Method of shearing thin metal sheet

Abstract

A method of shearing a thin metal sheet having a thickness of approximately 0.1 mm or less so as to be separated into a product and scrap by a pair of dies. A chamfer or a round having a size of approximately from 5 to 10 times greater than the thickness of the thin metal sheet is arranged at the lip of a first die which presses one portion of the thin metal sheet which is to be scrap. A chamfer or a round is not substantially arranged at the lip of a second die which presses the other portion of the thin metal sheet which is to be a product. A backing material and the thin metal sheet are overlapped so as to be a laminate. The backing material has a thickness of approximately 2 times or more greater than that of the thin metal sheet and is formed of a flexible material having a very small elongation and is soft enough not to substantially prevent the thin metal sheet from being sheared, such as, for example, paper. The laminate is arranged such that the backing material faces the pressing surface of the first die and that the thin metal sheet faces the pressing surface of the second die. Then, the thin metal sheet and the backing material are sheared concurrently. Thus, the thin metal sheet can be sheared, by methods such as blanking and piercing, while inhibiting burring, without requiring any special type of device or blanking die.

Dependencies are inferred from the claim text.