高速高精加工中的加减速控制

Method of Acceleration/Deceleration Control for High Speed and High Accuracy Machining

高速加工对数控机床加减速控制方法提出了更高的柔性、平稳性和位置精度要求。传统的段内加减速控制方法由于整体速度偏低,不能适应高速加工的需要。跨段加减速控制能使进给速度大幅提高,但在轨迹段尾和尖角过渡时产生过切现象。提出采用轨迹段尾速度预规划的方法可避免段尾速度突跳超限。在尖角过渡前,进给速度必须降到最大安全速度。通过轨迹预监控能及时发现尖角过渡,并规划好减速区间。另一方面,通过轨迹优化从根源上消除尖角过渡,可降低加减速控制的难度。

To implement high speed machining, the acceleration and deceleration control method of CNC machine tools must have better flexibility, stability and location accuracy. Conventional acceleration and deceleration control method plans velocity in single segment of machining path, so it can not meet the need for high speed. When acceleration and deceleration control strides segments, feed velocity can increase enormously. However, it is likely to bring too big velocity jump at the end points of segments, especially at place where the transition angle is very acuate. Too big velocity jump can lead to excessive cut. The velocity jump can be kept under limit by pre - planning velocity in the tail of segments. Feed velocity must decrease to a maximum safe value before crossing the sharp point. To ensure enough time for deceleration, it is necessary to find sharp- angled point in time. Transition angle acuity avoidance is another aspect of the problem, it may come true by adopting machining path optimization.