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:
Nov. 02, 2010
Filed:
May. 13, 2009
Masakazu Ooka, Naka, JP;
Yoshiki Hiyama, Naka, JP;
Kentaro Tanabe, Naka, JP;
Yoshiyuki Kanzaki, Fukushima, JP;
Satoshi Sato, Fukushima, JP;
Yoshihisa Yamazaki, Fukushima, JP;
Kiichiro Goto, Fukushima, JP;
Masakazu Ooka, Naka, JP;
Yoshiki Hiyama, Naka, JP;
Kentaro Tanabe, Naka, JP;
Yoshiyuki Kanzaki, Fukushima, JP;
Satoshi Sato, Fukushima, JP;
Yoshihisa Yamazaki, Fukushima, JP;
Kiichiro Goto, Fukushima, JP;
Ibaraki Steel Center Co., Ltd., Ibaraki, JP;
NOK Corporation, Tokyo, JP;
Abstract
The problem to be solved by the present invention is to clear up an eccentric load onto a pin and a problem of deformation and cavity due to flowing material during extrusion when spring washer blind-holes in a piston for an automobile transmission are formed by extrusion with a pin. After an annular region along the peripheral edge portion on the back of an end plate of a secondary workpiece is flattened, the secondary workpiece is set on a lower die. Further, while the lower die is pressed with upper dies and cushion pressure is applied on the lower die, pins, for piercing the spring washer blind-holes are made to perform an extrusion operation onto the end plate of the secondary workpiece from the backside of the end plate. The extruded material is made to flow into recess holes of the upper die, and thus spring washer blind-holes are formed. Then, projections which have flowed and protrude on the front side are removed by turning with a lathe.