Improvement of the Forming Limit of Sheet Metals by Removal of Surface Roughening with Plastic Strain

通过塑性应变去除表面粗糙来提高金属板材的成形极限

• 批准号: 03650105
• 负责人: YAMAGUCHI Katsuhiko
• 金额: $ 1.34万
• 依托单位: Kyoto Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1992
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03650105/
• 关键词: Sheet metal forming; Thickness dependence; Forming limit; Surface Roughening; Biaxial stretching; Metal foil; 成形限界向上; 板厚不均一さ; 表面あれ除去; 極薄板; 張出成形; 単純変形経路; 変形様式

In sheet metal forming, press shops are forced to use thin sheets to reduce the weight of products. However, the press forming of thin sheets is very difficult because the formability of a sheet metal generally decreases with decreasing the thickness. Such thickness dependence of the formability of sheet metal is closely related to the surface roughening behavior with plastic deformation of the sheet.In this investigation, the surface roughening of sheet metals with plastic strain is removed at a given strain during the forming process, and its effect on the improvement of the forming limit is discussed.As a preliminary examination to estimate how the onset of a localized necking is delayed by the removal of surface roughness, a rigid-plastic finite element simulation is first made. Experiments using aluminium and killed steel sheets are also carried out, and the increase in forming limit strain is examined under a few strain paths.It is shown that the improvement of the forming limit is considerable in the stretch forming region where the major and minor strains in the plane of a sheet are positive. For balanced biaxial stretching, for example, the forming limit strain can be increased up to about 1.3 to 1.4 times as large as that for ordinary in-plane stretching. The effect of surface roughness removal becomes large as the thickness of sheet decreases.

在钣金成形中，冲压车间被迫使用薄板来减轻产品重量。然而，薄板的冲压成形是非常困难的，因为金属板的可成形性通常随着厚度的减小而降低。板料成形性的厚度依赖性与板料塑性变形时的表面粗糙化行为密切相关，在本研究中，在成形过程中，在给定的应变下，消除具有塑性应变的板料表面粗糙化，并讨论了它对提高成形极限的作用。作为估计局部颈缩的发生如何被延迟的初步检验，在去除表面粗糙度方面，首先进行了刚塑性有限元模拟。用铝板和镇静钢板进行了实验，考察了几种应变路径下成形极限应变的提高情况，结果表明，在板料平面内主应变和次应变均为正值的拉伸成形区，成形极限的提高是相当可观的。对于平衡双轴拉伸，例如，成形极限应变可以增加到普通面内拉伸的成形极限应变的约1.3至1.4倍。表面粗糙度去除效果随板厚的减小而增大。

项目成果

高倉 章雄: "表面あれ除去による極薄板の成形限界の向上" 平成5年度塑性加工春季講演会講演論文集. (1993)

Akio Takakura：“通过去除表面粗糙度提高超薄板材的成形极限”1993 年春季塑性工作会议记录（1993 年）。

Takakura, N: "Improvement of Forming Limit of Thin Sheet Metals by Removal of Surface Roughening with Plastic Strain" Proc. 1993 Japanese Spring Conf. Tecnol. Plasticity. (1993)

Takakura, N：“通过塑性应变去除表面粗糙度来改善薄板金属的成形极限”Proc。

高倉 章雄: "表面あれ除去による極薄板の成形限界の向上" 平成5年度塑性加工春季講演会講演論文集 1993-5. (1993)

Akio Takakura：“通过去除表面粗糙度提高超薄板的成形极限”1993 年春季塑料加工会议，1993-5 号论文集（1993 年）。