ЗНАЕТЕ ЛИ ВЫ?

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This type of welding is a pressure process, as is forge welding. It consists of heating to their plastic temperature the surfaces of parts to be joined, then applying pressure mechanically to achieve complete union of the parts. The heating is accomplished by passage of a heavy, localized electric: current. Alternating current of common commercial voltage is employed for this purpose.

In all types of resistance welding, selection of proper electrodes is important to the success of the process. Electrodes must possess a high degree of thermal and electrical conductivity, and they also must possess strength and hardness.

Types of resistance welding are: spot welding; butt welding; flash welding; percussion welding; seam welding; projection-welding.

Spot Welding— this process consists of holding two more metals between suitable electrodes which pass a heavy current through the materials to be welded.

The electrodes then arc forced together by pressure of sufficient force to join the surfaces of the base metals in a spot.

A spot-welding machine is the simplest form of resistance-welding device; therefore it is widely adapted throughout the metal-working industry.

Butt-Welding — By this process the parts to be welded are gripped mechanically and pressed together while heat is ge­nerated by passage of a heavy current through the area of the joint.

Butt welding is used extensively for resistance welding work. Pipes, tubing, bars, rods, light- and medium-weight structural shapes, etc., may be butt welded.

 

Word List:

forge welding – кузнечне зварювання

complete union of the parts – прочне з’єднання частин

accomplish – здійснювати, виконувати

resistance welding – контактне зварювання

degree of thermal and electrical conductivity - ступінь термоелектричної провідності

hardness– твердість

spot welding –точкове зварювання

butt welding – стикове зварювання

flash welding – стикова контактна зварка оплавленням

percussion welding – ударна зварка

seam welding – шовна зварка

projection-welding. – рельєфна зварка

metal-working industry – металообробна промисловість

Questions:

1. What does electric welding consist of?

2. What kind of welding is it?

3. What is spot (butt) welding?

IW # 11 ELECTRIC WELDING (PART 2)

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Flash Welding— this is another type of butt welding, the difference consisting in the method of heating the base metals. The electrodes are clamped to the parts to be joined, and a heavy current is passed through them. The movable electrode brings the surface of the metal it holds into contact, with the surface of the metal held in the stationary electrode. Just be­fore the two pieces meet, an arc developed in the short gap causes sufficient heat to make the surface to be joined plastic.

Percussion Welding—this process is similar to flash welding inasmuch as it-relies upon a sudden discharge of electrical energy (produced by the arc) at the joint to generate Sufficient heat to make the surfaces to be joined plastic. The pressure required to accomplish the weld at the proper moment is obtained by employing a heavy spring.

Seam Welding— this is a resistance-welding process which consists of passing two or more base metals between electrodes which are in the form of rollers. The current is transmitted through the electrodes to the metals. The mechanical pressure required for forcing them together, as well as the current is transmitted by the roller-shaped electrodes. The welded joint thus produced is similar to a seam made in cloth.

Refrigerators, metal containers, gasoline tanks, automobile mufflers, aircraft fabrications, pipes for furnaces and stoves, and other products requiring pressure-tight seams are rapidly produced by seam welding.

 

Word List:

flash welding – стикова контактна зварка оплавленням

movable – рухомий

stationary electrode – нерухомий електрод

to accomplish – забезпечувати

to transmit – передавати

gasoline tanks – бензобаки

mufflers – шумоглушники

 

Questions:

1. What is flash welding?

2. What does percussion welding consist of?

3. What is seam welding?

4. What way is the welded joint produced?

5. What kind of devices are rapidly produced by seam welding?

IW #12 ELECTRIC WELDING (PART 3-4)

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Projection Welding.— This process is similar to spot welding and consists of joining two pieces of metal, one or both of which have mechanically formed projections. The purpose of the projection is to localize the current.

The current and pressures required for this type of welding are heavier than those applied in spot welding. Various sheet metal parts used in automobile and aircraft production are welded by this process.

Electric Arc Welding.— This is a fusion-welding process in which surfaces to be joined are fused by the heat of an electric arc. By bringing the work and the electrode together as conductors, an electric circuit is established; then, by separating the conductors, an electric arc is created in which the electrical energy is converted into heat.

Word List:

projection-welding. – рельєфна зварка

projection – шов

sheet metal parts – деталі з листового заліза

 

Questions:

1. What is projection welding?

2. What is the purpose of the projection?

3. What does electric arc welding consist of?

4. What way is an electric arc created?

IW #13 MODAL VERBS

Модальные глаголы эквиваленты (Modals)

Модальные глаголы (Modal Verbs) и их эквиваленты (Equivalents of Моdal Verbs) часто назьшают одним термином Modals.

1. Модальные глаголы имеют следующие значения:

(1)Can/could — возможность, умение (в настоящем и прошедшем времени)

He canspeak English. Он может/умеет говорить по-английски.

He could translate the text. Он мог перевести этот текст.

(2)could — просьба (в настоящем времени)

CouldI speak to Mr Brown? Можно поговорить с г-ном Брауном?

(3) may — разрешение

May I come in? Можно войти?

(4)should — рекомендация, совет

You should be more attentive. Вы должны быть более внимательны.

(5) must — долг, настоятельная рекомендация

I mustgo now... Я должен идти...

You mustsee this film. Вы должны посмотреть этот фильм.

2. Эквиваленты модальных глаголов имеют следующие значения:

(1) to be able (эквивалент саn) — возможность (в прошлом и будущем времени)

I was able to translate the text. Я смог перевести этот текст.

I shall be able to meet him Я смогу встретить его завтра.

(2) to be (эквивалент must) — долженствование (в соответствии с планом, договоренностью)

The interview isto start at 9.00 Интервью должно начаться в 9 час.

(3) to have (эквивалент must) долженствование (в силу необходимости или вынужденности)

I haveto work hard. Я должен (вынужден) много работать,

I shall have to work till 6 tomorrow. Завтра я должен (вынужден) буду ра­ботать до 6.

Note:

После модальных глаголов инфинитивы употребляются без частицы to.

I could come. Я мог придти (но не пришел).

I was able to come. Я смог придти (и пришел).

 

TEST

1. Can/could/be able to.Fill in:

A)can B)could C)can’t

D)couldn’t E)be able to

1. They had fish hooks so they ____ catch fish.

2. The raft is so small we ____ lie down comfortably.

3. Jane has got two books so she ____ read any of them.

4. They didn’t have any shampoo so they ____ wash their hair.

5. When the ship disappeared, Mary cried and cried. She ____ stop crying.

6. They won’t ____ to drive a car until they are eighteen.

7. ____ they hear it before they saw it?

8. When she was a baby, she ____ only cry.

9. You ____ enter the club without a card.

10. You ____ do it even if you tried.

11. He used to ____ speak Italian well.

12. Cheques ____be accepted only with a bank card.

 

2. Must/may/might. Fill in.

A)must B)may C)might

1. ____ I borrow your ruler?

2. It isn’t certain, but he ____ be a millionaire in two years’ time.

3. That ____ be Charlie. He said he would be here about now.

4. You ____ make a little less noise.

5. Jane ____ still be in her office, but she usually leaves before six.

6. The house repairs _____ cost more than the house is worth.





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