The Nordberg Omnicone gyratory cone crusher is the tertiary crusher in the crushing sequence. It crushes secondary crushed and retained material from a 25mm screen of approximate size 45mm – 25mm through the use of an eccentric rotation. The rotation occurs only at the bottom of the main shaft. A 150KW electric motor creates the drive to the eccentric assembly through multiple drive V belts. The Omnicone is different; however still a gyratory crusher , to the Jaques gyratory cone crusher.
The Omnicone main shaft assembly is not supported at the top its shaft. The main shaft is driven and supported through the eccentric assembly. The eccentric assembly turns at a constant speed, causing the entire main shaft to gyrate. The process is continuous.
Gyratory cone crusher principles
As a tertiary crusher, the Omnicone uses a tertiary mantle and concave which uses a more blunt profile mantle and concave than a secondary crusher mantle and concave wear liner shape profile. The tertiary mantle and concave shape limits the input size of material. As a tertiary crusher it also operates with a CSS of approximately 15 – 18mm. Due to the tighter CSS and the tertiary profile the material thro put, that amount of processed material is lower than the secondary crusher.
The Omnicone has 2 oil systems; a lube system and an adjustment system. The lube system is identical to the Jaques system, oil is transferred from the reservoir by the oil pump. The pump is driven by a speed reducer gearbox which is connected to a 5KW electric motor. Oil then enters a filter, and then through an oil cooler. The oil is forced air cooled, by way of a electric motor driven fan. Oil then enters the crusher through the pinion housing. Oil flows through the pinion housing to the crown wheel and through the eccentric assembly. Oil is then gravity feed through a port in the bottom of the pinion housing and back to the reservoir.
Gyratory cone crusher adjustment system
The adjustment system consists of 2 sub systems. A sub system is called the tramp system. The tramp system holds the clamping ring to the main frame by the use of 4 hydraulic cylinders; they are placed on 90 degree spacing around the crusher body. Oil pressure is maintained in the cylinders to ensure that that top shell of the crushers is held tightly against the mainframe.
The tramp release assembly incorporate an accumulator. There is an accumulator for each hold down cylinder; the accumulator is used as a protection. If a metal object is feed into the crusher oil pressure from the hold down cylinders will flow into the accumulators and release the tramp, this will allow the top shell of the crusher to rise and allow the metal object through the crusher without causing major damage.
Gyratory cone crusher second sub system
The second sub system is for the use of CSS adjustment. As the crusher mantle and concave wear liners wear it must be adjusted to maintain the desired output size rock. To adjust the Omnicone CSS, the tramp system releases the pressure from the hold down cylinders, and by using the directional control valves; oil is directed to the adjusting cylinders. The adjusting cylinders contact the adjusting ring, and lock into the edges. The cylinder continues to extend, pushing the adjusting ring.
The adjusting ring is threaded on the inside and as the adjusting ring turns, so does the concave height with the thread. After the adjustment has occurred, the hold down cylinders regain pressure and clamp the clamping ring to the main frame. The tramping and adjustment oil system draw oil from the same reservoir, through an electric driven oil pump.
CRUSHER PROTECTION SYSTEMS
The crusher is fitted with a similar protection system as the Jaques crusher. The crusher motor is electrically interlocked, therefore the crusher drive motor will not start until the oil pump has been started and the low oil flow sensor is not reading low oil flow. The low oil flow sensor is located on the return side of the lube system, and so oil circulates the entire system and is returned back to the tank, before the low oil flow sensor does not read.
This means that the crusher has sufficient lubrication and can be started. The interlock now allows for the crusher motor to be started. This interlock also works when operating the crusher; if the low oil flow sensor reads low oil flow the crusher motor will stop, as there is a problem.
The Omnicone also has a temperature switch incorporated into its protection system. The temperature switch specifications show that the electric motor can not start until the oil is within the range 16 – 70 degrees Celsius. The temperature switch is also used to switch the electric motor ON and OFF for the cooling fan, it switched the fan ON at 40 degrees Celsius.