The vibration of mineral sizers affects the stability of crusher operation, so their vibration problems must be investigated. Firstly, the theoretical model of the crushing roll was established based on the common rigid disc model, elastic shaft model and elastic support model in the rotor system; and the equations of motion were obtained. Secondly, the finite element model was established in ANSYS and the modal analysis was carried out to verify the correctness of the finite element model by comparing the modal analysis results with the analytical solution. Finally, based on the operating conditions and modal analysis results, it was determined that the vibration was mainly caused by the impact of the individual tooth ring with the material.
Mineral sizers are widely used in coal mining, metallurgy, building materials and many other fields. The working principle is that two crushing rolls with roll teeth rotate in opposite directions and shear and squeeze the material by mutual meshing of the roll teeth. As the core part of the double roll crusher, the crushing roller contains the crushing teeth and other components, which are the key to the safe and reliable operation of the machine. At the same time, the transverse vibration of the crushing rolls with large span will adversely affect the shaft, bearings and other important parts and reduce their service life. Therefore, the vibration of crushing rolls should be considered to provide a theoretical basis for calculating the strength and stiffness of the equipment, the allowable vibration energy level and the structural optimization of the machine.

www.exctmach.com/products/crushing-screening/mineral-sizers.html

Finite element method modeling In order to be able to use the finite element method for the dynamic analysis of crushing rolls a finite element model must be established. In general, we describe the rotor of a rotating machine with components such as a rigid disc, an elastic shaft containing masses, and an elastic support, and divide the rotor into disc, shaft segment, and elastic support units along the direction of the axis of rotation, using nodes to connect the units and a discrete matrix description while choosing the position of each node at the center of the disc, the axis, and the bearing seat. The finite element coordinate diagram of the rotor is shown in figure 1. This coordinate system allows the axial coordinate calibration of the cross section of the rotor in any axial direction: section deflection.
1.2 Differential equations of motion for mineral sizers In this paper, the crushing roll of EXCTmineral sizers crusher is used as the object of analysis, its structure is 5 rings with 4 teeth and 5 rings are closely connected together to form a chain-like vibrating system. By considering the 5 rings as rigid discs and the main shaft as elastic axes, the crushing roll can be reduced to a model consisting of a rigid disc, an elastic shaft unit and an elastic support unit with concentrated masses connected by nodes as shown in Figure 4.
2 Dynamics analysis
2.1 Finite element model is established in solid works to build a 3D model of the crushing roll as shown in Fig. 5, set the material properties of the model: density of 7850 kg/m3 modulus of elasticity of 210 GPa, Poisson's ratio of 0.3, measure and record the rotational inertia of each tooth ring on the model of the crushing roll. A 3D mass cell MASS 21 was used to model the tooth rings rotating with the spindle.
The MASS 21 unit has three degrees of freedom of movement in the coordinate direction and three degrees of freedom of rotation around the coordinate axis, so that the mass and inertia of rotation can be set in each direction, and the system has a total of five MASS 21 mass units according to the structure of the crushing roll.
The model simplification of the Mineral sizers bearing (Figure 6) has a large impact on the solution of the dynamics properties, which can be reduced to a planar two-dimensional spring in the horizontal and vertical directions for rolling bearings. The bearing support can be simulated in ANSYS using a COMBIN 214 unit, which is a two-dimensional planar spring damping unit that can only transfer forces along the linear direction of the spring, with three axes of movement constraints at the two end nodes of the unit, and can be calibrated by setting the stiffness and damping coefficients. One COMBIN 214 unit is set in the bearing cross-section at each end of the spindle, and the support of the rolling bearing is simulated according to the actual support stiffness and damping values, with one end of each spring unit applying a fixed constraint and the other end connected to the node of the spindle.
The BEAM 188 beam cell in ANSYS can simulate various properties of spindles. It is a three-dimensional linear finite strain beam cell suitable for solving structures of beams or shafts with different cross-sections from slender to moderately thick and thin. Each BEAM 188 cell has two nodes with six degrees of freedom to simulate the vibration of the spindle in all directions.
According to the structural form of mineral sizers and combined with the idea of finite element method, the model was simplified and the finite element model was established. According to the working condition of the crusher, the main vibration form is analyzed as the third order vibration type, i.e., the vibration of the crushing roll is mainly caused by the impact effect generated by the collision between the single ring and four teeth and the material.

Strength analysis of roller teeth of mineral sizers

The introduction and advantages of sidewall belt conveyor