The machine tool spindle refers to the shaft on a machine tool that drives the workpiece or cutting tool to rotate. The machine tool spindle typically consists of a spindle, bearings, and transmission components (gears or belt wheels). In practical applications, there are mainly two types of high-speed spindles:
One type is the high-speed electrical spindle with zero transmission. Due to its integrated structure of the motor and machine tool spindle and precise dynamic balance correction, this type of spindle has good rotation accuracy and stability, but it has limitations on output torque and power.
The other type is a spindle that combines a variable frequency spindle motor with a mechanical transmission mechanism. This type of spindle has much greater output torque and power, but relatively speaking, its rotation accuracy and stability are slightly worse. Therefore, for this type of spindle, how to correctly design the machine tool spindle and its components is crucial to the machining accuracy of the machine tool.
Common faults and solutions for CNC machine tool spindles:
I. The spindle without a frequency converter does not rotate
Fault causes and treatment methods:
① Mechanical transmission failure: Check for any break in the belt drive or whether the machine is in neutral.
② The three-phase power supply to the spindle is missing a phase or reversed: Check the power supply and swap any two power lines.
③ Incorrect circuit connection: Carefully refer to the circuit connection manual to ensure correct wiring.
④ The system does not output the corresponding spindle control signal: Use a multimeter to measure the system signal output terminal. If there is no spindle control signal output, replace the relevant IC components or send it for repair.
⑤ The system outputs the corresponding spindle control signal, but there is a breakage or component damage in the power supply circuit and control signal output circuit: Use a multimeter to check the power supply circuit between the system and the spindle motor, the signal control circuit for any breaks; whether the contacts between the connections are poorly connected; whether the AC contactor or DC relay is damaged; check if the thermal relay is overcurrent; check if the fuse is burned out, etc.
II. The spindle with a frequency converter does not rotate
Fault causes and treatment methods:
① Mechanical transmission failure: Check for any break in the belt drive or whether the machine is in neutral.
② The three-phase power supply to the spindle is missing a phase: Check the power supply and swap any two power lines.
③ The CNC system's inverter control parameters are not enabled: Consult the system manual to understand the inverter parameters and make changes.
④ Incorrect wiring connection between the system and the inverter: Consult the connection manual for the system and the inverter to ensure correct wiring.
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 connection is correct or poorly connected, and whether the inverter receives a matching analog voltage.
⑥ Breakage or component damage in the high-voltage control part: Check the reliability of the contacts in the spindle power supply circuit, whether there is any breakage in the circuit, whether the DC relay is damaged, or whether the fuse is burned out.
⑦ The inverter parameters are not adjusted properly: The inverter contains control method selections, such as inverter panel control of the spindle mode, NC system control of the spindle mode, etc. If the NC system control method is not selected, the system cannot control the spindle. Modify this parameter; check whether the related parameter settings are reasonable.
III. The spindle (gear-shift spindle) without a frequency converter has uncontrolled speed
Fault causes and treatment methods:
① The system does not output the S01-S04 control signal: Check whether the system has a gear-shift control signal output. If not, it is a system fault, replace the IC or send it for repair.
② Connection line fault: If the system has a gear-shift control signal output, check for any breaks or poor connections in the various connection lines, 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 properly.
IV. The spindle has no braking
Fault causes and treatment methods:
① Abnormal braking circuit or damage to high-voltage components: Check whether the bridge rectifier, fuse, and AC contactor are damaged; check whether there is a break in the high-voltage circuit.
② Insufficient braking time: Adjust the braking time parameter of the system or inverter.
③ The system does not output a braking signal: Replace the internal components or send it for repair.
④ The inverter control parameters are not adjusted properly: Consult the inverter manual to correctly set the inverter parameters.
V. The spindle stops immediately after starting
Fault causes and treatment methods:
① The system's output pulse time is insufficient: Adjust the M code output time of the system.
② The inverter is in the jog state: Refer to the inverter manual
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