CNC machine tool repair and troubleshooting technology
Computer Embroidery Machine,Multi Heads Embroidery Machine,Flat Embroidery Machine HEFENG COMPUTERIZED EMBROIDERY MACHINES LIMITED , http://www.hk-embroiderymachine.com
(1) The hardware and software faults can be classified as faults. Hardware failure refers to the abnormal state or even damage of electronics, electrical devices, printed circuit boards, wires and cables, connectors, etc. This is a failure that can be eliminated if it needs to be repaired or even replaced. The software fault generally refers to the fault generated in the plc logic control program, and it is necessary to input or modify some data or even modify the plc program to eliminate the fault. Faults in part processing programs are also software faults. The most serious software failure is the defect or even the loss of CNC software. This can only be solved by contacting the manufacturer or its service organization.
(2) When there is an indication when the fault occurs, it is divided into a diagnostic indication failure and a non-diagnosis indication failure. Today's CNC systems are designed with a perfect self-diagnostics program. When monitoring the software and hardware performance of the entire system, they will immediately report an alarm or a brief textual description on the screen. You can find the cause, location, and tips for troubleshooting. Machine tool builders will also design relevant fault indications and diagnostic instructions for specific machine tools. The faults indicated in the above two parts with diagnostic indications plus various types of indicators on various electrical devices make it easier to eliminate most electrical faults. Part of the failure without diagnostic indication is caused by the incompleteness of the above two diagnostic procedures (eg, the switch is not closed, the connector is loose, etc.). Such failures must rely on the work process and fault phenomena and consequences before the failure, and rely on maintenance personnel to analyze and eliminate the familiarity and technical level of the machine tool.
(3) Whether there is destructiveness in the event of failure or not, it is divided into destructive failure and non-destructive failure. For a destructive failure, damage to the workpiece or even the failure of the machine tool is not allowed to be repeated during maintenance. At this time, the inspection and analysis can be performed according to the phenomenon when the fault occurs. The 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 fault process, but be very careful.
(4) With the probability of failure, it is divided into systematic failure and random failure. Systematic fault refers to certain faults that must be generated as long as certain conditions are satisfied. Random faults are faults that occasionally occur under the same conditions. The analysis of such faults is more difficult and usually involves more mechanical structures. Partial looseness and misalignment, drifting or degraded reliability of some electrical workpieces, and high internal temperature of electrical devices. The analysis of such failures can be eliminated only after repeated tests and comprehensive judgments.
(5) Measured by the machine's movement quality characteristics, it is the failure of the machine's movement characteristics. In this case, the machine tool works normally but fails to produce qualified parts. For example, the positioning accuracy of the machine tool is poor, the reverse dead zone is too large, and the coordinate operation is not smooth. This type of fault must be detected by the use of testing instruments to diagnose the machine and the electrical link, and then eliminated by optimizing the mechanical transmission system, numerical control system and servo system.
The classification of faults here is to facilitate the analysis and elimination of faults, and the generation of a fault is often a mixture of multiple types. This requires the maintenance personnel to analyze it in detail and refer to the above classification to take corresponding analysis and elimination methods.
2. Investigation and Analysis of Failures This is the first stage of troubleshooting, and it is a very critical stage. The following tasks should be done:
1 Inquiring about the survey When receiving the information that the failure of the machine tool site is required to be eliminated, the operator should first be required to maintain the on-site fault status as far as possible, without any treatment, which is conducive to quickly and accurately analyzing the cause of the fault. At the same time, carefully inquire about fault indication conditions, fault appearances, and background conditions of faults, and make preliminary judgments in order to determine tools, meters, drawing materials, spare parts, etc. that should be carried on site to reduce the round trip time.
2 After the on-site inspection arrives at the site, it is first necessary to verify the accuracy and completeness of various conditions provided by the operator, so as to verify the accuracy of the preliminary judgment. Due to the operator's level, there are no lack of examples of unclear or even inaccurate descriptions of fault conditions. Therefore, do not rush to handle the situation after the scene. Re-investigate all kinds of situations carefully so as not to damage the site and increase the difficulty of troubleshooting.
3 Fault Analysis According to the known fault conditions, the fault classification method is used to analyze the fault types as described in the previous section to determine the troubleshooting principle. Since most of the faults are indicated, under normal circumstances, many possible causes of the fault can be listed in comparison with the CNC system diagnostics manuals and operating instructions that accompany the machine tool.
4 Determining the Cause The investigation of various possible causes leads to the real cause of the failure. At this time, the maintenance personnel is a comprehensive test of the familiarity, knowledge level, practical experience, and analytical judgment ability of the machine tool.
5 troubleshooting troubleshooting may be very simple, and some failures are often more complex, need to do a series of preparations, such as the preparation of instrumentation, partial disassembly, repair of components, procurement of components and even row Therefore, the development of planning steps and so on.
The process of investigation, analysis, and diagnosis of the faults in the electrical system of CNC machine tools is also the troubleshooting process. Once the cause is identified, the fault is almost equal to the elimination. Therefore, the method of fault diagnosis and diagnosis becomes very important. Below is a list of common diagnostic methods for electrical faults.
(1) Visual inspection This is the method that must be used at the beginning of the fault analysis. It is to use sensory inspections.
1 Ask to ask the fault site personnel to carefully inquire about the fault occurrence process, fault appearance, and fault consequences, and may ask for multiple inquiries during the entire analysis and judgment process.
2 Visually check whether the working status of each part of the machine tool is in a normal state (such as the position of each coordinate axis, spindle status, magazine, robot position, etc.). Each electronic control device (such as numerical control system, temperature control device, lubrication device, etc.) has No alarm indication, partial inspection with or without insurance calcined, components burned, cracking, wire and cable drop, the correct position of the operating elements and so on.
3Touching can be found under the condition of power failure of the whole machine by touching the installation status of each main circuit board, the plugging status of each plug connector, and the connection status of each power and signal wire (such as servo and motor contactor wiring). The cause of the failure.
4 Power On This is to check whether there is smoke, ignition, presence of abnormal sound, odor, and presence of overheated motors and components.
(2) Instrument inspection method Use conventional electrical instruments to measure the AC and DC power supply voltages of each group and measure the relevant DC and pulse signals to find possible faults. For example, use a multimeter to check the power supply conditions, and measure the relevant signal state measurement points set on some circuit boards. Use an oscilloscope to observe the amplitude and phase of the related pulsating signals. Use the plc programmer to find the plc program. Fault location and causes.
(3)Signal and alarm indication analysis method 1 Hardware alarm indication This refers to various status and fault indicators on various electronic and electrical devices, including the numerical control system and servo system, combined with indicator status and corresponding function description. You can learn about the content of the instruction, the cause of the failure, and how to remove it.
2 Software alarm indication As mentioned above, the faults in the system software, plc program and processing program are usually equipped with alarm display. According to the displayed alarm number, the corresponding diagnosis instruction manual can be used to know the possible fault causes and troubleshooting methods.
(4) Checking the interface state The modern numerical control system integrates plc in it, and the cnc and plc communicate with each other through a series of interface signals. Some faults are related to the signal error or loss of the interface. Some of these interface signals can be displayed on the corresponding interface board and input/output board, and some can be displayed on the crt screen through simple operations. All interfaces Signals can be called using the plc programmer. This inspection method requires maintenance personnel to be both familiar with the machine interface signal, but also familiar with the plc programmer application.
(5) Parameter adjustment method The numerical control system, plc and servo drive system all set many modifiable parameters to meet the requirements of different machine tools and different working conditions. These parameters not only enable the electrical systems to match the specific machine tools, but they are also necessary to optimize the machine tool functions. Therefore, any change of parameters (especially the analog parameters) or even the loss is not allowed; and the mechanical or electrical performance changes caused by the long-term operation of the random bed will break the initial matching state and the optimization state. This kind of fault refers to the latter type of fault in the fault classification section. It is necessary to readjust the relevant one or more parameters before troubleshooting. This kind of method is very high to the maintenance personnel's request, not only must understand the main parameter of the specific system very well, knows its address to be familiar with its function, moreover must have the rich electric debugging experience.
(6) Spare part replacement method When the fault analysis result is concentrated on a certain printed circuit board, it is very difficult to implement the fault on an area or even a certain component due to the continuous expansion of the circuit integration degree. During the downtime, the spare parts can be replaced with the same spare parts, and then the failed board can be checked and repaired. Replace the spare board with the following issues.
1 Replacement of any spare parts must be done in the event of a power failure.
2 Many printed circuit boards have some switch or shorting bar settings to match the actual needs, so be sure to record the original switch position and setting status on the replacement spare board and make the new board the same Set, otherwise an alarm will be generated and it will not work.
3 Some printed circuit board replacements also require certain operations after the replacement to complete the establishment of software and parameters therein. This requires careful reading of the corresponding board's instructions for use.
4 Some printed circuit boards cannot be easily removed, such as a board containing a working memory, or a spare battery board, which loses useful parameters or programs. When must be replaced, follow the instructions.
In view of the above conditions, be sure to carefully read the relevant information before you remove the old board and replace it with a new board, understand the requirements and operating procedures before you start, so as to avoid causing a greater failure.
(7) Cross-crossing method When the fault board is found or the fault board cannot be determined and there is no spare part, the same or compatible two boards in the system can be checked interchangeably, for example, two coordinate command boards or servos The exchange of the board determines the fault board or fault location. This crossover 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 new failures caused confusion of thinking, must be fully considered in advance , design a good software and hardware exchange program, accurate and then exchange inspection.
(8) Special handling methods Today's CNC systems have entered the PC-based and open development stage, in which the software content is more and more abundant, there are system software, machine tool builder software, and even the user's own software, due to the software logic Some problems that are unavoidable in the design will make it impossible to analyze some of the fault conditions, such as crashes. For this kind of failure phenomenon, special measures can be taken to deal with it, such as the power failure of the whole machine, restart after a pause, and sometimes the failure may be eliminated. Maintenance personnel can explore their laws or other effective methods in their own long-term practice.