Study On Vibration Characteristics Of Double Body High Frequency Vibrating Screen And Material Movement

Vibrating screening is a mechanized material screening method,which is widely used in many fields such as mining,tobacco,and crop processing.Therefore,research on the vibration characteristics,fatigue life,and screening efficiency of vibrating screening equipment is particularly important.This paper mainly focuses on the research of dual-mass high-frequency vibrating screening equipment and the movement characteristics of light materials.The main research contents are as follows:A three-degree-of-freedom spring-mass model of double-mass high-frequency vibrating screen is established.The loading device is designed,and the stiffness of the vibrating spring pieces assembly are tested.The vibration differential equation of the model is established by using Lagrange equation,and the third-order natural frequency and the corresponding main mode shape of the system are obtained by numerical calculation.It is found that the working state of the system is the vibration mode dominated by the third-order main mode,and the third-order natural frequency of the system is also close to the excitation frequency of the excitation motor,which is consistent with each other.The amplitude-frequency response characteristics of the system are calculated,and the relationship between the amplitude of the vibrating screen and the exciting frequency is discussed.The finite element model for vibration analysis of dual-mass high-frequency vibrating screen is established,and the natural frequency and main vibration modes of the system are calculated.The calculated results are in good agreement with the results of the three-degree-of-freedom model,which mutually verifies the rationality and accuracy of the simplified model.Through the harmonic response analysis of this model,the changing law of system amplitude with excitation frequency is obtained,and the results are consistent with the results of three-degree-of-freedom model.Through the simulation results of three-degree-of-freedom model and finite element model,the reasons of abnormal vibration in the start-up and shutdown stages of high-frequency vibrating screen are explained,and the adaptive damping control system is designed,which effectively eliminates the severe abnormal vibration problem.The on-site vibration test of the studied double-mass high-frequency vibrating screen was carried out,and the acceleration response curves of the upper and lower masses of the system in different directions were obtained,and the system was modal tested to obtain the natural frequency and main vibration mode of the system.Through experimental data,the vibration characteristics of the system are analyzed,and compared with the calculation results of the theoretical analysis model,which verifies the rationality of the theoretical model from the experimental point of view.The movement of light materials in screening is studied.The motion equation of materials considering air resistance is established,and the judging conditions of relative sliding,relative static and throwing motion of materials are given.Through numerical simulation,the moting law of materials is obtained.The influence of air resistance,installation angle of vibrating spring,excitation frequency and seive amplitude on material movement are discussed.Based on the anti-resonance design of ideal dual-mass high-frequency vibrating screen and single-mass vibrating screen,a cantilever beam model with inertia boundary is established.By setting the displacement function in the form of space-time separation,the vibration differential equation satisfying the mixed boundary conditions of displacement and inertia is obtained by Galerkin method,and the nonlinear main resonance and harmonic resonance of the system are solved by multi-scale approach,and the amplitude-frequency response equations of the main resonance and harmonic resonance under steady motion are obtained.Through the numerical simulation results,the influence of system geometric parameters and excitation parameters on amplitude-frequency characteristics of resonance region is discussed.