CNC machine tool is a kind of high-efficiency automatic machine tool. He integrated the new technical achievements in various fields such as computer technology, automation technology, servo drive, precision measurement and precision machinery, and is a new industrial control technology. Due to its good economic performance and high production efficiency, it is playing an increasingly important role in production. In order to improve the utilization rate of the machine tool and improve the system's effectiveness, the general method of troubleshooting and maintenance of the CNC system is discussed in light of the actual work. To improve the maintenance of CNC machine tools.
First, the intuitive method
The maintenance personnel observed the various parts of the system through the observation of abnormal phenomena such as light, sound, and taste at the time of failure, and narrowed down the fault to one module or one printed circuit board.
Example 1: Sudden shutdown occurs during the machining of CNC machine tools. Open the CNC cabinet and found that Y-axis motor main circuit fuse burned out. After careful observation, check the parts related to the Y-axis, and finally found that the Y-axis motor power line sheath was scratched by a hard object, and the damage occurred at the machine tool casing. Short-circuit burn-out insurance, after replacing the Y-axis motor power line, the fault is eliminated and the machine tool returns to normal.
Second, self-diagnosis function method
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 status of the numerical control system at any time. In the event of an abnormal situation, the immediate display of alarm information on the CRT or the use of light-emitting diodes to indicate the general cause of the fault is the most effective method of maintenance.
Example 2: AX15Z CNC lathe equipped with FANUC1 0TE-F system, fault display:
FS10TE 1399B
ROM TEST:END
RAM TEST:
The CRT display shows that the ROM test passed and the RAM test failed. The RAM test fails to pass, it is not necessarily a RAM failure. It may be that the parameters in the RAM are lost or the battery is not in contact with the parameters. The cause of the failure is due to poor battery contact after the battery is replaced. Therefore, the above fault phenomenon occurs when the RAM is turned on.
Third, the functional program test method
The function program test method is to use the manual programming or automatic programming method of the common functions and special functions of the numerical control system to compile a functional test program into 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 causes of failure.
Example 3: A CNC milling machine using the FANUC 6M system has a crawling phenomenon during the curve processing of the workpiece. With the self-programmed function test program, the machine tool can run smoothly to complete various predetermined actions, indicating that the machine tool numerical control system is working properly. The inspection of the used curve machining program found that the G61 command was used during programming, that is, each processing section had to be checked once without stopping, so that the machine tool appeared a crawl phenomenon. The G61 command was changed to the G64 (continuous cutting method) command. After the replacement, the crawling phenomenon is eliminated.
Fourth, the exchange method
The so-called exchange method is to analyze the cause of the failure of the general circumstances, the use of spare printed circuit boards, templates, integrated circuit chips or components to replace doubtful parts, thus reducing the scope of the fault to the printed circuit board or chip level.
Example 4: The rotation table of TH63 50 machining center rotates more than once after being lifted, and there is no deceleration, no alarm signal appears. This kind of failure may be caused by a malfunction of the simple position controller of the rotating workpiece stage. In order 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 that of the turntable. Then using the exchange method to check, exchange the positioner of the tool magazine and the turntable, and set the position controller of the tool changer according to the setting of the turntable position controller. After the exchange, the tool magazine will rotate more than once. The turret was operating normally, confirming that the fault was actually on the turret's positioner.
V. Principle analysis
According to the principle of CNC composition, the logic level and characteristic parameters of each point are analyzed logically, and the analysis and judgment are started from the working principle of each component of the system to determine the maintenance method of the fault location. 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, and it is possible to locate the fault site.
Example 5: The Y axis feed is out of control on the PNE71 0 CNC lathe. No matter if it is jog or program feed, the guide rail cannot stop once it is moved until the emergency stop is pressed.
According to the basic principle of numerical control system position control, it can be determined that the fault is on the X-axis position loop, and the position feedback signal may be lost. In this way, once the numerical control device gives the command position of the feed, the actual position of the feedback is always Zero, the position error can not be eliminated, resulting in machine tool feed out of control, remove the position measuring device pulse encoder for inspection, found that the encoder filament has been broken, resulting in no feedback input signal, replace the Y axis encoder, troubleshooting.
Sixth, parameter inspection method
When the numerical control system finds a fault, it should check the system parameters in time. The change of system parameters will directly affect the performance of the machine tool, or even make the machine tool unable to work normally. If the fault occurs, the parameters are usually stored in the bubble memory or the CMOS RAM held by the battery. Once the outside Interference or insufficient battery voltage can cause system parameters to be lost or change to cause chaos. By checking and correcting parameters, faults can be eliminated.
Example 6: G1 8CP4 CNC grinding machine, CNC system is FANUC1 1M system, failure phenomenon makes the machine tool can not work, CRT monitor without any alarm information.
Examining all parts of the machine tool, it was found that the CNC unit and the connection unit between the CNC and each interface were all good. The final analysis was caused by the disturbance caused by external disturbances in the data stored in the bubble memory. Therefore, all the contents of the magnetic bubble memory were stored. After clearing and re-entering the CNC system parameters according to the manual, the CNC machine tool will return to normal. In addition to the several inspection methods described above, there are measurement and comparison methods, tapping methods, local heating methods, voltage pulling methods, and open-loop testing methods. These methods have their own characteristics, and maintenance should be based on the phenomenon of failure, often at the same time. Several methods are used flexibly to comprehensively analyze the fault and gradually narrow the fault to achieve the purpose of troubleshooting.
