JPS60187424A - Manufacture of tube having closed an end - Google Patents

Abstract

PURPOSE:To utilize the bottom of a bottomed material tube as it is and to improve its yield by providing a bottom thickness adjusting device on the upper edge of an outer die for containing a billet. CONSTITUTION:A billet is contained in an outer die 5, and a liner 6 for adjusting bottom thickness is provided in the upper part of the billet and outer mold 5. Under this condition, a mandrel 7 is thrusted in by a vertical hydraulic press. The bottom thickness of a material 4b to be pierced is adjusted by the bottom thickness adjusting liner 6. A hollow cylindrical material 4b thus obtained is hot reduced and a bottomed material tube is obtained. By this way, a tube having closed an end and having uniform mechanical strength as a whole is manufactured.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for manufacturing a one-end closed tube.

More specifically, the present invention relates to a method of manufacturing a one-end closed tube suitable for manufacturing pressure vessels, etc. using the Erhardt tube manufacturing method.

BACKGROUND OF THE INVENTION Generally, a pressure vessel is manufactured by joining two separately manufactured end plates 2 to both ends of a hollow cylindrical main body 1 by welding or the like, as shown in the attached FIG. 1. However, pressure vessels are usually used to fill, store, and transport gases, liquefied gases, etc. under high pressure conditions, and the interior is vacuumed before being filled with the above gases to prevent contamination with impurities. Therefore, it is necessary to have sufficient mechanical strength to withstand these harsh conditions such as high pressure or high vacuum, and to be free from defects.

In order to provide such mechanical strength, the above welding must be performed under strict control, and after welding, heat treatment to remove residual strain in the welded area, that is, strain relief annealing treatment, is generally required. mechanical strength inspection process is required.

Therefore, as shown in Fig. 1, when using a hollow cylindrical main body 1 and end plate 2, it is necessary to join them at least two places by welding or the like in order to create one pressure vessel. However, it is desirable to reduce the number of welded parts as much as possible.

Therefore, it is extremely important in this field to develop new technology that reduces the number of welded parts as much as possible, maintains sufficient mechanical strength, and reduces the number of required processes such as post-weld heat treatment and inspection. That's true.

Purpose of the Invention The purpose of the present invention is to provide a method for manufacturing a one-end closed tube that minimizes the number of welded parts and is suitable for manufacturing pressure vessels that are subjected to severe conditions such as high pressure and high vacuum. be.

Structure of the Invention In view of the above-mentioned current state of pressure vessel manufacturing methods, the present inventor has developed an appropriate method for manufacturing two bottomed blank tubes obtained by the Erhardt pipe manufacturing method in order to simplify the manufacturing of such pressure vessels. After the treatment, it was found that it would be better to join by welding or the like, and the present invention was completed.

That is, the present invention is suitable for manufacturing pressure vessels, etc.
The present invention provides a method for manufacturing an end-closed tube, which involves forming a hollow cylindrical material with a bottom having a predetermined bottom thickness by the Erhardt drilling method, and hot pressing the obtained hollow cylindrical material with a bottom. Cut it out to make a base tube of the required length,
The bottom part of the hollow cylindrical material with a bottom or the base pipe with a bottom is subjected to forging or rolling treatment.

In general, the hollow cylindrical material with a bottom obtained by the Erhardt drilling method has a low forging ratio of the surface layer and the bottom (approximately 2 at most).Furthermore, this material is hot-punched by the Bushbench method to a predetermined length. Even when it comes to a base pipe with a bottom, what is forged at this time is the surface layer of the base pipe, and the bottom part is still left with a low forging ratio.Therefore, when manufacturing pressure-resistant sealed containers such as pressure vessels, conventional methods are used. In this method, the bottom part with a low forging ratio was cut off and only the hollow cylindrical part was used.

Therefore, in the present invention, when drilling a steel billet using the Erhardt drilling method, by arranging a bottom thickness adjustment means such as a bottom thickness adjustment liner on the upper edge of the outer mold for storing the steel billet, a hollow cylinder with a bottom is formed. The bottom of the shape material is made thicker than before,
The above-mentioned drawbacks are solved by hot-punching this and subjecting the bottom of the bottomed hollow cylindrical material or bottomed blank tube to grinding, forging, rolling, etc.

In the method for manufacturing a one-end closed pipe of the present invention, when an ingot is used as the steel billet, grinding of the inner surface of the bottom and forging or rolling of the bottom are required in the post-treatment. This is because during the Erhardt drilling and subsequent hot punching using the Butschbench method, the head segregation and center porosity of the ingot remain concentrated on the inner surface of the bottom of the base tube, and these must be removed by grinding.

On the other hand, grinding is not necessary when using billets and blooms that have been subjected to rolling treatment after the head of the ingot, which already contains such segregation and center porosity, is cut off and removed.

In this way, the method of the present invention makes it possible to use the bottom part of the base pipe made by the Erhardt pipe manufacturing method, which was cut and removed due to poor strength in the conventional method, by appropriately treating it according to the method described above. Then,
Manufacturing yields are significantly improved.

The above-mentioned forging or rolling treatment of the bottom of the bottomed pipe is as follows:
There are methods of spinning the inner and outer surfaces of the bottom part or forging them, and furthermore, hard small balls may be shot. This forging or rolling treatment of the bottom portion can be performed at any time of the hollow cylindrical material with a bottom after drilling or the base tube with a bottom after punching.

In order to manufacture a pressure vessel similar to that shown in FIG. 1 using single-end closed tubes manufactured by the method of the present invention, the open ends of two single-end closed tubes are butt welded, and the welded portion is post-heat-treated. do. Next, the welded portion is inspected by radiographic inspection such as X-ray or T-ray, ultrasonic inspection, or eddy current inspection.

It goes without saying that the one-end closed tube manufactured by the method of the present invention can be used not only for manufacturing pressure vessels but also for other purposes.

EXAMPLES Hereinafter, the method for manufacturing a one-end closed tube of the present invention will be described by way of examples with reference to the accompanying drawings.

FIG. 2 is a schematic diagram of a method for producing a hollow cylindrical material with a bottom by drilling a steel piece with an Erhard.

As shown in FIG. 2(a), the steel piece 4a is housed in the outer mold 5. This steel piece 4a may be an ingot, a bloom, or a billet. The cross section of the steel piece 4a and the cross section of the accommodating portion of the outer mold are designed such that when the steel piece 4a has a square cross section, the diagonal length thereof and the diameter of the cylindrical accommodating portion of the outer mold 5 are approximately equal. . Further, the accommodating portion of the outer die 5 is tapered as shown in the figure, making it easy to take out the material to be drilled after drilling.

Next, as shown in FIG. 2(b), a bottom thickness adjusting liner 6 is placed on top of the steel piece 4a and the outer mold, and in this state, a mandrel 7 is pushed in by a vertical hydraulic press (not shown). The bottom thickness of the perforated material 4b can be adjusted by the thickness of the bottom thickness adjusting liner 6.

This material to be drilled, that is, the hollow cylindrical material 4b with a bottom, has its outer surface and bottom processed only at a forging ratio of about 2 in the above-described drilling operation.

The hollow cylindrical material 4b with a bottom thus obtained is hot-pressed as shown in FIG. FIG. 3(a) is a schematic diagram of the hot punching process, and shows a hollow cylindrical material 4b with a bottom.
Insert the mandrel 8 into the hole and punch it out with the die 9. This method itself is a well-known method and will not be described in detail, but the size of the steel slab 4a and the drilling and punching steps are designed so that the bottomed blank tube 4c has a predetermined thickness and length through this hot punching. It goes without saying that By this hot punching, a bottomed blank tube 4G shown in FIG. 3(b) is obtained. In the hot punching step, the wall of the cylindrical portion of the bottomed blank tube 4c is thinned and subjected to significant processing, but the bottom portion is not processed at all.

When the steel piece 4a is an ingot, the segregation and porosity of the ingot head are caused by the bottomed hollow cylindrical material 4 as described above.
h, so it is preferable to cool the bottomed blank tube after hot punching, cold grind it, and then subject it to forging or rolling treatment.

When the steel billet 4a is a billet or a bloom, the forging or rolling of the inner and outer surfaces of the bottom part may be performed at any time before or after hot punching. For example, base tube 4c with bottom
When the length is long, the hollow cylindrical material with bottom 4 before hot stamping
Although the above-mentioned treatment may be applied to the bottom of the tube 4c, it is advantageous to perform the above-mentioned treatment after hot punching when the length of the bottomed blank tube 4c is shorter than the inner diameter.

It goes without saying that the base tube 4c obtained in this manner may be subjected to a refining process such as correction of uneven thickness.

FIG. 4 is a schematic cross-sectional view of a pressure vessel 10 manufactured by butt welding two one-end closed tubes 4c manufactured by the method of the present invention detailed above according to an embodiment. The abutting portion of the one-end closed tube 4c is shown by a dotted line, and it is important to perform welding with a large penetration depth so that this portion 11 is welded. Such welding methods include high-grade welding methods such as TIG welding and MIG welding, as well as a combination of these methods under sufficient control.

The thus welded parts are subjected to a post-heat treatment to remove thermal stress as is known in the art, and are further inspected by X-ray, T-ray, ultrasonic or eddy current testing to obtain a pressure vessel product.

Effects of the Invention The present invention processes the bottom of a bottomed raw pipe obtained by the Erhardt pipe manufacturing method to produce a one-end closed pipe having a uniform forging ratio as a whole, that is, a uniform mechanical strength as a whole. It was extremely successful.

0 If the one-end closed tube manufactured according to the present invention is used, for example, when manufacturing a pressure vessel, the conventionally used end plate is not required, the number of welding points is reduced, and the number of manufactured units is significantly reduced.

Furthermore, according to the method of the present invention, conventionally cut as a defective part,
Since the bottom of the discarded base tube can be used, the tube manufacturing yield can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing welding locations of a pressure vessel according to the prior art. FIG. 2 shows the process of drilling a steel billet according to the present invention, and FIG.
Figure (I)) shows the state of drilling with a mandrel. Fig. 3(a) is a schematic diagram of the hot punching process of a hollow cylindrical blank tube with a bottom obtained by Erhardt drilling, and Fig. 3(b) shows a cross section of the obtained blank tube with a bottom. . FIG. 4 is a schematic cross-sectional view of a pressure vessel manufactured according to the present invention in which two one-end closed base tubes are butt welded. (Main reference numbers) 4a: Steel piece, 4h: Hollow cylindrical material with bottom, 4C: Base pipe with bottom, 4d: One end closed pipe, 5: Outer mold, 6: Bottom thickness adjustment liner, 7: For drilling Mandrel, 8: Mandrel for punching, 9: Die, 10: Pressure vessel, ll: Welded portion Patent applicant Sumitomo Metal Industries Co., Ltd. Representative Patent attorney Masahiko Arai 2 Σ

Claims (3)

[Claims] (1) A steel piece is housed in an outer mold, a bottom thickness adjusting means is placed on the outer mold, the steel piece is perforated with an Erhardt hole, and a hollow cylindrical material with an eave having a predetermined bottom thickness is formed. The hollow cylindrical material with an eave is hot-pressed into a blank tube with an eave of the required length, and the bottom of the hollow cylindrical material with an eave or the base tube with an eave is subjected to forging or rolling treatment. 1
A method for producing an end-occluded tube. (2) The method for manufacturing a one-end closed pipe according to claim 1, wherein the steel piece is an ingot, and the inner surface of the bottom of the eave-equipped raw pipe is ground. (3) The method for manufacturing a one-end closed pipe according to claim 1, wherein the steel piece is a bloom or a billet.