First, do not blindly believe in the quality of imported CNC equipment
Imported CNC equipment is mostly the product of today's most cutting-edge technology applications. However, due to the rush of manufacturers, there is not enough time-testing, and there are inevitably some imperfections in design and manufacturing. The cylinder bore honing machine purchased from GEHRING Company of Germany adopts advanced numerical control hydraulic servo technology to better solve the closed-loop control of the mesh angle, depth, cylinder bore diameter and cylindricity. The company is a world-renowned company, and its newly developed laser honing technology is being tested at the Mercedes-Benz factory. It is reported to be very successful. However, it is the equipment produced by such a well-known company. After more than one year of use, there are often some unexplained failures such as sudden interruption of operation and equipment parking. Sometimes it will return to normal after restarting, sometimes it will be normal after repeated times, sometimes there is no problem for a period of time, sometimes it is continuous. The alarm message indicates a "SYSTEMCOMMUNICATION" system communication failure.
The characteristics and maintenance ideas of imported CNC machine tools
This phenomenon is generally referred to as a "soft fault." At first, it was suspected that it was caused by grid noise and harmonic interference, and the quality of the grid was tested. The test report shows that the grid harmonics are exceeded and filtering is recommended. Under normal circumstances, the harmonic quality of the power grid is mostly exceeded. Grid interference is only an external cause, and the overall anti-interference performance of the system is the internal cause. Most imported CNC equipment has simple grid noise filtering technology. After more than one year, the problem is solved, indicating that the system can resist external interference. Nowadays, either the external interference becomes stronger or the system's anti-jamming performance is worse. From the normal operation of other imported CNC equipment in the factory, it is likely to be a system problem. When testing the GEHA25 module, it was found that the module had obstacles during power-on communication, the connection speed was slow, and the anti-interference performance was poor, but it was ignored by the host. After replacing a new module, the device runs stably and the fault disappears.
Originally, this CNC-GOP system is a patented product jointly developed by GEHRING and SIEMENS. It has strong special functions, convenient control and stable performance. Because it is a newly developed system, it has not passed sufficient time test, and it has anti-interference and poor stability. In fact, there are many similar problems in the manufacturers of equipment manufacturing technology. Therefore, we cannot blindly worship Western high technology. We must see that even advanced technologies are still developing, and there may still be defects. The more advanced the technology, the more likely it is to be defective. When repairing imported CNC equipment, it is necessary to recognize its technological advancement and to see its deficiencies in a realistic manner.
Second, you must read the alarm information analytically.
The control part of the numerical control system of the imported equipment is designed rigorously. A seemingly small anomaly will also receive the alarm entry and may cause the machine to stop. In the process of actually repairing imported CNC equipment, reading the alarm information is the most basic and convenient method for seeking quick repair. But not every piece of information is credible, and every piece of information can be used. In the numerous alarm messages, there are many that may be useless or even misleading for maintenance. It is necessary to be good at extracting fine information from these messages.
For example, the CNC cam grinder produced by SCHAUDT in Germany is a CBN grinding machine with a grinding cam type. Every time you turn it on, there will be a lot of alarms. In fact, they are all just starting up. There are a lot of preparation conditions that are not satisfied yet. It has no practical significance.
Once, the machine alarm shows that the "Filterofoildirty" static pressure system filter is dirty. The equipment spindle slide uses static pressure floating guides. The filter was removed and cleaned, but it was still alarmed after installation; a new filter was installed and the alarm could not be eliminated. Carefully check the PLC alarm code, and find out that the fault alarm condition is that the pressure sensor of the static pressure floating rail does not work. The fault design explanation is that when the pressure sensor does not sense the pressure, it is understood that the filter is blocked. But by careful inspection, the filter is good, just because there is a problem with the pressure sensor, the signal is sent without signal.
The given information of an alarm is obtained by the designer based on the PC simulation. It is not his experience of on-site maintenance for many years. It is often designed according to the conventional logic, with the designer's personal understanding of the simulation results. However, the occurrence of faults is often unexpected, or it is necessary to reason and judge based on fault phenomena and random data. The correct attitude to the alarm information provided by the machine is: Do not believe it, but not believe it. Do not trust the alarm information, do not fall into the trap of false alarm information.
Third, a full backup must be made when the machine is first used.
Imported CNC equipment mostly uses modern microelectronics numerical control technology and is managed by PC. It should be said that the CNC machine manages CNC-PLC and OP system, which greatly improves the operation performance and maintainability of the machine tool. However, if you forget to back up in time, once the machine program or parameters are lost, it will cause trouble. Especially in the case of various computer viruses, it is more necessary to back up the PC system.
After a holiday, an imported CNC device is turned on and the OP panel signal light flashes. After inspection, it was confirmed that all the CNC and PLC parameters in the SIEMENS system were lost. Immediately after the program recovery work, the CD, floppy disk and other data brought in the data at the time of import are input into the system, and the machine still cannot operate. Originally, most of these materials were backed up by the factory at the factory. After trial operation and on-site operation, some programs, especially the vast majority of parameters, were greatly modified. In particular, the SIEMENS system is required by the European safety standards to be signed after the program is written. If you don't have the latest backup at hand, you will be very passive when you are unfamiliar with the recovery system.
How can we avoid the passive occurrence after losing the program? It is to be the worst case - the preparation of the hard disk damage. After the hard disk is damaged, all efforts cannot be made. Of course, it is also possible to re-create a new system hard drive, but most of the hard drives in imported CNC equipment are non-standard. Some can be replaced with a notebook hard drive, but the success of this attempt is not very big. Especially for automobile manufacturers, it is required to repair the equipment in the shortest possible time, and it is impossible to give too much time for hard disk recovery work.
In order to cope with the sudden loss of possible system programs, there are several effective methods:
(1) For a complete backup of the D disk of the PC hard disk, it is necessary to clearly mark the important identifiers such as file name, product name, parameter type, date, and so on. This is the most basic and convenient backup method, and can be resumed as soon as the machine program or parameters are lost. The disadvantage is that once the PC itself fails, the program recovery cannot be performed.
(2) Make a GHOST backup of the system disk C disk on the D disk of the PC. This is a simple and efficient way to deal with PC system failures (including virus damage), and sometimes all anti-virus methods have not been restored to the system disk C drive GHOST once effective. GHOST uses V7.50 version to run better under DOS.
(3) Burn the GHOST backup of the PC hard disk content into the CD. This method is safe and reliable, and is a good way to back up files outside the machine.
(4) Copy the hard disk. This is the safest and most reliable method. Purchase a new hard disk that is exactly the same as the PC. After copying it, save it properly. Once the PC hard disk fails, replace the backup hard disk. The advantage is fast and reliable, and the disadvantage is high cost.
Fourth, comprehensive system considerations, scientific reserve spare parts
In order to ensure the normal operation of imported CNC equipment in production, it is recommended to repair the damaged device by yourself. However, CNC devices generally have high technical content, and most of them have intellectual property protection, which cannot be easily repaired. The necessary spare parts must be reserved. The size and variety selection of spare parts reserves has always been a controversial topic. Too much reserves and too much capital is used to form waste; too little reserves can not meet production needs. The spare parts reserve for imported CNC equipment can be determined according to the following factors:
(1) The reserve quantity generally does not exceed 5% of the equipment price at the time of purchase. Of course, this is a reference quantity, and the other factors of the equipment should also be considered.
(2) Refer to the machine and power complexity coefficients of imported CNC equipment. The complexity factor is large, and the corresponding reserve amount can be slightly larger, and conversely, it can be slightly smaller.
(3) Try to select the CNC system of the same manufacturer at the time of purchase, which can greatly save the cost of spare parts.
(4) The software and hardware components of imported CNC equipment are different. For products that are developed by some manufacturers, they should be stored as much as possible according to the supply situation. Because these spare parts usually have narrow supply channels and long procurement cycles, they are “monopoly products” and it is necessary to “prepare them”.
(5) Reserve according to market supply. Like the road products SIEMENS, FANUC and other products, the market supply is sufficient, and can be stocked according to the purchase delivery period. If it can be purchased in the short term, it can suspend the procurement. If the delivery time is long, it can be purchased properly.
(6) Determine the spare parts reserve based on production output. The spare parts reserve is, in the final analysis, an “insurance investment” to ensure normal production without interruption. The greater the output, the greater the “insured amount”, which is in line with economic laws. Two shifts of production should be larger than the single shift production, and vice versa.
Article link: China Machine Tool Business Network http://www.jc35.com/news/detail/56795.html
