Research on the Flexible Adjustment Cell for Mechanical Assembly

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(1) As the essential device of the flexible adjustment, the micro-impact hummers (MIHs) made by the piezoelectric actuators were newly developed, and were installed into the 2 dimensional NC positioning table. By using this device, the experiments on the automatic micro adjustment of the positional and orientational deviation for the bolt-fastened component were done. The results of the experiments showed that the developed device could stably adjust the position and orientation of the jig-component with the initial deviation of 30 mum and 0.001 rad into the allowable deviation zone of 5 mum and 0.0002 rad.(2) For the purpose on the optimal tolerances synthesis of the mechanical assembly, a computer aided system for the 3D tolerance synthesis system was developed. The assembly was represented by solid model, and dimensional and geometrical tolerances were formulated as a set of inequalities. Differential coordinate transformation and linear programming were used to analyze the dimensional and geometrical tolerance stack-up. The cost data base descried the relation among form featured, tolerance range, machining and set-up costs. Tolerance synthesis was formulated as the combinational optimization problem under the stack-up conditions. Genetic Algorithm was applied to solve these problems. The coding method and genetic operators were discussed. The algorithm was evaluated through the tolerance synthesis for the gear box. It was confirmed that the proposed GA based tolerance synthesis method could find the optimum tolerance allocation plan for a rational period.