Page 215 - Mechanical Engineer's Data Handbook

MANUFACTURING TECHNOLOGY 203

Drawing process
Blank diameter D = Jm
Required force F = ndta,
where: uu = ultimate tensile stress.

f
L

F-Cl Distance x .... - P
.....
D
Shearing process

Shearing force F=- (3) 5.9.7 Sheet metal work
Allowance for right angle bend

Lengths a and b are reduced by an ‘allowance’ c, and
where: h=the ‘shear’.
c = r + t -a (r +;)
IF
When r=2t (as is often the case), c= 1.037t.
Allowance for bend with outside angle 0

2” :( :)
c=(r+t)tan--- r+- , (6 in degrees)

(: )
When r=2t, c= 3tan--0.02188 t.

Bending process

Bending force F, = r,Lt
Planishing force F, = a,Lb
where: a,=yield stress.
:)
I(
Initial length of strip Li = h - t - 2r + b + - r + -