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F=
A x Tß
F = Cutting force
S = Material thickness
L = Total cutting length
A = L x S = Shear area
Tß = Shear strength
Note : Shear strength = 80% of tensile strength
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P=
( L x S x Tß ) / 10
P = Stripping force
S
= Material thickness
L = Total cutting length
A = L x S = Shear area
Tß = Shear strength
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L
= a + ( R + q x s/2 )( Pi x ° / 180)
L = Flat blank length
a, b = Length of legs
R = Bend radius
q = Correction factor ( refer to table below )
° = Bend angle
Pi = 3.1416
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Correction
factor q
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| Ratio
R : s |
5.0 |
3.0 |
2.0 |
1.2 |
0.8 |
0.5 |
| Correction
factor |
1.0 |
0.9 |
0.8 |
0.7 |
0.6 |
0.5 |
R = Bend radius
S
= Material thickness
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E
= ( D + s ) 0.707
C = ( D + s ) 1.414
E = Center distance
C = Center distance between two apart radii
s = Material thickness
D = Inside diameter of final formed part
R = D/2 ( approximate )
Note : if R = D/2, radii will be tangent, if R /= D/2, radii
will require blending.
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Thickness
S
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1st Draw
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2nd Draw
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Sizing
Draw
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< 0.4
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1.08 S
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1.09-1.10
S
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1.04-1.05
S
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0.4 - 1.27
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1.08 - 1.10
S
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1.10 - 1.13
S
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1.05 - 1.06
S
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1.27 - 3.18
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1.10 - 1.13
S
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1.13 - 1.15
S
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1.06 - 1.08
S
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> 3.175
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1.13 - 1.15
S
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1.15 - 1.20
S
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1.08 - 1.10
S
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S = Material thickness
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Draw
reduction
( number of draw )
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H
/ D
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No.
of draw
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< 0.75
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1
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0.7 - 1.5
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2
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1.5 - 3.0
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3
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3.0 - 4.7
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4
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H
= Draw piece height
D = Mean diameter of draw piece
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%
= 1 -( MD / D )
%
= percentage of reduction
MD = Mean diameter of draw piece
D = Flat blank diameter
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A
= 0.7854 (( DXD )-(dXd))
D
= Flat blank diameter
d = Hole diameter
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A
= 3.1416 ( D x H )
D
= Mean diameter
H = Shell height
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A=
4.935 RD + 6.283 (R x R)
D = Hole diameter
R = Radius ( 1/2 thickness )
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A=
4.935 RD - 6.283 (R x R)
D = Outer diameter
R = Radius ( 1/2 thickness )
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A=
6.283 ( R x R )
R = Radius ( 1/2 thickness )
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A
= 6.283 RH
R
= Radius ( 1/2 thickness )
H = Shell height
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A
= 9.87 RD
D = center to center diameter
R = Radius ( 1/2 thickness )
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