The Accuracy of Machine Tool Motion at Nanometer Level and Its Transfer Fidelity to Machined Surface

本研究的目的是开发一种改进的机床元件运动精度的测量方法，并分析机床运动对加工表面轮廓的传递保真度。在对三点法进行分析的基础上，提出了一种评估空气主轴转子径向跳动的新方法。该方法可以在不使用常规参考球的情况下获得转子的真实跳动信息。利用新研制的亚纳米分辨率反射式光电位移传感器，在30 <mu> m工作范围内，对空气主轴的跳动进行了评价。所测空气主轴的旋转精度在50nm左右，重复性小于2nm。在此基础上，以激光束为直线度基准，提出了以纳米分辨率评价机床元件直线运动精度的方法。该方法的原理是对固定在运动物体上的四象限光电二极管中心的位移进行高灵敏度检测，该四象限光电二极管作为激光束的目标。利用所提出的方法，测量和分析了气动滑块和特殊设计的弹性铰链在强制变形作用下的直线运动精度。成功地测量了空气滑块的直线运动精度在0.1 <mu> m数量级，在小于100 <mu> m的短距离运动中，测量了弹性铰链的误差运动小于1nm。利用上述机床元件进行了一系列的切削实验，并对其表面轮廓进行了分析。在用金刚石工具车削时，观察到黄铜特定晶粒表面的形状精度小于2nm。结果表明，机器运动到加工表面的传递保真度约为1nm。少

The purposes of this research are to develop a improved measuring method of the accuracy of motion of machine tool elements and also to analyse the transfer fidelity of the machine motion to the profile of machined surface.Based on an analysis of the so-called 3-points method, a new method is proposed for evaluating the radial runout of the rotor in an air spindle. The information on the true runout of the rotor can be obtained by this method without using the conventional reference sphere. With the aid of the newly developed reflective photo-electronic displacement sensor with subnanometer resolution and about 30 <mu> m working range, the runout of the air spindle is evaluated by the method proposed. The air spindle tested is shown to be operated within the rotational accuracy of about 50nm with the repeatability of less than 2nm.Furthermore, using the laser beam as a datum of straightness, the method is proposed for evaluating the accuracy of straight motion of machine tool elements … More with nanometer resolution. The principle of the method is high-sensitive detection of the displacement of the center of quadrunt photodiode which is fixed to the moving object and acts as a target of the laser beam. By employing the method proposed, the accuracy of straight motion on air slide and a specially designed elastic hinge subjected to forced deformation are measured and analysed. The accuracy of the straight motion of an air slide is successfully measured to be at the order of 0.1 <mu> m. In the short range of movement less than 100 <mu> m, the error motion of the elastic hinge is measured to be less than 1nm.Employing the machine elements as above, a series of cutting experiments was carried out and the surface profile is analysed. The form accuracy of the surface is observed to be less than 2nm in a specific crystal grain of brass when turned by a diamond tool. This results shows that the transfer fidelity of the machine motion to the machined surface is considered to be about 1nm. Less