基于运动控制卡的PC数控进给速度前瞻控制

A Look-ahead Algorithm for Feed-rate Control in CNC with a Motion Control Card

为了解决在高速加工复杂轨迹时容易出现的工件过切和机床异常振动的问题,笔者提出了一种实时的进给速度前瞻控制算法。该算法在刀位点处假设一个虚拟小圆弧,用该圆弧的半径表示刀轨在该点的曲率半径,以该曲率半径计算加工小圆弧的最大许可速度,并作为该刀位点的最大进给速度。通过设定机床最大速度和最大加速度约束,对各段的进给速度进行整体规划,并结合运动控制卡的特点,对段内进行速度处理,最大限度地提高加工效率。仿真结果表明:该算法能够实现实时前瞻速度控制。

A real time software control algorithm for look-ahead feed-rate control was proposed in this paper to solve the problem of gouging and mechanical vibration caused by complex tool path in high speed machining. An assumptive arc was used to contour two adjoining segments of tool path. The radius of the small arc was used to express the curvature radius of the tool path on this cutter location point, and the feed-rate on the cutter location was limited through limiting the maximum speed of the small arc. The real time look-ahead algorithm was used to programme the feed-rate of the total tool path on the restriction of the maximum feed-rate and acceleration of the machine. The inside feed-rate of segments was also prograrmned to adapt to the feature of the motion control card. All the programming was based on ensuring the maximum efficiency in machining. The simulation result indicates that this algorithm was practical and can be easily realized.