Model essay on maintenance of CNC machine tools Keywords: CNC system battery is needed for processing and maintenance of general machine tools. This material engineering paper comes from the network and the copyright belongs to the author. The application and maintenance of CNC machine tools The development of science and technology requires high accuracy and complexity of mechanical products, and the upgrading of products is also accelerating, which requires not only accuracy and efficiency, but also versatility and flexibility of machine tools and equipment. Numerical control machine tool is a new type of automatic machine tool to meet this requirement. CNC machine tool integrates microelectronics, computer technology, automatic control technology, servo drive technology and precision machinery technology, and is a typical product with high electromechanical integration. It is an important part of mechatronics and an important symbol of the technical level of modern machine tools. Numerical control machine tool embodies the mainstream of machine tool technology progress in the world, is an important index to measure the technical level of mechanical manufacturing, and plays an important basic core role in advanced manufacturing technologies such as flexible production and computer integrated manufacturing. Therefore, how to use CNC machine tools better is a very important issue. Because CNC machine tool is an expensive precision equipment, its maintenance can not be ignored. 1. CNC machine tools 1. The concept of NC machining. The working principle of CNC machine tools is to express all kinds of operations (such as spindle speed change, workpiece loosening and clamping, feed and retract, start and stop, and automatically turn off coolant) and steps required in the machining process with digital codes. Digital information is sent to the NC device through the control medium (such as punched paper tape or disk), and the NC device processes and calculates the input information and sends it out. Therefore, the key of NC machining is the acquisition of machining data and process parameters, that is, NC programming. NC machining generally includes the following contents: (1) Analyze the drawings to determine the parts that need NC machining; (2) Using graphic software (such as CAXA manufacturing engineer) to model the parts that need NC machining; (3) According to the machining conditions, select appropriate machining parameters and generate machining trajectories (including rough machining, semi-finish machining and finish machining trajectories); (4) Ballistic simulation test; (5) generating a G code; (6) Able to machine. 2. CNC machine tools (1) are characterized by high flexibility. Machining parts on CNC machine tools mainly depends on the machining program. Unlike ordinary machine tools, there is no need to manufacture and replace many tools and fixtures, and there is no need to adjust the machine tools frequently. Therefore, CNC machine tools are suitable for changing parts frequently. That is, it is suitable for small batch production and new product development, which shortens the production preparation cycle and saves a lot of process equipment costs. (2) The machining accuracy of CNC machine tools with high machining accuracy can generally reach 0.005 ~ 0. 1 mm, and the CNC machine tools are controlled in the form of digital signals. Every time the numerical control device outputs a pulse signal, the moving parts of the machine tool move by a pulse equivalent (generally 0.00 1mm), and the average error of the reverse clearance and pitch of the machine tool feed transmission chain can be compensated by the numerical control device. (3) The processing quality is stable, and the same batch of parts can be processed reliably. On the same machine tool, under the same processing conditions, using the same tools and processing procedures, the tool paths are exactly the same, the parts are consistent and the quality is stable. (4) CNC machine tools with high productivity can effectively reduce the processing time and auxiliary time of parts. The spindle speed and feed range of CNC machine tools are large, which allows the machine tools to carry out powerful cutting with large cutting volume. At present, CNC machine tools are entering the era of high-speed machining. The rapid moving and positioning of moving parts of CNC machine tools and high-speed cutting reduce the turnaround time between semi-finished products and improve production efficiency. (5) Improve working conditions. After the NC machine tool is adjusted before processing, the program is input and started, and the machine tool can automatically process continuously until the processing is finished. Operators are mainly engaged in inputting programs, editing, loading and unloading parts, preparing tools, observing machining status and checking parts. The labor intensity is greatly reduced, and the labor of machine tool operators tends to be intelligent. In addition, machine tools are generally closed processing, clean and safe. (6) It is beneficial to the processing and production management of modern CNC machine tools. The processing time can be accurately estimated in advance, and the tools and fixtures used can be standardized and modernized. Numerical control machine tools use digital signals and standard codes as control information, which is easy to realize the standardization of processing information. At present, it has been organically combined with computer-aided design and manufacturing (CAD/CAM), which is the basis of modern integrated manufacturing technology. 3. Precautions for using CNC machine tools Before using CNC machine tools, you should carefully read the operating instructions of the machine tools and other relevant materials, so as to operate and use the machine tools correctly, and pay attention to the following points: (1) Machine tool operators and maintenance personnel must be professionals who have mastered the corresponding machine tools' professional knowledge or have received technical training, and must operate the machine tools according to the safety operation rules and regulations; (2) Non-professionals are not allowed to open the cupboard door. Before opening the cupboard door, they must confirm that the main power switch of the machine tool has been turned off. Only professional maintenance personnel are allowed to open the electric cabinet door for power-on maintenance; (3) Except for some parameters that can be changed by users, other system parameters, spindle parameters, servo parameters, etc. It can't be modified by the user privately, otherwise it will bring harm to the operator, such as equipment, workpieces and personnel. (4) After modifying the parameters, when the machine tool is processed for the first time, the machine tool is put into trial operation by locking the machine tool and single program section without installing tools and workpieces, and the machine tool is used after it is confirmed to be normal; (5) The PLC program of the machine tool is designed by the machine tool manufacturer according to the needs of the machine tool and does not need to be modified. Incorrect modification and operation of the machine tool may damage the machine tool and even hurt the operator; (6) It is recommended that the machine tool run continuously for 24 hours at most. If the continuous operation time is too long, it will affect the life of electrical system and some mechanical devices, thus affecting the accuracy of machine tools; (7) All connectors and joints of the machine tool are not allowed to be plugged and unplugged with electricity, otherwise it will cause serious consequences. Second, the maintenance of CNC machine tools CNC system is the core component of CNC machine tools. Therefore, the maintenance of CNC machine tools is mainly the maintenance of CNC system. After a long period of use, the performance of electronic components will age or even be damaged, especially some mechanical parts. In order to prolong the life and wear cycle of parts as much as possible, and prevent all kinds of faults, especially vicious accidents, it is necessary to carry out daily maintenance of CNC system. To sum up, we should pay attention to the following aspects. 1. Formulate the rules and regulations for daily maintenance of CNC system, and determine their own maintenance procedures according to the characteristics of each component. For example, clearly specify which parts need to be cleaned every day (for example, the input/output unit photoelectric reader of the numerical control system needs to be cleaned, whether the mechanical structure is well lubricated, and so on). ), and which parts should be checked or replaced regularly (for example, the brush and commutator of DC servo motor should be checked once a month). 2. The doors of CNC cabinets and high-voltage cabinets should be opened as little as possible, because the air in machining workshops generally contains oil mist, dust and even metal powder. Once it falls on the printed circuit or electrical components in the numerical control system, it is easy to cause the insulation resistance between components to drop, and even lead to the damage of components and printed circuits. In summer, some users open the door of the numerical control cabinet to dissipate heat in order to overload the numerical control system for a long time, which is an unacceptable method and will eventually lead to accelerated damage of the numerical control system. The correct way is to reduce the external environment temperature of CNC system. Therefore, there should be a strict rule that unless necessary adjustments and maintenance are made, it is not allowed to open the cupboard door casually, let alone open the cupboard door when using it. 3. Regularly clean the cooling and ventilation system of the numerical control cabinet. Check whether the cooling fan on the numerical control cabinet works normally every day, and check whether the air duct filter is blocked every six months or every quarter according to the working environment. If the dust on the filter screen accumulates too much, it needs to be cleaned in time, otherwise the temperature in the cabinet of the numerical control system will be very high (generally not allowed to exceed 55℃), which will lead to overheating alarm or unreliable work of the numerical control system. 4. Frequently monitor the grid voltage used in the numerical control system. The numerical control system produced by FANUC allows the grid voltage to fluctuate within the range of 85% ~ 1 10% of the rated value. If it exceeds this range, the system will not work normally and even damage the electronic components inside the CNC system. 5. Replace the memory battery regularly. There are two kinds of memories in the numerical control system produced by FANUC: (1) bubble memory without battery maintenance. (2) CMOS RAM devices that need to be saved by batteries have a rechargeable battery maintenance circuit in order to save the stored contents when the numerical control system is not powered on. When the numerical control system is powered on, CMOS RAM is powered by a +5V power supply through a diode, and the rechargeable battery is charged. When the CNC system cuts off the power supply, it will be powered by the battery to maintain the information in CMOS RAM. Under normal circumstances, even if the battery is not out of order, it should be replaced once a year to ensure the normal operation of the system. In addition, it must be noted that battery replacement must be carried out under the power supply state of the numerical control system. 6. Maintenance of CNC system when it is not used for a long time In order to improve the utilization rate of CNC system and reduce the faults of CNC system, CNC machine tools should be used at full load instead of being idle for a long time. For some reason, when the CNC system is idle for a long time, in order to avoid damaging the CNC system, we need to pay attention to the following two points: (1) Power on the CNC system frequently, especially in the rainy season when the environmental humidity is high, when the machine tool is locked (. The heat of electrical components is used to dispel the moisture in the numerical control system to ensure the stability and reliability of electronic components. Practice has proved that frequent energization is an effective measure to reduce the failure rate in areas with high air humidity. (2) If the CNC machine tool adopts DC feed servo drive and DC spindle servo drive, the brush should be taken out of the DC motor, so as to avoid the corrosion of the commutator surface due to chemical corrosion, worsen the commutation performance and even damage the whole motor.