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Title:
MANUFACTURING METHOD OF PRIMARY METAL FITTING MOLDED ARTICLE FOR SPARK PLUG, MANUFACTURING METHOD OF PRIMARY METAL FITTING FOR SPARK PLUG, AND SPARK PLUG MANUFACTURING METHOD
Document Type and Number:
WIPO Patent Application WO/2015/056373
Kind Code:
A1
Abstract:
If the thread diameter of a primary metal fitting for a spark plug is the same, then even if the longitudinal position of the inward protruding annular portion, which is a second inside step portion, is different or the screw length is somewhat different, as long as the outer diameter of a tip-side annular portion provided at the screw tip, and the longitudinal dimension thereof, are the same, then the types of molds required for the formation of the tip-side annular portion can be reduced when forming a primary metal fitting molded article with cold forging. Prior to formation of a tip-side annular portion (32), a body being molded (30e), in which a second inside step portion (44) is formed, is loaded from the tip side into a mold (201f) having a tip-side annular portion forming part (205f, 206f); an annular tip-facing surface (243f) of a punch (240f) is pressed from behind into the inside of the body being molded (30e); the second inside step portion (44) is pressed by the annular tip-facing surface (243f); the tip portion of the molded body (30e) is pressed against a tip-side annular portion forming part (205f, 206f); and the tip-side annular portion (32) is pressed forwards to be extrusion-molded. Through this molding step, a primary metal fitting molded article (30f) is obtained.

Inventors:
OCHIAI SATORU (JP)
KARIYA MITSUNARI (JP)
Application Number:
PCT/JP2014/003585
Publication Date:
April 23, 2015
Filing Date:
July 07, 2014
Export Citation:
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Assignee:
NGK SPARK PLUG CO (JP)
International Classes:
B21K21/08; B21J5/06; H01T21/02
Domestic Patent References:
WO1994010731A11994-05-11
Foreign References:
JP2012143801A2012-08-02
JP2009095854A2009-05-07
Attorney, Agent or Firm:
AOKI, Noboru et al. (JP)
Aoki 昇 (JP)
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