Meta Turns Laser Tracking Inside Out
Meta Vision Systems has released a new version of its VistaWeld laser tracking system for controlling the position of the internal welding head on spiral pipe mills.
There are two conventional ways of controlling the position of the weld head inside a pipe. In the first method, the laser sensor is mounted directly to the internal head and controls its position by sensing the joint directly ahead of the point of welding. The disadvantage is that there may not be enough space for the sensor inside pipes of small diameter. Another problem in two-step mills is that the internal environment is severe due to the volume of weld spatter.
This led to the development of the second traditional method in which the sensor is mounted outside the pipe on an additional servo slide. The sensor can track the joint dynamically from the outside, as the weld head inside the pipe is mounted on a similar servo slide which mimics the action of the external slide. The disadvantage of this approach is its high cost and complexity, as it requires an expensive additional servo slide system for the sensor only. Moreover, the machine operator has to synchronise both sensor and weld head slides before welding can begin.
Meta's new method has the advantage of placing the sensor on the outside of the pipe but without the disadvantage of a separate sensor slide. The company has developed a new calibration method which, combined with Meta’s high resolution Smart Laser Sensor (SLS), means that the laser sensor can be mounted in a fixed position on the outside of the pipe yet control the position of the weld head accurately inside the pipe. Since the sensor is fixed, there is no need for a separate sensor slide.
The new inside-out VistaWeld SLS tracking system has already been installed on several spiral mills, with good results. It is applicable equally to one-step and two-step mills.
Bob Beattie, Meta’s MD, commented: “Over the past fifteen years, we have supplied many systems for spiral pipe mill ID welding and have acquired a lot of experience in the application.
"Even though we developed some very small laser sensors for going inside, previously there was always a restriction on minimum pipe diameter, whereas with this new approach there is no limitation.
"Accurate laser tracking is now available for ID welding on pipe of any diameter. What’s more, the sensor provides accurate as-welded mismatch measurement that can be monitored by mill operators or used as the input to an automatic mismatch control system.”
Release no: 1044(PR)