3 Fundamentals of press design

Force and work requirement
d 0 d 2
h 0
V 2
V 1 ’
F
V 1 α 2
d 1
2 π
V0 d0 h0 mm
4
3
= ⋅ ⋅ [ ]
2 π
V1 d1 h1 mm
4
3
= ⋅ ⋅ [ ]
3
( ) [ ]
h1
2 2
V1
= d2d1d2 d1 mm
12
⋅ π ’
' ⋅ + + ⋅
2 π
V2 d2 h2 mm
4
3
= ⋅ ⋅ [ ]
In this calculation, it is possible to use d 2 � d 0 as an approximation; the
height of the truncated cone h 1’ and the forming stroke h are determined
by means of:
h '
1
d2 – d1
cot α h h0 – h2 mm
2
= = [ ]
The amount of deformation (strains) can be determined from the
degree of true strain � and the specific cross section change � A . The latter
can be obtained quickly from the relevant squares of the diameters
instead of using the surfaces:
ϕ= ⎛ ⎞
⎜ln
⎟
⎝ ⎠
d
2
2
2
d
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998
1
h 2
h 1 ’
h 1
Fig. 6.5.1
Schematic representation
of forward rod extrusion
471