Exchange rate in autocad by machines for production

Contents

1. Introduction

2. Roll crusher design

3. Determination of gripping angle and relation between

the diameter of the roll and the size of the incoming piece

4. Determination of roller crusher capacity

5. Determination of roll revolutions

6. Determination of the capacity consumed by the roller crusher

7. Determination of forces in parts of roller crusher

8. Peculiarity of roller crusher operation and its devices

9. Safety precautions

10. Literature

1. Introduction

Roller crushers are widely used in the construction materials industry, especially in the grinding of viscous and wet materials.

The process of grinding materials is usually divided into two stages: crushing and grinding. In turn, the crushing processes, depending on the size of the starting piece or the size of the intermediate product, are divided into large, medium and small crushing.

Methods of grinding materials are diverse. Grinding can be carried out by crushing, abrasion, fracture, impact, splitting.

The roll crusher is operated by a crush method. When crushed, a piece of material is clamped between the two surfaces and crushed with a relatively slow increase in pressure. Roller crushers are also used for secondary crushing of solid rocks (limestone, coal, various ores, etc.)

The working element in the roller crusher is two cylinders (rolls) rotating on horizontal axes towards each other and extended by a distance determined by the maximum size of the output product. The material to be crushed is fed from above, tightened between the rolls or roll and the lining of the crushing chamber, and thereby crushed.

By design, roll crushers are one-, two- and four-roll. In the latter case, one pair of rolls is positioned above the other, i.e., a four-roll crusher can be considered as two two-roll crushers mounted in one body.

The surfaces of the rolls are smooth, corrugated, ribbed and toothed. Combinations of crushing surfaces can be different: for example, both rolls can have a smooth surface, or one smooth, the other corrugated, etc.

With the same diameter, the corrugated and toothed rolls can grip larger pieces of material than smooth ones.

Industrial roll crushers have a roll diameter of 400-1500 mm and a length of 0.4-1.0 diameter (the length of the toothed rolls can be greater than the diameter).

Roller crushers are used for medium and fine crushing of materials mainly of medium strength.

In the construction materials industry, two-roll crushers are most common. Such crushers are particularly useful for grinding wet and viscous materials (for example, clays), since other crushing machines are clogged with similar materials, and special staples can be installed on roller crushers to remove sticky material from the surface of the rolls.

Roll crushers are classified according to the following three features:

according to the roll installation method: crushers with one pair of movable and another pair of fixed bearings; crusher with movable bearings;

according to the design of the rolls: crushers with toothed rolls; crushers with ribbed rolls; crushers with smooth rolls; according to the principle of action: roller crushers operating by crushing; roller crushers, in which crushing is combined with abrasion, splitting or tearing and partially impact.

The capacity of roll crushers varies from 5 to 100 t/h or more depending on the size of the rolls, the number of their revolutions and the type of material being ground.

Marble is carbonate rock, cross-stylized limestone or dolomite. The forming mineral is calcite or dolomite, respectively. Crystal rock with a massive texture. Grain size depends on the metamorphism zone: the higher the recrystallization temperature, the larger the crystals. The color of the rock is different, depends on the purity of the starting material (pure limestone gives white marble) and the composition of the impurities. This finishing and crafting material. Having a low hardness - 3-3.5 - is easily treated. Not electrically conductive and used as an electrically insulating material.

2. Design of roller crushers.

Crushers with one movable roll are most common. In almost all existing roll crusher designs, one of the rolls is installed in movable bearings sliding along the guides. Bearings are held in place by springs compressed by special bolts. In case of ingress of foreign objects, the spring under the increasing load gives a precipitate, the gap between the rolls increases and the foreign body falls out of the crusher. Then, under the action of springs, the bearings with the roll return to the initial position.

In crushers with movable bearings, both pairs of bearings are movable, abut against springs, and therefore, when foreign objects get in, both rolls move apart and pass foreign bodies. Since the rollers diverge in the opposite direction at the same speed, and inertia forces resulting from the movement of the rollers are mutually balanced, crushers of this type work relatively calmly and are called balanced. However, this type of crusher, due to the complexity of the design and the high cost, has not been widely used.

Crusher rolls are driven by electric motor (or transmission) through belt gear. In the presence of a gear, the teeth of the second pair are made elongated in height so that engagement can be achieved when the movable roll is withdrawn.

Toothed roll crushers are intended mainly for medium grinding of various rocks. They serve for the preliminary grinding of shale or particularly dense clays, as well as for the grinding of brittle materials. Rolls of crushers of this type consist of a cast-iron body (hub), on the outer surface of which a working jacket with teeth is fixed. The jacket is typically made of hardened cast iron, carbon or manganese steel and may be integral or composed of segments. In a number of structures, the working surface is composed of separate rings cast together with teeth.

The circumferential speed of the crusher rolls is generally 2-3 m/s. In differential type toothed rollers, one of the rollers rotates at a speed of 0.3-0.4 m/s, and the second - 1.2-1.5 m/s. The width of the rolls is on average 0.5-0.7 of the diameter of the shaft.

In crushers with ribbed rolls, instead of teeth, there are longitudinal ribs on the working surface.

In the industry of building materials, the so-called disintegrator rolls for grinding clays and removing stones have become widespread. The advantage of these crushers is the effective crushing of clay by impact, crushing and tearing while partially removing solid inclusions in the form of stones and other foreign objects.

In the construction materials industry, roller crushers are used mainly for grinding viscous materials. At the same time, their crushing occurs in two stages: preliminary fine crushing, in which the gap between the rolls is 8-10 mm; final fine crushing - the gap is 2-3 mm. The circumferential velocity of rolls of crushers of this type is 1.3-1.5 m/s.

The group of roller crushers also includes the so-called single-roll crushers used in cement plants for grinding viscous rocks of medium and low hardness. The presence of rods and springs eliminates the possibility of breakage of the crusher when foreign objects get into it. The degree of grinding in crushers of this type reaches 15 or more. The roll is equipped with teeth of various heights: higher teeth capture and crush large pieces, and teeth of smaller sizes crush the material to the required size .

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