Machines are tools and devices that can help people reduce the difficulty or save labor. Objects such as chopsticks, brooms and tweezers can be called machines. They are simple machines.Complex machinery is composed of two or more simple machines.These complex machines are usually called machines.From the point of view of structure and motion, there is no difference between mechanism and machine, which is generally called machinery.
Chinese name
Mechanics
Foreign name
machinery
Definition
Refers to the general name of machines and mechanisms
The word "machine" originates from Mechine in Greek and Machina in Latin. The earliest definition of "machine" is ancient Roman architectVitruvius(Vitruvii) In his book Ten Books of Architecture, he mainly made a distinction between machinery and tools for carrying heavy objects: "There seems to be the following difference between machinery (machine) and tools (organon). That is, machinery works with most manpower and great power, such as heavy catapults andGrapepress.The tools, such as scorpion shaped catapult or unequal circle spiral device, are handled carefully by an operator to achieve the goal.Therefore, tools and machinery are indispensable for utilization.ancient GreekCylindrical gears have existed in this period.Heron of Alexandria first discussed the basic elements of machinery in the first century. He believed that there were five types of mechanical elements: wheel and shaft, lever,Pulley, wedge, spiral.Hero's exposition reflects the characteristics of classical machinery.In ancient ChinaIncense burnerThe cross turret and other parts that can permanently maintain the horizontal position are used in the.
In his《MechanismThe Principle of Mechanism (1841) gives the definition that "any machine is composed of a group of components connected in various ways to make one of its components move, and the other components will move to some extent. The relative motion relationship between these components and the initially moving components depends on the nature of their connection." German mechanistReuleaux (F. Reuleaux) in his Theorykinematics》(Theoretische Kinematik, Grundz ü ge einer Theme des Maschienenwesens, 1875) defines as: "A machine is a combination of several objects with resistance, and its configuration mode makes it possible to use them to force the mechanical force of nature to do work, accompanied by a certain definite motion."
In general, machinery is a tool device that can help people reduce the difficulty or save labor. Objects such as chopsticks, brooms and tweezers can be called machinery. They are simple machines.Complex machinery is composed of two or more simple machines.These complex machines are usually called machines.
Chinese Concept and Source
Chinese Concept and Source
Mechanics[3]
The word "mechanical" consists of two Chinese characters, "mechanical" and "mechanical"."Machine" - originally refers to local key parts;"Machinery" - in ancient China, it originally refers to a whole instrument or appliance.When these two words are combined to form the word "machinery", they form a general concept of machinery.
“machine”In ancient Chinese, it originally refers to some kind of specific device, and later refers to general machinery.《Shangshu·Taijia has a saying that "if Yuji Zhang goes to the province to cover the degree, then he will explain it".Zhuangzi Qi Wu Lun: "Its hair is like a machine." Shiwen says: "Machine is the tooth of a crossbow; it is a arrow."《Analytical Dictionary of Characters》Yes“machine”The explanation of "machine" is "the main engine", referring to the crossbow machine.Zhuangzi Mountain Forest said: "Fenghu, Wenbao... are not free from the trouble of snaring machines", that is, devices such as clamps.Ancient“Mechanistic expression”Refers toloom。According to Huai Nanzi · Fan Lun, "Bo Yu made clothes at the beginning of his life,... when he hung his hands on his fingers, they became a snare. Later generations used the opportunity to express victory and recovery so that they could use it."《Redords of the Grand History of China·In the Biography of Li Sheng, it is said that "the farmer releases Lei, and the second daughter gets off the plane".It can be seen from this that the original meaning of "machine" refers to the rotating components that constitute the rotating pair in the mechanical device.
“Machinery”In ancient China, it refers to instruments, utensils and other objects.Chuang Tzu · Heaven and Earth records that "there are weapons here, which can be used to soak hundreds of beds a day, with little effort and much success". The "weapons" here are general instruments or appliances;Mozi · Public Transportation: "Public transportation is like making weapons for Chu", which refers to weapons here;According to the Book of Han · Biography of Sima Qian, "Huaiyin (Han Xin), Wang Ya, received the weapon in Chen". Here, "weapon" refers to the instrument of torture.
《Zhuangzi·In the outer part, the twelfth chapter of heaven and earth, "... Zigong said: 'There is a weapon here. One day, he soaks hundreds of beds. With little effort, he gets more achievements. What do you want?' The nurseryman looked up to him and said, 'Why?' He said: 'Cutting wood is a machine. It's heavy in the back and light in the front. Holding water as if drawing, and counting as if soup. Its name is Gao.’The man who worked for the garden scowled and said, 'I heard of my teacher. If there is machinery, there must be organic matter, and if there is organic matter, there must be tact.If you are alert in your heart, you are unprepared.If you are unprepared for pure white, you will be uncertain.God is born in uncertainty, which is not contained in the Tao.I don't know, but I'm ashamed not to do it. 'Zi Gong kept it from him and bent over him. "This dialogue defined the concept of machinery for Zi Gong's dialogue with the old man, that is, "machinery is a device that can exert little force but can do much good".There is a similar statement in the second chapter of the 15th volume of Han Feizi's "Difficulties": "It is based on the advantages of terrain, boats and machinery. If you use less force and make great contributions, you will enter more." Therefore, China has formed a modern society at the latest in the Warring States PeriodMechanical Engineering"Machinery" is a concept with similar meaning.
Modern machinery
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1. Machinery is a combination of objects, and it is difficult to deform when the pseudo force is applied to each part.
2. These objects must realize mutual, single and specified movement.
3. Transform the applied energy into the most useful form, or into effective mechanical work.
The definition of mechanism and machine comes fromMechanical Engineering, which belongs to the most basic concept in modern mechanical principles. The modern concept of Chinese machinery is mostly derived from the Japanese word "machinery".
Everything is certainMotion systemThe general name of machines and mechanisms of.For example:Machine tool, tractors, etc.
Mechanical engineering is an applied discipline that studies and solves theoretical and practical problems in the development, design, manufacturing, installation, application and repair of various machines based on relevant natural and technical sciences and combined with the technical experience accumulated in production practice.
The development of various engineering fields requires the development of mechanical engineering, which needs to provide the necessary machinery.The invention and improvement of some machinery will lead to the emergence and development of new engineering technology and new industries.For example, the successful manufacture of large power machinery has contributed to the establishment of the power system;The invention of the locomotive led torailway engineeringAnd the rise of the railway industry;Internal combustion enginegas turbine、rocket engineThe invention and progress of, and the successful development of aircraft and spacecraft led to the rise of aviation and aerospace;The development of high pressure equipment has led to the success of many new synthetic chemical engineering.
Mechanical engineering is the ability to obtain development impetus under the pressure of constantly increasing demand in all aspects, and to improve and innovate from the progress of various disciplines and technologies.
Machinery is a simple device that can transfer energy and force from one place to another.It can change the shape and structure of objects to create new objects.In life, there are countless different kinds of machines working for us.
The daily understanding of machinery is mechanical devices, that is, various machines andapparatus。
From the perspective of machinery specialty, machinery has a very important basic position.
Machinery is the five major production and service in modern societyessential factor(i.e. people, capital, energy, materials and machinery).
When Marx talked about industrial society, he saidindustrial society, especially in the big industrial society, that is, the era of using machines to produce machines.
No matter various physical devices contacted from life, such aselectric light, telephones, televisions, refrigerators, elevators and so on all contain the components of machines, or are included in the broad sense of machinery. From the perspective of production, all kinds of machine tools, automation equipment, aircraft, ships, Shenzhou, Shenzhou, Shenzhou, Shenzhou, and so on cannot lack machinery.
Therefore, machinery is a foundation of modern society.If someone wants to say that agriculture is also the foundationno ground for blameHowever, in modern society, machinery, as the foundation of the whole industry and engineering, can be regarded without exaggeration as a big part of the societycolumn。
Any modern industry and engineering field needs to apply machinery, that is, people's daily life. More and more machines are also used, such as cars, bicycles, clocks, watchescamera, washing machine, refrigeratorair conditioning equipment、Vacuum cleanerwait.
Main features
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Machinery is a combination of artificial physical components.There are certainrelative motion。In addition to the features of mechanism, the machine must also have the third feature, that is, it can replace human labor to complete useful mechanical work or conversionmechanical energy, so a machine can convert mechanical energy or complete useful mechanical work.From the point of view of structure and motion, there is no difference between mechanism and machine, which is generally called machinery.
Fluid transmission and control (including pneumatic hydraulic control technology, etc.)
Mechanical manufacturing automation
Numerical control technology
Industrial robot technology
Computer Aided Manufacturing
Power mechanical engineering
Other disciplines of mechanical engineering
Main categories
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There are many kinds of machinery, which can be divided into various categories according to several different aspects, such as: power machinerymaterial handling machinery 、Crushing machineryEtc;According to the service industry, it can be divided into agricultural machinery, mining machinery, textile machineryPackaging machineryEtc;According to the working principle, it can be divided intoThermomechanical, fluid machinerybio-simulation machinery Etc.
The main products of China's machinery industry include the following 12 categories:
petrifactionGeneral machinery: oil drilling and production machinery, oil refining machineryChemical machinery, pump, fan, valveGas compressor, refrigeration and air conditioning machinery, paper making machineryPrinting machinery, plastic processing machinery, pharmaceutical machinery, etc;
Electrical machinery: power generation machinery, transformers, high and low voltage switches, wires and cables, batteries, welding machines, household appliances, etc;
Environmental protection machinery: water pollution prevention equipment, air pollution prevention equipment, solid waste treatment equipment, etc;
Mining machinery:Rock splitter, stone jacking machine, etc.
Construction machinery refers to the general term of construction machinery used for engineering construction.It is widely used in construction, water conservancy, power, roads, mines, ports, national defense and other engineering fields.
There are many kinds of construction machinery, which are mainly divided into:
excavating machinery: e.gSingle bucket excavator(It can also be divided into crawler excavator and tyre excavator), multi bucket excavator (it can also be divided into wheel bucket excavator and chain bucket excavator), multi bucket trencher (it can also be divided into wheel bucket trencher and chain bucket trencher), rolling excavator, milling excavatorTunnel boring machine(including shield trench machinery and roadheader);
Earth moving machinery: such as bulldozers (also divided into tire type bulldozers and crawler type bulldozers), scrapers (also divided into crawler type self-propelled scrapers, tire type self-propelled scrapers and towed scrapers), loaders (also divided into tire type loaders and crawler type loaders), graders (also divided into self-propelled graders and towed graders)Transport vehicles (including single axle transport vehicles and double axle traction transport vehicles), flat cars and dump trucks;
Other construction machinery: such as bridge erecting machine, pneumatic tools (pneumatic tools), etc.
Mechanical drawing
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Mechanical drawingIt is a discipline that uses drawings to accurately express the structural shape, size, working principle and technical requirements of machinery.Drawings are composed of graphics, symbols, characters and numbers. They are technical documents that express design intent, manufacturing requirements and exchange experience. They are often called the language of engineering.[1]
The origin of using pictures to record events is very early. For example, the New Instrument Image Fayao written by Su Song and Zhao Gonglian in the Song Dynasty of China has been attached with the drawings of astronomical time reporting instruments, and the Tiangong Kaiwu written by Song Yingxing in the Ming Dynasty also has a large number of mechanical drawings, but it is not yet rigorous.
In 1799, French scholar Monge published his work Descriptive Geometry. Since then, figures in mechanical drawings have been drawn in strict accordance with the projection theory of descriptive geometry.In order to enable people to have a consistent understanding of the format, characters, lines, graphic simplification and symbol meanings involved in the drawings, a unified specification was gradually formulated and developed into a mechanical drawing standard.Each country generally has its own national standards, and there areInternational Organization for StandardizationStandards developed.China's national standard for mechanical drawing was formulated in 1959, and then revised twice in 1974 and 1984.
The items specified in the mechanical drawing standards include: drawing size and format, scale, font, lines, etc.The size of the standard size of the drawing and the corresponding size of the frame in the drawing are specified in the drawing size and format.The scale refers to the ratio between the size length in the drawing and the actual size of the parts. Except for 1:1, only the reduced scale and enlarged scale specified in the standard are allowed to be used for drawing.
In China, it is stipulated that Chinese characters must be written in long imitation Song style, and letters and numbers must be written in the prescribed structure.There are eight specifications for drawing lines, such as thick and solid lines for drawing visible contour lines, dotted lines for drawing invisible contour lines, fine dotted lines for drawing axes and symmetrical centerlines, and fine and solid lines for drawing dimension lines and section lines.
Mechanical drawings mainly includeParts drawingandAssembly drawingIn addition, there are layout drawingsSketch MapAnd shaft drawing, etc.Part drawings express the shape and size of parts and the technical requirements for manufacturing and inspecting parts;The assembly drawing represents the assembly relationship and working principle between the parts and components in the machine;The layout shows the location of mechanical equipment in the plant;The schematic diagram expresses the working principle of the machine, such as the schematic diagram of the mechanism movement that expresses the mechanical transmission principle, the schematic diagram of the pipeline that expresses the liquid or gas transmission line, etc.All mechanical components in the schematic diagram are represented by symbols.Axis drawing is a kind of stereoscopic drawing with strong intuition, which is commonly used as an auxiliary drawing.
The commonly used graphics to express the shape of mechanical structure areview、cutaway viewandprofileEtc.
A view is a figure obtained by projecting the machine part onto the projection plane according to the orthographic projection method.According to different projection directions and positions of corresponding projection planes, views are divided into main view, top view, left view, etc.The view is mainly used to express the external shape of the machine part.The invisible contour lines in the figure are represented by dotted lines.When a part projects to the projection plane, there are two relative positions between the observer, the part and the projection plane.The first angle projection method is called when the machine part is located between the projection plane and the observer.When the projection plane is between the machine and the observer, it is called the third angle projection method.Both projection methods can perfectly express the shape of parts.Chinese National StandardThe first angle projection method is specified.
The section view is an imaginary part cut with a section plane. The part between the observer and the section plane is removed, and the rest is projected to the projection plane to obtain a figure.The section view is mainly used to express the internal structure of the machine parts.The section drawing only draws the figure of the cutting section.The sectional drawing is often used to express the sectional shape of the rod structure.
For some complicated structures in drawings, simplified drawing is allowed to improve drawing efficiency. The simplified drawing is called simplified drawing.Mechanical drawing standards have independent standards for the drawing method of thread, gear, spline, spring and other structures or parts.
The drawings are drawn according to the structural shape and size of the machine parts in proper proportion.The dimensions of the parts in the drawing shall be indicated with dimension lines, extension lines and arrows, and the size shall be indicated with numbers.In the mechanical drawing, the unit of figures is specified as mm, but it is unnecessary to indicate.For dimensions such as diameter, radius, taper, slope and arc length, symbols shall be added before the numbers for explanation.
When manufacturing machine parts, they must be processed according to the dimension numbers marked in the drawing, and it is not allowed to directly measure the dimension of the drawing from the drawing.Technical conditions required to be met in mechanical manufacturing, such as tolerance and fit, geometric toleranceSurface roughnessMaterials and their heat treatment requirements shall be marked with symbols, words and numbers in the drawings according to the mechanical drawing standards.
Before the 20th century, drawings were all hand drawn with general drawing tools.At the beginning of the 20th century, the mechanical structure plotter appeared, which improved the efficiency of drawing.In the second half of the 20th century, computer drawing appeared. The drawings to be drawn were programmed into an electronic computer, and then the computer converted them into graphic information, which was sent to the plotter to draw the drawings, or sent to the computer controlledAutomatic machine toolProcessing.
Generally, the drawings need to be depicted as transparent base drawings, which can be used to develop blueprints or ammonia smoked purple drawings.In the middle of the 20th centuryElectrostatic copier, the copier can directly copy the original drawing, and can enlarge or reduce the drawing.Using this new technology can save the tracing process.
Mechanical seal
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Mechanical sealAlso called face seal, it is mainly used to seal the rotating shaft of pumps, compressors, hydraulic transmission and other similar equipment.The mechanical seal is a sealing device consisting of a pair of pairs of plane friction pairs composed of a pair of moving rings and several pairs of stationary rings.
The mechanical seal is a device to prevent fluid leakage, which is composed of at least one pair of end faces perpendicular to the rotation axis under the action of fluid pressure and the elastic force (or magnetic force) of the compensation mechanism and the cooperation of the auxiliary seal.The auxiliary seal of the compensation ring isMetal bellowsIs called bellows mechanical seal.
form
There are four main types of components:
1. Main seals: dynamic ring and static ring;
2. Auxiliary seal: seal ring;
3. Presser: spring, push ring;
4. Transmission parts: skip seat and key or fixing screw.
classification
According to the rotation or standstill of spring elements, it can be divided into: rotary inner flow non-equilibrium single face seal, referred to as rotary type;Static external and internal flow balanced single face seal is called static for short.
The stationary ring can be divided into internal and external type according to its location inside or outside the sealing face;
According to the leakage direction of sealing medium, it can be divided into: internal loss and external flow;
According to the unloading caused by the media on the end face, it can be divided into: balanced and unbalanced;
According to the logarithm of sealing face, it can be divided into: single face and double face;
According to the number of springs, it can be divided into: single spring type and multi spring type;
Classified by elastic elements: spring compression type and bellows type;
Classification according to non-contact mechanical seal structure: hydrostatic, hydrodynamic, dry gas seal;
Classification according to the temperature of sealing chamber: high, medium, common and low temperature sealing;
Separation according to the pressure of sealing chamber: ultra-high, high, medium and low pressure mechanical seal;
matters needing attention
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Precautions during installation:
1. Pay great attention to avoid installation deviation during installation.
1) The gland shall be tightened after the alignment of the coupling. The bolts shall be evenly supported to prevent the end face of the gland from deflecting. Check each point with a feeler gauge, and the error shall not be greater than 0.05 mm;
2) Check the fit clearance (i.e. concentricity) between the gland and the outer diameter of the shaft or shaft sleeve. The circumference should be even. Use a feeler gauge to check that the tolerance of each point is not more than 0.01mm.
2. The spring compression shall be carried out according to the regulations, and it is not allowed to be too large or too small. The required error is 2.00mm.If it is too large, the end face pressure will be increased, and the end face will be worn at another speed.If it is too small, the specific pressure will be insufficient and the sealing effect will not be achieved.
3. The movable ring shall be able to move flexibly on the shaft after installation, and it shall spring back automatically after pressing the movable ring against the spring.
Precautions during disassembly:
1. When disassembling the mechanical seal, be careful. Never use a hammer or flat shovel to avoid damaging the sealing elements.It can be used as a pair of steel wire hooks to extend into the notch of the transmission seat in the direction of self financing and pull out the sealing device.If scaling cannot be removed, it shall be cleaned before removal;
2. If mechanical seals are used at both ends of the pump, take care of each other in the process of assembly and disassembly to prevent one thing from losing another;
3. For the operated mechanical seal, if the gland is loose and the seal moves, the moving and stationary ring parts must be replaced and should not be tightened again for further use.Because the original running track of the friction pair will change after the sample movement, the sealing of the contact surface will be easily damaged.
Normal operation and maintenance of mechanical seal:
1. Preparations and precautions before startup
1) Comprehensively check whether the mechanical seals, auxiliary devices and pipelines are installed completely and meet the technical requirements;
2) Static pressure test shall be carried out before starting the mechanical seal to check whether there is leakage of the mechanical seal.If there are many leaks, find out the causes and try to eliminate them.If it is still invalid, it shall be disassembled, checked and reinstalled.The general hydrostatic test pressure is 2-3 kg/cm2;
3) Turn the gear according to the rotation direction of the pump and check whether it is light and even.If the turning gear is hard or does not move, check whether the assembly size is wrong and the installation is reasonable.
2. Installation and shutdown
1) The sealing chamber shall be kept full of liquid before starting.When transporting solidified medium, the sealing chamber shall be heated by steam to melt the medium.The turning gear must be turned before starting to prevent the soft ring from breaking due to sudden starting;
2) For the mechanical seal using the external sealing oil system of the pump, the sealing oil system shall be started first.Stop the oil sealing system finally after shutdown;
3) After the hot oil pump is shut down, the cooling water of the seal oil chamber and the end face seal cannot be stopped immediately. The cooling water can only be stopped when the oil temperature at the end face seal drops below 80 degrees to avoid damaging the sealing parts.
3. Operation
1) If there is slight leakage after the pump is started, observe for a period of time.If the leakage does not decrease after 4 hours of continuous operation, stop the pump for inspection;
2) The operating pressure of the pump shall be stable, and the pressure fluctuation shall not be greater than 1 kg/cm2;
3) During the operation of the pump, evacuation shall be avoided to avoid dry friction on the sealing surface and seal damage;
4) The sealing condition shall be checked frequently.During operation, when the leakage exceeds the standard, the heavy oil shall not be more than 5 drops/min and the light oil shall not be more than 10/min. If there is no improvement trend within 2-3 days, the pump shall be stopped and the sealing device shall be checked.
mechanical engineering
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Mechanical engineering: an applied discipline that studies and solves all theoretical and practical problems in the development, design, manufacturing, installation, application and repair of various machines based on relevant natural and technical sciences and combined with technical experience in production practice.Machinery is one of the five major factors (people, capital, energy, materials and machinery) for production and service in modern society, and participates in the production of energy and materials.
Brief history of mechanical engineering:
Various stone axes, hammers and simple tools made of wood and leather, which were manufactured and used by human beings in the Stone Age, were the pioneers of machinery later.Thousands of years ago, human beings have created mortar and mill for grain hulling and crushing, shaddock and windlass for water lifting, cars with wheels, boats sailing in rivers, oars, sculls, rudders, etc.The power used has developed from human power to animal power, wind power and water power.The materials used have developed from natural stone, wood, soil, leather, etcArtificial material。The earliest artificial material was ceramics.The pottery cart for making ceramic utensils is a complete machine with three parts: power, transmission and work.The blower has played an important role in the development of human society.The powerful blower enables the metallurgical furnace to obtain high enough furnace temperature to extract metal from ores.In the Western Zhou Dynasty, China already had a blast apparatus for smelting and casting.Before the 15th and 16th centuries, mechanical engineering developed slowly.After the 17th century,Capitalist commodity economyWith the rapid development in Britain, France and other countries, many people are committed to improving the working machinery needed by various industries and developing new power machinery - steam engines.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 gradually changed from wood to metal.Machinery manufacturing industry began to form 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 capitalist machinery production 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, relying only on human and animal power can no longer meet the requirements of production improvement, so T. Newcomen's atmospheric steam engine appeared in the early 18th century to drive the mine drainage pump.In 1765, J. Watt invented the steam engine with separate condenser, which reduced the fuel consumption rate.In 1781, Watt created a steam engine to provide rotary power, expanding the application range of steam engines.The invention and development of the steam engine have promoted the dynamic development of mining and industrial production, railways and handling machinery.It almost became the only power source in the 19th century.But the steam engine and its boiler, condenser and cooling water system are bulky and bulky, which is inconvenient to use.The steam engine is used as the prime mover in the initial stage of the power station;At the beginning of the 20th century, steam turbines with high efficiency, high speed and high power appeared, as well as large and small power turbines adapted to various hydraulic resources.After years of improvement, the internal combustion engine invented in the late 19th century has become a light, small, efficient, easy to operate and ready to start prime mover.The internal combustion engine was initially used to drive land working machinery without power supply, and later used in automobiles, mobile machinery (such as tractors, excavation machinery, etc.) and ships. It began to be used in railway locomotives in the middle of the 20th 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 wooden structures made by hand by carpenters, and metal (mainly steel and iron) was only used to make small parts on instruments, clocks, locks, pumps and wooden structure machinery.Metal processing mainly depends on the precision of machinists to achieve the required precision.With the widespread use of steam engines and the subsequent development of large machinery such as mines, metallurgy, ships and locomotives, themetal partsMore and more metal materials are used, from copper and iron to steel.The rapid development of machining (including casting, forging, welding, heat treatment and other technologies and equipment, as well as cutting technology and machine tools, cutting tools, measuring tools, etc.) has ensured the supply of various mechanical equipment required for the development of production.At the same time, with the increase of production batch and the development of precision machining technology, it has also promoted the formation of a large number of production methods (parts interchangeability production, professional division of labor and cooperation, flow processing line and flow assembly line, etc.).
Development of basic theory of mechanical engineering:
Before the 18th century, machinists made machines based on their personal experience, intuition and craftsmanship, which had nothing 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, the inventor of the steam engine, and D. Papan and J. Blake, the applied physicists of Watt. Physicists S. Kano, W.J.M. Rankin and Kelvin established a new discipline thermodynamics based on the practice of the steam engine.At the beginning of the 19th century, mechanics, which studies the structure and movement of machinery, was for the first time listed as a course in the Higher Engineering Institute (the Polytechnic Institute in Paris).Since the second half of the 19th century, the fatigue of materials has been considered in design and calculation.Then fracture mechanics, experimental stress analysis, finite element method, mathematical statistics, and electronic computers were used in design calculations.
Service fields of mechanical engineering:
The service field of mechanical engineering is very wide. All departments that use machinery, tools and even energy and material 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, electrical 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 required;
2. To develop and provide machinery for the production of various products, including agricultural, forestry, animal husbandry, fishery machinery and mining machinery, as well as various heavy and light industrial machinery;
3. Develop and provide machinery for various services, such as material handling machinery, transportation machinery, medical machinery, office machinery, ventilation, heating and air conditioning equipment, dust removal, purification, noise elimination and other environmental protection equipment;
4. Develop and provide household and personal living machinery, such as washing machines, refrigerators, clocks, cameras, sports equipment and entertainment equipment;
5. Develop and provide various mechanical weapons.
Subject content of mechanical engineering
The discipline content of mechanical engineering can be divided into:
1. Establish and develop engineering theoretical basis that can be applied to mechanical engineering in practice and directly.Such as engineering mechanics, fluid mechanics, engineering materials, material mechanics, combustion, heat transfer, thermodynamics, tribology, mechanics, mechanical principles, mechanical parts, metal technology and non-metallic technology;
2. Research, design and develop new mechanical products, improve existing mechanical products and produce new generation mechanical products to meet current and future needs;
3. Production of mechanical products, such as planning and realization of production facilities, formulation of production plans and production scheduling, preparation and implementation of manufacturing processes, design and manufacturing process equipment, determination of labor quota and material quota, 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. To study the environmental pollution and excessive consumption of natural resources caused by the manufacturing and use of mechanical products and the treatment measures.
Disciplinary branches 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 industry, 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, same function or serving the same industry have the same problems and characteristics, so mechanical engineering has several different branch discipline systems.In addition, all machinery will go through several stages with different working properties in the process of research, development, design, manufacturing and application.
These subdisciplinary systems intersect and overlap each other, so that mechanical engineering may be divided into hundreds of subdisciplines.For example, power machinery classified by function, and thermal machinery, fluid machinery, turbine machinery, reciprocating machinerySteam power plant、Nuclear power plant, internal combustion engines, gas turbines, as well as central power station equipment, industrial power plants, railway locomotives, marine turbine engineeringAutomotive EngineeringThere are complex cross and overlapping relationships.Marine steam turbineIt is power machinery, thermal machinery, fluid machinery and turbine machinery, belonging toMarine power plant, steam power plant, or nuclear power plant.The clockwork and weight device used to drive the clock is also a power machine, but not a thermal machine, fluid machine, turbine machine or reciprocating machine.Other branches have similar overlapping and cross relationships.However, it has little practical value.
Outlook:
Machinery industry is the basic industry that provides equipment for the national economy, and will change with the development of science and technology.
Mechanical engineering to increase production and improve laborproductivityDevelop and develop new mechanical products with the goal of improving the economy of production.In the future, the development of new products will reduce resource consumption and develop cleanRenewable energyGovernance, mitigation and even elimination of environmental pollution are super economic goals.
Machines can complete tasks that people can or cannot directly complete with their hands and eyes, as well as feet and ears, and can be completed faster and better.Modern mechanical engineering has created more and more sophisticated machinery and mechanical devices, making many of the past fantasies come true.
Humans have been able to swim up the sky and the universe, dive deep into the ocean, and see tens of billions from afarLight year, closely observe cells and molecules.The emerging computer hardware and software science has strengthened human beings and partially replaced the scientific and technological means of human brain, which is artificial intelligence.This new development has shown great influence, and it will continue to create miracles that people cannot imagine in the coming years.
The growth of human intelligence does not reduce the role of hands, on the contrary, it requires hands to do more, more sophisticated and more complex 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, as well as in the process of everyone's growth, brain and hand promote each other and evolve in parallel.
The relationship between artificial intelligence and mechanical engineering is similar to the relationship between brain and hand. The difference is that the hardware of artificial intelligence needs to be manufactured by machinery.In the past, all kinds of machines could not be separated from human operation and control, and their reaction speed and operation accuracy were limited by the slow evolving human brain and neural system. Artificial intelligence will eliminate this limitation.The mutual promotion and parallel progress between computer science and mechanical engineering will enable mechanical engineering to start a new round of great development at a higher level.
In the 19th century, the total knowledge of mechanical engineering was still very largeLimitedIn European universities and colleges, it is generally integrated with civil engineering as a discipline, known as civil engineering. It gradually became an independent discipline in the second half of the 19th century.In the 20th century, with the development of mechanical engineering technology and the growth of the total amount of knowledge, mechanical engineering began to decompose, and specialized branches emerged one after another.In the middle of the 20th centurythe Second World WarThe period before and after the end reached the peak.
Since the total amount of knowledge of mechanical engineering has expanded to far beyond the individual's ability to master, it is impossible to view and plan the overall picture and situation of a slightly large-scale project, and narrow the scope of technical exchanges, hinder the emergence of new technologies and the overall progress of technology, and have poor adaptability to changes in external conditions.Experts in closed specialties have too narrow knowledge and too specialized in considering problems. It is difficult to cooperate and coordinate when working together, which is also not conducive to continuingself-taughtImprove.Therefore, since the middle and late 20th century, there has been a comprehensive trend.People pay more attention to the basic theory, broaden the professional field, and merge the over differentiated majors.
The repeated cycle of synthesis professional differentiation re synthesis is a reasonable and necessary process for knowledge development.Experts in different disciplines have both superb professional knowledge and sufficient comprehensive knowledge to understandunderstandThe problems of other disciplines and the overall appearance of the project can form a powerful collective working together.
Comprehensive and professional are multi-level.There are contradictions between synthesis 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 andEngineering technologyThere are also comprehensive and professional problems at a higher level and at a larger scale.
Mechatronics：
Mechatronics technology and Mechatronics products are collectively called after the introduction of microelectronic components and technologies into electromechanical products.Mechatronics technology, also known as mechanical microelectronics technology, is a system technology integrated with mechanical engineering, microelectronics technology, information processing technology and other technologies.Mechatronics product is a kind of multi-functional single or complete set device with software and hardware systems designed and produced by using mechatronics technology. It is usually composed of mechanical body, microelectronic device, sensor and actuator.Mechatronics technology involves mechanical engineering (such as mechanism, machining and precision technology), electrical and electronic technology (such as electromagnetism, computer technology and electronic circuit), and common technology (such as system technology, control technology and sensor technology).Electromechanical integration products are mainly used for commodity production (such as robots, automatic production lines and factories), commodity flow (such as CNC packaging machinery and systems, microcomputer controlled transportation machinery and CNC engineering machinery and equipment), commodity storage and sales (such as automatic warehouses, automatic weighing and sales and cash handling systems)Social service (such as automated office machinery, medical and environmental protection automation facilities, etc.) and electromechanical integration products for 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 the machinery industry.
It was first proposed by Japanese enterprises around 1970“Mechatronics technology”At that time, they named this concept "Mechatronics", which means the combination of applied mechanical technology and electronic technology.With the rapid development and wide application of computer technology, mechatronics technology has achieved unprecedented development. The overall decomposition into several interrelated technologies has become a comprehensive computer and information technologyAutomatic control technology, sensing detection technology, servo transmission technology and mechanical technology, forwardOptical electromechanical integration technology(Opto mechatronics) (Opto mechatronics) (Opto mechatronics) is developing in the direction, and its application scope is becoming wider and wider.
The electromechanical integration technology specifically includes the following contents:
1. Mechanical technology: mechanical technology is the basis of mechatronics. The focus of mechanical technology is how to adapt to mechatronics technology, and use other high and new technologies to update concepts, realize changes in structure, materials, and performance, and meet the requirements of reducing weight, reducing volume, improving accuracy, and improvingrigidityAnd requirements for improving performance.In the process of mechatronics system manufacturing, the classical mechanical theory and technology should rely on computer aided technology. At the same time, information exchange, access, calculation, judgment and decision-making, artificial intelligence technology, expert system technology, and neural network technology are all computer information processing technologies.
2. System technology: system technology refers to the organization and application of various related technologies based on the concept of the whole. From the perspective of the whole, it decomposes the whole into several interrelated functional units. Interface technology is an important aspect of system technology, which is the guarantee to realize the organic connection of various parts of the system.
3. Automatic control technology: it has a wide range. Under the guidance of control theory, the system is designedsystem simulation On site debugging, control technologies include high-precision positioning control, speed control, adaptive control, self diagnosis correction, compensation, reproduction, retrieval, etc.
4. Sensor detection technology: sensor detection technology is the sensory organ of the system and the key link to realize automatic control and adjustment.The stronger the function, the higher the automation program of the system.Modern engineering requires that sensors can quickly and accurately obtain information and withstand the test of harsh environment, which is the guarantee for electromechanical integration system to reach a high level.
5. Servo transmission technology: including electric, pneumatic, hydraulic and other types of transmission devices,servo systemIt is a conversion device and component to realize electrical signal to mechanical action, and has a decisive impact on the dynamic performance, control quality and function of the system.
Mechatronics system composition:
1. Mechanical body: mechanical body includes frame, mechanical connectionmechanical driveIt is the basis of mechatronics and plays the role of supporting other functional units in the system, transmitting motion and power.Compared with pure mechanical products, the technical performance of electromechanical integration system has been improved and its functions have been enhanced, which requires that the mechanical body can adapt to it in terms of mechanical structure, materials, processing technology, geometric dimensions, etc., and has the characteristics of high efficiency, multi-function, reliability, energy saving, small size, light weight, and beauty.
2. Detection and sensing part: the detection and sensing part includes various sensors and their signal detection circuits, whose function is to detect the changes of parameters related to itself and the external environment during the working process of the electromechanical integration system, and to transmit information to the electronicscontrol unit The electronic control unit sends corresponding control to the actuator according to the detected information.
3. Electronic control unit: the electronic control unit is also called to send out corresponding commands with rhythm to control the whole system purposefully.
4. Actuator: the function of the actuator is to drive the movement of mechanical parts according to the instructions of the electronic control unit.Actuator is a moving part, which is usually driven by electricity, air pressure and hydraulic pressure.
5. Power source: power source is the energy supply part of electromechanical integration products, and its role is toSystem controlIt is required to provide energy and power to the mechanical system so that the system can operate normally.The ways of providing energy include electric energy, pneumatic energy and hydraulic energy, with electric energy as the main energy.
Mechanical engineering and human living environment:
The development of engineering technology not only improves human material civilization and living standards, but also destroys the natural environment.Since the middle of the 20th century, the most prominent problem is the massive consumption of resources, especially energy, and environmental pollution.In the future, the development of new mechanical products will take reducing resource consumption, developing pure renewable energy, treating, reducing and even eliminating environmental pollution as important tasks.
Specialization and integration of mechanical engineering:
In the second half of the 19th century, mechanical engineering became an independent discipline.The decomposition trend reached its peak in the middle of the 20th century (around the end of the Second World War).Since the total amount of knowledge of mechanical engineering has expanded to far beyond one person's grasp, it is impossible to view and plan the overall picture and overall situation of a slightly large-scale project, narrow the scope of technical exchanges, hinder the emergence of new technologies and the overall progress of technology, and change external conditions (such as the emergence of new technologies, new materials and new products, the supply and price changes of materials and semi-finished products, etc.)Their adaptability is very poor.Therefore, from the middle and late 20th century, there has been a comprehensive trend in mechanical engineering.People pay more attention to basic theories, broaden professional fields, and merge over differentiated specialties.
machine design
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1. Multi function design of components
The so-called component multi-function is that a component has multiple functions and can produce multiple useful actions in the process of mechanism operation.For example, in the feeding mechanism, the pushing component has both the function of pushing in place and the function of positioning and clamping. In the clamping mechanism, the pressing component has both the function of pressing and positioning;In the mechanism of reciprocating motion, the travel switch actuates the component.It not only triggers the reverse movement of the mechanism, but also drives the counter to record.
The multifunctional design of components can make the structure simple, compact and dexterous, and make the mechanism stable and reliable.
2. Simple and reliable movement exchange mechanism
The design of the motion transformation mechanism should select a reasonable mechanism according to the functional requirements and technical conditions, so that the mechanism can simply and reliably realize the transformation of motion form and direction, and can easily adjust the force and working position.The selection of mechanism type should consider its inherent characteristics, for example, the reduction mechanism must have the function of labor saving and stable operation.On the contrary, the speed increasing mechanism is not labor-saving and stable, but has the function of increasing travel (or increasing angle) and time delay.
The service field of mechanical engineering is broad and multifaceted. All departments that use machinery, tools, and even energy and material production need mechanical engineering services.To sum up, modern mechanical engineering has five major service areas: development and supplyenergy conversion Machinery, the development and provision of machinery for the production of various products, the development and provision of machinery for various services, the development and provision of machinery for use in family and personal life, and the development and provision of various mechanical weapons.
No matter what field they serve, the work content of mechanical engineering is basically the same, mainly including:
Establish and develop the engineering theoretical basis of mechanical engineering.For example, engineering mechanics and fluid mechanics studying force and motion;Research Metals andNonmetalProperties of materials and their applicationsEngineering materialsLearning;Study the thermodynamics of generation, conduction and conversion of heat energy;Study the working principle, structure, design and calculation of various mechanical elements with independent functions, mechanical principles and mechanical parts science;Research on metal and non-metal forming and cuttingMetal TechnologyAnd non-metallic technology, etc.
Research, design and develop new mechanical products, constantly improve existing mechanical products and produce new generation mechanical products to meet current and future needs.
Production of mechanical products, including: planning and realization of production facilities;Formulation of production plan and production scheduling;Prepare and implement manufacturing process;Design and manufacture tools and moulds;Determine labor quota and material quota;Organize processing, assembly, commissioning, packaging and shipping;Effectively control the product quality.
Operation and management of machinery manufacturing enterprises.Machinery is generally a complex product assembled from many precision parts with unique forming and processing processes.The production batch includes single piece and small batch, medium batch and large batch, and even mass production.The sales target covers all industries, individuals and families.Moreover, the sales volume may fluctuate greatly under the influence of social and economic conditions.Therefore, the management and operation of machinery manufacturing enterprises are particularly complex, and the research on production management, planning and operation of enterprises also started from the machinery industry.
The application of mechanical products includes the selection, ordering, acceptance, installation, adjustment, operation, maintenance, repair and transformation of machinery and complete sets of mechanical equipment used in various industries to ensure the reliability and economy of mechanical products in long-term use.
Study the environmental pollution and excessive consumption of natural resources caused by mechanical products in the manufacturing process, especially in use, and their treatment measures.This is a particularly important task of modern mechanical engineering, and its importance is growing day by day.
Development History
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Before the 20th century
The symbol of human being becoming "modern man" is to make tools.Various stone axes, stone hammers and simple and rough tools made of wood and leather in the Stone Age were the pioneers of machinery later.It has gone through a long process from manufacturing simple tools to manufacturing modern machinery composed of multiple parts and components.
Thousands of years ago, humans have created mortar and mill for grain hulling and crushing, which are used to lift waterShaddockandWindlass, wheeled vehicles, boats sailing on rivers, oars, oarsrudderEtc.The power used has developed from human physical strength to the use of animal power, water power and wind power.The materials used have developed from natural stone, wood, soil and leather to artificial materials.The earliest artificial material is ceramics, which is used to make ceramic utensilspotter's wheelIt is a complete machine with power, transmission and work.
Human entered from the Stone AgeBronze Age, and then to the Iron Age, the development of the blower used to blow up the furnace fire played an important role.Only when there is a strong enough blower can the metallurgical furnace obtain a high enough furnace temperature to refine metal from ores.In the 18th Dynasty of ancient Egypt, Rekhmir (about 1450 BC) has used a pot shaped blower for smelting and casting.In China, there were blowers for smelting and casting from 1000 BC to 900 BC, and they gradually developed from human blowing to animal power andwaterBlow hard.
Before the 15th and 16th centuries, mechanical engineering developed slowly.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 later.After the 17th century, capitalism appeared in Britain, France and Western Europe, 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 is gradually changed from wood to metal that is more tough but difficult to process by hand.MechanicsManufacturing industryIt has begun to take shape and has become an important industry in decades.
Through expanding practice, mechanical engineering has gradually developed from a decentralized skill that mainly depends on the individual talents and skills of craftsmen into a systematic and independent engineering technology with theoretical guidance.Mechanical engineering contributed to the development ofindustrial revolution, as well as the main technical factors of capitalist machinery mass production.
Power is an important factor in the development of production.In the late 17th century, with the improvement and development of various machines and the increasing demand for coal and metal ores year by year, people felt that production could not be improved to a new stage relying on human and animal power.
In the UK, textileGrindingMore and more industries have set up workshops near rivers, and use 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 removed with a large amount of animal power.Under such production needs, Newcomen's atmospheric steam engine appeared in the early 18th century to drive the mine exhaustWater pump。But the fuel for this steam engineConsumption rateVery high, basically only used in coal mines.
In 1765,wattInvented separatecondenserThe steam engine reduces the fuel consumption rate.In 1781 Watt created a steam engine to provide rotary power, which expanded the scope of application of steam engines.The invention and development of the steam engine have enabled mining and industrial production, railways and shipping to be mechanically powered.The steam engine was almost the only power source in the 19th century, but the steam engine and its boiler, condensercooling water system It is bulky and bulky, so it is inconvenient to use.
At the end of the 19th century, power supply systems and motors began to develop and popularize.At the beginning of the 20th century, motors have replaced steam engines in industrial production and become the basic power to drive various working machines.The mechanization of production has been inseparable from electrification, and electrification plays a role in production through mechanization.
power stationThe steam engine is used as the prime power at the initial stage.At the beginning of the 20th century, steam turbines with high efficiency, high speed, and high power appeared, as well as those suitable for various water resourcesWater turbine, promoting the vigorous development of the power supply system.
The internal combustion engine invented in the late 19th century has been improved year by year, becoming light, small, efficient, easy to operate, and ready to startPrime mover。It was first used to drive the land working machinery without power supply, then used for cars, mobile machinery and ships, and began to be used for railway locomotives in the middle of the 20th century.Steam engine is no longer an important power machine due to the exclusion of steam turbine and internal combustion engine.Internal combustion engine and gas turbine invented laterJet engineThe development of is one of the basic technical factors for the successful development of aircraft and spacecraft.
Before the Industrial Revolution, most of the machines were made of wood by hand.Metal (mainly copperiron）It is only used to manufacture small parts on instruments, locks, clocks, pumps and wood structure machines.Metal processing mainly depends on the precision of machinists to achieve the required precision.Steam power plantWith the development of mining, metallurgy, ships, locomotives and other large machinery, more and more metal parts need to be formed and cut, and the required precision is higher and higher.The applied metal materials have developed from copper and iron to steel.
Machining includes forgingforging and pressing, sheet metal worker, weldingheat treatmentAnd its equipment, as well as cutting technology and machine toolstool, measuring tools, etc., have developed rapidly, ensuring the supply of machinery and 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 of production batch and the progress of precision machining technology have promoted the formation of a large number of production methods, such as partsInterchangeabilityProduction, professional division and cooperation, flow processing line and flow assembly line, etc.
Simple interchangeable parts and professional division of labor and collaborative production have appeared in ancient times.In mechanical engineering, interchangeability was first reflected in the thread created by Motili in 1797LatheBolts and nuts produced.At the same time, American engineer Whitney used the interchangeability production method to produce the gun, showing the feasibility and superiority of interchangeability.This method of production was gradually popularized in the United States, forming the so-called "American production method".
After the 20th century
In the early 20th century,FordIn automobile manufacturing, it has created assembly line.Mass production technology and Taylor's scientific management method at the end of the 19th century made the production efficiency of automobiles and other mass-produced mechanical products quickly reach an unimaginable height in the past.
In the middle and late 20th century, the main characteristics of machining are: continuously improving the processing speed and accuracy of machine tools, reducing the dependence on manual skills;Improve the mechanization and automation of forming, cutting and assembly;utilizenumerical control machine、machining center , group technology, etc., and develop flexible processing systems to improve the production efficiency of small and medium-sized batch and multi variety production to the level of mass production;Research and improve new difficult to process metals andNon metallic materialsForming and cutting technology.
Before the 18th century, machinists made machines based on experience, intuition and craftsmanship, and had little connection with science.In the 18th and 19th centuriescapitalist economyUnder the promotion of, people who master scientific knowledge began to pay attention to production, while craftsmen who directly carry out production began to learn scientific and cultural knowledge, and their exchanges and mutual inspiration achieved great results.In this process, a set of basic theories around mechanical engineering has gradually formed.
Power machinery was first combined with the advanced science at that time.Inventor of the steam engineSafari、watt, applying the theories of physicists Pampa and Blake;On the basis of steam engine practice, physicists Kano, Rankin andKelvinEstablish a new science——thermodynamics。The theoretical basis of the internal combustion engine was founded by Rosa de France in 1862;In 1876, Otto applied Rosa's theory to thoroughly improve the crude, heavy, noisy and low thermal efficiency internal combustion engine he had created, and established the position of internal combustion engine.Others, such as steam turbine, gas turbine and water turbine, have been developed under the guidance of theory, and the theory has also been improved and enhanced in practice.
As early as BC, China had applied complex gear systems to guide carsIncense burnerThe cross turret and other parts that can permanently maintain the horizontal position are used in the.Ancient Greececylindrical gear、Bevel gearandworm driveRecords.However, with regard to gear transmission transientspeed ratioThe relationship with tooth profile and the selection of tooth profile curve were not theoretically expounded until after the 17th century.
The handle and pedal mechanism areCrank connecting rod mechanismThe forerunners of the mechanism have a long history in ancient civilizations, but the exact analysis and synthesis of the form, motion and power of the crank linkage mechanism are the achievements of modern mechanism science.As a specialized discipline, mechanism was first listed in the early 19th centuryHigher Engineering CollegeCourses.Through theoretical research, people can accurately analyze various mechanisms, including complexSpatial linkage And can 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 materials used in practice are also incompleteuniformity, there may be various defects;The machining accuracy has certain deviation, etc.
Compared with civil engineering, which takes static structure as its working object, various problems in mechanical engineering are more difficult to be solved accurately by theory.Therefore, early mechanical engineering only used simple theoretical concepts and combined with practical experience to work.Design calculation depends onEmpirical formula；To ensure safety, they are conservative, resulting in heavy and huge machinery, high cost, low productivity, and large energy consumption.
Since the 18th century, the 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 appeared, and people have been able to use experimental methods to measure the stresses in various parts of models and objects.
In the second half of the 20th centuryFinite element methodandelectronic computerThe wide application ofmoment、stressIt is possible to analyze and calculate.For machinery or its components with sufficient practical or experimental data, statistical technology can be used to scientifically design machinery according to the required reliability.
Development trend
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The development of construction machinery is an important equipment for national economic construction, and plays a pivotal role in the equipment industry.The sales revenue of China's construction machinery industry in 2007 was 222.3 billion yuan, ranking second in the world's construction machinery industry.From 2001 to 2007, the average annual growth rate exceeded 24%.The export volume increased from 224 million US dollars in 1998 to 8.7 billion US dollars in 2007, an increase of 37 times in 10 years. China's construction machinery industry occupies an important position in the global peers. Its products have been exported to Europe, America and other construction machinery powers, and is moving towards a "manufacturing power" and a "manufacturing power".
However, compared with the international advanced level, the overall level of China's construction machinery still lags behind, and some products are in the second and third class in the international mainstream market;Compared with large multinational construction machinery enterprise groups, Chinese construction machinery enterprises are still relatively weak in competitiveness.In the journey to become a powerful construction machinery manufacturing country, the development situation will be more severe and the challenges will be greater.
The situation we are facing is the globalization of economy and market, the intense competition, the individuation and facilitation of demand, the diversification of relevant stakeholders, and the rapid development of science and technology. This requires us to predict the future scientifically and accurately, and respond quickly. Only in this way can we maintain the advantages we have formed and catch up with the advanced.
Humanistic care and sustainable development have become the concept of scientific and technological innovation in the industry. As an extension of human capacity, construction machinery has been developing together with the progress of human civilization.With the progress of science and technology, the constant pursuit of human life quality and the importance of dignity have put forward many new topics for the development of construction machinery.China's construction machinery industry complies with the demand and attaches importance to strengtheningMicroelectronicsThe combination and integration of information technology, photoelectric technology, new material technology and mechanical manufacturing technology will promote the research and innovation of products in the fields of diversification, intelligence, and greening.
The application space of engineering machinery products has been gradually expanded with the increasing demand of human beings for quality of life, from the original traditional fields of building, road building, water conservancy, electricity, mining and other traditional fields to urban narrow construction sites, agricultural construction sites in mountainous and hilly areas and warehouses, docks, warehouses, farmhouses, gardensHorticulture, working environment of building floors and underground works, large and extra large construction projects and mine expansion.Therefore, construction machinery is required to be gradually extended to both ends, that is, miniaturization, large-scale and super large.With the continuous increase of large and extra large projects, the market demand for large and extra large construction machinery products is growing.They have the characteristics of long development and production cycle, high technology content and high added value, and represent the manufacturing level of construction machinery of a country or an important enterprise. Most of these products are monopolized by several multinational companies in developed countries.
On the other hand, in order to improve production efficiency, reduce labor intensity and improve working conditions, it has become a development trend to replace human labor with mechanical work as much as possible. In order to meet the requirements of this engineering operating environment, the demand for small and micro engineering machinery will grow rapidly.Micro products are not only subject to specific constraints on their overall dimensions, but also increasingly embody the integration with nature and environment in their appearance, shape, color and other aspects of design, and also demonstrate the humanistic care for human respect.
Secondly, the same product is developing from single function to multi-function and flexibility, that is, adding modular functional parts on the basis of general products to realize the diversification of product functions;Or through new modular design, manufacturing and flexible combination between different modules to achieve functional diversification, the traditional classification of construction machinery products will be challenged.Engineering bulldozers should extend to both ends of micro, small, large and extra large bulldozers to develop multi-functional, multi-purpose, energy-efficient products and corresponding auxiliary function modules that meet the requirements of different working conditions, such as wetlands, deserts, shrubs, etc.Loaders should develop large environmental protection products with large bucket capacity, large engine power, large digging force, large tipping load, large traction force, and low exhaust emissions, as well as multi-purpose products (such as crushers) that can be loaded, grabbed, side unloaded, lifted, and have good economy.
The engineering excavator should be extended to develop large-scalehydraulic excavator Mini excavator, unmanned hydraulic excavator, remote controlled underwater excavator, underwater bulldozer, underwater trencher.
Wheeled cranes should develop multi-functional products with advanced technology, high reliability, long service life, good construction quality and high new technology content.The informatization and intellectualization of construction machinery can improve the ability of self diagnosis and repair of various faults of construction machinery, reduce the labor intensity of construction personnel, and improve work efficiency and project quality.In some special working conditions, such as high temperature, cold, high altitude, radiation, underwater and underground conditions, it can replace the construction personnel for intelligent and high-quality construction.Operating systemAutomatic controlThe application of remote control, precise positioning and control of construction, fault diagnosis and monitoring technologies in construction machinery will become more and more common.New construction machinery products, such as loaders, excavators, road building and maintenance machinery, forklifts, concrete mixing and transportation machinery and cranes, which are developed by applying electromechanical and hydraulic integration technology, electronic computer technology, monitoring and control technology and the integration technology of these technologies, will continue to appear.[2]
