Research On The Law Of Declining Of The Comprehensive Performance Of CNC Turret Tool

The comprehensive performance of the CNC turret directly determines the machining capability of the CNC turret.Through theoretical analysis and combined with the previous research results,the four indexes of repeated positioning accuracy,stiffness,cutting vibration and indexing noise have the greatest influence on the CNC turret performance.The improvement of the process ability of CNC turret will bring about the improvement of the reliability of CNC turret,and the improvement of the reliability of CNC turret is the key step for indigenous CNC turret to realize to surpass the quality of imported CNC turret.The decline of process ability of CNC turret is inevitable because of the increase of load progress.Due to the lack of the current theory of precision reduction of CNC turret and the method to accurately estimate the true performance and precision retention time of the CNC turret during the structural design stage,it is difficult for the design,repairing and the reliability estimation of product to describe the decline process of CNC turret accurately under real working conditions.In order to solve these problems,the research on the performance and precision retention of the CNC turret based on the test data from processing department of the enterprise.In order to obtain the degradation process of performance and accuracy under the real working conditions of the CNC turret,under the support of special fund project for major scientific and technological achievements in research and capacity building on test common technology of functional component,it is carried out to go to the machine tool user enterprise to collect the field test performance and the accuracy parameter changing data of the CNC turret.The data of four comprehensive performance indicators of CNC turret is collected five times through the laser displacement sensor and some other equipments.This paper mainly studies the retention evaluation of the comprehensive performance of CNC turret,the retention evaluation of repeated positioning accuracy of CNC turret,and the reliability evaluation of reliability in the presence of sudden failures and degraded failures through orthogonal test sampling,the analyzed cutting vibration signal in the time-frequency domain,accuracy retention theory,AHP method and reliability technology.The contents in this paper can be organized as follows:1.According to the national standards and related theoretical research results,the reason to choose repeated positioning accuracy,axial stiffness,cutting vibration and indexing noise as the evaluation index of the comprehensive performance of CNC turret is explained.On this basis of these,the test program for the data of repeated positioning accuracy,axial stiffness,cutting vibration and indexing noise of the CNC turret is established.The test requirement and procedure of four comprehensive performance indicators is also stipulated.2.The laser displacement sensor,jack,accelerometer and noise meter are selected as the data acquisition equipment for repeated positioning accuracy,stiffness and indexing noise,and the detection principle and detection method of each equipment are expounded.Using the method proposed in this paper,the variation trend of the parameters of the four indicators of the tested CNC turret in 192 days is analyzed.A controlled test of the field position of the indexing noise and the position of the national standard is designed,and the field test data is corrected.3.The typical cutting process parameter profile of the CNC turret is determined by orthogonal table sampling and the cutting vibration signal is collected.On this basis,the time-frequency domain analysis of the cutting vibration signal,the surface roughness of the components is detected,and the correlation analysis between the eigenvalue and the roughness value of the vibration signal is carried out,and the eigenvalues of the systematic error and random error in the test are analyzed.4.The machine precision retention theory is applied to the comprehensive performance evaluation of the CNC turret,and the results of repeated positioning accuracy,axial stiffness and index noise index retention are evaluated.According to the 3σ principle,the root mean square value of the cutting vibration is evaluated.The analytic hierarchy process is used to quantify the weights of the four indicators.For the repetitive positioning accuracy with the largest weight,the Regress toolbox of regress analysis and the least squares method are used to estimate the time of the recursive positioning degradation of the test CNC turret.Finally,the reliability calculation method of CNC turret under the condition of repeated failure accuracy and reliability failure caused by sudden failure competition is proposed.