Abstract: To satisfy the need of high speed machining, assumptive arc is used to contour two adjoining moves together on the corner to make smooth paths, the radius of small transit arc can be adjusted with contour accuracy, and the federate on the corner can be limited through limiting the maximum speed of small arc. A look-ahead algorithm of series of moves is proposed for the process of speed adjustment in advance, which avoids the occurrence of overload of cutter tool on the corner and reduce the servo track error of part on the corner or of small arc move. Equivalent trapezoidal velocity profile is used to analyze the speed of S-curve velocity profile and work out the accurate interpolation method of S-curve velocity profile which overcomes the disadvantage of looking up table to calculate federate speed approximately, thus high resolution and fine surface quality can be obtained while machining speed is high. The algorithm is effective and has been adopted by CNC system of newly developed high-speed milling machine.

Key words: CNC, feedrate smoothing, transit circular arc, S-curve velocity profile, high speed machining