U par navrata smo se dotaknuli pitanja brzine vrtnje prilikom balansiranja turbo punjaca. Ne budi ljen krenuo sam malo citat po netu kaj se o tome pise, pa sam naisao na sljedece:
"There are basically two types of CHRA balancing, high speed (VSR) and low speed (balancing machine). The VSR (vibration sort rig) is a machine that uses compressed air to spin the assembled CHRA to a relatively high speed, while pressure oiling the bearings and sensing vibration of the unit. Small unbalance corrections are then made on the compressor nose or nut to fine or trim balance the unit.
Balancing machine CHRA balancing consists of mounting an assembled turbo CHRA in a conventional two plane dynamic balancing machine. The rotating assembly is then driven at a relatively low speed by belt or air, and unbalance readings are taken on both the compressor and turbine ends of the rotating assembly. Oil is not pressure fed into the turbo, as the shaft is prelubricated before the balancing operation. The low speed and short cycle time preclude the need for pressurized lubrication.
Either type of CHRA balancing will generally eliminate stackup unbalance to an acceptable degree. Machine balancing has a slight advantage, in that the rotating components are dual plane balanced, as opposed to single plane balancing with the VSR. The main advantage of the VSR is that the turbo has actually spun at high speed, so the operator may be able to hear unusual noises from the turbo, and in some cases the oil flow can be checked (though this is not very reliable.)
Another common misconception about balancing is that balancing at higher speeds results in closer balancing. This is not inherently true. A rigid rotor that is out of balance by 10 milligram inches at 1000 RPM will be out of balance by 10 milligram inches at 100,000 RPM. The force created by a given amount of unbalance increases exponentially as speed increases, but the absolute amount of unbalance does not. It is critical that the balancing equipment being used has sufficient sensitivity to balance the rotor to the necessary tolerance at the desired balancing speed, but balancing at operational speed is rarely advantageous. The logistic and safety considerations of very high speed balancing rarely outweigh any accuracy gained."
The preceding article was written by Mark Bowman, President and CEO of Heins Balancing Systems, Inc. Heins is the world’s largest supplier of balancing equipment into the turbocharger aftermarket, and supplies both OEMs and aftermarket facilities worldwide. For more information, visit the Heins website at
www.heins-balancing.com.
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