Title:
METHOD FOR MANUFACTURING CYLINDRICAL BODY HAVING DIFFERENT DIAMETERS BY COLD FORGING
Document Type and Number:
WIPO Patent Application WO/2017/090224
Kind Code:
A1
Abstract:
According to the present invention, when a molded body having a preliminary hole is cold forged to form a cylindrical body having different diameters through deep hole processing being performed on the preliminary hole so that the preliminary hole is formed into a large-diameter hole part, and then, through formation of a small-diameter hole part by punching of the bottom surface of the large-diameter hole part, a punch having a dowel at the center of the leading end surface is used for the deep hole processing so that internal flaws due to dead metal generated on the inner circumferential surface of a recess formed, by the dowel, in the bottom surface of the large-diameter hole part do not remain. The outer diameter D1 of a dowel 125d of a deep hole punch 120d is set to be smaller than the inner diameter D2 of a small-diameter hole part 21e that is to be formed by punching of the bottom surface 27d. Accordingly, internal flaws K generated on the inner circumferential surface 29d of a recess 28d formed, by the dowel 125d, in the bottom surface 27d of a large-diameter hole part 25d in a molded body having deep hole processing performed thereon are removed along with punching debris when the small-diameter hole part 21e is formed by punching.
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Inventors:
OCHIAI SATORU (JP)
Application Number:
PCT/JP2016/004549
Publication Date:
June 01, 2017
Filing Date:
October 12, 2016
Export Citation:
Assignee:
NGK SPARK PLUG CO (JP)
International Classes:
B21J5/06; B21K21/08; B21J5/10; B21J13/02
Domestic Patent References:
| WO2015056373A1 | 2015-04-23 |
Foreign References:
| JP2002011543A | 2002-01-15 | |||
| JP2000094080A | 2000-04-04 | |||
| JP2007278806A | 2007-10-25 | |||
| JP2007307601A | 2007-11-29 |
Attorney, Agent or Firm:
AOKI, Noboru et al. (JP)
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