CNC milling machine is a kind of CNC machine tool with powerful machining function. At present, the rapid development of machining centers and flexible machining units are based on CNC milling machines and CNC boring machines, both of which are inseparable from milling methods. Because the process of NC milling is the most complicated and there are the most technical problems to be solved, people have always focused on milling when researching and developing NC system software and automatic programming language.
The CNC milling machine adopts electric spindle, which improves the dynamic response speed and working accuracy of the spindle and completely solves the vibration and noise problems of belt and pulley transmission when the spindle runs at high speed. The milling machine adopts electric spindle structure, which can make the spindle speed reach above 10000r/min. Choose the electric spindle of milling machine and find Taihao machinery to ensure professional quality; Linear motor has high driving speed, good acceleration and deceleration characteristics, excellent response characteristics and following accuracy. The linear motor is used as the servo drive, which saves the intermediate transmission link of the ball screw, eliminates the transmission gap (including the reverse gap), has small inertia, good system rigidity, can accurately position at high speed, and greatly improves the servo accuracy.
Electric spindle is a new technology that combines spindle and spindle motor in the field of CNC machine tools in recent years. Together with linear motor technology and high-speed tool technology, it will push high-speed machining to a new era. The motorized spindle is a set of components, including the motorized spindle itself and its accessories: motorized spindle, high-frequency frequency conversion device, oil mist lubricator, cooling device, built-in encoder and tool changing device.
Electric spindle integration technology;
High-speed bearing technology: the motorized spindle usually adopts composite ceramic bearings, which are wear-resistant and heat-resistant, and their service life is several times that of traditional bearings; Sometimes electromagnetic bearings or hydrostatic bearings are used, and the inner and outer rings are not in contact, so the service life is infinite in theory;
High-speed motor technology: motorized spindle is the product of the integration of motor and spindle, and the rotor of motor is the rotating part of spindle. Theoretically, the motorized spindle can be regarded as a high-speed motor. The key technology is high-speed dynamic balance;
Lubrication: the lubrication of motorized spindle generally adopts periodic quantitative oil-gas lubrication; It can also be lubricated with grease, but the corresponding speed should be discounted. The so-called timing means spraying oil every once in a while. The so-called quantification is to accurately control the amount of lubricating oil each time through a device called a quantitative valve. Oil-gas lubrication is to blow lubricating oil into ceramic bearings with the help of compressed air. Oil quantity control is very important, too little, and it can't play a lubricating role; Too much, the bearing will heat up due to the resistance of oil when it rotates at high speed.
Cooling device: In order to dissipate heat for high-speed motorized spindle as soon as possible, circulating cooling liquid is usually introduced into the outer wall of motorized spindle, and the function of cooling device is to keep the temperature of cooling liquid.
Built-in pulse encoder: In order to realize automatic tool change and rigid tapping, the motorized spindle has built-in pulse encoder to realize accurate phase angle control and cooperation with feed.
Automatic tool changing device: in order to be used in machining center, the motorized spindle is equipped with automatic tool changing device, including disc spring, broach cylinder and so on.
Clamping method of high-speed tools: The well-known BT and ISO tools have been proved to be unsuitable for high-speed machining. In this case, HSK, SKI and other high-speed tools appeared.
High-frequency frequency conversion device: To realize the rotating speed of the motorized spindle of tens of thousands or even hundreds of thousands of revolutions per minute, the high-frequency frequency conversion device must be used to drive the high-speed motor built in the motorized spindle, and the output frequency of the frequency converter must reach several thousand or several thousand hertz.
The motorized spindle consists of a shell-less motor, a spindle, a bearing, a spindle unit shell, a driving module and a cooling device. The rotor of the motor is integrated with the main shaft through press fitting, and the main shaft is supported by front and rear bearings. The milling machine electric spindle manufacturer looks for Taihao machinery, and the motor stator is installed in the spindle unit shell through the cooling jacket. The speed change of the spindle is controlled by the spindle drive module, while the temperature rise in the spindle unit is limited by the cooling device. The sensor for measuring speed and angular displacement is installed at the rear end of the spindle, and the inner cone hole and end face at the front end are used to install the cutter.
The rotor of the motor directly serves as the spindle of the machine tool, and the shell of the spindle unit is the motor base, which cooperates with other components to realize the integration of the motor and the spindle of the machine tool. With the rapid development and perfection of electric drive technology (frequency conversion speed regulation technology, motor vector control technology, etc.). ), the mechanical structure of the main drive system of high-speed CNC machine tools is greatly simplified, and the pulley drive and gear drive are basically cancelled. The spindle of the machine tool is directly driven by the built-in motor, thus shortening the length of the main transmission chain of the machine tool to zero and realizing the "zero transmission" of the machine tool. This transmission structure of spindle motor and machine tool spindle "combined into one" makes the spindle parts relatively independent of the transmission system and overall structure of the machine tool, so it can be made into "spindle unit", commonly known as "electric spindle". At present, the motorized spindle mainly adopts AC high frequency motor, so it is also called "high frequency spindle". Because there is no intermediate transmission link, it is sometimes called "direct drive spindle".
Milling machine mainly refers to the machine tool that uses milling cutter to process various surfaces of workpiece. Usually, the milling cutter is mainly rotating, and the movement of the workpiece and milling cutter is feeding. Can process planes and grooves, as well as various curved surfaces and gears.
Milling machine is a machine tool for milling workpieces with milling cutter. Milling machines can not only mill planes, grooves, gear teeth, threads and spline shafts, but also process more complex contours, with higher efficiency than planers, and are widely used in machinery manufacturing and repair departments.
Milling machine is a widely used machine tool, which can process plane (horizontal plane, vertical plane), groove (keyway, T-groove, dovetail groove, etc. ), toothed parts (gears, spline shafts, sprockets), helicoids (threads, spiral grooves) and various curved surfaces. In addition, it can also be used to process the surface and inner hole of the rotary body and cut it off. When the milling machine is working, the workpiece is mounted on the accessories such as the workbench or the indexing head, and the rotation motion of the milling cutter is the main motion, supplemented by the feeding motion of the workbench or the milling head, so that the workpiece can obtain the required machining surface. Because it is multi-edge intermittent cutting, the productivity of milling machine is high. Simply put, a milling machine is a machine tool that can mill, drill and bore a workpiece.
CNC milling machine is also called CNC milling machine. Milling machine controlled by digital signal of electronic instrument. CNC milling machine is an automatic processing equipment developed on the basis of ordinary milling machine. Their processing technology is basically the same, and their structures are somewhat similar. CNC milling machines can be divided into two categories: tool magazine and tool magazine. Among them, the CNC milling machine with tool magazine is also called machining center.
In addition to the characteristics of ordinary milling machine, CNC milling has the following characteristics:
1, parts have strong processing adaptability and good flexibility, and can be used to process parts with particularly complex contour shapes or difficult to control dimensions, such as mold parts and shell parts;
2. It can process parts that ordinary machine tools can't process or are difficult to process, such as complex curve parts and three-dimensional curved parts described by mathematical models;
3. Parts requiring multiple processes can be processed by one-time clamping and positioning;
4. The machining accuracy is high, and the machining quality is stable and reliable. The pulse equivalent of the numerical control device is generally 0.00 1mm, and the high-precision numerical control system can reach 0.1m. In addition, the numerical control processing also avoids the operator's operation mistakes.
5. The high degree of production automation can reduce the labor intensity of operators. Conducive to the automation of production management;
6, high production efficiency, CNC milling machines generally do not need to use special process equipment such as special fixtures, and only need to call the processing program stored in the CNC device, clamp the tool and adjust the tool data when replacing the workpiece, thus greatly shortening the production cycle. Secondly, the CNC milling machine has the functions of milling machine, boring machine and drilling machine, which makes the working procedures highly concentrated and greatly improves the production efficiency. In addition, the spindle speed and feed speed of CNC milling machine are stepless, which is beneficial to choose the best cutting parameters;
Because the CNC machine tool adopts servo motor, the digital technology is applied to realize the direct control of the working sequence and movement displacement of the executive parts of the machine tool, and the gearbox structure of the traditional machine tool is cancelled or partially cancelled, thus greatly simplifying the mechanical structure. Digital control also requires the mechanical system to have high transmission stiffness and no transmission clearance to ensure the execution of control instructions and the realization of control quality. At the same time, due to the continuous improvement of computer level and control ability, it is possible for more functional components to perform various auxiliary functions on the same machine tool at the same time. Therefore, the mechanical structure of CNC machine tools requires higher integrated functions than traditional machine tools. From the requirements of manufacturing technology development, with the emergence of new materials and new processes, as well as the requirement of low cost in market competition, metal cutting is developing towards higher cutting speed and accuracy, higher production efficiency and more reliable system. This requires that the CNC machine tools developed on the basis of traditional machine tools have higher precision, higher driving power, better static and thermal stiffness of mechanical mechanisms, more reliable work, long-term continuous operation and as little downtime as possible.
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