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Numerical control technology is a technology that uses digital information to control mechanical movement and working process. Numerical control equipment is a mechatronics product formed by the penetration of new technologies represented by numerical control technology into traditional manufacturing industries and emerging manufacturing industries, so-called digital equipment. Its technical scope covers many fields: (1) mechanical manufacturing technology; (2) information processing, processing, transmission technology; (3) automatic control technology; (4) servo drive technology; (5) sensor technology; (6) software Technology, etc.
First, the development trend of numerical control technology
The application of numerical control technology not only brought revolutionary changes to the traditional manufacturing industry, but also made the manufacturing industry a symbol of industrialization. With the continuous development of numerical control technology and the expansion of application fields, he has some important industries (IT, automobile) for the national economy and the people's livelihood. The development of light industry, medical care, etc. plays an increasingly important role, because the digitization of the equipment required in these industries is a major trend in modern development. Judging from the current trends in the development of CNC technology and its equipment in the world, its main research hotspots are as follows.
1. New trends in high-speed, high-precision machining technology and equipment
Efficiency and quality are the mainstays of advanced manufacturing technology. High-speed, high-precision machining technology can greatly improve efficiency, improve product quality and grade, shorten production cycle and improve market competitiveness. To this end, the Japan Advanced Technology Research Association listed it as one of the five modern manufacturing technologies, and the International Society of Production Engineering (CIRP) identified it as one of the central research directions of the 21st century.
In the car industry, the annual production cycle of 300,000 units is 40 seconds per vehicle, and multi-variety processing is one of the key issues that must be solved in car equipment; in the aerospace and aerospace industries, the parts processed are mostly thin-walled. And thin ribs, the rigidity is very poor, the material is aluminum or aluminum alloy, and these ribs and walls can be processed only when the cutting speed and cutting force are small. Recently, a large-scale aluminum alloy blank "hollowing" method has been used to manufacture large parts such as wings and fuselages to replace multiple parts by assembling numerous rivets, screws and other joints, so that the strength, rigidity and reliability of the components are obtained. improve. These all require high speed, high precision and high flexibility for processing equipment.
From the situation of EMO2001, the feed rate of high-speed machining center can reach 80m/min or even higher, and the idle speed can reach about 100m/min. At present, many automobile factories in the world, including Shanghai General Motors Co., Ltd. of our country, have already replaced the combination machine tools with a production line composed of high-speed machining centers. The CINCINNATI HyperMach machine has a feed rate of up to 60m/min, a fast speed of 100m/min, an acceleration of 2g and a spindle speed of 60,000r/min. It takes only 30 minutes to process a thin-walled aircraft part, and the same part takes 3 hours for general high-speed milling machine and 8 hours for ordinary milling machine. The spindle speed and acceleration of German DMG double-spindle lathe are 12*!000r/mm respectively. And 1g.
In terms of machining accuracy, in the past 10 years, the machining accuracy of ordinary CNC machine tools has been increased from 10μm to 5μm, and precision machining centers have been improved from 3 to 5μm to 1 to 1.5μm, and ultra-precision machining accuracy has begun to enter the nanometer class. (0.01 μm).
In terms of reliability, the MTBF value of foreign numerical control devices has reached more than 6 000h, and the MTBF value of the servo system has reached more than 30,000h, showing very high reliability.
In order to achieve high-speed, high-precision machining, the functional components such as electric spindles and linear motors have been rapidly developed, and the application fields have been further expanded.
2. Rapid development of 5-axis simultaneous machining and compound machining machines
The 5-axis joint machining of the 3D curved parts can be performed with the best geometry of the tool, which not only has a high finish, but also greatly improves the efficiency. It is generally believed that the efficiency of a 5-axis linkage machine can be equal to two 3-axis linkage machines. Especially when using high-hardness milling cutters such as cubic boron nitride for high-speed milling of hardened steel parts, 5-axis linkage machining can be linked with 3 axes. Processing has a higher efficiency. However, in the past, due to the 5-axis linkage CNC system and the complicated structure of the mainframe, the price is several times higher than that of the 3-axis linkage CNC machine tool. In addition, the programming technique is difficult, which restricts the development of the 5-axis linkage machine tool.
At present, due to the emergence of the electric spindle, the structure of the composite spindle head for 5-axis simultaneous machining is greatly simplified, the manufacturing difficulty and cost are greatly reduced, and the price gap of the numerical control system is narrowed. Therefore, the development of the composite spindle head type 5-axis linkage machine tool and the composite machining machine tool (including the 5-face machining machine tool) has been promoted.
At EMO2001, the 5-day machining machine of Nippon Machine Co., Ltd. uses a composite spindle head to realize four vertical plane machining and machining at any angle, so that 5-sided machining and 5-axis machining can be realized on the same machine. Machining of inclined faces and inverted tapered holes is possible. DMG of Germany exhibited the DMUVoution series of machining centers, which can be processed in 5 sides and 5 axes in one setup, and can be controlled directly or indirectly by CNC system control or CAD/CAM.
3. Intelligent, open and networked become the main trend of the development of contemporary CNC systems
The 21st century CNC equipment will be a certain intelligent system. The intelligent content includes all aspects in the CNC system: for the pursuit of processing efficiency and processing quality, such as adaptive control of the process, automatic process parameters Generated; intelligent to improve drive performance and convenient connection, such as feedforward control, adaptive calculation of motor parameters, automatic identification of load automatic selection model, self-tuning, etc.; simplify programming, simplify operation, intelligent, such as intelligence Automatic programming, intelligent human-machine interface, etc.; as well as intelligent diagnosis, intelligent monitoring, and convenient system diagnosis and maintenance.
In order to solve the problems of the traditional CNC system closure and the industrial production of CNC application software. At present, many countries have researched open CNC systems, such as The Next Generation Work-Station/Machine Control (NGC), OSACA (Open System Architecture for Control within Automation Systems), and OSEC (Open System Environment) in Japan. For Controller), China's ONC (Open Numerical Control System) and so on. The openness of CNC systems has become the future of CNC systems. The so-called open CNC system is the development of the CNC system. On the unified operation platform, it can be used for machine tool manufacturers and end users. By changing, adding or cutting structural objects (numerical control functions), serialization can be formed, and the user's special can be conveniently The application and technology are integrated into the control system to quickly realize the open CNC system of different varieties and grades, forming a brand-name product with distinctive personality. At present, the architecture specification, communication specification, configuration specification, operation platform, numerical control system function library and numerical control system function software development tools of the open CNC system are the core of the current research.
Networked CNC equipment is a new highlight of the internationally renowned machine tool fair in the past two years. The network of CNC equipment will greatly meet the demand for information integration in production lines, manufacturing systems, and manufacturing enterprises. It is also the basic unit for implementing new manufacturing models such as agile manufacturing, virtual enterprise, and global manufacturing. Some famous CNC machine tools and CNC system manufacturing companies at home and abroad have launched related new concepts and prototypes in the past two years, such as the "CyberProduction Center" exhibited by Mazak in Japan at EMO2001. Control Center (CPC); Okuma Machine Tool Company exhibited "IT plaza" (Information Technology Plaza, IT Plaza); Open Manufacturing Environment (OME) Etc. reflects the trend of CNC machine tool processing in the direction of networking.
4. Pay attention to the establishment of new technical standards and norms
(1) About CNC system design and development specifications
As mentioned above, open CNC systems have better versatility, flexibility, adaptability, and scalability. The United States, the European Community, and Japan have implemented strategic development plans and implemented open architecture CNC system specifications (OMAC). , OSACA, OSEC) research and development, the world's three largest economies in the short term carried out almost the same scientific plan and norms, indicating a new era of change in CNC technology. In 2000, China began to study and formulate the normative framework of China's ONC numerical control system.
(2) About CNC standards
Numerical control standards are a trend in the development of information technology in manufacturing. The information exchange in the 50 years after the birth of CNC technology is based on the ISO6983 standard, that is, using G, M code to describe how to process, its essential feature is oriented to the processing process, obviously, he has become increasingly unable to meet the high speed of modern CNC technology. The need for development. To this end, a new CNC system standard ISO14649 (STEP-NC) is being researched and developed internationally. Its purpose is to provide a neutral mechanism that does not depend on a specific system and can describe a unified data model throughout the product life cycle. In order to achieve standardization of product information throughout the manufacturing process and even in various industrial fields.
The emergence of STEP-NC may be a revolution in the field of numerical control technology, which will have a profound impact on the development of numerical control technology and the entire manufacturing industry. First of all, STEP-NC proposes a new manufacturing concept. In the traditional manufacturing concept, NC machining programs are concentrated on a single computer. Under the new standard, NC programs can be scattered on the Internet, which is the direction of open and networked CNC technology. Secondly, the STEP-NC CNC system can also greatly reduce the processing drawings (about 75%), machining programming time (about 35%) and processing time (about 50%).
At present, European and American countries attach great importance to the research of STEP-NC, and Europe has initiated the IMS plan of STEP-NC (1999.1.1~2001.12.31). The program is attended by 20 CAD/CAM/CAPP/CNC users, vendors and academic institutions from Europe and Japan. STEP Tools, Inc., a developer of manufacturing data exchange software worldwide, has developed a Super Model for use as a tool for CNC machine tool information exchange with the goal of describing all processes with a uniform specification. This new data exchange format has been validated on prototypes equipped with SIEMENS, FIDIA and the European OSACA-NC control system.
Second, the basic estimate of China's numerical control technology and its industrial development
China's numerical control technology started in 1958. The development process of the past 50 years can be roughly divided into three stages: the first stage from 1958 to 1979, that is, the closed development stage. At this stage, due to the foreign technical blockade and the limitations of China's basic conditions, the development of numerical control technology is relatively slow. The second stage is in the "sixth five-year" and "seven-five" periods of the country and the early stage of the "eighth five-year plan", that is, the introduction of technology, digestion and absorption, and the initial establishment of the localization system. At this stage, due to the reform and opening up and the attention of the state, as well as the improvement of the research and development environment and the international environment, the research and development of CNC technology in China and the localization of products have made great progress. The third stage is the implementation of industrialization research and the stage of market competition during the period of the "Eighth Five-Year Plan" and the "Ninth Five-Year Plan" period. At this stage, the industrialization of China's domestic CNC equipment has made substantial progress. At the end of the "Ninth Five-Year Plan", the domestic market share of domestic CNC machine tools reached 50%, and the domestic CNC system (popular type) also reached 10%.
Throughout the development of China's numerical control technology in the past 50 years, especially after four five-year plans, the following results have been achieved.
(1) It laid the foundation for the development of numerical control technology and basically mastered modern numerical control technology. At present, China has basically mastered the basic technology from numerical control system, servo drive, numerical control host, special plane and its supporting parts. Most of the technologies have already been based on commercial development, and some technologies have been commercialized and industrialized.
(2) Initially formed a numerical control industrial base. On the basis of the results of the research and the commercialization of some technologies, a CNC system production plant with batch production capacity such as Huazhong CNC and Aerospace Numerical Control has been established. Lanzhou Motor Factory, Huazhong CNC and other servo systems and servo motor production plants, as well as Beijing No. 1 Machine Tool Plant and Jinan No. 1 Machine Tool Plant. These production plants have basically formed China's CNC industry base.
(3) Established a basic team of CNC research, development and management talents.
Although we have made great progress in the research and development and industrialization of numerical control technology, we must also clearly understand that the research and development of high-end CNC technology in China, especially the status quo of industrialization and the actual needs of China There is a big gap. Although China's development speed is very fast from a vertical perspective, the horizontal ratio (compared with foreign countries) not only has a gap in technology level, but also has a gap in development speed in some aspects, that is, the gap in the technical level of some high-precision CNC equipment has an increasing trend. From an international point of view, the estimation of China's numerical control technology level and industrialization level is roughly as follows.
(1) At the technical level, it is about 10 to 15 years behind the advanced level of foreign countries, and even more so in high-tech.
(2) At the level of industrialization, the market share is low, the coverage of varieties is small, and scale production has not yet been formed; the professional production level and complete set of functional components are low; the appearance quality is relatively poor; the reliability is not high, and the degree of commercialization is insufficient. The domestic CNC system has not yet established its own brand effect, and the user's confidence is insufficient.
(3) In terms of the ability of sustainable development, the research and development and engineering capabilities of CNC technology before competition are weak; the application of numerical control technology is not strong; the research and formulation of relevant standards are lagging behind.
The main reasons for analyzing the above gaps are as follows.
(1) Aspects of understanding. The understanding of the arduousness, complexity and long-term characteristics of the domestic CNC industry is insufficient; the market is not standardized, the foreign blockade is added, the system is difficult to estimate, and the analysis of the application level and capability of CNC technology in China is insufficient.
(2) System aspects. From the technical point of view, there are many times to pay attention to the problem of numerical control industrialization. From the perspective of system and industrial chain, it is less time to comprehensively consider the issue of numerical control industrialization; there is no complete high-quality supporting system, perfect training and service network support system. .
(3) Mechanism aspects. Bad mechanisms have led to brain drain, which has constrained technological and technological route innovation and product innovation, and has constrained the effective implementation of planning, often planning ideals and implementing difficulties.
(4) Technical aspects. The independent innovation ability of enterprises in technology is not strong, and the engineering ability of core technologies is not strong. The machine tool standard is backward and the level is low. The new standard of numerical control system is not enough research.
3. Strategic thinking on the development of CNC technology and industrialization in China
1. Strategic considerations
China is a big manufacturing country. In the world industrial transfer, we should try to accept the front-end rather than the back-end transfer, that is, we must master the advanced manufacturing core technology. Otherwise, in the new round of international industrial restructuring, China's manufacturing industry will further "empty core." At the cost of resources, environment, and market, we may exchange only the international "processing centers" and "assembly centers" in the new world economic structure, rather than the status of manufacturing centers that master core technologies, which will seriously affect China. The development process of modern manufacturing.
We should attach importance to numerical control technology and industrial issues at the height of the national security strategy. First of all, from the perspective of social security, because manufacturing is the industry with the largest employment population in China, the development of manufacturing industry can not only improve the living standards of the people, but also alleviate China. The pressure of employment guarantees social stability. Secondly, from the perspective of national defense security, Western developed countries have listed high-tech CNC products as national strategic substances, embargo and restrictions on China, "Toshiba Incident" and "Cox Report". "It is the best example."
2. Development strategy
From the perspective of China's basic national conditions, with the strategic needs of the country and the market demand of the national economy as the guide, with the goal of improving the comprehensive competitiveness and industrialization level of China's manufacturing equipment industry, we can dominate the country in the early 21st century with a systematic approach. The key technologies for the development and upgrading of the manufacturing equipment industry and the supporting technologies and supporting technologies that support the industrialization development are the contents of research and development, and realize the leap-forward development of the manufacturing equipment industry.
Emphasis on market demand-oriented, that is, based on CNC terminal products, the CNC industry will be driven by the whole machine (such as CNC lathes, milling machines, high-speed high-precision high-performance CNC machine tools, typical digital machinery, key equipment in key industries, etc.) development of. Focus on solving the reliability and production scale of CNC systems and related functional components (digital servo systems and motors, high-speed electric spindle systems and accessories for new equipment). Without scale, there will be no high-reliability products; without scale, there will be no cheap and competitive products; of course, there is no such thing as a large-scale Chinese CNC equipment.
In the development of sophisticated equipment, it is necessary to emphasize the close integration of production, learning, research and end-users, with the goal of “doing, using, and sellingâ€, and implementing the national will to solve the urgent needs of the country. .
In the aspect of pre-competitive CNC technology, it emphasizes innovation, emphasizes research and development of technologies and products with independent intellectual property rights, and lays a foundation for the sustainable development of China's numerical control industry, equipment manufacturing industry and even the entire manufacturing industry.
This paper introduces the development trend of numerical control technology, makes a basic estimation of China's numerical control technology and its industrial development, and forecasts the development of CNC technology and industrialization in China in terms of strategy and development.