Development of a segment-hydro-elastic blank holder for the deep drawing process
During the deep drawing process of non-rotationally symmetric parts non-uniform deformation conditions appear in the flange area. Due to the high tangential compression in critical areas, a sheet thickness increase appears. These cause an increased surface pressure in the blank holder. In consequence, an increased drawing force is required which will restrain the material flow and will cause failures in the workpiece.
The objective of this project is to reduce the drawing force with the help of segment-hydro-elastic blank holders. These will compensate sheet thickness increase and will reduce the blank holder force as well as the deep drawing force. The areas with low thickness increase will be modeled rigid and areas with a high thickness increase will be designed as elastic.
A methodical approach which was developed for the design of active-elastic tool systems (ACTEC) and the use of the finite-element-method (FEM) enables stepwise dimensioning of the flexible areas of a segment-hydro-elastic blank holder. The dimensioning will be done accordingly to the sheet thickness distribution obtained from the finite element analysis with rigid tools. Hence, the tool system will be designed to compensate the inhomogeneous thickness distribution in the flange area. A sensitivity analysis of the part and the process parameters reveals the time-dependent on-site distribution of the loading. Experimental investigations will show the effectiveness of the tool system in comparison with the rigid tools as well as in comparison with the FE results.