JPS61152310A - Edge preparation for automatic welding for pipe - Google Patents

Abstract

PURPOSE:To permit the edge preparation and the inner surface working with high precision and apply automatic welding by plastic-working inside the edge part to be welded of a pipe and forming the pipe edge part into nearly circular. CONSTITUTION:The inside of the edge part 2 of a pipe 1 is plastic-worked by a jack apparatus, etc. Therefore, the edge part 2 of the pipe 1 can be made nearly circular. By the edge 9 working and inner surface 10 of the pipe 1, the edge 9 having high precision can be obtained. Since, no dislocation nor gap is generated when the worked pipes 1 are butt-jointed, the automatic welding used for the pipe welding with high precision can be applied.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applicable to a relatively thin tube having a thickness of about 4 to 12+ mm and a diameter of 200 to 800 mm. The present invention relates to an automatic pipe welding groove processing method suitable for butt welding medium-diameter steel pipes.

[Conventional technology]

It has a relatively thin wall with a thickness of about 4 to 12 mm, and the diameter of the pipe is 20 mm.
0~800. As shown in Fig. 6, medium diameter steel pipes have poor circularity and have a cross-sectional shape that is distorted from the perfect circle indicated by the broken line, with a long diameter part (α) and a short diameter part (b ). When such a pipe is beveled for butt welding, as shown in Figure 7, the bevel at the long diameter part (,) has a sloped surface compared to the case of a perfectly circular pipe shown by the broken line. becomes longer, and as shown in FIG. 8, the groove at the short diameter portion (6) has a shorter inclined surface than in the case of a perfectly circular tube shown by the broken line.

When attempting to weld pipes with grooves processed in this way, if the longer diameter part (tx) and the shorter diameter part (6) are butted against each other as shown in Figure 9, the mismatch (d) will occur. , a gap (-) occurs and automatic welding is not possible, so manual TIG
Welding was done by welding.

[Problem that the invention seeks to solve]

Conventional butt welding of thin-walled medium-diameter pipes involves a large amount of weld metal to be welded, is inefficient because it is performed manually, and has the disadvantage of poor appearance of the welded part. To provide a groove processing method for automatic welding of pipes, which can obtain a groove with high precision so as to automate the butt welding of pipes with poor precision.

[Means for solving problems]

In the present invention, after plastically working the end of the pipe to be welded,
This is a method for automatically welding a groove in a pipe by processing the end portion into a circular shape.

[For production]

The end of the pipe to be welded no longer has a long diameter section, and is machined into a perfectly circular bevel.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the end (2) of the tube (1) to be welded is plastically worked toward the inside where the center line of the tube (1) is located.

When performing this plastic working, the working jack (3) shown in Fig. 2 is attached to the end (2) of the pipe (1) using the four-way jack (4) and the outer restraining ring (5). , mainly presses the long diameter part inward. In addition, in Figure 2, (6
) is the drive motor, (7) is the jack block fixing pin,
(8) is a circumferential drive ring.

By plastically working the end (2) of the tube (1) inward in this manner, the end of the tube (1) can be made into a nearly perfect circle as shown in FIG. As shown in FIG. 4, the tube (1) thus constructed has a groove (9), in which (1) indicates the tube and (2) the end.

By performing the machining of 1 and the inner surface (101), a highly accurate groove (9) can be obtained, and as shown in FIG.
When (1) is butted together, there will be no misalignment (d) or gap (g) as shown in Figure 9, and automatic welding, which is used for high-precision pipe welding, can be applied. can.

〔Effect of the invention〕

The present invention has the effect that the tube end becomes a perfect circle, improving the groove precision and making it easier to apply automatic welding.

[Brief explanation of drawings]

Figure 1 is a partial cross-sectional view of the end of the tube, which has been plastically worked on the inside.
Fig. 2 is a cross-sectional view of the plastically worked pipe, Fig. 3 is a front view of the plastically worked pipe, Fig. 4 is a cross-sectional view of the groove processed by the method of the present invention, and Fig. 5 is the Figure 6 is a front view of the medium diameter pipe, Figures 7 and 8 are cross-sectional views of the grooves processed by the conventional method,
FIG. 9 is a cross section 1 showing a state in which the grooves in FIGS. 7 and 8 are butted together.

Claims (1)

[Claims] 1) A method for automatically welding a bevel for a pipe, which comprises plastically working the end of the pipe to be welded inward, and then processing the end into a circular shape.