Papers by Author: Jan Philipp Schmidt-Ewig

Abstract: Within traffic engineering, the importance of lightweight space frame structures continuously grows. The space frame design offers many advantages for light weight construction but also brings challenges for the production technology. For example, the important requests concerning product flexibility and reconfiguration can only be achieved with a high technical effort, if current machine technology is used. For this reason, the collaborative research center SFB/TR10 investigates the scientific fundamentals of a process chain for the product flexible and automated production of space frame structures. An important component in space frame structures are curved extrusion profiles. Within the investigated process chain, the extrusions must be machined mechanically in order to apply holes and to prepare the extrusion ends for the following welding operation.The machining is currently done by clamping the profile into a fixture and processing it within a machining center. This procedure has two disadvantages due to the complex geometry and the partially high length of the extrusion profiles: On the one hand, a complex fixture is needed for clamping the work piece [1]. On the other hand, a machining center with a large workspace and five machine axes is required [2]. Due to this, the product flexible machining with current technology is only possible with high technical and economical effort. For this reason, a new machine concept for the product flexible machining of three dimensionally curved extrusion profiles was developed at the University of Karlsruhe. In this paper, the function of the machine is explained and a prototype is presented. In addition, investigation results of the machining accuracy are shown and possibilities for improving the precision are discussed.

Abstract: The importance of rigid and self supporting space frame structures for the automotive and aerospace industry continually increases. To meet the market requirements for a flexible and competitive small batch production, innovative machine concepts must be investigated. By integrating handling and machining capabilities into one machine structure, redundant degrees of freedom can be reduced and a former idle economic potential can be made use of. This paper introduces a systematic approach to reveal synergetic potentials that emerge by integrating two different fields of function, the handling and the machining. Therewith a matrix with technical solutions for a combination of handling and machining is generated. These solutions are the base for new machine concepts that fulfill both tasks with a minimal number of machine axes. The authors present a machine concept which is combined out of a four-axes parallel kinematics and a conventional serial kinematics. The two kinematic structures collaborate and allow the product flexible handling and machining of three dimensional rounded extrusions with a minimal technical effort. The machine concept is dimensioned and optimized for a maximal stiffness by the coupling of a multi body simulation to an external parameter optimization software. The optimization results show that the stiffness of the machine concept could be explicitly improved. This paper is based on investigations of the collaborative research centre SFB/TR10 which is kindly supported by the German Research Foundation (DFG).