| 摘要 |
PROBLEM TO BE SOLVED: To provide a galvanized steel sheet which is excellent in rust resistance of the cut end face, a die suitably used for obtaining the same, and a cutting processing method. SOLUTION: When a galvanized steel sheet, in which the coating weight of Zn per one surface is ≥10 g/m<SP>2</SP>and the sheet thickness is ≤2.0 mm, is cut by using a die constituted of a die, a punch and a die press, the shoulder part of one of the die and the punch on the product steel sheet side is rounded in such a manner that the radius curvature is 0.1-0.50 times of the steel sheet thickness, and the shoulder parts of the other and the die press are right-angled, and further the side faces of the die and the die press are made even, and the clearance between the die and the punch is set to be ≤1.0% of the steel sheet thickness. Thereafter, cutting processing is carried out so as to form an end face having a shear section ratio of ≥90% and a covering ratio of zinc of ≥50%. COPYRIGHT: (C)2010,JPO&INPIT |
