Material supplied by Motion Australia
A bespoke hydraulic cylinder, designed and built by CMA for one of the world’s biggest mining equipment manufacturers, is integral to the performance of a unique cutting head.
Three of the new cylinders control the rotational cutting head on a new hard rock mining machine currently in development.
The machine’s design requires the cutting head to move in a manner similar to a hand attached to a wrist, allowing for left, right, upward, downward, forward, and backward movements.
To provide the required level of control there are three of these very substantial cylinders arranged around the outside of the cutting boom. Depending on the operating environment – the type of rock, the width and depth of cut and the like – the cylinders will pivot the cutting head through two rotational axes – up and down and left to right.
Additionally, moving all three cylinders together allows the cutting head to telescope out and back. With the correct degree of control, the new cylinders provide for each of the three movements to be controlled separately giving the machine operators the ability to cut in all directions, improving efficiency and productivity.
The cylinders are a highly engineered combination of hydraulic cylinder and tuned springs with several built-in control functions. Each cylinder includes a load holding valve and a safety valve along with an oil flushing circuit to deliver the functionality, performance, operation, and safety the customer needed for this machine and its operation.
There is also a position sensor fitted inside each cylinder to measure the position of the piston to an accuracy of better than 0.02mm at any one time.
The specifications put the design and manufacturing characteristics and operational strength into black and white. They are rated for over 350 Bar working pressure and weigh in excess of 350kg each.
Retracted length is about 2.5 metres long. The wall thickness is 32mm; the rod diameter is 110mm; overall working stroke is 1 metre; the main barrel is 235mm OD.
They are designed to be exceptionally strong and resist the potential damage underground machinery can suffer. To date, 12 of the cylinders have been built and are now on prototype machines being tested in underground mines in Australia and internationally.
In operation, the cylinders are subjected to a very high frequency vibration which causes the pistons to oscillate through a small distance but at high rate of recurrence.
To overcome the impacts of this vibration the cylinders, as well as controlling the position of the cutting head, are effectively tuned springs, using a carefully calculated volume of hydraulic oil in front of and behind the piston to absorb the vibrations.
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