II. Reading

Ex.5. Read and translate the text.

Text a. Lathes

A lathe is known to be a machine tool for producing and finishing surfaces of workpieces. The machine is designed to hold and revolve work around an axis of rotation so that it may be subjected to the action of a cutting tool moving in a horizontal plane through the axis of the wok. When the cutting tool moves in a longitudinal direction or parallel to the axes, the operation is known as “turning”, when it moves in a transverse direction it is known as “facing”. In addition to turning and boring which the machine is primarily designed for, many other operations, such as drilling, threading, tapping, and by employing special adapters grinding and milling may be performed on a lathe.

Lathes are known to be of different designs and sizes. Lathes of comparatively small size, which may be mounted on a bench are termed bench lathers, and are intended or small work of considerable accuracy; lathes provided with tools held in a revolvable turret are called “turret lathes”; lathes in which workpieces to be treated are held in a chuck as known as “chucking lathes”; lathes in which most of operations are performed automatically are named “automatic lathes”.

The engine lathes used for metal – turning operations is fitted with a carriage and cross – slide for clamping and holding the cutting tool. In engine lathes the cutting tools are generally operated mechanically, while in some lathes the cutting tools are guided by hand. The engine lathe consists of the following basic parts: the bed, the headstook, the tailstock, the feed mechanism and the carriage.

The bed is a rigid casting with two longitudinal walls firmly connected by cross ribs integral with the casting. The bed serves as a base to support and align the rest of the machine.

The headstock is firmly bolted to the left – hand side of the bed and carries pair of bearings in which the spindle rotates. The spindle being one of the most important parts of a lathe ,is a steel hollow shaft with a taper bore for the insertion of the live running centre on which the piece to be turned is placed.

The tailstock is a casting carrying a non – rotating sleeve, which together with the nut can be advanced or retracted by means of the tailstock revolving screw operated by the handwheel.

The feed mechanism for both longitudinal and cross feeds of the engine lathe is simple and easy to operate. It comprises a cone of gears, an intermediate shaft and a set of sliding gears.

The carriage is a unit intended for mounting the tool, which slide along the two outer V – type ways in a direction parallel to the spindle axis.

III. Language

Ex.6. Match word and word combinations in column A with those in column B:

A B

1.маховик 2.каретка 3.патрон 4.адаптер 5.проект 6.шліфування 7. оброблена деталь 8. свердління 9.нарізка 10.фрезерування 11.розточування 12.станина

1.workpiece 2.adapter 3.design 4.drilling 5.milling 6.threading 7.grinding 8.boring 9.carriage 10.chuck 11.bed 12.handwheel

Ex.7. Fill in the blanks using the following words:

a) Bed, b) finishing, c) handweel, d) headstock, e) grinding and milling, f)engine lathe.

1. A lathe is known to be a machine tool for producing and _______ surfaces of workpieces.

2. In addition to turning and boring by employing special adapter a lathe may perform and ________ .

3. _________ used for metal – turning operations is fitted with a carriage cross – slide.

4. _________ is a rigid casting with two longitudinal walls firmly connected by cross ribs integral with the castings.

5. _________ is located and firmly bolted to the left hand of the bed and carries a pair of bearings in which the spindle rotates.

6. The tailstock is a casting carrying a non – rotating sleeve which can be advanced or retracted by means of __________ .

Ex.8. Find the right ending of the sentences and translate these sentences.

1. Lathes which may be mounted on a bench are termed bench lathes and are intended for: …

a)automatic finishing operations;

b) small work of considerable accuracy;

c)boring and turning workpieces of various diameters.

2. In engine lathes the cutting tools …

a) are generally operated mechanically;

b)are generally operated by hand;

c) are generally operated antomatically.

3. The bed serves …

a)for running the lathe at different speeds ;

b)as a motor shaft;

c) as base to support and align the rest of the machine;

4. The spindle being one of the most important parts of a lathe , is …

a) accurately threaded for chucks to be screwed on it;

b) a steel hollow shaft with a taper bore for insertion of live centre;

c) located and firmly bolted to the left – hand side of the bed.

5. The tailstock located at the right – hand side of the bed is: …

a) a rigid casting with two longitudinal walls;

b) fitted with a carriage ;

c) a casting carring a non – rotating sleeve which can be advanced or retracted.

Ex.9. Translate the following sentences paying attention to the Subjective Infinitive construction.

1. The lathe is known to be regularly furnished with a multiple disc clutch and brake incorporated in a driving pulley.

2. The headstock and the tailstock is known to be fastened at opposite side of the lathe bed.

3. The independent chuck was said to have been suitable for almost any type of work.

4. This new feed mechanism seems to be simple and easy to operate.

5. The functions of the new lathe proved to be fully automatic.

6. The engine lathe was evident to have been widely used for metal – turning operations.

Ex.10. Find sentences with the Subjective Infinitive construction in the text and translate them.

Ex.11. Put questions to get the following answers:

1. The machine is designed to hold and revolve work around on axis of rotation.

2. Lathes of comparatively small size, which may be mounted on a bench are termed bench lathers.

3. Lathes in which most of operations are performed automatically are named automatic lathes.

4. In engine lathes the cutting tools are generally operated mechanically.

5. The bed servers as a base to support and align the rest of the machine.

6. The feed mechanism for both longitudinal and cross feeds of the engine lathe is simple and easy to operate.