Improve the importance of my country's manufacturing informatization level and international competitiveness, and put forward several views on the development of my country's CNC technology and equipment from two levels of strategy and strategy.
The technological level and modernization degree of the equipment industry determine the level and modernization degree of the entire national economy. Numerical control technology and equipment are the development of emerging high-tech industries and cutting-edge industries (such as information technology and its industries, biotechnology and its industries, aviation, aerospace, etc.) National defense industry) enabling technology and the most basic equipment.
Marx once said that "the difference between various economic times lies not in what is produced, but in how to produce and what means of labor are used to produce." Manufacturing technology and equipment are the most basic means of production for human production activities, and numerical control technology is the core technology of today's advanced manufacturing technology and equipment.
Nowadays, the manufacturing industries of all countries in the world widely adopt CNC technology to improve the manufacturing capacity and level, and improve the adaptability and competitiveness of the dynamic and changeable market. In addition, the developed countries in the world have also listed numerical control technology and numerical control equipment as national strategic materials. They have not only taken major measures to develop their own numerical control technology and its industry, but also provided great support to my country in terms of "high-precision" key numerical control technology and equipment. Implement blockade and restriction policies. In short, the vigorous development of advanced manufacturing technology with numerical control technology as the core has become an important way for developed countries in the world to accelerate economic development and improve overall national strength and national status.
Numerical control technology is a technology that uses digital information to control mechanical movements and working processes. Numerical control equipment is a mechatronic product formed by the penetration of new technologies represented by numerical control technology into traditional manufacturing industries and emerging manufacturing industries, the so-called digital equipment Its technical scope covers many fields:
- (1) machinery manufacturing technology;
- (2) information processing, processing and transmission technology;
- (3) automatic control technology;
- (4) servo drive technology;
- (5) sensor technology;
- (6) software Technology etc.
1 The development trend of CNC technology
The application of CNC technology has not only brought revolutionary changes to the traditional manufacturing industry, and made the manufacturing industry a symbol of industrialization, but with the continuous development of CNC technology and the expansion of application fields, it has contributed to some important industries (IT, automotive , Light industry, medical, etc.) are playing an increasingly important role, because the digitalization of equipment required by these industries has become a major trend in modern development. Judging from the current development trend of numerical control technology and equipment in the world, its main research hotspots are as follows [1~4].
1.1 New trends in high-speed, high-precision machining technology and equipment
Efficiency and quality are the mainstay of advanced manufacturing technology. High-speed, high-precision processing technology can greatly improve efficiency, improve product quality and grade, shorten production cycle and improve market competitiveness. For this reason, the Japanese Advanced Technology Research Institute will list it as one of the five major modern manufacturing technologies, and the International Society of Production Engineering (CIRP) has identified it as one of the central research directions in the 21st century.
In the car industry, the production cycle for an annual output of 300,000 cars is 40 seconds per car, and multi-variety processing is one of the key problems that must be solved for car equipment; in the aviation and aerospace industries, most of the parts processed are thin-walled And thin ribs have poor rigidity, and the material is aluminum or aluminum alloy. These ribs and walls can be processed only when the cutting speed is high and the cutting force is small. Recently, large-scale aluminum alloy blanks have been "emptied" to manufacture large parts such as wings and fuselages to replace multiple parts. They are assembled through numerous rivets, screws and other coupling methods, so that the strength, rigidity and reliability of the components can be obtained. improve. All these put forward high-speed, high-precision and high-flexibility requirements for processing equipment.
From the EMO2001 exhibition, the feed speed of the high-speed machining center can reach 80m/min or even higher, and the dry running speed can reach about 100m/min. At present, many automobile factories in the world, including my country's Shanghai General Motors Corporation, have adopted high-speed machining centers to partially replace modular machine tools. The HyperMach machine tool of American CINCINNATI has a maximum feed rate of 60m/min, a rapid rate of 100m/min, an acceleration of 2g, and a spindle speed of 60 000r/min. It only takes 30 minutes to process a thin-walled aircraft part, while the same part needs 3h to process on a general high-speed milling machine, and 8h on a general milling machine; the spindle speed and acceleration of the double-spindle lathe from DMG in Germany are 12*!000r/mm And 1g.
In terms of machining accuracy, in the past 10 years, the machining accuracy of ordinary CNC machine tools has increased from 10μm to 5μm, and the precision machining center has increased from 3～5μm to 1～1.5μm, and the ultra-precision machining accuracy has begun to enter the nanometer level. (0.01μm).
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 30000h, showing very high reliability.
In order to realize high-speed and high-precision machining, the supporting functional components such as electric spindle and linear motor have been developed rapidly, and the application field has been further expanded.
1.2 Rapid development of 5-axis simultaneous machining and compound machining machine tools
The use of 5-axis linkage to process three-dimensional curved parts can be cut with the best geometry of the tool, which not only has high finish, but also greatly improves efficiency. It is generally believed that the efficiency of one 5-axis linkage machine tool can be equal to that of two 3-axis linkage machine tools, especially when using cubic boron nitride and other superhard material milling cutters for high-speed milling of hardened steel parts, 5-axis linkage machining is comparable to 3-axis linkage Processing to play a higher efficiency. However, in the past, due to the complex structure of the 5-axis CNC system and the host computer, its price was several times higher than that of the 3-axis CNC machine tool. In addition, the programming technology was more difficult, which restricted the development of the 5-axis CNC machine tool.
At present, due to the emergence of electric spindles, the structure of the composite spindle head that realizes 5-axis simultaneous machining is greatly simplified, its manufacturing difficulty and cost are greatly reduced, and the price gap of CNC systems is narrowed. Therefore, the development of compound spindle head type 5-axis linkage machine tools and compound processing machine tools (including 5-sided processing machine tools) has been promoted.
At the EMO2001 exhibition, Nippon Koki's 5-sided machining machine adopts a composite spindle head, which can realize the machining of 4 vertical planes and machining at any angle, so that 5-face machining and 5-axis machining can be realized on the same machine tool. It can realize the processing of inclined surface and inverted taper hole. The German DMG company exhibited the DMUVoution series of machining centers, which can process 5-sides and 5-axis linkage processing in one clamping, and can be controlled directly or indirectly by CNC system or CAD/CAM.
1.3 Intelligence, openness, and networking have become the main trends in the development of contemporary CNC systems
The numerical control equipment of the 21st century will be a system with a certain degree of intelligence, and the content of intelligence includes all aspects of the numerical control system: in order to pursue the intelligence of processing efficiency and processing quality, such as adaptive control of the processing process, automatic process parameters Generation; In order to improve the drive performance and use the convenience of intelligence, such as feedforward control, adaptive calculation of motor parameters, automatic load recognition, automatic selection model, self-tuning, etc.; simplify programming and simplify the operation of intelligence, such as intelligence Intelligent automatic programming, intelligent man-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 closedness of CNC system and the industrial production of CNC application software. Many countries are currently conducting research on open CNC systems, such as NGC (The Next Generation Work-Station/Machine Control) in the United States, OSACA (Open System Architecture for Control within Automation Systems) in the European Community, OSEC (Open System Environment in Japan) for Controller), China's ONC (Open Numerical Control System), etc. Open CNC system has become the future road of CNC system. The so-called open numerical control system means that the development of numerical control system can be on a unified operating platform, facing machine tool manufacturers and end users, by changing, adding, or tailoring structural objects (numerical control functions) to form serialization, and it is convenient for users to specialize The application and technical know-how are integrated into the control system to quickly realize different varieties and different grades of open CNC systems, forming brand-name products with distinctive personality. At present, the architecture specification, communication specification, configuration specification, operating platform, numerical control system function library and numerical control system function software development tools of the open CNC system are the core of current research.
Networked CNC equipment is a new highlight of the famous international machine tool expo in the past two years. The networking of CNC equipment will greatly meet the information integration needs of production lines, manufacturing systems, and manufacturing companies, and it is also a basic unit for realizing new manufacturing models such as agile manufacturing, virtual enterprises, and global manufacturing. Some well-known CNC machine tools and CNC system manufacturing companies at home and abroad have launched related new concepts and prototypes in the past two years. For example, in the EMO2001 exhibition, the "CyberProduction Center" (intelligent production) exhibited by Mazak (Mazak) of Japan Control Center (CPC for short); "IT plaza" (IT Plaza) exhibited by Okuma Machine Tool Company of Japan; Open Manufacturing Environment (OME) exhibited by Siemens (Siemens) in Germany Etc., reflecting the development trend of CNC machine tool processing towards network.
1.4 Pay attention to the establishment of new technical standards and norms
1.4.1 About CNC system design and development specifications
As mentioned earlier, open CNC systems have better versatility, flexibility, adaptability, and scalability. Countries such as the United States, the European Community, and Japan have implemented strategic development plans and carried out open architecture CNC system specifications (OMAC , OSACA, OSEC) research and formulation, the world's three largest economies have carried out almost the same scientific plans and formulation of norms in a short period of time, heralding the coming of a new period of change in CNC technology. In 2000, my country also began to study and formulate the normative framework of China's ONC CNC system.
1.4.2 About CNC standards
Numerical control standards are a trend in the development of manufacturing informatization. The information exchange in the 50 years after the birth of CNC technology is based on the ISO6983 standard, that is, G and M codes are used to describe how to process. Its essential feature is oriented to the processing process. Obviously, it has become increasingly unable to meet the high speed of modern CNC technology. The need for development. For this reason, a new CNC system standard ISO14649 (STEP-NC) is being studied and formulated internationally. Its purpose is to provide a neutral mechanism that does not depend on specific systems and can describe a unified data model throughout the product life cycle. , So as to realize the standardization of the entire manufacturing process and even product information in various industrial fields.
The emergence of STEP-NC may be a revolution in the field of CNC technology, which will have a profound impact on the development of CNC technology and the entire manufacturing industry. First of all, STEP-NC proposes a brand-new manufacturing concept. In the traditional manufacturing concept, NC processing 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 development of CNC technology. Secondly, the STEP-NC numerical control system can also greatly reduce processing drawings (about 75%), processing programming time (about 35%) and processing time (about 50%).
At present, European and American countries attach great importance to the study of STEP-NC, and Europe initiated the STEP-NC IMS plan (1999.1.1 ~ 2001.12.31). Participating in this program are 20 CAD/CAM/CAPP/CNC users, manufacturers and academic institutions from Europe and Japan. STEP Tools in the United States is a global manufacturer of data exchange software for manufacturing. He has developed a Super Model for the exchange of CNC machine tool processing information. Its goal is to describe all processing processes with a unified specification. At present, this new data exchange format has been verified on prototypes equipped with SIEMENS, FIDIA and European OSACA-NC CNC systems.
2 Basic estimation of my country's numerical control technology and its industrial development
My country's numerical control technology started in 1958, and the development course of the past 50 years can be roughly divided into three stages: the first stage is from 1958 to 1979, which is the closed development stage. At this stage, due to foreign technical blockades and my country's basic conditions, the development of CNC technology is relatively slow. The second stage is during the country's "Sixth Five-Year Plan", "Seventh Five-Year Plan" period and the early stage of the "Eighth Five-Year Plan" period, namely the introduction of technology, digestion and absorption, and the initial establishment of a localization system. At this stage, due to the reform and opening up, the country's attention, and the improvement of the research and development environment and the international environment, the research and development of my country's numerical control technology and the localization of products have made considerable progress. The third stage is the late stage of the country’s "Eighth Five-Year Plan" and the "Ninth Five-Year Plan" period, that is, to implement industrialization research and enter the market competition stage. At this stage, the industrialization of my country's domestic CNC equipment has made substantial progress. At the end of the "Ninth Five-Year Plan" period, the domestic market share of domestic CNC machine tools reached 50%, and the domestic CNC system (popular type) also reached 10%.
Looking at the development history of my country's CNC technology in the past 50 years, especially after four 5-year plans, the following results have been achieved overall.
- a. Lay the foundation for the development of numerical control technology, and basically master modern numerical control technology. Our country has basically mastered the basic technology from CNC system, servo drive, CNC host, special machine and its supporting parts. Most of the technology has the basis for commercial development, and some of the technology has been commercialized and industrialized.
- b. Initially formed a CNC industrial base. On the basis of research results and commercialization of some technologies, CNC system production plants with mass production capabilities such as Huazhong CNC and Aerospace CNC have been established. A number of servo system and servo motor manufacturers such as Lanzhou Motor Factory and Huazhong CNC, as well as several CNC host manufacturers such as Beijing No. 1 Machine Tool Factory and Jinan No. 1 Machine Tool Factory. These production plants have basically formed my country's CNC industrial base.
- c. Established a basic team of numerical control research, development and management talents.
Although considerable progress has been made in the research and development and industrialization of numerical control technology, we must also be soberly aware that the research and development of my country’s high-end numerical control technology, especially in terms of industrialization, is still in line with my country’s actual needs. There is a big gap. Although my country's development speed is very fast from a vertical perspective, the horizontal ratio (compared with foreign countries) not only has a gap in technical level, but also a gap in the development speed in some aspects, that is, the gap in the technical level of some high-precision CNC equipment has a tendency to expand. From an international point of view, the estimated level of my country's CNC technology and industrialization is roughly as follows.
- a. In terms of technical level, it is about 10-15 years behind the advanced level of foreign countries, and it is even greater in terms of high-precision technology.
- b. At the level of industrialization, the market share is low, the variety coverage is small, and mass production has not been formed; the specialized production level of functional components and the complete set capacity 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 user confidence is insufficient.
- c. In terms of the ability of sustainable development, the research and development and engineering capabilities of numerical control technology before the competition are weak; the expansion of numerical control technology application fields is not strong; the research and formulation of relevant standards and specifications are lagging behind.
The main reasons for the analysis of the above gap are as follows.
- a. Understanding. Insufficient understanding of the arduous, complex and long-term characteristics of the domestic CNC industry process; insufficient estimation of market irregularities, foreign blockades and strangulation, and system difficulties; insufficient analysis of the application level and capabilities of my country's CNC technology.
- b. System aspect. There are many times to pay attention to the problems of CNC industrialization from a technical point of view, and less time to comprehensively consider the problems of CNC industrialization from a systematic and industrial chain point of view; there is no complete high-quality supporting system, complete training, service network and other supporting systems. .
- c. Mechanism. Bad mechanisms cause brain drain, restrict technology and technological route innovation, product innovation, and restrict the effective implementation of planning. Often, planning is ideal and difficult to implement.
- d. Technical aspects. Enterprises are not capable of independent innovation in technology, and their core technology engineering capabilities are not strong. The machine tool standard is backward, the level is low, and the new standard of CNC system is not studied enough.
3 Strategic thinking on the development of CNC technology and industrialization in my country
3.1 Strategic considerations
my country is a big manufacturing country. In the world's industrial transfer, it is necessary to accept the transfer of front-end rather than back-end as much as possible, that is, to master the core technology of advanced manufacturing, otherwise, in the new round of international industrial restructuring, my country's manufacturing industry will be further "hollow core". At the cost of resources, environment, and market, what we can exchange may only be the international "processing center" and "assembly center" in the world's new economic structure, rather than the status of a manufacturing center that masters core technologies. This will seriously affect my country The development process of modern manufacturing.
We should pay attention to numerical control technology and industrial issues from the perspective of national security strategy. First of all, from the perspective of social security, because manufacturing is the industry with the largest employment population in our country, the development of manufacturing can not only improve people’s living standards, but also ease our country Employment pressure guarantees social stability; secondly, from the perspective of national defense and security, Western developed countries list high-precision CNC products as national strategic materials, and implement embargoes and restrictions on China, the "Toshiba Incident" and the "Cox Report" "Is the best example.
3.2 Development strategy
From the perspective of my country’s basic national conditions, guided by the country’s strategic needs and the market demand of the national economy, with the goal of improving the comprehensive competitiveness and industrialization level of my country’s manufacturing equipment industry, using a systematic approach, choosing to dominate my country in the early 21st century The key technologies for the development and upgrading of the manufacturing equipment industry, as well as the supporting technologies and supporting technologies that support the development of industrialization, are the contents of research and development to realize the leap-forward development of the manufacturing equipment industry.
Emphasis on market demand-oriented, that is, to focus on CNC terminal products, and drive the CNC industry with complete machines (such as large-volume and wide-area CNC lathes, milling machines, high-speed, high-precision and high-performance CNC machine tools, typical digital machinery, and key industry equipment, etc.) development of. Focus on solving the reliability and production scale issues of the CNC system and related functional components (digital servo system and motor, high-speed electric spindle system and new equipment accessories, etc.). Without scale, there will be no high-reliability products; without scale, there will be no low-priced and competitive products; of course, without scale, China's CNC equipment will eventually hardly have a promising future.
In the research and development of high-precision equipment, it is necessary to emphasize the close integration of production, learning, research, and end users, with the goal of “making it possible, usable, and selling” as the goal, and implement research in accordance with the will of the country to solve the country’s urgent needs .
In terms of pre-competitive numerical control technology, emphasis is placed on innovation and research and development of technologies and products with independent intellectual property rights, laying a foundation for the sustainable development of my country’s numerical control industry, equipment manufacturing industry and the entire manufacturing industry.
