3 Fundamentals of press design

Force and work requirement
For die design, the pressure on the container wall p i [N/mm 2 ] is determined:
1
p = p + k + k
2
( ) ⎡
Example:
The sample calculation provided here is based on the workpiece material 1.0303
(QST 32-3). The starting values are specified on the left, the characteristic values
subsequent to the pressing operation on the right.
d 0 = 75 mm d 1 = 45 mm a = 45°
h 0 = 110 mm h 2 = 65 mm
d 2 = 75.3 mm
=> h = 45 mm
The resulting deformation or ideal effective strain is � = 1.03, which corresponds
to a relative cross section change of � A � 64 %, and the correction coefficients
are k h � 1.09 and k 2� � 1.15:
If the amount of deformation is 1.03, the resulting value for k f1 is approx.
740 N/mm 2 , (k f0 250 N/mm 2 ), meaning that the specific forming work is
approx. 471 Nmm/mm 3 . With an efficiency of
the specific die loads, force and work result in:
N
⎣⎢ mm
i St f0 f1
2
ϕ = ε
⎛ ⎞
⎜ ⎟ = =
⎝ ⎠
( ) 2
2 2
75. 3
75. 3 – 45
ln 103 .
⋅ 100 % = 64 %
2
2
45
75. 3
= ⋅ α
⎛ ⎞
02 . + . ≈ . = ⋅ ⋅ + . ≈ .
⎝ ⎠ 110
1
kh08 109 k22
45 0 7 1 15
75
200
ηF = 0. 703125⋅ 64 / 100 = 0. 67
p 510 / 0. 67 1. 09 1. 15 957 N/ mm
St
2
= ⋅ ⋅ ≈ [ ]
2 – 3
FU957 75. 3 π / 4 10 4, 261 kN
W = 4, 261⋅ 0. 045 ≈ 192 [ kJ r esp.
kNm]
2
pi= 1/
2 ( 957 + 250 + 740) ≈ 974 [ Nmm / ]
= ⋅ ⋅ ⋅ ≈ [ ]
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998
⎤
⎦⎥
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