Mechanically Joined Extrusion Profiles for Battery Trays

Abstract

In the context of electromobility, ensuring the leak tightness of assemblies is of paramount importance, particularly in battery housings. Current battery housings, often featuring base assemblies crafted from extruded aluminum profiles, address the challenge of leak tightness at joints through methods like friction stir welding, a process known for its time and cost intensiveness. The aim of this study is to develop and implement a new type of extruded profile concept to produce tight base assemblies for battery housings by a longitudinal mechanical single stroke joining process. The geometry, the process and the properties of the aluminum profiles are investigated to get a joint that meets the tightness requirements and achieve high load-bearing capacities in agreement with the high homologation requirements set to vehicles with high-voltage systems. The joint is formed by means of a single stage press stroke, which eliminates the need for complex tool designs that are necessary for continuous joining (roll joining). Flat steel contact surfaces are used as joining tools. To evaluate the joint quality, force curves from the joining process are analyzed and the resulting joint geometries are assessed using micrographs. The resulting leak tightness of the linear joints is measured by a helium sniffer leak detector and the load-bearing capacities are investigated by shear lap and bending tests and fatigue strength test. The study also explores whether a difference in strength between the two joining partners has a positive effect on the joint properties.