Book contents
- Frontmatter
- Contents
- Preface to Third Edition
- 1 Stress and Strain
- 2 Plasticity
- 3 Strain Hardening
- 4 Instability
- 5 Temperature and Strain-Rate Dependence
- 6 Work Balance
- 7 Slab Analysis and Friction
- 8 Upper-Bound Analysis
- 9 Slip-Line Field Analysis
- 10 Deformation-Zone Geometry
- 11 Formability
- 12 Bending
- 13 Plastic Anisotropy
- 14 Cupping, Redrawing, and Ironing
- 15 Forming Limit Diagrams
- 16 Stamping
- 17 Other Sheet-Forming Operations
- 18 Formability Tests
- 19 Sheet Metal Properties
- Index
- References
18 - Formability Tests
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface to Third Edition
- 1 Stress and Strain
- 2 Plasticity
- 3 Strain Hardening
- 4 Instability
- 5 Temperature and Strain-Rate Dependence
- 6 Work Balance
- 7 Slab Analysis and Friction
- 8 Upper-Bound Analysis
- 9 Slip-Line Field Analysis
- 10 Deformation-Zone Geometry
- 11 Formability
- 12 Bending
- 13 Plastic Anisotropy
- 14 Cupping, Redrawing, and Ironing
- 15 Forming Limit Diagrams
- 16 Stamping
- 17 Other Sheet-Forming Operations
- 18 Formability Tests
- 19 Sheet Metal Properties
- Index
- References
Summary
There are many tests of formability for sheet materials. A given test may correlate well with behavior in one type of forming process and poorly with behavior in another. This is because the relative amounts of drawing and stretching vary from test to test and process to process.
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 18.1 shows the setup.
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 18.2 shows the setup. A failed Fukui cup is shown in Figure 18.3.
Figure 18.4 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 drawing in of the flange, and inconsistent lubrication.” He proposed the limiting dome height test (LDH) which uses the same tooling (4 in. diameter punch) as used to determine forming limit diagrams.
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- Information
- Metal FormingMechanics and Metallurgy, pp. 279 - 288Publisher: Cambridge University PressPrint publication year: 2007