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. 18, 2017
Filed:
Jul. 12, 2011
Yuichi Hirata, Nagoya, JP;
Hidekazu Suzuki, Nagoya, JP;
Hiroyuki Ogiso, Nagoya, JP;
CHUO HATSUJO KABUSHIKI KAISHA, Nagoya, JP;
Abstract
A method of producing a spring which reduces time required for a heat treatment step of eliminating a machining strain generated by a forming step is provided. This production method is provided with a forming step (S) of forming a spring steel material into a spring shape and a heat treatment step (S) of eliminating a machining strain generated in the spring steel material by the forming step. The heat treatment step is executed by electrically heating the spring steel material by applying a current thereto. The heat treatment step has a first step of heating the spring steel material to a predetermined set temperature and a second step of keeping the spring steel material at the set temperature for a predetermined set time period subsequent to the first step. The set temperature is set to be higher than 430° C. but not higher than 500° C.