Since August 1997, automated weld positioning based on non-contact laser seam tracking equipment manufactured by Meta Vision Systems has taken over from manual control of the weld head on no less than 29 tube production lines at the Berlin factory of stainless steel pipe maker, Sosta.

The resulting annual labour cost saving means that the investment in automation is recouped after each retrofit in just over seven months. Moreover, the operators have been released from a particularly tedious job and redeployed elsewhere in the factory.

Payback is in reality even faster, as the above figure does not take into account the reduction in wasted pipe. Scrap inevitably resulted when positioning the weld head manually, as it is difficult for an operator not to lose concentration over long periods. Imperfect products are not an option for Sosta, as its customers within the food, chemical and pharmaceutical industries demand top quality pipework to eliminate the risk of contamination.

The pipe is roll-formed from coil into diameters ranging from 20 mm to 250 mm and TIG welded at about 250 mm/min. The weld head includes a TIG torch with wire feed followed by a second torch to reflow the weld material, giving a smooth finish. This in turn is followed by a polishing head. All welds are 100 per cent ultrasonically tested.

Oxfordshire-based Meta Vision Systems manufactures laser seam tracking equipment which performs everything that a mechanical contact probe is capable of, and at an equivalent price. It can also handle critical situations that a mechanical probe cannot; and is it easier to use.

In tube manufacture, laser sensors score over mechanical devices in a number of ways. For instance the majority of pipe is manufactured from pre-cut sheet and formed along the longitudinal axis. With no further edge preparation the resulting butt joints are very difficult to track mechanically. For tight butt joints, laser tracking becomes the only practical option. Moreover, analysis of the joint profile offers the option of adaptive control to adjust the process parameters during the pipe forming operation.

Even in the most demanding pipe manufacturing applications, such as spiral pipe mills, laser tracking is the preferred method of controlling both internal and external diameter torch positions.

For further information please contact:

Meta Vision Systems Ltd
Attn: Dr Andrew Pryce
Addr: Oakfield House, Oakfield Industrial, Estate, Eynsham, Oxfordshire OX8 1TH.
Phone: 01865 887900
Fax: 01865 887901
Email.