What is CNC Spindle
The axis that drives the workpiece or tool to rotate on the CNC machine tool is called the machine tool spindle. The machine tool spindle is generally composed of bearings, spindles, transmission parts (gears or pulleys) and so on.
In our actual applications, there are two types of high-speed spindles. One is a high-speed electric spindle with zero transmission. This type of spindle adopts an integrated structure of motor and machine tool spindle, and has precise dynamic balance correction. Therefore, it has good rotation accuracy and stability, but it also limits the output torque and power.
The other is a spindle that combines a variable frequency spindle motor and a mechanical speed change mechanism. The output power and torque of this type of spindle is much larger than other types, but its accuracy and stability are worse. Therefore, for this type of spindle, how to correctly design the machine tool spindle and its components? The machining accuracy of the machine tool has big impact.
During production, we need to make sure CNC spindle is working well to produce good quality parts, but what problem the CNC spindle might have and how to fix it?
How To Troubleshoot A Problem With The Spindle Of A CNC Machine Tool
The spindle does not have a frequency converter, the spindle does not rotate:
If it is suspected to be a mechanical transmission failure, we need to check whether the transmission belt is broken or whether the machine tool is in neutral;
If it is suspected that the three-phase power supply to the spindle is lacking phase or reversed phase, we need to check the power supply and exchange any two power lines;
If it is suspected that the circuit connection is wrong, we need to carefully refer to the circuit connection manual to ensure that the connection is correct;
If the system has no corresponding spindle control signal output, we can use a multimeter to measure the system signal output terminal. If there is no spindle control signal output, we need to replace the relevant IC components or repair;
If the system has corresponding spindle control signal output, but the power supply line and control signal output line are open or the components are damaged, then we can use a multimeter to check whether the power supply and signal control circuit between the system and the spindle motor is open Happening. Check whether the contacts between the wires are in poor contact; whether the AC contactor and DC relay are damaged; check whether the thermal relay is over-current; check whether the fuse is burned, etc.
The main shaft has a frequency converter, the main shaft does not rotate
- If it is suspected to be a mechanical transmission failure, we need to check whether the transmission belt is broken or whether the machine tool is in neutral gear;
- If it is suspected that the three-phase power supply to the spindle is lacking phase or reversed phase, we need to check the power supply and exchange any two power lines;
- If the inverter control parameters of the CNC system are not turned on, we need to consult the system manual to understand the inverter parameters and change them;
- If the line connection between the system and the inverter is wrong, we can refer to the connection manual of the system and the inverter to ensure that the connection is correct;
- If the analog voltage output is abnormal, we can use a multimeter to check whether the analog voltage output by the system is normal, check whether the analog voltage signal line is connected correctly or poorly, and whether the analog voltage received by the inverter matches;
- If the power control part is broken or the components are damaged, we can check whether the connection of each contact of the main shaft power supply line is reliable, whether the line is open, whether the DC relay is damaged, whether the fuse is burned out, etc.
- If the inverter parameters are not adjusted properly, then our inverter contains a variety of control methods, including inverter panel control spindle mode, NC system control spindle mode, etc. If the NC system control mode is not selected, then We cannot use the system to control the spindle, modify this parameter; check whether the relevant parameter settings are reasonable.
Uncontrolled spindle speed without frequency converter
- If the system has no control signal output of S01-S04, we can judge whether there is a problem by checking whether the system has a shift control signal output. If not, the system is faulty. It is recommended to replace the IC or repair it;
- If the connection line is faulty and the system has a shift control signal output, we need to check whether there is an open circuit or poor contact in each connection line, and check whether the DC relay or AC contactor is damaged;
- If the spindle motor is damaged or short-circuited, we can directly check the spindle motor;
- If it is because the machine is not in gear, just put it in gear.
No brake on spindle
- If it is because of abnormal braking circuit or damage of high-current components, we need to check whether there is any problem with the bridge stack, fuse, and AC contactor, and check whether the high-current circuit is open;
- If the braking time is not long enough, you only need to adjust the braking time parameters of the system or inverter;
- If the system has no brake signal output, we need to replace internal components or repair;
- If the control parameters of the inverter have not been adjusted well, we have to refer to the inverter manual and set the inverter parameters correctly
The spindle stops immediately after starting
- If it is because the system output pulse time is not enough, adjust the system’s M code output time;
- If it is because the inverter is in jog state, we can refer to the instruction manual of the inverter and set the parameters;
- If it is because the control components of the spindle circuit are damaged, we need to check whether the contacts on the circuit are in good contact, and check whether the DC relay and AC contactor are damaged, causing the contacts to not self-lock;
- If the main shaft motor is short-circuited, causing thermal relay protection, we need to find the cause of the short-circuit and reset the thermal relay;
- If the spindle control loop does not have a self-locking circuit, and the parameter is set to pulse signal output, so that the spindle cannot run normally, we only need to change the system control spindle start and stop parameters to level control mode.
Spindle rotation cannot be stopped
If it is because the AC contactor or DC relay is damaged, it will be closed for a long time and cannot be controlled. Then we only need to replace the AC contactor or DC relay.