11 selected research resu

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© Copyright Engineering Research Center for Net Shape Manufacturing, 2004. All rights reserved.1

Selected Research Results in Stamping,Hydroforming and Forging

Selected Research Results in Stamping,Hydroforming and Forging

byDr. Taylan Altan, Professor and Director, [[email protected]]

Engineering Research Center for Net Shape Manufacturing (ERC/NSM)Columbus, Ohio, USA

Phone: 614-292-6468, Fax: 614-292-7219www.ercnsm.org

Prepared forInternational Conference

INNOVATIONS IN METAL FORMING23-24 September, 2004 - Brescia, Italy

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OutlineOutline

IntroductionIntroductionStamping ResearchStamping ResearchHydroforming ResearchHydroforming ResearchForging ResearchForging ResearchSummary and Future Outlook Summary and Future Outlook



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Introduction

Stamping Hydroforming MachiningForging

Research for Industry and Government

1) Material characterization <flow stress & formability>2) Tribology < friction,lubrication & wear >3) Process Modeling/Tool and Process Design4) Short Courses/Training for Industry and Students

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StampingStampingResearchResearch



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ERC/NSM Activities in StampingERC/NSM Activities in Stamping

1. Materials1. MaterialsDetermination of material flow stress (true stress - true strain) data at roomtemperature, under bi-axial state of stress, using Viscous Pressure Bulge test.

2. Tribology (Friction, Tool Wear)2. Tribology (Friction, Tool Wear)Determination of friction coefficient for use in FE simulations, using LimitingDome Height, Modified Limiting Dome Height, and Drawing and Ironing tests.Performance evaluation of various stamping lubricants (at room and elevatedtemperatures) to determine the best suitable lubricant for a particularapplication.

3. Process Modeling / Tool and Process Design3. Process Modeling / Tool and Process DesignDetermination of optimum constant / variable blank holder force profiles forstamping using FEMDetermination of blank shapes and process sequence for progressive diestamping using FEMDesign of warm sheet forming process of Mg & Al alloy sheets using FEMDesign of mechanical joining process (clinching / crimping) using FEM

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Real time measurement of instantaneous pressure and domeheight

Potentiometer

PressureTransducer

PunchLower

Die

Upper Die

ViscousMedium

Cushion Force

Moves with pressram

Moves with pressram

Stationary

Viscous Pressure Bulge Test- Sheet materials -



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Material : 1050 steel

0.0

200.0

400.0

600.0

800.0

1000.0

1200.0

1400.0

1600.0

0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350

True Strain

T r u e

S t r e s s

[ M P a

]

Tensile test

VPB test

Larger strains compared to tensile test

Flow Stress Curve

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Initial blank

(Circular blank with hole at thecenter)

Stretched blank

(Change in hole diameter)

Punch

Die

Clamping ring

Tribology/Modified LDH test



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Drawing and Ironing Test - Principle and Tooling

Tribology/Drawing and Ironing Test

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Issues with Multi-point Cushion Systems

..…

BHF for cushion pin 1

0

80

160

240

320

400

480

0 10 20 30 40 50 60Punch Stroke (mm)

B l a n

k H o

l d e r

F o r c e

( k N

?


0

80

160

240

320

400

480

0 10 20 30 40 50 60Punch Stroke (mm)

B l a n

k H o

l d e r

F o r c e

( k N

?Problem: How to determine the variation of

BHF for each cushion pin ?

Cushion pin 15

Cushion pin 1

FE Simulation for Variable BHF determination



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Inputs required

FEA SoftwareFEA Software(PAM-STAMP, LS-DYNA)

SoftwareSoftwaredeveloped atdeveloped at

ERC/NSM for BHFERC/NSM for BHFdeterminationdetermination

• Tool geometry (CAD)• Material properties• Process conditions

0

80

160

240

320

400

480

0 10 20 30 40 50 60Punch Stroke (mm)

B l a n

k H o

l d e r

F o r c e

( k N )


0

80

160

240

320

400

480

0 10 20 30 40 50 60

Punch Stroke (mm)

B l a n

k H o

l d e r

F o r c e

( k N )


0

80

160

240

320

400

480

0 10 20 30 40 50 60Punch Stroke (mm)

B l a n

k H o

l d e r

F o r c e

( k N )

BHF for cushion pin n

• Quality control parameters(wrinkling, thinning)

• Forming depth of the part• No. of cushion cylinders (n)

• Variation of BHF required− Constant in location and stroke− Constant in location, variable with stroke− Variable in location, constant with stroke

− Variable in location and stroke

FE Simulation for Variable BHF determination

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Stage 1

Stage 2

Stage 3

Stage 4

Stage 5

Stage 6

Stage 7

Stage 8

Stage 1

Stage 2

Stage 3

Stage 4

Stage 5

Stage 6

Stage 7

Stage 8

Process Modeling/Progressive forming sequencedesign for deep drawing of round parts



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Sheet Hydroforming of Large Al Alloy Reflectors

Sheet Hydroforming of Large Al Alloy Reflectors

• Design sheet hydroforming process to manufacture large reflectors (6m/12m Ф )

to meet the desired accuracy on the inner surface.

• Identify locations for cutting and assembly of large reflectors to reduce

distortion due to residual stresses.

• Quantify effect of process parameters such as (material properties, friction,

initial sheet flatness, clamping methods) on hydroformed part dimensions.

UpperDie

LowerDie

Sheet

Finite element modelSchematic of hydroforming operation

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© Copyright Engineering Research Center for Net Shape Manufacturing, 2004. All rights reserved.14 AIDA & ERC/NSMPtU Darmstadt

Elevated Temperature

Hydraulic Bulge Test

Mg & Al Sheet Forming at Elevated

Temperature

Warm Forming Tool

• Hydraulic bulge tests at various temperatures and strain rates to determine theflow stress of Mg AZ31-O alloy.

• Determination of optimum process variables and tool temperatures to obtain thehighest possible Limiting Draw Ratio by modifying initial temperatures of thepunch, die, die ring and blank holder, initial blank temperature and ram dwelltime, and blank holder force



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Servo Motor PressServo Motor Press

AIDA Digital servo former AIDA Digital servo formerCourtesy : Aida Engineering, Japan

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Process Modeling/Design of Fastener Clinching

Objective: Leak proof assembly (without holes) of fastener with sheet

Design requirement : Ability to withstand ~ 10 kN force

Final clinched assemblyGeometry at start of clinching

Punch

Fastener Fastener



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Process Modeling/FE Simulation of Fastener Clinching

Click to view animation

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HydroformingHydroformingResearchResearch



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ERC/NSM Activities in Tube HydroformingERC/NSM Activities in Tube Hydroforming

1. Materials1. MaterialsDetermination of material flow stress data for tubular materials withHydraulic Bulge Test at room temperatureDetermination of material flow stress data at elevated temperatures

2. Tribology (Friction, Tool Wear)2. Tribology (Friction, Tool Wear)Improvement of Tribological Conditions in Tube Hydroforming by UsingEnvironmentally Friendly Lubricant Systems and Textured Tubes

Viability of the Twist Compression Test for Screening Tube HydroformingLubricants

3. Process Modeling / Tool and Process Design3. Process Modeling / Tool and Process DesignSimulation of T shape tube hydroformingDesign of warm hydroforming process of Magnesium and Aluminum alloytubes.

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Materials/Flow Stress and Formability -Hydraulic Tube Bulge Test -

Hydraulic Bulge Test Equipment

Determination of flow stress of tubes for Hydroforming



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Tribology/Friction and Lubrication

Friction conditions at different contact locations

Due to different tribological conditions at the Guiding, Transition andExpansion zones, different lubrication tests are needed.

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Load Cell

PressureTransducer

Rod

Tube

Die-Insert

pi

Fa Fa

Ff pi

Fa Fa

Ff

saxsax

FFR FFR FFR FFR

G o o d

l u b r i c a

t i o n

B a d l u

b r i c a

t i o n

Tribology/Tooling for LubricationTest - Guiding Zone -



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Tribology/Tooling for LubricationTest - Expansion Zone -

Pear Shaped Expansion Test

68

68.5

69

69.5

70

70.5

71

71.5

72

72.5

Lub A Lub E Lub D Lub B No Lub

Lubricants

P r o

t r u s

i o n

h e

i g h t P H [ m m

]Specimen material SS304

Increasing interface friction

PH

Increasing interfacefriction

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Tribology/ Twist CompressionTwist CompressionTest (TCT)Test (TCT) -- Principle of OperationPrinciple of Operation --

F r

T

*=µ

r

T

F

Before Test After Test

Material: AISI 1010 CRPressure: 500 bar

Sliding Velocity: 17 mm/sSliding Length: 160 mm



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Process Modeling /THF of T ShapeProcess Modeling /THF of T Shape

Part Name:Part Name: T fittingT fitting

Software:Software: DEFORM3DDEFORM3D

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Process Modeling /THF of T ShapeProcess Modeling /THF of T Shape

Part Name:Part Name: T fittingT fitting

Software:Software: DEFORM3DDEFORM3D




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HydraulicCylinder

CylinderRod

Coolingadaptor

Clamping Die[Lower]

FormingDie

PunchTube

Clamping Die[Upper]

Prototype of Warm Tube Hydroforming System for Phase I

Tube Hydroforming System for Al andMg Tubes at Elevated TemperatureTube Hydroforming System for Al andMg Tubes at Elevated Temperature

This project isdivided into 2phases as follows:

Phase I: Feasibilitystudy for warm tubehydroformingprocess(COMPELTED )

Phase II: Design ofa new and practical

warm tubehydroformingsystem (INPROGRESS)

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ForgingForgingResearchResearch



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ERC/NSM Activities in ForgingERC/NSM Activities in Forging

1. Materials1. MaterialsDetermination of material flow stress data by cylinder compression tests.

2. Tribology (Friction, Tool Wear)2. Tribology (Friction, Tool Wear)Performance evaluation of cold forging lubricants.

3. Process Modeling / Tool and Process Design3. Process Modeling / Tool and Process Design• Prevention of Ductile Fracture (Chevron Cracks)• Three Dimensional Finite Element Simulation of Orbital Forming of

Spindle/Bearing Assembly

• Microforming of Medical Devices

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Compression Tooling

Samples before & after

the compression test

Materials/Flow Stress- Cylinder Compression Test -

Upper plate

Carbideinserts

Load-cell

Lower plate



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Materials/Flow Stress- Cylinder Compression Test -

K= 117 Ksi, n=0.18 determined by least square fit

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Tribology/ Double Cup ExtrusionTooling

Double cup extrusion test – Principle & Tooling

h 1

h 2



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Ring Compression Test at ElevatedTemperature

Ring Compression Test at ElevatedTemperature

Ring compression tests were conducted at elevated temperature toRing compression tests were conducted at elevated temperature todetermine the effect of temperature on lubricant performancedetermine the effect of temperature on lubricant performance

Dry (top) Lubricant (bottom)Dry (top) Lubricant (bottom)TD,BD,Ring:150TD,BD,Ring:150 °°CCSpeed: 65mm/secSpeed: 65mm/sec

ID: 18.71 mm (top), 19.98 mm (bottom)ID: 18.71 mm (top), 19.98 mm (bottom)RC3RC3

Lubricant (top & bottom)Lubricant (top & bottom)TD,BD,Ring:150TD,BD,Ring:150 °°CC

Speed: 65mm/secSpeed: 65mm/sec

ID: 19.81 mm (top & bottom)ID: 19.81 mm (top & bottom)RC2RC2

Lubricant (top & bottom)Lubricant (top & bottom)TD:150TD:150 °°CC BD, Ring: 25BD, Ring: 25 °°CCSpeed: 65mm/secSpeed: 65mm/sec

ID: 19.78 mm (top), 20.56 mm (bottom)ID: 19.78 mm (top), 20.56 mm (bottom)RC1RC1

Final Ring GeometriesFinal Ring GeometriesTest ConditionsTest Conditions

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Process Modeling/Defects in Forward Extrusion

Process Modeling/Defects in Forward Extrusion

Prediction of chevron cracking in forward extrusion



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Process Modeling/Prediction of Chevron Cracks

Process Modeling/Prediction of Chevron Cracks


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Process Modeling/Orbital Forming


Assembly of inner race on a forged shaft



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Process Modeling/Micro - Forming


Microforming of cutting blades(Part thickness = 0.1 mm; flash thickness = 0.01 mm)



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Summary and Future Outlook Summary and Future Outlook

With the aid of experiments and FEM analysis ERC/NSM has helpedWith the aid of experiments and FEM analysis ERC/NSM has helpedachieve continuous process and product improvement in the fieldsachieve continuous process and product improvement in the fields ofofStamping, Hydroforming and Forging.Stamping, Hydroforming and Forging.

ERC/NSM has advanced experimental and computational capabilitiesERC/NSM has advanced experimental and computational capabilities forformetalforming research.metalforming research.

ERC/NSM has been and will be involved in conducting cutting edgeERC/NSM has been and will be involved in conducting cutting edgemetalforming research in association with industry and governmenmetalforming research in association with industry and governmen t.t.

11 selected research resu

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