Smoothing for optimal feed rate of CNC machining time

WANG Qi, WANG Gui-rong
(College of Mechanical and Electrical Engineering, China Jiliang University, Hangzhou 310018, China)

Abstract: Aiming at the problem of insufficient smoothness in the time optimal feed rate planning of CNC machining, feed rate planning, highorder constraints and curve smoothing were researched, and a method for smoothing the time optimal feed rate curve with fixed areas was proposed. The Bspline curve was used to express the feed rate curve, and the time optimal model was established with constraints such as machine tool driving constraints, and the heuristic algorithm of binary search was used to obtain the optimal feed rate curve of processing time. Considering the situation of violation of feed rate planning constraints and loss of time optimality caused by direct smoothing, a strategy of smoothing with fixed minimum feed rate areas and overlimit areas was proposed. The optimal model for smoothing feed rate curve with fixed areas was established, and the solution method was proposed. The smoothness, processing time, and constraints compliance of the feed rate curve before and after smoothing were tested by using MATLAB. The results indicate that the proposed method improves the smoothness of the speed curve while satisfying the constraints and retaining most of the time optimality, and the average jerk amplitude decreases by 16.37%, which is conducive to high-speed and high-precision processing.

Key words: NURBS interpolation; feed rate planning; curve energy minimization; high-order constraints; computer numerical control（CNC）machining