The mechanism of the broken material is analyzed and a simple calculation method of mineral sizers production capacity is established. The results show that this method is more accurate, more simple and more reasonable. The production capacity calculation formula provides a reasonable and reliable theoretical basis for the design and series development of mineral sizers, and has universal significance for its series products.
Mineral sizers is the core equipment of the crushing station, which is used to break the material to the required particle size. Compared with other types of crushing machines, it has the advantages of small size, light weight, high crushing efficiency, large feeding particle size, uniform discharging particle size, no excessive crushing of the material, easy maintenance and repair, etc. It has been widely used in continuous and semi-continuous mining technology of open pit at home and abroad. At present, there is a great demand for the equipment at home and abroad. In recent years, more than 60 sets of mineral sizers have been imported into junge coal mine, datong coal mine, yuanbaoshan coal mine, linlinhe coal mine and yiminhe coal mine, etc., and remarkable economic benefits have been achieved. Due to the high cost of introduction, it is urgent to carry out technical digestion and absorption. Production capacity is an important index of its performance. It is directly related to the selection of parameters in mineral sizers design, such as the determination of power, and is also an important basis for user selection. So how to determine its production capacity is very important. Taking mineral sizers type 1250 of junger coal block as the research object, this paper innovatively proposes a simplified calculation method of production capacity through theoretical analysis, and compares the theoretical calculation results with actual production capacity and other methods to verify the correctness of this calculation method. It provides important reference value for the design and series development of mineral sizers. The main working parts of mineral sizers are two parallel tooth rollers, each of which is arranged along the axis with a certain number of tooth rings. The material is broken by the reverse rotation of the tooth rollers. The action process of the teeth on the material can be divided into three stages: The first stage, the roller teeth in the rotating motion encounter large materials, first impact shear, and then tear, if the pieces can be bitten by the roller teeth into the second stage of crushing, otherwise the roller teeth forcibly slide along the surface of the material, by the spiral arrangement of the roller teeth force the material to flip, waiting for the next pair of teeth to continue to act. This stage is the tooth from 1'1 position to 2'-2 position. The second stage starts from the material being bitten into and ends with the first pair of teeth breaking away from the bite, showing the process of teeth moving from 2 "-2 position to 3'3 position. In this stage, the cross section contained by the two teeth gradually changes from large to minimal, and then increases. The large particle size is forced to be squeezed and cut because the containing volume is gradually smaller, and the broken material is extruded and leaked from the tooth side gap. When the first pair of teeth begin to disengage, a large number of broken materials are leaked out, and individual materials with large particle size are blocked by the splitting rod. When the teeth move to the vicinity of the splitting rod, they work together with the splitting rod to split the large material and force it out, which is the third stage of crushing. At this point, the crushing process of a pair of teeth is over. How many teeth there are on each pair of tooth rings, the same process is carried out how many times when the tooth roller runs for a week, and the cycle is repeated.
The working object of the crusher is a variety of ores, rocks and coal, etc., their physical characteristics, joint structure ever-changing, so the formula derived from pure theory is not suitable for parameter design, only based on the crushing theory of the type of crusher, through the test bench test and industrial operation practice and derived empirical formula is feasible. With the continuous development of people's production practice, the correction coefficients of various broken materials will be obtained, and the empirical formula will give more accurate results.
(1) Output calculation output as the original design parameters provided by the user, it is an important basis for determining the crusher structure and transmission parameters, must be met in the design, and to leave a certain amount of surplus.
(2) Determine the oil injection amount of the hydraulic coupling
In the case of excess of the hydraulic coupling, according to the rated torque value of the motor, find the corresponding oil injection amount on the external characteristic curve of the hydraulic coupling, and fill the oil according to the oil injection amount.
(3) The selection and adjustment of crushing roller bearings is better than the selection of double-row spherical roller bearings with oil groove in the cone hole outer ring. The bearing is easy to assemble and disassemble, and the bearing clearance can be adjusted by the tight sleeve, which eliminates the bearing failure problem caused by the bearing clearance being too large. Since the bearing clearance is directly related to the bearing bearing capacity and service life, the bearing adjustment clearance value should be specified in the instruction manual so that the user can check and adjust regularly.
(4) Sealing and lubrication design due to the poor working conditions of mineral sizers, the poor sealing of the crushing roller bearing is often the direct cause of bearing damage, so the sealing problem should cause great attention of the designer. At present, domestic and some imported crushers are mostly sealed with labyrinth or labyrinth oiling seal. From the industrial operation, it is found that the sealing effect of the sealing structure is not ideal, often there will be broken material dust into the bearing cavity, and the grease infiltration dry junction, resulting in bearing damage, directly affecting the service life of the equipment. In order to solve this problem, it can be considered to set up an automatic dry oil lubrication station, regularly and quantitatively fill the oil between the maze and the oil seal, and the excess oil is extruded through the maze, so that the dust can be prevented from entering the maze, and the lubrication of the bearing can be solved; of course, the lower part of the bearing end cover must be equipped with an oil drain hole to discharge oil regularly. If the seal is good and the bearings are lubricated with lithium based molybdenum disulfide grease, there will generally be no problems with the operation of the equipment for 6-12 months.
(5) selection of reducer
As a closed drive, the main failure form of the reducer is tooth surface fatigue. When the tooth surface fatigue calculation is passed, the bending failure strength of the gear is more abundant, and the bending strength of the gear can be checked by routine. Since the moment of inertia of the gear roller and the reducer rotating part is large when the overload occurs, the selection of the reducer should be improved by a grade, in addition, all the transmission gears on the reducer should be made of hard tooth surface freighters.
3.Mineral sizers calculation of production capacity
Production capacity is the main performance index of mineral sizers, which is directly related to the selection of various parameters in the design of crusher, and is also an important basis for users to choose the machine. It can be seen that how to determine the production capacity is very important. In the traditional formula for calculating the production capacity of roll crusher, it is generally assumed that the material passes through the gap between the two rolls at the same speed. The main structural difference between mineral sizers and traditional roll breakers is that their teeth are high and large, which directly affects the speed of the material passing through the two-roll gap and the ability to feed and discharge the material, and the gap between the rollers is much larger than the gap between the rollers of ordinary roll breakers. Therefore, it cannot simply be assumed that the speed of material passing between the two rollers in mineral sizers is the same. Therefore, this paper presents a method for calculating the production capacity of the crusher. Its basic idea is that the production capacity of the crusher is equal to the total volume of the material between the two rollers minus the volume of all the roller teeth in the unit time when the roller teeth are regarded as the material. (4) the variables in the formula are shown in formula (1), (2) and (3). The selection of k value can be borrowed from the coefficient in the empirical formula of roll crusher, k=0.4~0.6. The method is applied to the calculation of mineral sizers production capacity. The result shows that the result is close to the actual crushing capacity, indicating that the method is correct and feasible.