CNC machine tool is an efficient automatic machine tool. It combines new technical achievements in various fields such as computer technology, automation technology, servo drive, precision measurement and precision machinery. It is an emerging industrial control technology. Due to its good economic performance and high production efficiency, it is in an increasingly important position in production. In order to improve the utilization rate of the machine tool and improve the efficiency of the system, the general method of fault handling and maintenance of the CNC system is discussed in light of the actual work. To improve the maintenance technology of CNC machine tools.
I. Intuitive method <br> The maintenance personnel carefully observe the various parts of the system through the observation of various abnormal phenomena such as light, sound and taste during the failure, and reduce the fault range to a module or a printed circuit board.
Example 1: During the machining of CNC machine tools, sudden shutdown occurs. Open the CNC cabinet and check that the main circuit fuse of the Y-axis motor burned out. After careful observation, check the parts related to the Y-axis. Finally, the power line of the Y-axis motor was scratched by a hard object, and the damage hit the machine casing, causing damage. Short-circuit burnout insurance, after replacing the Y-axis motor power line, the fault is eliminated and the machine tool returns to normal.
Second, the self-diagnosis function method <br> The self-diagnosis function of the numerical control system has become an important indicator to measure the performance characteristics of the numerical control system. The self-diagnosis function of the numerical control system monitors the working state of the numerical control system at any time. In the event of an abnormality, immediately display an alarm message on the CRT or use LEDs to indicate the general cause of the fault, which is the most effective method of repair.
Example 2: AX15Z CNC lathe, equipped with FANUC1 0TE-F system, fault display:
FS10TE 1399B
ROM TEST: END
RAM TEST:
The display of the CRT indicates that the ROM test passed and the RAM test failed. The RAM test failed, not necessarily the RAM failure. It may be that the parameters in the RAM are lost or the battery contact is poor. The reason for the fault is that the battery is poorly contacted after replacing the battery, so the above failure phenomenon occurs when the battery is turned on.
Third, the function program test method
The function program test method is to program the common functions and special functions of the numerical control system into a functional test program by manual programming or automatic programming, and send it to the numerical control system, and then let the numerical control system run the test program to check the machine tool to perform these functions. Accuracy and reliability, and then determine the possible cause of the failure.
Example 3: Using a numerical control milling machine of FANUC 6M system, the crawling phenomenon occurs when the workpiece is subjected to curve processing. With the self-programming function test program, the machine tool can smoothly run various predetermined actions, indicating that the machine numerical control system works normally, so Checking the curve processing program used, it is found that the G61 command is used during programming, that is, the machining is performed once to the end of the machining, so that the machine tool is crawling, and the G61 command is changed to the G64 (continuous cutting mode) command. After the replacement, the crawling phenomenon is eliminated.
IV. Exchange Method <br> The so-called exchange method is to replace the suspected part with a spare printed circuit board, template, integrated circuit chip or component in the case of analyzing the general cause of the failure, thereby narrowing the fault range to the printed circuit board. Or chip level.
Example 4: The TH63 50 machining center rotary table is rotated after lifting, and there is no deceleration, and no alarm signal appears. For such a fault, it may be caused by a simple position controller failure of the rotating workpiece table. To further confirm the fault location, it is considered that the simple position controller of the tool magazine of the machining center is basically the same as the turntable. Then, the exchange method is used to check, the position controller of the tool magazine and the turntable is exchanged, and the tool position controller is reset according to the setting of the turntable position controller. After the exchange, the tool magazine is rotated, and the tool magazine is rotated. The turntable was operating normally, confirming that the fault was indeed on the position controller of the turntable.
V. Principle analysis method <br> According to the principle of CNC composition, the logic level and characteristic parameters of each point are logically analyzed, and the analysis and judgment of the working parts of the system are carried out to determine the maintenance method of the fault part. The application of this method requires maintenance personnel to have a clear and deep understanding of the working principle of the entire system or each component, so that the fault location can be located.
Example 5: The PNE71 0 CNC lathe has a Y-axis feed out of control. Whether it is jog or program feed, the rail can't stop once it moves, until the emergency stop is pressed.
According to the basic principle of the position control of the numerical control system, it can be determined that the fault is on the position loop of the X-axis, and it is likely that the position feedback signal is lost. Thus, once the numerical control device gives the command position of the feed amount, the actual position of the feedback is always Zero, the position error can not be eliminated at all times, resulting in the loss of control of the machine feed. The pulse encoder of the position measuring device is removed for inspection. It is found that the filament in the encoder is broken, resulting in no feedback input signal. After replacing the Y-axis encoder, the fault is eliminated.
Sixth, parameter inspection method
When the CNC system finds a fault, it should check the system parameters in time. The change of the system parameters will directly affect the performance of the machine tool, and even the machine tool can not work normally, and the fault occurs. The parameters are usually stored in the bubble memory or the CMOS RAM held by the battery. If the interference or the battery voltage is insufficient, the system parameters will be lost or changed, which will cause confusion. By checking and correcting the parameters, the fault can be eliminated.
Example 6: G1 8CP4 CNC grinding machine, CNC system is FANUC1 1M system, the fault phenomenon makes the machine work, CRT display does not have any alarm information.
Checking all parts of the machine and found that the CNC unit and the connection unit between the CNC and each interface are good. The final analysis is caused by the external data causing the data stored in the bubble memory to be confusing. Therefore, the contents of the bubble memory are all stored. After clearing and re-sending the various parameters of the CNC system according to the manual, the CNC machine tool will return to normal. In addition to the several inspection methods described above, there are measurement comparison method, tapping method, local temperature rising method, voltage drawing method and open loop detection method. These methods have their own characteristics. The maintenance should be based on the fault phenomenon, often at the same time. Using several methods, flexible use, comprehensive analysis of faults gradually reduce the scope of faults, in order to achieve the purpose of troubleshooting.
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