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Advanced Welding Techniques for Tubular Frame Assembly
Menachem KimchiEdison Welding Institute
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WHY TUBULAR FRAME?
• Lighter, stronger, economical, and more rigid structures
• New assembly technologies allow for cheaper and practical space frame designs
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PROJECT HISTORY
• Buckeye Bullet I• Fuel cell• Record speed (322 mph)
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FRAME DESIGN EXAMPLE I
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TECHNOLOGIES FOR FRAME DESIGN I
• Aluminum and steel components• Nodal-type construction
DRW
CSC-GMAW
MPW
“pre-manufactured nodes”
Aluminum Tubes
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FRAME DESIGN II
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FRAME DIMENSIONS
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• Partnered with OSU-Center for Automotive Research (OSU-CAR) for space frame vehicle frame design
• Develop and demonstrate joining processes such as MPW for dissimilar metal joining
• Exhibit DRW capabilities for joining tubular frame structures
• Show some capabilities of CSC-GMAW
• Fabricate a frame for OSU to be used for automotive research
FRAME DESIGN I OVERVIEW
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MAGNETIC PULSE WELDING
• Charging capacitors• Discharging capacitors onto a coil• High transient current in the coil• Inducing secondary current in the part• Generating high electromagnetic force
Charging Circuit
-800
-600
-400
-200
0
200
400
600
800
1000
0 100 200 300 400
Time (microsec)
Cur
rent
(KA
)
induced currentPrimary current
Capacitor Bank
Rogowski Probe
MPW Diagram
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MAGNETIC PULSE WELDING
• Tubular components
• Solid-state welding or mechanical joining
• Dissimilar material joining
• Low heat process
• No distortion
• Non-contact process
• High-speed process (~20 μs)
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• Joined 2.0- and 1.0-in. 6061 aluminum tubing to steel tubing
MAGNETIC PULSE WELDING
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DEFORMATION RESISTANCE WELDING
Reaction Force
Applied ForceCurrent Flow
Expulsed Metal
Folded Tube
Node
Copper Electrode
Collets
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• Effective for thin tubular components• Easily applied to broad range of steel alloys including AHSS• Rapid production rates and easily automated• Process monitoring for quality is applicable• Broad process window for current levels
DEFORMATION RESISTANCE WELDING
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CONTROLLED SHORT CIRCUIT-GMAW
Arc Phase
WD CTW
RFS(1 or 2)
FFS
Short Circuit Phase
User Input Variables
CTW – Contact Tip to Work distance
WD – Withdrawal Distance
Iaa – Arc Phase Start Current
Iab – Arc Phase Pulse Current
Iac – Arc Phase Final Current
taa – Arc Start Time Duration
tab – Arc Pulse Time Duration
Isa – Short Circuit Phase Start Current
Isb – Short Circuit Phase Pulse Current
Isc – Short Circuit Phase Final Current
tsa – Short Circuit Start Time Duration
tsb – Short Circuit Pulse Time Duration
FFS – Forward wire Feed Speed
RFS1 – Reverse wire Feed Speed 1
RFS2 – Reverse wire Feed Speed 2
High Voltage Threshold
Low Voltage Threshold
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• High level of control throughout process• Allows “spatter free” short-circuit transfer modes• Low heat input potential • Capable of very low dilution welds• Effective for precision welding applications
CONTROLLED SHORT CIRCUIT-GMAW
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CONTROLLED SHORT CIRCUIT-GMAW
High-speed video of conventional short-circuit GMAW and CSC-GMAW
Conventional CSC
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• DRW technology enables the design of the space frame using AHSS
• Space frame was designed to meet the planar requirements of the new roof crush specification FMVSS No. 216 for a Hummer H1-Alpha vehicle
• Program includes weld procedure development, weld validation, and the construction and testing of the frame sub-assemblies
FRAME DESIGN II OVERVIEW
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• 20,000-lb max electrode force– Fast follow-up system
• Designed for straight tubular and Planar 2D structures– Large-frame welds – Etc
• Connect to exterior power supply– 400 kVA, 12 V, primary-
rectified DC power
WELD UNIT
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FRAME FOR WELDING
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METALLOGRAPHIC SECTION
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FRAME ASSEMBLY
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• FMVSS 216 simulated load– 23,500-lb force– 5-degree plate angle– 5-in. max displacement
TEST FIXTURE
Fapp
Fapp
Weld
Vertical Stabilizers
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FRAME UNDER TESTING
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• Two frame designs using tubular structures have been demonstrated
• New assembly technologies for the frame constructions have been illustrated.– Magnetic pulse welding (MPW)– Deformation resistance welding (DRW)– Controlled short circuit GMAW
• Frame testing and evaluation methods have been discussed
SUMMARY
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• NASA• Michigan Research Institute• Delphi• SpaceForm, Inc.• Auto/Steel Partnership• Noble• OSU-CAR
ACKNOWLEDGEMENTS
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