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:
Sep. 18, 1990
Filed:
Mar. 30, 1989
Kazuto Nakajima, Yamatokouriyama, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
A method of forming a collar-shaped protrusion on thin plate material by relatively bringing a forming punch having the outer diameter varying stepwise into the forming hole of a forming die and during forming, punching a small diameter hole by means of a punch-through punch incorporated in said forming die. During the remainder of forming, ironing and burring are performed on the protrusion to form a collar for heat exchanger fins. The die set shaped for carrying out the steps is also included. Since these steps can be performed as a single continuous series of steps, heat exchanger fins of high accuracy can be manufactured with fewer tools, and at less cost and in less time than heretofore.