Research On The Rotating Accuracy Measurement Instrument For Rotary Table Of (5-axis) Numerical Control Machine

The precision detection of the operating floor of a numerical control machine is a key factor in the mechanical processing industry, the processing accuracy could not be guaranteed unless the positioning accuracy of the numerical control machine is assured. Different kinematical axes need different detection methods, till now the linear axis and the backspin axis have good detection methods but the detection of the pitch axis is quite difficult and without any proper detection equipment. The aim of this paper is to find a machine that could accurately detect the backspin axis and the pitch axis and to provide some meaningful suggestions in this aspect.In the first place, the basic principles of some optical methods to measure angles are introduced and their advantages and disadvantages are analyzed, some methods to measure the five axes of the numerical control machines simultaneous are discussed. Some other methods are considered in terms of practicality and accuracy. After careful analysis, we find each method has some difficulty that could not overcome. Owing to a wide rang of advantages for laser gyro to measure angles, a method using laser gyro to detect the accuracy of the numerical control machine is proposed.In the second place, according to the operating principles and characteristics of laser gyro, the decision is made using laser gyro to measure the accuracy of the operating floor. The dithered ring laser gyro is chosen in a wide rang of laser gyro products and the aim of the detection accuracy is one arcs, all following research is centered on this aim. To begin with, the effects of all kinds of errors are theoretically analyzed and the relevant accuracy demand for those parameters is proposed, then some experiments are carried out according to those problems and finally resolved them. The revolution accuracy detection equipment which center's on the laser gyro is devised and the detection of the backspin axis and the pitch axis are realized. The effects of the earth's rotation and the null-shift on the measurement are analyzed, the counting method which is used to judge the rotating table is properly working or not according to the setup rang comparison of the pulse, it is simple, accurate and achieved good results. In terms of the site calibration problem, an on-line scale factor measurement method is proposed. A Labview software is programmed which could eliminate the effects of the earth's rotation and the null-shift, on-line scale factor measurement and the angle detection.Finally, the equipment using XJ367 and D674 laser gyro to measure the backspin axis and the pitch axis of the numerical control machine are carried out respectively. Owing to the instability and low accuracy of XJ367, its'accuracy did not reach one arcs. However, the measure results of high stable and accurate D674 realized the less than one arcs aim with good repeatability and reliability. Compared with the measurement results of ML10 laser interference system, the largest error is 0.78 arcs, which also proving that the accuracy of the devised equipment is less than one arcs.