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.

Date of Patent:
May. 21, 2002

Filed:

Feb. 09, 2001
Applicant:
Inventors:

Yuichi Nagao, Omiya, JP;

Takeshi Tatsumi, Tochigi-ken, JP;

Yoshihisa Doi, Utsunomiya, JP;

Attorney:
Primary Examiner:
Int. Cl.
CPC ...
B21J 1/302 ;
U.S. Cl.
CPC ...
B21J 1/302 ;
Abstract

A hydraulic pressure control apparatus comprises a high pressure accumulator for sucking pressure oil supplied to a relief chamber of a relief valve to make changeover for the relief valve from a valve-closed state to a valve-open state when a forming load is applied to the pressure oil charged in a pressure chamber and the hydraulic pressure of the pressure oil arrives at a relief preset pressure, and a low pressure accumulator for sucking the pressure oil charged in the pressure chamber via the relief valve which is in the valve-open state.


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