A real-time and look-ahead interpolation methodology with dynamic B-spline transition scheme for CNC machining of short line segments

Abstract

Tool path is presented as continuous small line segments in some existing NC machining programs. To achieve high machining speed and smooth machining quality, the tool path needs to be processed. This study presents a real-time and look-ahead interpolation methodology with dynamic B-spline transition scheme for short line segments machining. In the methodology, transition curve is adjusted to avoid intersection and keep high machining speed. Firstly, the unit length of every B-spline transition curve is calculated depending on tool path and NC system requirements; then, the maximum allowable velocity of the curve which is called threshold velocity can be got. Secondly, transition curve is determined according to the unit length and two consecutive threshold velocities, and time optimization function makes the transition curve take less machining time. Thirdly, the 7-phase velocity planning algorithm and static look-ahead algorithm are adopted to generate smooth machining feedrate and fine machining quality. Lastly, the curve interpolation is performed on the processed tool path. The simulations and experiments demonstrated that the proposed algorithm is able to achieve high machining speed and generate fine machining quality.