Пояснительная записка Данная рабочая тетрадь предназначена для студентов средних специальных учебных заведений по специальности 230401 Информационные системы (по отраслям)
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ТЕМА 3.4. ДЕТАЛИ И МЕХАНИЗМЫ. Практическое занятие № 12 Machine – Tools Machine-tools are used to shape metals and other materials. The material to be shaped is called the workpiece. Most machine-tools are now electrically driven. Machine-tools with electrical drive are faster and more accurate than hand tools: they were an important element in the development of mass-production processes, as they allowed individual parts to be made in large numbers so as to be interchangeable. All machine-tools have facilities for holding both the workpiece and the tool, and for accurately controlling the movement of the cutting tool relatively to the workpiece. Most machining operations generate large amounts of heat, and cooling fluids (usually a mixture of water and oils) must be used for cooling and lubrication. Machine-tools usually work materials mechanically but other machining methods have been developed lately. They include chemical machining, spark erosion to machine very hard materials to any shape by means of a continuous high-voltage spark (discharge) between an electrode and a workpiece. Other machining methods include drilling using ultrasound, and cutting by means of a laser beam. Numerical control of machine-tools and flexible manufacturing systems have made it possible for complete systems of machine-tools to be used flexibly for the manufacture of a range of products. New words: machine-tools – станки electrically driven – с электроприводом fluid – жидкость spark erosion – электроискровая обработка by means of – посредством drilling – сверление Найдите в правой колонке перевод английских слов:
____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Give a short summary of the text. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Практическое занятие № 13 Robots in Industry Today most robots are used in manufacturing operations. The applications of robots can be divided into three categories:
Material handling is the transfer of material and loading and unloading of machines. Material - transfer applications require the robot to move materials or work parts from one to another. Many of these tasks are relatively simple: robots pick up parts from one conveyor and place them on another. Other transfer operations are more complex, such as placing parts in an arrangement that can be calculated by the robot. The processing operations robot manipulates a tool to perform a process on the work part. Examples of such applications include spot welding, continuous arc welding and spray painting. Spot welding of automobile bodies is one of the most common applications of industrial robots. The robot positions a spot welder against the automobile panels and frames to join them. Arc welding is a continuous process in which robot moves the welding rod along the welding seam. Spray painting is the manipulation of a spray-painting gun over the surface of the object to be coated. The third application area of industrial robots is assembly and inspection. The use of robots in assembly is expected to increase because of the high cost of manual labour. But the design of the product is an important aspect of robotic assembly. Inspection is another area of factory operations in which the utilization of robots is growing. It is a typical inspection job. There are certain characteristics of industrial jobs performed by humans that can be done by robots:
New words: transfer – передача, перенос location – местонахождение arrangement – расположение to utilize – утилизировать, находить применение frame – рама spot welding – точечная сварка continuous – непрерывный spray painting – окраска распылением spray-painting gun – распылитель краски manual – ручной labour – труд shift – смена Answer the questions:
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Практическое занятие № 14 Machines and Work Defined in the simplest terms a machine is a device that uses force to accomplish something. More technically, it is s device that transmits and changes force or motion to work. This definition implies that a machine must have moving parts. A machine can be very simple, like a block and tackle to raise a heavy weight, or very complex, like a railroad locomotive or the mechanical systems used for industrial processes. A machine receives input from an energy source and transforms it into output in the form of mechanical or electrical energy. Machines whose input is a natural source of energy are called prime movers. Natural sources of energy include wind, water, steam, and petroleum. Windmills and waterwheels are prime movers; so are the great turbines driven by water or steam that turn the generators that produce electricity. Electric motors are not prime movers, since an alternating current of electricity which supplies most electrical energy does not exist in nature. Terms like work, force, and power are frequently used in mechanical engineering, so it is necessary to define them precisely. Force is an effort that results in motion or physical change. If you use your muscles to lift a box you are exerting force on that box. The water which strikes the blades of a turbine is exerting force on those blades, thereby setting them in motion. In a technical sense work is the combination of the force and the distance through which it is exerted. To produce work, a force must act through a distance. If you stand and hold a twenty-pound weight for any length of time, you may get very tired, but you are not doing work in an engineering sense because the force you exerted to hold up the weight was not acting through a distance. However, if you raised the weight, you would be doing work. Power is another term used in a special technical sense in speaking of machines. It is the rate at which work is performed. The rate of doing work is sometimes given in terms of horsepower, often abbreviated hp. This expression resulted from the desire of the inventor James Watt to describe the work his steam engines performed in terms that his customers could easily understand. After much experimentation, he settled on a rate of 33,000 foot-pounds per minute as one horsepower. In the metric system power is measured in terms of watts and kilowatts. The kilowatt, a more widely used term, equals a thousand watts or approximately 1,1/3 horsepower in the English system. Соедините термин с соответствующим ему определением.
______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Заполните следующую таблицу.
Как следует из содержания текста, все абзацы включают в себя определение какого-нибудь понятия, разъяснение этого понятия, пример. Например, первый абзац можно представить в виде следующей схемы: 1 абзац
Постройте структурную схему каждого абзаца. 2 абзац
Вводное предложение Определение понятия «_____" 3 абзац Определение понятия 4 абзац Сделайте краткое сообщение на тему “Machine, Work, Power”. При подготовке используйте активный словарь.
___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Практическое занятие № 15 Melting Furnaces The metals used in various kinds of castings are melted in several types of furnaces. They are cupolas, electric furnaces, open-hearth furnaces, crucible furnaces and some others. A cupola furnace is a vertical type, cylindrical or shaft furnace designed to melt ferrous metals in the production of cast iron castings. The cupola consists of a refractory-lined steel stack testing on a cast iron base plate which is supported by four steel legs. The bottom of the cupola consists of two doors which are supported in closed position by a centre prop. Iron, coke and flux are charged onto a coke bed and are held above the tuyere openings where the maximum temperature is maintained. Molten metal is tapped through a tap hole at the base of the cupola. Although the first cupola was built about 1720 cupola melting is still recognized as the most economical melting process and most of the grey cast iron produced is melted by this method. Electric furnaces are used for producing high quality castings. The principle of the electric furnace operation is based on the heating effect obtainable from the passing of electricity. There are three general types: arc, induction and resistance. Arc furnaces are used for melting or refining ferrous metals. Two types of arc furnaces are in use: direct-arc and indirect-arc. In the direct-arc furnace the arc comes in direct contact with the metal charge. Indirect-arc furnaces are the type in which the arc is maintained between two electrodes above the charge. In the induction furnace electric current are induced in the charge and their circulation through the charge produces heat. This type of furnace is used for producing exact alloys. In the resistance furnace the electrodes are placed in the charge and the flow of electric current through the charge produces heat. These furnaces are generally used for non-ferrous metals production. New words: cupola – вагранка refractory-lined stack –шахта, облицованная огнеупорным материалом to rest – опираться prop – подпорка tuyere opening – фурменное отверстие (для подачи в печь воздуха) to maintain – поддерживать to tap metal – выпускать металл arc furnace – электродуговая печь direct-arc furnace – электродуговая печь прямого нагрева indirect-arc furnace – электродуговая печь непрямого нагрева resistance furnace – печь сопротивления metal charge – металлическая шихта Скажите, какие из данных утверждений соответствуют содержанию текста. 1. The cupola is designed to melt non-ferrous metals. 2. Cupola melting is the most economical melting process. 3. The cupola is a horizontal type furnace. 4. Iron, coke and flux are charged onto a coke bed at the bottom of the furnace. 5. The maximum temperature is maintained under the tuyere openings. 6. Molten metal is tapped through a tap hole. Завершите предложения, выбрав соответствующие окончания в правом столбце.
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