Friction Winder Head Rope Life - A Case Study
Abstract
Head rope life on a friction winder reduced significantly over the period of 1988-1997. The winder has four 26mm head ropes and hoists two 12t payload skips from a depth of 1150m.
Rope life reduced from 106,000 cycles for the first three sets of head ropes, to 52,000 cycles for the next three sets. The life reduction coincided with increases in skip mass and payload and the installation of a new PLC and PLC program for controlling the drives. An 'auto levelling' feature was implemented in the PLC to minimise spillage during ore loading.
Axial load range in the ropes is a significant factor affecting winding rope life. Changes to the skip mass and payload and the control system can significantly affect axial load range. Poor load sharing between head ropes also affects load range.
Head and tail rope loads were measured during winding under normal and staged test conditions. Tests were configured to evaluate the effect of different drive controller setups, auto levelling, different payloads and head rope sharing. One controller setup was shown to result in larger rope load ranges than another. The detrimental effect of poor load sharing on rope life was demonstrated.
It was shown that increases in skip mass and payload accounted for part of the reduction in head rope life. The remainder of the reduction was attributed to the effect of the driver controller. A life increase of about 40 per cent should be achieved with the new drive controller setup.