The Collection And Compilation Of Cutting Force Load Spectrum Of CNC Lathe

As the core equipment of manufacturing industry,the quality and performance of CNC is directly related to the level of industrial modernization in a country.It can be said that it is the key to revitalize a country's manufacturing industry.At present,the research of CNC in our country mainly caters for high-precision,high-speed and high-grade multi-axis intermodal processing.Due to the lack of scientific and reliable load spectrum,the structure design of most of the domestic CNC lathe machine and the key functional components has employed the structure of imported CNC which makes it difficult to can get an accurate fatigue strength.For the same reason,most of the early troubleshooting tests for CNC before leaving factory is mostly the idle test or a simple loading test,which is an important reason for frequent failures,precision retention and low reliability of domestic machining centers.Therefore,it is of great significance to study the load testing technology and procedure preparation methods on load spectrum in order to guide the design of structure of CNC lathe and the reliability tests on functional components,which is effective to reach an improvement on the quality and performance of the domestic CNC lathe.In this paper,cutting force of CNC machine tools is studied.Through the comparison between field testing technology and laboratory testing technology,the latter approach has been adopted to obtain the cutting force.Based on the above,a great deal of load data was collected,and the method of preparing cutting force spectrum of CNC lathe was deeply researched.At the same time,the optimal solution of load spectrum distribution model was found by fuzzy comprehensive analysis,than,two-dimensional load spectrum is worked out.The main contents of this paper are illustrated as follows:Firstly,the acquisition of cutting load data is considered.Based on the analysis for the merits of the two methods for load acquisition,the laboratory measurement method is adopted.The principle,instrument and programs of experiment are discussed in detail.The cutting experiment is carried out,and the load of the CNC lathe is collected,which laid the foundation for the subsequent data analysis and the establishment of load spectrum.Secondly,the load spectrum of the CNC lathe is calculated.Through studying the routine method of load spectrum,and selecting the appropriate preparation method and preparation process according to the actual situation,the corresponding mathematical model is established to fit the load distribution.Through an analysis and comparison procedure,the rain flow enumeration is applied to count the load spectrum circularly.And the histogram of average amplitude as well as the table of the number of the two-dimensional average amplitude cycle are presented.Thirdly,the load distribution model is built and tested.Fitting parameters is performed on the histogram of average amplitude.It is found that Normal distribution,Gamma distribution and Weibull distribution all have an ability to reach a better fitting.The first step is to undertake a linear regression equation calculation.The second step is to estimate parameters.And finally,the obtained probability density function is used for fitting.The goodness test is conducted on fitting and parameter estimation by a common test of Kolmogolov(also known as K-S test).Finally,the life cycle extrapolation and application of load spectrum are presented.Because the multi-group cutting load obtained from the laboratory is still somewhat unilateral and single.It is preferable to use the life-span load spectrum to analyze the life and reliability of CNC machine tools.The average amplitude of the experimental data is superposed with the relative average amplitude and the relative number of cycles.And the load spectrum under the full life of the CNC lathe can be extrapolated.