Identification of process limits for punching with a slant angle

Abstract

In order to experimentally identify process limits during punching with slant angle, a test tool was manufactured at the Institute for Metal Forming Technology (IFU) for in-situ measuring the horizontal punch deflection. The modular design of a test tool enabled the variation of numerous cutting parameters such as the "cutting clearance", the "punch length" or the "slant angle". Considering current lightweight construction trends in automotive industry, sheet metal materials HC340LA, DP600 and DP1000 were investigated, since these high-strength steel materials allow the use of relatively thin sheets in modern car body designs. As a result of investigations carried out in single stroke testings, a cutting parameter-dependent overview of maximum possible slant angles could be obtained, which was not yet available according to the current state of the art. Based on gained results, design guidelines for tools for punching with slant angles were derived, which were subsequently validated by endurance tests performed under lab conditions. In summary, the research work carried out does not only show a list of the maximum possible slant angles. Rather, it was possible to work out the insight that the process limits for punching with slant angle are assumed to be too conservative in industrial practice. For example even the high-strength sheet material DP1000 was punched reliably with a punch diameter of d=5mm up to a slant angle of 17.5°. In industrial practice, a cost-intensive cam solution would have been used from a slant angle of approx. 5°.