Seven methods of CNC machine tool fault diagnosis

Seven methods of CNC machine tool fault diagnosis

1. Isolation method The isolation method disconnects some control loops to narrow the fault area. Example: A machining zhong, in the JOG mode, the feed is smooth, but the automatic is not normal. First of all, to determine whether the NC fault or the servo system fault, first disconnect the servo speed given signal, use the battery voltage as a signal, the fault is still, indicating that the NC system is not a problem. On further inspection, the Y-clamp device is faulty.

2. Although modern CNC systems have not yet reached a high degree of intelligence, they already have a strong self-diagnosis function. The hardware and software of the CNC system can be monitored at any time. Once an anomaly is found, immediately display an alarm message on the CRT or indicate the approximate cause of the fault with a light emitting diode. Using the self-diagnosis function, it can also show the status of the interface signal between the system and the host, so as to determine whether the fault occurs in the mechanical part or the numerical control system part. This method is one of the effective methods in current maintenance work.

3. The components of the local temperature rising CNC system will age after long-term operation, and the performance will become worse. When they are not completely damaged, the failure will become intermittent. At this time, a hot hair dryer or electric soldering iron can be used to locally heat up the suspected components and accelerate their aging in order to expose the faulty parts. Of course, when using this method, we must pay attention to the temperature parameters of the components, and do not bake the original good devices.

4. When the fault performance of the CNC system is sometimes no, it is often possible to check the fault location by tapping, which is because the CNC system is composed of a number of printed circuit boards, each board has many solder joints, and the board or module is connected by connectors and wires. Therefore, any welding or poor contact may cause failure. When the insulation is gently knocked on the doubtful spot of welding and poor contact, the fault will certainly be repeated, if it occurs, the knock is likely to be the fault part.

5. Fault diagnosis using alarm number is one of the main methods of fault diagnosis of CNC machine tools. If the machine tool has a fault, and there is an alarm number displayed on the CRT, first of all, according to the content of the alarm number for the corresponding analysis and diagnosis. Maintenance personnel can analyze the phenomenon pointed out by the alarm number, narrow the scope of the inspection, and carry out a certain aspect of the inspection purposefully. Alarm number (error code) generally includes the following aspects of fault (or error) information: (1) programming error or operation error; (2) The memory is not working properly; (3) Servo system failure; (4) Programmable controller failure; (5) Connection failure; (6) Abnormal temperature, pressure, liquid level, etc.; (7) The state of the travel switch (or proximity switch) is incorrect. In addition to the above commonly used fault inspection test methods, there are pulling plate method, voltage deviation method, open loop detection method and so on. Including the above mentioned diagnostic methods, all these inspection methods have their own characteristics, according to different fault phenomena, you can choose several methods at the same time flexible application, comprehensive analysis of the fault, in order to gradually narrow the scope of the fault, faster troubleshooting. Once the fault part is found, but there is no replacement spare part on hand, it can be solved by transplantation borrowing method as an emergency measure.

6. Functional program testing method The so-called functional program testing method is the common functions and special functions of the numerical control system, such as linear positioning, circular interpolation, spiral cutting, fixed cycle, user macro program, etc., with manual programming or automatic programming methods, compiled into a functional test program, input into the numerical control system, and then start the numerical control system to run it. In order to check the accuracy and reliability of the machine tool to perform these functions, and then judge the possible causes of failure. This method is a better judgment method for the inspection of the long-term idle CNC machine tool di at the time of starting up and the waste caused by the machine tool processing but without alarm, it is difficult to determine whether the programming error or the operation error, or the cause of the machine tool failure.

Seven. In the design of the printed circuit board, in order to adjust and maintain the convenience, a number of detection terminals are designed on the printed circuit board. Users can also use these terminals to compare and measure the difference between a normal printed circuit board and a faulty printed circuit board. The voltage and waveform of these measuring terminals can be detected to analyze the cause of the fault and the location of the fault. Sometimes it is even possible to artificially create "faults" on normal printed circuit boards, such as disconnecting or short-circuiting, unplugging components, etc., to determine the cause of the real fault. To this end, maintenance personnel should accumulate the correct waveform and voltage value of the key parts or fault prone parts on the printed circuit board in normal times. Because CNC system manufacturers often do not provide information in this regard.