Slow impact punching in brittle materials
Sakaguchi Ken-ichi; Nojima Taketoshi
Abstract:In order to develop an impact punching technique in brittle materials, slow impact punching tests were carried out in a soda lime glass and some engineering ceramics by using a specially designed clamping device made of a frame and a compact powerful jack. Punching works were performed by using 3 types of punches; the works by conical and spherical punches are successfully carried out without serious radial cracks around the punched hole, while by flat punch, not only the radial cracks are often produced in thick plates, but the load to form a hole is quite large. Therefore, the conical and spherical punches are adopted to investigate a possible range of punching. Although hole formation load depends upon the top radius R of the punch in thick plate, the effect of R is quite small in thin plate. This trend is explained very well by the formation of a Hertzian ring crack and its growth.