nsracing
Samba Member
Joined: November 16, 2003
Photos: 332
Location: NOVA
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| couple unbalance |
Posted: Sun Feb 08, 2009 7:47 am Views: 215
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Two unbalances (shown as arrows in the illustration) may have the same magnitude, but the direction may be offsett by 180 degrees relative to each other. This state of unbalance can no longer be determined by rolling a component on knife-edges, as the rotor will not settle in a clearly defined position.
The rotating component will wobble about its vertical axis (perpendicular to the axis of rotation), as the two unbalances generate a moment in the workpiece. This type of unbalance is therefore referred to as couple unbalance.
To correct a couple unbalance, you need to generate an opposed moment, e. g. you need two correction weights, arranged at a specific distance relative to each other. In the balancing planes thus defined, you either have to remove a specific amount of material, or add an appropriate weight at the opposite side.
Couple unbalance is usually encountered in long, cylindrical rotors. Therefore, horizontal balancing machines are usually best suited to correct dynamic unbalance. (Shenck) |
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