Dynamic Servo Turret Reliability And Sensitivity Analysis

Power servo turret is a core functional unit of numerically controlled machine tool, its accuracy, stiffness and reliability indicators determine the performance of the whole machine tool to a large extent, therefore, researches on accuracy, stiffness and reliability of the power servo turret are of great significance.In this paper, we study indexing accuracy reliability, natural frequency reliability and dynamic reliability of the power servo turret. Specific content as follows:Firstly, we use two methods to establish a finite element model of the turret; the first modeling method is to combine Hypermesh with Ansys and the second one is directly modeling in Ansys.After evaluating these two methods, we find the method which directly modeling in Ansys more practicable.Taking into account that machining error and assembly error not only affect the contact state of a chainring, but also affect the locking state of the chainring, and thereby affecting the performance and reliability of the chainring, so in order to obtain machining error, assembly error and other parameters distribution, we review relevant information and do some calculation. We establish the parameterized finite element model which contains machining error and assembly error of the chainring directly in Ansys, and then it generates APDL files.Secondly, we adopt the Latin Hypercube sampling method of Isight software to generate multiple sample documents based on the APDL files and the corresponding parameters distribution.In order to reduce computing time, we use several computers to calculate simultaneously, and submit the sample documents to the computing cluster to calculate and then extract results. We establish a mathematical model of the deterministic relationship of input parameters and output results by using BP neural network, and then represent a state function based on the mathematical model.Thirdly, When the state function is relatively explicit, you can use many reliability analysis methods to solve problems,here we analyze reliability sensitivity of the state function by means of the reliability perturbation method combined whit the corresponding reliability theory; obtain the corresponding reliability of the chainring and the influences on the reliability of the various parameters.Fourthly, According to results of reliability analysis, we can see the reliability of the positioning accuracy, frequency reliability and dynamic reliability of power servo turret are high, we can obtain the impact on reliability of the various parameters through the sensitivity analysis,which can provide a certain guiding significance to the chainring design.At the same time, we prospect the problems need to be solved in the reliability sensitivity algorithm of the power servo turret.