HYDRAULIC force is being employed in an efficient new method of refurbishing large conveyor belts used for materials handling in Queensland coal mines.
Apex Enerka of Mackay has adopted Enerpac hydraulic cylinders to apply the pressure that is needed to vulcanise rubber patches onto the damaged belts that have become torn, holed or split from the wear and tear of conveying coal from the working faces of the mines.
Cylinder pressure is easily, safely and sensitively controlled using a hand-operated Enerpac electric pump.
A typical customer of Apex Enerka is the Oaky Creek North coal mine at Tieri, about 300km inland from Mackay. At any time, Apex is likely to have many 400-metre rolls of conveyor belting from the mine on hand for refurbishing.
"We cut out the damaged pieces of belt and make patches that are vulcanised onto the belt under pressure at 150ºC for 50 minutes or so, depending on the thickness of the conveyor material," said splicing foreman Stuart McMillan.
Heat is applied from beds of cookers above and below the belt being repaired. The beds are pressed against the belt by Enerpac hydraulic cylinders applying force at about 420 bar (6000psi).
Depending on the size of the patching job, small square cookers compressed by a single cylinder are used or - for a repair to a lengthy section of split belt - a long cooker is used with three cylinders that slide independently but act in unison and can press three metres of belt at a time.
"Once the job is in place between the cookers, you turn on the valves controlling the cylinders you want and press the button on the electric pump until the desired pressure is shown on the gauge. A second button releases the pressure," McMillan said.
Apex Enerka had previously employed a spot cooker in a frame that fitted over each of the holes in the conveyor to be repaired. Air pressure was used to secure the frame, but it couldn't achieve the degree of compression of the present equipment.
The RR series of double-acting hydraulic cylinders - with capacities ranging from 10-75 tonnes - are Enerpac's most versatile performers. The RR1012 cylinder adopted by Apex Enerka has a capacity of 10 tonnes, a stroke of 305 mm, an extended height of 762 mm and a collapsed height of 457 mm.
The Enerpac PE series of electric pumps are designed to power most Enerpac hydraulic cylinders and tools. The PER3410E model used by Apex Enerka is a 700 bar pump designed for double-acting cylinders. It is simply controlled by on and off switches mounted on a hand pendant. Applied Power Australia 02 9743 8988.