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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.

Under the classification of drilling and boring, there are two types of technique: reaming and tapping. Reaming consists of finishing a hole already drilled. Tapping is the process of cutting a thread in a hole.

 

Vocabulary:

1) to mount	-устанавливать; насаживать; монтировать	10) planning	-строгание
2) workbench	-верстак	11) shaping	-фасонирование
3) to house	-помещать	12) broaching	-протяжка
4) drilling	-сверление	13) grinding	-шлифование
5) boring	-расточка	14) honing	-хонингование
6) reaming	-зенкование, развертывание	15) single point tool	-режущий однолезвийный инструмент
7) tapping	-нарезание резьбы	16) to fix	-зажимать, укреплять
8) turning	-точение, токарная обработка	17) to revolve	-вращать(-ся)
9) milling	-фрезерование

 

Exercise 1.5. Прочитайте текст и найдите в нем ответы на следующие вопросы:

1. How may groups can machine tools be classified?

2. What basic operations of shaping metal do machine tools include?

3. What new metal shaping methods were developed during the past two decades?

4. What do these new methods employ?

5. What is drilling?

6. What is boring?

7. What differs drilling machines from boring machines?

8. What is the difference between reaming and tapping?

Exercise 1.6 Translate the sentences:

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

METALS

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

6. размер зерен

7. форма зерен

8. закалка

9. отжиг

10.волочение

11.прокатка

12.ковка

13.экструзия

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:

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...

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.

3. Чем меньше зерна, тем тверже металл.

4. Закалка и отжиг изменяют форму и размер зе­рен в металлах.

5. Легирование изменяет структуру зерен и свой­ства металлов.

6. Металл деформируется и разрушается из-за ус­талости и ползучести.

 

Text В: STEEL

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

6. ковкость

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

14.упрочнять

15. добавление марганца (кремния, хрома, вольфра­ма, молибдена, ванадия)