An automatic, laser-based weld seam tracking system is incorporated as standard into all tailor blank welding lines manufactured by Automated Welding Systems (AWS), Ontario. The company, which claims a world lead in 3-axis computer-controlled Nd:YAG laser welding, turned to the Canadian arm of British company, Meta Vision Systems, to provide the 3D tracking equipment.
Tailor-welded blanks are becoming increasingly popular for the production of, for example, doors and chassis assemblies in vehicles. They are also used for component manufacture in the aerospace, electronics and domestic appliance industries. Applicable to steel or aluminium sheet and tube, the technique allows material of different thicknesses to be welded together before being pressed or hydroformed. As the blanks have reinforcement already built in, considerable weight and cost savings result.
AWS also provides services in North America and Europe for short run production of tailor-welded blanks and tubes. However its main business is the manufacture of lines for mass production, which it sells to OEMs and subcontractors worldwide. Early in the development phase, the company recognised that the critical parameter was
controlling the position of the laser welding head in the seam. Once this is correct, all other process parameters fall into place and high quality welds are assured.
In 1995, AWS chose the Quebec branch of Meta Vision Systems to supply laser tracking systems for five welding lines. They proved so successful that AWS decided to equip every line with seam tracking. Fourteen more were installed over the next two years and in 2000 it is estimated that a further 16 systems will be supplied, bringing the total to 35.
Each SeamTracker comprises a LaserVision sensor and a PC-based control. Mounted a short distance ahead of the welding torch, the sensor with its built-in laser diode and CCD camera allows accurate 3D measurement data to be acquired in real time, even under the harshest production conditions. In this application, the sensor has a 5 mm field of view.
The control uses the data to display joint geometry, gap and mismatch to an accuracy of ± 0.02 mm as well as to calculate the optimal lateral and vertical co-ordinates of the torch as it progresses along the seam. Positional corrections are made to the torch 60 times per second to achieve the best possible weld. The system can also be used as a pre-weld validation tool to assess how good the joint will be. If workpiece parameters fall outside preset limits, the line automatically stops.
Welding speeds up to 20 m/min are reported using the tracking system, which has the ability to bridge gaps in non-contiguous blank assemblies.
Different material thicknesses in any combination from 0.5 mm to 3.0 mm are accommodated, sufficient for the majority of tailor blanks used in industry. Gaps from zero to 2.5 mm can be handled. Material types frequently welded are stainless steel, galvanised and cold rolled steel, and aluminium.
Most recently, AWS has begun to offer a post weld inspection option using similar Meta Vision Systems technology.
On behalf of: Meta Vision Systems Ltd, Oakfield House, Oakfield Industrial Estate, Eynsham, Oxfordshire OX8 1TH.
Tel: 01865 887900. Fax: 01865 887901.
E-mail: sales@meta-mvs.com
Contact: Dr Andrew Pryce,
Sales and Marketing Director.
Issued by: THE RIGHT IMAGE,
PO Box 42, Twickenham, TW1 1BQ.
Tel: 020 8891 0603. Fax: 020 8744 1109.
E-mail: tri999pr@aol.com
Contact: Chris Wright.
Release no: 1004(CS)
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