【作者】 周朝辉；

【导师】 何大钧；

【作者基本信息】 重庆大学 ， 材料加工工程， 2002， 硕士

【摘要】 本文采用有限元数值模拟方法，结合金属高温塑性成形的特点，详细论述了刚粘塑性有限元法的基本理论及处理方法，推导出了基于罚函数法和过应力模型的热力耦合刚粘塑性有限元列式，并建立了求解初始速度场的近似泛函，导出了求解方程。 根据上述有限元理论和处理技术，结合工程实际应用，针对厚壁筒形件的热拉深成形，建立了热力耦合刚粘塑性有限元模型，并进行了模拟计算。分析了金属应力、应变、成形载荷、温度场及颈缩缺陷与成形工艺、预制坯尺寸、模具尺寸、冷却条件的关系，提出了消除颈缩缺陷的解决方案，给出了优化的成形工艺并得出了模拟结果。 本文在厚壁圆筒件的热拉深工艺及有限元模拟方面作了一些有效的探索，可得出如下结论： (1)一次拉深接近极限拉深系数，筒壁的等效应力超过了抗拉强度，将产生颈缩缺陷。 (2)采用温差拉深可有效提高筒壁承载能力，减少颈缩量。 (3)利用热交换区域设置边界条件，成功的建立了水冷模型，模拟结果表明，模型的建立是正确的。对类似的有限元建模有很大的指导意义。 (4)采用二次拉深的工艺方案，可增大拉深系数，减少坯料变形程度，降低其所受内应力，可望消除颈缩缺陷。 (5)凹模圆角半径或相对凹模圆角半径对筒壁壁厚变化影响很大，必须引起重视。更多还原

【Abstract】 This article adopts the finite element numerical simulation method,and combining the shaping characteristic of metal high temperature plasticity,and had detailedly discussed just the basic theory of viscoplasticity finite element method and deals with the method,the derivation has been gone out to based on that the type is arranged in the finite element of viscoplasticity having punished the function law and the heating power coupling crossing the stress model just,and built at the beginning of finding the solution the approximate general letter of velocity field,and led out to find the solution the equation.According to mentioned above finite element theory and the processing technology,combining the engineering application,is directed against the thick wall tin shape forging warms to draw deeply,built the heating power coupling finite element model of viscoplasticity just,the advance side by side line analog computation. Analysed metal stress and meets an emergency and load,temperature field and the neck down defect and forming technique and prefabricates base ready to be machined into a finished product size,mould size and become cool the relation of condition,and put forward eliminating the neck to contract the settlement scheme of defect,and gave out forming technique that optimizes and his to imitate at last.Doing some active explores of hot drawing technics and FE simulation for thick cylinder in this article,and can reach the following conclusion:(1)Once drawing to be close to the limit drawing coefficient,and the effective stress of section of wall surpassed tensile strength,and will give rise to the neck down.(2)Adopt the difference in temperature to draw and effectively to raise a wall bearing capacity deeply,and reduces the neck down.(3)The utilization heat exchange boundary conditions is set up successfully,and built the water-cooling model,and imitates the result to indicate that the establishment of model is correct. There is the very big guidance meaning to the similar finite element builds the pattern.(4)Adopting two times drawing the technology scheme,and can enlarge drawing coefficient,reduce the base becoming deformed the level,and reduces the internal stress which received,hopefully eliminating the neck down.(5)Concave die circle horn radius or relatively concave die circle horn radius is verybig to a section of thick change of the wall influence relatively must cause attaching importance to.更多还原