A method for selecting and matching mechanical parts based on geometrical tolerance and dimensional tolerance is disclosed

Abstract

The invention discloses a method for selecting and matching complex mechanical products based on genetic algorithm, which comprehensively considers shape and position tolerance and dimension tolerance, through the coding method of complex dimension chain, the assembly problems of complex mechanical products are mapped into mathematical models, assembly accuracy and assembly success rate are used as the evaluation indexes of quality requirements, a comprehensive optimization model of selection and matching under the multi-quality requirements is established, by using the effective characterization form of the measured values of geometrical tolerances in the selection, the optimization model of geometrical tolerances and dimensional tolerances is established, Based on Pareto intensity and density as fitness evaluation criteria of genetic algorithm, the algorithm is improved by introducing the priority of parts and the priority of quality requirement. The method not only realizes the selection and matching of complex mechanical products, improves the success rate of assembly, ensures the assembly accuracy, ensures the dimensional tolerance assembly accuracy, but also effectively reduces the shape and position tolerances of products, and the genetic algorithm with the priority of selection and matching has a better convergence speed.

Description

technical field [0001] The invention relates to the field of selecting and assembling complex mechanical products, in particular to a method for selecting and matching mechanical parts based on shape and position tolerances and dimensional tolerances. Background technique [0002] Complex mechanical products often have the characteristics of high R&D costs, complex product composition, and complex constraint relationships between parts and components. In the assembly process, the quality of the parts to be assembled and the transmission and accumulation of deviations on the assembly dimension chain jointly affect the product quality. In order to ensure that this complex mechanical product assembled from a large number of multi-quality parts has high matching accuracy, if only the manufacturing accuracy of the parts is continuously improved, the production cost will inevitably be greatly increased. On the premise of not increasing the manufacturing accuracy, the selective as...

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Problems solved by technology

[0004] In summary, the method based on the grouping strategy depends on the size distribution of parts, and it is difficult to apply to assemblies that do not obey a specific distribution and have complex structures.

Although intelligent algorithms can achieve good results in single-objective optimization, complex mechanical products often have the characteristics of high quality requirements and complex dimensional chains in assembly, which makes it difficult for intelligent algorithms to simultaneously coordinate multiple qualities in multi-objective optimization. optimization required

At the same time, the above research on matching ignores the shape and position tolerance of the product. In fact, in addition to the influence of the change of dimensional features, that is, the size error, the change of shape and position features, that is, the shape and position error, will also affect the final quality of the entire assembly.

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