Common faults and their classification of CNC machine tools
CNC machine tools and classification of common faults1 site of fault classification by
⑴ host host failure CNC CNC machine tools usually refers to the mechanical components, lubrication, cooling, chip removal, hydraulic, pneumatic and protection and other parts. Host common faults are:
1) due to mechanical parts installation, commissioning, operation causes such as improper use of mechanical drive failure
2) the rail, spindles and other moving parts of the interference, excessive friction causes such as failure
3) damage due to mechanical parts, link failure causes such as poor, and so on.
Host failure mainly to transmission noise, and processing accuracy, running resistance, mechanical parts without action, damage, and so on mechanical components. Poor lubrication, hydraulic, pneumatic and sealing system piping blockage bad, is a common cause of failure of the host. Regular maintenance of CNC machine tools, maintenance. Control and eradication of the "three-drain" phenomenon is to reduce the host part of the failure of important measures.
⑵ electrical control system failure from the type of components used. According to common practice, the electrical control system failures are usually classified as "weak" fault and "strong power" failure two categories,
"Weak" part refers to the control system, electronic components, integrated circuits based control part. The weak part of the CNC machine tools including CNC, PLC, MDI / C RT and the servo drive unit, the input to the output unit and so on.
"Weak," failure have a hardware failure and software failure of the points. Hardware failure is the various parts of the integrated circuit chip, discrete electronic components, connectors and other components of the external connection failures. Hardware, software failure is the normal situation in the action arising from errors, data loss and other failures are common. Processing errors, system procedures and parameters change or loss of computing error and so on.
"Strong power" part refers to the control system in the main circuit or high voltage, high power circuit of relays, contactors, switches, fuses, power transformers, motors, solenoids, limit switches and other electrical components and its components the control circuit. Although this part of the fault repair, diagnosis is more convenient, but because it is in the high-voltage, high current work status, probability of failure is higher than the "weak" part. Must draw enough attention to maintenance personnel.
2. Classified according to the nature of failure
⑴ deterministic fault deterministic control system failure is the host of hardware damage or as long as certain conditions are met, the failure will happen CNC machine tools. Phenomenon of this type of failure is most common in CNC machine tools, but because it has certain rules, and therefore to bring the convenience of maintenance
Uncertainty has unrecoverable failure, failure in the event, if not its maintenance process, machine does not automatically return to normal. But as long as the root cause of the failure to identify and repair the machine immediately after return to normal. Proper use and careful maintenance is to eliminate or avoid failure of the important measures.
⑵ random failure random failures are index-controlled machine tools in the course of occasional failures of such failure causes more subtle, difficult to find its regularity, Guchang called "soft failure", the causes of random analysis and fault diagnosis is difficult, in general, the incidence of failure is often associated with the installation of quality components, parameter setting, the quality of components, software design is imperfect, the working environment and many other factors.
Random failures are recoverable, failures occurred, through measures such as rebooting the machine usually return to normal, but in the running, but the same failure may occur.
Strengthen the NC system maintenance checks to ensure that the electrical box sealing, reliable installation, connection, grounding and shielding is to reduce and prevent such failure of the important measures.
3. According to the instructions of the form of fault classification
⑴ have reported failure of CNC machine tools with the display shows the fault can be divided into light and the display shows two cases:
1) LED alarm indicator alarm is through the control system status indicator on the unit (usually by a small LED indicator light tube or component) displayed alarm. According to CNC system status indicators, even if the monitor fails, the analysis can roughly determine the location and nature of the fault, so. In the maintenance, troubleshooting process should be carefully checked the status of these status indicators.
2) The display shows the alarm. Display shows the alarm display is displayed by CNC alarm number and alarm information to the police. As the numerical control system generally have a strong self-diagnostic function, if the system's diagnostic software and display circuit is working properly, if the system fails, you can display the alarm number and the text displayed fault information. NC alarm system can be displayed anywhere from dozens to more than a thousand, it is important troubleshooting information.
The display shows the alarm, the alarm can be divided into NC and PLC report and other categories. The former set of CNC manufacturers fault display. It can control the system of "maintenance manual" to determine the possible cause of the failure. The latter is set by the CNC machine tool manufacturer information on the PLC alarm texts, belonging to the machine side of the fault display. It can control machine tool manufacturers to provide "machine maintenance manual" in the relevant content. Determine the causes of failures.
⑵ no fault of such failure alarm occurs. Machine with no alarm system, the difficulty of analysis and diagnosis are usually larger. Through careful, careful analysis to determine the order to be recognized. Especially for some of the early numerical control system, because the system itself is not strong diagnostic capabilities, with or without PLC alarm texts, there was no alarm failure situation I wish you more.
For no alarm failure, usually specific conditions, according to the fault occurred before and after the change. Analysis to determine, theory analysis and analysis of the PLC program is to solve the fault-free alarm display the main method.
4. Classification according to the causes of failure
⑴ own CNC machine failure is due to the occurrence of such failures of CNC machine tools caused their own reasons, nothing to do with the external use of environmental conditions. CNC machine tool failure occurred in the vast majority are such failures.
⑵ CNC machine tools such failure is due to external faults caused by external reasons. Supply voltage is too low, too high, volatility is too large: power supply phase sequence is incorrect or unbalanced three-phase input voltage; ambient temperature is too high: harmful gases, moisture, dust granted into: foreign interference is caused by vibration and failure of reasons.
In addition, human factors also contributed to the failure of the external CNC machine one of the reasons, according to the statistics, the first use of CNC machine tools or by non-skilled workers to operate CNC machine tools, in the first year of use, improper operation caused by external fault to machine tools accounted for more than one third of total failure.
In addition to the common method of fault classification, there are various other classification methods. Such as: whether the failure occurs by destructive. Failure can be divided into destructive and non-destructive fault two. Failure and need of repair according to the specific function of position. Can be divided into numerical control device failure, feed servo system failure, the spindle drive system failure, automatic tool change system failure, etc., this classification method used in the repair.
Tai'an City Machine Manufacturing Co., Ltd. Hite Technology Center feeds
July 30, 2010