A unified geometric modeling method of process surface for precision machining of thin-walled parts

Thin-walled parts are widely used in aerospace, ships and automotive fields. However, due to the characteristics of multi-process and multi-procedure manufacturing technology, the production efficiency and machining precision of those parts are greatly limited. In this paper, a unified geometric modeling method for precision machining of thin-walled parts is presented. The unified model is established to represent the polymorphism of process surface for every stage in the whole machining process. Then with four variables, including design surface model, process surface model, offset transform and localization transform as well as the interactions among them, different application problems are described, which reveal the common mathematical essence. Firstly, for the process design of thin-walled parts, nonuniform allowance optimization design method is proposed based on the stable process stiffness. Secondly, for the rapid clamping and localization of thin-walled parts, a method of alignment localization with constraints and allowance optimization is presented for the near-shape blank. Thirdly, for the machining process controlling of thin-walled parts, a modeling and compensation method of elastic deformation error is developed in the multi-axis NC machining. Finally, several examples show that the geometric modeling method is feasible and the results can carry high precision and efficiency for thin-walled parts.