There are several ways to check the breakdown of CNC machine tools

1. Intuitive method This is the most basic method. The maintenance personnel can narrow down the fault to a module or a printed circuit board by observing various abnormal phenomena such as light, sound, and taste during the fault and carefully looking at each part of the system. This requires that maintenance personnel have a wealth of practical experience, and that they must have a wide range of knowledge and comprehensive judgment skills.
2. Self-diagnosis function method Although the modern numerical control system has not yet reached a high level of intelligence, it already has a strong self-diagnosis function. The status of the hardware and software of the CNC system can be monitored at any time. In the event of an abnormality, alarm information is immediately displayed on the crt or the LED is used to identify the general cause of the failure. The self-diagnosis function can also display the state of the interface signal between the system and the host, thereby determining whether the fault occurs in the mechanical part or the numerical control part, and indicates the rough part of the fault. This method is the most effective one when repairing. 3. Functional program test method The so-called function program test method is to compile a common function and special function of the numerical control system, such as linear positioning, circular interpolation, thread cutting, fixed cycle, user macro program, etc. The functional program test tape is fed into the CNC system by a tape reader, and then the CNC system is started to run, in order to check the accuracy and reliability of the machine to perform these functions, and then determine the possible cause of the failure. This method is difficult to determine whether it is a programming error or an operation error for a long-term idle CNC machine tool when it is turned on for the first time and when the machine tool processing results in a waste product but no alarm, or when the machine tool failure is judged to be a better one. method.
4. Exchange method This is a simple and easy method, and it is also one of the most commonly used methods for on-site judgment. The so-called exchange method is to analyze the general cause of the failure, maintenance personnel can use spare printed circuit boards, templates, integrated circuit chips or components to replace doubtful parts, thus reducing the scope of the fault to the printed circuit board or chip level. It is also actually validating the analysis. Before the standby board is switched, check whether the standby board is in good condition and check that the status of the standby board is exactly the same as that of the original board. This includes the selection switch on the check board, the setting position of the short bar, and the position of the potentiometer. When replacing the memory board of the cnc device, it is often necessary to initialize the memory of the system, and must strictly follow the requirements of the operation and maintenance instructions of the relevant system.
5. Transfer method The so-called transfer method is to exchange two printed circuit boards, modules, integrated circuit chips or components that have the same function in the cnc system and observe whether the fault phenomenon is transferred. With this, the fault location of the system can be quickly determined. This method is actually a kind of exchange method. Therefore, the relevant precautions are described in the Exchange Act.
6. Parameter inspection method As we all know, numerical control parameters can directly affect the function of CNC machine tools. The parameters are usually stored in the bubble memory or stored in the cmos ram to be held by the battery. Once the battery is insufficient or due to some external interference and other factors, individual parameters will be lost or changed, causing confusion, and the machine tool will not work properly. At this point, troubleshooting can be done by checking and correcting the parameters. When the machine tool idles for a long period of time, an abnormal phenomenon or failure and no alarm occurs for no reason, check and correct the relevant parameters according to the characteristics of the fault.
In addition, after a long-running CNC machine tool, due to the wear of its mechanical transmission components, the change in the performance of electrical components, etc., the relevant parameters need to be adjusted. The failure of some machine tools is often caused by the fact that some inappropriate parameters are not modified in time. Of course, these faults do not fall into the category of faults.
7. Measurement and comparison
Cnc system manufacturer—Hite NC designed a plurality of testing terminals on the printed circuit board for the convenience of adjustment and maintenance when designing printed circuit boards. The user can also use these terminals to compare the difference between a normal printed circuit board and a faulty printed circuit board. The voltage or waveform of these measuring terminals can be detected and the cause of the fault and the location of the fault can be analyzed. Even sometimes, it is also possible to artificially create "failures" for normal printed circuits, such as disconnecting wires or short circuits, dialing out components, etc. to determine the cause of a real failure. For this reason, the maintenance personnel should normally accumulate the correct waveforms and voltage values ​​of the critical parts or the fault-prone parts of the printed circuit board at normal times. Because cnc system manufacturers often do not provide information on this.
8. Percussion When the system appears to be faulty, it can be used to check where the fault is located. This is due to the fact that the cnc system consists of several printed circuit boards, each of which has many solder joints. The boards or modules are connected by connectors and cables. Therefore, any welding or poor contact may cause malfunction. When lightly tapping the point where there is a false weld and poor contact with the insulator, the fault will surely repeat.
9. Local warming
The components of the cnc system have to be aged after long-term operation, and the performance will deteriorate. When they are not completely damaged, the failures that occur are sometimes absent. At this time, a hot-air blower or a soldering iron may be used to locally warm up suspected components and accelerate their aging so as to completely expose the faulty components. Of course, when using this method, be sure to pay attention to the temperature parameters of the components, etc. Do not bake the original device.
10. The principle analysis method can logically analyze the logic level and characteristic parameters (such as voltage value or waveform) of each point according to the principle of the cnc system, and then measure, analyze and compare with a multimeter, logic pen, oscilloscope or logic analyzer. Thus locate the fault. Using this method, maintenance personnel are required to have a clear and deep understanding of the principle of the entire system or each circuit.
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