Digital laser scanner speeds welding of wind towers

The thickness of the steel plates that form the base of a wind tower can be 50mm or more, while the middle section is fabricated from lighter gauge metal. And near the top, the steel is thinner still. Welding of these various gauges requires different procedures. The base is typically prepared with a U-joint profile and welding takes place in several passes. The middle section requires a V type joint and is welded in one or two passes. Steel at the top is welded with a simple butt joint preparation. The DLS200 sensor has a fully programmable scan configuration, which means that a wide scan can be used for the U and V joints, but a narrow scan with high resolution can be used for the smaller butt joints. Another exclusive feature of the DLS sensor is that the stripe produced by the normal laser scan can be shrunk to a spot. This is useful for welding cap passes where the edges of the weld preparation may have melted away. Wind tower manufacturers say that the main benefit of using the sensor to provide automatic control of the welding process is improved quality. Defects are reduced, which translates into large savings, especially considering the time and cost of repairing root weld defects in thicker material. Bob Beattie, Meta's managing director, said: "We originally developed the DLS300 for multipass welding of very thick walled components such as nuclear vessels. "The new DLS200 sensor has a smaller depth of field with consequently higher resolution. This makes it ideal for the combination of large, medium and small weld joints that are common in wind tower fabrication. "There is no other sensor on the market that is so adaptable and it is generating a lot of interest for other applications, such as making piles for offshore structures and pipe elbow fabrication."