China's numerical control development briefs Since the reform and opening up, China's numerical control technology development research has developed rapidly, especially after the "sixth five-year" (1981 ~ 1985) planning to introduce foreign technology, "seventh five" (1986 ~ 1990) planning The introduction and extraction of technology, the "Eighth Five-Year Plan" (1991-1995) was planned by the state organization of scientific and technological research on the development of independent copyright NC and the "Ninth Five-Year Plan" (1996-2000) planning national organization industrialization and other stages of implementation, developed There are two basic systems (ie platforms) with independent copyrights in China, four CNC systems and their derivatives. They are China I (China Everest), Aerospace Type I (Aerospace Numerical Control Group), Blue Sky I (Shenyang Institute of Computing, Chinese Academy of Sciences), and Huazhong I (Huazhong University of Technology). Among them, Zhonghua I and Huazhong I are developed based on PC+ CNC card hardware platform. Aerospace Type I is designed with a PC compatible with a general-purpose PC, plus a CNC universal/dedicated template to form a stand-alone CNC system. On this basis, it is interconnected with a general-purpose PC to form a typical Multi-machine system with front/backstage structure. The Blue Sky I type is based on the high-end CNC of the original 7500 series. It is secondarily integrated by a large-scale programmable gate array chip (EPLD). After the design is reduced, it is interconnected with a general-purpose PC to form an 8500 series multi-machine system. The successful development of these high-grade CNC systems has made great progress in China's numerical control technology, and it has brought new opportunities to the development of CNC in China. Now with the rapid development of chip technology and computer systems, the open architecture is designed by using general-purpose microcomputer systems. The CNC system has transferred development work to software and algorithms, and has made breakthroughs in the four basic systems that have been developed.

The above-mentioned high-end CNC system has multi-axis linkage function, and the number of linkage axes can be more than five axes. This shows that in the development of the new generation CNC system, we have stood on the same starting line with foreign countries and completely changed the CNC machine tool equipment in China. The CNC system has long been dependent on foreign countries, and the development of high-end CNC system has also provided a strong guarantee for the development of high-end CNC machine tools in China. Now, we have been able to develop various types of CNC systems required for domestic CNC machine tools. Domestic CNC system, whether it is economical numerical control, or popular (mid-range CNC) and advanced (high-grade CNC), has entered the production of medium and small batches in recent years and has been widely used. Of course, economical numerical control is still the largest system in China. In the past 10 years, more than 20,000 ordinary machine tools have been transformed into economical CNC machine tools (mainly lathes). The use of popular and high-grade CNC systems for ordinary machine tools and traditional machine tools, the transformation of imported machine tools and technically aging machine tools or used machine tools, in recent years also has significant economic benefits, such as: Blue Sky high-grade CNC National Engineering Research Center, in batch On the basis of production, more than 200 high-end and medium-sized CNC products and machine tools have been supplied to the machine tool industry, not only with more than 20 CNC machine tools, machining centers, turning centers, CNC lathes, CNC milling machines, etc. The machine tool is matched, and it also supports and completes the matching and research of the national major CNC machining equipment. The blue sky high-grade CNC system was also successfully equipped with the “S3FMC01 disk-type flexible manufacturing unit” of Shenyang No.3 Machine Tool Plant, and the first Shenyang-based machine tool factory was successfully equipped with the first dual-process crankshaft milling machine in China, which cooperated with the Changchun Institute of Optics and Mechanics of the Chinese Academy of Sciences. Equipped with China's first CNC aspherical optical lens processing center and so on. In another example, Huazhong CNC Company has carried out numerical control transformation on dozens of key equipments of 10 heavy-duty machine tools and medium-sized machine tools and other enterprises in Dongfang Electric Machinery Factory (a key enterprise in domestic large-scale power generation equipment manufacturing), making it a popular type. Advanced CNC machine tools.

What is even more gratifying is that the high-end CNC system (NC-100 system) jointly developed by the advantage of the high-end CNC system of the high-end CNC National Engineering Research Center and the servo system of Beijing Kaiqi CNC Equipment Co., Ltd. has been successfully Foreign exports began to export 80 sets to Russia in 1998, realizing the turning point of domestic CNC system from import to export. It marks that the technical level of China's high-end CNC system has reached a new stage of participating in the international market competition, and it is a qualitative leap in the development of China's CNC system technology.

At present, China's numerical control technology has a considerable turn in the new generation of open control systems based on PC. The four basic types of successful development have their own advantages. However, as far as the openness is concerned, they do not yet have the essential characteristics of an open control system. The architectures adopted by each system are inconsistent. The platform problems of open control systems have not been solved, and there is a lack of compatibility and interchangeability between them. .

Obviously, the software and hardware of the system are still not portable and interoperable. From the perspective of software development, it is only at the level of structured programming, and no further use of object-oriented, software reuse, secondary development and other software projects. New technologies have made the openness of application systems far from the requirements of open control systems. Therefore, in the further development of China's numerical control technology, on the basis of the general PC system architecture, it is particularly important to formulate the technical specifications of the open CNC system.

In view of the status quo and problems of developing open CNC systems at home and abroad, some colleges and universities in China have carried out active research and development work. The Institute of Production Systems and Control of Shanghai Jiaotong University uses general-purpose microcomputers as numerical control platforms to develop their own software. Advantages, establish a standardized application interface, a unified real-time communication system, a dynamic real-time configuration system as the main content of the system platform and a functional element-based system reference structure, directly improve the adaptability of the CNC system to different needs, standardize The implementation mode of the system has been well applied to the transformation of CNC lathes.

The development trend of numerical control technology Currently, numerical control technology mainly presents the following development trends: 1 High-precision, high-speed, high-efficiency processing In the gold cutting process, CNC machine tools are already the key equipment for semi-finishing and finishing. In order to further improve the precision, in addition to ensuring the geometric precision and good structural characteristics of CNC machine tool manufacturing, it can be realized by reducing the error of the numerical control system and adopting certain compensation techniques. At the same time, it must have a high-precision position detection system and high-performance servo. system. The development of a high-performance numerical control system and an all-digital servo system with a pulse equivalent of 0.1μ (an order of magnitude higher than that of the existing CNC system) will directly promote the positioning accuracy and machining accuracy of CNC machine tools, and become super An indispensable control device in finishing technology. Increasing productivity is one of the basic goals pursued in the development of CNC machining technology. First, it is necessary to increase the cutting speed and feed rate, and also reduce the auxiliary time and shorten the non-cutting time. Specifically, it is to increase the spindle speed (this is the most direct and effective way to increase the cutting speed), improve the rapid movement speed of each coordinate axis (ie feed rate), and shorten the tool change time (in the automatic tool exchange in the machining center) And the time of the workbench exchange (automatic exchange workbench in the FMC).

For the spindle speed, it was generally 4000 ~ 6000R / min in the mid-1980s, and entered 8000 ~ 12000R / min later, since the 1990s, there have been 12000 ~ 50000R / min and even ultra-high speed (more than 50000R / min) processing The center machine tool appeared, for example, the VZ40 vertical machining center of Niigata Iron Works, Japan, with a spindle speed of up to 50000R/min. Using this machine tool, combined with ceramic tools, it takes only 12 to 13 minutes to process NAC55 steel molds, and 9 hours on ordinary machine tools. Only after completion, it is clear that high-speed cutting brings efficient machining.

According to the development of servo system, the rapid movement speed of each coordinate axis has been increased from 15~24m/min 10 years ago to 30~40m/min now, with high-performance CNC system and superior Linear motor drive with acceleration and deceleration characteristics. On heavy-duty or large-scale CNC machine tools, high-speed idle travel can reach more than 40m/min to 100m/min, which greatly reduces non-cutting time.

The rapid tool change of the machining center and the shortened workbench exchange time on the FMC have also made great progress in recent years. Through the improvement of the tool change mechanism, the tool change time is reduced from 5 to 10 s to 2 to 4 s, and some even reach 0.5 to 1 s. The work table exchange time is also reduced from the past 12 to 20 s to 6 to 10 s. It can be reached within 2.5s, which minimizes the auxiliary time.

The reliability of high-reliability CNC systems is a key indicator of the quality of CNC machine tools and is often measured by MTBF (mean time between failures). With the improvement of component integration, the reliability index MTBF has been increased from 10000h in the 1980s to 30,000~50000h in the 1990s. The new generation of CNC-based CNC system has been successfully developed, and its reliability index MTBF has reached 10 More than a year.

Enhance the ability of communication networking. Develop multiple communication interfaces and multi-level communication functions on the CNC system to meet the different needs of incoming and networking, so that it not only has point-to-point communication such as serial and DNC, but also supports Manufacturing Automation Protocol (MAP) and A variety of general-purpose and dedicated network operations such as Ethernet have become the basic equipment for factory automation.

Strengthening standardization and openness In order to make PC-based open CNC system become an important wing of CNC technology development, to form an industry and continuously adapt to the needs of manufacturing development, it is necessary to formulate necessary technical specifications on the basis of the general PC architecture. According to the requirements of modern control systems, the hardware architecture and functional modules are compatible, and the software hierarchy, control flow, interface and module structure are standardized and standardized, providing a good openness and development environment for machine tool manufacturers or users. .

Network numerical control networked numerical control is the development of numerical control to the general computer, that is, the open architecture. Under the open architecture standard, the network technology is applied to establish an open system with network communication function and unified software and hardware platform structure. Enhanced network functions can realize network manufacturing, off-site manufacturing, remote diagnosis and maintenance, strengthen the transmission and management of processing information by the factory, improve the degree of machining automation and remote monitoring, and the manufacturer can diagnose the CNC system through the WAN or telephone network. And maintenance.

The intelligent degree of intelligent CNC system is closely related to the development of artificial intelligence technology and computer application, and it is almost included in all aspects of CNC system: in order to improve the quality of processing and processing efficiency, adaptive control technology is used to detect necessary from processing. Information to automatically adjust system related parameters, improve system operation status, and achieve optimal operation. The expert system was introduced to establish a process parameter database to support the processing. For example, fuzzy logic control for electric machine tools and a neural network system with self-learning function have been developed. With intelligent digital servo drive, application of feedforward control, adaptive calculation of motor parameters, automatic identification of load, automatic adjustment of parameters, etc. to improve servo system performance. From conversational programming to shop-oriented programming and intelligent automatic programming and from touch screen operation, to the introduction of "fool" system and intelligent human-machine interface, the CNC system is simplified in simplifying programming and simplifying operation. process. Finally, the application of distributed artificial intelligence (DAI) technology and the development of intelligent detection and monitoring systems with Agent (Intelligent Body) elements will greatly enhance the degree of intelligence of the CNC system.

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