Analysis of local loads on the draw die profile with regard to wear using the FEM and experimental investigations

The draw die radius of deep- and stretch-forming tools is exposed to strong tribological loads by high contact normal pressure and long sliding distances. Dies often show adhesive contamination of the tool surface or abrasive wear in this contact zone. For the development of effective wearing protection, knowledge about the local tribological loads is essential. The paper describes an approach to identify the characteristic distribution of local loads on the draw die surface. Therein the major influence parameters are analysed, such as sheet thickness, draw die radius, coefficient of friction, material parameters (aluminium vs. steel), the Young's modulus of the tools and the blank holder force. The contact pressure shows a very uneven distribution with characteristic local maxima. The load amount and position are analysed in dependency on the influencing parameters. Verification of the finite element simulation is done by strip drawing tests with bending. Starting from results of the finite element simulation and the experiments, first calculations for a new tool concept showing determinable local elasticity to reduce local tribological stress are presented. (C) 2001 Elsevier Science B.V. All rights reserved.