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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