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EXTRUSION

Extrusion

EXTRUSION

2 Extrusion

EXTRUSION

3 Extrusion

EXTRUSION PROFILE

4 Extrusion

5

CLASSIFICATION

• FORWARD • BACKWARD • LATERAL

Extrusion

FORWARD EXTRUSION

6 Extrusion

BACKWARD EXTRUSION

Extrusion - 7 Extrusion

Direct and Indirect Extrusion

8 Extrusion

DEFECTS

9 Extrusion

PIPE

CHEVRON

IMPACT EXTRUSION

10 Extrusion

HYDROSTATIC EXTRUSION

11 Extrusion

EXTRUSION DIE

12

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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

14

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

15

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

16

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

Example

17

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