Finnish paper web edge-tracking system offers major advantages to paper makers

Citation

(2002), "Finnish paper web edge-tracking system offers major advantages to paper makers", Sensor Review, Vol. 22 No. 4. https://doi.org/10.1108/sr.2002.08722daf.004

Finnish paper web edge-tracking system offers major advantages to paper makers

Finnish paper web edge-tracking system offers major advantages to paper makers

Keyword: Machine vision

Successful installations of the VISIEDGE edge-tracking system developed by Vision Systems Oy of Jyväskyä, Finland show that it accurately and continuously tracks the web edge on winders and supercalenders, as well as on paper machines producing board or very high-speed machines producing LWC, SC and newsprint grades. Typical payback time for VISIEDGE is only a few months (see Plate 4).

The system, based on high-speed CCD line-scan camera technology, comprises an integrated measurement and illumination unit in an air-cooled housing, advanced userinterface software and a box for the electronics and power supply. VISIEDGE can be used with both reflected and back light and, using two measurement heads, the measurement area at both edges of the web is 250mm. The system operates in real time and provides 100 per cent coverage of paper web edge-positions and the width of the paper web.

Plate 4 The VISIEDGE edge-tracking system

Benefits at the paper machine and supercalender

VISIEDGE produces significant benefits for paper makers by providing accurate, comprehensive measurement data, regarding paper web edge-positions and web width at the dry end of paper machines, which are used for CD control of the dilution head box.

VISIEDGE has also been exploited at the supercalender, where it implements automatic and non-contact paper web guidance during oscillation of a paper web. As a result, supercalender operators can concentrate on more profitable tasks.

Successful exploitation of winder applications

Another recent application of VISIEDGE is to minimise edge trimming of a supercalendered paper roll. Under normal conditions, the web is oscillated continuously at the supercalender by 50mm, for example, from left to right and back in order to avoid uneven wear on the rolls in the calender's roll stack. This oscillation needs to be brought back to normal at the winder in order to minimise trimmed strip.

A new approach to edge-mark tracking and web edge control

A new use for VISIEDGE has resulted from co-operation between ABB and Vision Systems Oy whereby VISIEDGE is integrated with ABB's active braking system (ABS) for winders. ABB supplies ULMA NTi Web Inspection Systems at the dry end of paper machines to detect and classify defects in the paper web by using a colour marker to denote the position and type of defect on the web edge.

When the colour-marked parent roll moves to the winder for slitting or rewinding, the colour marks on the web edge need to be tracked while the parent roll is opened on a winder reel. VISIEDGE is used with ABB's ABS system to track the colour marks on the web edges at full processing speed to provide the down-web locations of the defects. VISIEDGE also simultaneously measures and controls the paper web edges at the winder.

Optional web-reeling control feature

As an extended and more comprehensive delivery VISIEDGE can also be supplied with a web-reeling control feature; its intelligent line-scan camera system controls paper web reeling, without any PLC-control, to provide non-contact web edge position measurement and control and to allow paper web oscillation during reeling.

Further information from: Vision Systems Oy, P.O. Box 353, Jyväskylä, Finland. Tel. +358 14 617 722; Fax: +358 14 617 844; E-mail: kari.rahkola@visionsys.fi; Web site: www.visionsys.fi