extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect...

41
Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton 1 ver. 1 Extrusion

Transcript of extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect...

Page 1: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

1

ver. 1

Extrusion

Page 2: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

2

Overview

• Equipment• Characteristics• Mechanical Analysis

– direct extrusion– indirect extrusion

• Redundant work• Defects

Page 3: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

3

Geometry (90o die)

D1

D2

p

dead zone45o angle

Page 4: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

4

Equipment

Page 5: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

5

Extrusion

Page 6: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

6

Equipment

Page 7: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

7

Extrusions

Page 8: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

8

Page 9: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

9

Characteristics

• Similar to closed die forging• Forging

– slug (bulk) is forging– flash (extrusion) is waste

• Extrusion– extrusion (flash) is part– billet (bulk) is waste

Page 10: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

10

Types

• Direct• Indirect• Tubular• Hydrostatic• Cold Impact

Page 11: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

11

Types

1 – direct2 – indirect3 – heading (forging also)

Page 12: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

12

Flow types• “Laminar”• “Turbulent”

– redundant work– can bring outside of billet into

center– leaving the skin keeps outside

scale out of final extrusion

Page 13: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

13

Steel extrusion• Tprocessing = 2100 to 2400oF (1150 – 1315oC) • Tmelting = 2500 - 2800oF (1370 – 1540oC)• Die ≈ 400oF (205oC)• Obviously “Hot”

– above recyrstallization point• Lubricants

– glass (viscous lube ) 0.001” thick– MoS2

– graphite

Page 14: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

14

Mechanical Analysis

D1

D2

p

dead zone45o angle

externalfriction

internalfriction

x

Page 15: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

15

Assumptions

• Metal deforms uniformly– D1 to D2

• No redundant work• Can’t use slab analysis

– die angles too great– friction too high

• Dead zone sets up at 45 degrees

Page 16: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

16

p τfriction

Upper bound analysis• Work input by external forces

= plastic work expended

friction external

compress work toplastic

friction internalpressure

W

W

W W

&

&

&&

+

+

=

Page 17: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

17

Rate of work = Power

• Work rate = Power• Work rate = Area • stress • velocity

Page 18: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

18

Pressure work input• Power = A • p • v

– ram moves at velocity, vram

ramp vpDW ⋅⋅=4

21π&

Page 19: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

19

Internal “frictional” work input• Work determined by integrating rate of

frictional work dissipation at each cross section from D2 to D1 – τfriction = τflow– vi is in x-direction

DD + dD

dx

dL=dD/√245o

⋅= ∫

1

2

D

Diflowf DdLvW πτ&

Page 20: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

20

• Volumetric flow rate

– where D, Ai, vi are instantaneous

Internal “frictional” work input

iiram vAvAQ == 1

rami vDDv

21

=

Page 21: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

21

2

121 ln

2 DDDv

W flowramf ⋅=

τπ&

Internal “frictional” work input

∫=1

22

21D

D

flowramf D

dDDvW

τπ&

Page 22: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

22

Plastic work to compress input• Power = up x Area x velocity

• hence

ετεεσ flowfp YduvolumeEnergy 2/ ==== ∫

2

1ln2DD

ramflowpw vDDDW ⋅

⋅=∴

4ln4

21

2

1 πτ&

Page 23: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

23

Total work input (without external friction)

• reducing2

121

2

121

21

ln2

44

ln444

DDvD

DDvDvpD

flowram

flowramram

⋅⋅⋅+

⋅⋅⋅=⋅⋅

τπ

τππ

2

1ln414.32 D

Dpflow

⋅=τ

Page 24: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

24

Extrusion ratio (re)

• Reduction in area (RA) is large– it is not sensitive for classification

• Use re instead

RADDre −

=

=

11

2

2

1

Page 25: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

25

Extrusion pressure (without external friction)

2

2

1

2

1 ln707.1ln414.32

⋅=⋅=

DD

DDp

flowτ

eflow

rp ln707.12

⋅=τ

Page 26: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

26

Billet - wall friction

• Assume limiting case:friction stress = shear flow stress

τf = τflow

τflow

τflow

Page 27: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

27

Additional pressure due to billet - wall friction

xDDp flow ⋅⋅⋅=⋅

⋅∆ 1

21

4πτπ

1

22 D

xpflow

=∆τ

τflow

τflow

x

Page 28: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

28

Direct extrusion pressure

1

22222 D

xppppflowflowflowflow

x +=∆

+=ττττ

1

12

1

2ln707.12

2ln414.32

Dxrp

Dx

DDp

eflow

x

flow

x

+⋅=

+⋅=

τ

τ

Page 29: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

29

12

+===nKY

n

flowflowεστ

Strain hardening (cold – below recrystallization point)• Not plane strain (Tresca)

average flow stress:due to shape of element

Page 30: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

30

Example – 1-1

• You are forward, cold extruding Al-1100 (K = 140 MPa, n = 0.25), 10-cm diameter billet to a diameter of 5-cm at 1 m/min. The billet is initially 25 cm long

• The ram is made of a high-strength steel with a yield stress of 1.5 GPa.

• Determine the extrusion force and power.• Determine the safety factor for indenting the

ram.

Page 31: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

31

Example – 1-2

• The equations we use are:

12

1 2ln414.32 D

xDDp

flow

x +⋅=τ

12

+==nKY

n

flowετ

=

2

1ln2DDε

1+=== ∫ ∫ nKdKdu n

pεεεεσ

because

Page 32: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

32

Example – 1-3• We need to determine the dead-zone length to

subtract from the initial billet length.

• so X = 0.25 – 0.025 = 22.5 cm45°

2.5 cm5 cm2.5 cm

2.5 cm

Page 33: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

33

Example – 1-4• Substituting values

39.15

10ln2ln22

1 =

=

=

DDε

( ) MPanKY

n

flow 6.121125.0

39.11401

225.0

=+

×=

+==

ετ

+⋅×=

12

1 2ln414.32Dx

DDp flowx τ

MPaPextrusion 83410

5.2225

10ln414.36.121max, =

×

+⋅×=

Page 34: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

34

Example – 1-5

• Safety factor against indenting the ram– to determine the “press-fit” failure, we would

need the dimensions of the extrusion die and its material

8.1834.05.1

max,

===GPaGPan

extrusion

y

σσ

( ) MNAreaPF extrusionextrusion 6.61.04

10834 26 =××=×=π

kWmMNspeedFPower 110sec60min/min/16.6 =××=×=

Page 35: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

35

Redundant work

• ∆ = dm/L• dm = (D1 + D2) / 2• p = Qr σflow

p

D1

D2L (contact length)

Page 36: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

36

Redundant work factor (Backofen)(frictionless)

Qr =

Page 37: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

37

Defects• Surface materials drawn

into center– pipe, tail pipe

• Surface materials extruded– eliminate by leaving

skin

Page 38: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

38

Chevron Cracking

Page 39: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

39

Chevron cracking defect

• Hydrostatic tension– outer layer in compression– inner layer in tension, if

entire part is not plastic• eliminate by using a fluid

– hydrostatic compression– reduces friction

Page 40: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

40

Defects

• Surface speed cracking– high friction– temperature– speed

Page 41: extrusion - me.iitb.ac.inramesh/courses/ME649/extrusion.pdf · – direct extrusion – indirect extrusion • Redundant work • Defects. Prof. Ramesh Singh, Notes by Dr. Singh

Prof. Ramesh Singh, Notes by Dr. Singh/ Dr. Colton

41

Summary• Equipment• Characteristics• Mechanical Analysis

– direct extrusion• Redundant work• Defects