Saturday, July 11, 2009

Balancing

Balancing

There are more than one hundred years of history of balancing machine development. Germany’s Siemens invented motor in 1866. Four years later, Canadian Henry Martinson applied balance technology patent begins balancing adjustment industry. Dr. Franz Lawaczek brought modified balancing technology in Germany in 1907. All balancing procedures are conducted in pure mechanical balancing equipment. Adopt resonance speed of vibration system in rotor’s balancing rotate speed usually to reach the maximum amplitude. It’s insecure and has large measuring error in such method for measuring rotor balance.

Accompany with the popularity of electronic technology development and rigidity rotor balancing theory, we adopt electronic measuring technology in most balancing equipments after 1950s. Balancing machine with plane separation circuit technology effectively eliminates interactive infection between left and right sides of balancing work piece. The appearance of hard bearing balancing machine can be recognized as a leap in balancing machine development history until 1970s. It eliminates inconvenience for the frequent dynamic adjustments of traditional soft bearing balancing machine, forms permanent bench mark balancing machine by adopting enactment of balancing dimension in static. In 1980s, piezoelectricity transducer brought another revolution to balancing machine. Balancing machine adopted such technology basically replaces soft bearing balancing machine in balancing field which is unnecessary to work in high speed. After 1990s, soft bearing balancing machine widely applied in some special fields accompany with rapid advancement of integrated circuit and computer technology.

One common definition of balancing is when the mass centerline and the rotational centerline of a rotating part are equal. Another definition is when zero vibratory force or motion is imparted from the rotating part to the bearing .

Balancing is the process of attempting to improve the mass distribution of a rotor, so that it rotates in its bearings without uncompensated centrifugal force. This usually done by adding compensating masses to the rotor at prescribe locations. It can also be done by removing fixed quantities of material, for example by drilling .

The balancing of rotating bodies is importance to avoid vibrations. In heavy industrial machine such as steam turbines and electric generators, vibration could cause catastrophic failure. Vibrations are noisy and uncomfortable and when a car wheel is out of balance, the ride is quite unpleasant. In this case of a simple wheel, balancing simply involves moving the centre of gravity to the center of rotation but as we shall see, for longer and more complex bodies, there is more to it.

A balancing machine is a measuring tool used for balancing rotating machine parts such as rotors for electric motors, fans, turbines, propellers and pumps. The machine usually consists of two rigid pedestals, with suspension and bearings on top. The unit under test is placed on the bearings and is rotated either with a belt or end-drive. As the part is rotated, the vibration in the suspension is detected with sensors and that information is used to determine the amount of unbalance in the part. Along with phase information, the machine can determine how much and where to add weights to balance the part.

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