An Approach of Assembly Deviation Analysis based on Jacobian Model and Skin Model Shapes

Form defects are an inevitable phenomenon in the process of part processing, which has great influence on the quality and performance of products. In initial design stage of products, generating tolerance representation model conforming to tolerance specification considering form defects is a key part to analyze and predict the assembly accuracy of product, and the skin model shapes (SMS) are proved to be valid in response to these needs. However, the spatial distribution characteristics of form defects (SDCFD) have not been concerned in existing research works when generating SMS, which may influence the assembly deviation analysis. In addition, the recent research on the calculation method of assembly deviation propagation and accumulation mainly focuses on the method of homogeneous transformation matrix, which has lower computational efficiency and complex operation. To solve the above problems, this paper presents an assembly deviation analysis method considering SDCFD based on Jacobian model and SMS, which contains two advantages of efficient deviation propagation and effective representation of tolerance. Firstly, the SMS is generated based on Non-Gaussian random field (NGRF) considering SDCFD; secondly, the positioning deviation between two mating surfaces (PDTMS) for serial connection and partial parallel connection are calculated with progressive contact method and constraint registration method, respectively; thirdly, the Jacobian model is applied to calculate the cumulative deviation of mechanical assembly according to function requirement. Finally, a case study is given to verify the proposed method.