Методичка по сварке (Методичка для МТ7)

Unit 1. Weld joints. Parts of a joint.

Preview. In this unit you will study different types of weld joints, ways of edge preparation and standard terms for the description of parts of a joint.

Warming – up.

1. Match the words in A with the definitions in B.

A	B
1. A lap joint	a. A joinery technique in which two members are joined by simply butting them together.
2. A butt joint	b. A joinery technique in which two members are located at right angles to each other.
3. An edge joint	c. A joinery technique used to join the edges of two or more members lying in the same plane.
4. Corner and tee joints	d. A joinery technique used to produce a joint by overlapping two ends or edges.

1.2 Before you start reading the text try to answer the following questions:

1. What parameters are welds classified by? 2. What types of welds do you know? 3. How can joints be subdivided within these types? 4. What does the choice of weld depend on?

1.3 Look through the text and grasp the general idea.

Weld joints. (3219п. зн.)

The weld joint is where two or more metal parts are joined by welding. Welds can be geometrically prepared in many different ways. The five basic types of weld joints are the butt, corner, tee, lap, and edge. Other variations exist as well—for example, double-V preparation joints are characterized by the two pieces of material, each tapering to a single centre point at one-half their height. Single-U and double-U preparation joints are also fairly common—instead of having straight edges like the single-V and double-V preparation joints, they are curved, forming the shape of a U. Lap joints are also commonly more than two pieces thick—depending on the process used and the thickness of the material, many pieces can be welded together in a lap joint geometry.

A butt joint is used to join two members aligned in the same plane. This joint is frequently used in plate, sheet metal, and pipe work. A joint of this type may be either square or grooved.  

Corner and tee joints are used to join two members located at right angles to each other. In cross section, the corner joint forms an L-shape, and the tee joint has the shape of the letter T.

Various joint designs of both types have uses in many types of metal structures. A lap joint, as the name implies, is made by lapping one piece of metal over another. This is one of the strongest types of joints available; however, for maximum joint efficiency, you should overlap the metals a minimum of three times the thickness of the thinnest member you are joining. Lap joints are commonly used with torch brazing and spot welding applications. An edge joint is used to join the edges of two or more members lying in the same plane.  In most cases, one of the members is flanged.  While this type of joint has some applications in platework, it is more frequently used in sheet metal work.  An edge joint should only be used for joining metals 1/4 inch or less in thickness that are not subjected to heavy loads.

Often, particular joint designs are used exclusively or almost exclusively by certain welding processes. For example, resistance spot welding, laser beam welding, and electron beam welding are most frequently performed on lap joints. However, some welding methods, like shielded metal arc welding, are extremely versatile and can weld virtually any type of joint. Additionally, some processes can be used to make multipass welds, in which one weld is allowed to cool, and then another weld is performed on top of it. This allows for the welding of thick sections arranged in a single-V preparation joint, for example. The type of joint selected for any welding job may materially affect the quality and strength of the weld; the cost of labour and materials; the time and expense involved in preparing, jigging, and positioning the work; and other factors of like importance. The selection of the proper joint type depends on a number of factors, such as joint thickness and material, desired physical properties in the finished joint, size of the pieces being welded, accessibility of the joint, fit-up obtainable, available edge preparation equipment, number of pieces to be welded, and specifications of regulatory codes (if applicable).

From http://64.78.42.182/sweethaven/BldgConst/Welding/lessonmain.asp?lesNum=3&modNum=2)

1.4 Terminological vocabulary to the text “Weld joints.”Try to memorize the following words and word combinations.

1. a weld, n - сварной шов;

2. to be subjected to heavy loads – подвергаться большим нагрузкам;

3. to taper[6teipQ],v – сходить на конус, сужаться;

4. a preparation joint – подготовленное соединение под сварку;

5. to curve[kBv], v – изгибаться;

6. a right angle – прямой угол;

7. a cross  section – поперечное сечение;

8. a multipass weld – многопроходный шов;

9. the finished joint – чистовой шов;

10. applicable [ 0AplikQbl] , adj – применимый, пригодный;

11. accessibility [ Qk4sesi0bilQti] , n – доступность, удобство осмотра и обслуживания;

12. to fit-up, v – сборка соединения под сварку;

13. positioning [pQ0ziS(Q)niN], n – установка в удобном для сварки положении;

Word study.

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

Geometrically, frequently, to characterize, various, structure, however, quality, to arrange, physical, strength, applicable, accessibility, to affect, angle, virtually, regulatory, jigging, particular, height.

1.6 Read the text again and find the correct endings for the phrases below.

1. Double-V preparation joints are characterized

a) by the two pieces of material each tapering to a single centre point at one-half their width;

b) by the two pieces of material each tapering to a single centre point at one-third their height;

1. by the two pieces of material not tapering to a single centre point at one-half their height;

2. by the two pieces of material each tapering to a single centre point at one-half their height.

1. A butt joint is used

a) to join two members located at right angles to each other;

b) to join two members aligned in the same plane;

c) to join two members by lapping one piece of metal over another;

d) to join the edges of two or more members lying in the same plane.

3. When making up a lap joint, for maximum joint efficiency

1. you should overlap the metals a minimum of three times the thickness of the thickest member you are joining;

2. you should overlap the metals a minimum of four times the thickness of the thinnest member you are joining;

3. you should overlap the metals a minimum of three times the thickness of the thinnest member you are joining;

4. you should overlap the metals not more than three times the thickness of the thinnest member you are joining.

4. An  edge  joint  should  only  be  used  

1. for  joining metals one forth inch or less in thickness that are not subjected to heavy loads;

2. for  joining metals one forth inch or more in thickness that are not subjected to heavy loads;

3. for  joining metals one forth inch or less in thickness that are subjected to heavy loads;

4. for joining metals one fifth inch or less in thickness that are not subjected to heavy loads.

5. Resistance spot welding

a) is most frequently performed on edge joints;

b) is most frequently performed on lap joints;

c) is less frequently performed on lap joints;

d) is most rarely performed on lap joints.

6. Shielded metal arc welding

1. can weld only joints that are not subjected to heavy loads;

2. is not versatile and can weld virtually only one type of joint ;

c) is most frequently performed on lap joints;

d) is extremely versatile and can weld virtually any type of joint.

7. In cross section, the corner joint forms  

1. an L-shape; b) a T-shape; c) a U-shape; d) a V-shape.

8. What is one of the strongest types of joints available?

a) a butt joint; b) a lap joint; c) an edge joint; d) a corner joint.

1. . The selection of the proper joint type doesn’t depend on

a) the joint thickness and material; b)the number of pieces to be welded;

c) the accessibility of the joint; d)the type of testing.

1. Some processes are most frequently performed on lap joints. Choose the odd one out.

1. resistance spot welding; b) electron beam welding ;

c) the electrogas welding; d) laser beam welding.

1.7 Find in the text the English equivalents for the following phrases.

другие варианты также существуют; вместо прямолинейных кромок; в зависимости от используемого процесса; как гласит название; применяются в обоих видах металлических конструкций; в 3 раза превышая толщину самого тонкого элемента; один из элементов делается с отбортовкой; под прямым углом друг к другу; которые не подвержены большим нагрузкам; даётся возможность охладиться; это позволяет производить сварку; больших сечений; и других столь же важных факторов; количество деталей, которые необходимо сварить.

1.8 Fill in the gaps with the necessary prepositions.

1. The weld joint is where two or more metal parts are joined … welding.	a) in
2. An edge joint should only be used … joining metals 1/4 inch or less in thickness.	b) of
3. Lap joints are commonly used … torch brazing and spot welding applications.	c) on
4. A joint of this type may be … square or grooved.	d) by
5. Welds can be geometrically prepared … many different ways.	e) over
6. A lap joint is made by lapping one piece of metal … another	f)  for
7. Corner joints are used to join two members located … right angles to each other.	g) either
8. Instead … having straight edges single-U and double-U preparation joints are curved, forming the shape of a U.	h) to
9. Many pieces can be welded together in a lap joint geometry depending … the process used and the thickness of the material.	i) with
10. Double-V preparation joints are characterized by the two pieces of material each tapering … a single centre point	j) at

1.9 Translate the following word combinations into Russian.

Two or more metal parts; the five basic types of weld; double-V preparation joints; the two pieces of material each tapering to a single centre point; two members located at right angles to each other; the edges of two or more members lying in the same plane; one piece of metal; sheet metal work; metals ¼ inch or less in thickness; thick sections arranged in a single-V preparation joint; the type of joint selected for any welding job; the pieces being welded; fit-up obtainable; available edge preparation equipment; available edge preparation equipment; a number of pieces to be welded.

1.10 Make up a summary in English to the text “Weld joints”.