城轨底架多特征加工中的空走刀路径优化

Optimization of Idle Tool Path in Multi-Feature Machining of Urban Rail Chassis

为实现城轨底架加工效率的提升,建立了以刀具空走刀路径和换刀次数为优化目标的数学模型并改进NSGA-Ⅱ算法进行求解。首先,通过MSOS染色体对特征和刀具进行编码;其次,采用动态拥挤度排序方式和精英保留策略选择个体,保证子代种群的多样性和保留优秀个体;最后,为增加种群的多样性依据迭代次数改变变异操作。实例计算结果表明,与传统分组规划法取得的目标值相比较,采用改进NSGA-Ⅱ算法所获得的刀具空走刀路径和换刀次数最多分别减少34.2%和25%,验证了该算法在城轨底架多特征加工中的可行性和有效性,提高了生产效率。

In order to achieve the improvement of the machining efficiency of the city rail base frame, a mathematical model with the empty tool path and the number of tool changes as the optimization objectives is established and solved by the improved NSGA-Ⅱ algorithm.Firstly, features and tools are encoded by MSOS chromosomes.Secondly, dynamic crowding ranking and elite retention strategy were used to select individuals to ensure the diversity of offspring population and retain excellent individuals.Finally, the mutation operation was changed according to the number of iterations to increase the diversity of the population.The calculation results of an example show that compared with the target value obtained by the traditional group programming method, the empty tool path and tool change times obtained by the improved NSGA-Ⅱ algorithm are reduced by 34.2% and 25% respectively, which verifies the feasibility and effectiveness of the algorithm in multi-feature machining of urban rail chassis, and improves the production efficiency of enterprises.