Double roll crusher introduction
Double roll crusher is one of the oldest ore crushing equipment, due to its simple construction, it is still gaining application in cement, silicate and other industrial sectors, mainly used as medium and fine crushing operation of ore. Since this crusher has the disadvantages of large floor space and low production capacity, it is rarely used in metal mines and is replaced by cone crushers. However, in small mines, or processing precious ores, the requirements of the mud is very small re-election plant (for example, tungsten ore) there is the use of roller crusher.
There are two basic types of roll crushers: double roll crusher and single roll crusher.
Double roll crusher (also called twin roll crusher) is composed of two cylindrical rollers as the main working mechanism (Figure 1). When working, the two round rollers rotate in opposite directions, and the material (ore) is crushed by the friction between the rollers, which rolls the material into the crushing cavity formed by the two rollers. The crushed product is discharged from the gap between the two rolls under the action of gravity. The size of the gap determines the maximum size of the crushed product. Double roll crushers are usually used for medium and fine crushing of materials.
A single roll crusher consists of a rotating roll and a jaw plate, also known as a jaw roll crusher. The ore is crushed between the roll and the jaw plate and then discharged through the discharge opening. This type of crusher can be used for coarse crushing of medium hardness cohesive ores.
The crushing action of the smooth roll crusher is mainly crushing, and also grinding action. This kind of crusher is mainly used for medium and fine crushing of medium-hard ores. Toothed roll crusher is mainly for splitting and grinding, which is suitable for coarse and medium crushing of brittle and soft ores.
The specification of the roll crusher is expressed by the roll diameter D x length L. The parameters of the roller crusher series produced by Henan Deya Machinery Co., Ltd.
Roll crusher series technical parameters
Double roll crusher structure
Figure 2 shows the structure of double roll (smooth surface) crusher. It is composed of crushing roll, adjusting device, spring safety device, transmission device and frame, etc.
Crushing roll: It is two rolls rotating in parallel on the horizontal shaft in opposite directions, and it is the main working mechanism of the crusher. The bearing of one of the rolls (the right one in the picture) is movable, and the bearing of the other roll is fixed. The crushing roll is composed of shaft, hub and roll surface. The roller shaft is keyed to the hub with a conical surface, and the roll surface is fixed to the hub with the help of three conical arc irons, which are held together with the use of bolts and nuts. Since the roller surface is in direct contact with the ore, it needs to be replaced from time to time, and it is generally made of high manganese steel or special carbon steel (chrome steel, chrome manganese steel, etc.) with good wear resistance.
Adjusting device: The adjusting device is used to adjust the size of the gap between the two crushing rolls (i.e. the discharge opening), which is adjusted by increasing or decreasing the number of shims between the two roller bearings, or by using the worm wheel adjusting mechanism, so as to control the size of the crushing product.
Spring safety device: It is a very important part of the roll crusher, the spring tightness has an extremely important role for the normal work of the crusher and overload protection. When the machine is working normally, the pressure of the spring should be able to balance the force generated between the two rolls to maintain the gap at the discharge port and make the product size uniform. When the crusher enters the non-crushing object, the spring should be compressed, forcing the movable crushing roller to move laterally, and the width of the discharge opening increases to ensure that the machine is not damaged. After the non-crushing object is removed, the spring returns to its original state and the machine works as usual.
During the work of the double roll crusher, the safety spring is always in a state of vibration, so the spring is easily damaged by fatigue and must be checked frequently and replaced regularly.
Transmission device: The electric motor drives the two crushing rolls to make rotating motion in opposite directions through the v-belt (or gear reduction device) and a pair of long-tooth gears. The gear is a special standard long tooth, when the crusher enters the non-crushing object, the distance between the two roll shafts will change, then the long tooth gear can still ensure the normal meshing. However, this long tooth gear is difficult to manufacture, often stuck or broken during work, gear repair is also very difficult, and the noise is large when working. Therefore, the long-tooth gear drive is mainly used for double roll crushers with low rotation speed, and the circumferential speed of the roll surface is less than 3 m/s. The crusher with higher rotation speed (circumferential speed greater than 4 m/s) often uses separate motors to drive the two rollers to rotate respectively, which requires the installation of two motors (or two sets of reduction devices), so it is more expensive.
Frame: the frame is generally made by cast iron casting, can also be made of steel sections welded or riveted, requiring the frame structure must be strong.
Double Roll crusher has developed slowly in recent years, only in the adjustment and insurance of the machine discharge port using hydraulic devices, and the emergence of multi-roller roll crusher (such as four-roller crusher). Four-roller crusher is actually a combination of two-roller crusher, composed of two rollers with equal specifications in series, and the structure is roughly the same as the smooth roller machine. This kind of roll crusher, is the use of two motors through the belt or gear reduction device to achieve the transmission of the machine.
Application & maintenance
The normal operation of a double roll crusher is determined in many ways by the degree of roll surface wearing. Only when the roller surface is in good condition, can the roll crusher obtain high production capacity and discharge qualified product size. Therefore, it is necessary to understand the factors influencing the roller surface wear and the problems to be paid attention to in the operation; check the roller surface wear regularly, repair and replace it in time if necessary.
When crushing ore, the roll surface are worn gradually. The main factors affecting the roller surface wear are: the hardness of the ore to be processed, the strength of the roller surface material, the surface shape and size of the rolls, as well as the operating conditions, the feeding method and the feed size.
The service life of the roll surface and the process index of the roll work depend on the uniformity of the distribution of the ore (material) along the entire length of the roll. If the material is not evenly distributed, the roller surface not only wear out quickly, but also appear ring grooves, resulting in uneven size of the crushed product.
Therefore, except for the coarse crushing single roll crusher, all roll crushers are equipped with an ore feeder, the length of which should be equal to the length of the rolls to ensure uniform ore feeding along the length of the rolls. At the same time, in order to feed the ore continuously, the rotation speed of the feeder should be faster than the rotation speed of the rolls, about 1-3 times faster. In the operation of the roll crusher, also pay attention to the ore feeding size, if it is too large, it will produce violent impact, the roller surface wear is serious, especially significant when coarse crushing.
In order to eliminate the uneven wear of the roller surface, when the crusher is in operation, constant attention should be paid to the size of the crushed product, and one of the rollers should be moved along the axial direction once in a certain period of time, the distance moved is approximately equal to 1/3 of the feed ore size.
When the crushing ratio needs to be changed and the rolls are moved, the rolls must be made to move parallel to prevent the rolls from being skewed, otherwise it will lead to rapid and uneven wear of the roll surface, and in serious cases, it will cause accidents.
Roller crusher is dusty when working, it must be equipped with an airtight safety cover. An entry hole (inspection hole) should be left above the cover to check the wear condition of the machine rolls.
It must be noted that during the operation of the roll crusher, the safety operation procedures should be strictly observed to prevent personal accidents caused by involving the hands in the rolls.
In order to ensure the normal operation of the roll crusher, attention should be paid to the lubrication of the machine. Sliding bearing lubrication can be used to regularly inject thin oil or oil cup refueling method; rolling bearing lubrication can use the oil injector (or pressure oil injector) to inject thick oil method.