Fault analysis is the first step in maintenance. Equipment maintenance personnel should mainly start from the following aspects:
(1) What are the abnormalities in the investigation. Such as abnormal noise, motor overheating, malfunction, etc. The operator should try to keep the fault status of the equipment, such as the alarm information of the LCD screen, the display of the fault indicator, and the stop position of each component. (2) Initially determine the cause of the failure. Reverse the action or process of equipment failure that may be caused by the cause of the fault, and make a preliminary judgment on the cause of the fault. (3) Determine the repair procedure. Some faulty LCD screens or indicators will have code prompts. Check the equipment maintenance manual or the instruction manual to find out the possible causes of the fault, and then comprehensively analyze and check each one. (4) Some faulty machine tools may not have alarms, or the alarm information is wrong, especially for early-made machine tools. This requires maintenance personnel to have a deep understanding of the machine control system and practical experience. The essential reason.
There are many diagnostic methods for electrical faults in numerical control systems. In equipment maintenance, it is often necessary to comprehensively utilize various methods and check them one by one. The common diagnostic methods for electrical faults in CNC systems are as follows:
(1) Visual inspection This is the use of the sensory to conduct a preliminary analysis of the failure.
1 Look at whether the various parts of the machine tool are in a normal state (such as the position of each coordinate axis, spindle state, tool magazine, robot position, etc.), and whether there is an alarm indication for each electronic control device (such as CNC system, temperature control device, lubrication device, etc.) Check whether the fuse is burnt, the components are burnt, cracked, the wires and cables are disconnected, and the position of each operating component is correct or not. 2 Smell the odor to check whether the actuator, drive unit or control unit is overheated. 3 Ask the field personnel for the process of the fault, the condition or action of the equipment at the time of the fault. 4 Check whether the interface board and cable plug are loose, whether the temperature of the equipment is high, and whether the air cooling effect of the cooling fan is normal.
(2) Instrument inspection. Use inspection instruments such as multimeters, oscilloscopes, infrared thermometers, etc. to check the power supply, motor windings and signal lines, and measure and analyze the relevant DC and pulse signals, and the temperature of the equipment components.
(3) Signal and alarm indication analysis method 1 Software alarm When the fault occurs, the CNC system will display the corresponding alarm information or fault code on the LCD screen on the operation panel by detecting and judging. The maintenance personnel can also infer the cause of the failure by checking the execution status of the relevant element through the plc program. 2 Hardware alarm CNC system, servo system and some main electronic circuit boards generally have a set of LED indicators that reflect the state of the hardware. According to the combination status of the indicators and the corresponding equipment manual, the hardware fault content and the cause of the fault can be easily obtained. Method of exclusion. 3 Spare parts replacement When the fault analysis results are concentrated on a printed circuit board, due to the high degree of circuit integration, in order to reduce the downtime, the spare parts can be replaced before the same spare parts, and then the repair fault is checked. board. 4 Cross-transposition method can replace two components or boards that are similar or compatible in the system without spare parts or parts disassembly inspection, such as X\Y\Z servo motor failure, X, Y The fault of the command board or the servo board of the coordinate can be judged by the exchange troubleshooting method. Special attention should be paid to the application of this transposition method. It is necessary not only to determine the correct insertion of the hardware wiring, but also to set a series of jumper switches or parameters in the correct state, otherwise it may cause new troubles. 5 Parameter adjustment CNC system, PLC and servo drive system At the initial stage of installation and commissioning of equipment manufacturers, (learned from http://), some parameters were adjusted according to the electrical and mechanical properties of the machine at that time. Meet the processing requirements of machine tools. These parameters optimize the overall machining of the machine. However, with the change of mechanical or electrical performance caused by the long-term operation of the machine tool, the initial parameter setting is no longer suitable for the working performance of the machine tool, so it is necessary to re-adjust the relevant parameters for optimization. 6 Interface status check Modern CNC system integrates PLC in it, and CNC and PLC communicate with each other in a series of interface signals. Some faults are related to the transmission error or loss of I/O interface signals. Some of these interface signals can be displayed on the corresponding interface board and I/O board, and some can be displayed on the CRT screen by simple operation. And all interface signals can be called up with the plc programmer. 7 Special Processing Methods Today's CNC systems have entered the development stage of PC-based and open-ended. The software content is becoming more and more abundant. Sometimes internal conflicts may occur in the design of software logic, resulting in system errors, such as crashes. This kind of fault phenomenon can be handled by special means. For example, the whole machine is powered off, and then restarted after a pause, the fault will be automatically eliminated.
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