Graduation thesis of mechatronics
The type and level of mechanical and electrical products and corresponding production equipment is one of the important symbols of a country's industrial basic ability. Optical, mechanical and electrical integration technology can reduce the volume and weight of products and reduce resource consumption; Or enhance intelligence and reliability, so that products have better cost performance; Or reduce costs and let more people enjoy new products ... The essence of change is to make products more competitive in the market. The progress of mechanical and electrical products production equipment will often lead to the upgrading of technology and products in a specific production industry, which will lead to qualitative changes and even revolutionary leaps in industrial production and people's lives. The purpose of supporting the development of this technical field is to improve and change the performance, quality, variety structure and supporting position of traditional electromechanical products, develop a new generation of intelligent products with international competitiveness, and promote the upgrading of traditional electromechanical products; Develop highly automated and high-precision manufacturing equipment to meet the needs of various departments of the national economy for technical equipment. In 2005, the technological innovation fund for small and medium-sized scientific and technological enterprises will focus on supporting the following six technological products suitable for small and medium-sized enterprises in the field of optical, mechanical and electrical integration: l, industrial production process control system; 2. High-performance intelligent instruments; 3. Advanced manufacturing technology and equipment; 4, medical instrument technology, equipment and medical software; 5. Informatization and automation of power plants and power systems; 6. Technical products related to the ground motor vehicle industry.
(A) Introduction to mechatronics
Mechatronics is the cross-integration of mechanics, microelectronics, control, computer, information processing and other disciplines. Its development and progress depend on the progress and development of related technologies. Its main development direction is digitalization, intelligence, modularization, networking, humanization, miniaturization, integration, integration and greening.
(2) The introduction of numerical control technology of mechatronics representative industry.
1. With the rapid development of computer technology, the traditional manufacturing industry began to undergo fundamental changes. Industrially developed countries have invested heavily in the research and development of modern manufacturing technology and put forward a brand-new manufacturing model. In modern manufacturing system, numerical control technology is the key technology, which integrates microelectronics, computer, information processing, automatic detection, automatic control and other high and new technologies. It has the characteristics of high precision, high efficiency and flexible automation, and plays a decisive role in realizing flexible automation, integration and intelligence in manufacturing industry. At present, the numerical control technology is undergoing fundamental changes, from the dedicated closed-loop control mode to the universal open real-time dynamic full closed-loop control mode. On the basis of integration, the numerical control system has realized ultra-thin and ultra-miniaturization; On the basis of intelligence, it integrates computer, multimedia, fuzzy control, neural network and other multidisciplinary technologies. The numerical control system realizes high-speed, high-precision and high-efficiency control, and can automatically correct, adjust and compensate various parameters in the machining process, thus realizing online diagnosis and intelligent fault handling. On the basis of networking, CAD/CAM is integrated with CNC system, and machine tools are networked to realize centralized control of group control machining.
For a long time, China's numerical control system is a traditional closed architecture, and the numerical control system can only be used as the motion controller of non-intelligent machine tools. The variables of machining process are preset in the form of fixed parameters according to experience, and the machining program is compiled manually or through CAD/CAM and automatic programming system before actual machining. There is no feedback control link between CAD/CAM and CNC, and CNC is only a closed open-loop actuator in the whole manufacturing process. In complex environment and changeable conditions, machining parameters such as tool combination, workpiece material, spindle speed, feed speed, tool path, cutting depth, step length and machining allowance can not be dynamically adjusted in real time according to external interference and random factors in the field environment, and the set values in CAD/CAM can not be randomly corrected through feedback control, thus affecting the working efficiency of CNC machine tools and the machining quality of products. It can be seen that the fixed program control mode and closed architecture of the traditional numerical control system have restricted the development of numerical control to multivariable intelligent control, and have not adapted to the increasingly complex manufacturing process. Therefore, it is imperative to reform the numerical control technology.
Numerical control machining technology is an advanced manufacturing technology, which can greatly improve the accuracy and production efficiency of machined parts. It can not only adapt to single-piece and various batch production, but also process parts with complex shapes and high precision that are difficult to process by traditional methods. Therefore, the development of modern numerical control machining technology and its equipment and related machining technology is the basis for realizing automation, flexibility and integrated production in machinery manufacturing industry, which will promote profound changes in product structure, production mode and management system of machinery manufacturing industry, and better play the important role of digital technology and information technology in improving manufacturing level. The fund will focus on supporting technological innovation projects of CNC units with good market prospects and high-performance CNC manufacturing equipment with structural and technological innovations. (1) highly reliable numerical control system and drive system with market competitiveness; (2) High-performance machining programming software and application software; (3) Advanced CNC machine tools and their key functional components; (4) Advanced CNC machining tools
This paper briefly introduces the development trend of numerical control technology and equipment in the world and the present situation of technical development and industrialization of numerical control equipment in China. On this basis, under the new environment of China's entry into WTO and further opening to the outside world, the importance of developing China's numerical control technology and equipment and improving China's manufacturing informatization level and international competitiveness is discussed, and some views on developing China's numerical control technology and equipment are put forward from two aspects of strategy and tactics.
The technical level and modernization degree of equipment industry determine the level and modernization degree of the whole national economy. Numerical control technology and equipment is the enabling technology and the most basic equipment for developing emerging high-tech industries and cutting-edge industries (such as information technology and its industries, biotechnology and its industries, aviation, aerospace and other national defense industries). Marx once said that "the difference between various economic times lies not in what is produced, but in how it is produced and by what means of labor". Manufacturing technology and equipment are the most basic means of production in human production activities, and numerical control technology is the core technology of advanced manufacturing technology and equipment today. In today's world, numerical control technology is widely used in manufacturing industry, in order to improve the manufacturing capacity and level, and improve the adaptability and competitiveness to the dynamic and changeable market. In addition, the developed countries in the world have also listed CNC technology and equipment as national strategic materials, not only taking significant measures to develop their own CNC technology and industry, but also implementing a blockade and restriction policy on China's "high-precision" CNC key technologies and equipment. In short, vigorously developing 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 their comprehensive national strength and national status.
Numerical control technology is a technology that uses digital information to control the movement and working process of machinery. Numerical control equipment is a mechatronic product formed by the infiltration of new technologies represented by numerical control technology into traditional manufacturing and emerging manufacturing, which is called digital equipment. Its technical scope covers many fields: (1) mechanical 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 development trend of numerical control technology
The application of numerical control technology has not only brought revolutionary changes to the traditional manufacturing industry, making the manufacturing industry a symbol of industrialization, but also played an increasingly important role in the development of some important industries (IT, automobile, light industry, medical care, etc.). ) With the continuous development of numerical control technology and the continuous expansion of application fields, the digitalization of equipment required by these industries has become a major trend of modern development. According to the development trend of numerical control technology and its equipment in the world, its main research hotspots are [1 ~ 4].
1. 1 New trend of high-speed and high-precision machining technology and equipment
Efficiency and quality are the main components of advanced manufacturing technology. High-speed and high-precision machining technology can greatly improve efficiency, improve product quality and grade, shorten production cycle and improve market competitiveness. Therefore, Japan Advanced Technology Research Association listed it as one of the five major technologies of modern manufacturing, and CIRP identified it as one of the central research directions in 2 1 century.
In the field of automobile industry, the production cycle of 300,000 cars per year is 40 seconds, and multi-variety processing is one of the key problems that automobile equipment must solve. In the aerospace field, most of the machined parts are thin-walled ribs with poor stiffness, and the materials are aluminum or aluminum alloy. Only under the condition of high cutting speed and small cutting force can these ribs and walls be machined. Recently, large-scale components such as wings and fuselage are manufactured by hollowing out large-scale integral aluminum alloy blanks, instead of assembling multiple parts through numerous rivets and screws, so that the strength, stiffness and reliability of the components are improved. All these require high speed, high precision and high flexibility for processing equipment.
According to EMO200 1, the feed speed of high-speed machining center can reach 80m/min or even higher, and the idling speed can reach about 100m/min. At present, many automobile factories in the world, including Shanghai General Motors Corporation in China, have partially replaced modular machine tools with production lines composed of high-speed machining centers. The HyperMach machine tool of Cincinnati, USA has a maximum feed speed of 60m/min, a fast speed of 100m/min, an acceleration of 2g and a spindle speed of 60000r/min. It only takes 30 minutes to process a thin-walled aircraft part, while it takes 3 hours to process the same part on a common high-speed milling machine and 8 hours on a common milling machine. The spindle speed and acceleration of the double-spindle lathe produced by German DMG company reach 12* respectively! 000 rpm and 1 g.
In terms of machining accuracy, in recent 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 ~ 5μ m to 1 ~ 1.5μ m, and the ultra-precision machining accuracy has begun to enter the nanometer level (0.0 1μm).
In terms of reliability, the MTBF value of foreign numerical control devices is above 6000h, and the MTBF value of servo system is above 30000h, which shows very high reliability.
In order to realize high-speed and high-precision machining, motorized spindle, linear motor and other supporting functional components have developed rapidly and their application fields have been further expanded.
1.25 axis linkage machining and compound machining machine tools developed rapidly.
Using five-axis linkage to process three-dimensional curved parts, the tool can cut the best geometric shape, which not only has high smoothness, but also greatly improves efficiency. Generally speaking, the efficiency of 1 five-axis machine tool can be equivalent to that of two three-axis machine tools, especially when cubic boron nitride, a superhard material milling cutter, is used for high-speed milling hardened steel parts, five-axis machining can bring more benefits than three-axis machining. However, in the past, due to the complex structure of five-axis CNC system and host computer, the programming technology was difficult, and its price was several times higher than that of three-axis CNC machine tools, which restricted the development of five-axis CNC machine tools.
At present, due to the appearance of motorized spindle, the structure of compound spindle head used for 5-axis linkage machining is greatly simplified, its manufacturing difficulty and cost are greatly reduced, and the price gap of CNC system is narrowed. Thus, the development of compound spindle head five-axis linkage machine tool and compound machining machine tool (including five-sided machining machine tool) is promoted.
At EMO200 1 exhibition, NIKO's 5-face machining machine tool adopted the compound spindle head, which can realize the machining of 4 vertical faces and arbitrary angles, so that 5-face machining and 5-axis machining can be realized on the same machine tool, and the machining of inclined planes and inverted cone holes can also be realized. DMUVoution series machining centers exhibited by German DMG company can carry out five-sided machining and five-axis linkage machining under one clamping, and can be directly or indirectly controlled 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 in 2 1 century will be an intelligent system, which includes all aspects of the numerical control system: in order to pursue the intelligence of machining efficiency and machining quality, such as adaptive control of machining process and automatic generation of process parameters; In order to improve the driving performance and intelligent connection, such as feedforward control, adaptive operation of motor parameters, automatic load identification, automatic selection and self-correction. Simplify programming and simplify the intelligence of operation, such as intelligent automatic programming and intelligent man-machine interface; There are also intelligent diagnosis, intelligent monitoring, convenient system diagnosis and maintenance.
In order to solve the problems existing in closed traditional numerical control system and industrial production numerical control application software. At present, many countries are studying open CNC systems, such as NGC (Next Generation Workstation/Machine Tool Control) in the United States, OSACA (Open System Structure without Action Control System) in Europe, OSEC (Open System Environment of Controller) in Japan, ONC (Open Digital Control System) in China, etc. The openness of CNC system has become the future of CNC system. The so-called open CNC system means that the development of CNC system can be oriented to machine tool manufacturers and end users on a unified operating platform. By changing, adding or reducing structural objects (CNC functions), serialization can be formed, and users' special applications and technical know-how can be easily integrated into the control system, so as to quickly realize open CNC systems of different varieties and grades and form brand-name products with distinctive personality. At present, the architecture specification, communication specification, configuration specification, running platform, CNC system function library and CNC system function software development tools of open CNC system are the core of current research.
Networked numerical control equipment is a new bright spot in the internationally renowned machine tool Expo in recent two years. The networking of CNC equipment will greatly meet the information integration needs of production lines, manufacturing systems and manufacturing enterprises, and it is also the basic unit to realize new manufacturing modes such as agile manufacturing, virtual enterprise and global manufacturing. Some well-known CNC machine tools and CNC system manufacturing companies at home and abroad have introduced related new concepts and prototypes in recent two years, such as "CyberProductionCenter" (CPC)； for short) exhibited by Mazak Yamazaki at EMO200 1; Japan's Daisuke Machine Tool Company exhibited "ITplaza" (Information Technology Plaza, referred to as IT Plaza); The Open Manufacturing Environment (OME) exhibited by Siemens in Germany reflects the trend of NC machine tool processing towards networking.
1.4 Pay attention to the establishment of new technical standards and specifications.
1.4. 1 code for design and development of numerical control system
As mentioned above, the open CNC system has better universality, flexibility, adaptability and expansibility. The United States, Europe and Japan have successively implemented strategic development plans and studied and formulated open architecture CNC system specifications (OMAC, OSACA and OSEC). The three largest economies in the world have made almost the same scientific plans and specifications in a short time, which indicates the arrival of a new period of change in numerical control technology. In 2000, China also began to study and formulate the standard framework of ONC CNC system in China.
. 4.2 About CNC standards
Numerical control standard is the development trend of manufacturing informatization. In the 50 years after the birth of numerical control technology, information exchange is based on ISO6983 standard, that is, G code and M code are used to describe how to process, and its essential feature is process-oriented. Obviously, it can no longer meet the needs of the rapid development of modern numerical control technology. Therefore, a new numerical control system standard ISO 14649 (Step-NC) is being studied and formulated internationally, aiming at providing a neutral mechanism that can describe the unified data model of the whole product life cycle without depending on a specific system, thus realizing the standardization of product information in the whole manufacturing process and even in various industrial fields.
The appearance of STEP-NC may be a revolution in the field of numerical control technology, which will have a far-reaching impact on the development of numerical control technology and even the whole manufacturing industry. First of all, STEP-NC put forward a brand-new manufacturing concept. In the traditional manufacturing concept, NC machining programs are concentrated on a single computer. Under the new standard, numerical control programs can be published on the Internet, which is the direction of open and networked development of numerical control technology. Secondly, STEP-NC system can greatly reduce the processing drawings (about 75%), 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 IMS plan of STEP-NC (1999.1.1~ 2001.12.31). Twenty CAD/CAM/CAPP/CNC users, manufacturers and academic institutions from Europe and Japan participated in this project. STEPTools is an American company and a global developer of data exchange software. He developed a super model for information exchange of CNC machine tools, with the goal of describing all machining processes with unified specifications. At present, this new data exchange format has been verified on the prototype equipped with Siemens, FIDIA and European OSACA-NC numerical control systems.
2. Basic estimation of numerical control technology and its industrial development in China.
China's numerical control technology started from 1958, and the development course of nearly 50 years can be roughly divided into three stages: the first stage is from 1958 to 1979, that is, the closed development stage. At present, the development of numerical control technology is relatively slow due to the technical blockade of foreign countries and the limitation of basic conditions in China. The second stage is in the Sixth Five-Year Plan, the Seventh Five-Year Plan and the early Eighth Five-Year Plan, that is, the stage of introducing technology, digesting and absorbing, and initially establishing a localization system. At this stage, due to the reform and opening up and the attention of the state, as well as the improvement of R&D environment and international environment, China's numerical control technology research and development and product localization have made great progress. The third stage is the late Eighth Five-Year Plan and the Ninth Five-Year Plan, that is, industrialization research and market competition. At present, the industrialization of domestic CNC equipment in China 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%.
Looking at the development of numerical control technology in China in the past 50 years, especially after four five-year plans, the following achievements have been made in general.
A 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 of CNC system, servo drive, CNC mainframe, special plane and its accessories, most of which have the foundation of commercial development, and some technologies have been commercialized and industrialized.
B. the numerical control industrial base was initially formed. On the basis of tackling key problems and commercialization of some technologies, CNC system manufacturers with mass production capacity such as Huazhong CNC and Aerospace CNC have been established. Servo system and servo motor manufacturers such as Lanzhou Motor Factory and Huazhong CNC, as well as CNC host manufacturers such as Beijing No.1 Machine Tool Factory and Jinan No.1 Machine Tool Factory. These factories have basically formed the numerical control industrial base in China.
Established a basic team of CNC research, development and management personnel.
Although great progress has been made in the R&D and industrialization of numerical control technology, we should also clearly realize that the R&D of high-end numerical control technology in China, especially the technical level of industrialization, is still far from the actual demand in China. Although the development speed of China is very fast in the vertical direction, the horizontal ratio (compared with foreign countries) has a gap not only in the technical level, but also in the development speed in some aspects, that is, the gap in the technical level of some high-tech CNC equipment tends to expand. The international estimate of China's numerical control technology level and industrialization level is roughly as follows.
A from the technical level, it is about 10 ~ 15 years behind the advanced foreign level, and it is even bigger from the high-tech point of view.
B industrialization level, low market share and small variety coverage, which has not yet formed large-scale production; The specialized production level and complete set capacity of functional parts are low; The appearance quality is poor; The reliability is not high and the degree of commercialization is insufficient; Domestic CNC system has not yet established its own brand effect, and the user's confidence is insufficient.
C. In terms of sustainable development ability, the research, development and engineering ability of NC technology before competition is weak; The application field of numerical control technology has not been greatly expanded; The research and formulation of relevant standards and norms is relatively lagging behind.
The main reasons for the above gap are as follows.
A. cognition. Insufficient understanding of the arduousness, complexity and long-term nature of the domestic CNC industry process; Insufficient estimation of market irregularities, foreign blockade and strangulation, and institutional difficulties; Insufficient analysis of the application level and ability of numerical control technology in China.
B. System aspect. Pay more attention to the problem of NC industrialization from the technical point of view, and pay less attention to the problem of NC industrialization from the perspective of system and industrial chain; There is no complete high-quality supporting system, perfect training and service network and other supporting systems
C. mechanism. Poor mechanism leads to brain drain, which restricts the innovation of technology, technical route and products and the effective implementation of planning, which is often ideal and difficult to implement.
D. technical aspects. The independent innovation ability of enterprises in technology is not strong, and the engineering ability of core technologies is not strong. The standard of machine tools is backward and low, and the research on the new standard of CNC system is not enough.
3 China numerical control technology and strategic thinking of industrialization development.
3. 1 Strategic considerations
China is a big manufacturing country, so we should try our best to accept the front-end transfer rather than the back-end transfer in the world industrial transfer, that is, master the advanced manufacturing core technology, otherwise our manufacturing industry will be further hollowed out in the new round of international industrial restructuring. At the cost of resources, environment and market, we may only get the international "processing center" and "assembly center" in the new economic structure of the world, rather than the manufacturing center position with core technologies, which will seriously affect the development process of China's modern manufacturing industry.
We should pay attention to numerical control technology and industrial problems from the perspective of national security strategy. First of all, from the perspective of social security, as the manufacturing industry has the largest employment population in China, developing the manufacturing industry can not only improve people's living standards, but also ease the employment pressure in China and ensure social stability. Secondly, from the perspective of national defense security, western developed countries list high-tech CNC products as national strategic materials and impose embargoes and restrictions on China. Toshiba Incident and Cox Report are the best examples.
3.2 Development strategy
Starting from China's basic national conditions, guided by the national strategic demand and the national economic market demand, and aiming at improving the comprehensive competitiveness and industrialization level of China's manufacturing equipment industry, the key technologies that can lead the development and upgrading of China's manufacturing equipment industry at the beginning of 2 1 century, as well as supporting technologies and supporting technologies that support the industrialization development, are selected as research and development contents to realize the leap-forward development of China's manufacturing equipment industry.
Emphasis on market demand-oriented, that is, focusing on CNC end products, the whole machine (such as CNC lathes, milling machines, high-speed and high-precision CNC machine tools, typical digital machinery, key equipment in key industries, etc.). ) has promoted the development of the numerical control industry. Focus on solving the reliability and production scale of CNC system and related functional components (digital servo system and motor, high-speed motorized spindle system and new equipment accessories, etc.). ). Without scale, there would be no products with high reliability; Without scale, there will be no competitive products at low prices; Of course, it is hard to have a bright future without the numerical control equipment of China scale.
In the research and development of high-tech equipment, we should emphasize the close combination of production, learning, research and end users, take "making, using and selling" as the goal, and carry out key research according to the will of the country to solve the urgent needs of the country.
In the aspect of pre-competition CNC technology, it emphasizes innovation and research and development of technologies and products with independent intellectual property rights, which lays the foundation for the sustainable development of CNC industry, equipment manufacturing industry and even the whole manufacturing industry in China.
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