Entwicklung prozessoptimierter Werkzeugtechnologien anhand eines seriennahen Zielbauteiles beim Thixoschmieden von Stahl
Beyer, Christophe Jean Daniel; Kopp, Reiner (Thesis advisor)
Aachen : Publikationsserver der RWTH Aachen University (2006)
Dissertation / PhD Thesis
In the process Thixoforging (forging in the semi-solid state) the advantages of the processes forging and casting can be combined. For example, complex geometries, which are normally produced in 4 or 5 steps, can be realised in one or two steps. In contrast to the forming of aluminium alloys in the semi-solid state, the forming of steel in the semi-solid state is much more difficult, because of the higher forming temperature. Common tools out of steel show a very important wear due to wetting, bonding and melting processes, which result in a very short tool life. The aim of this work was the development of appropriate tools for the thixoforming of steel. To develop appropriate tool technologies the entire process chain had to be analysed and optimised. Principle studies, forming tests and FEM-simulations show that the ceramic Si3N4 is very suitable as a material tool. The use of preheated tools of ceramic, the optimisation of the heating of billets with inert gas and particularly the development of the method of the aimed cooling before forming made possible the thixoforming of components with the same quality as forged ones. The process of thixoforming of steel offers very large potentials of cost savings, since the amount of machining work can be reduced and the process chain can be shortened for example by forming with an integrated joining process [KAL-02] or surface hardening.