There are many types of CNC systems for CNC machine tools, but no matter what kind of CNC system, the following methods can be used to comprehensively judge the failure when a failure occurs.
(1) Intuitive method: It is to use human senses to pay attention to the phenomenon when the failure occurs and to judge the possible part of the failure. If there are abnormal noises or sparks when there is a fault, where there is a burnt position, and where there is an abnormal phenomenon of heat, then further observe the surface condition of each circuit board that may be malfunctioning, such as whether there is any on the circuit board Check whether there is any scorched, blackened or cracked electronic components to further narrow the scope of inspection. This is a basic and simple method, but it requires machine tool maintenance personnel to have certain maintenance experience.

(2) Use the hardware alarm function of the numerical control system: the alarm indicator can judge the fault. There are many alarm indicators on the hardware circuit board of the CNC system, which can roughly determine the location of the fault.

(3) Make full use of the software alarm function of the CNC system: all CNC systems have a self-diagnosis function. During system operation, the self-diagnostic program can be used to quickly diagnose the system. Once a fault is detected, the fault will be displayed on the form screen in the form of an alarm or various alarm lights will be lit. During maintenance, the fault of the machine tool can be found according to the alarm content.

(4) Diagnosis function using status display: The CNC system can not only display fault diagnosis information, but also provide various statuses of machine tool diagnosis in the form of diagnostic address and diagnostic data. For example, it provides the interface between the system and the machine tool. The input/output signal status, or the input/output signal status of the interface between the PC and the CNC device, and the PC and the machine tool, use the status display on the screen to check whether the CNC system inputs the signal to the machine tool or the machine tool. Whether the switch information has been input to the CNC system. In short, the fault can be distinguished whether it is on the side of the machine tool or the side of the CNC system, so that the inspection scope of the CNC machine tool can be reduced.

(5) When a failure occurs, the CNC system parameters should be checked in time: system parameter changes will directly affect the performance of the machine tool, and even cause the machine tool to fail and the entire machine tool cannot work. The external interference may cause the changes of individual parameters in the memory. It seems that when some inexplicable failures occur in the machine tool, the parameters of the CNC system can be checked.

(6) Spare parts replacement method: When the machine tool failure is analyzed and it is found that the circuit board may be faulty, the spare part board can be used to replace it, and the faulty circuit board can be quickly determined. However, the following two points should be noted when using this method: ①Pay attention to the position of the adjustable switches on the circuit board. When changing the board, pay attention to the setting status of the two circuit boards to be exchanged. Make the system in an unstable or not state, or even an alarm. ②After replacing some circuit boards (such as CCU boards), it is necessary to reset or input the parameters and programs of the machine tool.

(7) Utilize the detection terminals on the circuit board: there are detection terminals for measuring the circuit voltage and waveform on the circuit board, so as to determine whether the part of the circuit is working properly during debugging and maintenance. But when testing this part of the circuit, you should be familiar with the principle of the circuit and the logical relationship of the circuit. In the case of unfamiliar logical relationships, two identical circuit boards can be compared for testing, so as to find the fault of the circuit board.
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