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The investigation and analysis of CNC vertical lathe faults is the first stage of troubleshooting and is a very critical stage. The following work should be done mainly:
1. Inquiry and investigation When receiving information about a machine tool on-site fault that requires troubleshooting, the operator should first be asked to try to maintain the on-site fault status without doing any processing. This will help to quickly and accurately analyze the cause of the fault. At the same time, carefully inquire about the fault indication, fault symptoms and the background of the fault, and make a preliminary judgment based on this to determine the tools, instruments, drawings, spare parts, etc. that should be carried for on-site troubleshooting to reduce round trip time.
2. After arriving at the site for on-site inspection, the accuracy and completeness of various conditions provided by the operator must first be verified to verify the accuracy of the initial judgment. Depending on the level of the operator, there are many cases where the description of the fault condition is unclear or even completely inaccurate. Therefore, after arriving at the scene, do not rush to deal with it, and re-investigate various situations carefully to avoid damaging the scene and making troubleshooting more difficult.
3. Fault analysis: Based on the known fault conditions, analyze the fault type according to the fault classification method mentioned in the previous section, so as to determine the troubleshooting principles. Since most faults are indicated, in general, multiple possible causes of the fault can be listed by comparing the CNC system diagnostic manual and operating instructions provided with the machine tool.
4. Determine the cause and investigate various possible causes to find out the real cause of the failure. This is a comprehensive test for the maintenance personnel's familiarity, knowledge level, practical experience and analysis and judgment ability of the machine tool.
5. Troubleshooting preparations. Some fault troubleshooting methods may be very simple, while other faults are often more complicated and require a series of preparations, such as the preparation of tools and instruments, partial disassembly, repair of parts, procurement of components, and even Formulation of troubleshooting plan steps, etc.
The process of investigation, analysis and diagnosis of faults in the electrical system of CNC vertical lathes is also the process of troubleshooting. Once the cause is identified, the fault is almost eliminated. Therefore, fault analysis and diagnosis methods have become very important. Commonly used diagnostic methods for electrical faults are summarized below.
1. Intuitive inspection method This method must be used at the beginning of fault analysis, which is to use sensory inspection.
Inquiry: Carefully ask the personnel at the fault site about the process, symptoms and consequences of the fault, and you may need to ask multiple times during the entire analysis and judgment process.
Visually check overall whether the working status of each part of the machine tool is in normal condition (such as the position of each coordinate axis, spindle status, tool magazine, manipulator position, etc.), and whether there are any electronic control devices (such as CNC system, temperature control device, lubrication device, etc.) Alarm indication, local inspection to see if the fuse is burnt, components are burned or cracked, wires and cables are falling off, whether the operating components are in the correct position, etc.
Touch: When the whole machine is powered off, you can detect possible faults by touching the installation status of each main circuit board, the plugging status of each plug socket, and the connection status of each power and signal wire (such as servo and motor contactor wiring). s reason.
Power-on refers to power-on to check whether there is smoke, sparks, abnormal sounds, smells, and whether there are overheated motors and components when touched. Once found, immediately cut off the power for analysis.
2. Instrument inspection method uses conventional electrical instruments
Measure the AC and DC power supply voltages of each group and the relevant DC and pulse signals to find possible faults. For example, use a multimeter to check the status of each power supply, and measure the relevant signal status measurement points set on some circuit boards. Use an oscilloscope to observe the amplitude, phase and even presence of relevant pulsation signals. Use a PLC programmer to find the PLC program. Fault location and cause, etc.
3. CNC vertical lathe signal and alarm indication analysis method
Hardware alarm indication refers to the various status and fault indicators on various electronic and electrical devices, including CNC systems and servo systems. Combining the indicator status and corresponding function descriptions, you can know the indication content, fault causes and troubleshooting methods. .
Software alarm indication As mentioned above, faults in system software, PLC programs and processing programs are usually equipped with alarm displays. According to the displayed alarm number, you can learn the possible cause of the fault and the troubleshooting method by referring to the corresponding diagnostic instruction manual.
4. Interface status checking method
Modern CNC systems mostly integrate PLC into them, and CNC and PLC communicate with each other in the form of a series of interface signals. Some faults are related to interface signal errors or losses. Some of these interface signals can be displayed with indicator lights on the corresponding interface boards and input/output boards. Some can be displayed on the CRT screen through simple operations, and all interface signals Signals can be called out using a PLC programmer. This inspection method requires maintenance personnel to be familiar with both the interface signals of the machine tool and the application of the PLC programmer.
5. Parameter adjustment method
The CNC vertical lathe CNC system, PLC and servo drive system all set many modifiable parameters to adapt to the requirements of different machine tools and different working conditions. These parameters not only match each electrical system to the specific machine tool, but are also necessary to optimize the functions of the machine tool.
Therefore, any parameter changes (especially analog parameters) or even loss are not allowed; and changes in mechanical or electrical performance caused by the long-term operation of the random machine will break the initial matching state and optimization state. This type of fault mostly refers to the latter type of fault in the fault classification section, and one or more related parameters need to be readjusted to eliminate it. This method has very high requirements for maintenance personnel. They must not only have a good understanding of the main parameters of the specific system, know its address and be familiar with its functions, but also have rich experience in electrical debugging.
6. Spare parts replacement method
When the fault analysis results are concentrated on a certain printed circuit board, it is very difficult to locate the fault in a certain area or even a certain component due to the continuous expansion of circuit integration. In order to shorten the downtime, it is very difficult to have the same If spare parts are available, you can replace the spare parts first, and then check and repair the faulty board. When replacing the spare parts board, pay attention to the following issues. Replacement of any spare parts must be done with power outage.
Many printed circuit boards have some switches or short-circuit bar settings to match actual needs. Therefore, when replacing the spare parts board, be sure to record the original switch positions and setting status, and make the same settings for the new board. must be set, otherwise an alarm will occur and the unit will not work. The replacement of some printed circuit boards also requires certain specific operations to complete the establishment of software and parameters after replacement. This requires careful reading of the instructions for use of the corresponding circuit board.
Some printed circuit boards cannot be easily pulled out, such as the board containing working memory or the backup battery board, which will lose useful parameters or programs. When replacement is necessary, instructions must also be followed. In view of the above conditions, before pulling out the old board and replacing it with a new one, be sure to read the relevant information carefully and understand the requirements and operating steps before proceeding to avoid causing greater failure.
7. Cross transposition method
When a faulty board is found or it is uncertain whether it is a faulty board and there are no spare parts, two identical or compatible boards in the system can be interchanged and checked, such as the exchange of two coordinate command boards or servo boards to determine the faulty board. or faulty part. Special attention should be paid to this cross-transposition method, not only the correct exchange of hardware wiring, but also the exchange of a series of corresponding parameters. Otherwise, not only will the purpose not be achieved, but new faults will occur and cause confusion in thinking. You must consider it thoroughly in advance. , design the software and hardware exchange plan, and then check the exchange if it is correct.
8.Special treatment method
Today's CNC vertical lathe CNC systems have entered a PC-based and open development stage. The software content is becoming more and more abundant, including system software, machine tool manufacturer software, and even the user's own software. Due to the limitations of software logic, Some inevitable problems in the design will make it impossible to analyze some fault conditions, such as crashes. For this kind of fault phenomenon, special measures can be taken to deal with it, such as powering off the whole machine, stopping for a while and then turning it on again. Sometimes the fault may be eliminated. Maintenance personnel can explore its rules or other effective methods in their long-term practice.