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Although it is reasonable to use a high-speed or low-speed balancing machine to directly balance the various rotors in a normal state, the field balance may be required when the rotor is combined into a composite rotor series due to the influence of failure on actual machine or balancing machine. The unbalanced state of the rotor changes under the condition of during the whole machine working. It is also possible to balance the part during working. From the economic and technical aspects, under which circumstance there is a need to consider the portable balancer. First, there is no need to increase investment to purchase a balancing machine. Second, the balance machine cannot be placed to the work piece to correct the location or reach the requirements of the duration. Third, removing machine rotor part and transport to an applicable balancing equipment site is uneconomical.
In general, when the rotor diameter is 7 to 10 times larger than its length, it is usually treated as a single-plane rotor. In this case, in order to restore the rotor center of mass from the axis to the axial position, it is only necessary to place a correction mass that equal torque at any position opposite to the diameter of the center of mass. For diameters less than 7 to 10 Times the rotor, usually, as a double-plane rotor treatment. If there are two equal mass configuration at both ends of the axis and the axis of symmetrical position, then the rotor does not exist a center of gravity deviation from the shaft problem. However, once it is turned up, the centrifugal force produced by the two masses constitutes a couple effect, and the inertia axis does not coincide with the rotating shaft, causing the bearing to be violently vibrated. The inertia axis is tilted with the axis of rotation and the two masses are not symmetrical. That will result in the center of mass deviation from the axis, which is a common imbalance in the most actual double-plane rotors.
In order to determine the size and position of the corrected mass of the rotor to be calibrated, the mass distribution of the rotor is temporarily changed by the method of placing the test quality, and the vibration amplitude and phase change caused by the measurement are measured. The effect of the effect determines the size and placement of the correct quality of the correction.
At any point in the bearing, the centrifugal force generated by the rotor imbalance is periodically experienced at the same frequency as the speed. Therefore, in the vibration signal spectrum, we see the imbalance vibration increases in the performance of the vibration frequency at the vibration signal. Generally, a vibration sensor is placed on the rotor bearing housing to measure the vibration caused by the unbalance. The vibration signal at the frequency is proportional to the force produced by the unbalanced mass. In order to measure the phase and frequency, a speed sensor is required. The instrument uses a laser photoelectric speed sensor to reflect the position as a vibration signal phase reference point to determine the rotor’s unbalanced angle. In summary, the amplitude of the unbalanced vibration and the phase can be used to determine the equilibrium correction torque and the correction angle relative to the center of gravity on the test center, respectively. After the correction radius is selected, the placement and the correction mass value can be calculated from the corrected moment and angle.
The greatest advantage of on-site portable balancer is that it is possible to balance many types of compound rotors during onsite running, which will effectively reduce the serious impact of unbalance on mechanical equipment after overcoming the balance error. Thus Portable balancer is aiming at avoiding the occurrence of major machinery, personal accidents and increasing machine life. However, the engineering and technical persons who wish to participate in and visit on site should strictly carry out the on-site balancer operation regulations in accordance with the relevant international standards (ISO).