2. Choose the most suitable heading for each part of the text:

1. a) different materials; 6) the production of parts; в) various manufacturing processes.

2. a) the importance of forging process; 6) the enormous importance of forging; в) the results of calculation.

3. a) forged products; 6) the railway car building industry; в) the use of forged products.

4. a) the improvement of structure and quality; б) advantages of forging; в) the cost of forged parts.

5. a) hand and machine forging; 6) hand forging tools; в) hammer blows.

6. a) different methods of forging; 6) forging methods; в) the selection of methods for forging.

7. a) separate operations; 6) heating the metal; в) the process of making a forging part.

8. a) the hammer forging operations; 6) different sequence of operations; в) drawing.

9. a) superior or equal forgings; 6) adaptability of forgings; в) other manufacturing processes.

3. Answer the following questions:

1. What parts are all machines built up of?

2. What manufacturing processes are machine parts made by?

3. In what industry is forging an extremely important process?

4. Nearly every machine shop has a forge division, hasn't it?

5. How many per cents of all the parts which go to make up a railway car are forgings?

6. When does any metal become stronger?

7. On what are hand machine forging operations carried out?

8. What are the chief operations in the process of making a part by forging?

9. What operations does the hammer forging method entail?

4. Make up 10 different types of questions to the text and answer them.

5. Retell the text in your own words making use of the key words from ex. 1 (p. 7). Text 2 forging process

1. Cold working. It refers to room temperature. More exactly, metals are subjected to cold-working if they become permanently harder during the working process.

Hot working. During plastic deformation there is a generation, movement and interlocking of dislocations. The greater the degree of deformation, the larger the number of dislocations, the larger stresses are required to enforce their movement and cause further plastic flow.

2. Forging is “the process of flowing metal under impact or pressure to produce economically specific shapes having certain desired properties”.

The process involves plastic deformation of material at various temperatures.

Plastic deformation at room temperature is known as “cold forging”; at higher temperatures but below the lower recrystallization temperature “warm forging”; above the recrystallization point “hot forging”. Most commercial operations involve hot forging.

3. On any forging machine-hammer, press or upsetter – the basic process of deformation is the compression of a workpiece between flat dies. Consider a cylindrical workpiece placed on the end of a lower die, which is reduced in height by the downward movement of the upper die. “Barrelling” occurs because of friction between the die surfaces and the workpiece ends.

4. Deformation is not uniform throughout the work-piece. Material adjoining the dies remains stationary (because of friction and die chilling) and behaves rather like a rigid cone penetrating the workpiece. Most deformation (barrelling) is in the centre of the workpiece. The figure shows progressive inhomogeneous deformation in a cylindrical workpiece with interface friction.

5. To avoid the workpiece buckling during forging, the length: diameter ratio is normally held to 2.5 or 3:1.

If it is required to elongate a workpiece, narrower dies may be used; frictional restriction axially is lower than that transversally and, therefore, most flow of metal is axial. Dies having specially shaped surfaces (shaped dies) may be used to improve the contours and distribution of the material.

6. Material can be made to flow away from the centre, or gather there. Indeed, centre thickness of material can be somewhat increased.

In “drawing down” the end of a bar we may reduce its cross-section and increase its length. Several strokes may be required while the stock is gradually advanced between the dies. It may be a continuous procedure made with the help of rolling.