Electrical Fault Diagnosis of CNC Machine Tool
Introduction
CNC (Computer Numerical Control) machine tools play an important role in modern manufacturing. The electronic system plays an important role in the CNC machine tool. Electrical faults are common in the use of the CNC machine tool, so it is important to correctly diagnose the cause of the fault and find out the corresponding measures. For example, the common electrical faults of CNC machine tools include: failure of the servo system, interruption of the software of the control system, failure of the power supply system, electromagnetic interference and so on. This paper introduces the common fault diagnosis methods of CNC machine tools.
Failure of Servo System
Servo system failure is mainly caused by problems in four parts: servo drive, servo motor, feedback element and signal transmission line.
1. Failed servomotor. The common fault phenomenon is that the servomotor does not rotate, the motor does not rotate, or the motor does not rotate properly. The reason for this failure may be that the motor is overloaded, the wiring is wrong, the brake is stuck, or the drive power supply is unstable. The diagnostic method is to check the power supply or external wiring, or to measure the variation of the current or voltage of the motor.
2. The feedback element is damaged. The common fault symptom is that the machine tool cannot move accurately or quickly, or the error of the motor does not decrease. The reason for this failure may be a loose connection, a broken connection, or a loose sensor output shaft. The diagnostic method is to check whether the wiring connection is wrong or the output part is working abnormally.
3. Abnormal servo drive failure. Common fault symptoms are abnormal current, failure to start, failure of synchronization, etc. The reason for this failure may be overload or unbalanced voltage. The diagnostic method is to measure the voltage of each part of the drive and check whether each contact point of the drive is normal.
4. The signal transmission line is poor contact. Common fault symptoms are disconnected, unstable speed, blocked axis, etc. The diagnostic method is to observe whether the signal cable wiring is loose, the connector position connection is wrong, and the signal line is short-circuited or weakened.
Control System Software Faults
Software faults are common in the control system of CNC machine tools. Common faults include software hanging, parameters damaged, and networking out of control.
1. Software hanging failure. Common fault symptoms are that the machine tool control system stops working and the display screen is blank. The reasons for the fault may be that the software has been damaged, overloaded, or infected by a virus. The diagnostic method is to check whether the machine tool software is damaged or not, reset the computer, and carry out system recovery or reinstall.
2. Parameter failure. Common fault symptoms include abnormal speed, servo alarm, etc. The cause of the fault may be that the program parameter is wrong or the parameter information is not written correctly. The diagnostic method is to analyze the fault parameter and modify the program parameter correctly.
3. Network control failure. Common fault symptoms are that the machine tool cannot communicate with other devices, the communication error occurs, or the control system cannot keep up with the network communication environment. The diagnostic method is to use the network detection line to detect whether the network signal line is normal or check the network parameters.
Power System Failure
The power system failure is caused by insufficient power supply, overvoltage, line interruption, surge pulse and other reasons. The common fault symptom is that the machine tool stops working suddenly. The diagnostic method is to first check whether the power supply line is normal, and then measure the voltage to see if the power supply is normal. If the power supply is normal, it is necessary to check whether the components of the power system are damaged or not.
Electromagnetic Interference
Electromagnetic interference is caused by strong electrical or magnetic fields close to the CNC machine tool. Common fault symptoms are unstable operation, speed inconsistency, overcurrent and so on. The diagnostic method is to analyze the source of the noise and the influence area, and then take shielding measures or enhance grounding.
Conclusion
This paper introduces the diagnosis methods of common electrical faults of CNC machine tools in detail.
First, we should find out the cause of the fault through detailed observation and analysis.
Second, we should use specific fault detection equipment and instruments to measure and analyze the fault phenomenon.
Finally, we should take corresponding measures to solve the fault, such as adjusting parameters, replacing parts, etc.
For the correct diagnosis and avoidance of the electrical fault of the CNC machine tool, it is necessary to have a certain understanding of the principle, performance and structure of the CNC machine tool, and it is also essential for people to have an understanding of relevant testing methods and instruments as well as effective fault prevention measures.
