Claims
- 1. A forging method for a hollow article having a peripheral groove, comprising the steps of:
- a first step of disposing a columnar material into a first stepped die with a cavity having large and small internal diameter portions and extruding one end portion of said material with a first punch in a direction opposite to an advancing direction of said first punch to thereby form a first blind hole in the center portion of said material;
- a second step of deepening said first blind hole in a second stepped die with a cavity having large and small internal diameter portions and a stepped portion until the hole reaches the proximity of the stepped portion, and extruding the other end portion of said material into the inside of said small internal diameter portion of said cavity with a second punch previously extended thereinto to thereby simultaneously form stepped material having a large outer diameter portion and a small outer diameter portion with a stepped portion therebetween and a second blind hole at said other end portion thereof while leaving a blind portion between said first and second blind holes;
- a third step of fitting said first and second blind holes to third punches while exposing in an unsupported manner the outer periphery of the small outer diameter portion of said stepped material from a third die and pressurizing, by means of a sleeve, only an end face portion of said small outer diameter portion formed with said second blind hole to expand said small outer diameter portion of said stepped material toward the outer periphery to form an expanded portion, thereby forming a peripheral groove between said expanded portion and the stepped portion of said stepped material; and
- a fourth step of punching out said blind portion between said first and second blind holes of said stepped material to cause said first and second blind holes to communicate with each other.
- 2. The method according to claim 1, wherein in said third step, in pressurizing, by means of said sleeve, only said end face portion of small outer diameter portion of said material formed with said second blind hole, an inner wall of said second blind hole is restricted by one of said third punches.
- 3. The method according to claim 1, wherein in said third step, in pressurizing, by means of said sleeve, only said end face portion of small outer diameter portion of said material formed with said second blind hole, an inner wall of said second blind hole is restricted by one of said third punches, and an outer surface of said end face portion of said small diameter portion is restricted by said sleeve with a cavity which produces said expanded portion and corresponding to the shape of a forging article.
- 4. The method according to claim 1, wherein said stepped material put through said second step is turned up side down and is then disposed in said third die in said third step.
Priority Claims (1)
Number |
Date |
Country |
Kind |
62-181233 |
Jul 1987 |
JPX |
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RELATED APPLICATION
This application is a Continuation-in-Part of application Ser. No. 07/223,151 filed July 22, 1988, now abandoned.
US Referenced Citations (3)
Foreign Referenced Citations (4)
Number |
Date |
Country |
201326 |
Dec 1955 |
AUX |
1527474 |
Mar 1970 |
DEX |
97838 |
Jul 1980 |
JPX |
145326 |
Aug 1983 |
JPX |
Non-Patent Literature Citations (2)
Entry |
Industrieanzeiger, No. 12, p. 22, Mar. 12, 1982. |
American Machinist, p. 139, July 20, 1953. |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
223151 |
Jul 1988 |
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