USING VIRTUAL BOUNDARIES FOR THE PLANNING AND MACHINING OF PROTRUSION FREE-FORM FEATURES

Sculptured surfaces are frequently encountered in modern engineering designs. Sculptured surface machining is a time-consuming and error-prone process. It is critical that proper tools are selected and cutter paths generated. In this paper, a method called the virtual boundary approach is proposed to integrate a protrusion free-form surface feature with conventional polyhedron features in a feature-based design and manufacturing system. Using the proposed virtual boundary approach, a protrusion free-form feature can be converted into a virtual pocket with islands. The machining of a protrusion sculptured surface feature is transformed into a series of virtual pocketing processes. The proposed methodology transforms the union operation of a protrusion free-form feature into a difference operation of removal volumes. Techniques of automatic cutter selection and cutter path generation are presented. A complete operation plan and cutter path can be generated for machining using the proposed virtual boundary method. Practical examples and automatic cutter path generation for machining are also presented.