Text в: «other types of welding»

Non-consumable Electrode Arc welding

As a non-consumable electrodes tungsten or carbon electrodes can be used. In gas-tungsten arc welding a tungsten electrode is used in place of the metal electrode used in shielded metal-arc welding. A chemically inert gas, such as argon, helium, or carbon dioxide is used to shield the metal from oxidation. The heat from the arc formed between the electrode and the metal melts the edges of the metal. Metal for the weld may be added by placing a bare wire in the arc or the point of the weld. This process can be used with nearly all metals and pro­duces a high-quality weld. However, the rate of welding is considerably slower than in other processes.

Gas-Metal Arc

In gas-metal welding, a bare electrode is shielded from the air by surrounding it with argon or carbon dioxide gas and sometimes by coating the electrode with flux. The electrode is fed into the electric arc, and melts off in droplets that enter the liquid metal of the weld seam. Most metals can be joined by this process.

Submerged Arc

Submerged-arc welding is similar to gas-metal arc welding, but in this process no gas is used to shield the weld. Instead of that, the arc and tip of the wire are sub­merged beneath a layer of granular, fusible material that covers the weld seam. This process is also called electroslag welding. It is very efficient but can be used only with steels.

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.

Vocabulary

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

inert — инертный

edge — край

bare — голый

rate — зд. скорость

gas-metal arc — аргонодуговая сварка

considerably — значительно, гораздо

surrounding — окружающий

carbon dioxide — углекислый газ

droplet — капелька

liquid — жидкость, жидкий

beneath — под, ниже, внизу

layer — слой

weld seam — сварной шов

resistance — сопротивление

clamp — зажим, зажимать

sheet — лист

fusible — плавкий

granular — плавкий

semi-automatic — полуавтомати­ческая

to create — создавать

to submerge — погружать

General understanding:

1. What is the difference between the arc-welding and non-consumable electrode arc welding?

2. What are the disadvantages of the non-consumable electrode arc welding?

3. How is electrode protected from the air in gas-metal arc welding?

4. What is submerged arc welding?

5. What is the principle of resistance welding?

6. Where is semi-automatic welding employed?

Exercise 6.2. 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. полувтоматические сварочные станки

Exercise 6.3. 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.

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

6. Resistance causes heat which melts the metals and creates the weld.

FAMOUS PEOPLE OF SCIENCE AND TECHNOLOGY

James Prescott Joule, famous British physicist, was born in 1818 in Salford, England.

Joule was one of the most outstanding physicists of his time. He is best known for his research in electricity and thermodynamics. In the course of his investigations of the heat emitted in an electrical circuit, he formulated the law, now known as Joule's law of electric heating. This law states that the amount of heat produced each second in a conductor by electric current is proportional to the resistance of the conductor and to the square of the current. Joule experimentally verified the law of con­servation of energy in his study of the conversion of me­chanical energy into heat energy.

Joule determined the numerical relation between heat and mechanical energy, or the mechanical equivalent of heat, using many independent methods. The unit of en­ergy, called the joule, is named after him. It is equal to 1 watt-second. Together with the physicist William Thomson (Baron Kelvin), Joule found that the tempera­ture of a gas falls when it expands without doing any work. This phenomenon, which became known as the Joule-Thomson effect, lies in the operation of modern refrigeration and air-conditioning systems.

UNIT 7

AUTOMATION AND ROBOTICS

I. Text A: «Automation», Text B: «Types of automation»,

Text C: «Robots In manufacturing»

II. Famous people of science and technology: James Watt.

Text A: «AUTOMATION»

Automation is the system of manufacture perform­ing certain tasks, previously done by people, by machines only. The sequences of operations are controlled auto­matically. The most familiar example of a highly auto­mated system is an assembly plant for automobiles or other complex products.

The term automation is also used to describe non-manufacturing systems in which automatic devices can op­erate independently of human control. Such devices as automatic pilots, automatic telephone equipment and automated control systems are used to perform various operations much faster and better than could be done by people.

Automated manufacturing had several steps in its development. Mechanization was the first step necessary in the development of automation. The simplification of work made it possible to design and build machines that resembled the motions of the worker. These specialized machines were motorized and they had better production efficiency.

Industrial robots, originally designed only to perform simple tasks in environments dangerous to human work­ers, are now widely used to transfer, manipulate, and position both light and heavy workpieces performing all the functions of a transfer machine.

In the 1920s the automobile industry for the first time used an integrated system of production. This method of production was adopted by most car manufacturers and became known as Detroit automation.

The feedback principle is used in all automatic-con­trol mechanisms when machines have ability to correct themselves. The feedback principle has been used for centuries. An outstanding early example is the flyball governor, invented in 1788 by James Watt to control the speed of the steam engine. The common household ther­mostat is another example of a feedback device.

Using feedback devices, machines can start, stop, speed up, slow down, count, inspect, test, compare, and measure. These operations are commonly applied to a wide variety of production operations.

Computers have greatly facilitated the use of feedback in manufacturing processes. Computers gave rise to the development of numerically controlled machines. The motions of these machines are controlled by punched paper or magnetic tapes. In numerically controlled ma­chining centres machine tools can perform several dif­ferent machining operations.

More recently, the introduction of microprocessors and computers have made possible the development of computer-aided design and computer-aided manufacture (CAD and CAM) technologies. When using these systems a designer draws a part and indicates its dimensions with the help of a mouse, light pen, or other input device. Af­ter the drawing has been completed the computer automatically gives the instructions that direct a machining centre to machine the part.

Another development using automation are the flex­ible manufacturing systems (FMS). A computer in FMS can be used to monitor and control the operation of the whole factory.

Automation has also had an influence on the areas of the economy other than manufacturing. Small comput­ers are used in systems called word processors, which are rapidly becoming a standard part of the modern office. They are used to edit texts, to type letters and so on.

Automation in Industry

Many industries are highly automated or use automa­tion technology in some part of their operation. In com­munications and especially in the telephone industry dialing and transmission are all done automatically. Rail­ways are also controlled by automatic signaling devices, which have sensors that detect carriages passing a par­ticular point. In this way the movement and location of trains can be monitored.

Not all industries require the same degree of automa­tion. Sales, agriculture, and some service industries are difficult to automate, though agriculture industry may become more mechanized, especially in the processing and packaging of foods.

The automation technology in manufacturing and as­sembly is widely used in car and other consumer product industries.

Nevertheless, each industry has its own concept of automation that answers its particular production needs.

Vocabulary:

automation — автоматизация

previously — ранее

sequence — последовательность

assembly plant — сборочный завод

non-manufacturing — непроизводственный

device — устройство, прибор

resemble — походить

efficiency — эффективность

flyball governor — центробежный регулятор

steam engine — паровоз

household thermostat — бытовой термостат

facilitate — способствовать

punched — перфорированный

aid — помощь

dimension — измерение, размеры

General understanding:

1. How is the term automation defined in the text?

2. What is the most «familiar example» of automation given in the text?

3. What was the first step in the development of automaton?

4. What were the first robots originally designed for?

5. What was the first industry to adopt the new integrated system of production?

6. What is feedback principle?

7. What do the abbreviations CAM and CAD stand for?

8. What is FMS?

9. What industries use automation technologies?

Exercise 7.1. Find the following words and word combinations in the text:

1. автоматические устройства

2. автоматизированное производство

3. выполнять простые задачи

4. как легкие, так и тяжелые детали

5. интегрированная система производства

6. принцип обратной связи

7. механизм может разгоняться и тормозить

8. компьютер автоматически посылает команды

9. высокоавтоматизированная система

10. непроизводственная система