EXTRUSION - Suranaree University of...
Transcript of EXTRUSION - Suranaree University of...
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EXTRUSION
Extrusion
EXTRUSION
2 Extrusion
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EXTRUSION
3 Extrusion
EXTRUSION PROFILE
4 Extrusion
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CLASSIFICATION
• FORWARD • BACKWARD • LATERAL
Extrusion
FORWARD EXTRUSION
6 Extrusion
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BACKWARD EXTRUSION
Extrusion - 7 Extrusion
Direct and Indirect Extrusion
8 Extrusion
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DEFECTS
9 Extrusion
PIPE
CHEVRON
IMPACT EXTRUSION
10 Extrusion
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HYDROSTATIC EXTRUSION
11 Extrusion
EXTRUSION DIE
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Analysis of the Extrusion Process
Extrusion ratio R = A0/Af
Velocity of extruded product = ram velocity x R
Pe = Pd + Pfb + Pff
Pd = die force Pfb = friction between container and billet Pff = friction between Billet and follower block
Extrusion
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Pff = 0 , L
DPf i
2
D = 4
D
L4 = P i
f
Sach Bd R
B
B = P
11
0
B = cot = Friction coefficient = Semi-die angle
From slip-line theory of plane strain
Rlnba = P od
a = 1.8 and b = 1.5 for axi-symmetry extrusion
Extrusion
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Kudo - Upperbound theory ; for square die 2 = 180o
Rln.. = P 0d 551061
Avitzur - more genelized expression ; for lubricated extrusion by semidie angle
cotr
r
r
Lm
r
rlncotmfcot
sin3
2=P f
f
0d
00
002
122
m = interfacial friction condition f = complex function for semidie angle ; f =1 for small die angle
L = length of land on exit from die r0 = radius of billet
rf = radius of extruded rod
Extrusion
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Depierre - Upper-bound (good agreement on hydrostatic extrusion)
RlncotmkRlnba = Pd 0
a b
30 0.419 1.006 45 0.659 1.016 60 0.945 1.034
Strain rate
bD
6vlnR = =
tt
For flat die
For semi die angle
33
2 tanln6
eb
bt DD
RvD
Extrusion
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Example
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Ex. An aluminum alloy AlMg5 is hot extruded at 450oC at 50mm/s from 150 mm diameter to 50 mm diameter. If the billet is 380 mm long, determine the force required for the operation. The extrusion is done through square die without lubricant.
Extrusion