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

点击翻译按钮获取中文摘要

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