“The new era of robotic welding will be concentrated in both the manufacturing sector and, to an ever-greater extent, jobbing shops that perform metal fabrication.” – Peter Kuebler, Technical Manager, BOC
Arc robotic welding provides safe, efficient and cost-effective solutions for:
Gas Metal Arc Welding (GMAW) also called MIG and MAG welding
Flux Cored Arc Welding (FCAW)
Submerged Arc Welding (SAW)
Gas Tungsten Arc Welding (GTAW)
All these arc robotic welding systems comprise a robot, welding torch, gun cable assembly, wire feeder, and power and gas sources.
Usually, the welding torch is attached to the robot wrist with an intervening collision sensor or break-away coupling. Internal robot software allows for control over welding arc voltage and wire feed speed. Other signals are transferred from the robot to the power source to turn on the arc shielding system, start the welding process and control manual wire feed forwards and in reverse. Signals are sent from the power source to the robot after the arc is established so that the robot can move along the weld path.
All of the above systems require repeatable placement of the weld joint relative to the filler wire. For quality welding, actual maximum deviation tolerable depends on the process, part thickness, welding position and joint geometry. Where the total deviation is outside the repeatable range, additional systems are used to shift the robot program enabling maintenance of a quality weld. These include:
Touch Sensing: This feature is standard in Kawasaki arc welding software. A low voltage is applied to the welding or filler wire and the robot searches for the edge of a part. When the wire contacts the work, robot software automatically changes the programmed positions to correct the error. Higher detection voltages can be used where the part is not always clean or has mill scale.
Through Arc Sensing (Kawasaki RTPM option): This option is used on thicker workpieces. The system monitors arc length and by weaving the weld wire from side to side in a V joint, modifies the robot programmed position to maintain the arc at the centre of the V.
Laser Tracking: This option uses a laser beam and its reflected signature to detect the arc joint. Search routines can determine the weld start and finish or detect the weld joint position whilst welding.
Torch Cleaning: Gas metal arc welding deposits some spatter into the nozzle. If left unchecked the gas flow is disturbed and the weld quality decreases. On light duty Robot installations, the nozzle can be cleaned manually. Most robot arc welding stations are high duty cycle and require automatic nozzle cleaning stations.
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