Reliability Analysis Of Accuracy And Optimization Design Of Process Parameters For Five-Axis Milling

As one of the ten important fields of manufacturing development,the continuous improvement of CNC machine tool processing level plays a vital role in the construction of manufacturing power.The machining precision of CNC machine tool is one of the important indexes to measure the performance of machine tools.As an important part of the CNC machine tool processing system,the wear of tools leads to poor machining accuracy and low reliability,which restricts the performance of CNC machine tools.Therefore,it is of great significance to carry on the reliability analysis and the optimization design of the machining process parameters for the milling machining precision of CNC machine tools.Aiming at the process of difficult-to-cut materials for five-axis CNC machine tools,this paper has carried out four aspects of tool wear modeling,accuracy reliability modeling of five-axis milling machining,accuracy reliability analysis and reliability optimization design of machining process parameters,the specific research contents are as follows:(1)Aiming at the tool wear process with a high-dimension parameter,small sample,and high nonlinearity,this paper considers the influence of machining process parameters on tool wear,and designs orthogonal test with machining process parameters as variables.The tool wear test data were obtained by using the method of map measurement,and the tool wear model was established by Gaussian process,and the correctness of the tool wear model was verified by comparing the measured value of tool wear with the predicted value.(2)There are many errors in the processing process to affect the machining accuracy of CNC machine tools,such as machine tool motion error,tool wear error,tool manufacturing error and so on.In this paper,the machining system of LU-400 five-axis CNC machine tool was taken into account,the errors in machining were fully considered,the correlation between low sequence bodies was expressed according to multi-system theory and homogeneous coordinate transformation,and the reliability model of five-axis milling accuracy was established scientifically and rationally.(3)Aiming at the static error and dynamic error in the process of five-axis milling,The single-loop Kriging surrogate modeling for time-dependent reliability analysis method based on parallel learning function was proposed to analyze the accuracy reliability of five-axis NC milling machining.According to the calculation results,the trend of accuracy reliability of five-axis milling with time is obtained.(4)With machining efficiency as the optimization object and reliability of machining accuracy and tool life as the constraint condition,the model of reliability-based optimization design was proposed.The single-loop Kriging surrogate modeling for time-dependent reliability analysis method based on parallel learning function was used to solve the reliability value,and the sequential quadratic programming method was used to obtain the optimum process parameters.After the optimization design of the process parameters,the machining efficiency is improved by 11.10%,the reliability of machining precision and tool life reaches 99.29% and 42.37 min respectively.Based on the reliability analysis of five-axis milling accuracy and the optimization design of machining process parameters,the machining efficiency of difficult-to-cut materials is improved under the requirements of reliability of machining accuracy and tool life,which provides a theoretical guidance for the selection of process parameters of NC milling.