mechanical engineering
With the relevant natural and technical sciences as the theoretical basis, combined with technical experience in production practice, research and solve all theoretical and practical problems in the development, design, manufacture, installation, utilization and repair of all kinds of machinery in the application of the discipline. Machinery is one of the five elements of modern society for production and service (people, capital, energy, materials and machinery), and participate in the production of energy and materials.
A Brief History of Development The various stone axes, stone hammers, and simple tools made and used by humans in the Stone Age and made of wood and leather were the forerunners of the machinery that came later. Thousands of years ago, mankind has created a mortar and mill used for grain shelling and crushing, used to carry water pulleys and windlasses, equipped with wheeled vehicles, sailing in the river boat and oars, sculls, rudders and so on. The power used developed from human power to animal power, wind power and water power. The materials used by the natural stone, wood, earth, leather and other development to man-made materials. The earliest man-made material was ceramic. The pottery car for making ceramic vessels was a complete machine with 3 parts: power, transmission and work. Blowers played an important role in the development of human society. Powerful blowers enabled metallurgical furnaces to obtain high enough temperatures to extract metals from ores. During the Western Zhou Dynasty, China already had a blower for metallurgy and casting. 15-16 centuries ago, the development of mechanical engineering was slow. 17 centuries later, the rapid development of the capitalist commodity economy in Britain, France and other countries, many people were committed to improving the working machinery required by various industries and developing a new power machine - steam engine. 18 centuries later, the application of steam engine spread from the mining industry to the mining industry. In the late 18th century, the application of the steam engine was extended from the mining industry to the textile, flour and metallurgical industries. The main material for making machinery was gradually changed from wood to metal. The machinery manufacturing industry began to take shape and gradually became an important industry. Mechanical engineering developed from a decentralized craft that relied heavily on the individual talents and craftsmanship of craftsmen to a theoretically guided, systematic and independent engineering technology. Mechanical engineering is to contribute to the 18th to 19th century industrial revolution and capitalist mechanical mass production of the main technical factors.
The development of power machinery In the late 17th century, with the improvement of machinery, coal and metal ore demand increased, relying only on manpower and animal power can not adapt to the requirements of the increased production, so in the early 18th century appeared T. Newcomen's atmospheric steam engine, used to drive the mine drainage pumps. 1765, J. Watt invented a separate condenser steam engine, reducing the rate of fuel consumption. In 1781, Watt also created a steam engine to provide rotary power, expanding the scope of application of the steam engine. The invention and development of the steam engine facilitated the motorization of mining and industrial production, railroads and handling machinery. It became almost the only source of power in the 19th century. However, the steam engine and its boiler, condenser and cooling water system are large, bulky and inconvenient to apply. at the end of the 19th century, the electric power supply system and electric motors began to develop and popularize. at the beginning of the 20th century, electric motors have replaced the steam engine in industrial production, and have become the basic power to drive all kinds of working machines. At the beginning of the power station, steam engine was used as the prime mover; at the beginning of the 20th century, high efficiency, high speed and high power steam turbine appeared, and large and small power hydraulic turbine adapted to various water resources also appeared. the internal combustion engine invented in the late 19th century was improved year by year, and became a light and small, high efficiency, easy to maneuver and can be started at any time prime mover. The internal combustion engine was initially used to drive land-based machines that did not have an electric power supply, but was later used in automobiles, mobile machines (e.g., tractors, excavators, etc.) and ships, and began to be used in railroad locomotives in the mid-20th century. The internal combustion engine and the later invention of gas turbines and jet engines are still one of the technological factors underlying the successful development of airplanes, spacecraft, and so on.
The development of machining technology Before the Industrial Revolution, most of the machinery is made by carpenters handmade wooden structures, metal (mainly steel and iron) is only used to manufacture instruments, clocks, locks, pumps and small parts on the wooden structure of the machinery. Metal fabrication relied heavily on the craftsmen's precision work to achieve the required accuracy. With the widespread use of steam engines and the consequent emergence of mining, metallurgy, ships and locomotives and other large-scale machinery development, the need for forming and cutting of metal parts more and more, the metal materials used by copper, iron development to steel-based. Mechanical processing (including casting, forging, welding, heat treatment and other technologies and their equipment, as well as cutting technology and machine tools, cutting tools, gauges, etc.) has developed rapidly, thus ensuring the development of the production of a variety of mechanical equipment needed to supply. At the same time, with the increase in production batch size and the development of precision machining technology, but also promotes the formation of a large number of production methods (parts interchangeability production
, professional division of labor and collaboration, streamlined processing lines and streamlined assembly lines, etc.).
The development of basic theories of mechanical engineering Before the 18th century, mechanical craftsmen all rely on personal experience, intuition and craftsmanship to make machinery, almost nothing to do with science. Until the 18th to 19th century is gradually formed around the basic theory of mechanical engineering. Power machinery was first combined with science, such as the inventor of the steam engine T. Savery and Watt applied the theories of physicists D. Papin and J. Black, physicists S. Carnot, W.J.M. Rankin and Kelvin in the practice of the steam engine on the basis of the establishment of a new discipline - thermodynamics, etc. At the beginning of the 19th century, the study of machinery, such as the structure and movement of the mechanism of the mechanism, the mechanism of the mechanism, and so on, the study of mechanical engineering. At the beginning of the 19th century, the study of mechanical structures and movements was included for the first time in the curriculum of the Ecole Supérieure d'Ingénieurs (Ecole des Arts et Métiers in Paris). In the second half of the 19th century, the fatigue of materials was taken into account in design calculations. Subsequently, fracture mechanics, experimental stress analysis, finite element method, mathematical statistics, electronic computers, etc. have been used in design calculations.
Service areas The service areas of mechanical engineering are very wide, where the use of machinery, tools, and even energy and materials production sectors, all need the services of mechanical engineering. Modern mechanical engineering has five major service areas: ① development and provision of energy conversion machinery, including thermal energy, chemical energy, atomic energy, electrical energy, fluid pressure energy and natural mechanical energy into a variety of mechanical energy suitable for the application of power machinery, as well as the conversion of mechanical energy into the need for other energy energy conversion machinery. (ii) The development and provision of machinery for the production of various products, including machinery for agriculture, forestry, animal husbandry, fisheries and mining machinery, as well as a variety of heavy industry machinery and light industry machinery. (iii) Develop and provide machinery for various services, such as material handling machinery, transportation machinery, medical machinery, office machinery, ventilation, heating and air-conditioning equipment, and dust removal, purification, noise reduction and other environmental protection equipment. (4) To develop and provide machinery for family and personal life, such as washing machines, refrigerators, clocks and watches, cameras, sports equipment and recreational equipment. ⑤ Develop and provide various mechanical weapons.
Subject content The subject content of mechanical engineering can be divided into the following aspects according to the nature of the work: ① Establish and develop the engineering theory foundation that can be practically and directly applied to mechanical engineering. Such as engineering mechanics, fluid mechanics, engineering materials science, mechanics of materials, combustion science, heat transfer, thermodynamics, tribology, mechanism, mechanical principles, mechanical parts, metal technology and non-metallic technology. ② Research, design and development of new mechanical products, improvement of existing mechanical products and production of new generation mechanical products to meet current and future needs. ③ Production of mechanical products, such as planning and realization of production facilities, development of production plans and production scheduling, preparation and implementation of manufacturing processes, design and manufacture of process equipment, determination of labor quotas and material quotas, and processing, assembly, packaging and inspection. ④ Operation and management of machinery manufacturing enterprises, such as determining production methods, product sales, and production operation management. ⑤ Application of mechanical products, such as selecting, ordering, accepting, installing, adjusting, operating, repairing and remodeling mechanical products and complete sets of mechanical equipment used in various industries. ⑥ Study of environmental pollution and excessive depletion of natural resources generated during the manufacturing and use of mechanical products and measures to deal with them.
Subject branches Machinery can be divided into power machinery, crushing machinery, transportation machinery and material handling machinery, etc. according to the function; according to the service industry can be divided into agricultural machinery, chemical machinery, mining machinery and textile machinery, etc.; according to the principle of work can be divided into thermal machinery, turbine machinery, biomimetic machinery and fluid machinery, etc.. The same working principle, the same function or service in the same industry machinery has the same problem and characteristics, so mechanical engineering has several different sub-discipline system. In addition, all the machinery in the research, development, design, manufacture, use of the process, to go through a number of different stages of the nature of the work, according to this, mechanical engineering can be divided into a number of branches of the system that are interlinked and cooperate with each other, such as mechanical research, mechanical design, mechanical manufacturing, mechanical use and maintenance. These sub-discipline systems cross each other, overlap each other, so that mechanical engineering may be divided into hundreds of sub-disciplines. For example, according to the function of power machinery, and according to the working principle of thermal machinery, fluid machinery, turbomachinery, reciprocating machinery, steam power plant, nuclear power plant, internal combustion engine, gas turbine, as well as according to the industry centers power plant equipment, industrial power plant, railroad locomotives, marine turbine engineering, automotive engineering, etc. There are complex intersection and overlap relationship. Marine turbines are power machines, as well as thermal, fluid and turbomachinery, and belong to ship power units, steam power units, and possibly nuclear power units. And the clockwork and weighting devices used to drive clocks are also power machines, but not thermodynamic, fluid, turbomachinery or reciprocating machines. There are similar overlapping and intersecting relationships between other branches. Analyzing this complex relationship and studying the most reasonable branch system of mechanical engineering has some intellectual significance, but little practical value.
Prospects The machinery industry is the basic industry to provide equipment for the national economy, will produce changes with the development of science and technology.
Mechatronics Mechatronics technology and mechatronics products are collectively known as the formation of microelectronic components and technology after the introduction of electromechanical products. Mechatronics technology, also known as mechanical microelectronics technology, is mechanical engineering, microelectronics technology, information processing technology and other technologies into a system technology. Mechatronics products are a kind of multi-functional single machine or complete set of devices with software and hardware systems designed and produced by using mechatronics technology, usually consisting of mechanical body, microelectronic devices, sensors and actuators. Mechatronics technology involves the disciplines of mechanical engineering (such as mechanics, machining and precision technology, etc.), electrical and electronic technology (such as electromagnetism, computer technology and electronic circuits, etc.), *** technology (such as system technology, control technology and sensor technology, etc.). Mechatronics products are mainly used for commodity production (e.g. robots, automatic production lines and factories, etc.), commodity distribution (e.g. CNC packaging machinery and systems, microcomputer-controlled transportation machinery and CNC engineering machinery and equipment, etc.), commodity storage and sales (e.g. automatic warehouses, automatic weighing and sales and cash-handling systems, etc.), social services (e.g. automated office machinery and automated facilities for medical care and environmental protection, etc.) and family, scientific research, agriculture, forestry, fisheries, aerospace and defense and other mechatronic products. Mechatronics make the machinery industry's technological structure, product structure, function and composition, production mode and management system has changed dramatically.
Mechanical engineering and human living environment The development of engineering technology in improving human material civilization and living standards at the same time, but also on the natural environment to play a destructive role. since the middle of the twentieth century, the most prominent problem is the massive consumption of resources, especially energy and pollution of the environment. In the future, the development of new machinery products will be to reduce resource consumption, the development of pure renewable energy, governance, reduce or even eliminate environmental pollution as an important task.
Mechanical engineering specialization and integration In the second half of the 19th century, mechanical engineering became an independent discipline. Into the 20th century, with the development of mechanical engineering technology and the growth of the total amount of knowledge, mechanical engineering began to decompose, one after another, the emergence of specialized sub-disciplines. The trend of decomposition reached its peak in the middle of the 20th century (around the end of the Second World War). As the total amount of knowledge of mechanical engineering has been expanded to far more than a person can grasp, a certain degree of specialization is essential. However, excessive specialization resulted in excessive division of knowledge, narrow vision, unable to collectively view and coordinate the whole picture and overall situation of a slightly large-scale project, and narrow the scope of technical exchanges, hindering the emergence of new technologies and technological progress as a whole, and the ability to adapt to changes in external conditions (such as the emergence of new technologies, new materials and new products, the supply of materials and semi-finished products, and price changes, etc.) is very poor. Experts in closed specialties have too narrow a grasp of knowledge and are too specialized in their considerations, which makes it difficult for them to cooperate and coordinate when working together, and is not conducive to continued self-education and improvement. Therefore, from the middle and late 20th century, mechanical engineering and the trend of synthesis. People pay more attention to basic theories, broaden the field of specialization, merging the specialties that are too finely divided.