考虑主轴-刀柄结合面特性的机器人铣削系统刀尖频响预测研究

Research on Tool Tip Frequency Response Prediction of Robot Milling Systems Considering Characteristics of Spindle-toolholder Interface

针对机器人铣削系统刀尖频响具有位姿依赖特性,导致机器人变位姿加工时稳定性难以准确预测、加工颤振难以有效控制的问题,提出一种考虑主轴-刀柄结合面接触刚度的机器人铣削系统刀尖频响预测方法。基于欧拉拉格朗日法与吉村允孝单位面积法,分别构建了机器人本体动力学模型与主轴-刀柄结合面接触刚度模型,进而基于有限元主副自由度理论将机器人本体动力学模型与主轴-刀柄结合面接触刚度模型结合,构建了机器人铣削加工系统刀尖频响预测模型。开展了机器人不同位姿下刀尖频响预测验证实验,结果表明,仿真与实验得到的刀尖频响函数相比,固有频率最大误差为6.63%,对应幅值最大误差为9.80%,验证了所提出的预测模型的准确性,证明了该模型能够实现机器人任意位姿下的频响函数准确预测。

Aiming at the problems that the tool tip frequency response of robot milling systems was posture-dependent,which made it difficult to accurately predict the stability and effectively control the machining chatters in the process of robot pose changing,a prediction method of the tool tip frequency response of robot milling systems was proposed considering the contact stiffness of spindle-toolholder interface.Based on Euler-Lagrangian method and unit area method of Yoshimura,the dynamics model of robot body and the contact stiffness model of spindle-toolholder interface were constructed,respectively.Then,based on the theory of the main and auxiliary degrees of freedom of finite element,the dynamics model of robot body and the contact stiffness model of spindle-toolholder interface were combined to construct the prediction model of tool tip frequency response of robot milling systems.The verification test of tool-tip frequency response prediction under different postures of the robot was carried out.The results show that the maximum error of the natural frequency is as 6.63%and the maximum error of the corresponding amplitude is as 9.80%compared with the frequency response function of tool-tip obtained by simulations and experiments,which verifies the accuracy of the proposed prediction model and proves that the model may realize accurate prediction of frequency response function under any postures of the robot.