Stamping Simulation Model Stamping Simulation Model for Titanium Sheetfor Titanium Sheet

Y. Y. ItamiItami, K. , K. TokunoTokuno and T. and T. OdaOdaNipponNippon Steel CorporationSteel Corporation

Titanium 2006 San Diego, CAOctober 3, 2006

Table of contentsTable of contents

1)IntroductionExamples of stamping application

2) Considerable Condition on titanium stamping simulation

3)Development of stampingsimulation model

4)Conclusion

Stamping application for I.T. body partsStamping application for I.T. body parts•• Stamping requirement at customersStamping requirement at customers

1) Dimensional precision forming2) Difficult forming

Application areas are widening & increasing !However, there are some difficulties in

titanium stamping

Recent example of titanium stamping products

Sony Network walkman NW-MS70D 2003/02

SONY Linear PCM recorder PCM-D1 2005/11

Recent example of titanium stamping products

Recent example of titanium stamping parts

Sony net walkman

Stage #1 #2 #3 #4

Difficult forming: Increasing stamping stages

Examples of precision forming Sharp corner

They used Nippon Steel material

Dents portion

Recent example of titanium stamping parts

1.Mechanical property

2.Lubrication

3.Die design (Process design)

Considerable condition Considerable condition 　　　　on titanium stamping on titanium stamping simulationsimulation

1. Mechanical property

Plasticity anisotropy

0

100

200

300

400

500

600

700

0 0.1 0.2 0.3 0.4 0.5

　True strain　/

True

　st

ress

　/M

Pa

Longitudinal 0 deg.45 deg.90 deg.

Anisotropic work-hardening of pure titanium

Experiment equipment of yield-surface measurement

Laser CCD for

Curvature, Radius measurement

CCD Camera for

Longitudinal Strain measurement

Axial Force

Internal Pressure

Stress ratio control system

Yield surface of titanium (ｒ0＝1.7ｒ45＝4.3ｒ90＝4.8)

-200

0

200

400

600

800

1000

-200 0 200 400 600 800 1000

M eridional stress σφ /M Pa

Circumferential stress σ

Θ /MPa

0.01

0.02

0.05

0.1

0.15

0.01

0.02

0.05

0.1

0.15

εeq

Steel

σθ σθ

σφ

σφ

• Lubricating method( reducing friction )

• Life of die(preventing crack initiation ,

seizure, galling)

2. Lubrication Conditions2. Lubrication Conditions

Effect of lubrication on forming height

No lubrication Normal lubrication

Good lubrication

Height=9mm Height=11mm

Height=14mmErichsen cup test :Sheet thickness= 0.5mm

3.Die design (Process design)3.Die design (Process design)

““Try and ErrorTry and Error”” increases costsincreases costs

Conner radius, Clearance , Blank Hold Force(BHF), etc

Shock-line

a) Clearance: small

Material

Punch

b)Clearance: large

No shock-line

Die

Effect of clearance on shock-line

• Deformation behavior of titanium1)Large plastic anisotropy2)Anisotropic work-hardening

(Steel follows isotropic hardening rule )

• Frictional resistanceEffect of friction coefficient

• Full 3D FEM simulationConsideration of thickness

direction stress

Development of stamping Development of stamping simulation model for titanium sheetsimulation model for titanium sheet

Measuring yield-surface

Constitutive equation

3D elastic-plasticFEM simulation

Development of stamping Development of stamping simulation model for titanium sheetsimulation model for titanium sheetConventional model• Plane stress model σz=0 and τyz =0 and τyz=0

anisotropic work hardening not considered

Development model• Full 3-dimensional model a1(σy-σz)2＋ a2(σz-σx)2 + a3(σx-σy)2

+a4τyz2+ a5τyz

2+ a6τxy2=σ2

anisotropic work hardening consideredThickness direction stress considered for ironing

σzσx

σy

σx

σy

Meshing of 3D FEM simulation model

5 divisions in thickness direction

t=0.5mm

CanningShock line

Experiment 3D-FEM simulation

Square-shell deep drawing

An example of stamping titanium

Deformation of titanium sheet (Animation )

Thickness direction strain distribution (Animation)

Forming- load simulation during stamping

0

10

20

30

40

0 10 20 30Forming height /mm

Stam

ping

load

/ k

N

MeasureCalculation

Flange-profile simulation of titanium sheetH=0mm 20mm10mm 30mm

Calculation Experiment3-dimensionalshape measurement

9045

0deg

Thickness distribution of square deep-drawing（H=30mm)

Calculation Experiment

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0 50 100 150Distance from center /mm

Thic

knes

s /m

m45deg.90deg.0deg.

B.H.F=10kNµ=0.03

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0 50 100 150Distance from center /mm

Thic

knes

s /m

m

45deg.90deg.0deg.

B.H.F=10kN

The application and The application and solution of titanium stampingsolution of titanium stamping

Part design

Process design

Forming validation

Simulation modelSimulation modelPredict and solve difficulties:• Material mechanical properties• Lubrication • Die design

Recommend::• Die-design• Stamping condition • Materials

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• Digital camera body parts

Photokina world imaging in Köln 26.09.2006

Debut

ConclusionConclusionIn the FEM simulation, both anisotropy of

plasticity and anisotropic work hardening model were adopted for high precision calculation of titanium stamping.

• Thickness strain distribution and deformation of blank (material plastic flow from flange)　caused by stamping were consistently calculated using the FEM model.

• The results were in good agreement with behaviors of square-shell deep drawing of pure titanium sheets observed in experiments.