- •Unit 5: Metalworking and welding
- •1. Read the text and say what the main metalworking processes are:
- •3. Match the terms with their right definitions.
- •4. Answer the following questions.
- •5. Translate the following sentences from Ukrainian into English using active vocabulary and information from the text to the subject.
- •1. Read the text and say what metal cutting is.
- •4. Find out whether the following statements are true or false.
- •6. Answer the following questions to the text.
- •1. Read the text and say why welding is widely used nowadays.
- •3. Answer the following questions to the text.
- •4. Translate the following sentences from Ukrainian into English.
- •1) Metalworking and metal properties
- •I. Copy the underlined words and word-combinations, translate them into Ukrainian and learn them.
- •III. Answer the following questions.
- •2) Factors affecting machinability
- •I. Copy the underlined words and word-combinations, translate them into Ukrainian and learn them.
- •II. Answer the following questions.
- •3) Metal-Cutting Machines. Lathe
- •I. Copy the underlined words and word-combinations, translate them into Ukrainian and learn them.
- •II. Define whether the following statements are true or false.
- •III. Fill in the following scheme using the text.
- •4) Borys Paton
- •I. Copy the underlined words and word-combinations, translate them into Ukrainian and learn them.
- •III. Give a short summary of the text in English in written or oral form.
- •1. Choose the right variant.
- •2. Change the words in brackets from Ukrainian into English.
- •3. Fill in the right word into the sentences.
- •4. Make up word-combinations with the following words. Translate them into Ukrainian.
3. Answer the following questions to the text.
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 kind of welding can be used for joining steels?
9. What does arc welding require?
10. What is the principle of resistance welding?
4. Translate the following sentences from Ukrainian into English.
1. При контактому зварюванні нагрівання отримують від опору металу потоку електричного струму.
2. Нагрівання від електричної дуги розтоплює краї металу.
3. Електроди затискуються з кожної сторони деталі, яка буде зварюватися.
4. Опір викликає нагрівання, яке плавить метал та створює зварний шов.
5. Зварювання залежить значною мірою від властивостей металу, мети їх використання та наявного обладнання.
6. Зварювання можна поділити на дві групи – зварювання під тиском та зварювання нагріванням.
7. Перевагою газового зварювання є використання портативного обладнання, яке не потребує електричного джерела струму.
8. Електродугове зварювання потребує безперервної подачі електричного струму, щоб створити електричну дугу.
Student independent study:
1) Metalworking and metal properties
An important feature of hot working is that it provides the improvement of mechanical properties of metals. Hot-working (hot-rolling or hot-forging) eliminates porosity, directionality, and segregation that are usually present in metals. Hot-worked products have better ductility and toughness than the unworked casting. During the forging of a bar, the grains of the metal become greatly elongated in the direction of flow. As a result, the toughness of the metal is greatly improved in this direction and weakened in directions transverse to the flow. Good forging makes the flow lines in the finished part oriented so as to lie in the direction of maximum stress when the part is placed in service.
The ability of a metal to resist thinning and fracture during cold-working operations plays an important role in alloy selection. In operations that involve stretching, the best alloys are those which grow stronger with strain (are strain hardening) – for example, the copper-zinc alloy, brass, used for cartridges and the aluminum-magnesium alloys in beverage cans, which exhibit greater strain hardening.
Fracture of the workpiece during forming can result from inner flaws in the metal. These flaws often consist of nonmetallic inclusions such as oxides or sulfides that are trapped in the metal during refining. Such inclusions can be avoided by proper manufacturing procedures.
The ability of different metals to undergo strain varies. The change of the shape after one forming operation is often limited by the tensile ductility of the metal. Metals such as copper and aluminum are more ductile in such operations than other metals.