Методичка по сварке (778485), страница 3

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From (http://en.wikipedia.org/wiki/Welding#_note-27#_note-27)

1.21 Terminological vocabulary to the text “Heat-affected zone”. Try to

memorize the following words and word combinations.

1. a heat-affected zone – зона термического влияния;

2. to alter [0OltQ], v – меняться;

3. heat input – ввод тепла;

4. an intermittent weld – прерывистый шов;

5. to surround, v – окружать;

6. detrimental [4detri0ment(Q)l], adj – вредный, пагубный;

7. thermal diffusivity – теплопроводность, коэффициент теплопроводности;

8. conversely [0konvBsli], adv – обратно, противоположно, наоборот;

9. to result in, v – привести к…;

10. voltage [0voltidG], n – электрическое напряжение;

11. current [0kqr(Q)nt], n – электрический ток;

12. a value [0vAlju], n – значение.

Word Study

1.22 Read the words correctly. Consult the dictionary if necessary.

to minimize, procedure, formula, technique, to vary, diffusivity, to inject, voltage.

1.23 Translate the following sentences into Russian paying attention to the words underlined :

1. One technique often used to minimize heat input is the intermittent weld. 2. The

effects of welding on the material surrounding the weld can be detrimental —depending on the materials used and the heat input of the welding process used. 3. The welder must also carefully add filler metal at the proper times doing manual GTAW. 4. Gas tungsten arc welding is a process used to produce high-quality welds in virtually all weldable metals. 5. Having initiated the arc between the welding electrode and the base metal, the welder controls correct arc length.

6. The electrodes on small spot welders, used to weld thin materials, may be air-cooled. 7. The welding machine electrodes are flat plates called platens. 8. This causes the materials being joined to vibrate at a corre­sponding rate. 9. A coupling system transmits the mechanical vibration to the welding tip and thus into the metals being joined. 10. The pressure used is less and the welding time is shorter, than those used in resistance welding. 11. Aluminum welded by the cold welding has a tensile strength of up to 152MPa.

1.24 Translate the following sentences into Russian paying attention to the underlined words :

1. In the picture you can see the HAZ of a pipe weld, with the blue area being the metal most affected by the heat. 2. Arc welding falls between these two extremes, with the individual processes varying somewhat in heat input. 3. The efficiency is dependent on the welding process used, with shielded metal arc welding having a value of 0.75. 4. Double-V preparation joints are characterized by the two pieces of material, each tapering to a single centre point at one-half their height. 5. This type of joint having some applications in platework, it is more frequently used in sheet metal work. 6. The HAZ includes the portion of the base metal that has not been melted, the structural or mechanical properties of the metal having been altered by the welding heat. 7. The diffusivity being high, the material cooling rate is high and the HAZ is relatively small. 8. Many variations of joints being used, the parts of the joint are described by standard terms. 9. The heat of the electric arc being controlled by the current setting and by the arc length, electrode diameter and flux material will determine the type (ac or dc) and amount of welding current required. 10. With the tungsten electrode being not consumed, it does not melt and enter the weld.

1.25 Match the two halves of the sentence fragments to make logical statements.

1.26 Translate the following text from Russian into English. (656 п. зн.)

Правильная разделка кромок свариваемых деталей обеспечивает качественный и полный провар. В тексте были приведены наиболее часто применяемые формы разделки кромок листов для получения одностороннего шва. Сочетание минимального зазора между наклонными кромками свариваемых листов и угла между этими двумя наклонными кромками должно выбираться таким образом, чтобы обеспечивалось равномерное и полное проваривание до корня шва. Оптимальная комбинация заданных параметров определяется большим числом факторов. Слишком малый зазор и малый угол могут не обеспечить полный провар. Неправильное сочетание ширины и глубины шва приводит к образованию трещин в шве.

1.27 Answer the following questions.

1. What are the five basic types of weld joints? 2. Can you define a butt joint? an edge joint? a lap joint? corner and tee joints? 3. Where are they mainly used? 4. What does the type of joint selected for any welding job affect? 5. What is a multipass weld? 6. What factors influence the selection of the proper joint type? 7. What configuration can a root have? 8. How can the bevel angle and the groove angle be compared? 9. What is a groove radius? 10. How is the root penetration measured? 11. What zone is interesting for the welder? 12. Why does a welder have to control the heat input? 13. Why can the effects of welding on the material surrounding the weld be detrimental? 14. How does the thermal diffusivity of the base material influence the HAZ? 15. Can you classify the welding processes according to the size of the HAZ?

1.28 Make up and practice short situations using the following words and word combinations.

1. can be geometrically prepared, basic types of weld joints, aligned in the same plane, at right angles to each other, for maximum joint efficiency, of two or more members lying in the same plane.;

2. are most frequently performed, any type of joint, to make multipass welds, may materially affect, the quality and strength of the weld;

3. the parts of the joint, closest to each other, viewed in cross section, an opening or space;

4. the HAZ, has not been melted, the structural or mechanical properties, the intermittent weld, the blue area;

5. can be detrimental, varying size and strength, the thermal diffusivity of the base material, the amount of heat injected;

1.29 Make up dialogues using the word expressions of Ex. 8.28

Writing

1.30 Read the text and translate it in written form.

Welding Positions (1938 п. зн.)

The importance of welding in the flat position whenever possible cannot be stressed too strongly. The quality of the weld is better, the operation easier and faster. However, occasions will arise when it is necessary to work on parts fixed in position under which condition welds must be deposited horizontally, vertically and overhead. It must be realized at the very beginning that welding in these positions is difficult and will require constant practice to develop skill.

As in the case of welding in the flat position, it is best to start practicing by first running bead welds in the various positions. Then as facility is gained on these operations practice may be continued on butt and fillet welds (tee and lap joints) in these positions.

One of the first facts noted when welding in these positions is that the force of gravity tends to cause the molten metal to drip (fall) down. The technique used, therefore must be designed to overcome this and since it is difficult it is best to approach this by steps. To accomplish this, start by making horizontal bead welds on plates inclined at 45 degrees. When this has been mastered so that uniform beads can be made consistently, practice on welding vertically may be started. Again begin with an easy operation such as running beads vertically on plates set at 45 degrees.

To progress with this practice it is necessary now to move the plates into vertical position. Welding vertically may be performed either by carrying the weld upward or starting from the top and welding down. It is generally conceded that working upward is easier and therefore, bead welds in this manner should be practiced. Since bead welds are of limited practical value, this experience must be extended by practicing on butt welds in the vertical and horizontal patterns.

In use, the beveled plate edges should be spaced on the backing strip and the strip tack welded to the plates on the reverse side.

From (http://www.key-to-steel.com/default.aspx?ID=CheckArticle&LN=RU&NM=192)

Unit 2. Butt Joint Welds.

Preview. In this unit you will get more detailed information about butt joints.

Warming-up

2.1 Before reading the texts of the Unit “Butt Joint Welds” try to answer the following questions:

1. What types of butt joints can you name?

2. Is the choice of the type dependant on the material thicknesses?

3. What are the applications of each type?

2.2 Match the words in column A with their definitions in column B:

A B

2.3 In pairs/groups discuss the following:

What type of butt joint weld would you choose to:

- weld parts less than 5/16-inch thick;

- weld parts more than 5/16-inch thick;

- get multipass submerged arc welds;

- two-pass submerged arc welds.

2.4 Read the text making paying attention to the active terminological vocabulary to check if your predictions were correct.

Характеристики

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