Forming - Bulk Forming - RWTH Aachen University of Forming Technology: Bulk Forming – Sheet Metal...

1

© WZL/Fraunhofer IPT

Forming - Bulk Forming

Manufacturing Technology II

Lecture 4

Laboratory for Machine Tools and Production Engineering

Chair of Manufacturing Technologies

Prof. Dr.-Ing. Dr.-Ing. E. h. F. Klocke

Seite 1© WZL/Fraunhofer IPT

Outline

Introduction

Cold forming

Warm forming

Forging

2


Casting Forming Cutting Joining Coating Changing of Material properties

Compressive Forming

Tension Com-pressive Forming

TensilForming Bending Shear

Forming Severing

TranslateTwistIntersperse

Manufacturing Processes

Open die forgingClosed die forgingCold extrusionRod extrusionRollingUpsettingHobbingThread rolling

Stretch formingExtending ExpendingEmbossing

Deep drawingIroningSpinningHydroformingWire drawingPipe drawingCollar forming

With linear tool movementWith rotational tool movement

ShearingFine BlankingCutting with a single bladeCutting with twoapproaching bladesSplittingTearing

IntroductionMethods of Forming – Classification DIN 8580 ff


Sheet metal forming

no or low unwanted changing of the original wall thickness

smaller deformations

smaller material strain hardening

lower forces

than by bulk forming procedures

IntroductionProcess of Forming Technology: Bulk Forming – Sheet Metal FormingBulk forming:

large changing of cross section and dimension

large form modification

large material strain hardening

high forces

high tool stresses

3


Bulk forming

massivesemi-finished material

component

IntroductionWhat is Bulk Forming?


semi-finished part component

Cutting

1,3 kg

Forming

0,4 kg

IntroductionAdvantages of Bulk Forming

componentbasic workpiece

4


bulk forming allows function integration e.g. stability and leak tightness

Joiningof singel-piece

joined by welding

flange

can

fitting

Function integrationby bulk forming

formed by extrusion

Introduction Advantages of Bulk Forming


Outline

Introduction

Cold forming

– Introduction

– Upsetting

– Extrusion

Warm forming

Forging

5


fcc

bcc

recrystallizing

Cold formingIron-Carbon Diagramm

Carbon content in weight percent

Cermentite content in weight percent


workpiece temperatur / °C

Stra

in j

Flow

stre

ss k

f/ M

Pa

Laye

r of s

cale

/ µm

Cold forming Material Properties

high flow stresses and low achievable strain by classic steel materials

6


Cold forming Advantages and Disadvantages of Cold Forming

Cold FormingAdvantages:

low tool material costslow influence of forming velocityno energy costs for heatingno dimension faults caused by dwindlinghigh surface qualityincreasing strength of the component

Disadvantages:high forceslimited plastic strain


forming cold warm hotworkpiece weight 0,001 – 30 kg 0,001 – 50 kg 0,05 – 1.5plasticity φ < 1,6 r<4 r<6finishing effort less low high

semi-finished part Cold forming

Cold forming Efficiency

(for classic forming steels)

with cold forming processes a good workpiece quality can be reached by low strain

7


Forming process IT-statement like DIN ISO quality

5 6 7 8 9 10 11 12 13 14 15 16

Cold extrusion

Warm extrusion

Hot extrusion

centerline average Ra / µm

0,5 1 2 3 4 6 8 10 12 15 20 25 30

achievable with special proceedings achievable without special proceedings

Cold forming Efficiency

small shape, dimension and position tolerances as well as good surface qualities are possible


extrusion full extrusion hollow extrusion cup extrusion

forwardextrusion

backwardextrusion

radialextrusion

before after

Cold forming Forming Processes

a: punch, b: die, c: workpiece, d: ejector, e: counter punch, f: spike

8


workpieceinsertion

compression extrusion ejection

punch

workpiece

cavity

ejector

die

Cold forming Full Forward Extrusion

production of a pin


workpiece insertion

compression extrusion ejection

punch

workpiece

die

ejector

Cold forming Cup Backward Extrusion

production of a cup

9


workpieceinsertion

closing ofthe die

extrusion ejection

upper punch

workpiece

lower dielower punch

upper die

production of a cardan joint

Cold forming Radial Extrusion of a Cardan Joint


Cold forming Typical Cold Formed Components

gear shafts

tubes

denticulations

screws

Hirschvogel Hirschvogel

FuchsSchraubenwerk

10


Prozesskette

Cold forming Process Chain of a Screw Production

almost all screw geometries are produced by extrusion processes.

ejector

upper die

die

finished part


blank full forwardextrusion

full backwardextrusion

radialextrusion

Cold forming Process Chain of a Gear Shaft Production

the production of components is usually charactarized by a combination of different extrusion processes

11


Cold forming Film: Cold Extrusion of a Gear Shaft


Cold forming Cracks by Radial Extrusion Processes

during upsetting or radial extrusion processes surface cracks can appear on the collar surface

12


Cold forming Crack Reduction by Superposition of Compressive Stresses

punchgasketdieworkpiecepressure mediumrelief pressure valve

tearing could effectively be shift to higher strains by superposition of compressive stresses


without axialpressure superposition

with axialpressure superposition

max. availabledeformation

fixed fixed

Cold forming Crack Prevention by Superposition of Compressive Stresses

superposition of compressive stresses can be realized by modifying the tool concept

13


Cold forming Chevron Cracks by Full Forward Extrusion


3. forming step real workpiece

Cold forming Chevron Cracks by Full Forward Extrusion

a unfavourable dispersion of the interior material generates cracks

Chevrons

FEM-Simulation

DEFORM

14


bucking upsetting indirect cup extrusion

cutting radial extrusion burr cutting calibration

recrystallization recrystallization recrystallization

Cold forming Phases of Production of a Bevel Gear

achievable deformation can be increased by recrystallization


Outline

Introduction

Cold forming

Warm forming

Forging

15


Warm formingIron-Carbon Diagram

fcc

bcc

recrystallization




Warm forming Material properties

workpiece temperatur / °C

reduction of flow stress and increase of the avchievable strain

Stra

in j

Flow

stre

ss k

f/ M

Pa

Laye

r of s

cale

/ µm

16


Warm forming Advantages and Disadvantages of Warm Forming

Warm formingAdvantages:

strengthening of the workpiecesmall range of tolerance caused by dwindlinggood surface quality

Disadvantages:energy input for heatinghigh flow stresses

Hirschvogel


forming cold warm hotworkpiece weight 0,001 – 30 kg 0,001 – 50 kg 0,05 – 1.500 kgplasticity φ<1,6 j<4 j<6finishing effort less low high

semi-finished part cold forming

warmforming

Warm forming Efficiency

17



5 6 7 8 9 10 11 12 13 14 15 16

Cold extrusion

Warm extrusion

Hot extrusion


0,5 1 2 3 4 6 8 10 12 15 20 25 30

achievable with special proceedings achievable without special proceedings

Warm forming Efficiency

mean shape, dimension and position tolerances as well as mean surface quality are possible


Warm forming Typical Warm Formed Components

hinge flange cylinder injector

Hirschvogel Hirschvogel

Audi

18


Outline

Introduction

Cold forming

Warm forming

Forging

– Introduction

– Open die forging

– Closed die forging

– Ring rolling


ForgingIron-Carbon Diagram

fcc

bcc

recrystallization



19


Forging Material Properties

Workpiece temperatur / °C

low flow stress and high achievable strain

Stra

in j

Flow

stre

ss k

f/ M

Pa

Laye

r of s

cale

/ µm


Forging Advantages and Disadvantages of Forging

ForgingAdvantages:

less efforthigh plasticity

Disadvantages:high energy input for heatinghigh material costs for toolsdimension faults by shrinkagematerial loss and finishing caused by tinder

20


forming cold warm hotworkpiece weight 0,001 – 30 kg 0,001 – 50 kg 0,05 – 1.500 kgplasticity φ<1,6 j<4 j<6finishing effort less low high

initial state coldforming

warmforming forging

Forging Efficiency



5 6 7 8 9 10 11 12 13 14 15 16

Cold extrusion

Warm extrusion

Hot extrusion


0,5 1 2 3 4 6 8 10 12 15 20 25 30

achievable witht special proceedings achievable without special proceedings

Forging Efficiency

low shape, dimension and position tolerances as well aslow surface quality possible

21


Forging Heating Methods

Heating in furnaces:furnaces are heated by gas, oil or electricityheat transmisson to the workpiece by radiation and convection

Heating by induction:heat in the workpiece rim is generated by electromagnetic induction by eddy current formation

Conductive heating:heating by high-frecuency current with direct workpiece contact

Furnace

Inductive heating facility

inductive and conductive heating reduces the production of primary tinder as a result of the heating rate


Forging Tinder

if Ironmaterials are heated above 600° C under the influence of oxygen, ironoxid will be generated on the surface, which is called tindertinder peels away of the workpiece during the forming processthe results are loss of material, surface marking and tool wear

Saarstahl

22


ForgingGeneration of Tinder During Forging Operations


Forging Processes

Saarstahl

streching and upsetting are the main processes of open die forging

Streching

Freeforming

UpsettingRotaryswaging

Latidudinalforming

Driving Free curvingby streching

Thinning

Smoothing BulgingCorrective streching Surfacing UpendingForging a step

by streching

23


upsetting

streching

flat back gage acuminate back gage round back gage

Forging Processes – Open Die Forging

Saarstahl

Saarstahl

simple tool geometries are used for open die forging processes


Freiformschmieden

Forging Process cycle

simple tool geometries can produce complex workpiece geometries

round forging

upsetting

streching

upsetting

strechingforging

forging and shearingwastage

blank

forging a step

forging a step

24


Forging Open Die Forging

Saarstahl


a: tensile strengthb: strain at fracture Zc: ductile yield Ad: yield strength Rpe: notch impact strength ak

parallel vertical direction of deformationacross the direction of deformation transition direction across alongdecrease by material impurity

Streching degree lR1 2 3 4 5 6 7 8

Forging Material Properties Override

Saarstahl

by increasing the streching degree the material poperties can be improved

25


Forging Film: Open Die Forging


Upper die

Lower die

Lower die

Upper die

Forging part

Forging part

Burr cavity

Forging Closed Die Forging

Forging without burr:• low forming forces• complete material utilization• max. permitted volume fluctuation 0,5%• exact workpiece positioning required

Forging with burr:• less standards on workpiece volume

fluctuation• no exact workpiece positioning required• the removal of the burr needs an extra

process step

26


Forging Stages of Closed Die forging

crankshaft

connection rod

hinge bearing

an effective preform production is the key for short production chains


Forging Closed Die Forging

27


1 - wear / adbrasion

2 - thermal fatigue / crack formation

3 - mechanical fatigue / crack formation

4 - plastic deformation

2

1/3/4

1/4

1

3 1/41 2

Forging Die Wear

the main reason for tool change is the abrasion on edges and cracks in cavitations


Forging Wear in the Burr Channel Area

massive burr formation as reason for abrasion in the burr channel area

abrasion

28



Massive flash formation as reason for abrasion in the burr channel area



Massive flash formation as reason for abrasion in the burr channel area

29


Forging Film: Closed Die Forging with Forging Hammer


Forging Film: Closed Die Forging of a Crankshaft

30


centering rollaxial rolls ring main rollpin roll

Forging Processprinciple: Radial Axial Rolling Mill

by ring rolling small output rings can be formed to big, thin-walled, and profiled rings


Forging Ring Rolling

31


Possible profiles

Forging Possible Ring Geometries

by profiling the pin- and/or main roll many different ring geometries can be produced


Kleine Ringe Schmiedjournal

Forging Dimensions

big and small rings can be produced by ring rolling

32


Walzen

Ringwalzen

Forging Typical Components

SMS Eumuco


Forging Film: Axial Radial Ring Rolling

Forming - Bulk Forming - RWTH Aachen University of Forming Technology: Bulk Forming – Sheet Metal...

Documents

Transcript of Forming - Bulk Forming - RWTH Aachen University of Forming Technology: Bulk Forming – Sheet Metal...