Abstract
This work is concerned with the algorithm of generating are splines for the purpose of machining cam profiles by CNC machine tools. This research presents a maximum error hypothesis that excludes error iteration between designed profile and generated arcs. A new circular interpolation method where a segment span is composed of three circular arcs, called a triarc, is suggested. Triarc curve fitting has the advantage of generating are splines easily. In the triarc method, the first are is generated from the start knot point to the position where the maximum error is equal to a given allowable tolerance, and the other arcs are generated from this position to the terminal knot point of each span. In generating the machining data in CNC machining with the biarc method and the triarc method for various cam curves, the latter accomplished fast NC-code generation and machined the same cam profile efficiently.