Flexible production and industrial robots
This country’s machine-building industry is now facing the task of restructing on a large scale engineering production, and developing new methods of organization, new equipment and new technologies. This is a global process. Swift production automation, the introduction of microprocessors, robotics, rotary and rotary-conveyer lines, flexible re-adjustable production is vital for today’s industry.
Industrial robots play an important part in the process. Many institutes are currently engaged in developing them. The concept of designing robot modules is making successful headway. The task today is to raise their reliability, speed and failure-free operation. Russian engineers cooperate in the development of flexible production systems with experts from different countries.
Also needed for the operation of operation of flexible systems are robots which will transport billets and parts between machine tools, i.e. transport robots, robot trailers, as well as measuring robots. Experts from the Institute of Machine Studies are developing measuring manipulators and coordinate measuring machines.
It is hard to enumerate all the problems facing our engineers and designers in the development of flexible productions. Automated systems of adjusting, controlling instruments, machined parts and many other things are needed.
The combination of flexible systems with the general system of programmed production, the spreading of flexibility to the processes of preparatory productions- foundry, forging and welding- are also very complicated problems. The flexible system must embrace all the stages of machine building, all its processes.
Гибкие производственные и промышленные роботы
В настоящее время в машиностроении этой страны стоит задача реструктуризации крупномасштабного машиностроительного производства и разработки новых методов организации, нового оборудования и новых технологий. Это глобальный процесс. Автоматизация производства Swift, внедрение микропроцессоров, робототехника, ротационные и роторно-конвейерные линии, гибкая переналадка производства являются жизненно важными для сегодняшней отрасли.
Промышленные роботы играют важную роль в этом процессе. В настоящее время многие институты занимаются их разработкой. Концепция проектирования роботизированных модулей успешно продвигается вперед. Сегодня задача состоит в повышении их надежности, скорости и безотказной работы. Российские инженеры сотрудничают в разработке гибких производственных систем с экспертами из разных стран.
Также для работы гибких систем необходимы роботы, которые будут транспортировать заготовки и детали между станками, то есть транспортные роботы, прицепы-роботы, а также измерительные роботы. Специалисты из Института машинных исследований разрабатывают измерительные манипуляторы и координатно-измерительные машины.
Трудно перечислить все проблемы, с которыми сталкиваются наши инженеры и дизайнеры при разработке гибких производств. Необходимы автоматизированные системы наладки, управления инструментами, обрабатываемые детали и многое другое.
Сочетание гибких систем с общей системой запрограммированного производства, распространение гибкости в процессах подготовки производства - литейное производство, ковка и сварка - также являются очень сложными проблемами. Гибкая система должна охватывать все этапы машинного строительства, все его процессы.
We now use the term automation for specific techniques combined to operate automatically in a complete system. These techniques are possible because of electronic devices, most of which have come into use in the last thirty years. They include program, action, sensing or feedback, decision, and control elements as components of a complete system.
The program elements determine what the system does and the step-by-step manner in which it works to produce the desired result. A program is a step-by-step sequence that breaks a task into its individual parts. The action elements are those which do the actual work. They may carry or convey materials to specific places at specific times or they may perform operations on the materials. The term mechanical handling device is also used for the action elements.
Perhaps the most important part of an automated system is sensing or feedback. Sensing devices automatically check on parts of the manufacturing process such as the thickness of a sheet of steel or paper. This is called feedback because the instruments return or feed back this information to the central system control.
The decision element is used to compare what is going on in the system with what should be going on, it receives information from the sensing devices and makes decisions necessary to maintain the system correctly. The control element consists of devices to carry out the commands of the decision element. There may be many kinds of devices: valves that open or close, switches that control the flow of electricity, or regulators that change the voltage in various machines; they make the necessary corrections or adjustments to keep the system in conformity with its program.
An industrial engineer working with automated systems is part of a team. Many components of the system, such as computers, are electronic devices so electronic devices so electronic engineers and technicians are also involved. Many of the industries in which automation has proved particularly suitable – chemicals, papermaking, metals processing – involve chemical processes, so there may be chemical engineers at work too. An industrial engineer with expertise in all these fields may become a systems engineer for automation projects thereby coordinating the activities of all the members of the team.
Machining is only one part of the overall production process in the engineering workshop. There are two more basic operations: design and administration. In the engineering industry of the future, all three of these operations will be done with the help of computers, which will greatly reduce the need for labor.
There would be three main computers: one each for the flexible manufacturing system, design and administration. Instructions that enter the first computer control how and which goods are made; draughtsman work out which goods they want made with the second machine; and in the third are lodged all the details about orders, scheduling, the state of stocks and so on. All three computers are linked to each other, and also to an automated warehouse from which raw materials are passed by a transport mechanism to the factory floor and the machining area.
The few places where people would be involved with the factory's processes would be in the design room and in a control area where the factory's administrators sit. Draftsmen would design products using their keyboards and screens. The codes representing these parts would come along wires to the production computer, which, in turn, would instruct its battery of machine tools to make the items. There would be a few "seeing" robots in the production department, to make the assembly job easier. Meanwhile, the factory's administrators could keep track of the whole operation, getting information from the system by keying in instructions to their terminals.
At the heart of the factory would be a complex communications network that links all the machines in the plant so that they constantly relay instructions to each other. In this way all the machines in the plant would inform each other of what is going on. The mechanisms in the plants will be linked by wires in the same way as the telephone network connects up towns and villages, houses and offices. The main difference is that the machines will talk to each other in a binary code.
It would not be an unmanned factory, but it would be pretty near such a thing. Given the rate of technical progress over the past ten to twenty years, such plants will be with us very soon.
Heating and ventilation
Besides masonry, a brick work, any engineer must know about heating and ventilation. They are two branches of engineering which are very closely connected. Both they are treated as a dual subject. Heating is to prevent too rapid loss of heat from the body. The rate of heat lost from the body is controlled. Some old concepts of heating have been gradually changed since engineers obtained more precise knowledge about how the body loses heat. Insufficient attention was paid formerly to loss by radiation, which is the transmission of energy in the form of waves from a body to surrounding bodies at a temperature. The human being also loses heat by conduction and convection, the latter by air currents not only past his skin or outside clothing surface but also by evaporation of moisture from his skin.
The determination of the capacity or size of the various components of the heating system is based on the fundamental concept that heat supplied to a space equals heat lost from the space. The most widely used system of heating is the central heating. There are two most common systems of heating: hot water and steam. There the fuel is burned in one place, from which steam, hot water or warm air is distributed to adjacent and remote spaces to be heated. Both systems are widely used nowadays. A hot-water system consists of the boilers and a system of pipes connected to radiators suitably located in the rooms. The steel or copper pipes give hot water to radiators or convectors which give up their heat to the rooms. Then cooled water is returned to the boiler for reheating. As for steam systems, steam is usually generated. The steam is led to the radiators through or by means of steel or copper pipes. The steam gives up its heat to the radiators and the radiators to the room. The condensate is returned to the boiler by gravity or by a pump. The air valve on each radiator is necessary for air to escape. Otherwise it would prevent steam from entering the radiator.
Recent efforts have resulted to completely conceal heating equipment in an arrangement. Hot water, steam, air, or electricity are circulated through distribution units embedded in the building construction. Panel heating is a method of introducing heat to rooms in which emitting surfaces are usually completely concealed in the floor, walls or ceiling. The heat is disseminated from such panels partly by radiation and partly by convection. Ceiling panels release the largest proportion of heat by radiation and floor panels release the smallest one. The proportion of heat disseminated by radiation and convection is also dependent to some extent upon panel-surface temperatures.
Nowadays a building's framework is made of reinforced concrete and of structural steel. Concrete is made by mixing together small stones, sand, cement and water. The coarse stones used in the mix give the concrete its strength. The sand is needed to fill the gaps between the stones. The cement, mixed with just enough water to make it into a paste, covers the surface of all solids, and binds the entire mixture into single mass. It is used less water to make mixing concrete denser and stronger. It is a difficulty here. Dry mixing concrete is not so easy to stir as one that is fairly wet and sloppy. When it is really strong concrete, it is mixed with the necessary minimum of water and placed in the forms.
After this it is vibrated with electrically vibrated bars. The mixture is tipped or piped into forms (wooden molds) of the shape required. To make concrete resistant to bending, building engineers reinforce it. It is done by putting bars of steel or miniature steel frameworks into the forms. Hence is named «reinforced concrete». With such a material a variety of constructional shapes can be produced. They can be "shells" and roofs. For this reinforced concrete is used in thin sheets. Reinforced concrete can be used more effectively if before the external load comes on. For instance, suppose that a reinforced beam could be bent out of the straight by an inch before it developed serious cracks. By pressing it in reverse, building engineers prepare the concrete in advance to withstand the pressures and pulls that the external load causes. Concrete can be pressed in two ways. In the first method, the concrete is casted around stretched steel wires. After setting concrete, the wires are released and compress the concrete as they contract. Such a method of pressing produces pretension concrete.
The other method is called post-tensioning. In the case of a beam the concrete is casted around polythene tubes. After setting concrete- steel cables are drawn through polythene tubes. These cables are anchored at one end of the beam, stretched by jacks and then fixed at the end of the beam. In constructing of a building, it is possible to cast the floors and walls as well as the framework directly on the spot where they are to stand. Building forms a monolith. Last one is a large artificial stone composed entirely of concrete that has been shaped within wooden molds fitted together perfectly. To cast all the parts in place, a builder has to use many forms. They are removed as soon as the concrete has set. Before beginning another work, concrete must be given plenty of time to harden. In order to save time, a builder may prefer to use a number of standardized concrete units. These can be made. Individual members can be pressed. Also different sections of the building can be prefabricated.
Central heating system
The term "central heating" applied to the heating of domestic and other buildings indicates that the whole of a building is heated from a central source. Usually an independent boiler is fired by solid fuel, gas, electricity or fuel oil.
The boiler is generally placed at the lowest available point in the building, having regard at the same time to convenience of stoking and delivery of fuel. The boiler may be one of a number of types. It may be a solid one-piece casting, rectangular in form; it may be sectional; or it may be conical in shape and wrought or cast iron. For smaller system, the first and last-named types are both cheap and suitable. The sectional boiler has the advantage of the possibility of added sections should more heat be needed subsequent to initial installation.
Sectional and shell type boilers are almost invariably used for bigger installations.
In general, a heating system should be designed so that the water will circulate by gravity. In some installations, circumstances are such that a pump or accelerator must be used to achieve a satisfactory circulation. This should be avoided if possible.
When designing a heating system for a large building, it is usual — in the interests of economy and to ensure efficient heating — to first calculate how much heat will be needed to maintain the building at the desired temperature. Then the size of the boiler and the amount of pipe and radiator heating surface required to give out this heat will be estimated. For small systems, "rule-of-thumb" methods and past experience are generally a sufficient guide.
The overhead drop-feed system shows how the hot water from the boiler is carried as high as possible in the building, from where it falls "in cooling, through the various branch pipes and radiators, back to the boiler. In this type of system, the maximum amount of "circulating head" or pressure, would be obtained.
Building materials are very important in the construction. But it is more important for any designer to select and adapt such building materials of construction that will give the most effective result by the most economical means. In this choice of materials for any work of constructions many factors must be considered by the civil engineer. These factors include availability, cost, physical properties of materials and others.
Practically, all buildings materials have their advantages and disadvantages. That’s why some materials are used most widely in building construction for the purpose of binding together masonry units. Among them are lime, gypsum and cement. Last material forms very important elements in all masonry structures, such as stone, a brick. Since the time of its introduction a gradual improvement of Portland cement quality has led to the elaboration of rapid hardening Portland cements, or “high early strength”. Portland cement like other materials can be modified to suit a particular application. Later developments include low heat and sulphate-resisting cements. The scope for such purpose – made cements has led to the development of an increasing variety such as high alumina cement, blast-furnace slag. They may be also white and colored cements. Alumina cement has an extremely high rate of strength increase. Portland blast- furnace cement has greater resistance to some forms of chemicals.
So, cement is the most important component of concrete. Concrete is even less uniform than many other materials. Concrete may be considered an artificial conglomerate of “crushed stone, gravel or similar inert material with a mortar”. A mortar is a mixture of sand, screenings or similar inert particles with cement and water. It is very important to know everything about proportions. The most accurate method of measuring proportions is to weigh the required quantities of each material. This may be done whether the proportions are based upon volumes or weights. This method is being extensively used in road construction and in many central mixing and in central proportioning plants. It is also widely used in large building constructions. Sometimes timber, steel and concrete are all very over considerable ranges in the properties desired by the engineer. Even steel varies considerably in its microstructure.
The Role of Science in Manufacture
Future improvements in productivity are largely dependent on the application of science to manufacturing. This depends in turn on the availability of large numbers of scientifically trained engineers. Higher schools can serve the needs of industry in two ways: by performing basic research and by training well-qualified engineers in the manufacturing field.
There is a growing need for engineers who are familiar with the fundamental problems in metal processing and manufacturing. In the near future many of the engineers will be recent university graduates. A few will come through courses of study in industry. Others, having a basic engineering knowledge will continue additional studies at colleges to prepare themselves for work in industry. Therefore, an engineer does not finish his education when he receives his diploma, particularly in the fields of interest to tool engineers who are to study new developments constantly.
There are numerous ways in which industry and education can cooperate on problems of common interest. Scientists and research engineers are engaged in work that is intended to provide a scientific approach to many purely industrial problems. These scientists and engineers can make a real contribution to engineering education or academic research. They can, for example, teach advanced engineering courses and they can actively participate in basic and applied research.
Similarly, large and complicated projects of new technologies could well be handled by institute researchers working on practical applications. This would often provide the most efficient approach to the solution of processing problems.
Chemical and physical changes
An iron rod held in the fire long enough increases in energy content until it u becomes too hot to hold in the unprotected hand. Nevertheless the rod is still iron, and when cooled to its originals temperature,1 its properties are just as they were before. The heating and subsequent cooling of the rod are examples of physical changes. A physical change may result in a more or less temporary alteration of a few of the properties of a substance involved, but no change of composition results from it and most of the altered properties usually regain their former value. Changes of this type are numerous and many of them are familiar to everyone. As an example we may take the behavior of ice when it is heated. At first when heated the ice melts, when further heated, the liquid water boils forming the gaseous water. If the steam is cooled, the process is reversed - when cooled sufficiently, the ice results.
The substance present in every instance was water. This experiment shows that there are three physical states in which the substance may exist. If the rod concerned is placed in a container of hydrochloric acid, it will be noted that bubbles begin to on the road. If the rod involved is left in the acid for some time, the evolution of gas will continue. When examined, it will be found that the rod has diminished in mass or disappeared altogether. The liquid in the container if examined will have a greenish color. If evaporated, a mass of greenish crystals will be obtained. The crystals will have totally different properties. This is an example of a chemical change.
So, a change may be called a chemical reaction or simply a reaction, the substances entering into a chemical reaction are called reactants. Phenomena accompanied by radical changes of substances are called chemical phenomena.
Cutting is one of the oldest arts practiced in the stone age , but the cutting of metals was not found possible until the 18th century, and its detailed study started about a hundred years ago.
Now in every machine-shop you may find many machines for working metal parts, these cutting machines are generally called machine-tools and are extensively used in many branches of engineering. Fundamentally all machine-tools remove metal and can be divided into the following categories:
1. Turning machines (lathes)
2. Drilling machines
3. Boring machines
4. Milling machines
5. Grinding machines
Machining of large-volume production parts is best accomplished by screw machines. These machines can do turning, threading, facing, boring and many other operations. Machining can produce symmetrical shapes with smooth surfaces and dimensional accuracies not generally attainable by most fabrication methods.
Screw-machined parts are made from bar stock or tubing fed intermittently and automatically through rapidly rotating hollow spindles. The cutting tools are held on turrets and tool slides convenient to the cutting locations. Operations are controlled by cams or linkages that position the work, feed the tools, hold them in position for the proper time, and then retract the tools. Finished pieces are automatically separated from the raw stock and dropped into a container.
Bushings, bearings, nuts, bolts, studs, shafts and many other simple and complex shapes are among the thousands of products produced on screw machines. Screw machining is also used to finish shapes produced by other forming and shaping processes.
The oldest domestic bricks were found in Greece. In the 12th century, bricks from Northern-Western Italy were re-introduced to Northern Germany, where an independent tradition evolved. It culminated in the so-called brick Gothic, a reduced style of Gothic architecture that flourished in Northern Europe, especially in the regions around the Baltic Sea, which are without natural rock resources. Brick Gothic buildings, which are built almost exclusively of bricks, are to be found in Denmark, Germany, Poland, and Russia. During the Renaissance and the Baroque, visible brick walls were unpopular and the brickwork was often covered with plaster. It was only during the mid-18th century that visible brick walls regained some degree of popularity. The transport in bulk of building materials such as bricks over long distances was rare before the age of canals, railways, roads and heavy goods vehicles. Before this time bricks were generally made close to their point of intended use. It has been estimated that in England in the 18th century carrying bricks by horse and cart for ten miles (approx. 16 km) over the poor roads then existing could more than double their price.
Bricks were often used for reasons of speed and economy, even in areas where stone was available. The buildings of the Industrial Revolution in Britain were largely constructed of brick and timber due to the demand created. During the building boom of the 19th century in the eastern seaboard cities of Boston and New York City, for example, locally made bricks were often used in construction in preference to the brownstones of New Jersey and Connecticut for these reasons.
The trend of building high office buildings that emerged towards the beginning of the 20th century displaced brick in favor of cast and wrought iron and later steel and concrete. Some early 'skyscrapers' were made in masonry, and demonstrated the limitations of the material – for example, the Monadnock Building in Chicago is masonry and just 17 stories high; the ground walls are almost 6 feet (1.8 m) thick to give the needed support; clearly building any higher would lead to excessive loss of internal floor space on the lower floors.
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