Research On Reliability Of CNC Machine Tools And Rolling Functional Components

Functional reliability and accuracy retention are the key factors affecting the reliability of CNC machine tools.This article takes the National Science and Technology Major Project as the research background,and focuses on the analysis of the reliability of domestic CNC machine tools and its key functional components.Based on the data of field accuracy maintenance test,the accuracy maintenance efficiency of each feed system of the tested machine tool was evaluated,and the dynamic comprehensive error compensation of CNC machine tool was analyzed.The load transfer analysis of functional unit of the CNC machine tools is build and its load counting method is explored.We propose the load spectrum compiling principle of the CNC functional component,using variational mode decomposition algorithm for noise reduction of the load signals.Finally,this article extrapolates the short-term load spectrum based on the two-dimensional kernel function estimation method to obtains the full life cycle load spectrum,then make an 8-program loading spectrum.The specific research contents are as follows:(1)A reliability assessment model based on the small sample Bayesian with Markov Chain Monte Carlo method was established,and the fault data of CNC machine collected on the field experiment were analyzed to obtain the average failure-free working time of New Way machine tools.Moreover,we analyze the failure reason based on the field failure data,and propose some advices to improve the performance of domestic CNC machine tools.(2)The field accuracy maintenance test was carried out.According to the test data,the influential factors affecting the accuracy maintenance of the CNC were analyzed as follows:the running distance of each feed system and its applied loading.The accuracy retention efficiency of the samples was evaluated based on the data envelopment algorithm.The thermal error compensation of the feed system of CNC machine tool is analyzed.(3)The load transfer model of ball screws and linear guide of the vertical CNC machining center and horizontal CNC machine are established;The cutting force test system of vertical machining center and horizontal lathe were built.and the real-time load data is obtained through cutting simulation based on the processing data of the machine tool collected on the field experiment.The cutting load data is preprocessed and denoised based on adaptive variational mode decomposition algorithm(VMD)and Permutation entropy(PE).(4)Pointed out that the weakness of the traditional rain flow counting method,and determined the load counting method of functional parts based on load characteristics thinking of different cutting conditions,and illustrated with examples;Extrapolate the load spectrum using 2-D kernel function based on typical cutting process.Taking the typical workpiece machined in the field as an example,the load spectrum of rolling functional parts of CNC machine is compiled.