CNC machine tools are high-tech automated machine tools. It is a highly efficient and sophisticated advanced machining equipment that integrates electromechanical devices. CNC machine tools integrate servo drive, computer technology, confidential measurement, automation technology and sensor technology into one. The use of CNC machine tools has greatly increased the level of production in the machinery manufacturing industry, which has greatly increased production efficiency and reduced labor input. However, CNC machine tools also have their own shortcomings. The complexity of CNC machine tools determines that the people who use it must have a certain amount of corresponding knowledge. When using it, it must be careful and always pay attention to its meticulous maintenance. In the process of using CNC machine tools, hydraulic, mechanical, and electrical faults often occur, and the failure of the electrical system is the most frequent of these three faults. How to solve the failure of the electrical system has become a pressing problem for the mechanical industry.
Common faults in CNC machine tools Common faults in CNC machine tools can be divided into the following five types according to different classification methods. The first kind can be divided into hardware system faults and software system faults according to the locations where faults occur. What is a hardware system failure? Hardware system failure mainly refers to the failure of electronic components (electronics, printed circuit boards, electrical devices, etc.), limit mechanisms, etc. Software system failures are mainly due to errors in the programs controlled by the PLC logic, incorrect parameter settings, and errors in the machining programs of the parts. The second classification method can be divided into a non-diagnosis indication failure and a diagnosis indication failure according to whether there is an indication when the failure occurs. As the name implies, there is a diagnostic indication failure. When the machine tool is running, the diagnostic system can monitor the entire machining process. When a problem occurs in a certain step, it will immediately alarm or display the fault in text form. No diagnostics indicate a fault, ie there is no corresponding indication when a fault occurs. The occurrence of these failures was mainly caused by the use of machinery for many years, and mechanical parts were worn out, causing the matching of the procedures and machinery. The third kind is divided according to the probability of failure. If a certain fault occurs when the machine meets certain conditions, then the fault is a systematic one. A random failure is a failure that may occur when certain conditions are met. Random faults are more difficult to resolve because of their uncertainty. The fourth type is based on whether or not there is a destructive breakdown at the time of the failure. Destructive is called destructive failure, and non-destructive is called non-destructive failure. The last kind of fault is called the degradation of the machine tool. When this failure occurs, the machine tool can produce normal products but it can't produce qualified products.
Failure analysis of the electrical system of the numerical control machine tool Intuitive observation method Visual observation method is to use the senses to check the fault. The first step of the visual inspection method is to ask, that is, to ask the fault of the on-site personnel fault occurred process, the phenomenon of the occurrence and the consequences of the fault. The second step is to look at whether the various parts are in the normal state, and whether the corresponding electronic control device has an alarm signal. After these exclusions, check whether the resistance wire is burned out, whether the components are scorched or not, and the wire and cable. There is no phenomenon such as falling off. The third step is touch, that is, check whether the sockets are properly installed during power off, whether the circuit boards are installed and whether the signal wires are connected. The fourth step is to check if there is any fire, smoke or abnormal sound or abnormal smell after power on.
Instrument inspection method The instrument inspection method uses the corresponding electrical instrument to check the AC-DC voltage and the corresponding pulse signal in the circuit to find possible fault points.
The alarm indication and signal analysis method is to make full use of the alarm indicators and signals on a monitoring system to troubleshoot the fault. For the hardware system, the specific location of the fault is determined based on the alarm indicators on the electronic components and on the electrical device. The software system does not have specific alarm indications, but it can find out the possible fault points according to the alarm indications in the hardware system and the signal combination instructions.
Interface state inspection method The current CNC machine tool will cover the PLC. They are mainly connected by interface signals. Many of the symptoms of CNC machine tools are related to errors in the interface signals. To check if the interface signal is correct, just call it through the PLC program.
Parameter adjustment methods CNC machine tools, PLCs, and servo systems all contain many parameters to suit the machining needs of different machine tools. However, because they are used for too long, these parameters often cannot meet the requirements of the machine tools or their matching degree is reduced. Therefore, in order to continue to meet the production requirements of the machine tool, these parameters are sometimes changed accordingly.
Spare replacement method When a fault is determined on a circuit board but it is difficult to find the faulty component, spare parts can be replaced first in order not to delay production, and the location of the specific fault is checked afterwards, and then the repair is performed.
Maintenance and maintenance of CNC machine tools In view of the importance of CNC machine tools in the production of machinery, and the structure of CNC machine tools is so complicated, the machining manufacturers must ensure the maintenance and repair of CNC machine tools.
The basic conditions for electrical maintenance of CNC machine tools In order to maintain the electrical maintenance and repair of CNC machine tools, good maintenance conditions are very necessary. The first is personnel conditions. The quality and speed of maintenance of CNC machine tools mainly depend on the quality of the corresponding staff. The corresponding staff must first have a high degree of responsibility, understand the relevant knowledge and have a good professional qualities. Secondly, the staff must go through corresponding technical training before taking up the job, be able to be proficient in the corresponding operation steps, it is best to understand a foreign language, can read the relevant instructions. In addition to personnel conditions, good material conditions are also necessary.
The material conditions mainly include the first, the relevant manuals of the CNC machine tools, the maintenance record files, and the technical data related to the CNC machine tools. Second, it is necessary to make appropriate spare parts work for the components of CNC machine tools to prevent them from being confused if they need to replace components in the event of a failure. Third, we must prepare the necessary maintenance tools and install corresponding maintenance software on the computer.
For daily work, there are many that need attention. First of all, the operating room of CNC machine tools must be kept clean and clean to prevent metal powder, dust and other substances from damaging the machinery. Especially in summer, the weather is relatively hot and the machinery cannot dissipate heat by opening the CNC cabinet. The correct operation method is to use the corresponding heat dissipation tool or heat the program. Second, in the process of use, we must control the system overheating, regular inspection of the input and output devices. During work, check the cooling fan to make sure it works properly. Again, often check the DC motor brush, DC motor brush is an important part of the motor, its quality directly affects the operation of the entire CNC machine tool. The direct consequence of its damage is the flaw of the motor, so the worker should always check the status of the brush of the DC motor.
Eliminating measures for the failure of the electrical system of numerically-controlled machine tools The above describes the daily maintenance conditions of the electrical system of the numerical control machine tool. In general, if our staff strictly follows the above requirements, the probability of failure is relatively low. However, the possibility of a failure cannot be ruled out. Once the electrical system of the CNC machine tool fails, how can we solve it? Here we briefly introduce the different types of faults mentioned above.
The first type is hardware system and software system failure. In the event of a hardware system failure, the problem can be solved as long as the damaged parts are generally repaired or replaced. For software system failures, you need to change the corresponding data or program. If the situation is more complicated, you must modify the PLC program.
Second, there is a diagnostic indication failure and no diagnosis indication failure. If there is a diagnosis indication failure, it can be resolved as long as it is based on the corresponding diagnosis indication signal and the corresponding technical description. And for no indication of failure, it requires the corresponding staff to change according to the pre-failure, and then combine their own work experience to solve, so the comparison of these two kinds of failures, no diagnosis indicates that the failure is more difficult to solve.
The third kind, destructive failure and non-destructive failure. This kind of fault is mainly analyzed according to the phenomenon that appears when the fault occurs, find out the corresponding fault source, and then eliminate it. This method has certain risks and may damage the machinery.
Fourth, system failures and random failures. Elimination of such failures is difficult and requires repeated experiments to determine the exact location of the failure.
The fifth kind is the failure of machine tool movement characteristics. This failure can be eliminated by changing the corresponding data and program.
Summary With the continuous development of computer technology, automation technology, and sensor technology, CNC machine tools that use them as technical support will become more and more advanced. The position of CNC machine tools in the machining industry will also become more and more important. Such an important position of CNC machine tools and the complexity of its programs determine the daily maintenance and repair of CNC machine tools is particularly important. First of all, the corresponding staff must ensure that the CNC machine tool has good warranty conditions. The specific requirement is that the staff must have good professional ethics and professional knowledge reserves. Second, the working environment should be kept clean. Again, it is during the operation of the machinery to be careful. In the end, it is to make every preparation for maintenance. If these are done, failure cannot be avoided, then specific issues must be specifically addressed, and different maintenance strategies should be adopted for different failures. Although the maintenance technology of the electrical system of CNC machine tools is still not advanced enough, but the era is developing and the technology is improving. It is believed that in the near future, the maintenance technology of the electrical systems of CNC machine tools will be greatly improved.
