Developed in this research is an overall procedure of machining sculptured surfaces, starting from a set of measured point data. The research identifies possible difficulties in implementing such a procedure, and then proposes methods of overcoming them. The procedure consists of three parts: Input data transformation, surface interpolation, and cutter paths generation.
The input data transformation step consists of modifying irregular data points and providing additional gradient information. To achieve required smoothness of the surface, the measured raw data have to be modified to correct possible measurement errors and to supplement missing information. An interactive smoothing method is employed. To provide end conditions (gradient information), an automatic algorithm is introduced. The modified point data are still inadequate to produce a smooth interpolant (bicubic parametric surface). Thus, a remeshing step is necessary to obtain a set of evenly spaced data points. A new remeshing procedure is developed based on the flow rate of parametric curves.
The generated cutter paths should meet tolerance requirements while avoiding any interference between the cutter and workpiece. An efficient non-iterative algorithm is developed to determine required step lengths and path intervals. Also introduced are a procedure for checking cutter-workpiece interference and a method of determining reasonable cut distribution during rough cuts. The entire procedure has been implemented in BASIC on an IBM PC.
