IFG Workshop Impulse Forming May 7 th , 2013 Gent, Belgium - - PowerPoint PPT Presentation

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IFG Workshop Impulse Forming May 7 th , 2013 Gent, Belgium - - PowerPoint PPT Presentation

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IFG Workshop Impulse Forming May 7 th , 2013 Gent, Belgium Determination of suitable driver materials for electromagnetic sheet metal forming Soeren Gies Agenda Introduction Effect of driver sheets State of the art Experimental setup and

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Soeren Gies

Determination of suitable driver materials for electromagnetic sheet metal forming I²FG Workshop

Impulse Forming

May 7th, 2013 Gent, Belgium

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Introduction Effect of driver sheets State of the art Experimental setup and procedure Results Summary and Outlook

Agenda

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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Introduction Effect of driver sheets State of the art Experimental setup and procedure Results Summary and Outlook

Agenda

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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Introduction

Objective: Electromagnetic forming of stainless steel 1.4301 and 1.4509 Challenge: Low electrical conductivity of stainless steel Solution: Use of driver sheets

Copper Aluminum Steel Stainless steel CU-ETP CU-DHP EN AW-1050A EN AW-5083 DC06 1.4301 1.4509 57 MS/m 43 MS/m 34 MS/m 16 MS/m 8 MS/m 1.5 MS/m 100% 75% 60% 28% 14% 2,6%

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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Working principle of driver sheets:

Introduction

Driver sheet Workpiece Upper tool

(Forming die)

Lower tool

(Flat working coil)

Coil winding Coil winding tD tW

Introduction Driver Sheets SotA Setup and Procedure Results Summary Workpiece: 1.4301, tW = 0.8 mm Driver: Aluminum, tD=0.8 mm

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Introduction Effect of driver sheets State of the art Experimental setup and procedure Results Summary and Outlook

Agenda

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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Effect of driver sheets

Energy supply Charging energy Forming energy Forming- result electromagnetic system (1) mechanical system (2) Coil energy Kinetic energy magn. pressure

Ohmic heating Magnetic flux lines in the air Elastic energy in the die

Use of driver sheets causes two opposing effects in the energy conversion sequence

Introduction Driver Sheets SotA Setup and Procedure Results Summary

Energy conversion sequence: Risch, 2009

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Effect of driver sheets

Energy supply Charging energy electromagnetic system (1) mechanical system (2) Kinetic energy magn. pressure

Ohmic heating Magnetic flux lines in the air Elastic energy in the die

Coil energy Forming energy Forming- result

Forming energy driver sheet

Trade off: higher magnetic pressure vs. additional forming energy

Use of driver sheets causes two opposing effects in the energy conversion sequence

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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MAX

Effect of driver sheets

Use of driver sheets is beneficial if the following condition is fulfilled:

Additional kinetic energy Ekin Additional forming energy for driver Eform

Optimum

Question: Which driver material and which driver thickness tD maximize the energy ratio?

Additional kinetic energy Additional forming energy for driver

Self-evident consequences:

  • High electrical conductivity Ekin
  • Low yield strength

Eform

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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Introduction Effect of driver sheets State of the art Experimental setup and procedure Results Summary and Outlook

Agenda

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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State of the art

Scientific investigations using driver sheets:

– Seth et al. (2004)

  • Workpiece:

Low-alloy carbon steel, tW = 0.1 mm – 0.38 mm

  • Driver:

Aluminium EN AW-6111 T4, tD = 1 mm

– Li et al. (2012)

  • Workpiece:

Ti-6Al-4V, tW = 0.5 mm

  • Driver:

CU-DHP, tD = 0.5 mm

– Andersson and Syk (2008)

  • Workpiece:

X5CrNiMo17-12-2, tW = 0.25 mm / DP600, tW = 0.7 mm

  • Driver:

Copper, tD = 0.6 mm

– Srinivasan et al. (2010)

  • Workpiece:

Titanium, tW = 0.076 mm

  • Driver:

Copper, tD = 0.381 mm

– Ishibashi et al. (2011)

  • Workpiece:

X5CrNi18-10, tW = 0.15 mm

  • Driver:

EN AW-1050-H24, tD = 0.3 mm

Workpiece thickness Driver thickness Skin depth

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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State of the art

Scientific investigations using driver sheets:

– Tillmann et al. (2008)

  • Workpiece:

DC04, tW = 0,8 mm

  • Driver:

Copper (sputtered), tD = 0,65 mm (optimum)

  • Recommendation:

tD = s

– Bely et al. (1977)

  • Recommendation:

tD = 0,5 s

– Desai et al. (2011)

  • Workpiece:

Stainless steel

  • Driver:

Aluminum, Copper

  • Recommendation:

Aluminum tD = 0,8 s / Copper tD = s Contradicting recommendations No recommendation regarding optimal driver material No consideration of mechanical workpiece parameters – – –

Workpiece thickness Driver thickness Skin depth

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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Introduction Effect of driver sheets State of the art Experimental setup and procedure Results Summary and Outlook

Agenda

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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Free forming of workpiece and driver

Experimental Setup and Procedure

Lower tool

(Flat coil)

Upper tool

(Drawing ring)

tD tW

1

100 mm 80 mm 65 mm 17 mm Coil winding Pulse generator used: Maxwell Magneform 7000

Inner resistance Ri = 4.2 m Inner inductance Li = 60 nH

  • Max. charging energy EC = 20 kJ

Short circuit frequency f* = 25 kHz

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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Free forming of workpiece and driver

Experimental Setup and Procedure

Lower tool

(Flat coil)

Upper tool

(Drawing ring)

tD tW

hW hw = Workpiece forming height tw = Workpiece thickness tD = Driver thickness

Measuring of workpiece height hw

1 2

100 mm 80 mm 65 mm 17 mm Coil winding Pulse generator used: Maxwell Magneform 7000

Inner resistance Ri = 4.2 m Inner inductance Li = 60 nH

  • Max. charging energy EC = 20 kJ

Short circuit frequency f* = 25 kHz

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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Experimental Setup and Procedure

Scope of investigations: – Workpiece material

  • 1.4301, tW = 0.5 / 0.8 / 1.0 mm
  • 1.4509, tW = 0.5 / 0.8 / 1.0 mm
  • DC04, tW = 0.5 / 0.8 / 1.0 mm
  • EN AW-5083, tW = 1.0 mm

– Driver material

  • CU-ETP, tD = 0.3 / 0.5 / 0.7 / 0.8 / 1.0 / 2.0 mm
  • EN AW-1050A, tD = 0.3 / 0.5 / 0.7 / 0.8 / 1.0 / 2.0 mm

– Charging Energy EC

  • EC = 1.0 / 1.8 / 2.4 kJ

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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Introduction Effect of driver sheets State of the art Experimental setup and procedure Results Summary and Outlook

Agenda

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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Results

100 mm 80 mm 65 mm 17 mm

tD tW hW

hw = Workpiece forming height tw = Workpiece thickness tD = Driver thickness

Workpiece: Material 1.4509 Thickness tW = 0.8 mm Forming height hw in mm 12 14 16 18 20 22 24 Driver thickness tD Skin depth S 0.5 1.0 1.5 2.0 2.5 3.0 3.5 12

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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Results

100 mm 80 mm 65 mm 17 mm

tD tW hW

hw = Workpiece forming height tw = Workpiece thickness tD = Driver thickness

Workpiece: Material 1.4509 Thickness tW = 0.8 mm Forming height hw in mm 12 14 16 18 20 22 24 Driver thickness tD Skin depth S 0.5 1.0 1.5 2.0 2.5 3.0 3.5 12 Optimum tD 1.05 S

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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Results

100 mm 80 mm 65 mm 17 mm

tD tW hW

hw = Workpiece forming height tw = Workpiece thickness tD = Driver thickness

Workpiece: Material 1.4509 Thickness tW = 0.8 mm Forming height hw in mm 12 14 16 18 20 22 24 Driver thickness tD Skin depth S 0.5 1.0 1.5 2.0 2.5 3.0 3.5 12 Optimum tD 1.05

EForm Driver Forming Energy EKin Kinetic energy

  • Introduction

Driver Sheets SotA Setup and Procedure Results Summary

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Results

100 mm 80 mm 65 mm 17 mm

tD tW hW

hw = Workpiece forming height tw = Workpiece thickness tD = Driver thickness

Workpiece: Material 1.4509 Thickness tW = 0.8 mm Forming height hw in mm 12 14 16 18 20 22 24 Driver thickness tD Skin depth S 0.5 1.0 1.5 2.0 2.5 3.0 3.5 12 Optimum tD 1.05

EForm Driver Forming Energy EKin Kinetic energy

  • Introduction

Driver Sheets SotA Setup and Procedure Results Summary

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Results

100 mm 80 mm 65 mm 17 mm

tD tW hW

hw = Workpiece forming height tw = Workpiece thickness tD = Driver thickness

Workpiece: Material 1.4509 Thickness tW = 0.8 mm Forming height hw in mm 12 14 16 18 20 22 24 Driver thickness tD Skin depth S 0.5 1.0 1.5 2.0 2.5 3.0 3.5 12 Driver AL CU Charging Energy EC 1.0 kJ 1.8 kJ 2.4 kJ

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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Results

100 mm 80 mm 65 mm 17 mm

tD tW hW

hw = Workpiece forming height tw = Workpiece thickness tD = Driver thickness

Workpiece: Material 1.4301 Thickness tW = 0.8 mm Forming height hw in mm 12 14 16 18 20 22 24 Driver thickness tD Skin depth S 0.5 1.0 1.5 2.0 2.5 3.0 3.5 12 Driver AL CU Charging Energy EC 1.0 kJ 1.8 kJ 2.4 kJ

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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Results

100 mm 80 mm 65 mm 17 mm

tD tW hW

hw = Workpiece forming height tw = Workpiece thickness tD = Driver thickness

Workpiece: Material 1.4301 Thickness tW = 0.8 mm Forming height hw in mm 12 14 16 18 20 22 24 Driver thickness tD Skin depth S 0.5 1.0 1.5 2.0 2.5 3.0 3.5 12 Driver AL CU Charging Energy EC 1.0 kJ 1.8 kJ 2.4 kJ

Aluminium should be favoured as driver material Optimum driver thickness tD,opt 1.1 s – 1.2 s Effect of charging energy EC because of varying strain In case of very small strains (e.g. calibration) copper should be favoured

Conclusions

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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Results

Comparision of optimum driver thicknesses tD,opt

(Driver material: AL)

Conclusions:

Increasing workpiece thickness tW Increasing optimum driver thickness tD,opt Rule of thumb: Optimum driver thickness s (AL)

Workpiece thickness tW Workpiece material 0.5 mm 0.8 mm 1.0 mm 1.4301 0.95s 1.0s 1.27s 1.4509 1.0s 1.05s 1.29s

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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Introduction Effect of driver sheets State of the art Experimental setup and procedure Results Summary and Outlook

Agenda

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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Summary and Outlook

Summary:

– Aluminum should be favoured as driver material – Positive correlation between workpiece thickness tW and

  • ptimum driver thickness tD,opt

– Rule of thumb: Optimum driver thickness s (AL)

Outlook:

– EMF of stainless steel into a conical die using the optimum driver material und thickness – Analytical calculation of the optimum driver thickness tD,opt

Introduction Driver Sheets SotA Setup and Procedure Results Summary

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Questions?