Basic Study On The Dynamic Characteristics And Reliability Of Large Vibrating Screen With Highspeed

Strength and stiffness problems of vibrating screen are the key factors of restricting its development towards high-speed and large-scale. Based on the point of view that restricting the elastic vibration of vibrating screen,a method of adding redundant constraints to the vibration screen beam was put forward in this paper to decrease the stress concentration and uniform the energy distribution,thus improving the strength and stiffness without changing the mass of vibration screen was ensured. This is a new idea of designing high-speed and large-scale vibration screen.Firstly,the properties of the redundant constraints beam were analyzed,and the structure of redundant constraints beam was designed based on the basic principles of mechanics of materials,of which the mass and rotational inertia were designed corresponding to the ordinary tube beam.Then the design calculation of dynamic model of the vibrating screen was done.Dynamics property of the vibrating screen with redundant constraints beam and vibrating screen with general tube beam are analyzed.Two kinds of model of the first 10 natural frequencies, mode shapes and stress response under work frequency were obtained. The results show that dynamic stress and deformation of vibrating screen with redundant constraint beam decreased significantly, and the overall stiffness and strength are improved obviously.The suppressive effect of the redundant constraints beam, which is to reduce the amplitude,was studied on from the angle of energy transfer based on the results of finite element analysis.The modal power flow analysis results from Ritz series method shows the distribution of power flow within the beam.In comparison with ordinary tube beam,the modal power flow of the redundant constraints beam is evenly distributed in each mode,fluctuates throughout the beam and has a low amplitude at the ends of the beam.As a result,the redundant constraints beam can transfer the energy of vibration to the beam ends,helping improving the service life of the side plate.A experimental study of the modal and power flow test on the beam was carried out.The natural frequencies and modal shapes obtained from the modal test corresponds to that from the finite element analysis,indicating that the method of finite element analysis are reliable and the results of test are true.The modal test shows that the energy is concentrated on the central part of the redundant constraints beam between the two attached plates but attenuates at the ends of the beam,indicating that the attached plate can restrain vibration.The power flow test indicates that the power flow of redundant constraints beam attenuates rapidly at high frequencies and moves to low frequencies,it is helpful in speeding up the vibrating screen rapidly.Finally,to make full advantage of redundant constraints beam, the number, location,thickness of attached plates and the distance between double-deck attached plates are optimized respectively.The results show that the single-deck attached plate placed in the middle of the beam suppresses the vibration effectively,the suppressive effect on the vibration increases obviously with the increasing thickness until the twice as thickness as the tube beam.The double-deck attached plates will gain a better result than the single-deck ones with double thickness by adjusting the space between the two attached plates and therefore the double-deck attached plate is a better choice.Comparing the optimized redundant constraints beam with the optimized tube beam,the steady-state response were analyzed.The paper has 69 figures, 23 tables and 174 references.