Research On Reliability Evaluation Method Of CNC Gear Hobbing Machine Based On Fuzzy Analytic Hierarchy Process

Since the founding of new China,China has built an independent and complete industrial system.As the necessary guarantee for industrial development,equipment manufacturing industry has always been the focus of the industry.As an indispensable part of equipment manufacturing industry,CNC machine tool has become an important guarantee for national defense and industrial safety.As its core competitiveness,the reliability of CNC machine tool has become an important topic in the academic field and even in the industry.With the large gear in the ship,power and other industries,the CNC gear hobbing machine for manufacturing and processing large gear also put forward higher requirements.This paper mainly studies the evaluation method of CNC gear hobbing machine,and the main research contents are as follows:(1)The fault data acquisition and reliability modeling of CNC gear hobbing machine are carried out.According to the characteristics of CNC gear hobbing machine,the timing tail cutting test scheme is selected to collect data,and the parameters are estimated by least square method.The fitting curve of single Weibull distribution is obtained and the difference between data points and fitting curves is found to be large,and then the fitting curve is basically in accordance with the data point by using the mixed Weibull distribution of two parts.The estimated MTBF of CNC gear hobbing machine is 317.0117 hours.(2)The reliability of CNC hobbing machine is analyzed.FMEA is used to process the fault data of CNC gear hobbing machine,and the subsystem of CNC gear hobbing machine is divided.The fault location and fault mode of the whole machine are analyzed.The fault mode and fault cause of three subsystems with high fault rate are analyzed,and the system harm degree is obtained,Then,the order of subsystem hazard degree which affects the reliability of CNC hobbing machine is obtained.The results show that the hazard degree is much higher than the other three subsystems,which are electrical system,spindle components and hydraulic system.(3)A reliability allocation method based on improved fuzzy analytic hierarchy process is proposed.Taking the hydraulic system as an example,two experts are asked to give the weight fuzzy complementary judgment matrix by the method of expert scoring.By transforming and synthesizing the opinions of the two experts,the weight vector of the hydraulic system and the ranking vector of various factors can be obtained.Finally,the overall ranking of the hydraulic system can be obtained.It is concluded that the complexity of the oil circuit of the machine tool is high and the reliability is low,The complexity of the oil supply station is low and the reliability is high.(4)A joint modeling method of reliability growth planning considering the cost performance of product life cycle is proposed.The optimal product release time and reliability growth test resource allocation are determined by minimizing the product life cycle cost.A numerical example is given to illustrate the key modeling method.Compared with the traditional reliability growth planning method in terms of product release time,reliability and cost,the joint modeling method can obtain the optimal release time and the lowest product life cycle cost under the acceptable condition of product reliability reduction.