Deformation Behavior and Ductility in Free Forging with Convex Die.

凸模自由锻造的变形行为和延展性。

• 批准号: 04650624
• 负责人: MORITOKI Hitoshi
• 金额: $ 1.28万
• 依托单位: Akita University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1992
• 资助国家: 日本
• 起止时间: 1992 至 1993
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04650624/
• 关键词: Forging; Limit of Ductility; Plastic Instability; Forming Limit; Localized Necking

Improvment for spring characteristic and strength of sheet metals has been brouhgt by giving them plastic deformation through free forging with convex shape dies. Here, the deformation behavior and ductility in sheet metal forging with cylindrical dies are investigated. Slab method under plane strain is used in order to evaluate deformation behavior. Forging region of a sheet increases with forging process at the early stage of forging, but after the middle stage its increase changes to decrease. At the center of the forging sheet the sterss along longitudinal direction is tensile, in many cases, thouhgh depending upon tool radius and friction coefficient, and it becomes maximum near middle stage, after which it decreases and shifts to compressive. When the maximum tensile stress is too high, ductile fracture may be possible to arise.We proposed general criteria for ductility based on plastic instability, and tried to predict the formability of various metal formings. They correspond t … More o modified diffuse necking by Swift and to modified localized necking by Storen & Rice. The materials used are strengthened aluminium, phospher bronze and stainless steel. The cracking of the aluminium and steel occurs at the interior of materials under plane strain, but that of the bronze does at sheet edge under plane stress. Ductiltiy limit obtained by experiment is compared with analytical estimation on the aluminium, because the bronze shows different view of fracture, and the fracture of the steel and a part of the bronze occurs after very large deformation where very high hydrostatic pressure arises, which rejects all of application of any criteria proposed on phenomenological basis and plastic instability.The ductility on the aluminum shows, on the whole, good agreement between experiment and analysis, though experimental values are a little higher than analytical ones. The cracking appearing after very large deformation should be inverstigated considering all possible items producing effects on the change of stress state, for example, the flatting of dies under high pressure. Less

通过凸出的量表来改造板的弹簧特征，使它们的塑料变形通过凸的行为和用圆柱状的板材锻造。在许多卡斯中，沿纵向的螺母在纵向上，在工具半径和摩擦系数上，它变成了中间阶段，然后在最大拉伸应力过高时会减少。出现。我们基于塑料不稳定性的一般固定性标准，并试图使它们形成各种金属形成。将铝和钢的破裂与铝的分析估计值进行了比较，因为铜显示了不同的断裂视图，钢的断裂和青铜高位拒绝在现象学基础上提出的所有标准的应用。铝上的灰尘总体上显示出良好的一致性分析，尽管实验值是在较轻的情况下进行的。无验证的cossider Atems产品对压力状态的变化，较高的模具的扁平化