According to ARC, the toughest welds to make are full penetration, single sided, V butt, pipe welds. And for the Houston-based developer of welding solutions, it had previously declined these jobs because joint fit-up was never repeatable. "Only human welders with a ‘golden arm’ able to compensate for variation in root openings, weld center lines, and groove volumes could handle this challenge,” said Dan Allford, president of ARC Specialties. "With the industry facing labor shortages, we decided to develop an intelligent machine with complete knowledge of pipe welding, with full motion and welding control."
AIPW incorporates the 6-axis UR5 collaborative robot arm from Universal Robots to carry out the challenging welds. According to ARC, the UR5 is small enough to be portable yet still allows full freedom of motion for both the laser scanner and welding torch.
The AIPW pre-scans the root opening (gap) using a 2D laser, then uses the data to generate the robot path and welding parameters. Gap variations are compensated for with changes in oscillation, torch position, travel speed and welding conditions. The UR5 positions the torch over a tack weld to start the arc to insure 100% root weld acceptance. Fill and cap pass programs are optimized to fill the groove using user selectable weave or stringer bead welding techniques. The AIPW uses the Miller Auto Continuum welding power supply to weld the root with Regulated Metal Deposition (RMD), then switches to pulsed spray for the fill and cap passes. This combination of Gas Metal Arc Welding techniques maximizes welding productivity while producing X-Ray quality, full penetration pipe welds.
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