金属板材单点渐进成形数值模拟及优化分析

发布时间：2018-03-27 16:37

本文选题：渐进成形　切入点：优化设计　出处：《浙江工业大学》2015年硕士论文

【摘要】：金属板材在数控渐进成形过程中,经历了复杂的应力、应变变化过程,零件在加工过程中会存在各种缺陷,为提高成形件的质量和精度,需要对渐进成形机理进行深入的研究,并在此基础上对渐进成形进行优化分析,通过合理的选择成形过程中的工艺参数,设计合理的工具头路径,避免成形过程中出现过度减薄和板材破裂的情况。基于塑性力学理论对渐进成形的应力、应变和板厚分布进行理论计算,在此基础上模拟了单点渐进成形有限元仿真的过程,解决了数值模拟中的关键问题:包括单元选择、材料模型选择、接触处理和路径加载等问题,并将模拟结果与理论计算对比,证明有限元模型的有效性。在此有限元模型的基础上对渐进成形进行优化设计,主要包括轨迹优化和参数优化两个部分,对比得到螺旋线进给方式相较于直线进给方式能提高板材成形性能;采用多道次成形设计能解决成形件板厚分布不均匀的情况,并能加工出成形角度超过成形极限的制件。参数优化主要确定了工具头直径、板材厚度、成形角度和单层进给量对渐进成形性能的影响,进一步通过正交试验确定影响板材渐进成形减薄率的主要因素是成形角度、进给量与工具头直径,次要因素是板材厚度。利用响应面法,建立了多参数回归方程,量化了各参数对板材减薄率的影响,提出了一种综合考虑多参数的预测板材减薄率的方法;在此基础上建立了减薄率响应面优化模型,采用二次规划优化算法(SQP)迭代求解目标函数的最优解,并根据优化分析结果加工出厚度分布较为均匀的汽车翼子板。
[Abstract]:In the process of numerical control progressive forming, metal sheet has experienced complex stress and strain changes, and parts will have various defects in the process of machining. In order to improve the quality and accuracy of forming parts, it is necessary to deeply study the mechanism of progressive forming. On the basis of this, the paper optimizes and analyzes the gradual forming process, and designs a reasonable tool head path by selecting the process parameters in the forming process. Based on the plastic mechanics theory, the stress, strain and plate thickness distribution of progressive forming are calculated theoretically, and the finite element simulation process of single point incremental forming is simulated based on the theory of plastic mechanics. The key problems in numerical simulation are solved, including element selection, material model selection, contact treatment and path loading, and the simulation results are compared with theoretical calculation. It is proved that the finite element model is effective. On the basis of the finite element model, the design of incremental forming is optimized, which includes two parts: trajectory optimization and parameter optimization. The results show that the helical feeding method can improve the sheet metal forming performance compared with the linear feed method, and the multi-pass forming design can solve the problem of uneven thickness distribution of the forming parts. The influence of tool head diameter, sheet thickness, forming angle and monolayer feed on the incremental forming performance is determined. Through orthogonal test, it is determined that the main factors affecting the thinning rate of sheet metal progressive forming are forming angle, feed rate and tool head diameter, and the secondary factor is sheet thickness. By using the response surface method, the multi-parameter regression equation is established. This paper quantifies the influence of each parameter on the thinning rate of the plate, and puts forward a method of predicting the thinning rate of the plate considering multiple parameters synthetically, and establishes the response surface optimization model of the thinning rate on the basis of the method. The quadratic programming optimization algorithm (SQP) is used to iteratively solve the optimal solution of the objective function. According to the results of the optimization analysis, the uniform thickness distribution of the automobile airfoil is obtained.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG306

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