The demand of CNC machine tools is increasing, and CNC machine tools can efficiently solve the production of parts, making the production of parts more efficient and more accurate. Therefore, the demand for CNC machine tools is also increasing. Therefore, it is urgent to improve the production efficiency of CNC machine tools. Therefore, the requirements of fault diagnosis of CNC machine tools should be strengthened in order to improve the quality of CNC machine tools. Therefore, this paper studies and applies the diagnosis method and process of NC machine tool mechanical fault.
1. External and internal
After the fault occurs, the whole body inspection from inside to outside is carried out by using the method of "looking, listening and inquiring", such as the damage of various switch parts, connecting parts, sensor sensitivity, temperature and humidity, oil mist, etc. on the components and circuit board.
2. Mechanical before electrical
Mechanical fault is easy to be detected, so start with simple mechanical fault, and the difficulty coefficient of fault diagnosis of CNC system is relatively large, what's more, some electrical faults are caused by mechanical faults. Therefore, the waste of labor can be reduced by first mechanical and then electrical.
3. Static before moving
Due to the high precision and complexity of CNC machine tools, it may cause a lot of losses if it is repaired without fault diagnosis. Therefore, before fault diagnosis, don't do it blindly. You should understand the process and status of the fault when it occurs, consult the relevant information, analyze the possible causes of the fault, and then make fault diagnosis.
4. Public use first and then private use
Public problems often affect the overall situation. If several feed shafts do not move, first check the power supply, CNC, PLC, and hydraulic and other common parts.
5. Simple before complex
When a variety of fault problems interweave with each other and it is difficult to solve the problem, the easy fault can be solved first, and the problem may become simple.
6. General before special
When troubleshooting a fault, the most common and possible causes should be considered first, and then the special causes that rarely occur should be considered and analyzed.
In CNC machine tools, most of the faults can be checked for maintenance, but there are also some faults, because the warning information provided by them is vague and unable to send out an alarm, or the time is short, irregular and irregular, which leads to failure analysis. Therefore, it is required to classify the faults accurately to facilitate the progress of maintenance.
7. Fault classification of CNC machine tools
1. Classification according to the nature of CNC machine failure
(1) Deterministic fault: as long as the conditions are met, there will be a fault; for example, if the voltage load is too high, the alarm will be given.
(2) Random fault: it refers to that under the same conditions, the alarm signal will be sent out once or twice randomly; this kind of fault is the most difficult to analyze and investigate; this kind of fault is generally associated with mechanical structure parts and CNC system parts.
2. Classification by fault type
(1) Mechanical fault: it mainly occurs in the host part of the machine tool. The common faults mainly include: mechanical transmission failure caused by nonstandard installation, debugging and operation of mechanical components; failure caused by interference and excessive friction of moving parts such as guide rail and spindle; failure caused by damage of mechanical parts; poor connection, etc.
(2) Electrical fault: refers to the failure of electrical control system. Common faults mainly include: weak current fault caused by electronic components and integrated circuit of control system; strong current fault caused by relay, contactor, switch, fuse, power supply voltage device and other electrical components and devices in main circuit or high-voltage and high-power circuit of control system and the control circuit composed of them.
8. CNC machine tool mechanical fault diagnosis method
(1) Tracing method: before fault diagnosis and maintenance, the maintenance personnel should have a detailed understanding of the time when the fault occurred, the operating condition of the machine tool and the fault type, and then look for the traces of the failure.
(2) Self diagnosis function: it means that the internal diagnostic program of the CNC system will automatically execute the diagnosis every time it is powered on. By monitoring the working condition of each part of the system at any time, analyze the fault in time and display the alarm information on CRT immediately. Sometimes when hardware failure occurs, diodes are used to point out the cause of the failure. If the start-up diagnosis can not be finished, the system can not be put into production.
(3) Online diagnosis: refers to the automatic diagnosis and inspection of CNC system itself, each unit connected with CNC device and external equipment through the built-in program of CNC system when the system is in normal operation state. As long as the system is not powered off, online diagnosis will continue.
(4) Off line diagnosis: after the exponential control system fails, CNC system manufacturers, experts, or professional maintenance centers use special diagnostic software and test devices to stop or offline check.
9. General process of mechanical fault diagnosis of CNC machine tools
(1) Observe the situation of CNC machine tool: observe the fault through the method of "look, hear, ask and understand".
(2) Fault analysis: through observing the fault situation to carry out the situation analysis, so as to narrow the fault range and determine the fault search method.
(3) Fault finding: the use of search means for CNC machine tools from the outside to the inside, from easy to difficult detection, access to relevant information to determine the fault point.
On 2018-08-08 11:45:46
