II. Famous people of science and technology: George Stephenson, Robert Slephenson

Text A: «MACHINE-TOOIS»

Machine-tools are used toshape metals and other ma­terials. The material to be shaped is called theworkpiece.Most machine-tools are nowelectrically driven. Ma­chine-tools with electrical drive are faster and moreac­curate than hand tools: they were an important element in thedevelopment of mass-production processes, as they allowed individual parts to be made in large numbers so as to beinterchangeable.

All machine-tools havefacilities for holding both the workpiece and the tool, and for accurately controlling the movement of the cutting toolrelative to the workpiece. Most machining operations generate largeamounts of heat, and use coolingfluids (usually a mixture of water and oils) for cooling andlubrication.

Machine-tools usually work materials mechanically but other machining methods have been developed lately. They include chemical machining,spark erosionto machine very hard materials to any shape by means of a continuous high-voltagespark (discharge) between an electrode and a workpiece. Other machining meth­ods includedrilling using ultrasound, and cuttingby means of a laserbeam. Numerical control of machine-tools andflexible manufacturing systems have made it possible for complete systems of machine-tools to be used flexibly for the manufacture of arange of pro­ducts.

Vocabulary:

machine-tools — станки

electrically driven — с электроприводом

shape — форма

workpiece — деталь

accurate — точный

development — развитие

to allow — позволять, разрешать

interchangeable — взаимозаменяе­мый

facility — приспособление

relative —относительный

amount — количество

fluid — жидкость

to lubricate — смазывать

spark erosion — электроискровая об­работка

discharge — разряд

by means of — посредством

beam — луч

drilling — сверление

flexible — гибкий

range — ассортимент, диапазон

Text B: «LATHE»

Lathe is still the most important machine-tool. It pro­duces parts ofcircular cross-section by turning the workpiece on its axis and cutting itssurface with a sharp stationary tool. The tool may be movedsideways to pro­duce a cylindrical part and moved towards the workpiece to control thedepth of cut. Nowadays all lathes are power-driven by electric motors. That allows continuous rotation of the workpiece at a variety of speeds. The mod­ern lathe is driven by means ofa headstock supporting a hollowspindle on accurate bearings and carrying either achuck or a faceplate, to which the workpiece is clamped. The movement of the tool, both along thelathe bed and at right angle to it, can be accurately controlled, soena­bling a part to be machined to closetolerances. Modern lathes are often under numerical control.

Vocabulary:

lathe — токарный станок

circular cross-section — круглое попереч­ное сечение

surface — поверхность

stationary — неподвижный, стационар­ный

sideways — в сторону

variety — разнообразие, разновидность

depth — глубина

headstock — передняя бабка

spindle — шпиндель

chuck — зажим, патрон

faceplate — планшайба

lathe bed — станина станка

to enable — давать возможность

tolerance — допуск

General understanding:

1. What are machine-tools used for?

2. How are most machine-tools driven nowadays?

3. What facilities have all machine-tools?

4. How are the cutting tool and the workpiece cooled during machining?

5. What other machining methods have been devel­oped lately?

6. What systems are used now for the manufacture of a range of products without the use of manual labor?

7. What parts can be made with lathes?

8. How can the cutting tool be moved on a lathe?

9. How is the workpiece clamped in a lathe?

10. Can we change the speeds of workpiece rotation in a lathe?

11. What is numerical control of machine tools used for?

Exercise 4.1. Find English equivalents in the text:

1. обрабатываемый материал

2. электропривод

3. более точный

4. отдельные детали

5. процесс массового производства

6. приспособления для держания резца и детали

7. операции по механической обработке детали

8. высоковольтный разряд

9. сверление ультразвуком

10. резание с помощью лазерного луча

11. гибкие производственные системы

12. детали круглого сечения

13. поворачивать деталь вокруг ее оси

14. двигать в сторону, двигать по направлению к детали

15. глубина резания

16. непрерывное вращение детали

17. движение резца вдоль станины

Exercise 4.2. Translate into English:

1. Токарный станок позволяет производить детали круглого сечения.

2. Деталь зажимается в патроне или на планшайбе токарного станка.

3. Резец может двигаться как вдоль станины, так и под прямым углом к ней.

4. Современные токарные станки часто имеют циф­ровое управление.

Text С: «MILLING MACHINE»

In a milling machine thecutter (фреза) is a circular device witha series of cuttingedges on itscircumfer­ence. The workpiece is held on a table that controls the feed against the cutter. The table has three possible movements:longitudinal, horizontal, andvertical; in some cases it can also rotate. Milling machines are the mostversatile of all machine tools.Flat or contouredsurfaces may be machined with excellent finish and ac­curacy.Angles, slots, gear teeth and cuts can be made by using various shapes of cutters.