Modeling And Optimization Of Tolerance Design For The Key Parts Of Micro-Motor

Manufacturing cost and performance of product are affected by tolerance designsignificantly. The consistency of micro-motor quality is often poor, as well as itsquality with too much fluctuation when micro-motors are mass produced. Therefore,the paper takes micro-motor for research object. Firstly, the major factors whichaffect the quality of the micro-motor are analyzed. Secondly, weight of each factor iscalculated. Then, tolerance cost model for key parts of micro-motor is established,and the relationship model between micro-motor key parts dimension deviation andthe product performance deviation is proposed at the same time. The main study workis presented as follows:(1) The concurrent researches for tolerance design，which concluded toleranceanalysis and tolerance synthesis are introduced in details. In addition micro-motorresearch state, permanent magnet DC micro-motor work principle, main componentsare also introduced in detail.The main contents and general structure of thisdissertation are given.(2) Main factors which influencing the quality of micro-motor are analyzed.Related significant coefficient, relevant index and absolute influence coefficient thatamong the network layer matrix are calculated by using the neural network. What’smore, the weights of micro-motor key parts dimensional deviation which impact onthe performance deviation are obtained. According to the importance of performancedeviation of the micro-motor affect the quality of micro-motor, the comparativematrix of binary compared sort is established. Furthermore, the weights ofperformance deviation of the micro-motor which affect the quality of micro-motor areobtained.(3) The modeling method for manufacturing cost of micro-motor key componentsis studied. Then, the manufacturing cost models for the iron core height, the axisdiameter, cabinet inside diameter and the diameter of the commutator are built.Product quality loss functions, under nominal the best, smaller the better and largerthe better circumstances, are analyzed. Based on weights, quality loss model of multi-quality characteristics which oriented micro-motor product is built.(4) Modeling method about the relationship between the key parts ofmicro-motor dimension deviation and products performance deviation is studied. This relationship is so complex that it is difficult to use the conventional method to solve.Therefore, the relation between the key parts of micro-motor dimension deviation andperformance deviation is expanded by using Taylor formula. And then the partialderivative of the Taylor expansions is determined by regression analysis. Eventually,relationship model between the key parts of micro-motor dimension deviation andperformance deviation is gained.(5) Taking tolerance cost of key parts for target function and the performancerequirements of micro-motor and economic precision processing for constraintconditions, the key parts tolerance is optimized. The optimization results show thatthe modeling method proposed in this paper is valid. It provides a new way totolerance optimization design for product.