Generation of swept volumes of toroidal endmills in five-axis motion using space curves

Abstract

Accurate prediction of the swept volume of a cutting tool is essential in NC verification algorithms for detecting deficiencies in a proposed tool path, such as gouging, undercutting and interference. This paper explores a new technique for generating the swept volume of a toroidal endmill, and analyzes the results obtained for two test cases. For a given tool location along a path, a curve on the cutting surface of the tool is identified that rs:presents the imprint of the tool on the machined surface. This curve will be designated a space curve as it is defined in 3D spa.ce. The method relies on forward difference information obtained from a G-code or cutter location data file in order to compute the space curves. Once several su.ccessive space curves have been identified, a facetted surface model of the footprint of the tool along a pass may be readily calculated and compared with the design surface. The method has b,een verified for two test cases: a) 5-axis tool path on a hemispherical cavity and b) a 5-axis tool path on the complex surface of a turbine blade. Results from the new method are compared with the slow, but dependable mycasting technique. It is concluded that the new technique offers al fast and accurate method of verifying multi-axis tool paths. In the future, it is hoped that the simulation can be extended to all cutter shapes, and not be limited to toroidal cutters. CR Categories and Sub.ject Descriptors: 1.6.4 [Simulation and Modeling]: Model Validation and Analysis Additional