Title:
HOLE EXPANSION TEST METHOD
Document Type and Number:
Japanese Patent JP2020001068
Kind Code:
A
Abstract:
To provide a new hole expansion test method which can exactly evaluate press formability and so on even for a test piece having a strain history (plane strain).SOLUTION: A hole expansion method by which a punch (P) is pushed into a hole (123) of a test piece (12) of which an end is gripped, and evaluation for conditions that cause cracks at a hole edge and so on. Plane strain has been previously imparted to the test piece before testing. The hole of the test piece is an elliptical hole with a long axis in a maximum main strain direction of plane strain. The punch is an elliptic conical punch having a side face of which a cross section orthogonal to a central axis is elliptical. A hole expansion test is performed in such a manner that a short axis of an ellipse of the elliptic conical punch is located in the maximum strain direction of plane strain. It is preferable that for example, an ellipticity, which is a ratio of a short diameter to a long diameter, of the elliptical hole and the elliptic conical punch has an ellipticity, is 0.75 to 0.95. According to this hole expansion test method, cracks may occur in a plane strain area of the test piece.SELECTED DRAWING: Figure 7
Inventors:
IWATA NORITOSHI
ICHIJO NAOKI
ICHIJO NAOKI
Application Number:
JP2018123478A
Publication Date:
January 09, 2020
Filing Date:
June 28, 2018
Export Citation:
Assignee:
TOYOTA CENTRAL RES & DEV
TOYOTA MOTOR CORP
TOYOTA MOTOR CORP
International Classes:
B21D22/00; B21D19/08; G01N3/30
Attorney, Agent or Firm:
Morioka Masayuki
Sansui International Patent Office
Sansui International Patent Office