The servo drive system of CNC machine tools includes spindle drive and feed drive. Both are divided into two types of DC and AC different devices.
1. Feed drive system fault handling:
According to statistics, this part of the failure rate accounts for about l/3 of the total failure rate of CNC machine tools. Symptoms fall into three general categories:
Software alarm phenomenon: Including servo feed system error alarm (mostly caused by failure of speed control unit or failure of main control printed circuit board and position control or servo signal related parts), detection elements (such as tachogenerator, rotation) Faults such as transformers or pulse encoders, faults caused by detection signals, overheating alarms (including overheating of the servo unit, overheating of the transformer, and overheating of the servo motor).
Hardware alarm phenomenon: including high-voltage alarm (grid voltage instability), high-current alarm (breakage of thyristor), low voltage alarm (mostly input voltage is lower than 85% of rated value or bad power cable connection), overload alarm (mechanical The load is too large), the speed feedback disconnection alarm, and the protective switch action are incorrect. These faults should be treated separately according to the specific circumstances in the process.
· Failure phenomena with no alarm display: Including machine out of control, machine tool vibration, machine tool overshoot (incorrect parameter settings), excessive noise (motor failure), instability in fast forward, etc. These faults should be investigated from the aspects of inspection speed control unit, parameter setting, transmission pair clearance, foreign material immersion, motor axial turbulence, and bad brush contact.
2. Spindle drive system fault handling:
Spindle drive system failure generally has the following aspects
• Failure of the DC spindle control system: Including spindle stop rotation (trigger line fault), abnormal spindle speed (tachometer generator fault or D/A converter malfunction), main motor vibration or excessive noise (phase sequence incorrect or There is an error in the power frequency setting, an over-current alarm, an excessive speed deviation (the load is too large, or the spindle is braked).
· Faults of the AC spindle control system: Including motor overheating fault (exceeding load, excessively dirty cooling system, damage of cooling fan, bad connection between motor and control unit, etc.), AC input circuit and regeneration circuit fuse blown (This type of fault causes More: If the impedance is too high, the surge absorber is damaged, the power rectifier bridge is damaged, the transistor module used in the inverter is damaged, the printed circuit board of the control unit is damaged, the motor acceleration and deceleration frequency is too high, the main motor vibrates, and the noise is excessive , motor speed is too high or normal speed and other failures.
To deal with these faults, you must first find out the source of the fault from the start of detection, find out and analyze the cause of the fault, and take measures to troubleshoot the fault. If the motor vibrates, it must first confirm under what conditions this phenomenon occurs. If it occurs during deceleration, the fault must occur in the regeneration circuit. At this time, it is necessary to check whether the fuse of the circuit has been blown, or the The transistor is damaged. If it is generated at a constant speed, check whether the feedback voltage is normal or not. Then, cut off the command and check if there is abnormal noise during motor stop. If so, it is certain that the failure occurred in the mechanical part, or on the printed circuit board. If the feedback voltage is abnormal, you should first check whether the vibration cycle is related to speed. If relevant, check whether the connection between the spindle and the spindle motor is faulty, and whether the spindle and the pulse generator installed at the rear of the AC spindle motor are damaged. No, the fault may be generated on the printed circuit board. You need to check the board or readjust it. It may also be produced mechanically and it is a mechanical failure.
In short, we must have patience, nuanced inspection, testing, and
Analysis, of course, has accumulated more experience and is easier to judge.
1. Feed drive system fault handling:
According to statistics, this part of the failure rate accounts for about l/3 of the total failure rate of CNC machine tools. Symptoms fall into three general categories:
Software alarm phenomenon: Including servo feed system error alarm (mostly caused by failure of speed control unit or failure of main control printed circuit board and position control or servo signal related parts), detection elements (such as tachogenerator, rotation) Faults such as transformers or pulse encoders, faults caused by detection signals, overheating alarms (including overheating of the servo unit, overheating of the transformer, and overheating of the servo motor).
Hardware alarm phenomenon: including high-voltage alarm (grid voltage instability), high-current alarm (breakage of thyristor), low voltage alarm (mostly input voltage is lower than 85% of rated value or bad power cable connection), overload alarm (mechanical The load is too large), the speed feedback disconnection alarm, and the protective switch action are incorrect. These faults should be treated separately according to the specific circumstances in the process.
· Failure phenomena with no alarm display: Including machine out of control, machine tool vibration, machine tool overshoot (incorrect parameter settings), excessive noise (motor failure), instability in fast forward, etc. These faults should be investigated from the aspects of inspection speed control unit, parameter setting, transmission pair clearance, foreign material immersion, motor axial turbulence, and bad brush contact.
2. Spindle drive system fault handling:
Spindle drive system failure generally has the following aspects
• Failure of the DC spindle control system: Including spindle stop rotation (trigger line fault), abnormal spindle speed (tachometer generator fault or D/A converter malfunction), main motor vibration or excessive noise (phase sequence incorrect or There is an error in the power frequency setting, an over-current alarm, an excessive speed deviation (the load is too large, or the spindle is braked).
· Faults of the AC spindle control system: Including motor overheating fault (exceeding load, excessively dirty cooling system, damage of cooling fan, bad connection between motor and control unit, etc.), AC input circuit and regeneration circuit fuse blown (This type of fault causes More: If the impedance is too high, the surge absorber is damaged, the power rectifier bridge is damaged, the transistor module used in the inverter is damaged, the printed circuit board of the control unit is damaged, the motor acceleration and deceleration frequency is too high, the main motor vibrates, and the noise is excessive , motor speed is too high or normal speed and other failures.
To deal with these faults, you must first find out the source of the fault from the start of detection, find out and analyze the cause of the fault, and take measures to troubleshoot the fault. If the motor vibrates, it must first confirm under what conditions this phenomenon occurs. If it occurs during deceleration, the fault must occur in the regeneration circuit. At this time, it is necessary to check whether the fuse of the circuit has been blown, or the The transistor is damaged. If it is generated at a constant speed, check whether the feedback voltage is normal or not. Then, cut off the command and check if there is abnormal noise during motor stop. If so, it is certain that the failure occurred in the mechanical part, or on the printed circuit board. If the feedback voltage is abnormal, you should first check whether the vibration cycle is related to speed. If relevant, check whether the connection between the spindle and the spindle motor is faulty, and whether the spindle and the pulse generator installed at the rear of the AC spindle motor are damaged. No, the fault may be generated on the printed circuit board. You need to check the board or readjust it. It may also be produced mechanically and it is a mechanical failure.
In short, we must have patience, nuanced inspection, testing, and
Analysis, of course, has accumulated more experience and is easier to judge.
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