CAD approach for simulation of generation machining and identification of contact lines

A surface in generation machining is obtained as an envelope of a series of cutter surfaces formed during kinematic motion between workblank and cutter. Extensive work has been carried out to obtain the generated surface using coordinate transformation and differential geometry approach. In this paper, CAD approach is used to simulate generation machining process. For this purpose, the cutter and workblank are taken as solid models and simulation is performed using Boolean operation to remove unwanted material in an incremental manner, maintaining the kinematic relationship. A computer program in C is developed to generate relevant script file, which is then executed in a solid modeling package to simulate generation machining. This approach is demonstrated by taking simple cases of helical groove machining with disc-type and pencil-type cutters and a complex case of worm gear machining. Solution to reverse problem of arriving at cutter geometry from given work surface is also obtained by this approach. Use of the CAD approach in identifying the contact lines has also been reported, taking helical gear pair as an example.