Forming Limits for Quasistatic and Dynamic Working-media-based Forming Processes

Abstract

The production of complex, multi-functional, high-strength components is becoming increasingly important in the sheet metal industry. Especially with small batch sizes, quasi-static working-media-based forming processes (WMF), such as hydromechanical deep drawing (HMD) or high-pressure sheet metal forming (HPF), can be advantageous. If shorter process times or higher forming speeds are necessary, working-media-based high-speed forming processes (WMHSF) are best used. These permit the production of sharp edged parts with less tooling than for quasi-static WMF. The successful use of WMB processes requires knowledge of the significant process parameters and the material characteristics under process-specific conditions. This paper describes the new approach of a modified hydraulic bulge test, which permits the flexible determination of forming limit curves (FLC) under true quasi-static and dynamic WMF process conditions. Results for the formability of steel DC04 and aluminium (A5754, A1050) alloys in the WMF process are shown. Here, the dynamic conditions are analysed through the use of pneumo-mechanical (PMF) testing equipment. The application of quasi-static forming conditions is analysed in high-pressure sheet metal forming (HPF) processes. A comparison of the maximum strains of parts formed by HPF and PMF shows that quasi-static and dynamic working-media-based forming processes lead to different forming limits.