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:
Jan. 10, 2012

Filed:

Mar. 11, 2009
Applicants:

Takuo Kobayashi, Tochigi, JP;

Izuru Hori, Tochigi, JP;

Inventors:

Takuo Kobayashi, Tochigi, JP;

Izuru Hori, Tochigi, JP;

Assignee:
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
B23P 17/00 (2006.01); B21D 15/03 (2006.01); B21D 26/02 (2011.01); B21J 5/04 (2006.01);
U.S. Cl.
CPC ...
Abstract

A bulge forming method includes arranging a raw material tube inside a die having an inner surface shape, in which plural crest portions and root portions are alternately formed, and providing a rod inside the raw material tube in the axial direction of the raw material tube, and the rod has a pressurized liquid supply opening. The bulge forming method further includes providing a pair of sealing portion having the pressurized liquid supply opening therebetween, and the sealing portions seal a space between the raw material tube and the rod. The bulge forming method further includes moving the rod in the axial direction while applying compressive stress to the raw material tube in the axial direction and supplying a pressurized liquid from the pressurized liquid supply opening into the raw material tube, whereby the raw material tube is formed into the shape of the inner surface of the die.


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