Prediction and compensation of machining geometric errors of five-axis machining centers with kinematic errors
Prediction and compensation of machining geometric errors of five-axis machining centers with kinematic errors
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DOI：
10.1016/j.precisioneng.2008.06.001
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发表时间：
2009-04
影响因子：
3.6
通讯作者：
S. Uddin;S. Ibaraki;A. Matsubara;T. Matsushita
中科院分区：
文献类型：
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作者：
S. Uddin;S. Ibaraki;A. Matsubara;T. Matsushita
由于五轴加工中心中的几何不准确而引起的运动误差导致刀具位置和定向偏离命令值，这因此影响加工表面的几何精度。如机床工业中众所周知的，如NAS979标准中规定的对截头圆锥体的加工是五轴加工中心的广泛接受的最终性能测试。然而，这种加工测试的一个关键问题是，机床的误差源对加工的圆锥截头体的几何精度的影响没有被机床制造商完全理解，因此很难找到加工误差的原因。针对这一问题，考虑运动误差对刀具和工件三维干涉的影响，提出了一种五轴联动加工几何误差仿真器。本文首次采用DBB法对可倾转工作台五轴加工中心的运动误差进行了辨识。使用加工中心的误差模型与识别的运动误差，并考虑工件的位置和几何形状，加工几何误差相对于工件的标称几何形状的预测和评估。为了提高加工表面的几何精度，还提出了一种刀具位姿误差补偿方法。最后，作为一个例子，加工锥台通过使用直立铣刀，如标准NAS979中所描述的，被认为是在案例研究，以实验验证的预测和补偿的加工几何误差在五轴加工。
Kinematic errors due to geometric inaccuracies in five-axis machining centers cause deviations in tool positions and orientation from commanded values, which consequently affect geometric accuracy of the machined surface. As is well known in the machine tool industry, machining of a cone frustum as specified in NAS979 standard is a widely accepted final performance test for five-axis machining centers. A critical issue with this machining test is, however, that the influence of the machine's error sources on the geometric accuracy of the machined cone frustum is not fully understood by machine tool builders and thus it is difficult to find causes of machining errors. To address this issue, this paper presents a simulator of machining geometric errors in five-axis machining by considering the effect of kinematic errors on the three-dimensional interference of the tool and the workpiece. Kinematic errors of a five-axis machining center with tilting rotary table type are first identified by a DBB method. Using an error model of the machining center with identified kinematic errors and considering location and geometry of the workpiece, machining geometric error with respect to the nominal geometry of the workpiece is predicted and evaluated. In an aim to improve geometric accuracy of the machined surface, an error compensation for tool position and orientation is also presented. Finally, as an example, the machining of a cone frustum by using a straight end mill, as described in the standard NAS979, is considered in case studies to experimentally verify the prediction and the compensation of machining geometric errors in five-axis machining.