| 摘要 |
PROBLEM TO BE SOLVED: To provide a punching method of a high-strength steel sheet by which the residual stress in the punched hole of the steel sheet is reduced and the deterioration of delayed fracture withstanding property of the high-strength steel sheet is prevented. SOLUTION: In this punching method of the high-strength steel sheet, by using a tool which has a bending edge having a projecting shape in the top end part of a cutting edge of a punch and/or a die, is≥0.2 mm in the radius of curvature of the shoulder part of the bending edge and/or 100-170°in the angle of the shoulder part of the bending edge, the clearance is taken as≤25%. COPYRIGHT: (C)2006,JPO&NCIPI
|
