A double circular arc fitting algorithm for CNC machining of non-uniform scroll components

Abstract

Scroll compressors have been widely used in refrigeration and air conditioners. The manufacturing of scroll components with complex shape and of high precision constitutes a very important task in guaranteeing the performance of a scroll compressor. Uniform scrolls with constant wrap thickness may be availably machined by generating method. However, for the machining of non-uniform scrolls with variable wrap thickness, the generating method is no longer applicable. The current practice in the machining of non-uniform scrolls is to apply a numerical method using CAD/CAM software in a CNC milling machine. This process is data-intensive and the machining quality is not reliable as the tool path generated does not have G1 continuity. In this paper, the authors present a double circular arc (DCA) fitting algorithm for high-precision manufacturing of non-uniform scroll components. The proposed algorithm is validated by cutting experiments on a CNC milling machine, which incorporates the DCA fitting algorithm–based finishing machining and NC tool path code generation. Test results have shown that the application of DCA fitting algorithm to non-uniform scroll machining is effective, not only in decreasing the number of generated tool path points, but also with satisfied machining precision.