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контрольная работа: Text 1 1. A. Read the text about lathe. It is divided into three parts. Match these parts with the following headings: A) Main Parts of Turning Machine B) Purpose of Lathe C) Principle of Operation of Lathe LATHE 1. The most useful and versatile machine in the workshop is turning machine – lathe. As name shows, it is used for turning different objects and parts. However, besides turning many other operations can be performed on a lathe, such as drilling, reaming, tapping and by employing suitable adapters operations of milling and grinding may be carried out wi
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Содержание
ИДЗ № 2
Вариант 1
READING
Text 1
1. A. Read the text about lathe. It is divided into three parts. Match these
parts with the following headings:
A) Main Parts of Turning Machine
B) Purpose of Lathe
C) Principle of Operation of Lathe
LATHE
1. The most useful and versatile machine in the workshop is turning machine – lathe. As name shows, it is used for turning different objects and parts. However, besides turning many other operations can be performed on a lathe, such as drilling, reaming, tapping and by employing suitable adapters operations of milling and grinding may be carried out without difficulty.
2. The lathe consists of the following basic parts: the bed, the headstock, the tailstock, the saddle (carriage) with the tool post and the driving and gear mechanism.
The bed is a base for supporting and aligning the components of the machine. At the opposite ends of the bed there is a headstock and a tailstock.
3. The headstock carries a pair of bearings in which the spindle rotates. The spindle holds the workpiece and rotates with it. The headstock also incorporates the driving and gear mechanism. The parts of this mechanism are the feed shaft and change gear box. The feed shaft is designed for driving the tool post, and the change gear box drives the spindle of the lathe at various speeds. Tapered centers in the nose of the spindle and of the tailstock hold the work firmly between them. The tool post is driven along the saddle either forwards or backwards at a uniform speed. That is why the operator is capable of making accurate cuts and giving the work a good finish.
There are many types of lathes but all of them operate on the same principle: the workpiece is revolved by power and a cutting tool is brought against it, removing metal in the form of chips.
The other principle of operation is that used in milling, grinding and drilling machines. In these machines the tool is fixed and the work is moved to and fro against it in a horizontal plane.
B. Fill in the scheme about construction of the lathe, its purpose and
principle of work.
Text 2
A. Read the text about the law of conservation of mass and energy.
Agree or disagree to the statements on the text.
1) The mass of a lump of coal is much greater than the ashes that result from its burning.
2) Every change in the matter does not involve a change in energy.
3) Energy can't be freely transformed from one variety to another.
4) The kinetic energy possesses by falling water can be transformed into electricity.
5) We should find that a definite quantity of energy of kind gives no definite equivalent quantity of another.
THE LAW OF CONSERVATION OF MASS AND ENERGY
All bodies possess mass which is an inherent property of all matter. In our experiences we have observed that the outward appearance of matter is constantly changing, so that it would be reasonable to assume that it’s mass also undergoing some sort of change. To test this assumption, let us take a lump of coal and burn it. The mass of this lump is certainly much greater than the ashes that result from its burning, but should we collect the gas formed and account for all the other materials concerned in the burning and weight them, we should find that the total mass has remained unchanged. All the experience accumulated in the study of every change in matter shows that in all the changes the total mass is neither increased nor diminished.
But every change in the matter involves a change in energy. This energy makes its appearance in a number of forms such as heat, electrical energy, chemical energy, radiant energy, kinetic energy (energy possessed by moving bodies), or potential energy.
Experiments carried out over a long period of time have shown that energy is like mass in that energy in all transformations is neither created nor destroyed. This generalization is known as the law of conservation of energy. For example, if a piece of hot metal is placed into cold water, the metal is cooled and water is heated so that the metal low energy and the water gain it. We also find that energy can be freely transformed from one variety to another. Thus the heat energy derived from the burning of coal may be changed into the kinetic energy of locomotive. Similarly, the kinetic energy possessed by falling water can be transformed into electricity. If we were to take a close study of such transformation, we should find that definite quantity of energy of kind always gives a definite equivalent quantity of another.
In any action involving the change of one form of energy into another no gain or loss in total energy takes place. In other words: whenever a quantity of one kind of energy is produced, on exactly equivalent amount of another kind must be used up.
B. Complete the following sentences using the information from the text.
VOCABULARY AND GRAMMAR
3. Match the words with their definitions.
TRANSLATION
4. Translate the sentences from Russian into English.
1. Все резцы и фрезы должны иметь острую режущую кромку.
2. Полагают, что это изобретение сэкономит большое количество металла.
3. Мы заставили его прекратить этот глупый спор.
4. Все современные токарные станки оборудованы электроприводом.
5. Движение инструмента контролируется с высокой точностью.
6. Электропривод позволяет обрабатывать заготовку на различных скоростях.
7. Шлифовальные станки (grinders) удаляют металл с помощью абразивного колеса.
8. Токарный станок позволяет производить детали круглого сечения.
9. Резец может двигаться как вдоль станины, так и под прямым углом к ней.
10. Металическая заготовка протягивается через самый большой станок для заготовки проводов крупного сечения.
WRITING
5. Write an abstract of the text below.
SAFETY DEVICES IN SHAPERS
The shaper is considered by many to be the most dangerous machine in the shop; however, several devices are used to mitigate the risk. The first is a plastic guard supplied with the shaper that sits above the cutter. It has a bearing in the center of it which allows it to spin freely and serves to limit inadvertent contact by human hands with the cutter.
Jigs and fixtures are also a big help in reducing injury, and generally result in better cuts. A very small device, but important one is the starter pin, or fulcrum pin supplied with the machines. This is simply a metal rod, threaded on one end which screws into a hole located a few inches away from the cutter. Holding the work piece against the starter pin, and then feeding it into the cutter is the proper way to start a freehand cut.
Probably the best and also most expensive safety device would be a power feeder. While these were probably not designed as a safety feature they keep hands far from the cutters, and will hold both down the work piece and press it against the fence with a great deal of force. The feeder will also control the speed at which the board is fed past the cutter. Both of these details are critical to nice smooth, burn-free shaping. These power feeders are generally three or four-wheeled, and are capable of at least two speeds. The speed change is made by changing metal drive gears within the power head. The wheels themselves are usually a semi-soft rubber or similar material which prevents them from slip
