04_Cold_Forging_Bulk forming

Forming Technology

Bulk Forming

04_Cold Forging

4.1L04 – Cold Forging15/16

L04 – Cold Forging

IntroductionFundamental parameters, mechanics of extrusionComponent propertiesProcess variantsProcess sequenceProcess limits, tool design

Content




Content


Classification of extrusion processes according to DIN 8583

Extrusion Drawing Indentation RollingForging

Bulk forming

Cold forging/Extrusion Reducing

h

d1

d0

F

F d0 d1

d1

d0

F

PunchPunch

Punc

h

Workpiece

Work-piece

Die

Barextrusion


Basic extrusion processes

Punch

Die

Workpiece

Backward can extrusion

Ejector+ Counter punch

Punch

WorkpieceDie

Forward rod extrusion


Extrusion

Hot extrusionCold forging

- Forming above Trecrystallisation- For hard to form materials

(high strength steels, special qualities)- Low loads- Lower tool wear- Higher component size- Very high plastic strain- Low precision

- Room temperature- Mechanical properties- Limited component size - Excellent dimensional and geometrical

accuracy- No/marginal further treatment- Highest surface quality (Rz12- Rz25)- Strain hardening limits plastic strain- High loads

Hot extrusion partsCold forging parts


Advantages of extrusion

Hatebur

Machining Extrusion

Flange

Can

Connection piece

Example oil filter case: extruded single component compared to welded part out of three components

Extruded Welded




Content


Fundamental parameters

h

d1

d0

FPunch

Work-piece

DieIdeal equivalent plastic strain (extrusion strain):

Relative area reduction:

0

1

ln

AA

0 1

0

A

A AA

Initial cross-sectionalarea

Final cross-sectional area

20 04

A d

21 14

A d

Included cone angle / die angle

2


Mechanics of extrusion

2α = Die angle

FD = Friction force at the die

FS = Friction force at the shoulder

kf0 = Flow stress at the initialcross section

kf1 = Flow stress at the finalcross section

K. Lange

z

z

z

r

r

t

t~~

h

d1

r

z

d0

k f0

k f1

z r fk

FD

FS

1A

0A

F

CompressionTension


Typical force-displacement curve for forward rod extrusion

A:Process beginsA-B: Increase of force due to elastic deformations in toolsB-C: Material fills the die shoulderC-D: Force reduction due to change in tribological systemD-E:Quasi-steady-state extrusionD: Process ends

Punch Displacement h

Pu

nc

hF

orc

eF

Fmax

Extrusion Work

A

C

EB

D

Quasi-Steady-StateNon-Steady-

State

Punc

h fo

rce

F

Punch displacement h


Forces by Siebel for forward rod extrusion

total ideal friction shear

container + die shoulder

F F F F

ideal 0 fmF A k

Total punch force in forward rod extrusion:

die shoulderfriction 0 fm

2sin 2

F A k

containerfriction 0 0F d h k f

shear 0 fm2 tan3

F A k

Force necessary to overcome ideal (homogeneous) deformation

Force necessary to overcome die-shoulder friction

Force necessary to overcome container friction

Force necessary for internal shearing due to inhomogeneous deformation


Forward rod extrusion force components

0

1000

2000

3000

4000

10 30 50 70 90 110 130 150Included Cone Angle 2

Forc

e in

kN

Ideal ForceContainer FrictionDie Shoulder FrictionShear ForceTotal Force

0

1

50 mm30 mm

dd

120 mm0.1

h f0

f

k

k

0.25

320 MPa700 MPa

Material:

Included die angle 2α

Forc

e F

in k

N

Ideal forceContainer frictionDie shoulder frictionShear forceTotal force




Content


Steady-state property of extrusion

Steady-state properties

Billet Extrudate (Shaft)Die shoulder


Deformation of mesh lines at extrusion

1670

2185

21002130

2325

2520

2400

1940

2225

24902785

26201925

2090

2235

2275

1895

1620

1255

1620

2100

2100

2100

H V in N/mm 2

F.H. Feldmann

Hardness values before forming: HV = 900…1100 N/mm2

Hardness distribution after forming: HV in N/mm2


Central burst (chevron cracks)

Tekkaya & Yavuz

Material: 100Cr62 = 100o

= 0.25

Avitzur

Metaldyne Zell




Content


Process variants (solid body)

Backward extrusionForward rod extrusion

Lateralextrusion


Variants of forward extrusion

Forward hollowForward rod Forward can

Punch

Die

Work-piece

Mandrel

Ejector

Counterpunch

PunchWork-piece


Examples of forward extrusion

Kammerer, Stuttgart

Kammerer, Stuttgart

Kammerer, Stuttgart

Hirschvogel

Hirschvogel


Variants of backward extrusion

Backward rod Backward canBackward hollow

Punch

Die

Work-piece

Ejector+ Counter punch

Mandrel

Ejector + Counter punch

Punch

WorkpieceDie


Examples of backward can extrusion

Kammerer, Stuttgart

Ladish Co., Inc. Alutec


Variants of lateral extrusion

Hollow lateralRod lateral Can lateral

Punch

Die

Work-piece

Counterpunch

Mandrel

Mandrel

Counterpunch

Workpiece

Die

Kammerer, StuttgartKammerer, Stuttgart

IfU, Stuttgart


Examples of lateral extrusion

IfU, Stuttgart


Process combinations

Forward canBackward can

Forward rodBackward can

Forward hollowBackward can

Forward rodBackward rod

Backward canFlange upsetting

Backward canBackward can

Backward rodBackward can


Process combination of backward can and lateral extrusion

Kammerer, Stuttgart Kammerer, Stuttgart




Content


Process sequence

Cutting/shearing

Soft annealing

Lubricant applicationPhosphating(Bondering),

MoS2, Graphite

Cleaning

Extrusion (multi-stage)

Heat treatment

Subsequent treatment

Blank Phosphated& soap

Compression Backward canextrusion

Kammerer, Stuttgart


Video: extrusion (Alutec)

Real process of extrusion (aluminium):

Alutec




Content


Process limits of the main extrusion processes for economic tool life

Schuler

1.9

1.4

1.4

1.1

0.9

1.4

1.1

0.9

1.9

1.4

1.5

Not

iron

(Ni)

Mat

eria

l Aluminium (z.B. Al 99,5, )lead, zinc

Brass(CuZn37 - CuZn28)

more difficult to form(z.B. Cq35, 15MnCr5)most difficult to form(z.B. Cq45, 42CrMo4)

d0

d1

d0

h0

s0s1

d1

d0

h0

h2

s1Hollow forward ext. Backward can ext.

h0

LimitMaterial

Stee

l-M

ater

ial

Forward rod ext.


Tool design for forward extrusion

GrundplatteDruckplatte

StempelPreßbüchse

Schrumpfring

WerkstückZwischenplatte

GrundplatteDruckplatteAuswerfer

Base Plate

Pressure Plate

PunchDie

Shrink ring

Workpiece

Base PlatePressure PlateEjector

Intermed. Plate


Values for extrusion punch and die according to VDI 3138, sheet 2

R

0.4 to 0.6

R

Steels Light metals Steels Light metals

0.05 to 0.2 mm2 to 5 mm

R

**)

*) 2 to 5 mm0.05 to 0.2 mm

< 20°

2 to 3 mm

0.15 mm< 20°

up to 180°

R r>

*)**)

Depending on the workpiece dimensionsLowest load at 2α = 60°

Punch,Mandrel

Backward can extrusion Forward rod extrusion

Die

5° to 15°< 20°

3° to 5°

5° to 15°< 20°

0.15 mm0.5 to 3 mm 40° to 130°


Forward rod extrusion die

IfU, StuttgartIfU, Stuttgart


STRECON® Vari-Fit Die

Designed for precise adjustment of the inside diameter of the die

Aim: The ability to make parts with geometrical tolerances which are at least as good as those of the machined parts

Strecon, Soenderborg/Denmark


Materials for cold forging

Mildsteels

QSt32-3QSt34-3Cq 15etc.

Case hardening steels(EN 10084)

C10EC15E15Cr316MnCr520MoCr415CrNi6

Tempered steels(EN 10083)

C22EC35EC45E34Cr441Cr442CrMo4

Non-ferrous metal

Some alloys of aluminium and copper

Source: doldgmbh.de


Appendix: German for production engineers

English German English GermanCold forging Kaltfließpressen Die Shoulder Matrizenschulter

Reducing Verjüngen Steady State Stationärer ZustandForward Rod Extrusion

Voll-Vorwärts-Fließpressen Damage Schädigung

Backward Can Extrusion

Napf-Rückwärts-Fließpressen Hardness Härte

Lateral Extrusion Quer-Fließpressen Residual Stresses Eigenspannungen

Grain Flow Faserverlauf Ejector Auswerfer

Die Matrize Shrink Ring Schrumpfring


Literature

Lange, K.: Umformtechnik – Band 2: Massivumformung. Springer-Verlag, Berlin, 1988, ISBN 3-540-17790-4.

Lange, K.; Kammerer, M.; Pöhlandt, K.; Schöck J.:

Fließpressen: wirtschaftliche Fertigung metallischer Präzisionswerkstücke. Springer, 2007

VDI-Richtlinien Teil 2, Register 5:3138 Kaltfließpressen von Stählen und NE-Metallen3186 Werkzeuge für das Kaltfließpressen von Stahl

ICFG DS 1/70 Calculation of pressures for cold forward extrusion of steel rods. Ins deutsche übersetzt und veröffentlicht in VDI-Richtlinie 3185, Blatt 1

ICFG DS 9/82 Determination of pressures and loads for warm extrusion of steels. Reprint in: ICFG 1967-1982 Objectives, history, Published Documents. Bamberg: Meisenbach, 1992, pp. 15-17

Altan, T.; Ngalie, G.; Shen, G.:

Cold and Hot Forging – Fundamentals and ApplicationsISBN 0-87170-805-1

Hosford, W.; Caddell, R.: Metal Forming: Mechanics and Metallurgy, Cambridge University Press, 2007, ISBN 0-5218-8121-8.