Analysis of key points of motor rotor dynamic balance detection

We all know that the imbalance of the motor's rotor is the main cause of motor failure. In order to ensure the normal operation of the motor, the rotor must be dynamically balanced. So, how to do the rotor dynamic balance test?

Rotor dynamic balancing test refers to a test that uses the balancing principle to correct the imbalance of the rotor. It is mainly suitable for single rotor, double rotor, multi-blade impeller, blade-type impeller and hub-type impeller.

1. Selection of balancing machine

1. The sensitivity of the balancing machine. The higher the sensitivity, the higher the balancing accuracy.

2. Resolution of the balancing machine. Resolution is an important factor that determines the sensitivity of the balancing machine. Generally speaking, the higher the resolution, the better the balancing machine.

3. The measuring range of the balancing machine refers to the maximum measurable range of the balancing machine probe. If the measuring range is too small, it will affect the balancing accuracy.

4. The accuracy level of the balancing machine. Since different products have different requirements for the accuracy of the balancing machine, the balancing machine should be selected according to the product requirements.

5. The speed of the balancing machine mainly refers to the moving speed of the balancing machine probe. The speed must be slow when doing dynamic balancing, otherwise it will affect the accuracy.

6. There are many types of sensors for balancing machines, such as photoelectric encoders, magnetic powder sensors, current sensors, etc. Different sensor types have different detection accuracy. When choosing a balancing machine, we must decide which sensor to use based on the specific situation.

2. Balance Correction

1. When the rotor is in static balance, it will vibrate horizontally due to the existence of imbalance.

2. During dynamic balancing, the centrifugal force (i.e., balancing force) of horizontal vibration generated by the imbalance is proportional to the rotor's rotational inertia. Therefore, the rotor imbalance correction can be eliminated by increasing the support stiffness (or adjusting the support position) and reducing the balancing force to achieve the required imbalance.

3. Test weight

Trial weighing is a commonly used method for dynamic balancing detection. Generally, trial weighing is required when performing dynamic balancing detection, because if trial weighing is not performed, it will affect the accuracy of the test results.

1. The test weight should be carried out between the test weight surface and the rotor to be tested, that is, the shaft shoulder or shaft side of the rotor to be tested. The test weight surface should be parallel to the shaft shoulder or shaft side surface.

2. The test weight should be placed on the rotor to be tested and form a certain angle with the shaft shoulder or shaft side surface.

4. The test weight cannot be placed on the rotor surface.

4. Dynamic balance detection

Balance correction refers to adding a large counterweight to the rotor to minimize the unbalanced centrifugal force of the rotor 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 on the entire rotor axis to achieve a new balance state. There are two main types of dynamic balancing tests:

5. Data Processing

When processing data, the following points should be noted:

1. The balanced rotor should reach a balanced state, otherwise correction is required.

2. After balancing, all measuring points of the rotor should be on the same horizontal plane. If the unbalance value is greater than a certain value, the rotor is considered to be unbalanced.

3. The unbalance 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 balancing test is generally required to check whether it meets the use requirements.

5. For rotors with imbalance, consideration should be given to appropriately increasing the number of dynamic balancing tests.

6. Pay attention to the impact of unbalance measurement errors on test results.