weight reduction of heavy duty truck components …/media/files/autosteel/great designs in...

GDIS2017

Weight Reduction of Heavy Duty Truck Components

Through Geometry and Quenching

Gracious Ngaile

North Carolina State University

Department of Mechanical And Aerospace Engineering

#GDIS | #SteelMatters 3

Presentation Outline

1. Introduction and research motivation

2. Research objectives

3. Weight saving through hollow shafts for power transmission

4. Feasibilities of producing hollow shafts for power

transmission

5. Heat treatments and their contribution to weight reduction

6. Concluding remarks


Research Motivation

Weight

Reduction

Advanced Combustion Engines

Aerodynamics Others

Increase Fuel Efficiency

1. Material substitution

2. Part geometry change

3. Heat treatment schemes


Research Motivation

The powertrain for HDV

account for 48% weight

distribution. https://freightliner.com/demand-detroit/

• Currently the power transmission shafts and axles used in most HDV

are solid

• Is it feasible to manufacture hollow shafts in a cost effective manner?


Research Objective

• Investigate the potential of forging lightweight

hollow power transmission shafts for heavy duty

vehicles


Loads Acting on Heavy Duty Truck, Class 8


FEA Study: Potential Weight Reduction of a Gear Box


FEA Study: Potential Weight Reduction of a Gear

Box

• Dead weight at the center of the shaft

• Small increases to OD can eliminate large

amount of material at the center of the shaft

Solid Input Shaft von-Mises Stress

Hollow Input Shaft von-Mises Stress


Hollow Input Shaft Parametric Study Hollow Input Shaft Stress and Mass vs Shape

• The weight saving for using a 38 mm OD

input shaft with wall/diameter ratio of 0.3

is 0.5 kg ~ 13%

• Greater weight savings possible as shaft

diameter is increased

• Greater weight savings if the ID is tailored

for the different areas on the shaft

• Slight modifications to the transmission

case and gears required


Rear Axle FEA Study - Hollow Axle Shaft


Rear Axle FEA Study - Hollow Axle Shaft

Hollow Axle Shaft von-Mises Stress

Solid Axle Shaft von-Mises Stress

• Heavy part (over 21 kg)

• 2-4 axle shafts per truck


Rear Axle Shaft Parametric Study

Hollow Axle Shaft Stress and Mass vs Shape

• The weight saving for using a 47 mm OD axle

shaft with wall/diameter ratio of 0.24 is 5 kg

~24%

• Greater weight savings possible as shaft

diameter is increased

• Minor modifications must be made to the axle

housing and bearings and differential gears

• Forging may provide a practical solution to

creating long hollow parts


Potential Weight Reduction

• Axle shaft weight may be reduced by 5.6 to 7.35 kg (12.3 to 16.2

lbs)

• The input shaft weight may be reduced by 1.75 kg (3.85 lbs)

• The output shaft weight may be reduced by 1.7 to 2.2 kg (3.74 to

4.84 lbs)

• The countershaft weight may be reduced by 0.5 kg (1.1 lbs)

• A truck with a tandem rear axle and three countershafts can

have its weight reduced by a total of about 38.4 kg (86.6 lbs) by

using hollow shaft geometry


Proposed Forging of Axle Shafts from Hollow Tubes

https://www.sypristechnologies.com/products

Conventional forging of

axle shafts

1. Employ existing forging technologies

2. Employ forging machine architecture

3. Employ induction heating technologies

4. Comparable cycle time to forging

Key

Strategies

* Differential Heating Concept*


Proposed Forging of Axle Shafts from Hollow Tubes- FEA

-

Tubular

blank

1st

Induction

heating 2nd

Upsetting 3rd

Flanging

Process

Sequence


Proposed Forging of Axle Shafts from Hollow Tubes - FEA

-

• Optimal differential

heating patterns

• Part strength

characteristics

• Interface friction

• Other

R & D

Tubular

blank

1st

Induction Heating 2nd

Upsetting

3rd

Flanging

Process

Sequence


Proposed Forging of Axle Shafts from Hollow Tubes - FEA

-

• The maximum strain attained is 6.5 mm/mm which is acceptable for hot forging

• Due to oxide, the tube wall will not completely close during upsetting, thus a small

through hole will have to be machined as part of the finishing operations

• Experimental verifications are needed to assess the feasibility of the process

• Induction heating and material flow can be optimized to reduce concentrated strain


Proposed Forging of Pinion Gear Shafts from Hollow Tubes

Proposed Sequence

1. Open die extrusion

2. Induction heating

3. Upsetting to form a solid top part

4. Heading operation


Proposed Forging of Pinion Gear shafts from Hollow Tubes

1st

Open die

extrusion

2nd

Induction

heating

3rd

Upsetting

4th

Heading

Tubular

blank




heating patterns

• Part strength

characteristics


• Cycle time

• Other

R & D

1st

Open Die

extrusion

2nd

Induction

heating

3rd

Upsetting

4th

Heading

Tubular

blank



• The maximum strain attained is 5.3 mm/mm acceptable for hot forging

• Due to oxide formation, the tube will not close during upsetting, thus a small

through hole will have to be machined as part of finishing operations

• Experimental verifications are needed to assess the feasibility of the process


Proposed Forging of Main Shaft from Hollow

Tubes

Proposed Sequence

1. Induction heating

2. Upsetting to form a solid top

3. Flanging operation


Proposed Forging of Main shaft from Hollow Tubes

1st

Induction

heating

2nd

Upsetting 3rd

Flanging


Proposed Forging of Main Shaft from Hollow Tubes

1st Induction Heating

2nd

Upsetting

3rd

Flanging


heating patterns

• Part strength

characteristics


• Cycle time

• Other

R & D


Proposed Forging of Main Shaft from Hollow Tubes

Strain Distribution of

the Main Shaft

• The maximum strain attained is 6.39

mm/mm which is acceptable for hot

forging

• Due to oxide formation, the tube will not

close during upsetting, thus a through

hole will be drilled as part of finishing

operations

• Experimental verifications are needed to

assess the feasibility of the process

• Induction heating and material flow can

be optimized to reduce concentrated

strain


Innovative Heat Treatment Approaches for Weight Reduction - Theory

Residual Stress Induced by Intensive Quenching[7] Rapid vs Slow Cooling Rates[7]

He

at

Tre

atm

en

t P

ara

dig

m [6

]


Innovative Heat Treatment Approaches for Weight Reduction

Removed Mutual System Coupling Full-Float

Axle Shaft

Semi-Float

Axle Shaft

Torsional

Load

Bending Load


Innovative Heat Treatment Approaches for Weight Reduction

Semi-Float Alternating Stresses

• Large Increase in the Residual Compressive Surface Stresses

• Reduction in the Alternating Axial Stresses (Semi-Float Axle)

• Decrease in Required Shaft Diameter (3% Weight Reduction)

• Increased Hardness and Strength in Core

Residual Stresses


Conclusions

• A truck with a tandem rear axle and three countershafts can have its weight

reduced by a total of about 38.4 kg (86.6 lbs) by using hollow shaft geometry

• A forging sequence for hollow shaft based on differential heating of tubular

billet is proposed. The sequence includes three major operations:

i. Heating a section of a tubular stock via induction heating

ii. Upset the heated section into a solid rod

iii. Shape the solid section into a flange or a desired shape by further upsetting

• The proposed forging sequence can be accomplished using conventional tooling

and forging presses/equipment

• Modern heat treating techniques can be employed to improve surface stresses

and reduce component weight


Acknowledgements Students who worked on this project:

James Lowrie, Graduate student

Hao Pang, Graduate student

Aman Akataruzzaman, Graduate student

Joseph Jonkind, Undergraduate student

Steve Henkel, Undergraduate student

Frederic Morrow, Undergraduate student

FIERF and AISI for sponsoring this project

Forging companies and truck manufacturers for providing valuable information for this

project:

Fox Valley Forge, Mid-West Forge, Sona BLW Precision Forge, GKN Sanford, Volvo

Powertrain Manufacturing at Hagerstown MD, and Cleveland Truck Manufacturing

Plant (Freightliner)


References

[1] Transportation Energy Data book, Volume 30:

http://info.ornl.gov/sites/publications/files/Pub31202.pdf

[2] http://www.dieselcrankshaft.com/crankshaft/Vehicle%20crankshaft/2013-05-

13/11173.html

[3] M. Hagedorn, K. Weinert, Manufacturing of composite workpieces with rolling tools,

Journal of Materials Processing Technology, Volumes 153–154, 10 November 2004, Pages

323-329

[4] Brad Fair, Advancement in radial forging, Forge Fair, 2015 Cleveland OH.

[5] Neugebauer, Reimund, Bernd Lorenz, Matthias Kolbe, and Roland Glaß. Hollow drive

shafts-innovation by forming technology. No. 2002-01-1004. SAE Technical Paper, 2002.

[6] Inoue, T. (2002). Metallo-Thermo-Mechanics - Application to Quenching. In G. Totten, M.

Howes, & T. Inoue (Eds.), Handbook of Residual Stress and Deformation of Steel (pp. 296–

311). ASM International.

[7] Intensive Quenching Technology for Advanced Weapon Systems” Phase 1 Report:

Cooperative Agreement Award W15QKN-06-2-0105. December 18, 2007


For More Information

Dr. Gracious Ngaile

North Carolina State University

Department of Mechanical and Aerospace

Engineering

911 Oval Drive, 3160 EB3

Raleigh, NC 27695

[email protected]

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