Abstract: In precision machine assembly process, the product quality is not only depended on the tolerance design, but also on the assurance of the assembly process planning. Therefore, there is a strong need to develop a mathematical analysis method to predict and control the variation in assembly process, and to find out the assembly process effect to final accuracy. By the expression of the variation state in different assembly process in form of differential motion vector(DMV) method, a generic mathematical model that directly links variation of key characteristics(KCs) and the assembly process variation sources is built. The state space model describing variation propagation of KCs in machine tool assembly, measurement and adjustment is proposed. Based on this model, the effect of current assembly and adjustment process to final accuracy can be predicted to decide the current adjustment method to the final assembly accuracy assurance. The method’s validity is verified by a simulation of the assembly of a precision horizontal machining center.

Key words: Assembly process, Machine tool assembly, State space model, Variation propagation