JPH0338009B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a processing method for forming the end of a raw pipe into a hemispherical shape when manufacturing various gas cylinders, accumulators, etc.

Conventionally, cylinders such as those mentioned above were generally forged,
It was manufactured using methods such as casting and cutting. However, in this case, it takes time to manufacture, and it is difficult to make long pieces, and it is also difficult to make thin pieces, resulting in poor productivity and high costs.

On the other hand, a spinning method is known as a processing method for forming an end portion of metal or the like into a hemispherical shape.
By carrying out this processing method hot, it is possible to seal the end of the metal tube into a hemispherical shape. However, in practice, by performing the above processing hot, oxides are drawn into the center of the hemisphere, that is, the part where the ends of the raw pipes gather and are joined, and a sound joint is not formed in that part. Therefore, it has not been possible to obtain a product that can be used as a pressure-resistant member.

This invention solves this problem by
The purpose is to make it possible to easily manufacture and provide products such as metal tube gas cylinders and accurators at low cost.

Therefore, when forming the end of a metal tube into a hemispherical shape by hot spinning,
After the end of the raw tube is first spun into a hemispherical shape, a hole is drilled in the center to remove the oxide intervention part where the end surfaces of the raw tube meet, and then the spinning process is further performed. The gist of this invention is a hemispherical processing method characterized by sealingly joining the perforated portions.

The metal tube mentioned above is generally made of aluminum or its alloy, or a cold forged product of iron, etc.
Extrusion molded products etc. are used.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

First, as shown in Fig. 1, the end of the metal tube 1 whose end is to be processed into a hemispherical shape is clamped and attached to the chuck 2 of the hot spinning machine, and the end to be processed is Preheat to the specified temperature using a burner, etc. Then, the raw pipe 1 is rotated as shown by the arrow A, and the forming roller 3 is moved forward and reciprocated in the directions of the arrows B and C while pressing against the circumferential surface of the pipe end, as shown in FIG. The hemispherical part 4 is formed by gradually constricting the tube end.

The above-mentioned hemispherical processing method is a known hot spinning processing method, and when a cold forged product made of A6351 alloy with a diameter of 76 mm is used as the base tube 1, the preheating temperature is set to 250°C, and the base tube 1 is By applying a rotation of 750 rpm and setting the reciprocating speed of the forming roller 3 in the direction of arrow C to approximately 10 times/min,
During this processing, the temperature of the processed part of the raw pipe 1 is reduced by frictional heat.
The desired hemispherical part 4 could be molded by maintaining the temperature at 300 to 400°C.

When the tube ends are closed and joined by the above-described spinning process, as shown in FIG. This results in a rolled up joint 5. Naturally, such a joint portion 5 containing oxide 6 is not healthy and has poor joint strength.

Therefore, in the present invention, after the above-mentioned first spinning process, as shown in FIG. Remove portion 5, the oxide intervening portion. At this time, in order to prevent the inner circumferential surface of the perforated part 8 and its vicinity from being oxidized again and producing oxides, an inert gas G such as argon gas is sprayed from the nozzle 9 toward the perforated part. It is preferable that the part be kept in an inert gas atmosphere.

Immediately after the above-mentioned drilling is performed, a second spinning process is performed again, and the circumferential surface of the above-mentioned perforated part 8 is brought in from the surroundings, and the top of the hemispherical part 4 is hermetically joined as shown in FIG. . During this second spinning process, it is also preferable to use the nozzle 9 in the same manner as above.
Needless to say, it is necessary to spray more inert gas G toward the workpiece to prevent the oxide from being drawn into the joint again.

As described above, the present invention can form a sound joint at the top of the hemisphere without oxide intervention. Therefore, the joint can have sufficient strength and perfect airtightness, and can be safely used in pressure vessels such as gas cylinders by having a pipe body formed from the hemispherical part. It can be done. Furthermore, compared to the conventional methods of manufacturing pressure-resistant components such as forging and casting, it is easier to manufacture long, large, and thin-walled components, and it is also easier to manufacture them. There are significant advantages in that it allows for significant cost reductions.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention in the order of steps. Figure 1 is a partially crushed side view of a metal raw tube set in a spinning machine, and Figure 2 shows the raw metal tube during the first spinning process. FIG. 3 is a cross-sectional view of the main part showing the state of the tube being deformed and formed, FIG. 3 is a cross-sectional view of the state at the time of drilling, and FIG. 4 is a cross-sectional view of the state after the second spinning process has been performed. DESCRIPTION OF SYMBOLS 1...Metal raw pipe, 3...Forming roller, 4...Semispherical part, 5...Joining part, 6...Oxide, 7...
Drill, 8...Drilling part, 9...Nozzle, G...Inert gas.

Claims (1)

[Scope of Claims] 1. When forming the end of a metal tube into a hemispherical shape by hot spinning, the end of the metal tube is first spun into a hemispherical shape, and then a hole is formed in the center of the tube. A method for forming a hemispherical shape, characterized in that the oxide intervening portion where the end surfaces of the raw tube meet are removed by doing so, and then a spinning process is further performed to seal the perforated portion. 2. The hemispherical processing method according to claim 1, wherein the drilling process and the subsequent spinning process are performed while the processed part is maintained in an inert gas atmosphere.