Time-optimal feedrate algorithm for non-uniform rational B-spline tool paths with process and machine tool constraints

Abstract

Feedrate planning is crucial for CNC machine tools to generate a smooth and efficient machining. In this paper, a feedrate optimization method is proposed for NURBS tool path with process constraints and machine tool constraints. The proposed feedrate profile is expressed in the cubic spline form which is a function of parameter u, and the optimal feedrate is achieved by iteratively modulating the feed control points of the cubic spline. Because the feedrate is designed in terms of u,there is no need to monitor the distance when the tool is accelerating and decelerating. In addition, the machining time can be calculated in advance, a proportional adjustment strategy can be used to improve the final interpolation accuracy. The performances of the proposed method are validated by performing simulations on a Star-shaped NURBS curve. The results show the effectiveness and reliability of the proposed feedrate optimization method.