trait
The operation and monitoring of CNC machine tools are completed in this CNC unit, which is the brain of CNC machine tools. Compared with ordinary machine tools, CNC machine tools have the following characteristics: ● High machining accuracy and stable machining quality; ● Multi-coordinate linkage can be carried out to process parts with complex shapes; ● When the machined parts change, it is generally only necessary to change the numerical control program, which can save the production preparation time; cnc bending machine
● The machine tool itself has high precision and rigidity, and can choose favorable processing dosage and high productivity (generally 3~5 times that of ordinary machine tools); The machine tool has a high degree of automation, which can reduce labor intensity; ● Require higher quality of operators and higher technical requirements of maintenance personnel. CNC machine tools are generally composed of the following parts: ● Main machine, which is the theme of CNC machine tools, including machine bed, column, spindle, feed mechanism and other mechanical parts. It is a mechanical component used to complete various cutting processes. numerical control machine
● CNC device is the core of CNC machine tools, including hardware (printed circuit board, CRT display, key box, paper tape reader, etc.). ) and corresponding software are used to input digital parts programs, and complete the storage, data conversion, interpolation operation and various control functions of input information. ● Driving device is the driving part of the executive mechanism of CNC machine tools, including spindle driving unit, feed unit, spindle motor and feed motor, etc. Under the control of numerical control device, he realizes the spindle and feed drive through electric or electro-hydraulic servo system. When multiple feeds are linked, positioning, straight line, plane curve and space curve can be processed. ● Auxiliary equipment refers to some supporting components necessary for the operation of CNC machine tools, such as cooling, chip removal, lubrication, lighting and monitoring. It includes hydraulic and pneumatic devices, a chip removal device, an exchange workbench, a numerical control turntable and a numerical control indexing head, as well as a cutter and a monitoring detection device. ● Programming and other auxiliary equipment can be used to program and store parts outside the machine. Since MIT developed the first CNC machine tool in the world in 1952, CNC machine tools have been widely used in manufacturing industry, especially in automobile, aerospace and military industry, and CNC technology has developed rapidly in both hardware and software.
Edit the content of this paragraph
In NC machining, NC milling is the most complicated and needs to solve the most problems. Besides CNC milling, CNC programming such as CNC wire cutting, CNC EDM, CNC turning and CNC grinding all have their own characteristics. The function of the servo system is to send the pulse from the numerical control device to the structure of the numerical control machine tool.
Motion number of moving parts of machine tool. Specifically, it consists of the following parts: the structure of CNC machine tools
host machine
He is the main body of CNC machine tools, including machine bed, column, spindle, feed mechanism and other mechanical parts. It is a mechanical component used to complete various cutting processes.
Digital control equipment
It is the core of CNC machine tools, including hardware (printed circuit board, CRT display, key box, paper tape reader, etc. ) and corresponding software are used to input digital parts programs, complete the storage of input information, data conversion, interpolation operation and realize various control functions.
driving gear
It is the driving part of the executive mechanism of CNC machine tools, including spindle drive unit, feed unit, spindle motor and feed motor. Under the control of numerical control device, he realizes the spindle and feed drive through electric or electro-hydraulic servo system. When multiple feeds are linked, positioning, straight line, plane curve and space curve can be processed.
ancillary equipment
Refers to some parts of CNC machine tools that are necessary to ensure the operation of CNC machine tools, such as cooling, chip removal, lubrication, lighting, monitoring, etc. It includes hydraulic and pneumatic devices, a chip removal device, an exchange workbench, a numerical control turntable and a numerical control indexing head, as well as a cutter and a monitoring detection device. Programming and other auxiliary equipment: it can be used to program and store parts outside the machine.
Edit this paragraph classification and application
Classification by process use
Metal cutting CNC machine tools, including CNC lathes, CNC drilling machines, CNC milling machines, CNC grinding machines, CNC boring machines and machining centers, all have structures suitable for CNC machine tools.
Used for single piece, small batch, multi-variety and parts processing, with good dimensional consistency, high productivity and automation, and high equipment flexibility. Metal forming CNC machine tool; This kind of machine tools include CNC bending machine, CNC combined punching machine, CNC pipe bender, CNC rotary indenter, etc. CNC special machining machine tools; This kind of machine tools include CNC wire cutting machine tools, CNC EDM machine tools, CNC flame cutting machine tools, CNC laser cutting machine tools, special combination machine tools and so on. Other types of numerical control equipment; Non-processing equipment adopts numerical control technology, such as automatic assembly machine, multi-coordinate measuring machine, automatic plotter, industrial robot and so on.
Classification by exercise mode
Point control; The characteristic of point-controlled CNC machine tool is that the moving parts of the machine tool can only move from one position to another accurately, and no machining process is carried out during the movement and positioning. Such as CNC drilling machine, CNC coordinate boring machine, CNC welding machine, CNC pipe bender, etc. Linear control; The characteristic of point-to-point linear control is that the moving parts of the machine tool not only need to be accurately moved and positioned from one coordinate position to another coordinate position, but also can realize linear feed movement parallel to the coordinate axis or control two coordinate axes to realize diagonal feed movement. Contour control; The characteristic of contour control CNC machine tool is that the moving parts of the machine tool can realize simultaneous linkage control of two coordinate axes. It requires not only to control the coordinate position of the starting point and the ending point of the moving parts of the machine tool, but also to control the speed and displacement of each point in the whole machining process, that is, to control the motion trajectory and machine the parts into straight lines, curves on the plane or curved surfaces in space.
Classification by control mode
Open loop control; That is, the control mode without position feedback device. Semi-closed loop control; It refers to installing an angular displacement detection device on the shaft of the open-loop control servo motor, and indirectly controlling the workshop by detecting the rotation angle of the servo motor.
The detect displacement of that moving part is fed back to the comparator of the numerical control device, which compare with the input command, and the moving part is controlled by the difference. Closed loop control; It is a direct linear or rotational detection device at the corresponding position of the final moving part of the machine tool, which feeds back the directly measured displacement or angular displacement value to the comparator of the numerical control device and compares it with the input command displacement, and controls the moving part with the difference value to make the moving part move strictly according to the actual displacement.
Performance classification of CNC machine tools
Economical CNC machine tools; Mid-range CNC machine tools; High-grade CNC machine tools;
According to the composition of the numerical control device used.
Hard wire numerical control system: soft wire numerical control system;
Edit the machining center
The first machining center was first developed by Carney-Tektronix in the United States in 1958. It adds a numerical control machine tool on the basis of a numerical control horizontal boring and milling machine.
The automatic tool changer is introduced, so that the centralized machining of milling, drilling, boring, reaming and tapping can be realized after the workpiece is clamped once. Machining center is a highly automated multifunctional CNC machine tool with tool magazine and automatic tool changing device. After the workpiece is clamped in the machining center once, more than two surfaces can be machined in various processes, and it has various functions of tool change or tool selection, which greatly improves the production efficiency. Machining centers can be divided into boring, milling and turning according to their processing technology, and can be divided into three-axis, four-axis and five-axis machining centers according to the number of control axes.
Edit this computer gong
Computer gong is also a kind of numerical control machine tool. Computer gong is actually a machining center, which is written in English as: CNC machining center; ; Computer gong is a common saying, which is called more frequently in Hongkong, Taiwan Province and Guangdong provinces. People in this area, when the milling machine is in the machining center, it is called gong, so the milling machine is also called gong bed, from which the computer gong comes. As the name implies, computer gong is a gong bed controlled by computer, so it is also called CNC milling. It is actually upgraded from a CNC milling machine, and the principle is the same. The difference is that the machining center has good materials, high precision, high speed, heavy load and improved appearance. Traditional NC milling is semi-covered. Computer gong is an automatic machine tool with program control system. This control system can use control codes or other symbolic instructions to logically process the program and decode it, so that the machine tool can move and process parts. Also called CNC or CNC machine tools. Computer gong can be divided into two parts: the main part and the system part. Body part: 1) Casting is the most important part of computer gong, which directly affects the accuracy, stability, wear resistance and the life of machine tools.
Life. After the casting is made, it is not immediately used for production. Good castings are weathered by wind and rain, sun and nature. Some are immersed in seawater until the castings remain unchanged before processing. The machine tool made in this way is not easy to deform and can maintain the stability and accuracy of the machine tool for a long time. 2) The spindle is used to directly face the workpiece to be processed and is driven by a motor to rotate at high speed. By installing the handle on the spindle, the machined workpiece can be cut to meet various production needs. The quality of the spindle will also directly affect the machining accuracy. If the internal bearing is worn, it is easy to cause the spindle to swing, and the accuracy of the processed things will naturally deviate from several threads. At present, the spindle speed is generally around 8000 rpm, and high-speed machines can achieve more than 20000 rpm. Each machine has only one spindle. 3) The lead screw is also a part of the machine body, driven by the servo motor, and the displacement of the workbench is driven by the copper sleeve of the lead screw to meet the processing needs. If there is a gap between the screws, it is also directly reflected in the machining accuracy and flatness. 4) motor. There are two kinds of motors: servo motors and variable frequency motors. Servo motor has good stability, high power of spindle drive motor and low coordination rate of three-axis drive motor. 5) Coupling: A coupling is installed between the screw and the motor, which is only used for linkage. 6) Lubrication cooling system consists of automatic oil pump, spindle oil cooler and chip liquid circulation system. Oil is automatically supplied, and oil can be pumped automatically without manual work. When the machine tool is working, oil is pumped every few minutes, and oil pipes are connected to all corners, such as screws and guide rails. If the oil pipe is blocked, the guide rail is easy to wear and the accuracy will be affected. Spindle oil cooling is a circulating cooling system for cooling the spindle. A spindle with 8000 revolutions is not necessary, and those with more than 8000 revolutions must be equipped. The cutting fluid circulation system pumps up the oil in the oil tank through the oil pump motor and rushes to the workpiece being processed. 7) Sheet metal, the requirements for sheet metal should not be too high, as long as there is no oil leakage, but it also involves the problem of beautiful appearance and image. System part: 1) display, now most of them are LCD color display. 2) Operation panel 3) Processor 4) The construction principle of the drive system is very complicated, but it is rarely broken. There are mainly Fanuc system in Japan, Mitsubishi system in Japan and Siemens in Germany. Wait a minute.
Edit the processing language of this paragraph.
It is divided into ATL language and NC language. ATL language produced by CAM software is an explanatory language to describe the tool path, which can be used in CAM software for line-by-line machining of machining centers.
Machining simulation. Numerical control language is produced by post-processor, which is the processing language actually input into machine tools. The NC program can also be written directly on the NC machine tool. There are mainly G code (machining code), M code (auxiliary function), T code (tool), S, F (spindle speed and chip cutting speed) and so on. The actual processing can be divided into online processing and ordinary processing. Ordinary machining is to use the existing numerical control program in the machine tool memory for machining, which can be continuous machining or single-step machining. On-line machining is to connect the computer to the machine tool and process directly. In this case, once an accident happens, it is difficult to react directly, so you can only press the emergency stop button.
Edit the technical development trend of this paragraph.
High-speed, precision, compound, intelligence and green are the general trends of NC machine tool technology development. In recent years, gratifying achievements have been made in practicality and industrialization. Mainly in: 1. Further development of machine tool compound technology With the technological progress of CNC machine tools, compound machining technology is becoming more and more mature, including milling-turning compound and turning-milling compound five-axis machining center.
Combination, turning-boring-drilling-gear machining, turning-grinding machining, molding machining and special machining greatly improve the precision and efficiency of compound machining. The concepts of "one machine tool is a processing factory" and "once loading the card and finishing the processing" are being accepted by more people, and the development of compound processing machine tools is showing a diversified trend. 2. The intelligent technology of CNC machine tools has made a new breakthrough, which is more reflected in the performance of CNC system. For example, the functions of interference automatic adjustment and anti-collision, power-off protection function of workpiece automatically exiting the safety zone after power-off, learning function of machining parts detection and automatic compensation, intelligent parameter selection function of high-precision machining parts, automatic elimination of machine tool vibration during machining and so on have entered the practical stage, and the function and quality of machine tools have been intelligently improved. 3. Robots make flexible combinations more efficient. The flexible combination of robot and host is widely used, which makes the flexible line more flexible, further expands its functions, further shortens the flexible line and improves its efficiency. Flexible units and flexible production lines such as robots and machining centers, turning-milling compound machine tools, grinders, gear machining machines, tool grinders, electric machining machines, sawing machines, punching machines, laser machining machines and water cutting machines have been applied. 4. New progress has been made in precision machining technology. The machining accuracy of CNC metal cutting machine tools has been improved from the original linear level (0.0 1mm) to the current micron level (0.00 1mm), and some varieties have reached about 0.05 micron. The micro-cutting and grinding accuracy of ultra-precision CNC machine tools can reach about 0.05μm, and the shape accuracy can reach about 0.01μ m. Through the optimization of machine tool structure design, ultra-precision machining and assembly of machine tool parts, and the adoption of high-precision closed-loop control and dynamic error compensation technology such as temperature and vibration, the geometric accuracy of machine tool machining is improved, and the form and position error and surface roughness are reduced, thus entering the era of ultra-precision machining in submicron and nanometer scale. 5. The performance of functional components is constantly improving. Functional components are constantly developing in the direction of high speed, high precision, high power and intelligence, and have achieved mature applications. The popularization and application of all-digital AC servo motor and driving device, high-tech motorized spindle, torque motor, linear motor, high-performance linear rolling assembly and high-precision spindle unit have greatly improved the technical level of CNC machine tools. Staff rating: mainly divided into junior technicians, ordinary technicians, senior technicians and senior technicians.
Edit this section of maintenance
Overview of CNC machine tool maintenance: prolong the life and wear cycle of parts, prevent all kinds of faults, improve the average trouble-free working time of CNC machine tools, and use CNC machine tools.
Life span. Problems needing attention in the use of NC machine tool 1. It is best to keep the use environment of CNC machine tools in a constant temperature environment, and stay away from equipment with large vibration (such as punching machines) and equipment with electromagnetic interference. 2. Power requirements 3. CNC machine tools should have regular maintenance procedures, and pay attention to record and protect the site when faults occur. 4. CNC machine tools should not be sealed for a long time. 5. Pay attention to training and equipping operators, maintenance personnel and programmers to maintain the numerical control system. 1. Strictly abide by the operating procedures and daily maintenance system. 2. Prevent dust from entering the numerical control equipment. Floating dust and metal powder can easily reduce the insulation resistance between components, leading to failure or even damage of components. 3. Regularly clean the cooling and ventilation system of the numerical control cabinet. 4. Regularly monitor the grid voltage of the numerical control system. The voltage range of the power grid is 85% ~ 1 10% of the rated value. 5. Replace the memory battery regularly. 6. Maintenance of the numerical control system when it is not used for a long time will often electrify the numerical control system or make the numerical control machine run the preheating program. 7. Repair spare circuit boards, mechanical parts and mechanical parts. 1. Maintenance of tool magazine and tool changing manipulator ① When manually loading tools into the tool magazine, make sure that they are in place and check whether the locking on the tool holder is reliable; (2) It is forbidden to load overweight and super-long tools into the tool magazine, so as to prevent the manipulator from dropping the tool or the tool colliding with the workpiece and fixture when changing the tool; numerical control machine
(3) When using the sequential tool selection method, we should pay attention to whether the order of the tools placed on the tool magazine is correct. Other tool selection methods should also pay attention to whether the tool change number is consistent with the required tool to prevent accidents caused by changing the wrong tool; (4) Pay attention to keep the handle and tool sleeve clean; ⑤ Always check whether the reset position of the tool magazine is correct, check whether the position of the tool changing point of the machine tool spindle is in place, and adjust it in time, otherwise the tool changing action cannot be completed; ⑥ When starting the machine, idle the tool magazine and the manipulator first, and check whether each part works normally, especially whether each travel switch and solenoid valve can work normally. 2. Maintenance of the ball screw pair ① Regularly check and adjust the axial clearance of the screw nut pair to ensure the reverse transmission accuracy and axial stiffness; (2) Regularly check whether the connection between the screw support and the lathe bed is loose and whether the support bearing is damaged. In case of the above problems, fasten the loose parts in time and replace the support bearing; ③ Use ball screw with grease, clean the old grease on the screw once every six months, and replace it with new grease. Ball screw lubricated with lubricating oil should be oiled once a day before the machine works; (4) When working, pay attention to avoid hard dust or debris from entering the screw shield and damaging the shield. If it is damaged, replace the protective device in time. 3. Maintenance of the main drive chain ① Regularly adjust the tightness of the spindle drive belt; ② Prevent all kinds of impurities from entering the oil tank. Change the lubricating oil once a year; ③ Keep the joint between spindle and tool rest clean. Adjust the displacement of hydraulic cylinder and piston in time; ④ Adjust the counterweight in time. 4. Hydraulic system maintenance ① Regularly filter or replace the oil; ② Control the oil temperature in the hydraulic system; ③ Prevent the hydraulic system from leaking; (4) regularly check and clean the oil tank and pipeline; ⑤ Implement the daily inspection system. 5. Maintenance of pneumatic system ① Remove impurities and moisture from compressed air; (2) Check the oil supply of the oil mist device in the system; ③ Keep the system airtight; (4) Pay attention to adjusting the working pressure; ⑤ Clean or replace pneumatic components and filter elements; Actual maintenance of CNC machine tools 1. Learn more 1. Read more numerical control materials to understand the characteristics and functions of various numerical control systems and PLC programmable controllers. Understand the alarm and elimination methods of numerical control system; Understand the significance of parameter setting of CNC and PLC machine tools; Understand the programming language of PLC; Understand the method of numerical control programming; Understand the operation of the control panel and the contents of each menu; To understand the performance of spindle and feed motor and the characteristics of driver, a lot of numerical control data are often needed. what do you think? I think it is very important to highlight the key points and clarify the context. The key point is to thoroughly understand the basic composition and structure of CNC system and master the block diagram. The rest can be read through, but each part should be understood and mastered. Because the internal wiring diagram of CNC system is quite complicated, the manufacturer does not provide it. So there is no need to elaborate. For example, NX- 154 four-axis five-linkage blade processing machine adopts A-B 10 system, so it is necessary to focus on the functions of each part, the functions of each board, the direction of interface, the meaning of LED lights and so on. Nowadays, there are many types of numerical control systems, which can be updated quickly. Different manufacturers and models often vary greatly. To understand its * * * and personality (particularity). Generally, people who are familiar with the maintenance of Siemens CNC system are not necessarily skilled in troubleshooting A-B system, so they should read more books and constantly learn and update their knowledge. 2. Read more electrical diagrams and digest them. For each electrical component, such as contactor, relay, time relay, PLC input and output, it should be marked one by one on the electrical diagram. For a simple example, for example, 1A 1 is a contactor started by hydraulic pump motor 1M, and the direction of its normally open and normally closed contacts is generally indicated on the drawing. Therefore, the normally open or normally closed contact 1A 1 on the corresponding page can be marked with the content that the hydraulic pump motor is turned on. The electrical diagram of a large CNC machine tool has dozens or even hundreds of pages. It takes a long time to understand the function of each component. Sometimes once or twice, you may not know the function of this part, so you should look at the CNC machine tool more.
Let's wait until we digest it later. Therefore, the startup of the hydraulic pump motor 1M mentioned just now should also clearly indicate which external output of PLC drives the contactor 1A 1, and the context should be clear. However, some block diagrams in the electrical wiring diagram, such as the drivers of each shaft, are just a block diagram. As long as you know some control conditions (on-off conditions), you can study things that consider details when you have time. The electrical symbols in different countries are different, so we must first understand them clearly. For several thick PLC statement tables written by manufacturers, we should also read more, master its programming language, and make Chinese comments and translations on the basis of understanding. This can greatly save the time of troubleshooting in the future. If you wait for the fault to get familiar with the electrical diagram and PLC statement table, it will take a lot of time and often lead to wrong judgment. 3. Read more hydraulic and pneumatic diagrams, thoroughly digest the mechanical, hydraulic and pneumatic diagrams of CNC machine tools, and understand their functions and context. And note on the drawings one by one, for example, the installation of accessories and tools for CNC gantry milling in Coburg, Germany is complicated, and the drawings need to be decomposed, such as which solenoid valve is used to lock the tools? What are the corresponding PLC outputs and inputs? The drawings indicate that electrical and mechanical actions should be carried out to the end, and at the same time, the parts closely related to machinery and electricity should be emphasized. For example, Italy INNSE CNC milling machine adopts electro-hydraulic proportional valve technology, and its function and function, especially its adjustment method and data, should be emphasized. It is necessary to know the current of proportional valve and the corresponding pressure of balance pump under static and dynamic conditions, and master the problem-solving skills. 4. Read more foreign languages and improve your professional foreign language reading ability. You don't know foreign languages, especially English. It is impossible to understand a large number of foreign technical materials, and it is often not ideal to rely solely on translation. It is difficult to read the technical materials in foreign languages at first, and there are many new words. Read more and remember more, so many commonly used professional words, and it will be easy to read in the future. A competent maintainer should basically master language tools. Ask more questions 1. Ask more foreign experts. If you have the opportunity to go abroad for training or foreign experts come to your factory to install and debug machine tools, you'd better have the opportunity to participate. This is the best learning opportunity, because you can get a lot of first-hand information, as well as the methods and skills of machine tool debugging. For example, how to correct electricity after laser measuring the accuracy of each axis. Ask more questions and find out what you don't understand. Through this period of time, there will be great gains, and many internal materials and manuals can be obtained (confidential to users). When machine tools are put into formal production, we should always keep close contact with relevant foreign experts. Through fax and E-MALL, it is very beneficial to ask for further solutions and related materials, solve the difficult faults of machine tools, and get special and special spare parts. At the same time, we should also keep good relations with the agents of CNC systems such as Siemens and FANUC, ask more questions, get further information and related spare parts of CNC systems in time, and also have the opportunity to take special courses on CNC systems. 2. After a fault occurs, ask the operator's master about the whole process of the fault. Don't ask, or just ask, so you often can't get the correct on-site information, which will lead to wrong judgment and complicate the problem. Therefore, we should ask more questions and ask in detail to understand the whole process of the fault (beginning, middle and end), which alarm signals were generated, which components were operated at that time, which components were touched, and how to correct them. On the basis of fully investigating the site and mastering the first-hand information, the fault problems are listed correctly, and half of the problems have actually been solved, and then analyzed and solved. For experienced and skilled operators, it is very beneficial to be familiar with machine tool operation, processing procedures and common diseases of machine tools, and to work closely with them to quickly troubleshoot. 3. Ask other maintenance personnel. Other maintenance personnel are repairing machine tools. When you are away, when they come back, you should also ask more, what happened just now? How did he rule it out? Ask him to introduce its elimination method. This is also a good learning opportunity. Learn from other people's correct troubleshooting skills and methods, especially from experienced old maintenance personnel, learn their skills and improve their knowledge and level.