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• Time of issue:2020-08-14
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(Summary description)Servo motors are one of the important components used in current drive equipment. There are many types and brands of servo motors. Among them, FANUC and Mitsubishi's servo motors are the most widely used. When we use the servo motor, we often have some small faults because of the long time of use. I have sorted out these small faults. Although it is not as good as the company's professional maintenance personnel, it can also be used as a preliminary understanding.

Servo motor repair

Observe whether sparks are generated between the carbon brush and the commutator when the motor is running and the degree of sparks to repair:

1. There are only 2 to 4 tiny sparks. If the surface of the commutator is flat at this time. In most cases, repair is not necessary;

2. There is no spark. No need to repair;

3. There are more than 4 very small sparks, and there are 1 to 3 large sparks, you don't need to disassemble the armature, just use sandpaper to grind the carbon brush commutator;

4. If there are more than 4 large sparks, the commutator needs to be polished with sandpaper, and the carbon brush and armature must be removed. Replace the carbon brush and polish the carbon brush.

Repair of commutator:

1. The surface of the commutator is obviously uneven (touch by hand) or sparks when the motor is running, as in the fourth case. At this time, the armature needs to be disassembled and the converter is processed with a precision machine tool;

2. It is basically flat, but there are very small scars or sparks. For example, in the second case, l mouth 1 is hand-grinded with water sandpaper without disassembling the armature. The order of grinding is: first press the outer circle of the commutator Radial, process a wooden tool, cut several different thickness of water sandpaper into strips as wide as the commutator, and remove the carbon brush (please pay attention to the carbon brush groove on the handle of the removed carbon brush Make a mark on the top to ensure that the left and right are not changed during installation. Use a wooden tool wrapped with sandpaper to fix the commutator, press the motor rotation direction with the other hand, and gently rotate the shaft commutator to grind. Servo motor repairs use the order of the thickness of sandpaper to be coarser and then finer. When a piece of sandpaper is too blind to use, change to a finer sandpaper until the fine water sandpaper (or metallographic sandpaper) is used up.

How to align the servo motor encoder phase with the rotor magnetic pole phase zero point:

1. Phase alignment of incremental encoder

The alignment method between the phase of the UVW electronic commutation signal of the incremental encoder with commutation signal and the phase of the rotor magnetic pole, or the electrical angle phase, is as follows:

(1) Use a DC power supply to pass a DC current less than the rated current to the UV winding of the motor, U input, V output, and orient the motor shaft to a balanced position;

(2) Observe the U-phase signal and Z signal of the encoder with an oscilloscope;

(3) Adjust the relative position of the encoder shaft and the motor shaft;

(4) While adjusting, observe the transition edge of the encoder U-phase signal and the Z signal until the Z signal is stable at a high level (here the normal state of the Z signal is low by default), lock the encoder and motor Relative position relationship

(5) Twist the motor shaft back and forth, after letting go, if the Z signal can be stabilized at a high level every time the motor shaft freely returns to the equilibrium position, the alignment is valid.

2. Phase alignment of absolute encoder

The phase alignment of the absolute encoder is not much different for single-turn and multi-turn. In fact, the phase alignment of the encoder is aligned with the phase of the electrical angle of the motor within one turn. The current practical method is to use the EEPROM inside the encoder to store the measured phase after the encoder is randomly installed on the motor shaft. The specific method is as follows:

(1) Install the encoder on the motor randomly, that is, consolidate the encoder shaft and motor shaft, as well as the encoder shell and motor shell;

(2) Use a DC power supply to pass a DC current less than the rated current to the UV winding of the motor, U input, V output, and orient the motor shaft to a balanced position;

(3) Use the servo drive to read the single-turn position value of the absolute encoder and store it in the EEPROM that records the initial phase of the electrical angle of the motor inside the encoder;



(4) The alignment process ends.

Foshan Chuangchi Electromechanical Equipment Co., Ltd. is a company specializing in the sales of FANUC and MITSUBISHI CNC machine tool control system accessories. At the same time, it provides customers with CNC equipment maintenance, providing fanuc servo motor repair, Fanuc CNC System repair, FANUC servo drive repair, FANUC servo motor repair, FANUC system acc