Reliability Evaluation Of Motorized Spindle Based On No-Failure Data

Today,with the rapid development of industrial information technology,high-end CNC machine tools,which are the "mother of industry",have become the cornerstone of the development of the manufacturing industry.The performance and reliability of the motorized spindle as its key performance component has also become a key factor restricting the development of high-end CNC machine tools.Considering the long life characteristics of the motorized spindle itself,it is difficult to obtain the failure data for traditional fault modeling.Therefore,how to design the accelerated degradation experiment of the motorized spindle and evaluate the reliability of the motorized spindle based on the failure-free data has become one of the hot research issues in the current academic circles.In this paper,a certain type of CNC machine tool motorized spindle is used as the main research object.According to the certain fault data obtained by the cooperation factory in the previous stage,the structural division and fault analysis of the motorized spindle are carried out,and the accelerated degradation test device of the motorized spindle is designed and tested.The construction of the platform,and then select the motorized spindle to accelerate the accelerated stress test of the degradation test and the corresponding test time for testing.Finally,a reliability evaluation method for motorized spindle based on no-failure data is proposed.Firstly,according to the working principle and structure of the motorized spindle,the subsystem division of the motorized spindle is completed.Based on the fault data collected by the previous cooperative factory,the failure mode and the damage analysis(FMECA)method are used to develop the corresponding fault data.Based on the analysis,the key subsystems of the motorized spindle and the key failure modes are determined based on the PageRank algorithm.Then,according to the field fault data and the processing flow chart,the cutting force and cutting torque under different processing steps are determined.The loading time of the accelerated degradation test is calculated by Miner fatigue cumulative damage theory,and the design of the motorized spindle accelerated degradation test program is completed.And test according to the set test protocol.Finally,a reliability evaluation model of motorized spindle based on no-failure data is proposed.The distribution probability estimation of the motorized spindle under each censoring time is obtained by using the distribution curve method and EBayes method.The motorized spindle is obtained by weighted least squares method.Point estimate of reliability.The method of introducing the parameters Bootstrap is repeated random self-sampling from the accumulated cumulative fault distribution curve of the motorized spindle,and the confidence interval estimation of the motorized spindle is estimated by the new sample,thereby realizing the reliability evaluation of the motorized spindle,and the traditional The confidence interval of the confidence limit analysis method is used to verify the reliability and superiority of the method.The reliability evaluation method of the motorized spindle proposed in this paper can effectively avoid the problem that the traditional method cannot be analyzed without failure data,and provides a new idea for the reliability evaluation of the motorized spindle.