09/27/2011 | Editor: Marcel Dröttboom
New newly developed coupling for open-pit mining belt conveyors has been specially designed for induction motors operating at speeds of 900 to 1200 rpm. The new fluid coupling transmits twice the power previous couplings of the same size could achieve.
Crailsheim, Germany – Open-pit mining belt conveyors often transport the extracted raw materials over long distances. Voith Turbo has developed a new coupling, the "TurboBelt 780 TPXL", for the drives of these belt conveyors. It has been specially designed for induction motors operating at speeds of 900 to 1200 rpm. According to Voith Turbo, this new fluid coupling transmits twice the power previous couplings of the same size could achieve. The controlled start-up with precisely-dosed introduction of torque is especially easy on the belt, but also on the entire driveline. Start-up times of up to several minutes can be individually set in the control system.
At the heart of the new development is the profile of the blade wheels in the coupling. Voith's fluid engineers have optimized this profile using modern numerical techniques of flow simulation (computational fluid dynamics - CFD). The blade wheels transmit double the power with the same diameter. To be precise, the new fluid coupling transfers 1100 kilowatts at 900 rpm, 1500 kilowatts at 1000 rpm and 1900 kilowatts at 1200 rpm. Power transmission is wear-free, as with all hydrodynamic couplings.
Power density is further increased thanks to the direct attachment of the coupling to the motor flange, combined with two flow circuits operating in parallel. Voith Turbo says, that compared with traditional couplings, this system would require only half as much installation space and would also also be significantly lighter. Installation and alignment would be both simple and quick. Overall, the entire drive is lighter and more compact. This can be beneficial when moving the conveyor system, for example.
The optimized, hydrodynamic power transmission with the TurboBelt offers many advantages to operators of belt conveyors: The very precise control of torque transmission protects the belt, as well as extending its service life. Longitudinal dynamic tension waves in the belt can be effectively avoided. The drive motors run under less strain, so oversizing them is not necessary. Even overloaded belt conveyors can be safely started using this coupling. Unloaded conveyors can be run at creep speed.
When combined with reliable mechanics, hydrodynamic power transmission provides very high system availability. The TurboBelt itself offers availability of up to 99.8 per cent, according to the manufacturer. An L10 bearing service life of 80,000 hours helps to achieve this high level of availability. The maintenance required is very low – for example, the first overhaul is due in approximately 10 to 15 years. The supply of spare parts is also guaranteed throughout the entire product service life.
The coupling is designed for use under even extremely harsh environmental conditions. It can be used in areas from the Arctic Circle to the Equator, in the desert or the tropical rain forest. This latest coupling technology has already won over a Brazilian mine operator. Voith TurboBelt couplings are used by them with belt conveyors to transport iron ore. Other key markets are the USA, Canada, South America, Australia and South Africa.
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