13 - Tool and Die Design for Deeping Drawing AHSS

Institute for Metal Forming Technology Prof. Dr.-Ing. Dr. h.c. Klaus Siegert

Tool and Die Design for Deep Drawing AHSS

Prof. Dr.-Ing. Dr. h.c. Klaus Siegert Dipl.-Ing. M. Vulcan

Stuttgart University Institute for Metal Forming Technology

High Strength Steel Sheets Stretch Drawing of Flat Parts Controllable Draw Beads Cushion Systems and Die Design Summary WagnerS-2005-03 (2)

Stuttgart University Institute for Metal Forming Technology Multiphase Steel

Isotropic Steel Higher-Strength IF-Steel

Dual Phase Steel

Solid solution hardening by adding phosphorus Hardening by carbides of micro alloy elements Ti, Nb, V

Micro-Alloyed Steel 1985

Solid solution hardening

Embedding hard martensite parts in ferritic matrix

Phosphorus-Alloyed Steel

1980

Concerted control of grain refining by adding Titanium

Diffusion of interst. N und C to increase the yield strength

Bake Hardening Steel

1975

Increase of strength by microstructural change

1990

1995

2000

Source: Thyssen

Development of High Strength Steels WagnerS-2005-03 (3)

Elongation at Fracture A80 (%)


60 50

Bake Hardening Steel HSLA 180BH HSLA 300BH

IF- Steel IF 180 IF 260

Phosphor alloyed HSLA 220P HSLA 300P

TRIP - Steel TRIP 700 TRIP 800

40

Dual-Phase Steel DP 500 DP 600

30 20 10

Isotropic HSLA 220i HSLA 280i

0 200

300

Complex-Phase Steel CP-W 800 CP-W 1000

Micro Alloyed HSLA 260 HSLA 420 400

500

600

700

800

900

1000

MartensiteSteel MS-W 1000 MS-W 1200

1100

Tensile Strength Rm (MPa)

Comparison of Different Steel Grades WagnerS-2005-03 (4)

Stuttgart University Institute for Metal Forming Technology 900

kf

TRIP 700

[N/mm²] DP 600

700

DP 500 600 500 IF 260 400

FePO4

300 200 100 0

0,05

0,10

0,15 Logarithmic True Strain

ϕg

Source: IFU

Flow Curves of Actual Sheet Metals WagnerS-2005-03 (5)


Yield Strength in MPa min

UTS in MPa

max

min

max

Elong. at Fracture A80 in %

R-Value 0°

45°

90°

High Strength Bake-Hardening Steels HSLA 180 BH

180

240

300

380

32

rm = 1,9

HSLA 220 BH

220

280

320

400

30

rm = 1,5

HSLA 260 BH

260

320

360

440

28

rm = 1,4

HSLA 300 BH

300

360

400

480

26

rm = 1,3

High and Advanced High Strength Steels DP 600

381

574

23

DP 700

583

735

16

DP 800

567

869

10

TRIP 700

680

850

20-30

CP 800

793

903

14

MS 1200

1150

1350

6

0,9

0,8

0,7

Source: Birzer WagnerS-2005-03 (6)



Stuttgart University Institute for Metal Forming Technology Punch

Hydraulic Valves

Gripper

Frame Blankholder

Source: T. Krockenberger, IFU

Test Equipment for Stretch Drawing followed by Deep Drawing WagnerS-2005-03 (8)


Source: T. Krockenberger, IFU

Test Equipment for Stretch Drawing followed by Deep Drawing, Installed in Single Acting Hydraulic Press at IFU

WagnerS-2005-03 (9)


Source: D. Vlahovic, IFU

First Stage: Clamping the Sheet WagnerS-2005-03 (10)



Second Stage: Predefined Stretching of the Sheet WagnerS-2005-03 (11)



Third Stage: Tool Closing WagnerS-2005-03 (12)



Last Stage: Deep Drawing of the Sun Roof Panel WagnerS-2005-03 (13)


Principal Strain after Deep Drawing

Principal Strain after Pre-Stretching


Results FEM Process Simulation WagnerS-2005-03 (14)



Stuttgart University Institute for Metal Forming Technology Springback Reduction:

Guideline:

Increased Wall Stresses in the Straight Sides by Driving the Active Drawbeads Upwards.

σWall< 0,8 σFracture Safety Factor

σFracture Safety Distance

σz, Wall, Drawbead σz, Wall, Basic

Source: S. Beck, IFU

Desired Wall Stress Distribution WagnerS-2005-03 (16)


Safety Distance

Additional Force by Increased Blankholder Force and/or Increased Drawbead Height

Intention: Improved Wall Quality by Introducing Additional Forces Source: S. Beck, IFU

Desired Punch Force Trajectory WagnerS-2005-03 (17)


Elastic Hinge Vertical Force

Horizontal Force in the Sheet (Restraining Force)

Load Cell Side Wall Stress Sensor Punch Force in the Sheet


Side Wall Stress Sensor WagnerS-2005-03 (18)


Drawbead 3

Connected Optional

Drawbead 2

Drawbead 4

Sensor

Drawbead 1


Position of the Wall Stress Sensors and Position of the Drawbeads WagnerS-2005-03 (19)


350 Stress at Fracture

Stress in N/mm

2

300 250 200 150 100

Stress 1 Stress 2 Stress 3 Stress 4

50 0 0

20

40

60

80

100

120

Stroke in mm Quelle: S. Beck, IFU

Side Wall Stress vs. Stroke for Constant Draw Bead Heights WagnerS-2005-03 (20)


R

r = 1/R


Curvature of the Side Wall for Variable Draw Bead Heights vs. Stroke WagnerS-2005-03 (21)


Source: M. Beth

Springback Phenomena when Drawing U-Profiles WagnerS-2005-03 (22)


Sidewall of the Part, drawn without Drawbeads

Sidewall of the Part, drawn with Controllable Drawbeads


Surface Quality with and without Controllable Drawbeads (Measured with the System Diffracto)

WagnerS-2005-03 (23)




Box-Profile

C-Profile

Source: M. Häussermann, IFU

Design of Conventional Draw Dies WagnerS-2005-03 (25)


Blankholder Pressure:

4 ...

... 0 N/mm2


Blankholder Pressure by the Box-Profile WagnerS-2005-03 (26)


Locally increased Blankholder Pressure

Draw Ring

Blank

Blankholder

FPin

F Pin

FPin, increased

F Pin


Principle of the Segment-Elastic Blankholder WagnerS-2005-03 (27)


Draw Die with Segment-Elastic Blankholder, Prismatic Designed Draw Ring and 10-Point Cushion System Integrated into the Die

Prismatc Designed Draw Ring

Punch Segment-Eelastic Blankholder Guide Return Stroke Cylinders Stroke Measurement

Servo Valves

Bottom Plate Hydraulic Cylinders Source: M. Häussermann, IFU WagnerS-2005-03 (28)



Hydraulic Multipoint Cushion System in the Die WagnerS-2005-03 (29)


Normal Pressure:

Equal Pin Forces

4,5 ...

... 0 N/mm2

Increase of 100% in the Middle Area

Source: M. Häussermann, IFU WagnerS-2005-03 (30)


Total Blankholder Force 530kN

7 kN

102 kN

99 kN

13 kN

24 kN

43 kN

2 kN

Good Part with 68 mm Draw Depth

90 kN

98 kN

52 kN


Optimization of the Cushion Pin Forces WagnerS-2005-03 (31)


Die for the Deep Drawing of Longitudinal Beams with Cushion System integrated into the Die

Punch

Blankholder

Valves 18 Nytrogen Cylinders

Cables and sensors Source: D. Haller, IFU WagnerS-2005-03 (32)


Die for the Deep Drawing of Longitudinal Beams with Cushion System integrated into the Die

Source: D. Haller, IFU WagnerS-2005-03 (33)


Experimental Die

Source: J. Hengelhaupt, IFU WagnerS-2005-03 (34)


Hydraulic HMI

Main Mobile Hydraulic Unit

MOOG Controller Units Source: IFU

HYDAC Power Unit

Press HMI

Cooling System

10 Point Flexible Binder Die

20.000 kN Hydraulic Press at the IFU

2 x Return Tank Units

IFU HMI

2 x Bladder Accumulators Station (each 1 x 60 bar and 2 x 10 bar) WagnerS-2005-03 (35)


Source: M. Vulcan, IFU

Control system with Touch Screen to Adjust the Blankholder Pressure Area by Area

WagnerS-2005-03 (36)


Nominal Value

Friction Force versus the Stroke Max. Wrinkle Height

Stroke

Actual Values Controller Ram Upper Binder Segment-elastic Blankholder Measuring Friction Force and Wrinkle Height

Cushion System integrated into the Die

Source: IFU

Design of Closed Loop Control of the BHF WagnerS-2005-03 (37)


Tool and Die Design for Deep Drawing AHSS

WagnerS-2005-03 (38)

w w w . a u t o s t e e l . o r g


Great Designs in Steel is Sponsored by: •AK Steel Corporation •Dofasco Inc.

•Mittal Steel Company •Nucor Corporation

•Severstal North America Inc. •United States Steel Corporation WagnerS-2005-03 (39)

13 - Tool and Die Design for Deeping Drawing AHSS

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