Versatile self-piercing riveting with a tumbling superimposed punch

Abstract

Abstract. Increasing resource efficiency is a major challenge and affects almost every aspect of social and economic life. The mobility sector in particular is responsible for a large share of primary energy consumption and is increasingly in the focus of public interest. One possibility to adress these challenges is to reduce the vehicle weight by means of lightweight construction technologies such as multi-material systems. These assemblies consist of workpieces with different mechanical and geometrical properties, which poses a major challenge for joining technology. Mechanical joining processes such as semi-tubular self-piercing riveting are often used in the production of these assemblies, but due to their process characteristics, they are rigid and can only react to changing process variables to a limited extent. One way to increase the versatility of self-piercing riveting is to superimpose a tumbling kinematics on the punch. During tumbling, an angular offset of the punch axis to the tool axis is set and the contact area between punch and workpiece is reduced. In this work, investigations were carried out to determine how the tumbling strategy, consisting of the parameters tumbling angle, tumbling onset and tumbling kinematics, affects the material flow of the rivet element. For this purpose, experimental tests are conducted with the typical materials of conventional multi-material systems and the geometric joint formations are determined by means of macrographs.