The method of avoiding the burning phenomenon of bus processing machine
- Time of issue:2013-04-01 00:00
The method of avoiding the burning phenomenon of bus processing machine
- Time of issue:2013-04-01 00:00
1.Bus processing machineCommon electrical fault classification
The electrical fault of CNC bus processing machine can be classified according to the nature, appearance, cause or consequence of the fault.
(1) According to the location of the fault, it can be divided into hardware fault and software fault. Hardware fault refers to the abnormal state or even damage of electronics, electrical parts, printed circuit boards, wires and cables, connectors, etc., which need to be repaired or even replaced to eliminate the fault. And software fault is to point to PLC logic control procedure in general the fault that produces, need to input or modify some data even modify PLC procedure can eliminate the fault. Part processing program fault also belongs to software fault. The most serious software failure is the nc system software defect or even loss, which can only be solved by contacting the manufacturer or its service organization.
(2) According to the occurrence of faults without indication, it can be divided into faults with diagnostic indication and faults without diagnosis indication. Today's numerical control system is designed with perfect self diagnostic procedures, when the real monitoring software and hardware of the whole system performance, once found will immediately report to the police or fault and brief text displayed on the screen, combining system equipped with diagnostic manual can not only find the cause of the failure and parts, but also eliminate the method. Machine tool manufacturers will also design specific machine tool failure instructions and diagnostic instructions. The above two parts of the diagnostic indication of the fault together with the various types of lights on the electrical device makes the troubleshooting of most electrical faults easier. The failure without diagnostic indication is partly due to the incompleteness of the above two diagnostic procedures (e.g. switch not closed, loose plug, etc.). This kind of failure depends on the working process and fault phenomenon and consequences before the failure, and relies on maintenance personnel to analyze and eliminate the familiarity and technical level of machine tools.
(3) If there is no destructive failure when the fault occurs, it can be divided into destructive failure and non-destructive failure. For destructive failure, damage to the workpiece or even the fault of the machine tool, maintenance is not allowed to repeat, then only according to the phenomenon of the failure of the corresponding inspection, analysis to eliminate it, technical difficulty is high and there is a certain risk. If it is possible to damage the workpiece, remove the workpiece and try to reproduce the failure process, but with great care.
(4) According to the probability of failure, it can be divided into systematic failure and random failure. Systematic fault refers to the definite fault which will occur as long as certain conditions are met. The random fault refers to the occasional failure under the same conditions, the analysis of this kind of fault is more difficult, usually with the machine tool mechanical structure of local loose dislocation, part of the electrical workpiece characteristic drift or reliability reduction, electrical device internal temperature is too high. The analysis of this kind of fault can be eliminated only after repeated test and comprehensive judgment. (5) measured by the motion quality characteristics of CNC machining machine tool, it is the fault that the motion characteristics of machine tool decline. In this case, the machine tool can work normally but not produce qualified workpiece. For example, the positioning accuracy of machine tools is out of tolerance, the reverse dead zone is too large, and the coordinate operation is not stable. This type of fault must be identified by the use of testing instruments to produce errors in the mechanical and electrical links, and then through the mechanical drive system, numerical control system and servo system optimization adjustment to eliminate.
2.Bus processing machineFailure investigation and analysis
This is the first stage of troubleshooting, which is very critical. The following work should be done:
① Inquiry investigation in receiving the machine tool site fault troubleshooting information, the operator should first try to maintain the site fault state, do not do any processing, which is conducive to rapid and accurate analysis of the cause of the fault. At the same time, carefully inquire the fault indication, fault appearance and the background of the fault, and make a preliminary judgment according to this, so as to determine the tools, meters, drawings, spare parts, etc. that should be carried for on-site troubleshooting, and reduce the round-trip time.
② After the on-site inspection arrives at the scene, the accuracy and completeness of various situations provided by the operator should be verified first, so as to verify the accuracy of the preliminary judgment. Due to the level of the operator, the failure of the description of the situation is not clear or even completely inaccurate case, so to the scene still do not rush to start processing, carefully investigate the situation again, so as not to destroy the scene, so that the difficulty of troubleshooting increased.
③ Fault analysis According to the known fault conditions according to the fault classification method described in the previous section to analyze the fault type, so as to determine the troubleshooting principle. Since most faults are indicated, in general, a variety of possible causes of the fault can be listed in the diagnostic manual and operation manual of the CNC system supporting the machine tool.
④Determine the cause of a variety of possible causes to find out the true cause of the fault, then the maintenance personnel is a comprehensive test of the machine tool familiarity, knowledge level, practical experience and analysis and judgment ability.
⑤ Troubleshooting preparation Some troubleshooting methods may be very simple, some faults are often more complex, need to do a series of preparatory work, such as the preparation of tools and meters, partial disassembly, parts and components repair, the procurement of components and even the formulation of troubleshooting planning steps and so on. The process of fault investigation, analysis and diagnosis of CNC machine tool electrical system is the process of fault elimination. Once the cause is found out, the fault is almost eliminated. Therefore, the method of fault analysis and diagnosis becomes very important. Common diagnostic methods for electrical faults are summarized below.
(1) Intuitive inspection method, which is the initial method of fault analysis must be used, is to use sensory inspection. (1) Ask the fault site personnel to carefully ask the process of the fault, the appearance of the fault and the consequences of the fault, and in the whole process of analysis and judgment may be asked for many times. (2) the overall visual check to see if machine parts working status in normal condition (such as the axis, state of spindle, tool storage, manipulator position, etc.), the electronic control unit (such as numerical control system, temperature control device, lubrication device, etc.) with or without alarm indication, partial view burn calcined with and without insurance, components burnt fall off, craze, wire and cable, The correct position of each operating element and so on. (3) Touch In the condition of power off the whole machine, you can find the possible cause of failure by touching the installation status of the main circuit board, the insertion status of the plug seat, the connection status of the power and signal wires (such as servo and motor contactor wiring). (4) Power this is to check whether there is smoke, fire, abnormal sound, smell and touch whether there is overheating motor and components exist and power, once found immediately power off analysis.
(2) The instrument inspection method uses conventional electrical instruments to measure the ac and DC power supply voltage of each group and the relevant DC and pulse signals to find possible faults. For example, use a multimeter to check each power supply situation, and the measurement point of the relevant signal state set on some circuit board, observe the amplitude and phase of the relevant pulsating signal with oscilloscope, and even have it, use PLC programmer to find the fault position and reason in THE PLC program.
(3) signal and alarm indicator analysis method ① Hardware alarm indicator this refers to the various states and fault indicators on electronic and electrical devices, including NUMERICAL control system, servo system, combined with the indicator state and the corresponding function description can be informed of the indication content and fault causes and troubleshooting methods. (2) Software alarm instructions as mentioned before in the system software, PLC program and processing procedures are usually equipped with alarm display, according to the alarm number displayed against the corresponding diagnostic manual can be informed of the possible cause of failure and troubleshooting methods.
(4) Interface state inspection method modern CNC system will be more integrated in PLC, and between CNC and PLC in a series of interface signal form of mutual communication connection. Some faults are related to the error or loss of interface signals. Some of these interface signals can be displayed on the corresponding interface board and input/output board with indicator light, and some can be displayed on the CRT screen through simple operation, and all interface signals can be called out by PLC programmer. This inspection method requires maintenance personnel to be familiar with both the interface signal of the machine tool and the application of PLC programmer.
(5) Parameter adjustment numerical control system, PLC and servo drive system set many parameters can be modified to adapt to the requirements of different machine tools, different working conditions. These parameters are not only necessary to match the electrical system with the machine tool, but also necessary to optimize the functions of the machine tool. Therefore, any parameter change (especially analog parameter) or even loss is not allowed; Changes in mechanical or electrical properties caused by long-term operation of the machine will break the initial matching state and optimization state. This type of fault refers to the later type of fault in the fault classification section. You need to adjust one or more related parameters to rectify the fault. This method of maintenance personnel is very high requirements, not only to the specific system of the main parameters very understanding, both know its address familiar with its role, but also to have rich experience in electrical commissioning.
(6) spare parts replacement When failure analysis results focused on a printed circuit board, due to the constant expansion of the circuit integration and to the failure to implement on it an area and even a certain element is very difficult, in order to shorten the down time, in the same conditions of spare parts can spare parts replaced first, and then to check repair the failure board. Note the following when replacing the spare board. Replacement of any spare parts must be done without power. Many printed circuit boards have some switches or short circuit bar Settings to match the actual needs, so in the replacement of spare parts board must record the original switch position and setting state, and the new board to do the same setting, otherwise it will generate an alarm and can not work. Some printed circuit boards need to be replaced after the replacement of some specific operations to complete the establishment of software and parameters. This requires careful reading of the circuit board instructions. Some printed circuit boards cannot be easily removed, such as a board containing working memory, or a backup panel, which will lose useful parameters or programs. If replacement is necessary, it must follow the relevant instructions. In view of the above conditions, before removing an old board and replacing it with a new one, read the relevant materials carefully and understand the requirements and operation procedures before starting to avoid greater faults.
(7) Cross transposition method When the fault board is found or the fault board cannot be determined and there are no spare parts, the same or compatible two boards in the system can be exchanged for inspection, such as the exchange of two coordinate command boards or servo boards to determine the fault board or fault location. This cross transposition method should pay special attention to, not only the correct exchange of hardware wiring, but also a series of corresponding parameters exchange, otherwise not only fail to achieve the purpose, but will produce a new fault caused by confusion of thinking, we must consider thoroughly in advance, design a good software and hardware exchange scheme, accurate exchange check.
(8) special processing method Today's numerical control system has entered the stage of development of PC base, open, the increasingly rich content of software, system software, software of machine tool manufacturers, users and even their own software, as a result of the design of software logic, some inevitable problems in makes some fault state cannot analysis, such as the freezing. For this fault phenomenon can take special measures to deal with, such as power off the whole machine, a pause and then turn on, sometimes the fault may be eliminated. Maintenance personnel can explore its rules or other effective methods in their long-term practice.
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