Conventional Machine Tools

Among the basic machine tools are lathes, the shaper, the planer, and the milling machine. Auxiliary to these are drilling and boring machines, grinders, saws, and various metal-forming machines.

A (1)_________, the oldest and most common type of turning machine, holds and rotates metal or wood while a cutting tool shapes the material. The tool may be moved parallel to or across the direction of rotation to form parts that have a cylindrical or conical shape or to cut threads.

The (2)________ is used primarily to produce flat surfaces. The tool slides against the stationary workpiece and cuts on one stroke, returns to its starting position, and then cuts on the next stroke after a slight lateral displacement. In general, the shaper can produce almost any surface composed of straight-line elements.

The (3)________ is the largest of the reciprocating machine tools. Unlike the shaper, which moves a tool past a fixed workpiece, the planer moves the workpiece past a fixed tool. After each reciprocating cycle, the workpiece is advanced laterally to expose a new section to the tool. Like the shaper, the planer is intended to produce vertical, horizontal, or diagonal cuts.

In a (4)________, a workpiece is fed against a circular device with a series of cutting edges on its circumference. The workpiece is held on a table that controls the feed against the cutter. The table conventionally has three possible movements: longitudinal, horizontal, and vertical; in some cases it can also rotate. Angles, slots, gear teeth, and recess cuts can be made by using various cutters.

(5 )_________ - Hole-making machine tools are used to drill a hole where none previously existed; to alter a hole in accordance with some specification (by boring or reaming to enlarge it, or by tapping to cut threads for a screw); or to lap or hone to create a hole.

Drilling machines vary in size and function, ranging from portable drills to radial drilling machines, multispindle units, automatic production machines, and deep-hole-drilling machines.

( 6 )_________ - Grinding is the removal of metal by a rotating abrasive wheel; the action is similar to that of a milling cutter.

(7)_________ - Commonly used power-driven saws are classified into three general types, according to the kind of motion used in the cutting action: reciprocating, circular, and band-sawing machines. They generally consist of a bed or frame, a vise for clamping the workpiece, a feed mechanism, and the saw blade.

( 8 )_________- Cutting processes involve high local stresses, frictions, and considerable heat generation that is why cutting-tool material must combine strength, toughness, hardness, and wear resistance at elevated temperatures. These requirements are met in varying degrees by such cutting-tool materials as carbon steels (steel containing 1 to 1.2 percent carbon), high-speed steels (iron alloys containing tungsten, chromium, vanadium, and carbon), tungsten carbide, and diamonds and by such recently developed materials as ceramic, carbide ceramic, and aluminum oxide. In many cutting operations fluids are used to cool and lubricate. Cooling increases tool life and helps to stabilize the size of the finished part. Lubrication reduces friction, thus decreasing the heat generated and the power required for a given cut.

These specialized machine tools made it possible to manufacture standardized products very economically, using relatively unskilled labor. The machines lacked flexibility, however, and they were not adaptable to a variety of products or to variations in manufacturing standards. As a result, in the past three decades engineers have developed highly versatile and accurate machine tools that have been adapted to computer control, making possible the economical manufacture of products of complex design.

 

Exercise 7. Translate the text and find the English equivalents in the text.

Режущий инструмент; шлифовальный станок; полировать; ручная дрель; станок для глубокого сверления; двигать в сторону; многошпиндельный токарный автомат; фреза; невращающийся инструмент; расширение; съем металла; продольное движение; строгальный станок; направление вращения; выколачивание; коническая форма; станок с возвратно-поступательным главным движением; зубья шестерни.

Exercise 8. Match the following words with the Russian equivalents below:

1) lateral displacement a) сверлильный станок

2) gear teeth b) высадочный пресс

3) turning machine с) резец

4) cutter d) боковое смещение

5) drilling machine е) выдвигать

6) metal-forming machine f) зубья шестерни

7) stroke g) шлифовальный круг

8) to expose h) токарный станок

9) vise j) зажимное приспособление

10) abrasive wheel k) такт

Exercise 9. Look through the sentences and say if they are true (T) or false (F).

1) The shaper is the oldest and most common type of turning machines.

2) The shaper can produce almost any surface composed of straight-line elements.

3) Drilling and boring machines are hole-making machine tools.

4) Commonly used power-driven saws are classified into four general types.

5) The planer moves a tool past a fixed workpiece.

6) The planer is intended to produce vertical, horizontal, or diagonal cuts.

7) Cutting-tool material must combine strength, toughness, hardness, and wear resistance at lowered temperatures.

8) In many cutting operations fluids are used to cool and lubricate.

9) Lubrication reduces friction, thus increasing the heat generated and the power required for a given cut.

10) The principle of action of a saw is similar to that of a milling cutter.

 

Exercise 10. In groups of three, write answers to these questions. The winners are the group that answers the most questions correctly in four minutes.

1) What are the basic conventional machine tools?

2) Which is the oldest and most common type of turning machine?

3) What three possible movements does a table of the milling machine have?

4) What hole-making machines do you know? What are they used for?

5) What type of machine tools is used to produce flat surfaces? How does it work?

6) What three general types are power-driven saws classified into?

7) What is grinding?

8) Why are fluids used in cutting operations?

9) What is the largest of the reciprocating machine tools? How does it work?

 

Exercise 11. Which of these sentences are asyndetic? Read and translate them.

1) Grinding is the removal of metal by a rotating abrasive wheel; the action is similar to that of a milling cutter.

2) The essential features of most milling machines are a power-driven table on which the work is done, and a spindle carrying one or more multiple-toothed cutters, slots or grooves.

3) Modern lathes are highly efficient, accurate, complex devices.

4) The workpiece is held on a table that controls the feed against the cutter.

5) Saws consist of a bed or frame, a vise for clamping the workpiece, a feed mechanism, the saw blade.

6) The tool slides against the stationary workpiece, cuts on one stroke, returns to its starting position and cuts on the next stroke after a slight lateral displacement.

7) Lubrication reduces friction and thus decreases the heat generated and the power required for a given cut.

 

Exercise 12. Translate the sentences from Russian into English using infinitive and gerund constructions:

1) Благодаря процессу охлаждения срок эксплуатации инструмента увеличивается.

2) Назначение токарного станка - придание нужной формы металлической или деревянной заготовке.

3) Строгальный станок, так же как и продольно-строгальный станок предназначен для создания вертикальных, горизонтальных или диагональных срезов.

4) В общем, строгальный станок может обрабатывать практически любую поверхность.

5) Смазка уменьшает силу трения, снижая уровень вырабатываемого тепла и силу мощности, необходимую для выполнения среза.

6) Различные режущие станки используются для обработки углов, желобков и зубьев шестерни.

7) Строгальный станок в первую очередь используется для изготовления плоских поверхностей.

 

Exercise 13. Speak on.

What main categories of conventional machine tools do you know? Describe each of them.