3 Fundamentals of press design

280 Sheet metal forming and blanking
The distances between the centers of gravity in the respective coordinate system
in mm are:
a = 0 b = b = 0 a = 0
b = b = 20
a
a
a
b
b
a
a = a = 105
a
1 2
4
3
9
10 12
11
= 25
= 38. 33**
= 65
= 145
a
a = a = 20
b = b = 45
b
b
5
6
7 8
9 11
10
12
= 40
= 90
= 0
a) Calculation of the coordinates of the center of force on the basis of the
perimeters (Fig. 4.5.11b):
b) Center of force calculated using the line centers of gravity (Fig. 4.5.11 c):
b
b
5 6
7
8
= 50. 9*
= 70
r
*C enter of gravity of the semi– circular arc:yS
=
(d rawn from the straight line)
⋅ 2 60
= = 19. 10
π π
P osition in the current coordinate system: b = 70– 19. 10 = 50. 9
60⋅ 0+ 94. 25⋅19. 10
** y S =
= 11. 67 (d rawn from the straight line)
60+ 94. 25
Positioni nthe current coordinate system: b = 50– 11. 67= 38. 33
x
x
y
y
x
x
1
2
3
4
S
S
S
S
S
S
= 40
= 20
= 105
U ⋅ a + U ⋅ a + U ⋅ a + U ⋅a
=
U + U + U + U
1 1 2 2 3 3 4 4
1 2 3 4
62. 83⋅ 0+ 62. 83⋅ 40+ 154. 25⋅ 20+ 340⋅105 =
= 66. 6
62. 83+ 62. 83+ 154. 25+ 340
U ⋅ b + U ⋅ b + U ⋅ b + U ⋅b
=
U + U + U + U
1 1 2 2 3 3 4 4
1 2 3 4
62. 83⋅ 0+ 62. 83⋅ 0+ 154. 25⋅ 38. 33+ 340⋅25 =
= 23, 25
619. 9
R
l ⋅ a + l ⋅ a + l ⋅ a + l ⋅ a + l ⋅ a + l ⋅ a + l ⋅ a + l ⋅a
=
l + l + l + l + l + l + l + l
5 5 6 6 7 7 8 8 9 9 10 10 11 11 12 12
5 6 7 8 9 10 11 12
7
3
⇒ Center of gravity S ( 66. 6; 23. 25)
inthe coordinate system b.
62. 83⋅ 0+ 62. 83⋅ 40+ 94. 25⋅ 20+ 60⋅ 20+ 90⋅ 65+ 80⋅ 105+ 90⋅ 145+ 80⋅105 =
62.83
83+ 62. 83+ 94. 25+ 60+ 90+ 80+ 90+ 80
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998