Influence of tribological conditions and continuously variable contact pressure on the process of the thin sheet sliding during the flat-die test

Abstract

Influence of the contact pressure in the deep drawing processes is a very actual research topic in the thin sheets forming technology. In this research a tribological model was developed, based on the process of a strip sliding between the flat contact surfaces during the continuous setting of the variable contact pressure and an original experimental computerized device was created. During the process, a complex multifactor experiment was conducted, by application of single-sided zinc coated low carbon steel sheet and the variable contact pressure. The oil for deep drawing was applied as a lubricant. Experimentally obtained variations of the drawing force and the friction coefficient along the sliding path are presented in this paper, as well as the description of the experimental device. Dependencies of the drawing force were obtained for each of the experimental conditions, based on the predefined functional variations of the contact pressure. By calculating the friction coefficient, based on the obtained drawing forces, it is possible to monitor the influence of tribological factors on the process of the strip drawing in the variable pressure conditions. In this way, it is possible to perform the analysis of comparative influence of the contact elements' surfaces conditions and the pressure functions.