Урок 10

Завдання 1. Уважно прочитайте подані нижче слова та їх переклад, запам'ятайте їх значення:

fluid - рідина .

to cause - причиняти, завдавати, викликати

tо rub - тертися

to damage пошкоджувати

to tend (to) - мати тенденцію (до чогось)

to expand - поширювати(ся)

to cool - охолоджувати(ся)

to serve - служити, годитися

instance - окремий випадок, приклад

slide - ковзна частина

to lubricate - мастити, змазувати

to clog – заcмічувати (ся), заважати

particle - частка, крихта

to interfere (with) - перешкоджати

alkali - луг

soluble - розчинний

oil - мастило

fat - жир

viscosity - в'язкicть, тягучість

to aggravate - обтяжувати

hazard -ризик, небезпека

gear - шестерня, зубчаста передача

reaming - розсвердлювання

cautiously - обережно

compound - сполука

to employ - вживати, застосовувати, використовувати

Завдання 2. Прочитайте та перекладіть такі слова, ґрунтуючись на їх подібності до слів рідної мови.

to assist, emulsion, mixture, to mix, to sulphurize, to chlorinate, test, mineral, deformation.

Завдання 3.Прочитайте та перекладіть подані нижче групи слів. Визначте, до яких частин мови вони належать та назвіть їх словотворчі особливості. Доповніть таблицю словотворчих елементів.

to rub - rubbing;

accuracy - inaccuracy;

to cool - cooling- precooling - coolant;

to lubricate - lubricant – lubrication;

to assist - assistant - assistance;

fat - fatty;

thread - to thread - threading;

to tend - tendency;

to damage – damage;

viscosity - viscous;

oil - oiliness.

Завдання 4. Дайте українські еквіваленти таких словосполучень:

cutting fluid; resulting temperature rise; to serve other purposes; in certain instances; mineral oils; anticorrosive properties; to increase cult me speeds by 10-33%; low-viscosity oils; complicated machines; gear cutting; in addition to cooling; fire hazard; hard and fast rules; straight (plain) oils.

Завдання 5. Уважно прочитай текст 10А. Постарайтеся якомога точніше зрозуміти та запам'ятати його зміст:

TEXT 10A

Most metal machining operations require the use of some type of cutting fluid. Machining of metals causes deformation, rubbing and friction. The resulting temperature rise can warp the work and damage or excessively wear the tool. Also, the me­tal win tend to expand, causing inaccuracies in the work. Cutt­ing fluids are used mainly for cooling, but they may serve other purposes. In certain instances the surface finish is improved by the use of a cutting fluid. Often the fluid also serves so lubricate the slides of the machine or to protect the machine from corrosion. In many operations the fluid washes away metal chips and particles that could clog or interfere with «ho tool and the machine.

Lubricants or coolants are applied to the work and tool to assist in cutting operations. They include air; water containing an alkali; an emulsion of soluble oil; and water; straight mineral oils or mixtures of mineral oils with fatty oils; and straight oils or mixed oils that have been sulphurized chlori­nated or both.

Water is he best coolant, but emulsions that provide some lubrication and anticorrosive properties are generally used for all high-speed machining. They increase cutting speeds by 10-З5%. Low-viscosity oils are used in complicated machines to lubricate the machine and cool the tool, particularly in machining brass, aluminium and magnesium. Water aggravates the fire hazard of mag­nesium. The sulphurized oils are used for low cutting speeds on operations such as thread me gear cutting reaming, and broaching primarily to provide good surface finish and high dimensio­nal accuracy, oils increase cutting speeds by 8-15%.

All fluids must be applied cautiously to the tool. The precooling of the fluids, particularly the emulsions, increases tool life. In general, if cooling is the primary requirement, an oil-and-water emulsion is used. if lubrication of slides or other parts is required in addition to cooling, a mineral oil compound is usually employed. There are, however, no bard and fast rules, and in man cases only experience or actual test will tell the type of cutting oil to use.

Завдання 6. Знайдіть в тексті таку інформацію:

1. З якою метою застосовуються змащувально-охолоджуючі рідини (емульсії)?

2. Які мастила та охолоджувачі застосовуються при обробці металів?

3. З якими параметрами процесу обробки пов’язане застосування тієї чи іншої змащувально-охолоджуючої рідини?

Завдання 7. Випишіть з тексту назви всіх змащувально-охолоджуючих речовин.

Завдання 8. Які з поданих нижче речень містять інформацію, відповідну до змісту тексту І0А:

1. In the selection of the satisfactory cutting lubricant.

It is necessary to take into account the cutting speed and depth of cut as well as the nature of materials-being machined.

2. Low speed and heavy cuts require little cooling or lubrication.

3. Brittle materials such as cast iron are often cut without the use of lubricant, although emulsions of soluble oil in water are sometimes employed.

4. Cutting oils serve a three-fold purpose in metal cutting processes: they act as a lubricant, a coolant and wash away the chips as fast as they are formed.

5. Satisfactory cut tine lubricants should possess the property known as oiliness.

6. The term viscosity indicates the relative non-fluidity of an oil, and is usually determined with a viscosimeter.

7. Shallow cuts at high speeds require good coolants, therefore emulsions of soluble and sulphur-base cutting oils are frequently employed.

Завдання 9. прочитайте поданий нижче текст, яку додаткову до текстe 10А інформацію він містить?

Lubricants are employed in engineering practice for two reasons; to diminish (to reduce) friction between, the surfaces of machine parts; and to diminish friction between a cutting tool and the material being cut, and at the same time serve to dissipate the heat developed in the operation.

Liquid hydrocarbons are the most commonly used lubricants because they are inexpensive, easily applied, and good coolants. In most cases, petroleum fractions are applicable, but for special conditions such as extremes of temperature, select synthetic liquids may be used. At very high temperatures, or in places where renewal of lubricants is impossible, solid lubricants may be used. It is often desirable to add various chemicals to lubricating oils to improve their physical pro­perties or to obtain some needed improvement in performance (antiwear and friction-reducing additives, for example).

Boundary conditions are encountered in many metal-forming processes in which the pressures required to deform the metal are too high to allow an oil film to form. In such applications fatty oils or lubricants containing fatty materials are employed to reduce the friction and wear.

During World War II, synthetic lubricants were extensively employed by Germany as substitutes for mineral lubricants, which were in short supply. Some of these were in fact superior to mineral lubricants in some applications. Since the war, the use of synthetics for special applications, where their, perfor­mance Justifies the higher costs, has steadily increased. Their main advantage is that they have a greater operating range than a mineral oil.

Завдання І0. перекладіть подані нижче речення:

1. Lubricant is a gas, liquid, or solid used to prevent contact of parts in relative motion, and thereby (by this) reduce, friction and wear.

2. In many machines, cooling by the lubricant is equally important.

3. The lubricant may also be used to prevent rusting and the deposition of solids on close-fitting parts.

4. The most useful solid lubricants are those with a layer structure, graphite being among them.

5. a unique type of solid lubricant is provided by the plastic polytetrafluoroethyiene (PTFE).

6. A lubricating grease (мастило) is a solid or semi fluid lubricant comprising a thickening agent in a liquid lubricant.

7. Other ingredients imparting special properties may be included.

Завдання 11. Прочитайте текст І0Б, запропонуйте один або кілька варіантів заголовка до тексту.

TEXT 10Б

Tool life is controlled by many factors and the more impor­tant ones are listed below.

1. The rigidity of the work., tool and machine.

2. The cutting fluid used and its application.

3. The angles to which the tool has been ground.

4. The rate of feed and depth of cut.

5. The properties of the material being cut.

6. The cutting speed.

7. The properties of the cutting tool material.

Cutting speed is one of the most important, factors in determining tool life. a small increase in cutting speed rapidly reduces the tool life, while a small decrease in cutting speed greatly increases tool life.

The reason for this is that the cutting speed is closely tied up with the heat generated at the cutting edge of the tool. if this heat cannot, be dissipated (got rid of) quickly enough, then the temperature of the tool increases and it starts to soften and becomes blunt quicker. Heat is generated during cutting due to:

1. The internal breakdown of the metal structure of the work-piece during cutting;

2. The friction between the chip and the tool.

Any increase in cutting speed results in an increase in the heat energy generated at the cutting edge.

A cutting tool must have the following properties:

1. Sufficient strength to resist the cutting forces;

2. it must be hard enough to resist wear and give an adequate life between regrinds; 3. it must be able to retain its hardness at high temperatures.

Завдання 12. Перекладіть такі слова та словосполучення з тексту;

rate of feed; depth of cut; tool life; to dissipate heat; to get rid of; to regrind; to retain, hardness

Завдання І3. Передайте зміст тексту рідною мовою.

Завдання 14. На основі текстів уроку та завдань до них складіть письмове повідомлення на тему "Змащувально-охолоджуючі речовини та їх використання при механічній обробці металів" (І0 тис. знаків).

"NС units, their advantages and peculiarities, their application.”