Development of a modified tool system for lateral angular co-extrusion to improve the quality of hybrid profiles

Abstract

The application of monomaterials is limited in lightweight construction concepts, because in addition to the weight requirements, the thermal and mechanical demands are constantly increasing. In order to ensure that the right material is used in the right place, the Collaborative Research Centre (CRC) 1153 is concerned with research into innovative process chains that lead to components with locally adapted properties. The lateral angular co-extrusion approach (LACE) allows the manufacturing of hybrid semi-finished products from aluminium alloy EN AW-6082 and steel AISI 5120. Throughout the LACE process, the steel tube is inserted into the extrusion die at an angle of 90° to the pressing direction, where it is covered in aluminium. The coaxial semi-finished products are subsequently formed into a hybrid bearing bushing by die forging. In this study, the LACE process is investigated on an industrial scale using a 10 MN extrusion press. The investigations are carried out by means of finite element (FE) simulation and are validated by a comparison with experimental results. The focus of this study is on the design and improvement of the aluminium material flow. The two major challenges of hybrid profile extrusion are the straightness of the extruded profile and, particularly in this study, the coaxial position of the support element. Within the numerical design process, different mandrel positions and chamber geometries are considered in terms of their influence on the profile quality. The numerically determined tool geometries are subsequently used for experimental investigations using the 10 MN extrusion press. The extruded hybrid profiles are compared with results of the numerical simulations. For the validation of the numerical model, metallographic analyses of the hybrid profiles as well as experimental extrusion force-time curves are used. Based on these results, the final mandrel position and chamber geometries are chosen and serve as a basis for further co-extrusion experiments.