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Архитектура Аудит Военная наука Иностранные языки Медицина Металлургия Метрология Образование Политология Производство Психология Стандартизация Технологии |
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Архитектура Аудит Военная наука Иностранные языки Медицина Металлургия Метрология Образование Политология Производство Психология Стандартизация Технологии |
Materials Science and TechnologyСтр 1 из 10Следующая ⇒
THEME 1 Materials Science and Technology Vocabulary: to fabricate – изготовлять, производить ( to ) need – нуждаться, потребность way – путь, способ, образ (действия) to respond – отвечать, отзываться, реагировать external – внешний, наружный force – сила, усилие elastic – упругий, эластичный permanent – постоянный volume – объем, емкость ( to ) cause – вызывать, причина to subject – подвергать to decrease – исчезать to increase – увеличивать to remain – оставаться to exceed – превышать to eliminate – устранять, ликвидировать Text 1. Translate into English the following sentences:
Text 2. PROPERTIES OF MATERIALS Density (specific weight) is the amount of mass in a unit volume. It is measured in kilograms in per cubic meter. The density of water is 1000 kg/m3 but most materials have a higher density and sink in water. Aluminum alloys, with typical densities around 2800 kg/m3 are considerably less dense than steels, which have typical densities around 7800 kg/m3. Density is important in any application where the material must not be heavy. Stiffness (rigidity) is a measure of the resistance to deformation such as stretching or bending. The Young modulus is a measure of the resistance to simple stretching or compression. It is the ratio of the applied force per unit area (stress) to the fractional elastic deformation (strain). Stiffness is important when a rigid structure is to be made. Strength is the force per unit area (stress) that a material can support without failing. The units are the same as those of stiffness, MN/m2, but in this case the deformation is irreversible. The yield strength is the stress at which a material first deforms plastically. For a metal the yield strength may be less than the fracture strength, which is the stress at which it breaks. Many materials have a higher strength in compression then in tension. Ductility is the ability of material to deform without breaking. One of the great advantages of metals is their ability to be formed into the shape that is needed, such as car body parts. Materials that are not ductile are brittle. Ductile materials can absorb energy by deformation but brittle materials cannot. Toughness is the resistance of a material to breaking when there is a crack in it. For a material of given toughness, the stress at which it will fail is inversely proportional to the square root of the size of the largest defect present. Toughness is different from strength: the toughest steels, for example, are different from the ones with highest tensile strength. Brittle materials have low toughness: glass can be broken along a chosen line by first scratching it with a diamond. Composites can be designed to have considerably greater toughness than their constituent materials. The example of a very tough composite is fiberglass that is very flexible and strong. Creep resistance is the resistance to a gradual permanent change of shape, and it becomes especially important at higher temperatures. A successful research has been made in materials for machine parts operate at high temperatures and under high tensile forces without gradually extending, for example the parts of plane engines.
Additional vocabulary: ability – способность absorb – поглощать amount – количество application – применение brittle – хрупкий, ломкий car body – кузов автомобиля constituent – компонент crack – трещина creep resistance – устойчивость к ползучести definition – определение density – плотность ductility – ковкость, эластичность failure – повреждение, разрушение gradual – постепенный rigid – жесткий to sink – тонуть square root – квадратный корень stiffness – жесткость strain – нагрузка, напряжение, деформация strength – прочность stress – давление, напряжение tensile strength – прочность на разрыв toughness – прочность, стойкость yield strength – предел текучести Young modulus – модель Юнга
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Text 3. COMPOSITE MATERIALS The combination of two or more different materials are called composite materials. They usually have unique mechanical and physical properties because they combine the best properties of different materials. For example, a fibre-glass reinforced plastic combines the high strength of thin glass fibres with the ductility and chemical resistance of plastic. Nowadays composites are being used for structures such as bridges, boat-building etc. Composite materials usually consist of synthetic fibres within a matrix, a material that surrounds and is tightly bound to the fibres. The most widely used type of composite materials is polymer matrix composites (PMCs). PMCs consist of fibres made of a ceramic material such as carbon or glass embedded in a plastic matrix. Usually the fibres make up about 60 per cent by volume. Composites with metal matrices or ceramic matrices are called metal matrix composites (MMCs) and ceramic matrix composites (CMCs), respectively. Continuous-fibre composites are generally required for structural applications. The specific strength (strength-to-density ratio) and specific stiffness (elastic modulus-to-density ratio) of continuous carbon fibre PMCs, for example, can be better than metal alloys have. Composites can also have other attractive properties, such as high thermal or electrical conductivity and a low coefficient of thermal expansion. Although composite materials have certain advantages over conventional materials, composites also have some disadvantages. For example, PMCs and other composite materials tend to be highly anisotropic-that is, their strength, stiffness and other engineering properties are different depending on the orientation of the composite material. For example, if a PMC is fabricated so that all the fibres are lined up parallel to one another, then the PMC will be very stiff in the direction parallel to the fibres, but not stiff in the perpendicular direction. The designer, who uses composite materials in structures subjected to multidirectional forces, must take these anisotropic properties into account. Also, forming strong connections between separate composite material components is difficult. The advanced composites have high manufacturing costs. Fabricating composite materials is a complex process. However, new manufacturing techniques are developed. It will become possible to produce composite materials at higher volumes and at a lower cost than is now possible, accelerating the wider exploitation of these materials. Additional vocabulary: fiberglass – стеклопластик, фибергласс fibre – волокно, нить reinforced – упроченный expansion – расширение matrix – матрица ceramic – керамический specific strength – удельная прочность specific stiffness – удельная жесткость anisotropic – анизотропный
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Text 4. Ferrous metals and steels. 1. Ferrous metals consist of iron combined with carbon, silicon and other elements. But carbon is the most important element in ferrous alloys. 2. Ferrous metals are used in industry in two forms: steel and cast iron, which differ in the quantity of carbon content. 3. Alloys consist of a simple metal combined with some other element. Steel is a ferrous material having some carbon content. There are two kids of steel: carbon steel and alloy steels. 4. Carbon steel should contain only iron and carbon without any other alloying element. 5. Alloy steels are those in which in addition to carbon an alloying element is present. These alloying elements have an effect on the properties of steel. They increase its strength and hardness, for example, high percentage of chromium makes steel rust-resistant, and we call it “stainless steel”. 6. Strengthm, ductility and machinability are the most important industrial and commercial properties of steel. Such properties as resistance to wear, electrical conductivity, magnetic properties are important in special uses of metals. 7. According to their chemical and mechanical properties steel may be used in different branches of industry, for example, in machinebuilding, rocket engineering, automobile industry, ets. Answer the questions:
Text 5. Metals and nonmetals. 1. There are some distinctions between metals and nonmetals. Metals are distinguished from nonmetals by their high conductivity for heat and electricity, by metallic luster and by their resistance to electric current. Their use in industry is explained not only by those properties, but also by the fact that their properties, such as strength and hardness, can be greatly improved by alloying them with other metals. 2. There are several important groups of metals and alloys. The common metals such as iron, copper, zinc, etc are produced in great quantities. 3. The so-called precious metals include silver, gold, platinum and palladium. The light metals are aluminium, beryllium and titanium. They are important in aircraft and rocket construction. 4. Many elements are classified as semimetals (bismuth, for example) because they have much poorer conductivity than common metals. 5. Nonmetals (carbon, silicon, sulphur) in the solid state are usually brittie materials without metallic lustre and are usually poor conductors of electricity. Nonmetals show greater variety of chemical properties than common metals do. 6. Metals can undergo corrosion, changing in this case their chemical and electromechanical properties. In order to protect metals from corrosion the products made of metals and steel are coated by some films (coatings). Organic coatings protect metals and steel from corrosion by forming a corrosion-resistant barrier between metal or steel and the corrosive environment. Answer the questions:
THEME 2 Metals and Metalworking. Vocabulary: separation – разделение, интервал, расстояние failure – повреждение, разрушение, отказ malleable – ковкий, податливый, способный деформироваться to bend (bent, bent) – сгибать(ся), гнуть(ся), изгибать(ся) dense – плотный ( to ) fracture – ломать(ся), разрушение, излом, перелом dictile – эластичный, ковкий, пластичный grain – зерно to depend – зависеть shape – форма, формировать size – размер, величина treatment – обработка stress – давление, напряжение alloy – сплав brittle – хрупкий, ломкий to apply – применять useful – полезный edge – кромка, край, лезвие to avoid – избегать, уклоняться to undergo – подвергаться flaw – недостаток, дефект Text 1 . METALS Metal are materials most widely used in industry because of their properties. The study of the production and properties of metals is known as metallurgy. The separation between the atoms in metals is small, so most metals are dense. The atoms are arranged regularly and can slide over each other. That is why metals are malleable (can be deformed and bent without fracture) and ductile (can be drawn into wire). Metals very greatly in their properties. For example, lead is soft and can be bent by hand, while iron can only be worked by hammering at red heat.
The regular arrangement of atoms in metals gives them a crystalline structure. Irregular crystals are called grains. The properties of the metals depend on the size, shape, orientation, and composition of these drains. In general, a metal with small grains will be harder and stronger than one with coarse grains. Heat treatment controls the nature of the grains and their size in the metal. Small amounts of other metals (less than 1 per cent) are often added to a pure metal. This is called alloying (легирование) and it changes the grain structure and properties of metals. All metals can be formed by drawing, rolling, hammering and extrusion, but some require hot-working. Metals are subject to metal fatigue and to creep (the slow increase in length under stress) causing deformation and failure. Both effects are taken into account by engineers when designing, for example, airplanes, gas-turbines, and pressure vessels for high-temperature chemical processes. Metals can be worked using machine-tools. The ways of working a metal depend on its properties. Many metals can be melted and cast in moulds, but special conditions are required for metals that react with air.
Additional vocabulary: metallurgy – металлургия arrangement – расположение regularly – регулярно, правильно coarse – грубый, крупный to draw – волочить, тянуть wire – проволока lead – свинец iron – железо, чугун composition – волочить to hammer – ковать (напр. молотом) extrusion – экструзия rolling – прокатка metal fatigue – усталость металла creep – ползучесть to slide – скользить vessel – сосуд, котел, судно to cast – отливать, отлить mould – форма (для отливки)
Questions: 1. What are metals and that do we call metallurgy? 2. Why are most metals dense? 3. Why are metals malleable? 4. What is malleability? 5. What are grains? 6. What is alloying? 7. What is crystalline structure? 8. What to the properties of metals depend on? 9. What changes the size of grains in metals? 10. What are the main processes of metal forming? 11. How are metals worked? 12. What is creeping?
Complete the following sentences: 1. Metals are… 2. Metallurgy is… 3. Most metals are… 4. The regular arrangement of atoms in metals… 5. Irregular crystals… 6. The properties of the metals depend… 7. Metals with small grains will be… 8. …controls the nature of the grains in the metal. 9. Alloying is… 10. All metals can be formed by… 11. Creep is… 12. Metals can be worked using…
Translate into English: 1. Металлы – плотные материалы потому, что между атомами в металлах малое расстояние. 2. Металлы имеют кристаллическую структуру из-за правильного расположения атомов. 3. Чем меньше зерна, тем тверже металл. 4. Легирование изменяет структуру зерен и свойства металлов. 5. Металл деформируется и разрушается из-за усталости и ползучести. Text 2 . STEEL The most important metal in industry is iron and its alloy – steel. Steel is an alloy of iron and carbon. It is strong but corrodes easily through rusting, although stainless and other special steels resist corrosion. The amount of carbon in steel influences its properties considerably. Steels of low carbon content (mild steels) are quite ductile and are used in the manufacture of sheet iron, wire and pipes. Medium-carbon steels containing from 0.2 to 0.4 per cent carbon are tougher and stronger and are used as structural steels. Both mild and medium-carbon steels are suitable for forging and welding. High-carbon steels contain from 0.4 to 1.5 per cant carbon, are hard and brittle and are used in cutting tools, also called silver steel, contains about 1 per cant carbon and is strengthened and toughened by quenching and tempering. The inclusion of other elements affects the properties of the steel. Manganese gives extra strength and toughness. Steel containing 4 per cent silicon is used for transformer cores or electromagnets because it has large grains acting like small magnets. The addition of chromium gives extra strength and corrosion resistance, so we can get rust-proof steels. Heating in the presence of carbon or nitrogen-rich materials is used to from a hard surface on steel (case-hardening). High-speed steels, which are extremely important in machine-tools, contain chromium and tungsten plus smaller amounts of vanadium, molybdenum and other metals. Additional vocabulary: carbon – углерод to corrode – разъедать, ржаветь rusting – ржавление stainless – нержавеющий to resist – сопротивляться considerably – значительно, гораздо tough – крепкий, жесткий, прочный, вынословый forging – ковка welding – сварка cutting tools – режущие инструменты core – сердечник surgical instruments – хирургические инструменты blade – лезвие spring – пружина inclusion – включение to affect – влиять marganese – марганец silicon – кремний post-proof – нержавеющий case-hardening – упрочнение цементацией
nitrogen – азот tungsten – вольфрам
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Text 3. Text 4. HOT WORKING OF STEEL An important feature of hot working is that it provides the improvement of mechanical properties of metals. Hot-working (hot-rolling or hot-forging) eliminates porosity, directionality, and segregation that are usually present in metals. Hot-worked products have better ductility and toughness than the unworked casting. During the forging of a bar, the grains of the metal become greatly elongated in the direction of flow. As a result, the toughness if the metal is greatly improved in this direction and weakened in directions transverse to the flow. Good forging makes the flow lines in the finished part oriented so as to lie in the direction of maximum stress when the part is placed in service. The ability of a metal to resist thinning and facture during cold-working operations plays an important role in alloy selection. In operations that involve stretching, the best alloys are those which grow stronger with strain (are strain hardening) – for example, the copper-zinc alloy, brass, used for cartridges and the aluminum-magnesium alloys in beverage cans, which exhibit greater strain hardening. Fracture of the workpiece during forming cal result from inner flaws in the metal. These flaws often consist of nonmetallic inclusions such as oxides or sulfides that are trapped in the metal during refining. Such inclusions can be avoided by proper manufacturing procedures. The ability of different metals to undergo strain varies. The change of the shape after one forming operation is often limited by the tensile ductility of the metal. Metals such as copper and aluminum are more ductile in such operations than other metals.
Additional vocabulary: feature – черта, особенность to provide – обеспечивать improvement – улучшение porosity – пористость directional – направленный to segregate – разделять casting – отливка elongated – удлиненный to weaken – ослабевать, ослаблять transverse – поперечный flow – течение, поток finished – отделанный thinning – утончение strain hardening – деформационное упрочнение brass – латунь beverage – напиток can – консервная банка to exhibit – проявлять inner – внутренний inclusion – включение trapped – заключенный refining – очищать, очистка tensile ductility – пластичность при растяжении Questions:
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Translate into English: 1. Горячая обработка металла улучшает его механические свойства и устраняет пористость и внутренние дефекты. 2. Удлинение зерен в направлении текучести при ковке значительно улучшает прочность металла в этом направлении и уменьшает его прочность в поперечном. 3. Хорошая проковка ориентирует линии текучести в направлении максимального напряжения. 4. Деформационное упрочнение металла при холодной обработке очень важно для получения металлов с улучшенными свойствами. 5. Внутренние дефекты металла – это неметаллические включения типа оксидов или сульфидов. 6. Изменение формы при штамповании металлических деталей ограничивается пластичностью металла при растяжении. THEME 3 Basic Engineering Processes Vocabulary: to subject – подвергать condition – состояние, условие initial – начальный, первоначальный to determine – устанавливать, определять reduction – сокращение to achieve – достигать beyond – выше, свыше to retain – сохранять, удерживать to join – соединять source – источник available – имеющийся в наличии, доступный advantage – преимущество considerably – значительно, гораздо to harden – упрочнять application – применение, использование, употребление Text 1 . METALWORKING Metals are important in industry because they can be easily deformed into useful shapes. A lot of metalworking processes have been developed for certain applications. They can be divided into five broad groups:
During the first four processes metal is subjected to large amounts of strain (deformation). Bit if deformation goes at a high temperature, the metal will recrystallize – that is, new strain-free grains will grow instead of deformed grains. For this reason metals are usually rolled, extruded, drawn, or forged above their recrystallization tempetature. This is called hot working. Under these conditions there is no limit to the compressive plastic strain to which the metal can be subjected. Other processes are performed below the recrystallization tempetature. These are called cold working. Cold working hardens metal and makes the part stronger. However, there is a limit to the strain before a cold part cracks. Rolling Rolling is the most common metalworking process. More than 90 percent of the aluminum, steel and copper produced are rolled at least once in the course of production. The most common rolled product is sheet. Rolling can be done either hot or cold. If the rolling is finished cold, the surface will be smoother and the product stronger. Extrusion
Extrusion is pushing the billet to flow through the orifice of a die. Products may have either a simple or a complex cross section. Aluminum window frames are the example of complex extrusions. Tubes or other hollow parts can also be extruded. The initial piece is a thick-walled tube, and the extruded part is shaped between a die on the outside of the tube and a mandrel held on the inside. In back-extrusion (штамповка выдавливанием) the workpiece is placed in the bottom of a hole and a loosely fitting ram is pushed against it. The ram forces the metal to flow back around it, with the gap between the ram and the die determining the wall thickness. The example of this process is the manufacturing of aluminum beer cans. Additional vocabulary: metalworking – металлообработка shape – форма, штамповать rolling – прокатка extrusion – экструзия, выдавливание drawing – волочение forging – ковка sheet – лист at least – по крайней мере common – общий billet – заготовка, болванка orifice – отверстие cross section – поперечное сечение die – штамп, пуансон, матрица, фильера, волочильная доска window frame – рама окна tube – труба initial piece – заготовка hollow – полный thick-walled – толстостенный mandrel – оправка, сердечник loosely – свободно, с зазором fitting – посадка ram – пуансон, плунжер Answer the questions: 1. Why are metals so important in industry? 2. What are the main metalworking processes? 3. Why are metals worked mostly hot? 4. What properties does cold working give to metals? 5. What is rolling? Where is it used? 6. What is extrusion? What shapes can be obtained after extrusion?
7. What are the types of extrusion? Find the following in the text:
Translate into English: 1. Способность металла перекристаллизовываться при высокой температуре используется при горячей обработке. 2. Перекристаллизация – это рост новых, свободных от деформации зерен 3. Во время горячей обработки металл может подвергаться очень большой пластической деформации сжатия. 4. Холодная обработка делает металл тверже и прочнее, но некоторые металлы имеют предел деформации. 5. Листовой прокат может производиться горячим или холодным. 6. Поверхность холоднокатаного листа более гладкая и он прочнее. 7. Поперечное сечение фильеры для экструзии может быть простым или сложнымю 8. Алюминиевые и медные сплавы являются наилучшими для экструзии из-за их пластичности при деформации. 9. Алюминиевые банки, тюбики для зубной пасты являются примерами использования штамповки выдавливанием. 10. Толщина стенки алюминиевой банки определяется зазором между пуансоном и штампом. Text 2. TECHNOLOGICAL PROCESSES Drawing consists of pulling metal through a die. An example of drawing is wire drawing. The diameter reduction that can be achieved in one die is limited, but several dies in series can be used to get the desired reduction. Sheet metal forming (штамповка листового металла) is widely used when parts of certain shape and size are needed. It includes forging, bending and shearing. One characteristic of sheet metal forming is that the thickness of the sheet changes little in processing. The metal is stretched just beyond its yield point (2 to 4 percent strain) in order to retain the new shape. Bending can be done by pressing between two dies. Shearing is a cutting operation similar to that used for cloth. Each of these processes may be used alone, but often all three are used on one part. For example, to make the roof of an automobile from a flat sheet, the edges are gripped and the piace pulled in tension over a lower die. Next an upper die is pressed over the top, finishing the forming operation (штамповку), and finally the edges are sheared off to give the final dimensions. Forging is the shaping of a piece of metal by pushing with open or closed dies. It is usually done hot in order to reduce the required force and increase the metal’s plasticity. Open-die forming is usually done by hammering a part between two flat faces. It is used to make parts that are too big to be formed in a closed die or in cases where only a few parts are to be made. The earliest forging machines lifted a large hammer that was then dropped on the workpiece, but now air or steam hammers are used, since they allow greater control over the force and the rate of forming. The part is shaped by moving or turning it between blows. Closed-die forming is the shaping of hot metal within the walls of two dies that come together to enclose the workpiece on all sides. The process starts with a rod or bar cut to the length needed to fill the die. Since large, complex shapes and large strains are involved, several dies may be used to go from the initial bar to the final shape. With closed dies, parts can be made to close tolerances so that little finish machining is required. Two closed-die forging operations are given special names. They are upsetting and coining. Coining takes its name from the final stage of forming metal coins, where the desired imprint is formed on a metal disk that is pressed in a closed die. Coining involves small strains and is done cold. Upsetting involves a flow of the metal back upon itself. An example of this process is the pushing of a short length of a rod through a hole, clamping the rod, and then hitting the exposed length with a die to form the head of a nail or bolt.
Additional vocabulary: to pull – тянуть in series – сери, последовательно yield point – точка текучести металла shearing – обрезка, отрезание to grip – схватывать lower die - нижний штамп upper die – верхний штамп forming operation – операция штампования open - die forming – ковка в открытом штампе (подкладном) coining – чеканка imprint – отпечаток to hit – ударять required – необходимый hammering – ковка within – внутри, в пределах to enclose – заключать machining – механическая обработка rod – прут, стержень tolerance – допуск upsetting – высадка, выдавливание blow – удар clamp – зажим, зажимать
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Text 3. WELDING Welding is a process when metal parts are joined together by the application of heat, pressure, or a combination of both. The processes of welding can be divided into two main groups: · pressure welding, when the weld is achieved by pressure and
Heat welding is the most common welding process used today. Nowadays welding is used instead of bolting and riveting in the construction of many types of structures, including bridges, buildings, and ships. It is also a basic process in the manufacture of machinery and in the motor and aircraft industries. It is necessary almost in all productions where metals are used. The welding process depends greatly on the properties of the metals, the purpose of their application and the available equipment. Welding processes are classified according to the sources of heat and resistance welding. Other joining processes are laser welding, and electron- Beam wilding. Gas Welding Gas welding is a non-pressure process using heat from a gas flame. The flame is applied directly to the metal edges to be joined and simultaneously to a filler metal in the form of wire or rot, called the welding rod, which is melted to the joint. Gas welding has the advantage of using equipment that is portable and does not require an electric power source. The surfaces to be welded and the welding rod are coated with flux, a fusible material that shields the material from air, which would result in a defective. Are Welding Arc-welding is the most important welding process for joining steels. It requires a continuous supply of either direct or alternating electrical current. This current is used to create an electric arc, which generates enough heat to melt metal and create a weld. Arc welding has several advantages over other welding methods. Arc welding is faster because the concentration of heat is high. Also, fluxes are not necessary in certain methods of arc welding. The most widely used arc-welding processes are shielded metal arc, gas-tungsten arc, gas-metal arc, and submerged arc. Resistance Welding In resistance welding, heat is obtained from the resistance of metal to the flow of an electric current. Electrodes are clamped on each side of the parts to be welded, the parts are subjected to great pressure, and a heavy current is applied for a short period of time. The point where the two metals touch creates resistance to the flow of current. This resistance causes heat, which melts the metals and creates the weld. Resistance welding is widely employed in many fields of sheet metal or wire manufacturing and is often used for welds machines especially in automobile industry. Additional vocabulary: pressure welding – сварка давлением heat welding – сварка нагреванием instead – вместо, взамен bolting – скрепление болтами riveting – клепка basic – основной to manufacture – изготовлять to depend – зависеть от purpose – цель gas welding – газосварка are welding – электродуговая сварка resistance welding – контактная сварка laser welding – лазерная сварка electron - beam welding – электронно-лучевая сварка flame – пламя edge – край simultaneously – одновременно filler – наполнитель wire – проволока rod – прут, стержень to melt – плавить(ся) joint – соединение, стык coated – покрытый flux – флюс fusible – плавкий touching – касание to shield – заслонять, защищать tip – кончик
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Text 4. TYPES OF WELDING Shielded metal are welding In shielded metal-arc welding, a metallic electrode, which conducts electricity, is coated with flux and connected to the other and of the same source of current. An electric arc is formed by touching the tip of the electrode to the metal and then drawing it away. The intense heat of the arc melts both parts to be welded and the point of the metal electrode, which supplies filler metal for the weld. This process is used mainly for welding steels.
Gas-metal are welding In gas-metal welding, a bare electrode is shielded from the air by surrounding it with argon or carbon dioxide gas and sometimes by coating the electrode with flux. The electrode is fed into the electric arc, and melts off in droplets that enter the liquid metal of the weld seam. Most metals can be joined by this process. Submerged are welding Submerged-arc welding is similar to gas-metal arc welding, but in this process no gas is used to shield the weld. Instead of that, the arc and tip of the wire are submerged beneath a layer of granular, fusible material that covers the weld seam. This process is also called electro slag welding. It is very efficient but can be used only with steels.
Additional vocabulary: gas - tungsten welding – сварка оплавлением вольфрамовым электродом в среде инертного газа inert – инертный bare – голый rate – скорость gas-metal arc – аргонодуговая сварка surrounding – окружающий liquid – жидкость, жидкий droplet – капелька carbon dioxide – углекислый газ beneath – под, ноже, внизу layer – слой weld seam – сварной шов semi - automatic – полуавтоматическая to submerge – погружать
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THEME 4 Machine Tools Vocabulary:
workpiece – обрабатываемая деталь, изделие facility – приспособление to allow – позволять, разрешать relative – относительно to lubricate – смазывать fasten – прикреплять, привязывать, застегивать ( to ) screw – винт, привинчивать, навинчивать thread – нить, резьба, нарезка discharge – электр. разряд ( to ) feed ( fed , fed ) – подавать, подача lathe – токарный станок range – ассортимент, диапазон flexible – гибкий, гнущийся, эластичный sharp – острый friction – трение outside – наружный, внешний, снаружи inside – внутри, внутренний to remove – удалять, перемещать to mount – крепить, закреплять to require – нуждаться, требовать to enable – дать возможность, позволять tolerance – допуск close tolerance – жесткий допуск wheel – колесо, круг Text 1. 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 tools: they are 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 system of machine-tools to be used flexibly for the manufacture of a range of products.
Additional vocabulary: machine-tools – станки electrically driven – с электроприводом fluid – жидкость spark erosion – электроискровая обработка by means of – посредством beam – луч drilling – сверление
LATHE Lathe is still the most important machine-tool. It produces parts of circular cross-section by turning the workpiece on its axis and cutting its surface with a sharp stationary tool may be moved sideways to produce a cylindrical part and moved towards the workpiece to control the depth of cut. Nowadays all lathes are power-driven by electric motors. That allows continuous rotation of the workpiece at a variety of speeds. The modern lathe is driven by means of a headstock supporting a hollow spindle on accurate bearings and carrying either a chuck or a faceplate, to which the workpiece is clamped. The movement of the tool, both along the lathe bed and at right angle to it, can be accurately controlled, so enabling a part to be machined to close tolerances. Modern lathes are often under numerical control. Additional vocabulary: circular cross-section – круглое поперечное сечение stationary – неподвижный, стационарный sideways – в сторону spindle – шпиндель variety – разнообразие, разновидность headstock – передняя бабка chuck – зажим, патрон faceplate – планшайба lathe bed – станина станка numerical control – числовое управление Answer the questions:
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Text 3. MILLING MACHINE In a milling machine the cutter (фреза) is a circular device with series of cutting edges on its circumference. The workpiece is mounted (fastened) on a table has that controls the feed against the cutter. The table has three possible movements: longitudinal, horizontal, and vertical; in some cases it can also rotate. Milling machines are the most versatile of all machine tools. Flat or contoured surfaces (фасонная поверхность) may be machined with excellent finish and accuracy. Angles, slots, gear teeth and cuts can be made by using various shapes of cutters.
Shapers and Planers The shaper (поперечно-строгальный станок) is used mainly to produce different flat surfaces. The tool slides against the stationary workpiece and cuts on one stroke, returns to its starting position, and then cuts on the next stroke after a slight lateral displacement. In general, the shaper can make any surface having straight-line elements. It uses only one cutting-tool and is relatively slow, because the return stroke is idle. That is why the shaper is seldom found on a mass production line. It is, however, valuable for tool production and workshops where flexibility is important and relative slowness is unimportant. The planer (продольно-строгальный станок) is the largest of the reciprocating machine tools. It differs from the shaper, which moves a tool past a fixed workpiece because the planer moves the workpiece to expose a new section to the tool. Like the shaper, the planer is intended to produce vertical, horizontal, or diagonal cuts. It is also possible to mount several tools at one time in any or all tool holders of a planer to execute multiple simultaneous cuts. Grinders Grinders (шлифовальные станки) remove metal by a rotating abrasive wheel. The wheel is composed of many small grains of abrasive, bonded together, with each grain acting as a miniature cutting tool. The process gives very smooth and accurate finishes. Only a small amount of material is removed at each pass of the wheel, so grinding machines require fine wheel regulation. The pressure of the wheel against the workpiece is usually very light, so that grinding can be carried out on fragile materials that cannot be machined by other conventional devices.
Additional vocabulary: milling machine – фрезерный станок series – серия, ряд ( to ) cut – резать, срезать, разрез cutting edge – режущий край, острие ( to ) finish – обрабатывать начисто, отделка, доводка с ircumference – окружность longitudinal – продольный to rotate – поворачивать, вращать(ся) versatile – универсальный flat – плоский single - point cutter – одиночный резец contoured – контурный, фасонный slot – прорезь, паз gear teeth – зубы шестерни drill – дрель, сверло, сверлить hole – отверстие wheel – круг, колесо pass – проход abrasive wheel – абразивный круг fragile – хрупкий to enlarge – увеличивать thread – резьба portable – портативный previously – ранее stroke – ход lateral – боковой displacement – смещение idle – на холостом ходу straight – прямой workshop – цех, мастерская holder – держатель to execute – выполнять simultaneous – одновременный multiple – многочисленный, многократный, множественный grinder – шлифовальный станок fine – точный conventional – обычный bonded – скрепленный
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Text4 DIES Dies are tools used for the shaping of solid materials, especially those employed on the pressworking of cold metals. In presswork, dies are used in pairs. The smaller die, or punch, fist inside the larger die, called the matrix or, simply, the die. The metal to be formed, usually a sheet, is placed over the matrix on the press. The punch is mounted on the press and moves down by hydraulic or mechanical force. A number of different forms of dies are piercing dies (пробивной штамп), used for punching holes. Bending and folding dies (загибной) a re designed to make single or compound bends. A combination die is designed to perform more then one of the above operations in one stroke of the press. A progressive die (штамп последовательного действия) permits successive forming operations with the same die. In coining, metal is forced to flow into two matching dies, each of which bears an engraved design (гравированный рисунок).
Wiredrawing Dies In the manufacture of wire, a drawplate (волочильная доска) is usually employed. This tool is a metal plate containing a number of holes, successively less in diameter and known as wire dies. A piece of metal is pulled through the largest die to make a coarse wire. This wire is then drawn through the smaller hole, and then the next, until the wire is reduced to the desired measurement. Wiredrawing dies are made from extremely hard materials, such as tungsten carbide or diamonds.
Thread-Cutting Dies For cutting threads on bolts or on the outside of pipes, a thread-cutting die (резьбовая плашка) is used. It is usually made of hardened steel in the form of a round plate with a hole in the centre. The hole has a thread. To cut an outside thread, the die is lubricated with oil and simply screwed onto an unthreaded bolt or piece of pipe, the same way a nut is screwed onto a bolt. The corresponding tool for cutting an inside thread, such as that inside a nut, is called a tap (метчик). Additional vocabulary: chip – стружка content – содержание inexpensive – недорогой to permit – позволять, разрешать tungsten – вольфрам diamond – алмаз tips – наконечники truing – правка, наводка, заточка die – матрица, штамп, лерка, резьбонарезная плашка, волочильная доска coarse – грубый to employ – применять to pierce – протыкать, прокалывать to punch – пробивать отверстие matching – сочетающийся, парный wire – проволока to force – вдавливать to draw – тащить, волочить thread – резьба hardened – закаленный nut – гайка
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THEME 1 Materials Science and Technology Vocabulary: to fabricate – изготовлять, производить ( to ) need – нуждаться, потребность way – путь, способ, образ (действия) to respond – отвечать, отзываться, реагировать external – внешний, наружный force – сила, усилие elastic – упругий, эластичный permanent – постоянный volume – объем, емкость ( to ) cause – вызывать, причина to subject – подвергать to decrease – исчезать to increase – увеличивать to remain – оставаться to exceed – превышать to eliminate – устранять, ликвидировать Text 1. |
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