Technological Innovations in Body in White

Technological Innovations in Body in White

BMW
Group
Technological Innovations in Body in
White Manufacturing of the BMW X6
Markus Pfestorf
BMW Group
Duane Copeland
BMW MC
www.autosteel.org
Content
BMW
Group
• Body in White Requirements for EfficientDynamics
• Body in White Materials
• Ultra High Strength Steel Grades
• Joining Technologies
• Conclusion
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Body in White Requirements
Efficient Dynamics
BMW
Group
Body
In
White
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Kin
Pow
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EfficientDynamics
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Body in White Requirements
Cost Efficient Light Weight Design
BMW
Group
Specific Panels
Shared Panels
-
Torsional Stiffness of 29.000Nm/°
Implementation of Ultra High Strength Steel Grades
Mixed Material Concept (Steel, Aluminum, Thermoplastic)
Cost Efficient Engineering using existing Panels with a maximum Design
Differentiation
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Body in White Materials
Yield Strength
BMW
Group
180 MPa
15%
200-220 MPa, 4 %
260 MPa
7%
Deep Drawn Steel
14%
300 MPa
18%
Others, 4%
6xxx Aluminum, 2%
950 MPa, 3%
380-420 MPa, 25%
680 MPa, 5%
550 MPa, 3%
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Body-In-White Materials
Average Minimum Yield Strength
BMW
Group
500
Average min. Yield Strength Rp0,2
475
MPa
400
?
350
Current X5
X6
3´Series Sedan
3´Series Sports W.
300
3´Series Coupé
1´Series
6´Series Convertible
6´Series Coupé
3´Series
5´Series
Sports Wagon 7´Series
3´Series
5´Series
5´Series
Z4´Coupé
Sedan
Z4 Sports Wagon
3´Series
200
Previous X5
Compact
3´Series
7´Series 5´Series
Coupé
3´Series
Sports Wagon
150
Convertible
250
1994
1996
1998
2000
2002
2004
2006
Start of Production
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2008
2010
Body-In-White Materials
Average Thickness
BMW
Group
1,7
mm
3´Series Convertible
1,5
Without Z4
Advanced
High Strength
Steel
6´Series Convertible
Average Thickness
1,4
1,3
Current X5
6´Series Coupé
1,2
3´Series Sports Wagon
Previous X5
7´Series
1,1
5´Series
1,0
0,9
1992
X6
5´Series Sports Wagon
1´Series
7´Series
1994
1996
1998
2000
2002
2004
2006
Start of Production
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2008
2010
BMW
Group
UHSS – Hot Stamped 22MnB5
Side Crash
Thickness (t)
t = 1.2 mm
t = 2.2 mm
t = 1.4 mm
t = 1.2 mm
Weight Savings: 2 kg/side
(compared to a hot stamped part
with a constant thickness)
Mechanical Values:
Yield Strength Rp0,2: > 950 MPa
Tensile Strength Rm: > 1300 MPa
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UHSS – CP800
Rear Crash
BMW
Group
Weight Savings for the
Longitudinal Rear Member:
4,4 kg
(Complete Longitudinal rear member
including other steel grades)
Mechanical Values:
Yield Strength Rp0,2: 680 - 830 MPa
Tensile Strength Rm: 800 - 980 MPa
Elongation A80:
> 10%
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BMW
Group
UHSS – CP800
Rear Crash of a Prototype
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UHSS – CP800
Rear Crash
Yield Strength Rp0,2
Tensile Strength Rm
Elong. after Fracture A80
Thickness
Mech. Properties
(as delivered)
692 MPa
901 MPa
11,4
0,99
Mech. Properties
(180°C, 60 min.)
796 MPa
923 MPa
10,8
0,99
200
Deformation Force
kN
± 118 mm
± 88 mm
BMW
Group
Tested profile
157,37 kN (with Bake Hardening Response)
155,84 kN (without Bake Hardening Response)
120
80
40
Deformation Time
Specimen after Drop Test
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BMW
Group
UHSS – CP800
X6 Part Application
Thickness of all Parts: 1,5 mm
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UHSS – CP800
Tool Realization Guidelines
BMW
Group
d
a
Phase 1
b
Phase 2
Tool Change Content :
a
c
Phase 3
a) Optimize the release of flange form
b) Optimize the draw of the embossments
c) Increase the radii if necessary
d) Optimize the trim
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BMW
Group
UHSS – CP800
Clamping in Body in White
Secure the part fastening assembly process in the Prototype Phase.
• Testing the Series assembly Tools with the Prototype Parts and early
Optimization of the Clamping Technology.
• Higher Measurement Stability in the BIW.
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BMW
Group
Joining Technologies
Materials and Joining Technologies
Main Joining Technologies:
• Resistant Spot Welding (6643 Spot Welds)
• Adhesive Bonding (116999 mm)
Spot Weld
Other Joining Technologies:
• Self Pierce Riveting (82)
• Clinching (53)
• Mig Welding and Brazing (8053 mm)
• Capacitance Discharge Welding
Adhesive Bonding
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BMW
Group
Joining Technologies
Benefit of Structural Adhesives
Applied Adhesives
Local Static Stiffness
Upper Control Arm
+ 12%
Static Torsional Stiffness
+ 2%
Dynamic Stiffness
+ 0.1Hz
to
+ 0.3Hz
Benefit on Stiffness
with Adhesive
without Adhesive
Local Static Transversal Stiffness of
the Upper Control Arm
Difference of Displacements of the
Spring Support with and without Adhesive
Application
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BMW
Group
Joining Technologies
Aluminum Casted Front Shock Tower
Supplier
Body In White
- High Pressure Vaccum
Casting
- Bonding (ca. 5.4 m)
- Heat Treated
Paint Shop
- Self Pierce Rivets (82
times)
- Machined
- Cataphoretic Painting
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- PVC Sealant
Joining Technologies
Capacitance Discharge Welder
BMW
Group
Cold Forged part
Material: C15E2C
Ø 52 mm
Ø 90 mm
Advantages:
- More economical Process
- Less Weld Splatter
- High local connection Stiffness
- Smaller amount of Heat introduced in Parts during
the welding Process
- No Process induced Material Structure Change.
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Joining Technologies
Capacitance Discharge Welder
BMW
Group
2
1
Force (kN)
1,0 mm
Distance (mm)
Force vs. Distance Relationships: Internal Weld Seam Evaluation:
1 Outer projection
2 Inner projection
- Small Fusion Zone
- Small heat induced Zone
- Continuous Material Connection
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200 µm
Conclusion
BMW
Group
• Mixed Material light weight Concept for the Body in White
– 8% Ultra High Strength Steel Grade
– 46% Advanced High Strength Steel Grade
• Significant Weight Savings by UHSS
– Hot Formed B- Pillar Reinforcement with tailor rolled Blank
– CP800 for Longitudinal Rear Member
• Capacitance Discharge Welding for Bushings
– High local stiffness
– Extreme short Process Time
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BMW
Group
Thank You for Your Attention
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