Abstract: Higher machining efficiency and smooth machining surface are two important objectives of the CNC machining. However, most of the spline real-time interpolation algorithms are developed based on the constraints of feedrate, resultant acceleration/deceleration, and resultant jerk. The maximum acceleration/deceleration ability of each machine axis is rarely included in the design process. Thus, a time approximate optimal real-time spline interpolation algorithm is proposed and it is geared to the demand of high-speed machining of CNC system. Based on the consideration of dynamic performance of the machine tool, our algorithm makes full use of the limits on the acceleration along each machine axis to achieve the approximate optimal machining efficiency in theory. Furthermore, three steps such as computing the velocity limited curve through pretreatment, velocity curve backward chaining and smooth processing are presented to compute the machining velocity curve. The computed velocity curve can satisfy the constraint conditions such as machining precision, the limits on the acceleration and jerk along each machine axis, which also smooth the machin surface in an efficient way. By the results of simulations, it show that the algorithm can greatly improve the machining efficiency. Meanwhile, it can achieve precision localization of the deceleration points and get a smooth machining velocity curve.

Key words: High-speed machining, Spline interpolation, Time approximate optimal, Velocity smooth