Find the following words and word combinations in the text свойства металлов решение
1. How has the meaning of energy security expanded over time?
2. Do you agree that climate-inclusive approach should beintegrated into the concept of energy security? Give your reasons.
3. What are the international and domestic factors turning energy poverty into a serious problem and how could it be better addressed?
4. What two key aspects does the universality of energy security imply?
5. What steps has international community taken over the last decade to formulatecommon principles of energy security? What actions do these principles specify?
6. How is the international energy security defined in a draft Convention presented by the Russian Federation? Was it comprehensive?
7. Why were the negotiations on the “International Energy Charter” of 2014 important for the energy community?
8. What contradictions should energy consumers and producers overcome to reach an agreement on a common concept of international energy security?
9. What is common concept of international energy security supposed to be based on?
10. What are the tools ensuring security of supply?
11. How do OPEC and GECF attempt to agree with importers to ensure security of demand? Have they succeeded?
12. Why is security of supply and demand important for the economies of energy consuming and producing countries?
13. What is the transit countries position in regard to the concept of energy security?
14. What does the future of common concept of energy security depend on?
Task 3. Scan the text again and be ready to speak on the points below :
1. The elements of the expanded concept of energy security.
2. Relation of energy poverty to energy security (domestic and international aspects).
3. The components of universal core principles of energy security listed in the G8 Declaration.
4. The importance of the notion of security of demand for a common concept of energy security.
5. The basics of a common concept of international energy security.
6. The role of security of demand and supply for the producing and importing countries respectively.
LANGUAGE FOCUS
Task 1. Find in the text all possible word combinations with the following words. Translate them into Russian:
Security, energy, diversification, supply, demand, transit
Task 2. Give Russian equivalents of the word combinations printed in bold in the text.
Task 3. Find in the text English equivalents of the following word combinations:
1. справедливая/разумная/приемлемая цена
2. недостаточное инвестирование
3. подход к энергетической безопасности, учитывающий проблемы изменения климата
4. приуменьшать значение
5. ценовая доступность энергетических потоков
6. система социального обеспечения
7. решать как проблему национальной энергетической безопасности
8. надежность предложения
9. диверсификация спроса и предложения на энергоносители
10. неделимость понятия устойчивой глобальной энергетической безопасности
11. надежная и бесперебойная поставка
12. страны-производители, страны транзита и страны-потребители энергоносителей
13. потребление энергии от первичных источников
14. накопление запасов
15. доходы от экспорта
Task 4. Match the words from columns A and B to make up collocations. Give their Russian equivalents.
A | B |
1. environmental and social 2. fossil 3. energy 4. energy 5. supply 6. to meet 7. energy 8. to fall 9. energy 10. guaranteed 11. fixed 12. vertical 13. supply 14. rent | a) supplies b) short c) challenges d) sustainability e) offtake f) integration g) pricing h) sources i) expansion j) sharing k) market l) security m) subsidies n) fuels |
Task 5. Match the following word-combinations with their corresponding definitions and translate them into Russian.
1. energy security; 2. energy supply; 3. energy poverty; 4. energy subsidies; 5. energy diversity 6. fossil fuel 7. renewable resources 8. vertical integration | a) lack of access to modern energy services b) the uninterrupted availability of energy sources at an affordable price c) Fuel that was formed in the earth in prehistoric times from remains of living-cell organisms d) An arrangement whereby the same company owns all the different aspects of making, selling, and delivering a product or service e) measures that keep prices for consumers below market levels or for producers above market levels, or reduce costs for consumers and producers f) policy that encourages the development of energy technologies to diversify energy supply sources, thus reducing reliance on conventional fuels g) are virtually inexhaustible in duration but limited in the amount of energy that is available per unit of time h) energy made available for future disposition. Supply can be considered and measured from the point of view of the energy provider or the receiver. |
Reliability is a basic requirement, plant or machine. The most ingenious machine is nothing but useless unless it is reliable.
At present the main defect in any machine is the different service life of its parts. The first to break down are parts with friction, the most numerous in any machine. Until quite recently scientists differed in there explanations of why parts subjected to friction break.
At present scientists are engaged in research into friction and were-and-tear resistance. The results of their comprehensive research will extend the useful life of units with friction by thirty to fifty percent as compared with what we have now.
Sufficient reliability and long service life of highly complicated automatic complexes, spaceships and assembly lines can be ensured by the high quality of their components, their accurate assembly and continuous checking while in operation, as well as by detecting faults as soon as they appear. This means that instruments are necessary for checking metal billets; all kinds of test installations and multiple switching control devices by which temperature, pressure and density in any part of a system may be inspected a number of times over a period of only one second. We need diagnostic system and many different types of flaw detectors and sensors because, as is known, reliability is the key which opens the way to large-scale automation.
Why is the service life of different machine parts different?
What factors do the service life and reliability of complicated systems depend on?
In what ways can the quality of machine parts be inspected?
A major advance in twentieth century manufacturing was the development of mass production techniques. Mass refers to manufacturing process in which an assembly line, usually a conveyer belt, moves the product to stations where each worker performs a limited number of operations until the product is assembled. In the automobile assembly plant such systems have reached a highly-developed form. A complex system of conveyer belts and chain drives car parts to workers who perform the thousands of necessary assembling tasks.
Mass production increases efficiency and productivity to a point beyond which the monotony of repeating an operation over and over slows down the workers. Many ways have been tried to increase productivity on assembly lines: some of them are as superficial as piping music into the plant or painting the industrial apparatus in bright colours; others entail giving workers more variety in their tasks and more responsibility for the product.
These human factors are important considerations for industrial engineers who must try to balance an efficient system of manufacturing with the complex needs of workers.
Another factor for the industrial engineer to consider is whether each manufacturing process can be automated in whole or in part. Automation is a word coined in the 1940s to describe process by which machines do tasks previously performed by people. The word was new but the idea was not. We know of the advance in the development of steam engines that produced automatic valves. Long before that, during the Middle Ages, windmills had been made to turn by taking advantage of changes in the wind by means of devices that worked automatically.
Automation was first applied to industry in continuous-process manufacturing such as refining petroleum, making petrochemicals, and refining steel. A later development was computer-controlled automation of assembly line manufacturing, especially those in which quality control was an important factor.
Text D. FIVE BASIC TECHNIQUES
The variety and combination of machine tools are unlimited today. Some are small and may be mounted on a workbench. Others are so large that are housed in special buildings.
Large or small machine tools can be classified in five main groups according to the five basic techniques of shaping metal. These basic operations include drilling and boring (including reaming and tapping), turning, milling, planning (including shaping and broaching) and grinding (including honing). Each machine performs one or more of these operations. Variations of five basic techniques are used for special situations. There are, for example, machines that combine two of these techniques, as in a boring, drilling and milling machine or a combination of milling and planning machine.
In addition to the five basic techniques there are newer metal shaping methods developed during the past two decades. These new methods employ corrosion, erosion and force characteristics of chemicals, electricity, magnetism, liquids, sound and light.
Drilling and boring. Drilling is a basic machine shop technique. It consists of cutting a round hole by means of a rotating drill. Boring, on the other hand, is the process of finishing a hole already drilled by means of a rotating single-point tool. On some boring machines, the tool is in a fixed position and the work revolves; on others the work is held fixed and the tool revolves.
How may groups can machine tools be classified?
What basic operations of shaping metal do machine tools include?
What new metal shaping methods were developed during the past two decades?
What do these new methods employ?
What is drilling?
What is boring?
What differs drilling machines from boring machines?
What is the difference between reaming and tapping?
1. Forging is one of the leading technological processes of modern industry.
2. These machines were built up by the workers of our plant for three hours.
3. All these forged parts were made of different materials.
4. The students of the machine-building industry were shown various manufacturing processes.
5. This part was made of steel by casting
6. The main parts of these machines were produced by forging.
7. The machine-building plant of our town produces these machine-tools (металлорежущие станки).
8. The loss of metal in chips in forging process is reduced.
9. The selecting of the most suitable method of forging entails the minimum consumption of metal.
10. The art of drawing metal has developed very rapidly in the last 20 years.
UNIT 2
Text A: METALS
Text B: STEEL
Text C: METHODS of STEEL HEAT TREATMENT
Text A: METALS
Metals 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 vary 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 grains. In general, a metal with small grains will be harder and stronger than one with coarse grains.
Heat treatment such as quenching, tempering, or annealing 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 such as lathe, milling machine, shaper and grinder.
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.
Vocabulary:
property — свойство
metallurgy — металлургия
separation — разделение, отстояние
dense — плотный
arrangement — расположение
regularly — регулярно, правильно
to slide — скользить
malleable — ковкий, податливый, способный деформироваться
bent pp of bend — гнуть
to fracture — ломать
ductile — эластичный, ковкий
to draw — волочить, тянуть
wire — проволока
lead — свинец
iron — железо, чугун
grain — зерно
to depend — зависеть
size — размер, величина
shape — форма, формировать
composition — состав
coarse — грубый, крупный
treatment — обработка
quenching — закалка
tempering — отпуск после закалки, нормализация
annealing — отжиг, отпуск
rolling — прокатка
to hammer — ковать (напр. молотом)
extrusion — экструзия
metal fatigue — усталость металла
creep — ползучесть
stress — давление,
failure — повреждение, разрушение
vessel — сосуд, котел, судно
lathe — токарный станок
milling machine — фрезерный станок
shaper — строгальный станок
grinder — шлифовальный станок
to melt — плавить, плавиться расплавить
to cast — отливать, отлить
mould — форма (для отливки)
General understanding:
1. What are metals and what 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 do 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?
Exercise 2.1. Find the following words and word combinations in the text:
1. Свойства металлов
2. расстояние между атомами
3. правильное расположение
4. сильно отличаются по своим свойствам
5. кристаллическая структура
14. структура и свойства зерна
15. горячая обработка
16. усталость металла
17. ползучесть металла
18. плавка и отливка в формы
19. способы обработки металла
Exercise 2.2. Complete the following sentences:
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.
10. All metals can be formed by.
12. Metals can be worked using.
Exercise 2.3. 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.
The most important metal in industry is iron and its alloy — steel. Steel is an alloy of iron and carbon. It is strong and stiff, but corrodes easily through rusting, although stainless and other special steels resist corrosion. The amount of carbon in a 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 cent carbon, are hard and brittle and are used in cutting tools, surgical instruments, razor blades and springs. Tool steel, also called silver steel, contains about 1 per cent 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 form 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.
Vocabulary:
alloy — сплав
carbon— углерод
stiff — жесткий
to corrode — разъедать, ржаветь
rusty — ржавый
stainless — нержавеющий
to resist — сопротивляться
considerably — значительно, гораздо
tough — крепкий, жесткий, прочный, выносливый
forging — ковка
welding — сварка
brittle — хрупкий, ломкий
cutting tools — режущие инструменты
surgical instruments — хирургические инструменты
blade — лезвие
spring — пружина
inclusion — включение
to affect — влиять
manganese — марганец
silicon — кремний
rust-proof — нержавеющий
nitrogen — азот
tungsten — вольфрам
General understanding:
1. What is steel?
2. What are the main properties of steel?
3. What are the drawbacks of steel?
4. What kinds of steel do you know? Where are they used?
5. What gives the addition of manganese, silicon and chromium to steel?
6. What can be made of mild steels (medium-carbon steels, high-carbon steels)?
7. What kind of steels can be forged and welded?
8. How can we get rust-proof (stainless) steel?
9. What is used to form a hard surface on steel?
10. What are high-speed steels alloyed with?
Exercise 2.4. Find the following words and word combinations in the text:
1. сплав железа и углерода
2. прочный и жесткий
3. легко коррозирует
4. нержавеющая сталь
5. низкое содержание углерода
7. листовое железо, проволока, трубы
8. конструкционные стали
9. пригодны для ковки и сварки
10. твердый и хрупкий
11. режущие инструменты
12. хирургические инструменты
13. инструментальная сталь
15. добавление марганца (кремния, хрома, вольфрама, молибдена, ванадия)
Text С: METHODS OF STEEL HEAT TREATMENT
Quenching is a heat treatment when metal at a high temperature is rapidly cooled by immersion in water or oil. Quenching makes steel harder and more brittle, with small grains structure.
Tempering is a heat treatment applied to steel and certain alloys. Hardened steel after quenching from a high temperature is too hard and brittle for many applications and is also brittle. Tempering, that is re-heating to an intermediate temperature and cooling slowly, reduces this hardness and brittleness. Tempering temperatures depend on the composition of the steel but are frequently between 100 and 650 °C. Higher temperatures usually give
Annealing is a heat treatment in which a material at high temperature is cooled slowly. After cooling the metal again becomes malleable and ductile (capable of being bent many times without cracking).
All these methods of steel heat treatment are used to obtain steels with certain mechanical properties for certain needs.
Vocabulary:
to immerse — погружать
to apply — применять
intermediate — промежуточный
oxide film — оксидная пленка
annealing — отжиг, отпуск
cracking — растрескивание
General understanding:
1. What can be done to obtain harder steel?
2. What makes steel more soft and tough?
3. What makes steel more malleable and ductile?
4. What can serve as the indicator of metal temperature while heating it?
5. What temperature range is used for tempering?
6. What are the methods of steel heat treatment used for?
Exercise 2.5. Translate into English the following words and word combinations:
1. температура нормализации
2. мелкозернистая структура
3. быстрое охлаждение
4. закаленная сталь
6. окисная пленка
7. индикатор температуры
8. медленное охлаждение
UNIT 3
METALWORKING
Text A: METALWORKING PROCESSES: ROLLING, EXTRUSION.
Text B: DRAWING, FORGING, SHEET METAL FORMING.
Text C: METALWORKING AND METAL PROPRTIES.
Text A: METALWORKING PROCESSES
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:
2. extrusion,
5. sheet-metal forming.
During the first four processes metal is subjected to large amounts of strain (deformation). But 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 temperature. 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 temperature. 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 is the most common metalworking process. More than 90 percent of the aluminum, steel and copper produced is 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 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 examples 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 impact extrusion (also called 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.
Vocabulary:
useful — полезный
shape — форма, формировать
rolling — прокатка
extrusion — экструзия, выдавливание
drawing — волочение
forging — ковка
sheet — лист
to subject — подвергать
amount — количество
condition — состояние, условие
perform — выполнять, проводить
to harden — делаться твердым, упрочняться
at least — по крайней мере
common — общий
billet — заготовка, болванка
orifice — отверстие
die — штамп, пуансон, матрица, фильера, волочильная доска
cross section — поперечное сечение
window frame — рама окна
tube — труба
hollow — полый
initial — первоначальный, начальный
thick-walled — толстостенный
mandrel — оправка, сердечник
impact — удар
loosely — свободно, с зазором
fitting — зд. посадка
ram — пуансон, плунжер
force — сила
gap — промежуток, зазор
to determine — устанавливать, определять
General understanding:
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?
Exercise 3.1. Find the following in the text:
1. могут легко деформироваться
3. подвергать большим деформациям
4. зерна свободные от деформации
5. температура перекристаллизации
6. пластическая деформация сжатия
7. самый обычный процесс обработки металла
8. самое обычное изделие проката
9. отверстие фильеры
11. сложное сечение
12. пустотелые детали
13. свободно входящий плунжер
14. зазор между плунжером (пуансоном) и штампом
15. толщина стенки
Exercise 3.2. 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 сложным.
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 пунсоном и штампом.
Text В: DRAWING
Drawing consists of pulling metal through a die. One type 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
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 piece 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 forging 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 forging 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.
2. What are the units of density? Where low density is needed?
3. What are the densities of water, aluminium and steel?
4. A measure of what properties is stiffness? When stiffness is important?
5. What is Young modulus?
6. What is strength?
7. What is yield strength? Why fracture strength is always greater than yield strength?
8. What is ductility? Give the examples of ductile materials. Give the examples of brittle materials.
9. What is toughness?
10. What properties of steel are necessary for the manufacturing of: a) springs, b) car body parts, c) bolts and nuts, d) cutting tools?
11. Where is aluminium mostly used because of its light weight?
Exercise 4.3. Find the following words and word combinations in the text:
1. количество массы в единице объема
2. килограмм на кубический метр
3. мера сопротивления деформации
4. отношение приложенной силы на единицу площади к частичной упругой деформации
5. жесткая конструкция
6. прочность на сжатие
7. способность материала деформироваться не разрушаясь
8. поглощать энергию путем деформации
9. обратно пропорционально квадрату размера дефекта
10. постепенное изменение формы
11. повышенные температуры
12. высокие растягивающие усилия
Exercise 4.4. Translate into English the following:
1. Плотность измеряется в килограммах на кубический метр.
2. Большинство материалов имеют более высокую плотность, чем вода и тонут в воде.
3. Плотность материала очень важна, особенно в авиации.
4. Модуль Юнга — отношение приложенной силы к упругой деформации данного материала.
5. Чем более металл жесткий, тем менее он деформируется под нагрузкой.
6. Когда металл растягивают, он сначала течет, то есть пластически деформируется.
7. Свинец, медь, алюминий и золото — самые ковкие металлы.
8. Сопротивление ползучести является очень важным свойством материалов, которые используются в авиационных моторах.
UNIT 5
MATERIALS TECHNOLOGY
TEXT A. CHANGES IN MATERIALS TECHNOLOGY
TEXT В. WORKING WITH NEW MATERIALS
TEXT C. METAL CASTING - A BASIC MANUFACTURING PROCESS
TEXT D. METAL CUTTING
TEXT A. CHANGES IN MATERIALS TECHNOLOGY
Since the technology of any age is founded upon the materials of the age, the era of new materials will have a profound effect on engineering of the future.
Not only new materials, but related, and equally important, new and improved and less wasteful processes for the shaping, treating and finishing of both traditional and new materials are continuously being developed.
It is important that an engineer should be familiar with them. These include casting, injection molding and rotational molding of components of ever increasing size, complexity and accuracy; manufacture of more complex components by powder metallurgy techniques; steel forming and casting processes based on new, larger and more mechanized machines, giving reduced waste and closer tolerances; the avoidance of waste in forging by the use of powder metallurgy or cast pressforms and new finishing processes for metals and plastics, just to name a few. A high proportion of these processes is aimed at the production of complex, accurate shapes with a much smaller number of operations and with far less waste than the traditional methods of metal manufacture.
Joining techniques have developed to unprecedented level of sophistication and are also providing opportunities for economies. It is necessary to mention that these newer techniques allow the manufacture of complicated parts by welding together simpler sub-units requiring little machining; such assemblies can be made from a variety of materials. The methods can also be used effectively for assembly, allowing savings to be made in both materials and machine utilization.
The brief review of new processes above has indicated that a new materials technology is rapidly emerging, providing new opportunities and challenges for imaginative product design and for more efficient manufacture.
Exercise 5.1.Translate the sentences, which of them are not correct.
1. Joining techniques have developed to the high level of sophistication.
Joining techniques are developing to a high level of sophistication. 2. The review of new processes has indicated that a new materials technology is rapidly developing. The review of new processes is indicating that a new materials technology is rapidly developing. 3. The avoidance of waste in forging has been achievedby the use of powder metallurgy. The avoidance of waste in forging is being achieved by the use of powder metallurgy.
Exercise 5.2.Translate the sentences:
On receiving his diploma the engineer does not finish his education.
When the engineer receives his diploma he does not finish his education.
Exercise 5.3. Answer the questions:
1. Is materials technology changing nowadays? 2. What do new manufacturing processes include? 3. What are they aimed at? 4. Can complicated parts be manufactured by welding together simpler sub-units? 5. Can these assemblies be made from a variety of materials? 6. What has the brief review of new materials and processes indicated? 7. Why is it necessary for an engineer to know these processes?
TEXT В. WORKING WITH NEW MATERIALS
A successful design is almost always a compromise among highest performance, attractive appearance, efficient production, and lowest cost. Achieving the best compromise requires satisfying the mechanical requirements of the part, utilizing the most economical material that will perform satisfactorily, and choosing a manufacturing process compatible with the part design and material choice. Stating realistic requirements for each of these areas is of the utmost importance.
The rapidity of change in materials technology is typified by the fact that plastics, a curiosity at the turn of the 20th century, are now being used in volumes which have for many years exceeded those of all the non-ferrous metals put together, and which are beginning to rival steel.
The changes which are taking place are, of course, not only quantitative. They are associated with radical changes in technology — in the range and nature of the materials and processes available to the engineer.
The highest specific strength (i.e. the strength available from unit weight of material) now available comes from non-metals, such as fibreglass, and from metals, such as berillium and titanium, and new ultrahigh strength steels.
Fibre technology, in its modern form, is of more recent origin than plastics, but composites based on glass and/or on carbon fibres are already being applied to pressure vessels, to lorry cabs and to aircraft engines, and may well replace aluminium for the skin and structure of aircraft. An all-plastic car has been exhibited: nearly the whole car, except the engine and transmission is of plastics or reinforced plastics.
It is not only plastics and their reinforcement which are changing the materials scene. Ceramics too are gaining an increasing foothold. Their impact as tooling materials in the form of carbides, nitrides and oxides is also well known — cutting tools made of these materials are allowing machining rates which had previously been considered quite impossible,
Silicon nitride seems to offer particular promise for a wide variety of applications. Among these is liquid metal handling. Pumps for conveying liquid aluminium are now on trial which could revolutionize the foundry industry. Silicon nitride is also being tested for the bearing surfaces of the Wankel rotary engines which are being developed as potential replacements for the conventional piston engines of our motor cars. And ceramic magnets have replaced the traditional steel pole-piece plus copper field coil for providing the engineering field for many electric motors.
It is clear that the number of combinations of all kinds of original trends in the production of new materials is practically unlimited. This, in turn, opens new realms for the designing of still cheaper, effective and unthinkably perfected, compared to that we have today, machines and mechanisms.
Exercise 5.4. Make up questions to the text B.
TEXT C. METAL CASTING -A BASIC MANUFACTURING PROCESS
One of the basic processes of the metalworking industry is the production of metal castings. A casting may be defined as "a metal object obtained by allowing molten metal to solidify in a mold", the shape of the object being determined by the shape of the mold cavity. A foundry is a commercial establishment for producing castings.
Numerous methods have been developed through the ages for producing metal castings but the oldest method is that of making sand castings in the foundry. Primarily, work consists of melting metal in a furnace and pouring it into suitable sand molds where it solidifies and assumes the shape of the mold.
Most castings serve as details or component parts of complex machines and products. In most cases they are used only when they are machined and finished to specified manufacturing tolerances providing easy and proper assembly of the product.
At present the foundry industry is going through a process of rapid transformation, owing to modern development of new technological methods, new machines and new materials. Because of the fact that casting methods have advanced rapidly owing to the general mechanical progress of recent years there is today no comparison between the quality of castings, the complexity of the patterns produced and the speed of manufacture with the work of a few years ago.
TEXT D. METAL CUTTING
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.
Turningmachines(lathes).4.Millingmachines.
Drillingmachines.5.Grindingmachines.
Boringmachines.
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.
1. Метали – це щільні матеріали тому, що в металах між атомами мала відстань.
2. Метали мають кристалічну структуру із-за правильного положення атомів.
3. Чим менші зерна, тим твердіший метал.
4. Закалка і відпал змінюють форму і розмір зерен в металах.
5. Легування змінює структуру зерен і властивості металів.
6. Метал деформується і руйнується із-за втоми і повзучості.
METALWORKING PROCESSES
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:
5. sheet-metal forming.
During the first four processes metal is subjected to large amounts of strain (deformation). But 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 temperature. 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 temperature. 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 is 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. Aluminium window frames are the examples of complex extrusions.
Tubes or other hollow parts can also be extruded. The j 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 impact extrusion (also called back-extrusion) (штамповка видавлюванням), 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 aluminium beer cans.
Add to your active vocabulary:
shape — форма, формувати
extrusion — екструзія, видавлювання
to subject — піддавати
condition — стан, умова
perform — виконувати, проводити
to harden— робитися твердин, зміцнюватися
at least — принаймні
billet — заготовка, болванка
die — штамп, пуансон, матриця, фільєра, волочильна дошка
cross section — поперечний розріз
window frame — віконна рама
mandrel — оправка, сердечник
loosely — вільно, з зазором
ram — пуансон, плунжер
gap — проміжок, зазор
to determine — встановлювати, визначати
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?
© 2014-2022 — Студопедия.Нет — Информационный студенческий ресурс. Все материалы представленные на сайте исключительно с целью ознакомления читателями и не преследуют коммерческих целей или нарушение авторских прав (0.012)
Читайте также: