Research On The Parameters Of The Instantaneous Milling Force Model Of The Variable Cross-section Scroll Plate And Its Experimental Verification

Scroll is the core part of scroll compressor,and its machining accuracy directly affects the reliability and working efficiency of scroll compressor.Milling force is an important physical quantity in the process of scroll plate manufacture,which is closely related to the machining quality,machining efficiency and milling tool wear.The establishment of a high-precision mathematical model of instantaneous milling force can lay a mechanical foundation for the research of machining quality such as milling chatter of the variable cross-section scroll plate.However,due to the effects of tool runout,chatter,surface roughness and other factors,there are some problems in the current instantaneous milling force model of scroll plate,such as low accuracy,the selection of milling parameters depends on empirical methods and so on.Therefore,considering the factor of tool runout,this thesis establishes the prediction model of the instantaneous milling force of the variable cross-section scroll plate based on the machining experiment,and studies the influence of milling parameters on the milling force coefficient.The main contents are as follows:(1)Experimental study on milling of variable cross-section scroll plate.According to the principle and method of forming the scroll profile,the profile equations of the inner and outer wall of the three-stage base circle involute are established,and the two-dimensional and three-dimensional models of the three-stage base circle involute are established by CAD and SolidWorks software.Based on the orthogonal experimental method,the milling experiment scheme of variable cross-section scroll plate is designed,and the milling of variable cross-section scroll plate is completed on XK714 CNC milling machine.The kistler9257b three-way piezoelectric force measuring instrument is used to record the instantaneous milling force data with different milling parameters changing with time,and the data are analyzed and transformed into the instantaneous milling force data with the change of tool rotation angle,which lays the experimental foundation for the follow-up research work.(2)Parameter solution of instantaneous milling force model of variable cross-section scroll plate based on improved particle swarm optimization algorithm.In order to improve the prediction accuracy of the instantaneous milling force of the variable cross-section scroll plate,the mathematical model of the instantaneous milling force of the variable cross-section scroll plate is established by theoretical derivation.The improved particle swarm optimization algorithm with adaptive inertia weight and random disturbance factor is used to identify the instantaneous milling force coefficient and tool run out parameter of the variable cross-section scroll plate synchronously.Combined with the experimental data of the instantaneous milling force of the variable cross-section scroll plate,the peak error of the measured and predicted curves of the instantaneous milling force is less than 15%,which shows that the improved particle swarm optimization algorithm can provide the basis for the prediction of the instantaneous milling force with the consideration of the tool runout,and this method only needs a few experiments to get a high accuracy parameter identification result,reduces the experimental cost,improves the prediction accuracy of the instantaneous milling force of the variable cross-section scroll plate,and has an important reference value for the processing of the scroll.(3)Analysis of the influence of milling parameters of variable cross-section scroll plate on the average milling force coefficient based on multiple regression method.In order to study the influence of milling parameters on milling force coefficient,the instantaneous milling force coefficient of variable cross-section scroll plate is assumed to be constant,and the calculation formula of the average milling force coefficient is derived from the instantaneous milling force model.In this thesis,the instantaneous milling force data with the change of tool rotation angle is treated as the average milling force data by using the definite integral method.Based on the data,the average milling force coefficient values of the variable cross-section scroll plate under different milling parameters are calculated.Four different regression models are used to carry out multiple regression analysis on the average milling force coefficient in the tangential and radial directions respectively.The final regression model of the average milling force coefficient is selected by the p value of F test and the judgment coefficient R~2.Compared with the milling experimental data,the results show that the relative error of the regression model of the average milling force coefficient in tangential and radial direction is controlled within 20%,which shows that the regression model can provide a basis for the study of the influence of milling parameters on the average milling force coefficient.Finally,the influence of four milling parameters on the average milling force coefficient is studied.It is found that the influence of the depth of cutting and the amount of side cutting on the tangential average milling force coefficient is relatively large and shows a non-linear relationship.The influence of the feed per tooth and the tool rotation speed is small,showing a linear relationship and tends to be horizontal.However,the radial average milling force coefficient has a linear relationship with the depth of cutting,the feed per tooth and the amount of side cutting,and increases with the increase of the independent variable,and the influence of the tool rotation speed on it is relatively small.This study provides a reference for the selection of milling parameters of variable cross-section scroll plate.