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:
Feb. 22, 2000
Filed:
Mar. 12, 1998
Applicant:
Inventors:
Assignees:
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
C21D / ;
U.S. Cl.
CPC ...
148226 ; 148230 ; 298969 ; 72 53 ; 451 37 ;
Abstract
In a manufacturing method of a valve spring, a coiled valve spring made of an oil-tempered wire is applied with nitriding treatment and is supported to be rotated about its center axis. During a shot peening process of the coiled valve spring, cut wires of Hv 650 to 850 in hardness and 1.0 to 0.6 mm in diameter are shot to the coiled valve spring at a first step, in a roller-type shot machine and cut wires of Hv 650 to 850 in hardness and 0.4 to 0.2 mm in diameter are shot to the coiled valve spring at a second step in a tumbling shot machine, the time for the second step being longer than the time for the first step.