JPH01162537A - Manufacture of bomb - Google Patents

Abstract

PURPOSE:To obtain a bomb of high accuracy in its high yield and low cost by forming a hollow by the cold pre-rear part extrusion of a blank, forming a bottomed pipe by a cold rear part extrusion by placing a solid lubricant in the hollow and drawing by a hot treatment the opening end only by the die for necking of high temp. CONSTITUTION:A pre-rear part extrusion is executed on an Al or Al alloy blank 1 to form a hollow 1a on the end face of the blank 1. A solid lubricant 2 is placed on the hollow 1a to obtain a bottomed pipe 3 by cold rear part extruding. A mouthpiece part is then formed by one time forward extrusion by sticking a lubricant after heating by using the die 4 for necking. An Al or Al alloy made gas bomb can thus be obtd. at low cost and with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a seamless metal gas container (cylinder). In particular, the present invention relates to a method of manufacturing a seamless cylinder made of aluminum or an aluminum alloy by a forging method.

(Prior Art) Conventionally, a steel gas container has been made of a pipe, and the bottom surface has been formed by forge welding by high-frequency heating of the end surface of the pipe. Similarly, the mouthpiece was formed by high-frequency heating the end face and then pressing down (Mannesmann method).

However, aluminum gas cylinders used for medical purposes cannot be made by forge welding pipes.

For this reason, the following method is used.

First, the blank is heated to about 450℃, and using a carbon-based lubricant, hot backward extrusion processing (Erhardt drilling) is performed.
Obtain a bottomed tube. Next, by cutting,
After forming a bottomed tube of regular dimensions, an aluminum cylinder is manufactured by swaging or spinning the mouthpiece.

(Problems to be Solved by the Invention) However, in this method, the machining accuracy is poor, which increases the cutting cost when manufacturing the bottomed tube, and the material yield is poor. Furthermore, the working efficiency when molding the mouthpiece was poor, making the overall production cost high.

As a manufacturing method for aluminum cylinders that does not require Erhardt drilling, there is a method in which the bottom part and the mouth part are manufactured by cutting or forging separately, and these are welded by MIG, TIG, etc. to form a cylinder. However, this manufacturing method produces seams, resulting in insufficient reliability of the welded parts, which is a problem when used for high-pressure gas.

The purpose of the present invention is to solve the problems of the conventional method of manufacturing aluminum, miniram, or aluminum alloy cylinders, and to develop a method for manufacturing aluminum or aluminum alloy cylinders with high yield, low cost, and high precision. It is to provide.

(Means for solving the problem) In order to achieve the above-mentioned purpose, the present inventors have conducted repeated research,
I got the following idea.

Instead of hot backward extrusion when manufacturing bottomed tubes,
It is well known that cold backward extrusion can be used to produce bottomed tubes with good precision and no uneven thickness. However, the dimensions of the bottom tube for cylinders are L (hole depth) / D (
Hole diameter) ≧5 is required. Therefore, if the blank is extruded backwards only by lubricating the entire surface during cold working, seizure will occur on the inner surface due to lack of lubrication, making it impossible to manufacture a bottomed tube. However, by first forming a recess in the blank by preforming, filling it with solid lubricant, and then performing backward extrusion, a bottomed tube with L/D≧5 can be manufactured with high precision without seizure.

Next, when forming the mouth part, after heating the mouth drawing die and applying lubricant, the bottomed tube is extruded forward without heating, and the temperature of the material in the mouth drawing part increases due to heat conduction from the die. The deformation resistance and extrusion pressure can be reduced. At this time, because the body has high buckling stress due to work hardening, it was found that it was possible to achieve a draw ratio of approximately 60% or more without causing buckling in one draw. . As a matter of course, the opening with a closing rate of 60% or less can be easily achieved by applying this method.

Thus, the gist of the present invention is that, in the production of aluminum or aluminum alloy cylinders, a recess is created in the blank by cold preliminary rear extrusion, a solid lubricant is placed in the recess, and then a cold rear extrusion is performed. Aluminum is extruded to form a bottomed tube, and the mouth end is formed by pressing the open end against a high-temperature mouth drawing die that has been heated and lubricated to hot squeeze only the open end. Or a method for manufacturing an aluminum alloy cylinder.

(Function) The process up to forming the bottomed tube and the process of drawing the mouth by forward extrusion processing (the process of forming the mouth part) will be explained separately.

Figure 1 +al~(dl shows each process of forming a bottomed tube.

Aluminum or aluminum alloy blank 1 (
In FIG. 1(a)), preliminary backward extrusion is performed to form a depression (recess) la on the end face of the blank l (FIG. 1(b)).

Next, after placing a solid lubricant (metallic soap, Bonda Lube (Nippon Parkerizing A1 registered trademark), Mo5t, etc.) 2 in the depression la (Fig. 1 (C)), the bottomed tube 3 is (Fig. 1 Fdl).

Note that if the blank 1 has high hardness, annealing is performed before backward extrusion.

In this manner, in the present invention, a depression is first formed in the blank and a solid lubricant is placed in the depression, so that sufficient lubricant is always supplied to the processing section during cold backward extrusion processing. Therefore, when manufacturing the bottomed tube, there is no risk of seizure occurring on the inner surface due to lack of lubricant. The amount of lubricant added is L
/D is 4-5, 60-80g/I, L/D is 5-5
In the case of No. 7, 80 to 200 g/rrr is desirable.

In this way, by the method shown in Figure 1 (al~+di), it is possible to easily manufacture a bottomed tube with an L/D of 5 or more without seizure on the inner surface. A vertical hydraulic press is more convenient due to its characteristics.The ratio of the wall thickness of the bottom tube to the outside diameter of the body is 0.04 to 0.08.
That's about it.

Danshu Plate Melon Bottom Process Using a mouth drawing die (press) 4, the mouth part is formed by forward extrusion processing (mouth drawing) (Fig. 1(e)).
.

The mouth diameter of the cylinder with standard dimensions shown in Figure 2 is only about 40% of the body outer diameter D0, and a mouth opening ratio of approximately 60% is required (the mouth opening ratio is (1-D/ Do) X 100 (
According to the research conducted by the present inventors, the maximum neck reduction rate possible in one cold extrusion is approximately 30%, and exceeding this value causes axial buckling in the body. .

Therefore, in order to obtain a cylinder with a large necking ratio, two methods can be considered: heating the opening end of the bottomed tube, and heating a necking die and heating the opening end of the bottoming tube by heat transfer from the die.

When the bottom tube itself is heated, aluminum has good heat conductivity, so a considerable area becomes softened by heating. As a result, axial buckling occurs at a portion slightly away from the portion processed by the die during extrusion, making extrusion impossible.

On the other hand, in the method of heating the die, only the part undergoing processing softens, and the extrusion pressure decreases. However, since other parts are not softened, buckling is less likely to occur, and extrusion with a mouth reduction rate of about 60% is possible with only one forward extrusion.

Therefore, in the present invention, the bottomed tube is not heated, but a mouth drawing die to which a lubricant is applied after heating is used to form the mouthpiece by one forward extrusion.

Possible methods for heating the die include heating with a burner and incorporating a heat transfer heater or high-frequency heating device into the die, but the method using a heat transfer heater is less expensive and has better workability. The heating temperature of the dice is desirably higher than the recrystallization temperature of the core material in order to reduce deformation resistance.

The bottomed tube is work-hardened by cold working and has a very high buckling stress, so it does not buckle and can be formed by one forward extrusion with a high drawing ratio.

(Example) An aluminum cylinder was manufactured by the method of the present invention with the specifications of each dimension as follows (Figure 2): Total length It
: 22h+m Base diameter D: 20v
an Outside diameter of the body DO: 50+u+ Inside diameter D+ of the body: 43o+m Body wall thickness t: 3.5Illra Mouth wall thickness t: 7 mm or more Shoulder radius of curvature R: 3 (1 mm) Next, regarding the manufacturing of the cylinder, the bottom The process up to tube formation and the process of forming the mouthpiece will be explained separately.

Diameter 50+am x Length 7 from aluminum material 6061
A 0mo+ blank is cut out, heated at 400° C. for 1 hour, and then air cooled and annealed. Thereafter, after lubrication using Alpond 3299 and Bonda Lube (both registered trademarks of Nippon Parkerizing), preliminary backward extrusion is performed using a hydraulic press to fill the recesses with a solid lubricant (eg, calcium stearate). This amount added is IQGglof. Next, by this backward extrusion, we created a material with excellent surface roughness.
A bottomed tube with L/D=5.3 with almost no eccentricity was manufactured. No burning was observed on the inner surface.

Dankura-Sato Solework Continuing, after applying lubricant to the mouth drawing die 4 which was heated to approximately 450℃ using a heat transfer heater, one forward extrusion was performed to form a mouth part with a diameter of 2. (Figure 1 (
e)). A carbon-based lubricant was used to lubricate the die. No buckling was observed in the body of the cylinder, and the product quality was good. Furthermore, no seizure was observed on the mouthpiece.

The wall thickness t8 near the mouth part needs to be about twice the cavity wall thickness t, but when a prototype was cut and measured for investigation, it was about 2.05 times, indicating a good thickness increase rate. Ta.

Note that the present invention is applicable to manufacturing cylinders not only of aluminum and aluminum alloys but also of various iron-based and copper-based materials.

(Effects of the Invention) According to the present invention, all processing, including the molding of the mouthpiece, is performed with high precision by the forging method, resulting in reduced yield, increased cost, and
There is no need to worry about deterioration of accuracy.

Therefore, according to the present invention, a gas cylinder made of aluminum or an aluminum alloy can be manufactured at low cost and with high precision.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing each step of cylinder manufacturing according to the present invention; and FIG. 2 is a cross-sectional view of the cylinder showing the specifications of the cylinder. 1: Blank 2; Solid lubricant 3 : Bottom tube 4: Mouth drawing die (press)

Claims (1)

[Claims] In the production of aluminum or aluminum alloy cylinders, the blank is subjected to cold preliminary backward extrusion to create a depression in the blank, a solid lubricant is placed in the depression, and then cold backward extrusion is performed to form a bottomed tube; A method for manufacturing an aluminum or aluminum alloy cylinder, characterized in that a cap portion is formed by pressing the open end against a high-temperature mouth drawing die that has been heated and then lubricated, and then hot-squeezing only the open end.