Meta Vision Systems (Oxford, UK and Montreal, Canada), a supplier of optical seam tracking systems for tube and pipe mills, has released a new version of its VistaWeld system aimed specifically at increasing the speed and accuracy of submerged arc welding (SAW) in longitudinal pipe mills.
The system harnesses the power of Meta's Smart Laser Sensor (SLS) technology. It integrates a high resolution, high performance SLS sensor head within an updated VistaWeld architecture based on an Ethernet backbone and Meta's flexible Ethernet IO board. The combination has made it feasible to include the desired features while reducing system complexity and improving ease of use.
TruRoot tracking finds the actual root of the joint for OD SAW, even though the root may be covered by the tack weld. The software uses the higher resolution and quality of the SLS sensor, together with image analysis algorithms from Meta's multipass welding system, to detect the edges of the tack weld in the bottom of the joint.
From this and the overall joint profile, the true root position can be computed. Tracking the actual root derived in this way improves penetration for the OD weld itself while also improving ID/OD weld interpenetration.
Based on a review of typical longitudinal SAW mill operations involving tack and OD (outside diameter) welding, the system addresses some well-known issues. In particular, the latest VistaWeld includes accurate, non-contact tracking of the true root position and built-in look-ahead compensation as standard features.
The laser sensor has to be positioned a relatively large distance in front of the weld area, the so-called look-ahead distance, which can be 250mm or more.
The standard tracking feature within the new VistaWeld uses the look-ahead distance, welding speed and other information to determine the correct position for the welding head at all points along the pipe. It is particularly beneficial if the pipe forming method has given rise to geometric distortion, as is often the case.
Tests on one series of longitudinal pipes showed that, in some cases, look-ahead tracking was four times more accurate than conventional tracking, significantly enhancing production by improving weld quality and minimising defects.
