| Project/Area Number |
03650105
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
機械工作
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| Research Institution | Kyoto Institute of Technology |
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Principal Investigator |
YAMAGUCHI Katsuhiko Kyoto Inst. Tech. Professor Dept. Mech. & System Eng., 工芸学部, 教授 (90027805)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAKURA Norio ibid. Instructor, 工芸学部, 助手 (40163183)
IMATANI Shoji ibid. Associate Professor, 工芸学部, 助教授 (70191898)
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| Project Period (FY) |
1991 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1992: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1991: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | 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 |
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| Research Abstract |
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.
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