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:
Apr. 20, 2004
Filed:
Feb. 07, 2002
Chugai Ro Co., Ltd, Osaka, JP;
Abstract
A steel workpiece maintained at a specified quenching temperature is rapidly cooled to a temperature just above the martensite transformation start point (Ms point) by being immersed in a high-temperature quenching oil. Thereafter, the steel workpiece is taken out of the high-temperature quenching oil so as to be soaked by the heat possessed by the steel workpiece and subsequently cooled by being immersed in the high-temperature quenching oil. Through these processes, a temperature difference between steel workpieces or the portions of a steel workpiece in the martensite transformation stage is reduced, and a cooling speed in a high-temperature region (not lower than about 550° C.) is made to be a slow speed sufficient for restraining a thermal distortion, by which the quenching distortion and quenching variation can be reduced.