A study on CAD/CAM interface for 3-D object based on rotational symmetry shapes - Derivation of removal primitives.

This paper describes the methodology of how to derive the removal shape element for NC machining from CSG model utilized commonly to various applications. An approach to establishing the CAD/CAM interface based on the geometry model must be effective to realize an integrated CAD/CAM system. From the point of realizing a CAD/CAM interface system mentioned above should be established the method for generating intermediate data which connects a machining data information to a geometry model. Here, CSG modeler TIPS-1 is adopted for this purpose and the NC machining oriented geometry data, which should be constructed by a set of the shape elements, is generated automatically from the 3-D geometry data of TIPS-1. The procedures are the following. (1) Translation of CSG model to B-Reps. (2) Extraction of characteristic shape unit on the machining by utilizing topological data of B-Reps. (3) Decision of intermediate shape in each step of machining. Thus, the removal primitive has the machining shape and the removal range can be obtained automatically from the geometry model.