II. Дайте русские эквиваленты следующих словосочетаний: 4

pre-fabricated 2 х 2 x ¼ in T-section track; sprocket teeth; trolley wheels; wear and noise factor considerations; design approach; 42 volt supply; three-phase motor; vehicle manufacture; wheeled trolley arrangement; square section track.

III. Прочтите текст IIА и постарайтесь озаглавить его. Время на чтение - 3 минуты.

Text IIА

There are various patented overhead conveying systems now available, and it would be impossible to review every one in de­tail covering their various design and operational characteris­tics. One of them, for example, uses pre fabricated 2 x 2 x ¼ in T-section track formed of standard lengths bolted together. The trolley and the drive cable are propelled round the track by sprocket teeth engaging with lugs on the cable. The trolley wheels are cadmium plated for wear and noise factor considera­tions. Other systems, using identical principle, employ speci­al rubber, polyprene, or coated trolley wheels in similar kind of configurations.

Another interesting installation shows entirely different design approach to overhead conveying. The carrier rail is a double-T with a live electric rail, using 42 volt supply. The trolley is individually driven by a three-phase motor. The speed of travel is variable and a brake can be included in the drive assembly to provide minimal stopping distance. The whole system is therefore suited to individual remote automatic control of all the carriers.

This type of overhead conveying systems offers an economic solution to many handling problems, and can be adapted to suit most layouts, or for movement between floors, if required. Sche­mes of this kind have been very successfully applied in various kinds of warehouses, in different sectors of textile industry, in foundries and in vehicle manufacture.

The two above examples illustrate two distinctly different approaches to overhead systems; namely in one case a simple wheeled trolley arrangement towed by a driven cable, and in the other individually power-driven carriers. Between the two de­signs there are numerous patented designs to be found. One of them, for instance, consists, of a chain running in a square section track. Steel pendants carry loads up to 56 lb. To carry loads above this two or more pendants are linked together. The chain itself is assembled from pairs of riveted links in both the vertical and horizontal planes. Ball bearing wheels are arranged in each link to carry the load on to the track. It is claimed that this arrangement is particularly suited to the avoidance of problems at bends or changes of direction. The drive is by motor and reduction gears through a V-belt.

IV. Расскажите подробно об общих чертах и различиях в конструкции подвесных конвейеров, описанных в тексте IIА

§ 3. Винтовые конвейеры

Текст III

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

1. screw conveyor винтовой конвейер, шнек

2. pitch шаг

3. plate листовая сталь, пластина

4. helix винтовая поверхность, геликоид 5. trough желоб, лоток

6. thrust давление, толчок

7. bearing подшипник

8. discharge разгружать

9. bottom днище

10. incline наклон, наклонность

11. dust tight пыленепроницаемый

II. Дайте русский эквивалент словосочетания a U-shaped trough.

Назовите другие словосочетания, построенные по этому же принципу, которые встречались а текстах §1 и §2

III. Прочтите текст III и выясните, где в тексте содержатся отве­ты на следующие вопросы: 5

1) What is the construction of a screw conveyor?

2) What are the capacity changes with the change of the inclination of the screw conveyor?

3) What are the advantages of the screw conveyor?

Text III. SCREW CONVEYORS

The screw conveyor usually consists of a long-pitch plate-steel helix mounted on a shaft carried in bearings within a U-shaped trough. As the element rotates, the material fed to it is moved forward by the thrust of the lower part of the helix and is discharged through openings in the trough bottom or at the end.

Screw conveyors can be operated with the path inclined forward, but the capacity decreases rapidly as the inclination increases. A standard pitch screw inclined at 15° with the hori­zontal has 70 per cent of its horizontal capacity; if it is in­clined 25° the capacity is reduced to 40 per cent; if it is in­clined 45° the material will more along the floor of the through but at a greatly reduced rate. For steep inclines the helix may have a short pitch, and the trough may be made tabular; then the capacity loss is less. Thus with a 45° incline such a conveyor has a capacity about 50 per cent of its capacity when horizontal.

The screw conveyor does always find favour with engineers, but properly applied it does a good job and often its cost will be about one-half that for any other type of conveyor. It is a simple machine to maintain, and it is readily made dust tight. For many functions it is the best type of a conveyor.

Fig. 3. Screw conveyor

IV. Переведите на русский язык части текста, в которых содержатся ответы на вопросы упр. III.

Текст III А

I. Выясните значения следующих слов и словосочетаний из текста IIIА и постарайтесь запомнить их:

1. cold rolled, cold rolling 7. paddle mixer

2. strip 8. storage bin

3. to attain 9. duet nuisance

4. outer edge 10. hardened-face concrete

5. succession 11. tar

6. marine screw propeller 12. ribbon helix

II. Прочтите текст IIIA к и выясните, что говорится в нем о винто­вых конвейерах. Время на чтение - 2 минуты

Text III A. SCREW CONVEYORS FOR DIFFERENT TYPES OF LOADS

A well-designed screw conveyor for non-abrasive non corrosi­ve materials has a steel helix cold rolled in one continuous strip between bearings, rather than in short sections. By cold rolling the helix attains a tapered section with greatest thickness at the shaft and with the thin outer edge.

6

If the conveyor is to handle food products or other materials which may be discolored through contact with steel plate, the rotating parts or the entire conveyor may be of stainless steel, bronze, aluminium, normal metal, etc, though at considerable increase in first cost.

If it is desired to mix materials the helix is made segmental or bladed, like a succession of marine screw propellers, and is then referred to as a paddle mixer. One each application is mixing water with ashes when discharging from a storage bin to reduce the dust nuisance.

For ashes, ores, etc., the helix may be of cast-iron sections bolted to the shafts and the trough may be made of cast-iron of hardened-face concrete.

For sticky materials, like hot tar or asphalt, a ribbon he­lix is preferable. This construction prevents buildup along the line between helix and shaft where it would cause loss of handling capacity.

III. Составьте план текста IIIA и перескажите его по Вашему плану

§ 4

I. Прочтите текста IV, V, VI и постарайтесь понять их содержание

Text IV. CHAIN AND FLIGHT CONVEYOR

An unusual feature of the 200 mm chain and flight conveyor is the employment of a single strand calibrated link chain tested to 29 000 lb and weighing only 2 lb per foot.

The 1200 mm long drive end incorporates a mounting for the drive motor, a shaft-mounted speed-reduction gearbox and a flanged outlet. The 1200 mm tail end incorporate a flanged tut inlet, clean-out slide and self aligning, single screw chain adjustment.

(Materials Handling News, October 1980)

Text V. LOW POWER CABLE CONVEYOR

Now marketed in Britain is a cable conveyor which is claimed to use less than half the power of a conventional chain, and flight conveyor and one-third that of a screw conveyor. An interesting feature is the principle of mounting either two or four drive cables. This allows greater flexibility of movement, lower wear on the slats, and free movement of cables over the drive.

Up to 10 000 maintenance free hours are claimed for any unit in the range. The five models offer capacities from 30 to 300 tonnes/hr in completely enclosed steel box sections, and are suitable for handling all types of grain, granulated and ground, materials.

(Materials Handling Hews, September 1980)

Text VI. TELESCOPIC BELT CONVEYORS

Designed for both loading and unloading operations is a range of telescopic belt conveyors for permanent floor mounting or mobile applications. The range includes unite of up to 12 m overhang, with 1200 mm belt width. Standard speed of operation is 15 m/minute but alternative belt speeds are available.

Built to operate with loads of 50 kg/m over their entire length, the conveyors will also support loads of up to 800 kg/m plus a further 100 kg/m point loading at the extremity of the boom.

Other features include electrical controls at the far and of the boom and emergency stop lever.

(Materials Handling News, October 1980)

II. Дайте техническую характеристику каждого из конвейеров, описанных в текстах: IV, V, VI

III. Ответьте на следующие вопросы:

1. Что нового Вы узнали из прочитанных выше текстов?

2. Что заинтересовало Вас как будущих специалистов в конструкции описанных конвейеров?

3. Какие из описанных конвейеров находят в настоящее время наиболее широкое применение в производстве?

4. Какие, по Вашему мнению, проблемы предстоит решить в области конструирования конвейеров?