| CNC machine tool is the infrastructure of modern manufacturing industry.As a very important functional part of CNC machine tool,the low reliability of double power servo turret has become a key factor limiting the development of CNC machine tool.Therefore,in order to improve the reliability of CNC machine tool,one of the necessary links is to improve the reliability of servo turret,which plays an indispensable role in ensuring the stability of CNC machine tool operation and improving the maintenance efficiency of the machine tool in the later period.This paper mainly studies the reliability modeling and analysis method of the double power servo turret of CNC machine tools and analyzes the fault data of Yantai Huanqiu AK33100D double power servo turret with examples.The research contents are as follows:(1)The reliability analysis of double power servo turret is carried out.The failure data of Yantai Huanqiu AK33100D servo turret are processed by FMEA,the servo turret system is divided and each failure mode is analyzed.The severity of the tool rest system is obtained,and then the hazard level sequence of subsystems affecting the servo turret reliability is obtained.The results show that the two subsystems with high fault severity are the cutter head signal device and the sealing and fastening device,which lay the foundation for the subsequent reliability modeling and distribution.(2)The reliability model of double power servo turret is established.According to the field test data of the servo turret,the parameters are estimated by the least square method and tested by the correlation coefficient method,so as to establish the mathematical distribution model of the fault interval time of the servo turret.The results show that the failure interval time of servo turret obeys Weibull distribution with shape parameter of 0.7461 and scale parameter of 6351.6320.The MTBF point is estimated to be 7593.3761 hours and the bilateral interval is estimated to be[6629.77,8605.72]hours.(3)This paper presents a reliability analysis method based on Fault Tree Monte Carlo simulation.Build the fault tree of the double power servo turret system,determine the minimum cut set of the basic events of the fault tree,verify the distribution type of all bottom event fault data and calculate its eigenvalue.Fault Tree Monte Carlo simulation is carried out by using MATLAB,and the reliability of servo turret is estimated by combining function relation,then compared with MTBF obtained by traditional reliability analysis method.The results show that the MTBF of servo turret is stable at 7236.72 hours,and the error is only 4.69%compared with the MTBF calculated by the classical algorithm,which verifies the correctness of the simulation results.To solve the problem of low randomness,difficulty in processing and slow operation caused by the long test period and insufficient data samples of traditional reliability analysis.(4)Reliability distribution and growth technology management of double power servo turret.The method of combining interval analysis,analytic hierarchy process and fuzzy comprehensive evaluation is used to allocate the reliability of servo turret,and interval number is used to represent fuzzy information,so as to solve the problem of uncertain value when a single allocation method is used to represent the fuzzy factor index,and make the allocation result more reasonable.The results show that the existing reliability level of the servo turret fastening and sealing device,the servo turret signal device and the positioning and clamping device is lower than the assigned value,so reliability management is carried out in the design,manufacturing and use stages to improve the reliability of the servo turret. |
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