Have you encountered this? With the CNC machining center of Fanucoi, during the machining process, the spindle rotation speed is abnormal, and the speed displayed by the system is unstable, fast and slow.
I. CNC machining center preparation before spindle maintenance
The spindle speed is abnormal, that is, after the spindle has given the speed command, the speed feedback from the CNC machining center machine tool is not consistent with the command speed (usually less than the command speed) or the spindle does not rotate smoothly. “The sound appears, fast and slow, and in some cases, the motor may even have an overcurrent alarm. When the spindle of the CNC machine tool has feedback from the encoder, the speed command “S” given by the CNC machining center machine tool is followed by a number, that is, the value that is fed back to the system display is the same. The main drive of the main shaft can be driven by a belt or by a gear. Most of them are driven by a synchronous belt in the belt drive. If the speed is abnormal, it may be because the synchronous installation is too long, so the belt slips. At the same time, the connection between the main shaft and the main shaft encoder also uses a synchronous belt, and there is also the possibility of losing steps in this link. The poor lubrication of the main shaft or the burning of any bearings on the main shaft results in excessive resistance of the machine tool and makes the main shaft not rotate smoothly. This can also be caused by external signal intervention.

2. Pre-repair survey of CNC machining center.
The machining center is idling and only changes in one direction or when the spindle rotates at a low speed. The spindle rotation speed is not lost, but it is lost when changing direction or cutting materials when the spindle is moving rapidly, especially at large cutting depths More obvious.
Third, analyze the reasons
1.The signal sent from the CNC machining center system to the spindle servo amplifier (inverter) is blocked during transmission;
2.The circuit voltage is unstable;
3.The timing belt transmitting the spindle to the main shaft is too long or wears out and causes slipping;
4.The main shaft and the main shaft encoder’s timing belt are too long or worn to cause slipping;
5.The signal line from the encoder to the servo amplifier or system is subject to external interference;
6.The two sets of bearings supporting the main shaft are burned out;
7.Poor lubrication of the spindle of CNC machining center.

Fourth, determine the steps to troubleshoot the spindle of the CNC machining center
1. Use a multimeter to measure the voltage of the CNC machining center. It is found that the voltage is normal, and the other machine tools next to it are working normally with the electricity of the same power grid. The reason for the voltage instability can be ruled out.
2. Check that the amount of lubricating oil in the CNC machining center is within the normal working range, the lubrication system is working properly, and the oil circuit is free of oil leakage and open circuit failures, and troubleshoot the lubrication.
3. There is no problem with lubrication, it may be caused by poor bearing movement. When the spindle of the CNC machining center is running, use a long rod (usually a screwdriver) to lean on the approximate position where the spindle box is installed, and one (large (One end) lean on the ears of the maintenance staff and listen to the sound of the bearing when it is running. No abnormal sound is heard, and the possibility of the failure caused by the bearing can be ruled out.
4. There is no problem with the lubrication of CNC machining center, then the problem may be inside the headstock. Open the inside of the headstock, check the timing belt connection between the spindle motor and the spindle, and press the belt between the two pulleys with your hands to appear tight and fit. .
5. The spindle NC machining center has no problem with the connection of the timing belt between the motor and the spindle. When checking the timing belt between the spindle and the encoder, it is found that the timing belt has been worn out. After the new timing belt is replaced, the system shows that the spindle speed is normal. The spindle fault is cleared.