Book contents
- Frontmatter
- Contents
- Preface to the Fourth Edition
- 1 Stress and Strain
- 2 Plasticity
- 3 Strain Hardening
- 4 Plastic Instability
- 5 Temperature and Strain-Rate Dependence
- 6 Work Balance
- 7 Slab Analysis
- 8 Friction and Lubrication
- 9 Upper-Bound Analysis
- 10 Slip-Line Field Analysis
- 11 Deformation-Zone Geometry
- 12 Formability
- 13 Bending
- 14 Plastic Anisotropy
- 15 Cupping, Redrawing, and Ironing
- 16 Forming Limit Diagrams
- 17 Stamping
- 18 Hydroforming
- 19 Other Sheet Forming Operations
- 20 Formability Tests
- 21 Sheet Metal Properties
- Index
- References
20 - Formability Tests
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface to the Fourth Edition
- 1 Stress and Strain
- 2 Plasticity
- 3 Strain Hardening
- 4 Plastic Instability
- 5 Temperature and Strain-Rate Dependence
- 6 Work Balance
- 7 Slab Analysis
- 8 Friction and Lubrication
- 9 Upper-Bound Analysis
- 10 Slip-Line Field Analysis
- 11 Deformation-Zone Geometry
- 12 Formability
- 13 Bending
- 14 Plastic Anisotropy
- 15 Cupping, Redrawing, and Ironing
- 16 Forming Limit Diagrams
- 17 Stamping
- 18 Hydroforming
- 19 Other Sheet Forming Operations
- 20 Formability Tests
- 21 Sheet Metal Properties
- Index
- References
Summary
CUPPING TESTS
The Swift cup test is the determination of the limiting drawing ratio for flat-bottom cups. In the Erichsen and Olsen tests, cups are formed by stretching over a hemispherical tool. The flanges are very large so little drawing occurs. The results depend on stretchability rather than drawability. The Olsen test is used in America and the Erichsen in Europe. Figure 20.1 shows the set up.
The Fukui conical cup test involves both stretching and drawing over a ball. The opening is much larger than the ball so a conical cup is developed. The flanges are allowed to draw in. Figure 20.2 shows the set up. A failed Fukui cup is shown in Figure 20.3.
Figure 20.4 shows comparison of the relative amounts of stretch and draw in these tests.
LDH TEST
The cupping tests discussed above are losing favor because of irreproducibility. Hecker attributed this to “insufficient size of the penetrator, inability to prevent inadvertent draw in of the flange and inconsistent lubrication.” He proposed the limiting dome height (LDH) test which uses the same tooling (4 inch diameter punch) as used to determine forming limit diagrams. The specimen width is adjusted to achieve plane-strain and the flange is clamped to prevent draw-in. The limiting dome height is greatest depth of cup formed with the flanges clamped. The LDH test results correlate better with the total elongation than with the uniform elongation as shown in Figures 20.5 and 20.6.
- Type
- Chapter
- Information
- Metal FormingMechanics and Metallurgy, pp. 294 - 303Publisher: Cambridge University PressPrint publication year: 2011
References
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