The Error Control Method Of Screw Rotor Based On Form Grinding

The screw rotor is the core part of screw compressor and its machining accuracy has a direct effect on the performance of screw compressor. Currently, form grinding has replaced milling as the main form for the finish machining of screw rotor. However, most domestic screw enterprises fail to grasp key manufacturing technologies for precision rotor grinding machine, which results in the fact that the machining error of rotors cannot be controlled and the machining accuracy cannot be guaranteed, consequently high price is paid to import machines from abroad. Therefore, it is of great significance to explore the error control method of form grinding screw rotor for the localization of the precision screw rotor grinding equipment.Funded by the National Natural Science Foundation of China (No.50975038), based on the research results of research team, this thesis researches the screw rotor form grinding principle and process, establishes the calculation and compensation model of divide error and profile error, proposes the processing method of rotor profile data and wheel data, develops the error control software of grinding screw rotor and verify the error control method by the actual data.First, this thesis studies the machining principle of cylindrical helical. Based on the theory of engagement, the contact condition formula of rotor helical surface and wheel revolution surface has been established. According to this contact condition formula, the reciprocal solving mathematical model of rotor profile and wheel profile has been set up. In order to determine the adjustment range of the grinding wheel installation parameters, this research further discusses the conditions that the rotor do not produce transitional surface and are not undercut.Second, the error control method of grinding rotor is proposed. On the basis of the analysis of the screw rotor form grinding process, the error control strategy that controls the divide error on rough grinding and profile error on finish grinding is presented. For the divide error, the error calculation model is established. The divide error is controlled by adjusting the grinding feed rate. As for the profile error, the error evaluation method is presented and the profile error is controlled via updating profile or dressing wheel.Third, the data processing method of rotor testing profile and dressing wheel profile is established. The noise points of the rotor testing profile data is removed by angle method. After that, the rotor testing profile data is smoothed by energy method of discrete points. The wheel dressing data is fitted by biarc spline fitting method. Finally, the main algorithms for calculation and compensation of the divide error and evaluation and compensation of the profile error are programmed by Matlab and then the grinding screw rotor error control software is developed, which has been tested. Meanwhile, the error control method is verified by using the actual machine data from rotor grinding machine TG350E.The grinding screw rotor error control method proposed in this thesis has a guiding significance and reference value for the improvement of the efficiency and precision of our domestic screw rotor machining..