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Great Designs in Steel is Sponsored by:
AK Steel Corporation, ArcelorMittal Dofasco, ArcelorMittal USA,
Nucor Corporation, Severstal North America and United States Steel Corporation
www.autosteel.org
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Logo Here
Lightweight Power Train Components
Chuck Pestow
Dr. Adel Khanfar
Ali Saeedy
U.S. Manufacturing Corporation (USM)
www.autosteel.org
U.S. Manufacturing Corporation (USM)
•
•
•
•
A privately held company with over 45 years experience
ISO/TS 16949 & ISO 14001 certified
Over 800,000 square feet of manufacturing floor
Locations: Warren, MI, U.S. and Silao, Guanajuato,
Mexico
• Customers:
www.autosteel.org
USM’s Products
www.autosteel.org
Industry Needs
The continuing demand for fuel economy
improvements is forcing the automotive
industry to reduce weight
A vehicle manufacturer whose CAFE level for its passenger car or
light truck fleet does not meet the standard for a given model
year is subject to a civil penalty of $5.50 per tenth of a mpg
if the manufacturer’s CAFE level is below the required CAFE
level multiplied by the number of vehicles
www.autosteel.org
Ford’s Industry Plan
www.autosteel.org
Chrysler’s Industry Plan
“Chrysler’s goal is to improve fuel economy by reducing weight
and making its vehicles more aerodynamic” said Chrysler Engineering Chief,
Scott Kunselman
www.autosteel.org
Other Automotive Manufacturers
→ Nissan
Nissan Motor Co. is targeting an average 15% reduction in the weight of its
vehicles by 2015, compared to the 2005 lineup, to reduce fuel consumption by
10%.
→ Mazda
Mazda Motor Corp. will reduce its vehicle weights by at least 220 pounds
beginning in 2011, with a combination of lighter-weight materials, smaller
vehicle footprints and new engineering processes,
said Robert Davis, Senior Vice President of Product Development and Quality for Mazda North American
Operations
→ Hyundai-Kia
“In addition to more efficient drivetrains, Hyundai will use aluminum, plastic
and high strength steel to reduce the weight of its vehicles”
said Lee Hyun-soon, Hyundai-Kia Automotive Group's R&D
→ GM
“(Volt is) heavier than I would like. Efforts are being made to reduce weight of
both the car and 400 pound battery pack”.
said Andrew Farah, Vehicle Chief Engineer
www.autosteel.org
USM’s Contributions
Provide the engineering design expertise and
manufacturing technology to make significant weightsavings possible by:
9 Replacing constant-wall axle tube housings with
variable-wall axle tubes (VARI-LITE®)
9 Replacing solid shafts with hollow shafts
www.autosteel.org
USM’s Variable-Wall Axle Tubes (VARI-LITE®)
Near Net Shape
Spindle
Thin Wall as
Needed
Thick Wall Near Axle
Housing Interface
Conventional Tube with Straight Wall Thickness: 64.5 lb
USM Lightweight Tube with Variable Wall Thickness: 51.8 lb
A mass reduction of 25.4 lbs (or 20 %) per rear
axle assembly or vehicle
www.autosteel.org
USM
VARI-LITE ®
Designs
Traditional
Designs
Adel Khanfar
U.S. Manufacturing Corporation (USM)
www.autosteel.org
Vehicle Energy Demand*
5%
2%1%
Mass
6%
Mass
Inertia
35%
9%
Tire Rolling & Brakes
Aerodynamics
Torque Converter
Axles
10%
Transmission
Alternator
Fan
7%
10%
Transfer Case
15%
*Will vary for different vehicle classes, driving behaviors/cycles and power trains
www.autosteel.org
Hybrid Electric Vehicles
Weight is an essential factor in the fuel consumption
formula of all vehicles including hybrid electric vehicles
due to the significant mass of the battery
Conventional Internal
Combustion Engine
Battery
Example: Chevy Volt
Courtesy of GM; http://www.chevy-volt.net
www.autosteel.org
Vehicle Fuel Economy Sensitivity to Mass
Pvehicle = f (Pbattery, Pfuel, ηp/train, ηfuel converter)
Power required to
operate the
vehicle
Power extracted
from the battery
P: Power
Power extracted
from the fuel
η: Efficiency
Efficiency of the
power train
m: Mass
www.autosteel.org
Efficiency of the
fuel converter
Vehicle Fuel Economy Sensitivity to Mass
Pvehicle = (Pbattery x ηp/train) + (Pfuel x ηfuel converter x ηp/train)
d
dm
Pvehicle
d
=
dm
Pbattery x ηp/train
+
d Pfuel x ηfuel converter x ηp/train
dm
=
Pbattery x dηp/train
dm
+
ηp/train x dPbattery
dm
Pfuel x ηfuel converter x dηp/train
+
+
Pfuel x ηp/train x dηfuel converter
dm
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dm
Vehicle Fuel Economy Sensitivity to Mass
1
ηfuel converter.ηp/train
dPvehicle
dm
=
Pfuel
ηp/train
dηp/train
dm
Pfuel
+
ηfuel converter
Pbattery
dηp/train
ηfuel converter. ηp/train
dm
E=
+
P(t)dt
www.autosteel.org
dηfuel converter
dm
+
1
dPbattery
ηfuel converter
dm
Vehicle Fuel Economy Sensitivity to Mass
dEfuel
dm
=
-
-
-
1
dPvehicle
dm
ηfuel conv.ηp/train
Pfuel
dηp/train
ηp/train
dm
Pbattery
ηfuel conv.ηp/train
Pfuel
dt dηp/train
dt
ηfuel conv
dt
dm
1
dPbattery
ηfuel conv
dm
dt
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dηfuel conv
dm
dt
Vehicle Fuel Economy Sensitivity to Mass
Lightweight Vehicle = Fuel Efficient Vehicle
10 % vehicle weight reduction can reduce vehicle fuel consumption by up to
8.2 % depending on the size and type of vehicle
Reduction in Fuel Consumption (%) as a result of 10% Vehicle Weight Reduction (Mid-Size Class)*
* Reproduced graph; Source: Determination of Weight Elasticity of Fuel Economy for Conventional ICE Vehicles, Hybrid vehicles, and Fuel Cell vehicles, Forschungsgesellschaft
Kraftfahrwesen mbH, Aachen, project 55510, 2007; International Iron and Steel Institute http://www.worldautosteel.org/uploaded/FkaReportWeightElasticityStudy062107FINAL.pdf
www.autosteel.org
18
USM’s Hollow Shaft Technology
How does USM do it? Its proprietary and patented cold
forming technologies and heat treatment processes
1. Optimized Cross Section Tubular Design
Thicker Walls for Highly Stressed Areas and Welded Zones
Reduced Wall Thickness for Non/Low Stressed Areas
Optimum Tuning for Stiffness & Strength
Optimum Geometry to Maximize Mass Savings
Reduced Wall Thickness in Non/Low-Stressed Areas
to Minimize Mass & Optimize Stiffness
Thick Wall in Highly Stressed Areas
e.g. Near Spline
www.autosteel.org
USM’s Hollow Shaft Technology
2. Advanced Metal Forming Process
- Simulation
3. Advanced Post Processing As Required
- Heat treatment, coatings, etc.
www.autosteel.org
USM’s Hollow Shaft Technology
What are the advantages of USM’s proprietary process?
• Short process cycle times
• Flexible process & low cost tool changes
• Tight tolerances & excellent surface quality
• Near net shape forming
• Save material
• Save weight
• Increase in the tensile strength of the material by up to 825 MPa = 120 ksi
depending on the work hardening properties of the material
• May allow the use of less costly materials with lower initial tensile strength
www.autosteel.org
USM’s Hollow Shaft Technology
Strength & Weight of a Hollow Shaft
(Compared to a Solid Shaft with the Same OD)
20%
15%
Reduction in Weight
Reduction in Torque Capacity
10%
5%
0%
0%
10%
20%
30%
40%
50%
60%
ID/OD
A 16% reduction in weight results in only a 2.5% reduction in torque capacity
www.autosteel.org
Hollow Shaft Advantage
A hollow shaft is much more
STRUCTURALLY EFFICIENT
than a solid shaft…
Strength
Weight
>
Hollow
Strength
Weight
Solid
www.autosteel.org
How do we design & develop a hollow shaft?
9 Ensure functional performance: Transmission of torque under
customer-specified operating conditions and duty cycles
9 Through design, material selection, and heat treat optimization,
hollow shafts have equivalent allowable limiting load values as
solid shafts
9 Enhanced NVH performance: natural frequencies of bending
oscillations, torsional deflection, damping characteristics, and
rigidity
How is this accomplished? Through the optimal distribution of
mass
www.autosteel.org
Great Designs in Steel
Case Study
Ali Saeedy
U.S. Manufacturing Corporation (USM)
www.autosteel.org
We reduced the mass of this
light truck rear axle shaft by
8 lbs / vehicle
(or 23%)
www.autosteel.org
Case 1: Lightweight Hollow Rear Axle Shafts for Light Trucks
Original Solid Axle Shaft
Hollow Structure
USM’s hollow axle shaft is approx. 4.0 lb or 23 % lighter than the
conventional solid shaft
www.autosteel.org
27
Lightweight Hollow Rear Axle Shafts for Light Trucks
• Variable Wall Thickness
• 2 pc welded construction
Variable Wall Formed Tube
Forged Flange
Thin Wall for Non Stressed Area to
Reduce Weight & Optimize Stiffness
Thick Wall at the Weld Zone
Thick Wall Adjacent to Spline
www.autosteel.org
Lightweight Hollow Rear Axle Shafts for Light Trucks
Item
Part Geometry
Solid
Hollow Shaft
VARI-LITE ®
Change
% of
Change
Effective length (mm)
938.3
938.3
0
0
Nominal OD (mm)
(Main body)
34.3/38.1
35.6/38.1/38.1
N/A
N/A
Nominal wall thickness (mm)
Solid
6.25-11.5
N/A
N/A
Shaft Diameter Tolerance (mm)
±0.5
± 0.15
- 0.35
- 70%
Maximum Shaft Runout (mm)
3.0
1.5
- 1.5
- 50%
8.2
6.3
1.9
- 23%
Mass per shaft, (kg)
www.autosteel.org
29
Lightweight Hollow Rear Axle Shaft - Stiffness Comparison
Fixed Support
Fixed Support
Load=1000 lbf
Load=1000 lbf
Hollow Shaft
Solid Shaft
Stiffness
Solid Shaft
Hollow Shaft
% Change
Torsional (Calculated)
212 N.m/deg
253 N.m/deg
+19%
Bending (FEA)
48.5 KN/m
61.4 KN/m
+26%
The hollow shaft has higher torsional & bending stiffness’ when compared to the solid shaft
www.autosteel.org
30
Lightweight Hollow Rear Axle Shaft – NVH Performance
Natural Frequency
(Hz)
Mode
Solid Shaft
Hollow Shaft
% Change
1st
27.6
35.5
+28.6%
2nd
27.6
35.5
+28.6%
3rd
172.6
221.1
+28.1%
The hollow shaft design has enhanced NVH performance when compared to the solid shaft
Fixed Support
Solid Shaft
Fixed Support
Hollow Shaft
www.autosteel.org
31
Lightweight Hollow Rear Axle Shaft - Torsional Fatigue Performance
T2
Torque
Requirement/Bogey
Per Customer Specs
Hollow Shaft
T1
10,000
100,000
1,000,000
Number of Cycles
The torsional fatigue performance of the USM-designed
hollow shaft EXCEEDS customer fatigue life requirements
www.autosteel.org
32
Lightweight Hollow Rear Axle Shaft – Ultimate Torsion Strength
Torque vs. Angle
Torque, N.m
14000
Hollow Shaft
Solid Shaft
12000
10000
8000
6000
4000
2000
0
0
50
100
150
200
250
300
350
400
Angle, Degree
The Ultimate Torsion Strength of the USM-designed hollow
shaft EXCEEDS the UTS of a Solid Shaft
www.autosteel.org
Case 2: Lightweight Hollow Front Drive Shafts for Passenger Cars
The inboard end of the
intermediate drive shaft
assembly interfaces with
the differential transmission
Transmission
Front Half Shaft
Intermediate Drive Shaft Assembly
www.autosteel.org
The outboard end of the
intermediate drive shaft
assembly interfaces with
the front half shaft
Lightweight Hollow Front Drive Shafts for Passenger Cars
Lightweight Hollow Intermediate Drive Shaft (Assembly)
Reduced Mass: Approx. 30%
Optimum Tuning for Torsional Stiffness and Natural Frequency
www.autosteel.org
Lightweight Hollow Intermediate Drive Shafts
Application:
Passenger Cars, North America
Manufacturing Location:
Warren, Michigan
Start of production:
2011
Annual Volume:
Approx. 800,000 assemblies
Male-Female Spline Interfaces
Male-Male Spline Interfaces
www.autosteel.org
36
Lightweight Hollow Intermediate Drive Shafts
Tubular Blank
Form to Near Net Shape
Final Product
www.autosteel.org
Lightweight Hollow Intermediate Drive Shafts
USM is 100% Design, Manufacturing, and Assembly Responsible
Initial Hollow Shaft
Tech Review
4/22/09
Received LOI
for Production & Prototype
6/3/09
Received RFQ
from Customer
4/9/09
Concept Layout
Initial Design
Validation Complete
10/1/09
Production PO
Received
8/10/09
Design
Analysis, Simulation & Prediction
Prototype Parts
Delivered
12/4/09
Sample Parts
Shipped
10/15/09
Development Testing
www.autosteel.org
Integration
Production
USM’s Technology Capabilities
A Variety of Tubular Configurations
Size Capabilities
Multiple Outside Diameters
Variable Wall Thicknesses
Combination of Both
Outside Diameters 1” – 8”
OD & ID Tolerances as low as +/-0.002”
Lengths from 4” to 80”
Multiple Outside Diameters
Variable Wall Thickness
Variable Wall Thickness
and Multiple Outside Diameters
www.autosteel.org
USM’s
Many Potential
Technology
Applications
Capabilities
Hollow Intermediate
Drive Shafts
CVJ / Drive Shafts
Hollow Axle Shafts
Starters
Hollow Transmission
Shafts
Hollow Half Shafts
Hollow Steering Rack; Low Inertia
www.autosteel.org
40
Final Comments
9 In order to achieve an overall reduction in vehicle fuel
consumption, advanced technologies that offer improved fuel
efficiency opportunities are required.
9 The size and weight of vehicles are essential factors in the fuel
consumption formula, and weight savings will remain a
continuing requirement to enable fuel economy gains.
9 USM’s proprietary cold forming and heat treat processes are
ideal for satisfying the design requirements of modern
automotive components.
9 Replacing conventional solid shafts with USM’s hollow shaft
designs across a wide range of vehicle applications can reduce
component mass by up to 40%.
www.autosteel.org
41
Questions
Chuck Pestow
Dr. Adel Khanfar
Ali Saeedy
V.P. Sales, Marketing
& Product Development
[email protected]
586-467-1539
Manager of Product
Development
[email protected]
586-467-1584
Sr. Product Engineer
U.S. Manufacturing Corporation
www.usmfg.com
28201 Van Dyke,
Warren, MI 48093, USA
www.autosteel.org
[email protected]
586-467-1588
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, ArcelorMittal Dofasco, ArcelorMittal USA,
Nucor Corporation, Severstal North America and United States Steel Corporation
www.autosteel.org