The machine tool spindle refers to the axis that drives the workpiece or tool to rotate on the machine tool. The machine tool spindle is usually composed of a spindle, bearings, and transmission parts (gears or pulleys). There are two main types of high-speed spindles in practical applications:
One is a high-speed electric spindle with zero transmission. This type of spindle has good rotation accuracy and stability because it adopts an integrated structure of the motor and the machine tool spindle and undergoes precise dynamic balance correction, but the output torque and power are limited.
The other type is a spindle that combines a variable frequency spindle motor with a mechanical speed change mechanism. The torque and power output of this type of spindle are much greater, but the rotation accuracy and stability are relatively worse. Therefore, for this type of spindle, how to correctly design the machine tool spindle and its components to affect the machining accuracy of the machine tool is crucial.
Common faults and solutions for CNC machine tool spindles
1. The spindle without frequency conversion does not rotate
Causes of the fault and treatment methods:
① Caused by mechanical transmission failure: Check whether the belt drive is broken or whether the machine tool is in neutral gear.
② The three-phase power supply to the spindle is missing or reversed: check the power supply and swap any two power lines.
③ Circuit connection error: carefully refer to the circuit connection manual to ensure that the connection is correct.
④ The system has no corresponding spindle control signal output: use a multimeter to measure the system signal output terminal. If there is no spindle control signal output, it is necessary to replace the relevant IC components or send it to the factory for repair.
⑤ The system has corresponding spindle control signal output, but the power supply line and control signal output line are broken or the components are damaged: use a multimeter to check the power supply circuit between the system and the spindle motor, whether the signal control circuit is broken; whether the contacts between the connecting lines are in poor contact; whether the AC contactor and DC relay are damaged; check whether the thermal relay is overcurrent; check whether the fuse is burned, etc.
2. The spindle with inverter does not rotate
Fault causes and treatment methods:
① Caused by mechanical transmission failure: check whether the belt drive is broken or whether the machine tool is in neutral.
② The three-phase power supply to the spindle is missing: check the power supply and swap any two power lines.
③ The inverter control parameters of the CNC system are not turned on: check the system manual, understand the inverter parameters and change them.
④ The line connection between the system and the inverter is wrong: check the wiring manual of the system and the inverter to ensure that the connection is correct.
⑤ Abnormal analog voltage output: 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 has poor contact, and whether the analog voltage received by the inverter matches.
⑥ The strong power control part is broken or the components are damaged: check whether the contacts of the spindle power supply circuit are connected reliably, whether the circuit is broken, whether the DC relay is damaged, and whether the fuse is burned out.
⑦ The inverter parameters are not adjusted properly: the inverter contains control mode selection, which is divided into inverter panel control spindle mode, NC system control spindle mode, etc. If the NC system control mode is not selected, the system cannot control the spindle and modify this parameter; check whether the relevant parameter settings are reasonable.
3. The speed of the spindle (shift spindle) without frequency conversion is not controlled.
Fault cause treatment method:
① The system has no S01-S04 control signal output: Check whether the system has a shift control signal output. If not, it is a system fault, replace the IC or send it to the factory for repair.
② Connection line fault: If the system has a shift control signal output, check whether there is a circuit break or poor contact in each connection line, and check whether the DC relay or AC contactor is damaged.
③ The spindle motor is damaged or short-circuited: Check the spindle motor.
④ The machine is not in gear: engage the gear.
4. The spindle has no brake
Fault cause treatment method:
① The brake circuit is abnormal or the high-voltage components are damaged: Check whether the bridge pile, fuse, and AC contactor are damaged; check whether the high-voltage circuit is open.
② The braking time is not long enough: adjust the braking time parameters of the system or inverter.
③ The system has no brake signal output: replace internal components or send it to the factory for repair.
④ The inverter control parameters are not adjusted properly: refer to the inverter manual and set the inverter parameters correctly.
5. The spindle stops immediately after starting.
Fault cause handling method:
① The system output pulse time is not enough: adjust the system M code output time.
② The inverter is in jog state: refer to the inverter manual and set the parameters.
③ The control components of the spindle circuit are damaged: 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.
④ The spindle motor is short-circuited, causing thermal relay protection: find the cause of the short circuit and reset the thermal relay.
⑤ The spindle control circuit does not have a self-locking circuit, but sets the parameters to pulse signal output, so that the spindle cannot operate normally: change the system control spindle start and stop parameters to level control mode.
6. The spindle rotation cannot stop.
Fault cause handling method:
The AC contactor or DC relay is damaged, long-term traction, and cannot be controlled: replace the AC contactor or DC relay.
