1. Sheet Metal Bending

2. Historical Note;
Sheet metal stamping was developed as a mass production technology for the production of bicycles around the 1890’s. This technology played an important role in making the system of interchangeable parts economical (perhaps for the first time).

3. Stress Strain diagram – materials selection

4. Basic Sheet Forming Processes (from http://www. menet. umn
Shearing
Drawing
Bending

5. Shear and corner press

6. Shearing Operation Force Requirement
Die
Sheet
Punch T D
Part or slug
F = 0.7 T L (UTS)
T = Sheet Thickness
L = Total length Sheared
UTS = Ultimate Tensile Strength of material

7. Shearing of sheet metal between two cutting edges

8. Schematic of a Blanked Edge

12. Bending Force Requirement
Punch
T = Sheet Thickness
W = Total Width Sheared
(into the page)
L =Span length
UTS = Ultimate Tensile Strength of material
Workpiece T
Die L
Engineering Strain during Bending: e = 1/((2R/T) + 1)
R = Bend radius
Minimum Bend radius: R = T ((50/r) – 1)
r = tensile area reduction
in percent

13. Bending of sheet metal; both compression and tensile elongation

15. Springback
Over-bend
Bottom
Stretch

16. Pure Bending
tension
compression
Bending & Stretching

17. Springback