| Summary: | 碩士 === 國立雲林科技大學 === 機械工程系 === 107 === The linear axis is the basic equipment of the machine tool. The quality of the linear axis will directly affect the overall performance of the machine. The condition of the machine tool can be revealed by positioning accuracy detection, but the commercial testing equipment is expensive and hard to operate. However, the detection and calibration are more cumbersome for five-axis machine tool because of the rotating shaft. Therefore, a positioning error detection method for a linear axis (Y-axis) and a rotation axis (C-axis) will be constructed to improve the efficiency of the detection and accuracy of the machine tool.
In the study, the self-developed Fabry-Pérot laser interferometer is used to measure the linear axis, and the optical axis automatic alignment system has been constructed. The optical axis in the interferometer would be aligned to the linear axis by the program of the automatic alignment system. It took an average duration of 53 seconds to complete the optical axis adjustment procedure and the cosine error can be reduced to 1 nm in the stroke of 120 mm. As regards rotary measurement, the fine adjustment fixture has been assembled for the steel ring of the angle encoder. By the fixture, the run-out and axial tilt between the steel ring and the rotating shaft can be regulated, and the time required for setting up the angle encoder can be decreased. In addition to enhancing the measurement efficiency, the errors during setting up the instrument are also reduced with the aid of the fine adjustment fixture, so that the accuracy of the measurement result is more reliable.
The dual-axis simultaneous motion error measurement system has been constructed by integrating linear and rotary axis detection systems. Through the dual-axis simultaneous motion mode, a cross-sectional profile can be processed. In this study, there are three different testing contours. The difference in the trend line of the contour error would be observed with the different feed rates. Based on the radius error corresponding to each angle, the coordinate correction of the path is performed. After the coordinate compensation of the numerical control code, the experimental results indicate that the maximum contour error of the cam is reduced from 18.8 μm to 9.5 μm, that of the parabola is reduced from 25.7 μm to 12.4 μm, and that of the ellipse is reduced from 18 μm to 9.8 μm. At last, the accuracy and feasibility of the dual-axis simultaneous motion measurement system have been verified by the actual cutting specimen of aluminum alloy.
Keywords: optical axis automatic alignment、linear axis、rotary axis、dynamic simultaneous measurement、contour error compensation
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