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. 15, 2000
Filed:
Feb. 02, 1998
Applicant:
Inventors:
Takeshi Yabushita, Yokohama, JP;
Noritoshi Takamura, Yokohama, JP;
Mitsutoshi Kaneyasu, Yokohama, JP;
Michihiko Ayada, Yokohama, JP;
Assignee:
NHK Spring Co., Ltd., , JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
F16F / ; C23C / ;
U.S. Cl.
CPC ...
267166 ; 267180 ; 148226 ;
Abstract
By controlling the thickness of the nitrization layer formed on the surface, the coil spring made of spring steel may be made highly resistant to permanent set and fatigue. By carbonitriding the material of the coil spring to a depth of 20 to 50 .mu.m from the surface thereof so as to have an internal hardness of Hv 540 or higher, the coil spring can be made to endure 10.sup.7 cycles of repeated high stress without suffering any significant permanent set.