What are the steps and methods to deal with the common faults of CNC grinding machines?

Numerical control grinder is a grinder that grinds the surface of workpiece with abrasive tools. Most grinders use high-speed rotating grinding wheels for grinding, and a few use other abrasive tools such as oilstone and abrasive belt and free abrasive materials for processing, such as honing machine, superfinishing grinder, abrasive belt grinder, grinder and polisher. There are CNC surface grinder, CNC centerless grinder, CNC internal and external grinder, CNC vertical universal grinder, CNC coordinate grinder, CNC forming grinder and so on.

With the rapid development of machining in China, there are more and more CNC grinders. Because of the advanced nature of CNC grinding machine and the instability of faults, and most faults appear in the form of comprehensive faults, the maintenance of CNC grinding machine is much more difficult, but the steps and methods of fault handling are nothing more than the following.

1. Fully investigate the fault site.

When a fault occurs, first of all, we should fully understand under what circumstances the grinding machine fault occurred, what happened, and what measures the operator took after it appeared. If the fault is still there, carefully observe the contents of CNC, understand the contents of the program segment being executed and the alarm content displayed by self-diagnosis, and observe the alarm lights on each circuit board. Then press the reset key of the system to see if the fault disappears. If the fault alarm disappears, this alarm is mostly a software fault.

2. List all factors that may lead to failure.

There may be many reasons for the same fault of CNC grinder, including mechanical, electrical, control system and many other factors, so all relevant factors should be listed in the fault analysis. For example, the X-axis of grinding machine will shake when moving, which may be caused by the following factors: A, the connecting wire of X-axis encoder may be in poor contact; B, the X-axis island rail is inserted too tightly, and the damping is too large, resulting in an excessive load on the X-axis motor; C. Whether the X-axis servo motor and screw coupling are loose or have gaps; There is something wrong with the servo drive of D-axis and X-axis motors; E, X-axis servo motor failure, etc.

3. How to determine the reasons for applause

There are many kinds of CNC systems for CNC grinding machines, but no matter which CNC system, the following methods can be used for comprehensive judgment when faults occur.

(1) intuitive method: it is to use human senses to pay attention to the phenomenon when the fault occurs and judge the possible location of the fault. If there are abnormal sounds, sparks, burnt positions and abnormal heat when faults occur, then it is necessary to further observe the surface conditions of each circuit board that may have faults, such as whether there are burnt and blackened circuit boards and whether electronic components burst, so as to further narrow the inspection scope. This is the most basic and simple method, but it requires grinder maintenance personnel to have certain maintenance experience.

(2) Using 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 numerical control system, which can roughly determine the location of the fault.

(3) Make full use of the software alarm function of CNC system: CNC system has self-diagnosis function. During the operation of the system, the self-diagnosis program can be used to quickly diagnose the system. Once the fault is detected, the fault will be displayed on the table screen immediately or the alarm light will be lit, and the fault of the grinder can be found according to the alarm content during maintenance.

(4) Diagnostic function of status display: CNC system can not only display fault diagnosis information, but also provide various status of grinder diagnosis in the form of diagnosis address and diagnosis data, such as providing input/output signal status of interface between system and grinder, or input/output signal status of interface between PC and CNC device, or between PC and grinder, that is, using status display screen can check whether CNC system has input signal to grinder or whether the switch information of grinder has been input. In a word, we can distinguish whether the fault is on the grinder side or on the CNC system side, thus narrowing the inspection scope of the CNC grinder fault.

(5) Check the parameters of the CNC system in time when a fault occurs: the change of system parameters will directly affect the performance of the grinder, and even cause the grinder to malfunction, and the whole grinder will not work. External interference may cause the change of individual parameters in the memory, so when there are some inexplicable faults in the grinder, you can check the parameters of the CNC system.

(6) Spare parts replacement method: When the grinder fault is analyzed and it is found that it may be a circuit board or even a fault, the spare parts board can be used for replacement, which can quickly determine the faulty circuit board. However, when using this method, we should pay attention to the following two points: ① Pay attention to the position of each adjustable switch on the circuit board, and make the setting state of the two boards to be exchanged completely consistent when changing boards, otherwise the system will be in an unstable or non-optimal state, or even give an alarm. ② After replacing some circuit boards (such as CCU boards), it is necessary to reset or input the parameters and programs of the grinder.

(7) Using detection terminals on the circuit board: There are detection terminals on the circuit board to measure the voltage and waveform of the circuit to determine whether this part of the circuit works normally during debugging and maintenance. But when testing this part of the circuit, you should be familiar with the circuit principle and the logical relationship of the circuit. If you are not familiar with the logical relationship, you can compare two identical circuit boards to find the fault of the circuit board.

In a word, once the CNC grinder fails, the maintenance personnel can correctly judge the cause and location of the failure according to the above detection steps and methods.