Paths Generated Research Articles

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.

Real-time CNC Tool Path Generation for Machining IGES Surfaces

A real-time CNC tool path generation algorithm has been developed for machining IGES surfaces. IGES-based CAD data files can be directly inputted to the CNC system and the tool paths generated in real time can be passed to a motion controller during cutting via a Multibuss II backplane structure. The development of such a real-time tool path generation method has eliminated the need for a tradeoff between the desired surface accuracy and the required memory size for storing off-line generated NC codes. The real-time NC path generation algorithm can properly deal with issues such as trimming lines, gouging detection, and adaptive tool step adjustment. The developed algorithm has been implemented on a multi-processor CNC system and verified through actual cutting tests. The test results show that no violating conditions occurred on machined part surfaces, and the surface contour error of the cut part is less than the given tolerance, which was 0.02 mm in this particular test.