Intelligent Matching Methods of Five-Axis Machine Tools Position Loop Gains for Parts Contouring Accuracy
LÜ Dun1, ZHAO Yufei1, LIU Shuo1, SUO Qi2, LIU Hui1, ZHANG Huijie1
1. School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710054, China;
2. Genertec Machine Tool Engineering Research Institute Co., Ltd., Beijing 101312, China
五轴机床加工复杂曲面零件时,由于加工路径曲率大、进给加速度大等原因,零件轮廓精度难以控制。本文基于五轴机床轮廓误差与各轴位置环增益的显函数关系,提出五轴机床联动轨迹精度的智能控制流程。通过“自我感知”各轴指令位置与跟随误差、“自我分析”联动轨迹轮廓误差超差位置、“自我决策”最优轮廓误差及对应位置环增益,为不同零件配置专属增益,从而保证复杂曲面零件加工精度。KMC400U五轴立式加工中心各轴位置环增益为(70,70,80,70,75),为S 形试件直纹面A配置专属增益(70,68,80,59,70)后,最大轮廓误差降低了43.75%;为叶轮小叶片吸力曲面配置专属增益(40,70,48,40,75)后,最大轮廓误差降低了28.57%。S试件直纹面A和叶轮小叶片吸力曲面的专属增益的计算时间分别为38.4 s 和5.7 s,可满足工程应用要求。
When machining complex curved parts on five-axis machine tools, due to factors such as the large curvature of the machining path and high feed acceleration, the tracking error of each axis cannot be controlled to be sufficiently small, resulting in difficulties in controlling the contouring accuracy. Coordinating the tracking error of each axis by matching servo gains emerges as a potential approach. However, existing gain solution methods are complex and time-consuming, rendering them inapplicable to actual production. In this paper, based on the explicit functional relationship between the contour error and the position loop gain (PLG) of each axis, a dynamic matching model for the PLG is established, and an intelligent control process for the linkage trajectory accuracy is proposed. Throug h “selfawareness” of the setpoint position and tracking error of each axis,“ self-analysis” of the position where the contour error of the linkage trajectory exceeds the limit, and“ self-decision” of the optimal contour error and the corresponding PLG, this intelligent control process can configure exclusive gains for different parts to ensure the machining accuracy of complex curved parts. For the KMC400 five-axis vertical machining center, the PLG of each axis is (70, 70, 80, 70, 75). After matching the exclusive gain (70, 68, 80, 59, 70) for the ruled surface A of the S–shaped test piece, the maximum contour error is reduced by 43.75%; after matching the exclusive gain (40, 70, 48, 40, 75) for the suction surface of the small blade of the impeller, the maximum contour error is reduced by 28.57%. The calculation time for the exclusive gains of the ruled surface A of the S–shaped test piece and the suction surface of the small blade of the impeller is 38.4 s and 5.7 s, respectively, meeting engineering application requirements.