In order to improve safety at Stora Enso Skoghall in Sweden, the mill’s winder has been rebuilt, which has also resulted in increased production capacity and a better winding process.
The RM 7 winder at Stora Enso Skoghall is a Jagenberg Varidur two-drum winder. The machine was started up 1977 and has a trim width of 5,700 mm.
Automatic set change improves safety
In April 2007, the management at Skoghall decided to rebuild the winder to eliminate manual set changes as part of a major project to improve safety. Switching to automatic set changes has meant considerable changes to the machine. ”We chose to give the order to Metso because our emphasis was on safety and they were able to guarantee a high safety level and good set change time in less than 84 seconds,” says Åke Olsson, a production engineer at the Skoghall KM 7 and project manager for the rebuild.
The fact that the winder was initially made by Jagenberg did not cause any problems, as Metso has a rebuild concept that works well with many types of winders.
Safety improvement in two stages
The safety improvement work was divided into two steps. The first involved rebuilding the control system and modernizing the rider roll system. This was done during the fall of 2007, at which time preparations were also made to install an automatic set change system. Stage two started in early 2008 when the roll pusher, web holder and web cutter with counter blade were replaced. New functions for core gluing and core feeding were installed, as was a new suspension device for end gluing. The set change operation was also changed from manual to fully automatic. The result has significantly improved operator safety, as no manual handling is required during set changes. The rebuild also made it possible to eject smaller rolls than previously, which has eliminated the need to splice an existing roll in the event of a sheet break.
Once the final adjustments and optimization of all sequences had been completed, the rebuilt winder was ready to start up in April 2008.
Positive effects on capacity and winding process
”After a somewhat slow start with a few teething problems in the control system, the machine came right and has now been running very well. However, we did experience some issues after two weeks of production when changing from coated to uncoated grades,” says Åke Olsson. ”Today [early 2009], I can definitely say that all our expectations for the RM 7 rebuild have been more than fulfilled. Winder safety has improved considerably, and we are extremely satisfied with the positive effects of our safety improvement project. Our production capacity has also increased because of the shorter set change time, and we achieved the guaranteed set change time quite easily. Today, set change takes just 80 seconds or so, whereas earlier it took approx. 150 seconds. In fact, the set changes are even quicker for RM 7 than for the much newer RM 8, which was installed in 1996. Further improvement could also be seen once the new hydraulically-controlled rider roll and the new control system were installed – the winding process is now working better and more smoothly than before,” says Åke Olsson.
This is not the first time that Skoghall has rebuilt its RM 7 winder. At the end of the 1980s, automatic end gluing was installed. In 1994, the roll cradle and machine guard, brake generator, and ejector were replaced, and automatic core feeding with manual taping was introduced. In 2000, the converters and DCS system were upgraded and the electrical, hydraulic and pneumatic systems were redesigned and installed. At the same time, Metso installed a new automatic knife section, together with new roll dampers and a new control room.
The tough market situation affecting the paper industry means much tighter investment budgets and fewer resources generally. So rebuilding an existing winder can, in many cases, prove a more cost-effective option than investing in a brand new machine. Rebuilding bit-by-bit will generate a fully modernized winder. In the case of the Skoghall RM 7 winder, the existing frame has been reused and the costly building and concrete work that is normally associated with installing a new winder has been avoided. “This concept is basically a totally new winder, excluding drive system, in an existing frame,” says Åke Olsson.
For more information on improving winder safety at your mill, contact your Metso representative.