mechanical engineering: an applied discipline that studies and solves all theoretical and practical problems in the development, design, manufacture, installation, operation and repair of various machinery based on relevant natural and technical sciences and combined with technical experience in production practice. Machinery is one of the five elements of production and service in modern society (people, capital, energy, materials and machinery), and participates in the production of energy and materials.
A brief history of the development of mechanical engineering:
Various stone axes, hammers and simple tools made and used by human beings in the Stone Age were the pioneers of later machinery. Thousands of years ago, humans have created mortars and mills for hulling and crushing grains, oranges and windmills for lifting water, cars with wheels, ships sailing in rivers, paddles, paddles and rudders. The power used has developed from manpower to animal power, wind power and water power. The materials used have developed from natural stone, wood, soil and leather to artificial materials. The earliest man-made material was ceramics. The pottery cart for making pottery utensils is a complete machine with three parts: power, transmission and work. Blower has played an important role in the development of human society. The powerful blower makes the metallurgical furnace get high enough temperature to extract metal from ore. During the Western Zhou Dynasty, there was a blower for smelting and casting in China. Before the 15th and 16th centuries, mechanical engineering developed slowly. After the 17th century, the capitalist commodity economy developed rapidly in Britain, France and other countries, and many people devoted themselves to improving the working machines needed by various industries and developing new power machines-steam engines. In the late 18th century, the application of steam engine was extended from mining to textile, flour and metallurgy industries. The main material for making machinery gradually changed from wood to metal. The machinery manufacturing industry began to take shape and gradually became an important industry. Mechanical engineering has developed from a decentralized skill that mainly depends on the individual talents and skills of craftsmen to a theoretical, systematic and independent engineering technology. Mechanical engineering is the main technical factor that contributed to the industrial revolution and the mass production of capitalist machinery in the 18th and 19th centuries.
the development of power machinery in the late 17th century, with the improvement of machinery and the increase of demand for coal and metal ores, it was no longer possible to meet the requirements of improving production only by relying on manpower and animal power, so in the early 18th century, T. newcomen's atmospheric steam engine appeared to drive the mine drainage pump. In 1765, J. Watt invented a steam engine with a separate condenser, which reduced the fuel consumption rate. In 1781, Watt invented a steam engine to provide rotary power, which expanded the application scope of the steam engine. The invention and development of the steam engine promoted the power of mining and industrial production, railways and handling machinery. Almost became the only power source in the 19th century. However, the steam engine and its boiler, condenser and cooling water system are bulky and inconvenient to use. The steam engine was used as the prime Mover in the early stage of power station; At the beginning of the 2th century, steam turbines with high efficiency, high speed and high power appeared, and large and small power turbines adapted to various hydraulic resources also appeared. The internal combustion engine invented in the late 19th century has been improved year by year, and has become a prime Mover with light weight, small size, high efficiency, easy operation and ready start. Internal combustion engines were first used to drive land working machines without power supply, and then used in automobiles, mobile machines (such as tractors, excavators, etc.) and ships, and began to be used in railway locomotives in the middle of the 2th century. The internal combustion engine and the gas turbine and jet engine invented later are also one of the basic technical factors for the successful development of aircraft and spacecraft.
Development of machining technology:
Before the industrial revolution, machinery was mostly made of wood structures by carpenters, and metals (mainly steel and iron) were only used to make instruments, clocks, locks, pumps and small parts on wood-structured machinery. Metal processing mainly depends on the meticulous work of machinists to achieve the required accuracy. With the extensive use of steam engines and the subsequent development of large-scale machinery such as mines, metallurgy, ships and locomotives, more and more metal parts need to be formed and cut, and the metal materials used have developed from copper and iron to steel. Mechanical processing (including casting, forging, welding, heat treatment and other technologies and equipment, as well as cutting technology and machine tools, tools, measuring tools, etc.) has developed rapidly, thus ensuring the supply of various mechanical equipment needed for the development of production. At the same time, with the increase of production batch and the development of precision machining technology, a large number of production methods (interchangeability of parts, professional division of labor and cooperation, assembly line and assembly line, etc.) have been promoted.
Development of basic theory of mechanical engineering:
Before the 18th century, machinists made machinery entirely by personal experience, intuition and craftsmanship, which had little to do with science. It was not until the 18th and 19th centuries that the basic theory of mechanical engineering was gradually formed. Power machinery was first combined with science, such as the theory of T. savery, inventor of steam engine, D. Papan and J. Black, and physicists S. Cano, W.J.M M. Rankin and Kelvin established a new discipline-thermodynamics on the basis of steam engine practice. At the beginning of the 19th century, the study of mechanism such as mechanism structure and motion in machinery was listed as the course of the Institute of Advanced Engineering (Paris Institute of Technology) for the first time. Since the second half of 19th century, fatigue of materials has been considered in design and calculation. Subsequently, fracture mechanics, experimental stress analysis, finite element method, mathematical statistics, computer and so on have been used in design and calculation.
Service field of mechanical engineering:
The service field of mechanical engineering is very wide, and all departments that use machinery, tools and even energy and materials production need mechanical engineering services. Modern mechanical engineering has five service fields:
1. Develop and provide energy conversion machinery, including various power machinery that converts thermal energy, chemical energy, atomic energy, electric energy, fluid pressure energy and natural mechanical energy into mechanical energy suitable for application, and energy conversion machinery that converts mechanical energy into other energy needed;
2. Develop and provide machinery for producing various products, including agricultural, forestry, animal husbandry, fishery machinery and mining machinery, as well as various heavy industrial machinery and light industrial machinery;
3. Develop and provide machinery engaged in various services, such as material handling machinery, transportation machinery, medical machinery, office machinery, ventilation, heating and air conditioning equipment, and environmental protection equipment such as dust removal, purification and noise elimination;
4. Develop and provide machinery for family and personal life, such as washing machines, refrigerators, clocks, cameras, sports equipment and entertainment equipment;
5. Develop and supply all kinds of mechanical weapons.
the subject content of mechanical engineering
The subject content of mechanical engineering can be divided into:
1. Establish and develop the engineering theoretical basis that can be applied to mechanical engineering practically and directly. Such as engineering mechanics, fluid mechanics, engineering materials science, material mechanics, combustion science, heat transfer, thermodynamics, tribology, mechanism science, mechanical principle, mechanical parts, metal technology and nonmetal technology, etc.
2. research, design and develop new mechanical products, improve existing mechanical products and produce a new generation of mechanical products to meet current and future needs;
3. The production of mechanical products, such as the planning and realization of production facilities, the formulation and scheduling of production plans, the formulation and implementation of manufacturing processes, the design and manufacture of process equipment, the determination of labor quota and material quota, and the processing, assembly, packaging and inspection;
4. Operation and management of machinery manufacturing enterprises, such as determining production mode, product sales and production operation management;
5. Application of mechanical products, such as selection, ordering, acceptance, installation, adjustment, operation, maintenance and transformation of mechanical products and complete sets of mechanical equipment used in various industries;
6. Study the problems of environmental pollution and excessive consumption of natural resources caused by the manufacturing and use of mechanical products and the treatment measures.
Branch of mechanical engineering:
Machinery can be divided into power machinery, crushing machinery, transportation machinery and material handling machinery according to their functions;
According to the service industries, it can be divided into agricultural machinery, chemical machinery, mining machinery and textile machinery.
according to the working principle, it can be divided into thermal machinery, turbine machinery, bionic machinery and fluid machinery.
Machines with the same working principle, the same function or serving the same industry have the same problems and characteristics, so there are several different branch disciplines of mechanical engineering. In addition, in the process of research, development, design, manufacture and application, all machinery has to go through several stages with different working properties.
These sub-discipline systems intersect and overlap with each other, so that mechanical engineering may be divided into hundreds of sub-disciplines. For example, power machinery by function has complicated overlapping and overlapping relationship with thermal machinery, fluid machinery, turbine machinery, reciprocating machinery, steam power plant, nuclear power plant, internal combustion engine and gas turbine, and central power station equipment, industrial power plant, railway locomotive, marine engineering and automobile engineering by industry. Marine steam turbines are power machinery, thermal machinery, fluid machinery and turbine machinery, belonging to marine power plants, steam power plants and possibly nuclear power plants. The clockwork and hammer device used to drive the clock are also power machinery, but not thermal machinery, fluid machinery, turbine machinery or reciprocating machinery. Other branches also have similar overlapping and overlapping relationships. But it is of little practical value.
Outlook:
Machinery industry is a basic industry that provides equipment for the national economy, and will change with the development of science and technology.
mechanical engineering aims at increasing production, improving labor productivity and improving production economy to research and develop new mechanical products. In the future era, the research and development of new products will take reducing resource consumption, developing clean renewable energy, and controlling, reducing and even eliminating environmental pollution as super-economic objectives and tasks.
machinery can accomplish the tasks that people can directly accomplish with their hands and eyes, as well as with their feet and ears, and can't, and it can be done faster and better. Modern mechanical engineering has created more and more exquisite and complex machinery and mechanical devices, which have made many fantasies in the past come true.
human beings have been able to swim upstream in the sky and the universe, dive deep into the ocean, peep at tens of billions of light years from afar, and observe cells and molecules closely. The emerging computer hardware and software science has strengthened human beings and partially replaced the scientific and technological means of the human brain, which is artificial intelligence. This new development has shown great influence, and it will continue to create miracles that people can't imagine in the future.
The growth of human intelligence does not reduce the function of hands, on the contrary, it requires hands to do more, more delicate and more complicated work, thus promoting the function of hands. The practice of hands in turn promotes the wisdom of the human brain. In the whole process of human evolution, and in the process of everyone's growth, the brain and hand are mutually promoting and evolving in parallel.
the relationship between artificial intelligence and mechanical engineering is similar to that between brain and hand, and the only difference is that the hardware of artificial intelligence needs to be manufactured by machinery. In the past, all kinds of machinery could not be separated from human operation and control, and their reaction speed and operation accuracy were limited by the slowly evolving human brain and nervous system. Artificial intelligence will eliminate this limitation. The mutual promotion and parallel progress between computer science and mechanical engineering will make mechanical engineering start a new round of great development at a higher level.
In the 19th century, the total knowledge of mechanical engineering was still limited. In European universities, it was generally integrated with civil engineering as a discipline, which was called civil engineering, and it gradually became an independent discipline in the second half of the 19th century. In the 2th century, with the development of mechanical engineering technology and the increase of total knowledge, mechanical engineering began to decompose, and specialized branches appeared one after another. This trend of decomposition reached its peak in the middle of the 2th century, that is, around the end of the Second World War.
As the total knowledge of mechanical engineering has expanded far beyond personal control, it is impossible to view and coordinate the overall situation of a slightly large-scale project, and narrow the scope of technical exchange, which hinders the emergence of new technologies and the overall progress of technology, and its adaptability to changes in external conditions is poor. The experts in the closed specialty have too narrow knowledge, too specialized in considering problems, and it is difficult to cooperate and coordinate in collaborative work, which is also not conducive to continuing self-study and improvement. Therefore, since the middle and late 2th century, there has been a comprehensive trend. People pay more attention to the basic theory, broaden the professional fields, and merge the over-differentiated majors.
The repeated cycle of integration-professional differentiation-re-integration is a reasonable and necessary process of knowledge development. Experts from different disciplines have exquisite professional knowledge and sufficient comprehensive knowledge to know and understand the problems of other disciplines and the overall appearance of the project, so as to form a powerful collective that works together.
integration and specialty are multi-level. There is a contradiction between comprehensiveness and specialty in mechanical engineering; There are also comprehensive and professional problems in comprehensive engineering technology. In all human knowledge, including social science, natural science and engineering technology, there are also comprehensive and professional problems at a higher level and more macro.
mechatronics:
The general term for mechatronics technology and mechatronics products is formed after introducing microelectronic components and technologies into mechatronics products. Mechatronics technology, also known as mechatronics technology, is a systematic technology that integrates mechanical engineering, microelectronics technology, information processing technology and other technologies. Mechatronics product is a multifunctional stand-alone or complete device with software and hardware systems designed and produced by using mechatronics technology, which usually consists of mechanical body, microelectronic device, sensor and actuator. Electromechanical integration technology involves mechanical engineering (such as mechanism, machining and precision technology, etc.), electrician and electronic technology (such as electromagnetism, computer technology and electronic circuit, etc.) and * * * technology (such as system technology, control technology and sensor technology, etc.). Electromechanical integration products mainly include commodity production (such as robots, automatic production lines and factories, etc.), commodity circulation (such as CNC packaging machinery and systems, microcomputer-controlled transportation machines and CNC engineering machinery and equipment, etc.), commodity storage and sales (such as automatic warehouses, automatic weighing and sales and cash processing systems, etc.), social services (such as automated office machinery and medical and environmental protection facilities, etc.) and family, scientific research, agriculture, forestry, animal husbandry and fishery, aerospace and national defense. Mechatronics has greatly changed the technical structure, product structure, function and composition, production mode and management system of machinery industry.
the concept of "Mechatronics technology" was first put forward by Japanese business circles around 197. at that time, they named it "mechatronics", which combined applied mechanical technology with electronic technology. With the rapid development and wide application of computer technology, mechatronics technology has achieved unprecedented development, and it has been generally decomposed into interrelated systems technology, which integrates computer and information technology, automatic control technology, sensor detection technology, servo drive technology and mechanical technology, and is developing in the direction of optomechatronics, and its application scope is increasing.
mechatronics technology specifically includes the following contents:
1. Mechanical technology: Mechanical technology is the foundation of mechatronics, and the focus of mechanical technology lies in how to adapt to mechatronics technology and use other high and new technologies to update concepts and realize structural, material and performance improvement.