Words to be Learnt. gas-tungsten welding—сварка оплавлением вольфрамовым электродом в среде инертного газа

gas-tungsten welding —сварка оплавлением вольфрамовым электродом в среде инертного газа

inert — инертный

bare — голый

rate [reit] — зд. скорость

gas-metal arc — аргоно-дуговая сварка

surrounding —окружающий

liquid —жидкость, жидкий

droplet —капелька

carbon dioxide —углекислый газ

beneath —под, ниже, внизу

layer —слой

weld seam — сварной шов

semi-automatic — полуавто­матическая

to submerge — погружать

Exercise 4.4. Translate into English:

1. вольфрамовый электрод

2. инертный газ

3. окисление

4. высококачественный сварочный шов

5. скорость сварки

6. аргон, гелий, углекислый газ

7. жидкий металл

8. слой плавкого материала в виде гранул

9. листовой металл

10. полуавтоматические сварочные станки

Exercise 4.5. Translate into Russian:

1. In resistance welding, heat is obtained from the resis­tance of metal to the flow of an electric current.

2. The heat from the arc melts the edges of the metal.

3. A bare electrode is shielded from the air by surround­ing it with argon or carbon dioxide gas.

4. Submerged-arc welding is similar to gas-metal arc welding.

4. Electrodes are clamped on each side of the parts to be welded.

5. Resistance causes heat, which melts the metals and creates the weld.

UNIT V.

MACHINE-TOOLS

Exercise 5.1. Read and translate the text. Answer the questions on the text:

1. What are machine-tools used for?

2. How are most machine-tools driven nowadays?

3. What facilities have all machine-tools?

4. How are the cutting tool and the workpiece cooled during machining?

5. What other machining methods have been developed lately?

6. What systems are used now for the manufacture of a range of products without the use of manual labour?

ТЕХТ A: «MACHINE-TOOLS»

Machine-tools are used to shape metals and other materials. The material to be shaped is called the workpiece. Most machine-tools are now electrically driven. Machine-tools with electrical drive are faster and more accurate than hand tools: they were an important element in the development of mass-production processes, as they allowed individual parts to be made in large numbers so as to be interchangeable.

All machine-tools have facilities for holding both the workpiece and the tool, and for accurately controlling the movement of the cutting tool relatively to the workpiece. Most machining operations generate large amounts of heat, and cooling fluids (usually a mixture of water and oils) must be used for cooling and lubrication.

Machine-tools usually work materials mechanically but other machining methods have been developed lately. They include chemical machining, spark erosion to machine very hard materials to any shape by means of a continuous high-voltage spark (discharge) between an electrode and a workpiece. Other machining methods include drilling using ultrasound, and cutting by means of a laser beam. Numerical control of machine-tools and flexible ma­nufacturing systems have made it possible for complete systems of machine-tools to be used flexibly for the manufacture of a range of products.