Study Of Tolerance Analysis Method Based On Newest GPS And Joint-datum Chain

The product with high quality and low cost is the goal of modern machinery industry. The geometrical and dimensional tolerances from the part design and manufacturing are delivered and accumulated by assembling the parts together. Then the tolerances affect the product function. Tolerance analysis is an important tool of reducing product research and development cycle, cost and improving product quality. And it’s the major section of dimensional engineering. The lag of computer aided tolerance analysis has restricted the manufacturing information integration. The existing tolerance models are based on certain assumptions, and they aren’t suit for3D dimension chain. Besides, the form tolerance, composite tolerance and the direction of the tolerance zone aren’t considered. And there is no unified and recognized model. With the release of the newest GPS, the major issues in the tolerance area are how to build3D tolerance model and analyze it under this standard.This paper focuses on the main issues of computer aided tolerance analysis technique at the present stage, puts forward the3D tolerance analysis method based on the newest GPS and joint-datum chain. The paper’s main works are as follows:1) Review the history and research Background of computer aided tolerance analysis and the newest GPS;2) Associate with ISO/TC213, expound the related concepts of the geometric product based on the newest GPS, analyze the relationship of the product, parts and features, connect the features and tolerances with variable geometric constraints;3) Build the hierarchy model of tolerance based on the product design information and design intend; analyze the types of the assembly joint, and build the assembly structure model, then obtain the stack-up path;4) Parametric modeling of the3D tolerance zone based on the spatial orientation theory and torsor theory, including the single tolerance, hole composite tolerances and combination tolerances;5) Describe the link in the parts with torsors, modify the torsor parameters along the direction of tolerance analysis, and verify the feasibility of this approach by a3D product.