Talking about the Maintenance and Maintenance of CNC Machine Tools

The maintenance of machine tools is not difficult for a student majoring in numerical control. Here I recommend the maintenance and maintenance of CNC machine tools. Welcome to read!

As a kind of high-precision automation equipment, the safe and reliable operation of CNC machine tools depends on the correct use and daily maintenance of the machine tools to a great extent. In order to ensure the long-term safe and stable operation of machine tools, reduce maintenance costs, discover and eliminate hidden dangers in time, and thus improve the economic benefits of enterprises. The author puts forward the following practical diagnosis, repair and maintenance methods for your reference through the typical faults of maintenance and maintenance of CNC machine tools in daily work.

Keywords: benefits of automatic diagnosis and maintenance of CNC machine tools

1 CNC machine tool fault classification

Common faults are divided into mechanical faults and electrical faults according to their causes. Therefore, it is necessary to judge whether it is a mechanical fault or an electrical fault during maintenance. Check the electrical system first to see whether the program can run normally, whether the function keys are normal and whether there is any alarm phenomenon, and then check whether there is no phase defect, overcurrent, undervoltage or abnormal action. According to the above situation, it can be preliminarily judged whether the fault is mechanical or electrical.

2 Typical fault diagnosis and troubleshooting methods

2. 1 routine inspection method ① alarm handling: when the CNC system fails, the fault signal and corresponding information are generally given on the operation panel. Usually there are detailed alarm contents and handling methods in the operation manual or adjustment manual of the system. At the same time, you can use the operation panel or programmer to find out the corresponding signal state according to the circuit diagram and PLC program, and find out the fault point according to the logical relationship for processing. ② Troubleshooting without alarm or alarm: When the system can't run or stop, or the system can't work normally without alarm, it is necessary to analyze and make a correct judgment according to the system state information before and after the fault and the mastered theoretical basis. This PLC interrupt state analysis adopts programmable controller, and the interrupt reason is stored in interrupt stack.

For example, a SCHIESS VMG6 seven-axis five-linkage CNC machine tool adopts Siemens 840D system, and its programmable controller S7300 is interrupted during operation. The fault cause can be found quickly by using the method of system diagnosis interrupt stack. Access this function through SIMATIC manager and select menu function PLC->; Diagnosis/Settings-> Module information->; Diagnostic buffer, which can be opened. All events that can be used for system diagnosis are stored in the diagnostic buffer in sequence. After selecting an event, in? Detailed information about events can be seen in the information box "Details of Events": event (ID) code and event number, block type and number, and the relative STL line address of the instruction that caused the event according to the event. Click [Event Help] to open the event help information window. Click the [Open Block] button to open the interrupt block in the CPU online, which is very fast and effective in actual maintenance. Maintenance personnel should be fully familiar with some special treatment methods of system self-diagnosis function. In this way, you will take fewer detours and quickly troubleshoot.

2.2 Initialization method In general, the system alarm caused by instantaneous fault can be cleared by hardware reset or switching the system power supply in turn; If the working storage area of the system is chaotic due to power failure, unplugging the circuit board or battery undervoltage, the system must be initialized and cleared.

For example, a German PFH 100KW-6-6m CNC gantry milling and boring machine adopts Siemens 840C CNC system. Because the working storage area of the system is chaotic, it is only set in an initialization interface after switching, so the system cannot enter at all, and the general reset is invalid. Therefore, the system must be initialized and cleared, so the method of initialization and reset is adopted to enter the [[Start] menu-> Use [general reset mode information at startup]-> select [[End gen reset mode] to execute this special reset method, and then the system can be restarted to run normally and the fault can be solved.

2.3 parameter correction method in the maintenance of CNC machine tools, it is sometimes necessary to use certain parameters to adjust the machine tool, and some parameters should be corrected according to the running state of the machine tool. This method is very effective in cooperation with mechanical maintenance. For example: a French forest? NUM 1060 system is used for 250 CNC floor boring machine. Although the X-axis guide rail has been overhauled, the column operation in this direction still can't meet the machining requirements. Because the front guide rail has been seriously damaged, we try to change the parameters on the basis of limited mechanical adjustment ability. Step by step adjust the position of the loop gain coefficient of the p 2 1 servo system. The setting steps and operation methods of the NUM machine parameters are as follows: ① Press the soft key FLL-Select Utility ② after power-on; ② Select item 0 to access utility ③; ③ Select item 5 to set data ④; ④ When "parameter change is normal" appears, the screen warns that the machine control will stop. (Y/N), press the Y letter ⑤ key, and the machine setting data 0 display 1 change screen will appear. If it is changed, please enter 1⑥, and the parameter will appear? If the parameter P2 1 is changed, please type P2 1⑦ After the parameter appears, move the cursor to the word # and press Enter to enter the parameter value, then press CTRL+X Off to reset and exit the parameter setting.

After several debugging, the value of P2 1 was finally reduced from 950 to 700, which improved the crawling failure of machine tools and ensured the production. Therefore, maintenance personnel should check more information and know more about the significance of various parameters of machine tools and the methods of parameter change. In this way, on the basis of having certain mechanical adjustment ability, by modifying the numerical control data, the performance of the machine tool can be better played and its machining accuracy can be improved.

3 Maintenance of electrical, hydraulic and cooling lubrication systems of CNC machine tools

3. 1 Electrical system maintenance

3. 1. 1 Remove the dust in the electrical cabinet and keep the surfaces of circuit boards and electrical components clean. Due to the high ambient temperature, air conditioning devices are usually installed in numerical control cabinets. After installing the air conditioner, the reliability of the numerical control system is obviously improved.

3. 1.2 electrical appliances around the machine tool should check that the connecting wires and cables between various parts of the machine tool can not be corroded and damaged, and handle them in time after finding hidden dangers to prevent short circuit and open circuit. Tighten the wire pressing screws on the terminals and electrical components to make the terminals firm and reliable.

3. 1.3 machine tool power check whether the power supply of the CNC system is normal, whether the voltage fluctuation is within the allowable range, and whether the grounding of the whole CNC electrical system is good and reliable. Reliable grounding is the guarantee of anti-interference and reliable operation of the system.

For example: an American AB 10? During the debugging of 40-meter CNC lathe and milling machine, it is found that the communication of machine tools is often suddenly interrupted. It is found that the shielding layer of the electric cabinet is poorly grounded, which causes the distortion of the program signal. This is the reason for the above problems. After grounding the cable shielding layer and all parts of the machine tool power distribution cabinet well, troubleshoot.

3.2 The maintenance of hydraulic system should change the oil in the oil tank regularly, and sometimes the choice of machine tool oil number depends on the environmental temperature and oil system at the work site. Check and replace the seals regularly, and clean the oil tank and pipeline to prevent the hydraulic system from leaking. Check whether the noise, vibration, pressure and temperature of the system are normal, and eliminate the fault in the bud.

3.3 Maintenance of cooling and lubrication system Check the amount of oil in the lubricating oil tank of the guide rail and whether the lubricating oil pump can be started and stopped regularly. Check the oil pump regularly, clean the filter and oil tank and change the lubricating oil. If the cutting fluid is too dirty, clean the cutting fluid tank and replace the cutting fluid. Therefore, in the process of use, in addition to mastering the performance and careful operation of CNC machine tools, we should also pay attention to eliminating various unfavorable factors.

It should be emphasized that although there are many kinds of CNC machine tools, the maintenance methods of all kinds of CNC machine tools are basically the same. As long as the operators and maintenance personnel do careful operation and maintenance, they can find and eliminate hidden dangers in time, reduce maintenance costs, thus ensuring the safe and reliable operation of CNC machine tools for a longer period of time, effectively implementing the leading idea of equipment management, and effectively ensuring and improving the economic benefits of enterprises.

References:

[1] Liu Yongjiu. Fault diagnosis and maintenance technology of CNC machine tools. Beijing: Machinery Industry Press. 2006。

[2] Guan Shichang. Several problems in the maintenance of nc machine tools. Equipment management and maintenance 1990 (2).

[3] Cui Hongcai. Talking about the maintenance of numerical control machine tools. Equipment management and maintenance 200 1. Ninth place