We all know that the imbalance of the motor rotor is the main cause of motor failure. To ensure the normal operation of the motor, dynamic balance testing of the rotor is necessary. So, what should be done for rotor dynamic balance testing?
Rotor dynamic balance detection refers to an experiment that uses the principle of balance to correct the imbalance of a rotor. It is mainly applicable to single rotor, double rotor, multi blade impeller, blade impeller, and hub impeller.
1、 Selection of balancing machines
1. The sensitivity of the balancing machine, the higher the sensitivity, the higher the balancing accuracy.
2. The resolution of a balancing machine is an important factor determining its sensitivity. In general, the higher the resolution, the better the balancing machine.
3. The measurement range of the balancing machine refers to the maximum measurable range of the measuring head of the balancing machine. If the measurement range is too small, it will affect the balance accuracy.
4. The accuracy level of the balancing machine should be selected based on the product requirements, as different products have different requirements for the accuracy of the balancing machine.
5. The speed of the balancing machine mainly refers to the movement speed of the measuring head of the balancing machine. When performing dynamic balancing, the speed must be slow, otherwise it will affect accuracy.
There are many types of sensors for balancing machines, such as photoelectric encoders, magnetic particle sensors, current sensors, etc. The detection accuracy varies depending on the type of sensor. When choosing a balancing machine, we need to decide which sensor to use based on the specific situation.
2、 Balance correction
When the rotor is in static balance, due to the presence of imbalance, the rotor will experience horizontal vibration.
During dynamic balancing, the centrifugal force (i.e. balance force) generated by the horizontal vibration caused by the imbalance is directly proportional to the rotational inertia of the rotor. Therefore, the correction of rotor imbalance can be achieved by increasing the support stiffness (or adjusting the support position) and reducing the balance force to achieve the required imbalance.
3、 Trial weight
Test weight is a commonly used method for dynamic balance testing, and it is generally necessary to conduct a test weight when conducting dynamic balance testing, as not conducting a test weight can affect the accuracy of the test results.
1. The test weight should be carried out between the test weight surface and the tested rotor, that is, the shoulder or side of the tested rotor, and the test weight surface should be parallel to the shoulder or side surface of the shaft.
2. The test weight should be placed on the tested rotor and at a certain angle to the shoulder or side surface of the shaft.
4. The test weight cannot be placed on the surface of the rotor.
4、 Dynamic balance detection
Balance correction refers to adding a larger weight to the rotor to minimize the centrifugal force that may cause imbalance at the balanced speed. During the rotation process, the mass cannot be completely transferred to the rotor, but is dispersed in a certain area near the rotor axis. When the rotor stops rotating, the mass will be evenly distributed throughout the entire rotor axis, reaching a new equilibrium state.
5、 Data processing
When processing data, the following points should be noted:
1. The balanced rotor should reach a balanced state, otherwise it needs to be corrected.
2. The measured points of the balanced rotor should be on the same horizontal plane. If the imbalance value is greater than a certain value, it is considered that the rotor is unbalanced.
3. The imbalance value of each measuring point should be calculated and their average value should be calculated.
4. For the rotating part of the rotor, a dynamic balance test is generally required to verify whether it meets the usage requirements.
5. For rotors with imbalance, it should be considered to increase the number of dynamic balance tests appropriately.
6. Pay attention to the impact of imbalance measurement errors on the experimental results.
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