Optimal Design Method Of Acceleration Test Scheme For NC Lathe Feed System Based On Inertia Force

CNC machine tools as the core manufacturing equipment of the manufacturing industry,has been the core product of industry concern.As the world’s largest machine tool consumer market,the reliability of domestic high-end machine tools still needs to be improved.Feeding system as the core of CNC machine tools,its reliability directly affects the quality of processed products,to carry out feed system reliability test is the necessary way to improve the reliability of the whole machine.In order to save cost,accelerated test can quickly find out the degradation or fault information of the feed system and get the attention of many industries.In order to rationalize the resources within the test,plan the test process in an orderly manner,and make the results of the accelerated degradation test of the feed system accurate and effective,it is necessary to carry out the optimization design of the accelerated degradation test of the feed system.This paper takes CNC lathe feeding system as the research object and focuses on the influence of inertia force on the feeding system.On the basis of analyzing the structure and degradation mechanism of the feed system,taking inertia force as the entry point,the optimized design method and simulation evaluation method for accelerated degradation test of CNC lathe feed system are proposed,and the effectiveness of the method is finally verified.The main research contents of this paper are as follows:(1)Considering the non-linear degradation characteristics of CNC lathe feeding system and inertia force,establish an accelerated degradation model and build a test bench.According to the analysis of the structure and principle of CNC lathe feeding system,the factors of its accuracy degradation and degradation mechanism are studied,the repeat positioning accuracy is selected as the degradation index according to the performance characteristics,the acceleration stress is determined with the inertia force as the research focus,the degradation threshold is selected according to the national standard and the characteristics of the feeding system,the acceleration degradation model of the feeding system based on the nonlinear Wiener process and inverse power law is established,and the acceleration degradation test rig of the feeding system is built.The accelerated degradation test rig was built.(2)Establish the optimization model for accelerated degradation test of feed system,carry out the mapping test,and evaluate the traditional scheme.According to the optimized design process and basic assumptions,refine and explain the test process and key links,determine the parameter estimation method of accelerated degradation model,construct parameter estimation formula,determine the optimization criteria,screen stress combination,sample size,testing interval and testing times as optimization parameters,and establish the optimized design model of accelerated degradation test of CNC lathe feed system with cost as the constraint.Based on the accelerated degradation test rig of the feed system,the mapping test of the feed system of CNC lathe is carried out,and based on the mapping test data,the model parameters are calculated,and then the traditional test program is evaluated.(3)Improve the differential evolution algorithm and solve the experimental optimization model,evaluate the optimization results,and carry out sensitivity analysis on the optimization results.Analyze the principle and advantages of the differential evolution algorithm,improve the operation method of the differential evolution algorithm based on the accelerated degradation model of the feed system,screen the parameters of the differential evolution algorithm and the model,establish the optimized design model of the accelerated degradation test of the feed system of CNC lathe based on the differential evolution algorithm,and use MATLAB software to solve it,and through the analysis of the results,derive the optimal test solution,and finally verify the high robustness of the test solution by The sensitivity analysis verifies the high robustness of the test scheme.(4)Evaluation of the test program based on Monte Carlo simulation.Considering the test conditions and economic situation,the simulation evaluation method of accelerated degradation test scheme of CNC lathe feeding system based on Monte Carlo simulation is proposed,and the mean value and standard deviation of the variance of the estimated mean time to failure of CNC lathe feeding system under normal working stress are selected as evaluation indexes to evaluate the traditional experimental scheme and the optimal test scheme,which proves the effectiveness of the method in this paper.