Method to compensate production related deviations for the assembly of space-frame-structures

The use of light space-frame-structures made of extruded aluminum profiles is a considerable contribution to weight reduction in cars. Individual customer demands as well as new concepts for drives result in splitting the number of pieces into several variants and therefore are increasingly leading to a small batch production of this kind of space-frame-structures. Due to the use of innovative processes and the small batch character of the production, bigger deviations usually occur during the manufacturing of individual profiles. These deviations represent a serious challenge for the precise and automated assembly. In this paper, a method to compensate production related deviations for the assembly of space-frame-structures will be presented. The general approach is the machining of the end segments. During the first step a target structure will be analyzed. Based on this analysis, all profiles are classified according to their degrees of freedom and the associated suitability for compensation. Deviations that occur become visible at an early stage by comparing them with actual measured profile data. Based on this, a strategy for compensating existing deviations can be defined. By implementing the correlations in a flexible environment, an optimization of individual profiles under different basic conditions is therefore possible, and leads to an improved accuracy of the space-frame-structure that needs to be assembled. © 2013 German Academic Society for Production Engineering (WGP).