Recent developments in flat-clinching

Due to the rise in intelligent light weight construction and the resulting change in joining technologies, flat-clinch-technology was developed at the Chair of Virtual Production Engineering at Chemnitz University of Technology. Using this technology, it is possible to join materials of the same kind (metal and metal, e.g., steel and aluminum), as well as materials of different kinds (e.g., aluminum and plastics). The process is a single step mechanical joining method that combines materials without any preparatory work (e.g., pre-punching, chamfering) or additional complementary joining elements (e.g., screws, rivets). The material flow during the deformation is decisively influenced so that the join materials cramp; a characteristic feature of clinch connections, which results in a force- and form-closed interlocking within the total material thickness. Thus, a one-sided planar material compound is created, which in contrast to connections produced in conventional clinching processes, does not show the die-sided protrusion extending out of the material plane. Therefore, flat-clinch-technology can be successfully applied even in visible areas and functional surfaces. rmation of the mechanical interlocking within the total material thickness is a process influenced by numerous factors with multi-factorial relationships. In order to quantify these factors and to display the material flow during the formation of the connection, the joining process was modeled by means of the Finite-Element-Method (FEM). By performing a systematic numerical analysis it was possible to optimize the parameters that influence the forming of the interlocking and consequently the shear strength and tensile strength of the compound. The numerical simulation models were validated by experimental investigations.