基于遗传算法的AZ31镁合金手机壳的热冲压工艺优化

Optimization of hot stamping process of AZ31 magnesium alloy cell phone case based on genetic algorithm

为探究AZ31镁合金手机壳制件的热冲压变形行为,以及工艺参数与质量评价指标间的关系、改善成形质量,借助DYNAFORM有限元软件建立手机壳模型,分析其热冲压成形规律。在250℃条件下,对制件进行热冲压仿真分析,采用正交分析和灰色系统理论(GS理论)对压边力、冲压速度、摩擦系数及阻力系数与最大增厚率、最大减薄率的关系进行深入分析。采用遗传算法(GA)优化冲压速度、阻力系数两个关键影响参数,利用反向传播(BP)神经网络进行寻优检验。结果表明,制件的冲压变形是不均匀的,圆角边缘处最容易出现起皱现象,凸模圆角处最容易发生破裂,底部和大部分侧壁几乎无塑性变形;阻力系数和冲压速度对最大减薄率的影响较大,而压边力和摩擦系数的影响较小。在追求最大减薄率最小化的问题上,GA优化策略在预测精度和优化效能上表现优异,有限元仿真证实了其准确性和有效性。研究为AZ31镁合金的热冲压分析提供了实用的优化策略,具有实际应用价值。

In order to investigate the hot stamping deformation behavior of AZ31 magnesium alloy cell phone case parts,the relationship between each process parameter and the quality evaluation indexes,and improve the forming quality,DYNAFORM finite element software,a model of the cell phone case was established to analyze its hot stamping forming law.Under the condition of 250℃,the simulation analysis of hot stamping is carried out on the parts,and the relationship between the blank holder force,stamping speed,friction coefficient and resistance coefficient and the maximum thickening rate and the maximum thinning rate are deeply analyzed by using the orthogonal analysis and the gray system theory(GS theory).Genetic algorithm(GA)was used to optimize the two key influence parameters of stamping speed and resistance coefficient,the optimality search test is carried out by using back propagation(BP)neural network.The results show that the stamping deformation of the part is non-uniform,with wrinkling most likely to occur at the edges of the rounded corners,rupture most likely to occur at the rounded corners of the convex die,and virtually no plastic deformation at the bottom and most of the sidewalls.The drag coefficient and the stamping speed have a greater influence on the maximum thinning rate,whereas the blank holder force and the friction coefficient have a lesser influence.In the pursuit of minimizing the maximum thinning rate,the GA optimization strategy shows excellent prediction accuracy and optimization efficiency,and finite element simulation confirms its accuracy and effectiveness.This study provides a practical optimization strategy for the hot stamping analysis of AZ31 magnesium alloy,which has practical application value.