Exercises. I. Use the following words and phrases in sentences of your own:

I. Use the following words and phrases in sentences of your own:

electrode, to weld, fusion, non-detachable joining, electric resistance welding, to ignite, iron oxide, arc welding, spot welding, torch, velocity, autogenous welding, to generate, current

II. Answer the following questions:

1. What is welding and what is it used for? 2. What types of welding do you know? 3. What is the source of heat for arc welding? 4. What is the source of heat for gas welding? 5. What gas is used in autogenous welding? 6. What methods of autogenous welding do you know? 7. What is spot welding? 8. What is butt welding used for? 9. What is hammer welding? 10. What does the selection of a given type of welding depend on? 11. What processes does resistance welding embrace?

III. Supply synonyms for the following words:

burner, to fuse, various, to get, to convert, ahead of, to utilize

IV. Underline the suffixes in the following words and state what part of speech they belong to:

detachable, fusion, mechanical, pressure, obtained, finely, resistance, molten, rightward, agricultural, implement, suitable, possibility

V. Give derivatives from the following words and translate them into Russian:

to obtain, chemistry, final, to achieve, to conduct, electrical, external, press, wide

VI. Change the following sentences using the subordinate clauses instead of participle and gerundial constructions and translate the following sentences into Russian:

Example: 1. Having fused two metal pieces we obtained a weld.

When we have fused two metal pieces we obtained a weld.

2. We heard of their having applied a new kind of additive to obtain firm joining.

We heard that they have applied a new kind of additive to obtain firm joining.

1. After having heated two metal pieces in a blacksmith's forge they reached their plastic stage. 2. Having heated the additive to its melting temperature it began to diffuse into the metals to be joined. 3. We heard of their having applied termite welding to provide a non-detachable joining of two like metal pieces. 4. The engineer informed them of the hammer welding of two metal pieces having been completed. 5. We know of Petrov's having invented the electric arc. 6. Having been asked to join these rods by butt welding, I had to prepare my instruments for this work. 7. Having found a new method of welding, we were able to join machine parts better and faster.

VII. Give English equivalents of the following words:

сварка встык, контактная сварка, термитная сварка, сплавлять, шов, соединение, выбор, электрод, ток, площадь, присадочный материал, зажигать, ремонтировать, газосмешивающая камера, затвердевать, остывать, скорость, пламя

VIII. Giving answers to the following questions describe the process of electric arc melding shown in Fig. 32:

1. What process is shown in Fig. 32? 2. How can an electric circuit be established in electric arc welding? 3. When is an electric arc created? 4. Where is the electrical energy converted into heat? 5. What is an additive? 6. Where is an additive to be placed? 7. What is melted by the electric arc? 8. When does the molten metal cool, solidify and form a weld, joining the parts of the work?

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