Vocabulary:

pressurewelding – зварювання під тиском,riveting – клепка, клепання, flux – флюс,fusible – плавкий, toshield – затуляти, захищати, tip – кінчик, край,filler – наповнювач,heatwelding –зварювання нагріванням, bolting – скріплення болтами, arcwelding – електродугове зварювання, flame – полум’я,rod – прут, стержень, coated – покритий, simultaneously – одночасно

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, when the weld is achieved by heat. 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 pressure used: gas welding, arc welding, and resistance welding. Other joining processes are laser welding, and electron-beam welding.

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 rod, 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 weld.

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 made by automatic or semi-automatic machines especially in automobile industry.

Ex. 12. Answer the questions:

1. How can a process of welding be defined?

2. What are the two main groups of processes of welding?

3. How can we join metal parts together?

4. What is welding used for nowadays?

5. Where is welding necessary?

6. What do the welding processes of today include?

7. What are the principles of gas welding?

8. What kinds of welding can be used for joining steels?

9. What does arc welding require?

10. What is the difference between the arc welding and shielded-metal welding?

Ex. 13. Read and render the text:

In general, the elements fall into two main categories: metals and non-metals.

The metals are those, which have the bright luster and other characteristics which are usually associated with such substances as iron, silver, zinc and tin, while the non-metals are those substances which do not have characteristics of metals.

By far the greater number of elements are known to be metals, since the transition elements are all metals. The elements could be still further subdivided into five groups, three of which being metallic and two of which being non-metallic.

Unit 14

Text A. Laser Light Text B. Machine-Tools Grammar: The Objective Infinitive Construction

Text A

LASER LIGHT

differ – відрізнятися candle – свічка wave – хвиля

illuminate – освітлювати scattering – розсіювання pierce – проколоти

Notes on the Text

In brief – коротко

More or less – більш менш

Result from the fact – відбуваються через те, що

Light-scattering phenomena – явища розсіювання світла

How does laser light differ from ordinary light? In brief, it is much more intense, directional, monochromatic and сoherent. We know the light emitted by an ordinary source such as candle or an incandescent lamp to consist of uncoordinated waves of many different lengths, that is, it is incoherent and more or less white.

The scientists found the waves of laser light to be coordinated in space and time and to have nearly the same length.This coherence and chromatic purity and also intensity oflaser light result from the fact that in a laser excited atoms are stimulated to radiate light before they have had time to do so spontaneously and independently. The directionality of laser light arises from the geometry of the laser.

These properties of laser light suggest many uses for it both in technology and in physics. The scientists considerlaser light to be different from ordinary light even when it merely illuminates a surface. The surface looks grainy and sparkles.

By means of some instruments it has become possibleto examine materials and physical phenomena in new ways. Among the most interesting applications of the laser the probing of materials by the study of their scattering of light should be mentioned.

The laser is being applied to probe the internal structure and behaviour of molecules by examining the light-scattering phenomena. Many investigators are working at the development of coherent light sources, those ones whose wave-length can be changed.

Many amplifiers and oscillators have been constructed for this purpose lately.

Laser light is applied in many fields such as medicine, biology, industry and so on. We can say scientists made laser light serve man.

The scientists found the energy density of the image formed by a lense in a laser beam to be used to heat, melt oreven vaporize small areas of any material. Laser is also used to pierce holes in diamond.

Soon laser is to be used to cut a wide range of materials including wood and paper.

The scientists work hard to use laser in all fields of scienceand life. They expect laser to be widely used almost everywhere. It will be used for the well-being of people.

Ex. 1. Answer the following questions:

1. What is the difference between laser light and ordinary light? 2. What did the scientists find out about the waves of laser light? 3. What do the properties of laser light suggest? 4. Why did it become possible to examine somematerials in a new way? 5. Which is the most interesting application of laser light well known to everybody? 6. Where else can laser be applied? 7. Why is the discovery of laser light so important? 8. What are many scientists working at?

Ex. 2. Form words of the same root using the prefixes "in-", "im-", "dis-","un-":

Direct, different, dependent, visible, possible, advantage, pure, coordinated, definite.

Ex. 3. Translate the following sentences paying attention to the meanings of "much":

1. This acid is much stronger than that you used before. 2. This reaction depends much on the surrounding air. 3. There is much iron in this deposit. 4. He works much in the laboratory. 5. He likes his work very much. 6. They had to workwith the solution containing as much as 95% of organic solvents.7. There is much glassware in our laboratory.

Ex.4. Translate the following sentences:

Note: to light – світити light – світло

Light – світлий, легкий

1. Light weight metals are required in the manufacture of aircraft equipment. 2. Silver halides darken when exposed to white light. 3. The production of light is the secondary phenomenon in those cases in which the energy of activation is large. 4. Aluminium is a light metal, which exhibits a silvery luster. 5. The first electric power station built in this region lighted the houses and industrial enterprises. 6. The amount of light radiated by an atomic bombis so great that one could hardly imagine it.7.The laboratory is lighted very badly, there should be much more light. 8. All light metals are widely used in all the branches of industry.

Ex. 5. Find the correct answer to the following question:

How does laser light differ from ordinary light?

1. The waves of laser light are found to be coordinated in space and time and to have nearly the same length.

2. The light emitted by an ordinary source consists of uncoordinated waves of many different lengths.

3. Laser light is not so intense and coherent.

4. Laser light does not differ greatly from ordinary light.

Ex. 6. Remember the following antonyms:

internal—external

include—exclude

direct—indirect

dark – light

purity – impurity

Ex. 7. Form the derivatives from the following words:

Differ, purity, use, develop, science, apply.

Ex. 8. Give the missing forms of the following verbs:

light – lighting

find – found

arise-arisen

heat—heating

show—showed

Ex. 9. Open the brackets translating the Ukrainian words into English:

1. The light emitted by an (звичайним) source consists of uncoordinated waves. 2. The scientists found the waves of laser (світла) to be coordinated in (просторі) and time. 3. Laser light is different from ordinary light even when it (просто) illuminates a surface. 4. (За допомогою) some instruments it is possible to examine materials andphysical phenomena in new ways. 5. (Внутрішня) structure should be examined much better.

Ex. 10. Insert prepositions or adverbs:

1. Laser light differs . . . ordinary light. 2. This difference results ... the fact that this light is more intense. 3. . . . means . . . some microscopes we can observe the movement of these particles. 4. This material was examined. . . new ways. 5. He is working . . . the problem of using the source of light in industry. 6. Many new instruments and devices have been built . . this purpose lately. 7. This work consists . . . two parts, the first one having already been done.

The Objective Infinitive Construction

We

expect

him to do it in time

to hear, to see, to watch, to feelь, to observeto notice	I watched her approach. I saw the fire slowly conquered. I see him leave the Institute every day 5 p.m. She hears him speak in the room with the teacher.
to know,to think, to consider, to believe, to suppose, to expect, to imagine, to find, to trust, to assume	I want him to translate the article tomorrow. I expect the students to pass their exams well. We knew them to have finished their work. I want this experiment to be carried out today. He considers this question to be of great importance.
to pronounce,to declare, to report	The surgeon pronounced the wound to be a slight one.
to like,to dislike, to love, to hate	I hate you to talk in this way.
to order, to allow, to permit, to suffer, to have, to make, to have, to get, to force, to cause	She caused a telegram to be sent to him. He makes them clean the laboratory benches when they finish working. Heating caused the body to expand.

Ex. 11. Change the following sentences as in the models:

M оd e 1 I: We expect that they will solve this problem very soon. We expect them to solve this problem very soon.

1. The scientists know that this phenomenon is important. 2. They suppose that she will take part in this work. 3. We consider that he knows the subject well. 4. Chemists know that isotopes find wide application both in industry and agriculture. 5. They expect the reaction will go to completion. 6. We think that he will help us in this work. 7. We consider that mercuric ions are colourless. 8. I want that he will leave for Kyiv tomorrow.

Model II: I thought that he had returned. I thought him to have returned.

1. We knew that the delegation had arrived. 2. They learned that he had carried out the experiment by the end ofthe week. 3. They expected that he had passed his last exam well.

Ex. 12. Translate into English using the Objective Infinitive Construction:

1. Ми знаємо, що промінь лазера широко використовується у медицині. 2. Ми думаємо, що цей експеримент був проведено успішно. 3. Я припускаю, що джерело цього світла буде вивчено. 4. Я хочу, щоб ви взяли участь у цьому дослідженні. 5. Я бачу, як вони проводять досліди в нашій лабораторії. 6. Ми припускаємо, що конференція вже закінчилася. 7. Ми вважаємо, що ці легкі метали будуть використані у багатьох галузях промисловості у майбутньому.

Ex. 13. Translate the following sentences mind the Objective Infinitive Constructions:

1. The scientists stated atoms or molecules, which contain an even number of electrons to have no magnetic moment.2. They found that gas to be oxygen. 3. We supposed thissubstance to have liberated heat when the temperature had been greatly raised. 4. This scientist states laser light to bedifferent from ordinary light. 5. The scientists proved this substance to be an element. 6. After a number of tedious experiments, they made the substance dissolve. 7. Pressure caused ice to melt. 8. The scientists know many substances organic as well as inorganic to be stable in the presence of visible light.

Ex. 14. Translate the text, analyse the infinitives:

How Light is Analysed

The efforts of ancient philosophers to analyse matter begin with an understanding that matter can be separated into its elementary constituents.

The concept that light can be analysed was much less obvious. We know men to have looked at rainbows without devising any kind of rational explanation for them. Even when Rene Descartes noted the colours of a rainbow to be like those produced by a prism he couldn't give an explanation to this phenomenon.

It was Newton, who formulated the basic concept that light from ordinary sources is complex. By "complex" he meant that such light could be analysed into colours and the colours could be used to synthesize light.

Text B

MACHINE-TOOLS