CNC machine tool is the mainstream equipment of modern manufacturing industry, the necessary equipment for precision machining, is an important symbol of modern machine tool technology level and modern machinery manufacturing technology level, and is a strategic material related to the national economy and people's livelihood, and national defense cutting-edge construction. Therefore, the developed countries in the world have taken important measures to develop their own CNC technology and industry.
CNC is the abbreviation of computer numerical control, which means "computer data control". In a word, it means "numerical control processing". In the Pearl River Delta region, people call it "computer gong".
NC machining is an advanced machining technology in today's mechanical manufacturing. It is an automatic processing method with high efficiency, high precision and high flexibility. It is to input the NC program of the workpiece to be processed into the machine tool. Under the control of these data, the machine tool can automatically process the workpiece in line with people's wishes, so as to produce wonderful products.
Development trend of CNC machine tools
1. High speed
With the rapid development of automobiles, national defense, aviation, aerospace and other industries, as well as the application of aluminum alloy and other new materials, the requirement of high-speed CNC machining is higher and higher.
a. Spindle speed: the machine tool adopts motorized spindle (built-in spindle motor), and the maximum spindle speed is 200000r / min;
b. Feed rate: when the resolution is 0.01 μ m, the maximum feed rate can reach 240m / min, and the complex precise machining can be obtained;
c. Operation speed: the rapid development of microprocessors provides guarantee for the development of CNC system to high speed and high precision. The development of CNC system with CPU has developed to 32-bit and 64 bit, and the frequency has increased to hundreds of MHz and up to gigahertz. Due to the great improvement of operation speed, the feed rate of 24-240m / min can be obtained when the resolution is 0.1 μ m and 0.01 μ M;
d. Tool change speed: at present, the tool exchange time of foreign advanced machining centers is generally around 1s, and the high tool exchange time has reached 0.5s. Chiron company of Germany designs the tool magazine as basket style, with the spindle as the axis, and the tool is arranged in the circumference. The tool change time from tool to tool is only 0.9s.
2. High precision
The accuracy requirements of CNC machine tools are not limited to the static geometric accuracy. More and more attention has been paid to the motion accuracy, thermal deformation and vibration monitoring and compensation.
a. To improve the control accuracy of CNC system: high speed interpolation technology is adopted to realize continuous feed with micro program segment to refine CNC control unit. High resolution position detection device is used to improve position detection accuracy. Feed forward control and nonlinear control are used in position servo system;
b. Error compensation technology: reverse clearance compensation, screw pitch error compensation and tool error compensation are used to comprehensively compensate the thermal deformation error and spatial error of the equipment.
c. The grid decoder is used to check and improve the motion track accuracy of the machining center: the machining accuracy of the machine tool is predicted by simulation to ensure the positioning accuracy and repeated positioning accuracy of the machine tool, so that its performance is stable for a long time, and can complete a variety of processing tasks under different operating conditions, and ensure the processing quality of parts.
3. Function compounding
The meaning of compound machine tool is to realize or complete the processing of multiple elements from blank to finished product on one machine tool. According to its structural characteristics, it can be divided into two types: process compound type and process compound type. The machining center can complete turning, milling, drilling, hobbing, grinding, laser heat treatment and other processes, and can complete all the processing of complex parts. With the continuous improvement of modern machining requirements, a large number of multi axis CNC machine tools are more and more welcomed by major enterprises.
4. Intelligent control
With the development of artificial intelligence technology, in order to meet the development needs of manufacturing flexibility and manufacturing automation, the intelligent degree of CNC machine tools is constantly improving. It is embodied in the following aspects:
a. Adaptive control technology of machining process;
b. Intelligent optimization and selection of machining parameters;
c. Intelligent fault self diagnosis and self repair technology;
d. Intelligent fault playback and fault simulation technology;
e. Intelligent AC servo drive device;
f. Intelligent 4m numerical control system: in the manufacturing process, the measurement, modeling, processing and machine operation are integrated into one system.
5. Open system
a. Open to the future technology: since the software and hardware interfaces follow the recognized standard protocol, the new generation of general hardware and software can be adopted, absorbed and compatible.
b. Open to users' special requirements: update products, expand functions, provide various combinations of hardware and software products to meet special application requirements;
c. Establishment of numerical control standard: standardized programming language is not only convenient for users, but also reduces labor consumption directly related to operation efficiency.
6. Drive parallelization
It can realize multiple functions of multi coordinate linkage NC machining, assembly and measurement, and can better meet the processing of complex special parts. Parallel machine tool is considered as "the most significant progress in machine tool industry since the invention of CNC technology" and "a new generation of CNC processing equipment in the 21st century".
7. Extreme (large scale and miniaturization)
The development of national defense, aviation and aerospace and the large-scale of energy and other basic industrial equipment need the support of large-scale and good performance CNC machine tools. Ultra precision machining technology and micro nano technology are the strategic technologies in the 21st century. It is necessary to develop new manufacturing technology and equipment that can adapt to the micro size and micro nano machining accuracy.
8. Information interaction networking
It can not only realize the sharing of network resources, but also realize the remote monitoring, control, remote diagnosis and maintenance of CNC machine tools.
9. Green processing
In recent years, there are more and more energy-saving and environment-friendly machine tools with no or less use of coolant to achieve dry cutting and semi dry cutting. The trend of green manufacturing accelerates the development of various energy-saving and environmental protection machine tools.
10. Application of multimedia technology
Multimedia technology integrates computer, audio-visual and communication technology, so that the computer has the ability to deal with sound, text, image and video information. It can be used in real-time monitoring system, fault diagnosis of production field equipment and monitoring of production process parameters, so it has great application value.
At present, the development of CNC machine tools is changing with each passing day. High speed, high precision, compound, intelligent, open, parallel driven, networked, extreme and green have become the development trend and direction of CNC machine tools.