Tolerance optimization for sheet metal parts based on joining simulation

Abstract

In the industrial production process, the tolerance design of product is directly related to the product and production cost. This paper proposes an optimization method for the geometrical tolerance design of sheet metal parts based on joining simulation. Finite Element Method (FEM) is applied to simulate the influence of Body In White (BIW) joining process on the assembly deviation. Because the profile tolerance is widely used in the BIW sheet metal parts as the manufacturing requirements for the single parts as well as the assemblies to ensure the dimensional quality of the product, this type of tolerance on parts are mapped on the FE meshes in this work subjected to the Product Manufacturing Information (PMI). A sensitivity analysis is implemented to rank the tolerances by constructing meta-models. Without compromising the dimensional stability of the assembly, the geometrical tolerances of the single parts are optimized through a two-level optimization system. An automotive reinforcement assembly is studied to illustrate the proposed method. The maximum allowable tolerance ranges of the reinforcement part are adapted with respect to a pre-defined process capability index. The result provides a quantitative tolerance optimization strategy for BIW parts in an early development phase.