Paper mill upgrade turns to Control Techniques drives 18 January 2013

Two lines at SCA's Trafford Park paper mill, which were recently updated with new ac drives from Control Techniques, have seen throughput and accuracy increase alongside operational reliability.

Paul Heywood, who is responsible for keeping the lines working, explains that, to meet production targets, both lines needed new drives. He says the plant has used Control Techniques before, and had good support – hence the choice.

Both lines are now equipped with Unidrive SP ac drives – the tissue line with 26 drives, while the paper towel line has 16, ranging in size from 1.1kW to 20kW.

Functions performed on the tissue line are essentially position control, control of the belt height for the parent roll and tracking, and unwind and rewind control. There is also a section that seals the cut end of the log and the high speed cutting of the log into toilet rolls.

Heywood makes the point that tension control is crucial to prevent web breaks, and says that sheet lengths are controlled to an accuracy of better than 0.5 mm. All the motors have resolver feedback to the drives which convert the data to a compatible scaled feedback for the line's master PLC.

It's a similar story on the paper towel line, with the drives controlling all functions, including unwinding and rewinding, insertion of a new core into the log, the synchro bar, which cuts the log into sections, and log diameter and sheet length control. Again, feedback from the Unimotors is by resolver, scaled in the drive for the PLC.

All of the drives were installed and commissioned by Heywood's engineering team. "We have been helped, when needed, through both upgrades," he says, "and the support generally has been superb."

BrianTinham

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