面向复杂零件加工的多轴联动数控机床几何误差补偿的研究

NC program modification method is an effective way to achieve high machining accuracy with low cost. For multiple machining features and huge data, it brings forward the new challenges for geometric error modeling, identification, and compensation method when facing complex parts machining program. This research will conduct on a 5-axis machining center with a tilting rotary table. The effort will focus on rotation axis error identification, geometric error and decoupling modeling, and complex NC program modification strategy. And the results in this study will provide valuable theory foundations for enhancing the machining accuracy of multi-axis machine. This research includes following contents: The selected geometrical quantity generated by the errors of the rotation axis is measured. Then an identification model including axis position and motion errors is established by the measured results. The error propagation in the identification process caused by the inaccuracy of the parameters in the model is studied, to find the influence rule of the accuracy of the error identification. Thus, the measurement method and procedure are developed according to the analysis results. Moreover, a model is proposed to evaluate the volumetric error variation of the machine caused by the every single error parameters. Hence, it can be applied to analyze the relationship between the value and variation of the parameter and the volumetric error distribution. Then the key error parameters can be recognized and then adopted to establish the error and decoupling model. In addition, the modification method and procedure for huge NC program sections is studied. For the different tool type and machining feature, the parts have variety of different requirements of the dimension, shape and location accuracy. Thus, the compensation mode templates including typical blank shapes and machining features can be created. Then the error compensation strategy can be developed with them. Finally, the on-line error compensation for complex parts machining program can be achieved with these research efforts.

数控加工程序修正的方法是提高数控机床加工精度的有效途径。在面对复杂零件加工程序时，多加工特征及巨量数据对几何误差建模、辨识以及补偿技术提出了新的要求。本项目以双转台五轴机床为研究对象，辨识旋转轴的几何误差，建立几何误差预测与解耦模型，构建复杂数控程序的识别与修正的补偿策略，为提高多轴机床加工精度提供理论依据。具体研究内容包括：测量综合反映旋转轴误差的几何量，建立轴线位置与运动误差的辨识模型，分析模型中各项参数的误差传递过程，揭示其对辨识精度的影响规律，确定测量的方法及规程；建立单项误差对空间误差影响程度的度量模型，分析其数值与变化规律与机床空间误差的相关性，确定建立误差预测与解耦模型的关键性误差源；研究巨量数控程序修正的方法及流程，分析刀具类型及加工特征对尺寸、形状位置精度的不同要求，建立典型毛坯形状与加工特征的补偿模式模板，构建误差补偿策略，实现复杂零件加工程序的在线误差补偿。

本项目开展了基于数控加工程序修正的多轴数控机床几何误差补偿研究。以双转台五轴数控机床为研究对象，围绕旋转轴误差辨识及误差补偿技术，面向复杂零件加工工艺，构建了复杂数控程序的识别与修正的补偿策略，实现了多轴联动数控机床误差在线补偿。.提出了基于球杆仪测量和辨识旋转轴轴线位置和运动误差的新方法。通过测量综合反映旋转轴误差的几何量，运用齐次变换法建立了旋转轴的几何误差模型，提出了基于两步法的轴线位置和运动误差综合辨识方法。同时引入了系数矩阵的条件数，分析了模型中各项参数的误差传递过程，揭示了安装参数及误差对辨识精度的影响规律，实现了安装参数的优化。设计了基于分段圆弧的测量轨迹，提出了球杆仪安装误差的校正方法，有效提高了测量和辨识精度。.研究了多轴轴数控机床关键性几何误差溯源的方法。采用均匀抽样的方法，对机床的工作空间进行离散，进而利用几何误差模型，获取离散空间节点处的刀位点位置与刀轴矢量误差序列与各项几何误差序列。引入Spearman秩相关分析模型，综合度量单项误差数值在总体空间误差中所占的比重，及其变化规律与总体空间误差分布的相关性，实现关键性几何误差的溯源。.研究了数控程序修正的方法及流程，根据刀具类型、加工表面对误差补偿模式的要求，建立了基于模板的在线数控程序修正的策略，有效减少了误差补偿计算量，提高误差补偿的效率，实现了复杂零件加工程序的在线误差补偿。同时，针对误差补偿过程中长轨迹的分段问题，提出了运用误差变化单调性以及基准转换的方法，分别实现直线、圆弧以及多轴联动直线轨迹分段，消除了多轴轨迹离散时的非线性效应的影响，有效地提高了误差补偿精度。.本项目面向复杂零件加工的多轴数控机床在线误差补偿的理论和技术，提出了旋转轴几何误差辨识的新方法，揭示了单项误差对空间误差的作用机制，构建了巨量数控程序识别和修正方法，可为通过误差补偿提高多轴数控机床的加工精度提供理论依据及实现方法。