§ I. Ленточные конвейеры 1

Текст I

I. Запишите в тетрадь следующие слова и словосочетания и поста­райтесь запомнить их значения:

1. belt конвейерная лента

belt conveyor ленточный конвейер

2. conventional обычного типа, традиционный

3. terminal drum концевой барабан

4. driving drum приводной барабан

5. idler поддерживающий ролик

6. accessories вспомогательные устройства

7. impregnation пропитка, импрегнирование

8. wear-resistant износоустойчивый

9. impact-resistant противоударный

10. fire-resistance огнеупорность, жаропрочность

11. horsepower мощность

I I. Дайте русские эквиваленты следующих словосочетаний:

1. belt tension 4. conveyor system

2. protection and control devices 5. high-capacity conveying

3. belt cleaning facilities 6. mining applications

I I I. Проанализируйте первое предложение из текста I, выделив в нем субъектный инфинитивный оборот, и переведите его на русский язык

I У. Прочтите текст I и постарайтесь выяснить следующее:

1) What main parts does the conventional belt conveyor comprise?

2) What is the most important part of a conveyor system? Why?

3) What qualities must the belt possess?

Отметьте для себя, какие части текста I содержат ответы на эти вопросы

Text I. ВELТ CONVEYOR COMPONENTS

The conventional belt conveyor can be said to comprise: (1) a belt to carry the material and transmit the tension; (2) a driving unit to transfer power from the motor to the belt; (3) terminal drums with intervening idlers and supporting structure; and (4) accessories which include devices for maintaining belt tension, arrangements for loading and unloading the belt, protection and control devices, belt cleaning facilities, etc. Of all these features it is the carrying belt which is the most important, for not only is the belt by far the most ex­pensive part of a conveyor system, it also governs the horse­power that can be transmitted, and hence the ultimate capacity and length of the conveyor.

Normally the belt used for high-capacity conveying has two main components: the carcase which transmits the tension and the protective cover and impregnation. In order to fulfil its function the belt must possess the following qualities. It must have sufficient strength to transmit the necessary ten­sion and yet be sufficiently flexible to bend around the ter­minal and driving drums safely and conform to the angle of the troughing idlers under its own weight. The belt must also be wear-resistant and have good impact-resistant properties. For certain mining applications additional qualities are required of the belt such as low electrical resistivity and high fire resistance.

Fig.1. Belt conveyor

У. Назовите элементы ленточного конвейера, изображенного на схеме I 2

УI. Переведите на русский язык части текста I, в которых содер­жатся ответы на вопросы упр. IУ.

Текст IА

I. Определите значения следующих слов и словосочетаний из текста IA, и постарайтесь запомнить их

1. oil (grease, food) stains 6. excess heat

2. woven cotton belting 7. to contaminate

3. wax 8. option

4. stain resistant belt 9. fragile (products) 5. easy-to-clean belt 10. cushion

6. protective coating 11. incline

II. Прочтите текст IА и постарайтесь выяснить, какие требова­ния предъявляются к конвейерным лентам. Время на чтение -4 минуты

Text IA. SELECTING CONVEYOR BELTING

Many types and configurations of conveyor belting are avail­able to handle specialized production problems.

Both natural fiber and synthetic material can be combined to provide belting that is easy to clean, resistant to oil, grease, food stains, hot and cold temperatures, abrasion, and cuts and meet government standards for cleanliness where necessary.

Prior to World War II woven cotton belting impregnated with wax or covered with natural rubber was the standard conveyor material for industries requiring stain resistant and easy-to-clean belts. Nowadays companies are constantly adding new mate­rials to the family of protective coatings for conveyor belting.

A selection of conveyor belting must satisfy three major requirements. First the belting must contain a structural mate­rial that will keep the belt from stretching under tension. This tension is caused by the weight of the load, the friction in the pulley system supporting the belt and the pull necessary to lift and lower the belt between elevations.

The second major requirement for conveyor belting is the abi­lity to be continually flexed around pulleys without breaking down or generating excess heat. Each time as belt section is moved over or around a pulley it is subjected to compression on the pulley side and tension on the side away from the pulley.

Therefore, natural or synthetic materials must be combined in the belt in such a manner as to withstand the continual flexing over a normal life-time.

The third major requirement for conveyor belting is the most important to the user. Each section of belting must be protect­ed by a suitable covering or coating that protects the inner parts of the belting from adverse effects of the user's products being conveyed or protects the products from being contamina­ted by the belting. Since users' requirements differ, many types of covering materials must be available. Some of the require­ments for a covering material include: easy to clean; resist­ant to product abrasion; resistant to oils and greases; resis­tant to changing color. Since no single covering will be equal­ly effective against all of these requirements, the user makes his selection on the most important criteria for application.

In addition to the three major requirements for a selection of conveyor belting, a user may require other options that can be provided during the fabrication of the belting. For example, if the user is handling fragile products, the cover can incor­porate material to provide a soft cushion for the products. If products are to be conveyed up or down inclines, the belting may be provided with special arrangements to hold the products during all types of movements.

III. Расскажите подробно о каждом из трех основных требований, предъявляемых к конвейерным лентам