Exercises. I. Use the following words and phrases in sentences of your own:

I. Use the following words and phrases in sentences of your own:

to tap, drilling machine, to ream, vertical spindle drilling machine, quill, to swing, crank, ratchet lever, radial arm, to accomplish, multiple-spindle drilling machine, sensitive drilling machine

II. Retell the text giving answers to the following questions:

1. What operations may be performed on drilling machines? 2. How are drilling machines classified? 3. Where does the drilling machine spindle rotate? 4. How is the spindle sleeve moved? 5. What is provided by such a movement? 6. What are vertical spindle drilling machines? 7. What structural feature gives the upright drilling machine its name? 8. How is a v/ide range of speeds obtained on this machine? 9. What does the feed mechanism of the drilling machine consist of? 10. What is the function of the feed shaft? 11. How can the table be moved? 12. What does the ratchet lever serve for? 13. How are speed changes effected in the upright drilling machines? 14. When are the heavy duty drilling machines used? 15. What is the plain vertical spindle machine employed for? 16. For what type of work is the sensitive drilling machine designed? 17. What are multiple-spindle drilling machines and what are they used for? 18. How many spindles may be used in a fully-automatic multiple-spindle drill head machine? 19. For what kind of work is the radial drilling machine intended? 20. What main parts does the radial drilling machine consist of? 21. What range of spindle speeds and feeds may the radial drilling machine have?

III. Give derivatives from the following words and translate them into Russian:

to bore, light, sensitive, high, to construct, to employ, to vary, to provide, to move, to adjust, to drill, to revolve

IV. Give different meanings of the following words:

arm, head, work, way

V. Translate the following sentences observing different meanings of the italicized words and word combinations:

1. Drilling means removing some metal from the work. 2. A drilling machine is by all means the most important machine for drilling holes of different size in metal. 3. By no means can a boring machine be used at speeds exceeding permissible

ones, as it may result in breakage. 4. Boring may be performed on drilling machines. 5. The main driving motor drives the shaft by means of Vee-belts. 6. When we speak of the operations performed on the drilling machine, we mean such operations as tapping, reaming, lapping, etc.

VI. Find the predicates in the following sentences. Translate the sentences into Russian:

1. The hydraulic sliding head is said to be actuated by a large diameter cylinder. 2. We know the hydraulic sliding head to contain the feed and rapid traverse hydraulic pumps. 3. The two work spindles are driven by heavy helical gears through pick-off gears for controlling the spindle speeds. 4. The main drive motor, mounted on top of the head, drives the main shaft by means of Vee-belts. 5. On the outside of the plate there is a table showing spindle speeds and the proper pick-off gears to be used for the required speed. 6. This machine may be used for boring operations in shorter cylinders.

VII. (a) Read and translate the text without using a dictionary:

A semi-automatic, vertical boring machine is designed to facilitate the machining of heavy components such as railway wagon wheels, with weights up to 700 lb. The machine has two hydraulically-operated 5-jaw chucks mounted on a table which can be traversed to bring either beneath the spindle¹. Power for operation of the chucks, the movement of the table, and the feed of the spindle, is supplied by a separate unit. The spindle is 7 ft long, and is supported on two taper roller bearings at the top and one at the lower end. It is driven by a 75-h.p. variable motor, and speeds suitable for a variety of bore sizes can be obtained. The boring bars are fitted with throw-away carbide inserts², which are clamped in position, two square roughing and two cylindrical semi-finishing tools being arranged alternately, 90 deg. apart. A surface speed³ of 225 ft per min is normally employed, and the spindle is fed at the rate of ¹/₁₆ in. per rev. No coolant is employed.

1. to bring either beneath the spindle - для того, чтобы подвести каждый из этих патронов под шпиндель

2. throw-away carbide inserts - сменные карбидные вставки

3. surface speed - скорость резания

(b) Retell the text.

VIII. Using the following words and word combinations describe all drilling machines that you know:

drilling machines, to be old machine tools, to employ, drilling holes, operations, tapping, reaming, and lapping, to be performed, to fall, various classes, upright spindle drilling machines, to have the spindle, to be placed, a vertical position, to be classified, heavy duty, plain and sensitive machines, multiple-spindle drilling machines, to be provided, a large number of spindles, to be used, simultaneous

drilling, many holes, the radial drilling machine, to have a vertical column, to carry a radial arm, to move in a horizontal and vertical planes, the drill, to be moved over the stationary work, any position, to be adapted, heavy work

IX. Describe the principle of operation and construction of the radial drilling machine shown in Fig. 51.

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