中文摘要：

管筒形零件的机械扩径成形过程是一个与管坯规格、管坯形状、材料性能、摩擦条件、变形程度、模具直径及其边缘圆角半径等诸多因素相关的塑性变形过程，其最终制品的尺寸和形状精度取决于这些参数的综合影响。在生产实际中，如何根据用户对制品尺寸与形状的精度要求来确定管坯规格、变形程度、模具尺寸等主要工艺参数，是机械扩径工艺设计的一个重要内容。它可以被抽象为一个在满足制品尺寸和形状精度要求条件下，寻求管坯规格等上述主要工艺参数最优组合的多目标优化问题。文章基于MSC．Marc非线性有限元分析软件和遗传优化算法，采用Python语言设计了基于加权组合法的遗传算法程序，实现了在多目标条件下对管筒形零件机械扩径成形工艺参数的优化。

英文摘要：

The mechanical expanding of cylinders is a plastic deformation process which is involved with errors in outside dimension and geometrical form of the cross-section of cylindrical billet, material properties, friction condition, degree of deformation, diameters of dies, and so on. The precision of dimension and geometrical form of the final products depends on effects of all these parameters. It is an important matter in design of mechanical expanding technical process that how to confirm dimension of cylindrical billet, degree of deformation, diameter and radius of comer of dies, and otherwise which are key technological parameters basing on precision of dimension and geometrical form of products which is desired by users. It can be abstracted as a multi-objective optimization problem that searches optimum combination of the above four key technological parameters under the condition of meeting precision of final products. This paper realized optimization of mechanical expanding technological parameters of cylinder by multi-objective optimization based on MSC. Marc, nonlinear software of finite element method, and genetic algorithm of optimization, and designing a genetic algorithm program in Python with weighted array algorithm.