Итоговое занятие по теме "Types of Welding"

Types of welding.

1. Read and translate the texts and match the titles to the texts.

1. Shielded Metal Arc welding

2. Submerged Arc welding

3. Gas-Metal Arc welding

4. Non-consumable Electrode Arc welding

1. 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.

2. In shielded metal-arc welding, a metallic electrode, which conducts electricity, is coated with flux and connected to a source of electric current. The metal to be welded is connected to the other end of the same source of current. An electric arc is formed by touching the tip of the electrode to the metal and then drawing it away. The intense heat of the arc melts both parts to be welded and the point of the metal electrode, which supplies filler metal for the weld. This process is used mainly for welding steels.

3. 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.

4. 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 electro slag welding. It is very efficient but can be used only with steels.

Vocabulary

tungsten electrodes вольфрамовые электроды

droplet капля

carbon dioxide углекислый газ

laver слой

weld seam сварной шов

semi-automatic полуавтоматический

to submerge погружать

liquid metal жидкий метал

2. Answer the questions.

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?

3. Find in the text.

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

4. 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.

WELDING

1. Welding is a process of joining together metallic parts by heating the place of contact to the fusion state.

Welding processes are classified according to the source of energy employed for heating, the metals and the state of the metal at the place of welding.

2. There are different types of welding such as hammer welding, thermit welding, electric arc welding, gas welding, etc.

3. Hammer welding is a process in which two heated metal parts are joined and fused together by force from a power hammer.

4. Thermit welding is a process consisting of a chemical reaction. It is used in repairing large sections such as rails, frames, etc.

5. Resistance welding process forms a whole group consisting of many types of welding such as spot welding, butt welding and others.

6. In arc welding the workpieces are not melted by flame. They are melted by an electric arc. In order to create the arc, a powerful electric current must be provided. The current must be at least 60 A, otherwise the arc will not create enough heat.

7. In gas welding, it is necessary to use a mixture of two gases. To create a hot flame, a combustible gas must be mixed with oxygen.

Gas welding is normally used to join steel to steel.

2. Translate into Russian in writing paragraphs 1, 4, 6, 7. (Переведите на русский язык в письменной форме абзацы 1, 4, 6, 7.)

3. Find the right column of Russian equivalents of English words and phrases. (Найдите в правой колонке русские эквиваленты английских слов и словосочетаний):

4. Find appropriate answers to the questions and write them in the order in which the questions are asked. (Найдите соответствующие ответы на вопросы и напишите их в той последовательности, в которой заданы вопросы):

5. Complete the sentences by selecting the appropriate option end. (Закончите предложения, выбрав соответствующий вариант окончания):