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 (%)

Stuttgart University Institute for Metal Forming Technology

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)

Stuttgart University Institute for Metal Forming Technology

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

High Strength Steel Sheets Stretch Drawing of Flat Parts Controllable Draw Beads Cushion Systems and Die Design Summary WagnerS-2005-03 (7)

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)

Stuttgart University Institute for Metal Forming Technology

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)

Stuttgart University Institute for Metal Forming Technology

Source: D. Vlahovic, IFU

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

Stuttgart University Institute for Metal Forming Technology

Source: D. Vlahovic, IFU

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

Stuttgart University Institute for Metal Forming Technology

Source: D. Vlahovic, IFU

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

Stuttgart University Institute for Metal Forming Technology

Source: D. Vlahovic, IFU

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

Stuttgart University Institute for Metal Forming Technology

Principal Strain after Deep Drawing

Principal Strain after Pre-Stretching

Source: D. Vlahovic, IFU

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

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 (15)

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)

Stuttgart University Institute for Metal Forming Technology

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)

Stuttgart University Institute for Metal Forming Technology

Elastic Hinge Vertical Force

Horizontal Force in the Sheet (Restraining Force)

Load Cell Side Wall Stress Sensor Punch Force in the Sheet

Source: S. Beck, IFU

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

Stuttgart University Institute for Metal Forming Technology

Drawbead 3

Connected Optional

Drawbead 2

Drawbead 4

Sensor

Drawbead 1

Source: S. Beck, IFU

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

Stuttgart University Institute for Metal Forming Technology

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)

Stuttgart University Institute for Metal Forming Technology

R

r = 1/R

Source: S. Beck, IFU

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

Stuttgart University Institute for Metal Forming Technology

Source: M. Beth

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

Stuttgart University Institute for Metal Forming Technology

Sidewall of the Part, drawn without Drawbeads

Sidewall of the Part, drawn with Controllable Drawbeads

Source: S. Beck, IFU

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

WagnerS-2005-03 (23)

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 (24)

Stuttgart University Institute for Metal Forming Technology

Box-Profile

C-Profile

Source: M. Häussermann, IFU

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

Stuttgart University Institute for Metal Forming Technology

Blankholder Pressure:

4 ...

... 0 N/mm2

Source: M. Häussermann, IFU

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

Stuttgart University Institute for Metal Forming Technology

Locally increased Blankholder Pressure

Draw Ring

Blank

Blankholder

FPin

F Pin

FPin, increased

F Pin

Source: M. Häussermann, IFU

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

Stuttgart University Institute for Metal Forming Technology

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)

Stuttgart University Institute for Metal Forming Technology

Source: M. Häussermann, IFU

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

Stuttgart University Institute for Metal Forming Technology

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)

Stuttgart University Institute for Metal Forming Technology

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

Source: M. Häussermann, IFU

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

Stuttgart University Institute for Metal Forming Technology

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)

Stuttgart University Institute for Metal Forming Technology

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

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

Stuttgart University Institute for Metal Forming Technology

Experimental Die

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

Stuttgart University Institute for Metal Forming Technology

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)

Stuttgart University Institute for Metal Forming Technology

Source: M. Vulcan, IFU

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

WagnerS-2005-03 (36)

Stuttgart University Institute for Metal Forming Technology

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)

Stuttgart University Institute for Metal Forming Technology

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

Stuttgart University Institute for Metal Forming Technology

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)