Machinery

A brief history of mechanical development

The development of machinery can be divided into two parts in the 20th century.The following is a brief history of the development of machinery.

A brief history of mechanical development, before the 20th century

The symbol of human beings becoming “modern people” is manufacturing tools. The various stone axes, stone hammers and simple and rough wooden and leather tools of the Stone Age were the pioneers of machinery that appeared later.

The evolution from manufacturing simple tools to manufacturing modern machinery composed of multiple parts and components has gone through a long process.

Thousands of years ago, humans have created mortars and mills for hulling and crushing grains, tangerines and wheels for lifting water, carts with wheels, boats and oars, sculls, and rudders that sail in rivers. The power used has evolved from the human’s own physical strength to the use of animal power, water power and wind power. The materials used have evolved from natural stone, wood, soil, and leather to man-made materials.

The earliest man-made material was ceramics. The pottery cart used to make ceramic ware was already a complete machine with three parts: power, transmission and work.

From the Stone Age to the Bronze Age, and then to the Iron Age, the development of blowers used to blow fires played an important role. With a sufficiently powerful blower, the metallurgical furnace can obtain a high enough furnace temperature to smelt metal from the ore.

Rekhmir (about 1450 BC), the 18th dynasty of ancient Egypt, already had a pot-shaped blower for smelting and casting. In China, from 1000 BC to 900 BC, there were blowers for smelting and foundry, and gradually developed from human blasting to animal power and hydraulic blasting.

Before the 15th to 16th centuries, the development of mechanical engineering was slow. However, in the practice of thousands of years, considerable experience and technical knowledge have been accumulated in mechanical development, which has become an important potential for the development of mechanical engineering. After the 17th century, capitalism emerged in Britain, France, and Western European countries, and commodity production began to become the central issue of society.

In the late 18th century, the application of steam engines was extended from mining to textile, flour, metallurgy and other industries. The main material for making machinery has gradually changed from wood to metal that is tougher but difficult to process by hand. The machinery manufacturing industry began to take shape and became an important industry in decades.

Through continuous expansion of practice, mechanical engineering has gradually developed from a decentralized technique that mainly relies on the individual talents and craftsmanship of the craftsmen to become a theoretically guided, systematic and independent engineering technique. Mechanical engineering was the main technical factor that contributed to the industrial revolution in the 18th and 19th centuries and the mass production of capitalist machinery.

Motivation is an important factor in the development of production. In the late 17th century, with the improvement and development of various machinery, as the demand for coal and metal ore increased year by year, people felt that relying on manpower and animal power could not raise production to a new stage.

In the UK, industries such as textiles and milling are increasingly setting up factories by rivers and using water wheels to drive working machinery. However, the underground water in coal mines, tin mines, copper mines and other mines at that time could only be lifted and drained with a lot of animal power.

Under such production needs, Newcomen’s atmospheric steam engine appeared in the early 18th century to drive mine drainage pumps. However, this kind of steam engine has a high fuel consumption rate and is basically only used in coal mines.

In 1765, Watt invented a steam engine with a separate condenser to reduce fuel consumption.

In 1781, Watt created a steam engine to provide rotary power, which expanded the application range of the steam engine. The invention and development of the steam engine enabled the mechanization of mining and industrial production, railways and shipping. The steam engine was almost the only power source in the 19th century, but the steam engine and its boilers, condensers, and cooling water systems were bulky, heavy, and inconvenient to use.

At the end of the 19th century, power supply systems and electric motors began to develop and promote. At the beginning of the 20th century, electric motors replaced steam engines in industrial production and became the basic power for driving various working machinery. The mechanization of production is inseparable from electrification, and electrification plays a role in production through mechanization.

The steam engine was used as the driving force in the initial stage of the power station. At the beginning of the 20th century, high-efficiency, high-speed, high-power steam turbines appeared, as well as water turbines adapted to various water resources, which promoted the vigorous development of power supply systems.

The internal combustion engine invented in the late 19th century has been improved year by year and has become the prime mover that is light, small, efficient, easy to manipulate, and can be started at any time. It was first used to drive land-based working machinery that had no power supply. Later, it was used in automobiles, mobile machinery, and ships, and it was used in railway locomotives in the mid-20th century.

The steam engine is no longer an important power machine due to the displacement of the steam turbine and internal combustion engine. The development of the internal combustion engine and the gas turbine and jet engine invented later is one of the basic technical factors for the successful development of aircraft and spacecraft.

Before the Industrial Revolution, most of the machinery was made of wood, which was made by woodworkers. Metals (mainly copper and iron) are only used to make small parts on instruments, locks, clocks, pumps and wooden machinery. Metal processing mainly relies on the meticulous workmanship of the mechanic to achieve the required precision.

The promotion of steam engine power units, and the subsequent development of large-scale machinery such as mines, metallurgy, ships, locomotives, etc., require more and more metal parts to be formed and cut, and they require more and more precision. high. The applied metal materials have developed from copper and iron to mainly steel.

Mechanical processing includes forging, forging, sheet metalworking, welding, heat treatment and other technologies and equipment, as well as cutting processing technology, machine tools, cutting tools, and measuring tools. The rapid development has ensured the supply of mechanical equipment required for the development and production of various industries.

With the development of social economy, the demand for mechanical products has soared. The increase in production batches and advances in precision processing technology have promoted the formation of a large number of production methods, such as interchangeable production of parts, specialized division of labor and collaboration, assembly lines and assembly lines.

Simple interchangeable parts and specialized division of labor and collaborative production have appeared in ancient times. In mechanical engineering, interchangeability was first reflected in the bolts and nuts produced by Motzley in 1797 with the thread lathe he created.

In the same period, American engineer Whitney used interchangeable production methods to produce firearms, showing the feasibility and superiority of interchangeability. This production method is gradually popularized in the United States, forming the so-called “American production method.”

A brief history of mechanical development, after the 20th century

At the beginning of the 20th century, Ford created assembly lines in automobile manufacturing. Mass production technology combined with the scientific management method established by Taylor at the end of the 19th century enabled the production efficiency of automobiles and other mass-produced mechanical products to quickly reach a height that was unimaginable in the past.

In the middle and late 20th century, the main characteristics of machining are: continuously improve the processing speed and accuracy of machine tools, reduce dependence on manual skills; improve the mechanization and automation of forming, cutting and assembly; use CNC machine tools, machining centers, Group technology, etc., develop flexible processing systems to improve the production efficiency of small and medium batches and multi-variety production to a level close to mass production; research and improve the forming and cutting technology of new metal and non-metal materials that are difficult to process.

Before the 18th century, machinists relied solely on experience, intuition and craftsmanship to make machinery, and had little contact with science. In the 18th to 19th centuries, under the promotion of the emerging capitalist economy, people with scientific knowledge began to pay attention to production, while the craftsmen who directly engaged in production began to learn scientific and cultural knowledge. The exchanges and mutual inspiration between them have achieved great results. The results. In this process, a set of basic theories surrounding mechanical engineering has gradually formed.

Power machinery was first combined with the advanced science of the time. Savery and Watt, the inventors of the steam engine, applied the theories of the physicists Papan and Black; on the basis of the practice of the steam engine, the physicists Carnot, Rankin and Kelvin established a new science-thermodynamics.

The theoretical basis of the internal combustion engine was founded by France’s Rocha in 1862; in 1876, Otto applied Rocha’s theory to completely improve the crude, heavy, noisy, and low thermal efficiency internal combustion engine he originally created and established the position of the internal combustion engine. Others such as steam turbines, gas turbines, water turbines, etc. have been developed under the guidance of theory, and theories have also been improved and improved in practice.

As early as BC, China had applied a complicated gear system to the guide car, and used parts such as a cross turret that could permanently maintain the horizontal position in the quilt incense burner. There have been records of cylindrical gears, bevel gears and worm drives in ancient Greece. However, the relationship between the instantaneous speed ratio of the gear transmission and the tooth profile and the selection of the tooth profile curve were not theoretically explained until after the 17th century.

Hand crank and pedal mechanism are the pioneers of crank and connecting rod mechanism, and have a long history in ancient civilizations, but the exact analysis and synthesis of the form, movement and power of crank and connecting rod mechanism are the achievements of modern mechanism.

Institutional science, as a specialized subject, was first included in the courses of higher engineering schools as late as the early 19th century. Through theoretical research, people can accurately analyze various mechanisms, including the movement of complex spatial linkages, and then synthesize new mechanisms as needed.

The working object of mechanical engineering is dynamic machinery, and its working conditions will change greatly. This change is sometimes random and unpredictable; the actual materials used are not completely uniform, and there may be various defects; there are certain deviations in processing accuracy, and so on.

Compared with civil engineering, which takes static structure as the work object, various problems in mechanical engineering are more difficult to solve accurately with theory. Therefore, the early mechanical engineering only used simple theoretical concepts and combined practical experience to work.

Design calculations mostly rely on empirical formulas; in order to ensure safety, they are all conservative. As a result, the resulting machinery is heavy and large, with high cost, low productivity and high energy consumption.

Since the 18th century, the continuous birth of new theories and the development of mathematical methods have continuously improved the accuracy of design calculations. In the 20th century, various experimental stress analysis methods have appeared, and people have been able to measure the stress of various parts of the model and the physical object by experimental methods.

In the second half of the 20th century, the wide application of finite element methods and electronic computers made it possible to analyze and calculate the forces, moments, and stresses of complex machinery and its parts and components.

For machinery or its components that have sufficient practical or experimental data, statistical techniques can be used to scientifically design machinery in accordance with the required reliability.

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