IN-PROCESS VIDEO MONITORING OF ARC STABILITY · PDF fileARC STABILITY AND COMMON WELDING...
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IN-PROCESS VIDEO MONITORING OF ARC STABILITY AND COMMON
WELDING DISCONTINUITIES USING A NOVEL INFRARED IMAGING
TECHNIQUE
David Lammlein, Matt Sinfield, Dennis Lueken, and Michael Pietraszewski
Naval Surface Warfare Center, Carderock [email protected], 301-227-5555
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Problem in Naval Applications
◦ Robotic gas metal arc welding (GMAW) used on critical Naval components requiring full weld length ultrasonic testing (UT)
◦ All indications above threshold UT value must be ground out =>costly
◦ Thus, desired to reduce the total length of bad weld put in
◦ Welder cannot be near weld while robot is in motion (hazardous environment)
◦ Currently defects are found visually or via UT after the weld is complete
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Solution
◦ Detect process instability and discontinuity formation quickly, and then limit indication length by
1) in-process tuning
2) weld abort
◦ Desirable to correlate generation of welding discontinuities (e.g., porosity, lack of fusion, and undercut) with in-process data streams:
1) general process data (current, voltage, wire feed speed, gas flow rate)
2) arc camera video image
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
In-house arc camera solution
◦ Most industrial arc camera technologies based in visible or near wave infrared (IR) spectrum (~0.4-1.4 µm) where radiation energy is high
◦ Arc imaging technique used here based on attenuation of lower energy, long wave infrared (LWIR) radiation (~7–14 µm)
◦ Process shown to be robust in viewing welding arc, weld pool, jointline, and base material for a variety of arc welding processes
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
o Noted features: absence of welding fume, clear image of both arc and weld pool, steady image without flicker, and defined weld pool to base metal interface
o Carderock’s Technology Transition Office looking for potential commercialization partners for the technology
o Sinfield, M.F., Lueken, D.M, and Setlik, B.J., “Longwave Infrared Imaging of a High-Temperature, High-Intensity Light Source,” Navy Case No. 102,787. USPTO Nonprovisional Patent Application, Filing Date: 19 December 2013.
POC: Dr. Joseph Teter, [email protected], 301-227-4299
LWIR Arc Imaging
Pulsed Gas Metal Arc Welding
Shielded Metal Arc Welding Flux-Cored Arc Welding
Below: Images of technique validation for variety of welding types
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
LWIR Arc ImagingLWIR Camera Evaluated 1
Specification FLIR A655sc FLIR Tau 2 FLIR A65 Sofradir Atom
Detector Pitch 17 µm 17 µm 17 µm 17 µm
Detector Material Vox Microbolometer VOx Microbolometer VOx Microbolometer A-Si Microbolometer
Spectral Response 7.5 - 14.0 µm 7.5 - 13.5 µm 7.5 - 13.0 µm 8.0 - 14.0 µm
FPA Format (pixels) 640 x 480 640 x 512 640 x 512 1024 x 768
Dynamic Range 14-bit 14-bit 14-bit 14-bit
Frame Rate (Hz) 50/25/12.5/6.25 30 7.5 30
Connection Type Ethernet Camera Link Ethernet Ethernet
Scene Temp Range -40°C to 150°C -40°C to 160°C -25°C to 135°C Not Available
Weight 0.9 kg ~0.25 kg 0.2 kg < 0.4 kg
Size 216 x 73 x 75 mm 44.5 x 44.5 x 44.5 mm 106 x 40 x 43 mm 61 x 69 x 69 mm
Price (approximate) $20K - $25K $8K - $10K $8K – $10K $20K - $25K
A655sc Tau 2 A65 Atom
1 All images of GMAW-P on steel plate
Imaging technique has been validated on multiple COTS LWIR camera systems
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
LWIR Arc Video Examples
o GMAW-P on steel plate o Single pass fillet weldo Sofradir Atom 1024
o FCAW on steel plate o Mulit-pass, Verticalo FLIR A655sc
Electrode Partial Burn Back Weld Metal Tie-in/Fusion
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Experimental Procedure
Test Condition Voltage (V) Travel Speed (IPM) WFS (IPM)
Nominal 27 11 330
Weave 27 11 330
Joint Offset 27 11 330
Porosity 27 11 330
Undercut 27 12 250
o Five welding conditions were tested
o Single pass fillet welds, spray GMAW
o Arc data was collected at 10 kHz using arc data logger
o Each test weld was remotely monitored using the attenuated LWIR technique (FLIR Tau 2 camera)
o Two welds were made for each test condition to determine optimal viewing orientation:
• Front – camera in front of the weld pool
• Behind – camera behind the weld pool with respect to travel direction
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Equipment Setup
LWIR Camera with Attenuating Filter
Camera Mounting Arm
Robot GMAW Torch
Equipment and Material:
o ABB 4600 Robot
o FLIR Tau 2 LWIR Camera with attenuating filter and 35 mm lens
o Lincoln PowerWave 455m, Operating Mode 5 (Constant Voltage)
o Arc Agent 3000P for arc voltage and current data
o In-house video data acquisition software (LabVIEW based)
o DH36, ¼-in thick steel base plate with ER100S-1, 0.045-in. solid wire
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Mounting Arm
o Noga SuperFlex22”
o 11 lbs capacity at full extension
o 3/8” and ¼” threaded stud connections
o Effectively provides 5 degrees of freedom for camera positioning and orientation
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Nominal Weld – Front View
Welding Direction
o Arc following joint centerline
o Arc stability observable
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Nominal Weld – Back View
arc instability
Welding Direction
o Visible silicates floating in weld pool
o Noticeable arc instability ~20-23 sec into weld
• Observance correlates with arc voltage and current data
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Weave – Front View
Welding Direction
o Arc following joint centerline
o Arc stability observable
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Weave – Back View
Welding Direction
o Visible upper and lower sidewall fusion
o Arc stability observable
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Joint Offset Weld – Front View
Welding Direction
Weld pulling away from side wall
Slight diminish in arc voltage
o 2” of centered weld
o 2” of linearly increasing offset to 0.25”
o 2” of linearly decreasing offset
o Alignment to jointline visible
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Joint Offset Weld – Back View
Welding Direction
Weld pulling away from side wall
Slight diminish in arc voltage
o 2” of center weld
o 2” of linearly increasing offset to 0.25”
o 2” of linearly decreasing offset
o Alignment to jointline visible at extreme offset
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Porosity Weld – Front View
arc instability
Welding Direction
Porosity
o Arc instability between 6-12 sec and 18-25 sec
• Observances correlates with arc voltage and current data
o No porosity visible via front facing camera in weld pool
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Porosity Weld – Back View
Welding Direction
arc instability
Porosity
o Arc instability between 10-13 sec and 18-23 sec
• Observances correlate with arc voltage and current data
o Formation of porosity visible in rear of weld pool during arc instability events
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Undercut Weld – Front View
Welding Direction
Undercuto Undercut in upper fillet is
undetectable in both video and arc data
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Undercut Weld – Back View
Welding Direction
Undercut o Undercut in upper fillet is undetectable in both video and arc data
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Summary◦ Attenuated long wave infrared (LWIR) radiation from the welding
process was used successfully to monitor and detect:
Arc stability and side wall tie-in/fusion
Generation of weld metal porosity
Offset from joint centerline
Wire electrode partial burn back
◦ Attenuated LWIR images are absent of welding fume, exhibit clear image of both arc and weld pool, steady image without flicker, and defined weld pool to base metal interface for a variety of arc welding processes
◦ FLIR Tau 2 with 35 mm lens experiments:
Front View of the weld pool showed arc stability/instability and offset from joint centerline
Back View of the weld pool showed arc stability/instability and formation of weld metal porosity
Unable to detect undercut discontinuities in either camera orientation
◦ Higher resolution LWIR cameras, like the Sofradir Atom 1024 or FLIR A655sc, may be capable of detecting undercut
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Questions
Naval Surface Warfare Center, Carderock [email protected], 301-227-5555
Video of GMAW-P on steel plate with attenuated LWIR using FLIR A655sc
***This work was partially funded by Carderock Division under the Naval Innovative Science and Engineering (NISE) NDAA Section 219 program, managed by the NSWC Carderock Division Director of Research
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