The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 19, 2002
Filed:
Oct. 20, 2000
Kazuhiko Tanaka, Kuwana, JP;
Hirofumi Nishiwaki, Suzuka, JP;
Denso Corporation, Kariya, JP;
Abstract
A manufacturing method is provided that produces a tubular metallic shell for spark plugs. The metallic shell has a tapered part in the outer periphery to provide a seal. The tapered part can be formed into a desired shape by cold forging operation. A first processed part has a first tapered part with a tapering angle A formed in the first processing step. In the second processing step, the first tapered part is transformed into a second tapered part having a tapering angle B. This is accomplished by utilizing a stepped inner cavity with a second molding die with a tapered bearing surface having a tapering angle B which is greater than the tapering angle A. In the third processing step, the second tapered part is transformed into a third tapered part with a tapering angle C. This is accomplished by utilizing a stepped inner cavity with a third molding die with a tapered bearing surface having a tapering angle C which is smaller than the tapering angle B. It also utilizes a third punch having a tip part whose outer diameter is smaller than the outer diameter of the small diameter foot part of the second processed part.