|The three-roller crusher:|
|1 - the automotive wheels;|
|2 - the loading trough;|
|3- the block of the upper roller with the shock-absorbing springs;|
|4 - the crushing rollers;|
|5 - the axle of the roller.|
ROLLER CRUSHER (EN: roll crusher; DE: Walzenbrecher; FR: concasseur à cilindres, concasseur à rouleaux; ES: trituradora de cilindros, trituradora de rodillos; RU: валковая дробилка) is the installation for the crushing of the materials (ores, building stone, and so on) by the rollers, which are rotating into the opposite directions, or by the rotating rollers with the stationary jaw. For the first time, the roller crusher has been manufactured during the 1806 within the Great Britain, and has been used for the crushing of the copper ores at the "Crowned Aid" mine.
The roller crushers are classified according to the quantity of the rollers (one-roller, two-roller, three-roller, and more); according to the type of the replaceable working tools (with the smooth, corrugated, and toothed surfaces of the rollers). The major parameters, which are characterizing the roller crusher: the diameter and the length of the rollers. The diameter of the smooth rollers is by 15-20 times larger, than the maximal size of the piece of the material, which is being loaded; the diameter of the corrugated rollers is by 10 times larger, and the diameter of the toothed rollers is by 1.5-2 times larger; the length of the roller amounts to 0.3-0.7 of its diameter. The frequency of the rotation for the rollers is 50-180 revolutions per minute. The performance of the roller crusher is from 8 to 250 tonnes per hour (proportional to the frequency of the rotation for the roller, to the length of the roller, and also to the width of the output gap); the size of the pieces after the crushing depends on the type of the working tools, and on the width of the output gap. The degree of the crushing, depending on the type of the roller crushers, and on the properties of the material, is up to 4 for the hard rocks; the degree of the crushing is 6-8 for the soft and viscous rocks; the degree of the crushing is 10-12 and more (in case of the crushing within the toothed roller crushers) for the viscous clayish rocks.
Structurally, the roller crusher is most often manufactured with the rollers, which are rigidly fixated onto the shafts, which are based on the bearings, the casings of which are permanently pressed to the stops by the cylindrical springs. Between the stops and the casings of the bearings, the are installed the gaskets, which are regulating the size of the gap between the rollers. The motion of the roller crusher is provided from the electric motor. The roller crushers with one or two toothed rollers are used for the coarse crushing of limestone, marl, and chalk. There have got the greatest distribution the two-roller and three-roller crushers with the smooth and corrugated bandages for the intermediate and fine crushing. There are used the stationary roller crushers, which are installed at the ore mining enterprises, and the mobile roller crushers, which are belonging to the crushing-screening installations (Figure).
There belong to the advantages of the roller crusher the simplicity of the structure, of the maintenance, and the possibility for the crushing of the wet materials; there belong to the disadvantages the low performance, and the increased local abrasive wear of the working surfaces of the rollers. The methods for the perfecting of the structures for the roller crushers are the replacement of the cylindrical springs by the shock-absorbing pneumatic and hydraulic cylinders, and the replacement of the cogwheels within the gearbox of the electrical mover by the pneumatic tyres.
Within the USSR, there are manufactured the roller crushers of the eight standard sizes, with the smooth and corrugated rollers, with the diameters from 600 to 1500 millimetres, and with the lengths from 125 to 600 millimetres, with the performance of up to 85 tonnes per hour. The three-roller crushers, which are issued within the USA, have the rollers with the diameter of 762-1397 millimetres, and with the length of 559-914 millimetres. There are known also the four-roller crushers with two pairs of the rollers with the different diameters; there are known the roller-jaw crushers with one and two jaws, which have got the lesser distribution.
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