Методичка по сварке (778485), страница 7

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3.12 Before reading the text below translate the following sentences paying attention to the infinitives underlined:

1. The parts to be welded are placed together with the outside edge melted. 2. The method to be applied is fast and reliable, but tends to make extremely weak joints. 3. The top piece to be placed is thin enough compared with the bottom piece. 4. This type of welds tends to make extremely weak joints due to the stress angles to be caused by a flange. 5. The edges of the plates to be welded by corner joints may be machined prior to welding. 6. The method to be chosen for welding the pieces depends upon the material, configuration and other reasons. 7. T- joints occur when the members to be welded come together at right angles. 8. A root face is a portion of the prepared edge of a part to be joined by a groove weld. 9. Friction welding is a process to be applied where a sufficient volume of similar parts is provided because of the initial expense for equipment and tooling. 10. The new technology is widely approved because of its effectiveness and the possibility of the equipment to be adjusted for the new process easily.

3.13 Before reading the text try to recollect what other types of joints you know.

Other Types of Joints (2700) Part 1

Edge Joints

Edge joints are often used when the members to be welded will not be subjected to great stresses. Edge joints are not recommended where impact or great stress may occur to one or both of the welded members. An edge joint occurs when the edges of parallel or nearly parallel members meet and are joined by a weld. If required, the joints can be altered by grinding, cutting or machining the edges into a groove. The groove can be a square, beveled, V, J, or U. The main purpose of the groove is to allow proper penetration or depth of fusion. Complete joint penetration refers to weld metal that extends completely through the groove and has complete fusion into the base metal.

Lap joints

Another joint design used a great deal in the welding industry is the lap joint. In order to weld two overlapping pieces of metal, the lap joint is used by means of connecting fillet, plug, slot, spot, projection, or seam welds. A single lap joint is welded from one side; however a single lap joint welded from two sides has a greater strength. The lap joint is the most common joint used in welding, since they are most applicable in welding thin materials.

A lap joint has good mechanical properties, especially when welded on both sides. The type of weld used on a lap joint is generally a fillet weld. If a groove weld is called for, it can be applied with a single or double bevel. The groove weld may or may not be followed with a fillet weld. The degree of overlap of the members is generally determined by the thickness of plate. In other words, the thicker the plate, the more overlap is required.

Fillet Welds

Fillet welds are approximately triangular in cross sectional shape and are made on

members whose surfaces or edges are approximately 90° to each other. Fillet welds

can be as strong, or stronger than the base metal if the weld is the correct size and

the proper welding techniques are used. When discussing the size of fillet welds,

weld contour must first be determined. Contour is the shape of the face of the weld.

There are three types of fillet weld contours: flat, convex, and concave depending

upon a cross section profile.

T-Joints

A T-joint occurs when the surfaces of two members come together at

approximately right angles, or 90°, and take the shape of a "T". On this particular

type of joint, a fillet weld is used. T-joints possess good mechanical strength,

especially when welded from both sides. They generally require little or no joint

preparation and are easily welded when the correct parameters are used. The edges

of the T-joint may be left square if only a fillet weld is required. For groove welding they may be altered by thermal cutting, machining or grinding.

from: Joining Technologies | Newgate International Business Center | (slightly abridged)

3.14 Terminological vocabulary to the text “Other Types of Joints. Part 1”.

Try to memorize the following words and word combinations.

1. an edge joint - стыковое соединение

2. grinding [0graindiN], n. - шлифование

3. machining, n. -обработка (на станке)

4. a Т- joint, tee joint — тавровое соединение

5. a fillet weld — сварной шов угловой

6. a lap joint - соединение внахлестку

7. to overlap, v. - перекрывать, частично покрывать, заходить один на другой

8. a fillet, n - кромка, желобок, углубление

9. a plug [plqg], n - пробка, заглушка, втулка

10. a slot, n- щель, прорезь

11. a spot, n - небольшой участок, пятнышко

12. a projection, n - выступ, выступающая часть

13. a seam weld - роликовый шов

14. to call for, v - требовать

15. flat, adj - плоский

16. convex [4kon0vex], adj - выпуклый

17. concave [koN0keiv], adj - вогнутый

3.15 In pairs discuss mechanical properties of each type of joints.

3.16 Make up and practise short situations with the following words and word combinations:

1. corner joint, four sub types, low energy density welder, high energy density
   welder

2. edge joints, subjected to great stresses, groove, penetration or depth of fusion

3. t-joint, right angle, fillet weld, little or no joint preparation

4. lap joint, good mechanical properties, single or double bevel, thickness of the
   plate

5. fillet weld, triangular shape, base material, cross section profile

3.17 Make up questions with the words and word combinations from the previous exercise, and ask your partner.

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

Быть подверженным большим напряжениям, сделать возможным необходимое проплавление, широко используемый, требуется стыковой шов, односторонний скос кромки, двойной скос кромки; чем толще пластина, тем больше требуется нахлест, в зависимости от профиля поперечного сечения, элементы соединяются под приблизительно прямым углом, приобретают форму буквы T.

3.19 Define key words for each paragraph of the text“Other Types of Joints. Part 1”.

3. 20 Using the key words defined in the previous exercise shortly describe each type of joints.

3.21 Translate the first paragraph of the following text in written form without using a dictionary.

3.22 Scan the whole text and find additional information about T-joints compared to the information from the text above. Work with a partner.

Other Types of Joints. Part 2. T-joints (2350)

Tee joints are used when one part must be joined to the center of another part forming a "T". Like the other types of weld, there are several ways that this joint can be prepared and welded, each with their own benefits and disadvantages. Most methods of welding tee joints involve welding the two joints between the parts, with either a high or low energy density beam. Like the other weld types, there are fundamental differences in the processes used with these two types of weld. When a tee joint is welded with either a high or low energy density system, the process usually involves first placing and clamping (clamp - скреплять) the parts

in the necessary configuration. If necessary, the parts may be tack welded (tack weld - соединять прихваточным швом) together to make welding the final joint easer. This can, however, case complications in the final weld, which will be elaborated (elaborate - тщательно обработать) on later.

In the case of low energy density welding, the joint is made by making a weld bead on one, or usually both, sides of the vertical plate. This is usually done with filler wire, and forms a very strong weld, usually with minimal distortion. However, it is not nearly as strong as the base metal. In this case, there are relatively few problems associated with spot welding before the final weld.

There are more options for welding tee joints with high energy density devices, such as the laser and electron beam. One option is to weld in a manner similar to that used in low energy density processes, along the joint. However, rather than simply welding on the surface, the beam penetrates deep into the piece, making a weld that can be comparable in strength to the base metal, Unfortunately, this method tends to case more distortion of the workpiece than low energy density methods. Welding both sides of the joint can help to correct this distortion, as well as strengthen the weld.

The second option when welding tee joints with a high energy density beam is to weld through the top of the "T" and into the perpendicular. This can be faster and easer, as it does not require that the joint be followed exactly, but tends to be far weaker than a weld from the side. This method also reduces distortion and is particularly well suited for welding a relatively thick piece to a thin plate, as the beam easily melts the thin plate that it must weld through but does not heat the second plate excessively.

from: Joining Technologies | Newgate International Business Center | (slightly abridged)

3.23 Make up 3-4 questions to the text and ask them your partner.

3.24 Project work. Search Internet study magazine articles. Find the information about types of joints for composite and other new materials. Make presentations in PowerPoint.

3.25 Read the following text and translate it using the terminological vocabulary.

В зависимости от взаимного расположения свариваемых деталей различают следующие сварные соединения: стыковые, угловые, торцевые, внахлестку и тавровые.
Стыковые соединения являются наиболее распространенным типом соединений при газовой сварке. При сварке металла толщиной до 2 мм применяют соединение в стык с отбортовкой кромок, выполняемое без присадочного металла, или соединение в стык без разделки кромок с применением присадочной проволоки. При толщине металла 2—5 мм стыковые соединения выполняют без разделки кромок с зазором между свариваемыми концами. Сваривая металлы толщиной более 5 мм, применяют стыковое соединение с V -образной или Х-образной разделкой кромок.

Угловые и торцевые соединения также часто применяются при сварке металлов малой толщины. Торцевые соединения обычно выполняются без присадочного металла, и шов образуется за счет расплавления кромок основного металла.

Соединения внахлестку и тавровые можно применять при сварке деталей малой толщины. При сварке деталей толщиной больше 3—4 мм соединения этого типа нежелательны, так как они требуют более продолжительного нагрева металла при сварке, что приводит к короблению свариваемого изделия или образованию трещин.

Сварные швы по виду разделяются на стыковые и угловые. Стыковой шов располагается между кромками основного металла. Соединения внахлестку и тавровые выполняются угловыми швами. Угловой шов накладывается на поверхность свариваемых частей металла.

Writing

3.26 Read the following text and translate it in written form.

A tack weld is a weld made to hold parts of an assembly in proper alignment temporarily until the final welds are made. Although the sizes of tack welds are not specified, they are normally between 1/2 inch to 3/4 inch in length, but never more than 1 inch in length. In determining the size and number of tack welds for a specific job, you should consider thicknesses of the metals being joined and the complexity of the object being assembled. Plug and slot welds are welds made through holes or slots in one member of a lap joint. These welds are used to join that member to the surface of another member that has been exposed through hole. The hole may or may not be completely filled with weld metal. These types of welds are often used to join face-hardened plates from the backer soft side, to install liner metals inside tanks, or to fill up holes in a plate. Resistance welding is a metal fabricating process in which the fusing temperature is generated at the joint by the resistance to the flow of an electrical current. This is accomplished by clamping two or more sheets of metal between copper electrodes and then passing an electrical current through them. When the metals are heated to a melting temperature, forging pressure is applied through either a manual or automatic means to weld the pieces together. Spot and seam welding are two common types of resistance welding processes. Spot welding is probably the most commonly used type of resistance welding. The material to be joined is placed between two electrodes and pressure is applied. Next, a charge of electricity is sent from one electrode through the material to the other electrode. Spot welding is especially useful in fabricating sheet metal parts. Seam welding is like spot welding except that the spots overlap each other, making a continuous weld seam. From (http://en.wikipedia.org/wiki/Welding#_note-27#_note-27)

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