Project Details
Projekt
Dry Deep Drawing of Aluminium for Automotive Production
Applicants
Dr.-Ing. Roland Müller; Professor Dr.-Ing. Andreas Schubert; Professor Dr.-Ing. Frank Vollertsen
Subject Area
Primary Shaping and Reshaping Technology, Additive Manufacturing
Term
from 2013 to 2018
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 244972655
In the automotive industry, lubricants are applied in forming processes to expand the technological boundaries by reducing friction and wear. The desire for ecological production by forgoing lubricants must not lead to a reduced competitiveness of European manufacturers.The aim of the project is to enable dry deep drawing of aluminum sheets to the extent that process limits are at the same level as in lubricant based forming. This is intended to be accomplished by locally applied and textured wear resistant carbon based coatings onto steel tools to archive a higher tool capacity locally.In the first funding period a stress analysis was executed to determine the strongly stressed areas of a tool surface in a deep drawing process. Strip drawing tests with structured and a-C:H:Si coated drawing tools showed, that the friction coefficient in dry forming can be decreased by a reduction of the percentage of the contact area through micro structuring. However the level of the determined friction coefficient is too high because of huge adhesion, compared to lubricant based forming.Furthermore it was proved that the incorporation of silicon atoms into a CVD- diamond layer influences the electric conductivity to such a degree, that electrical discharge machining (EDM) gets feasible.In the applied funding period the residual tensile stress within the CVD- diamond coating with a PVD diffusion barrier on steel will be further investigated, as this can lead to a spalling of the coating under additional load in the forming process. To archive a favorable inherent stress condition and a good adhesion strength, the temperature profile of the CVD-coating process will be adjusted, the transition from the diffusion barrier to the diamond coating will be graded and the steel substrate surface will be micro structured by machining. In addition to that the flow of material of the work piece will be influenced by micro structuring the active areas of the forming tool as well as by smoothing and setting of a defined roughness by EDM-machining of the CVD-diamond surface.Subsequently, the new developed tool coatings and structures are exposed to different load cases. To represent a deep drawing process a square cup test is chosen. After the experimental baseline investigations, the knowledge should be transferred to an application oriented 3D-tool surface of a foot of the B-pillar of an autobody.
DFG Programme
Priority Programmes
