JPS6257414B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method of manufacturing a bottomed cylindrical part, such as a cup-shaped or cap-shaped part, by forward extrusion.

(Prior art) In general, in forward extrusion processing of bottomed cylindrical parts, as shown in Fig. 1, the outer diameter of the blank 1 before processing is made smaller than the inner diameter of the die 2, and the blank 1 is
The mutual dimensions are adjusted so that there is a gap between the die 2 and the die 2. Blank 1 into the insertion port of this die 2
is inserted, the blank 1 is pushed into the die 2 by the punch 3, the blank 1 is pressed against the counter punch 4, and plastic working is performed. Here, the die 2 is supported in a vertically floating manner, and when the blank 1 is pushed into the die 2 by the punch 3, the die 2 also descends together with the blank 1, thereby forming a small mold. Processing can now be performed using a load. After molding, the molded product 6 is taken out of the die by the knockout sleeve 5.

Therefore, as shown in Fig. 2, when the blank 1 is pushed into the die 2 by the punch 3, the blank 1 is moved to one side of the die 2 by the gap C and is not located at the center of the die 2. becomes. As a result, as shown in Fig. 3, the counter punch 4 is bent in the direction of the gap (in the direction indicated by arrow 7) at the beginning of extrusion of the blank 1, and thereafter the extrusion process continues with the counter punch 4 tilted. will be carried out. As a result, as shown in Fig. 4, the center of the inner diameter of the molded product 6 deviates from the center of the outer diameter, resulting in poor coaxiality, uneven thickness, uneven extrusion height, and uneven end face inclination. A large cylindrical product 6 with a bottom is produced.

(Object of the Invention) The present invention is intended to improve the above-mentioned drawbacks regarding the extrusion processing of cylindrical products with a bottom.When a blank before extrusion is pushed into a die, the blank is fitted in a state with no gap between the blank and the die. By aligning the blanks and ensuring that the blanks are coaxial with the die, the present invention provides a method for manufacturing highly accurate bottomed cylindrical parts with good coaxiality of the inner and outer diameters, uniform extrusion height, and little inclination of the end face. .

(Structure of the Invention) The present invention is characterized by a step of inserting a blank into a die that is supported so as to be floating in the vertical direction and has a tapered inner surface whose diameter is enlarged toward a blank insertion opening, and a step of pushing the blank with a punch to a position where there is no gap between the punch and the die; a step of subsequently lowering the punch and the die together to press the blank against a counter punch to form a cylinder with a bottom; The method consists of a step of taking out the molded product from the die using a knockout sleeve.

(Function) Since the present invention is constructed as described above, there is no relative gap between the blank and the die, so the blank does not lean toward one side of the die, and the blank can be reliably provided coaxially with the die. Even if the blank is pressed against the counter punch, bending of the counter punch and uneven thickness of the molded product are less likely to occur.

(Example) Hereinafter, one example of the present invention will be explained with reference to the drawings.

As shown in FIG. 5, the hole of the die 8 has a tapered surface 8c that decreases in diameter as it goes deeper from the insertion opening 8a of the blank 1 until it reaches a cylindrical portion 8b with a diameter not larger than the diameter of the blank 1. Provide a blank insert for forming. When the blank 1 is inserted through this insertion port 8a and the blank 1 is pushed into the die 8 by the punch 3, the tapered surface 8c of the die 8 is inserted into the blank 1.
The blank 1 and the die 8 fit together at a portion having the same diameter. Since there is no gap in this fitting part 9,
It is ensured that the die 8 and the blank 1 are set coaxially (as shown in the figure on the left side of the center line in the figure).

After that, the punch 3 further advances and the die 8 moves together with the blank 1, but the blank 1 is struck by the counter punch 4 and is extruded with the outer periphery and one end surface being restrained by the die 8 and the punch 3 (Fig. (shown by the line to the right of the center line).

When the bottomed cylinder is formed, the punch 3 is moved to the die 8.
The knockout sleeve 5 pushes the molded product 10 out of the die 8.

The bottomed cylinder processed in this way has a bending of the counter punch 7 caused by the gap between the blank 1 and the die 8 during the initial stage of extrusion in which the blank 1 is plastically worked between the punch 3 and the die 8 and the counter punch 4. It is possible to obtain a highly accurate product with good coaxiality of the inner and outer diameters after molding, uniform extrusion height, and little inclination of the end face.

Thanks to improved processing accuracy, it can be applied not only to manufacturing bottomed cylinders but also to manufacturing short hollow cylinders. For example, as shown in FIG. 6, a cylinder 11 with a bottom is first formed as shown in a, then a bottom plate portion 11a is punched out as shown in b, and then c is
A hollow cylindrical product 12 with good coaxiality of inner and outer diameters can be obtained.

(Effects of the Invention) In the method for manufacturing a bottomed cylinder of the present invention as described above, the blank does not shift to one side of the die,
The blank can be reliably coaxial with the die,
This prevents bending of the counter punch and uneven thickness of the molded product. This improves product yield and contributes to cost reduction.

[Brief explanation of the drawing]

Fig. 1 is an explanatory cross-sectional view of a manufacturing method according to a conventional method, Fig. 2 is an enlarged explanatory cross-sectional view showing the deviation of a material according to a conventional method, and Fig. 3 is an enlarged explanatory cross-sectional view showing the bending of a counter punch according to a conventional method. FIG. 4 is a cross-sectional view showing the bending of a concave portion of a processed product according to the conventional method, FIG. 5 is an explanatory cross-sectional view showing the manufacturing method according to the present invention, and FIG. 6 is an explanatory cross-sectional view showing an example of application of the present invention. 1...Blank, 3...Punch, 4...Counter punch, 5...Knockout sleeve, 88...
...Die, 8a...Blank insertion opening, 8b...Cylindrical part of die, 9...Fitting part, 10... Molded product.

Claims (1)

[Claims] 1. Inserting a blank into a die that is supported so as to be floating in the vertical direction and has a tapered inner surface whose diameter is expanded toward a blank insertion port;
A step of pushing the blank with a punch to a position where there is no gap between the blank and the die, and then lowering the punch and the die together to press the blank against a counter punch to form a cylinder with a bottom. 1. A method for producing a bottomed cylindrical part, comprising the steps of: and then taking out the molded product from the die using a knock-out sleeve.