is used, the shape of the tube after O-pressing tends to be extremely elliptical as shown in FIG. 1 (C). Required.

[0008] A tube expanding machine used for a tube expanding process for improving the shape and dimensional accuracy such as roundness and outer diameter includes:
There are mechanical expansion and hydraulic expansion. For expanding a large-diameter raw pipe such as a UOE steel pipe, a mechanical expanding machine that can easily expand a thick-walled, high-strength material compared to a hydraulic method is employed. This mechanical expander has a main cylinder, horn,
It consists of three parts: an expander main body consisting of an expander die, an axial infeed for feeding a steel pipe into the expander by a fixed length, and a cross feed for conveying a raw pipe in a walking beam manner.

As shown in FIG. 2, a conventional expansion die of this mechanical expansion machine has a cone 2 connected to a main cylinder (not shown) by a draw bar 1.
The jaw 3 is spread by the wedge action of the cone 2 and the jaw 3 by being pulled in the axial direction by hydraulic pressure, and the die segment 4 arranged outside the jaw pushes and expands the raw tube 10 to expand to a predetermined size. Mechanism. Reference numeral 5 denotes a drawbar fixing bolt, and reference numeral 6 denotes a die stopper.

[0010] In the case of the above-mentioned medium-sized tube, the shape of the tube before expansion has a large vertical elliptic shape, and there is a problem that the vertical ellipse remains after expansion in ordinary expansion.

In Japanese Patent Laid-Open Publication No. Hei 7-290170, as shown in FIG.
A "mechanical tube expander head" has been proposed in which a roundness correction liner 7 is inserted between the two and the outer diameter of the tube expansion die is elliptical.

[0012]

The mechanical expander head provided with the straightening liner and formed in an elliptical shape has a great effect on roundness correction, but has the following problems.

The location at which the roundness straightening liner is mounted is between the segment and the jaw. For this mounting, 1) removal of the segment, 2) mounting of the straightening liner to the segment, and 3) mounting of the segment. It requires a series of work of mounting, and cannot be directly mounted or removed. Further, since all the tools of the pipe expander such as the segments are made of tool steel, it is necessary to use a crane, and the straightening liners must be attached one by one. Furthermore, the pipe expansion process is a bottleneck step in the flow of the entire factory, and the downtime of the pipe expander for installing the straightening liner has a great influence on the flow of the entire factory.

The present invention solves the above-mentioned problems of the prior art, is effective for correcting a large longitudinal ellipse before expansion, and can ensure roundness after expansion even in an intermediate size. It is another object of the present invention to provide a tube expanding die for a mechanical tube expanding machine, which can adjust in a very short time.

[0015]

According to the present invention, there is provided a pipe expander die for a mechanical pipe expander. In the steel pipe expander for expanding and shaping a steel pipe base tube by means of a pipe expander capable of expanding the diameter, each of the soybeans constituting the pipe expander die is provided. The above-mentioned problem is solved by a means characterized in that the thicknesses of the segments are made different so that the outer diameter of the expansion die is elliptical.

It is preferable that the die segment comprises a thick segment having the same thickness, a thick segment having a taper, a thin segment having the same thickness, and a thin segment having a taper. The segment taper is provided at the portion of the segment that contacts the jaws that expand and contract the outer diameter of the expansion die.

It is preferable that the die segment is formed of a lightweight crystalline thermoplastic resin.

[0018]

In order to prevent the die marks of the expanding dies for the expanding machine from being formed on the inner surface of the raw tube at the time of expanding the tubes, the present inventors have formed and used a die segment with a crystalline thermoplastic resin. As a result, a great effect was obtained (Japanese Patent Application No. 7-54436). The die segment formed of the crystalline thermoplastic resin is very light, and the setup time can be greatly reduced.

The present invention is an application of the lightweight feature of the crystalline thermoplastic resin to the head disclosed in Japanese Patent Application Laid-Open No. 7-290170.

An expansion die for a mechanical expander, comprising a cone connected to the main cylinder by a draw bar, a jaw slidably disposed on the outer periphery of the cone, and a die segment attached to the outside of the jaw, is axially moved by the draw bar. Due to the wedge action of the cone and the jaw drawn on the pipe, the expanding dies are spread uniformly in the radial direction and expanded. When the expansion die of the present invention is used, since the outer diameter of the expansion die has an elliptical shape, it is possible to expand the longitudinally elliptical elemental tube before expansion in a lateral direction, so that the roundness after expansion is increased. Can be secured even in an intermediate size.

[0021] The dice of the expanding dice for the mechanical expanding machine.
The segments having the same thickness, thick and thin, and thin and thick with a tapered contact surface with the jaw are formed by making the outer diameter of the expansion die elliptical. The reason for making the shape and tapering is to eliminate the height difference between the segments. That is, if there is a height difference between the segments, a scratch is formed on the inner surface of the raw pipe during the expansion, and in order to prevent this, a tapered segment is used.

By using the expansion die of the present invention, the outer shape of the expansion die can be formed into an elliptical shape, so that good roundness can be obtained not only at the end of the pipe but also at the center of the pipe. Can be The roundness of the central part of the raw pipe is extremely important, especially for UOE steel pipes. That is, since the UOE steel pipe has one welding seam, residual stress due to welding heat input concentrates at one location in the circumferential direction at the pipe end. For this reason, when the tube after expansion is cut at the center, the roundness of the cut portion is highly likely to be extremely deteriorated as compared with the cut surface, and the cut may be out of specification. Therefore, it is necessary to ensure better roundness at the center of the pipe.

By using a crystalline thermoplastic resin as the material of the segment, the replacement time of the expanding dies due to the change of the outer diameter and the wall thickness of the dies is greatly reduced as compared with the conventional expanding dies made of tool steel. It is possible to do. In the case of tool steel, one segment weighs around 100kg,
The use of a crane was indispensable for replacement, and it was necessary to remove one by one. However, in the case of crystalline thermoplastic resin, since one segment is about 10 kg, attachment and detachment can be easily performed without using a crane. Therefore, the replacement time can be greatly reduced as compared with the case of the die segment made of tool steel using a crane.

[0024]

4 (B) is a longitudinal sectional side view showing an example of the structure of an expansion die for a mechanical expander according to the present invention, FIG. 3 is a front view of FIG. 4 (B), and FIG. 5 is a die in the expansion die. -It is a perspective view which expands and shows the segment 8,
(A) is a thick segment 8-1 having the same thickness, (B) is a thick segment 8-2 having a taper, (C) is a thin segment 8-3 having a taper, and (D) is a segment having a same thickness. Each of the thin segments 8-4 is shown. Here, a description will be given by taking, as an example, an expanding die for an expanding machine having a structure in which the segment 8 is divided into twelve.

The die segment 8 has thin segments 8-4 having the same thickness as shown in FIG. 5D at positions corresponding to the upper and lower sides of the cone 2, and FIG. Thick segment 8-1 having the same thickness shown in A)
5B and 5C at positions corresponding to other oblique sides.
The thick segment 8-2 having a taper and the thin segment 8-3 having a taper are used so that no step is formed on the outer surface of the segment.

In the production of a medium-sized steel pipe, when the expanding die having the above-described structure is used for expanding a raw pipe having a large vertical ellipse after O-pressing, the raw pipe having the vertical ellipse is laterally expanded by the expanding die. Since the pipe is greatly expanded, roundness after expansion can be secured. In addition, since there is no step on the outer surface of the tube expanding die, there is no abrasion on the tube inner surface during the tube expanding.

Since the amount of plastic deformation due to the pipe expanding process depends on the size (wall thickness t / outer diameter D) of the raw tube, the correction of the roundness can be changed by changing the thickness of the segment. FIG. 6 is data obtained by experimentally determining the relationship among various tube sizes (t / D), segment thickness differences, and roundness correction amounts. From this data, it is understood that the effect of roundness correction can be obtained for all sizes by using segments having different thicknesses. Further, by changing the mounting position of the segment, it is possible to cope with roundness defects in various types of directions.

[0028]

[Embodiment 1] The target size is 40.3 inches in outer diameter (diameter 1).
024 mm), wall thickness 29.1 mm, length 12,200 m
A UOE steel pipe (grade API × 65) of m is expanded using a pipe expansion die with segments having different thicknesses shown in FIGS. 3 to 5 and a conventional pipe expansion die (constant segment thickness) shown in FIG. FIG. 7 shows the roundness in the case of the above. In this embodiment, the roundness target value (maximum outer diameter−minimum outer diameter)
Is set to 5.0 mm or less, and the thicknesses t1, t2, and t3 of the used segments (see FIG. 5) are each 8.0 m.
m, 6.0 mm, 4.0 mm (segment thickness difference =
4.0 mm).

[0029] When the pipe expansion process was performed using the conventional pipe expansion dies (with no thickness difference), a non-standard steel pipe was generated. As can be seen from the data in FIG. 7, the roundness (vertical diameter−horizontal diameter) afterwards could be changed to the minus side by about 4 mm on average.

FIG. 9 shows the time required for removing the 40-inch die segment (made of tool steel) from the jaw, attaching the straightening liner to the die segment and attaching it to the jaw again, and the crystallinity for the 40-inch. FIG. 6 compares the time taken to remove a segment made of a thermoplastic resin and to attach a segment having a thickness difference as shown in FIG. As is apparent from this figure, the segment made of the crystalline thermoplastic resin is very light and does not require a crane for replacement, so that the time can be greatly reduced.

[0031]

Embodiment 2 The target size is 29.0 inches in outer diameter (diameter 7).
37.5 mm), wall thickness 28.2 mm, length 12,200
In the same manner as in Example 1, the expansion processing of a UOE steel pipe (grade API × 65) with a thickness of 0.2 mm was performed using the expansion die having the segments having different thicknesses shown in FIGS. 3 to 5 and the conventional expansion die (segment) illustrated in FIG. FIG. 8 shows the roundness of the tube when the thickness is constant (constant thickness), and Table 1 shows the roundness passing rate at the pipe end and the roundness (length-width) at the center of the pipe. In this embodiment, the roundness target value (maximum outer diameter−minimum outer diameter) is 7.3 mm or less (1
% Outer diameter), and the thicknesses t1, t of the used segments.
2, t3 (see FIG. 5) are 11.5 mm and 11
mm, 10.5 mm (Segment thickness difference = 1.0 m
m).

As is clear from the results shown in FIG. 8 and Table 1, when the segment having the thickness difference of the present invention was used, the roundness was improved at both the pipe end and the pipe center.

[0033]

As described above, according to the expansion die for a mechanical expansion machine of the present invention, the following effects can be obtained. (1) The roundness of an intermediate-sized steel pipe having an extremely elliptical vertical tube shape after O-pressing can be secured over the entire length. (2) The segments are very lightweight, can be replaced in a short time, and do not affect the flow of the entire process. (3) Since the entire length can be worked from the pipe end to the center at the same expansion ratio, a steel pipe having a small fluid resistance can be obtained. (4) The amount of roundness correction can be changed by changing the segment thickness difference. (5) By changing the attachment position of the segment, it is possible to cope with roundness defects in various directions. (6) The manufacturable steel pipe size can be increased without increasing the number of dies.

[0034]

[Table 1]

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates an O-press working method in a manufacturing process of a UOE steel pipe, (A) is a normal O-press working method, (B) is an O-press working method using an insert liner, and (C) is The O-press working method for an intermediate-sized steel pipe deviating from the normal size will be described.

FIG. 2 is a longitudinal sectional view showing a structural example of a conventional die for a mechanical expander.

FIG. 3 is a front view showing a structural example of a die for a mechanical expander according to the present invention.

FIG. 4 is a longitudinal sectional view similar to FIG. 2 for an expanding die;
(A) shows another conventional example, and (B) shows an embodiment of the present invention.

FIG. 5 is an enlarged perspective view showing a segment having a thickness difference in the tube expanding die shown in FIG. 4 (B),
(A) shows a thick segment with the same thickness, (B) shows a thick segment with a taper, (C) shows a thin segment with a taper, and (D) shows a thin segment with the same thickness.

FIG. 6 is data obtained by experimentally obtaining a relationship between various tube sizes (t / D), segment thickness differences, and roundness correction amounts.

FIG. 7 is a diagram showing roundness in Example 1 of the present invention in comparison with a conventional example.

FIG. 8 is a diagram showing roundness in a second embodiment of the present invention in comparison with a conventional example.

FIG. 9 is a diagram showing a segment exchange time in Example 1 of the present invention in comparison with a case where a roundness correction liner is used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Drawbar 2 ... Cone 3 ... Jaw 4 ... Die segment 5 ... Drawbar fixing bolt 6 ... Dice stopper 7 ... Roundness correction liner 8 ... Dice・ Segment 10 ・ ・ Base tube

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ identification code FI C08L 77/00 C08L 77/00 (58) Field surveyed (Int.Cl. ⁷ , DB name) B21D 39/20 B21C 37/08 B21D 3/14 B21D 37/01 C08L 61/06 C08L 77/00

Claims (3)

(57) [Claims] 1. A steel pipe expanding machine for expanding and shaping a steel pipe base tube by an expandable die capable of expanding in diameter, wherein a difference is provided between the thickness of each die segment constituting the expandable die, and An expansion dice for a mechanical expander, wherein the outer diameter is configured to be elliptical. 2. A die segment comprising a thick segment having the same thickness, a thick segment having a taper, a thin segment having the same thickness, and a thin segment having a taper. The expansion die for a mechanical expansion machine according to claim 1. 3. The expansion die for a mechanical expansion machine according to claim 1, wherein said die segment is formed of a lightweight crystalline thermoplastic resin.