A CAD/CAM Representation Model Applied to Tolerance Transfer Methods

Abstract

This paper presents the adaptation of tolerance transfer techniques to a model called TTRS for Technologically and Topologically Related Surfaces. According to this model, any three-dimensional part can be represented as a succession of surface associations forming a tree. Additional tolerancing information can be associated to each surface association represented as a node on the tree. This information includes dimensional tolerances as well as tolerance chart values. Rules are then established to infer tolerance chains or stack up along with tolerance charts directly from the graph. This way it becomes possible to combine traditional one dimensional tolerance transfer techniques with a powerful three-dimensional representation model providing high technological contents.