Precision And Reliability Analysis Of Internal Parallel Move Indexing Cam Mechanism

The precision level decides the performance of mechanism, and reliability decides the normal operation of mechanism, so it is necessary to analyze the precision, synthesize the precision, analyze the reliability and optimize of the mechanism for design a mechanism.Internal parallel move indexing cam mechanism is a new intermittent mechanism, the design error、machining error or assembly error will influence the output position and output angular of mechanism, lead to not ideal output movement, and influence the output precision of the mechanism. So in this paper the output error computation model of the mechanism based on the principle of the projection of original error in the direction of applied force has been built, the precision synthesis based on Monte Carlo Method and the reliability analysis based on Genetic Algorithm are done, and finally an optimization model is built to optimize the mechanism.Firstly, the output angular error of Internal parallel move indexing cam mechanism which influenced by eccentric bushing eccentricity error, the error of roller distribution circle radius and roller radius error is analyzed. Through computed mechanism’s roller mesh join forces, mechanism’s total action line and the line of motion are deduced, and output angular error computation model of multi-tooth meshing is built.Secondly, in order to get more optimal design scheme, advance calculation and distribution of parts precision range before the processing and assembling of the mechanism is needed, so this paper uses Monte Carlo Method to synthesize the precision of the mechanism, conducts a reasonable tolerance distribution based on accuracy requirement and processing cost.Thirdly, a reliability index computation model whose design variable is the original error of this mechanism is built based on the definition of reliability index β from Hasofer and Lind, and the reliability is computed based on Genetic Algorithm.Finally, a reliability optimization model is built to optimize the mechanism, whose objective function is minimum volume of cam and constraint condition is the rest indicators.