Batch Fluctuations in Short Cycle Stretch Forming of Tinplate can Bodies

Abstract

Short cycle stretch forming (SCS) is an innovative stretch forming technology, developed by the Institute for Metal Forming Technology (IFU) at the University of Stuttgart. The SCS technology combines plane pre-stretching and deep drawing operations within the same stroke of the press ram. The sheet metal thickness is reduced, and the denting resistance as well as the yield stress are increased due to hardening effects.In this study, the SCS technology is applied to rotational-symmetric bodies. A process simulation of an SCS cupping process was carried out for producing tinplate cans. Based on these results, a tool was produced. First results showed that the metal thickness of cups for two-piece drawn and ironed (D&I) steel can bottoms can be reduced. With this technological goal, it is possible to save the material cost in series production.This paper analyses how batch fluctuations affect the thinning of cup bottoms in SCS cupping. Therefore, preliminary experiments have been conducted, using their results to improve the previously used FE process model. With the aid of this model, an FEA-based parametric study on the variation of material properties is conducted. To examine batch fluctuations, tensile tests have been taken into account, and initial material parameters for simulation, such as friction coefficient, initial blank thickness, Lankford parameter and hardening behaviour, have been varied.The results of this paper show that SCS cupping offers a promising potential for material savings and demonstrate the main effects of batch fluctuations.