Design And Dynamic Optimization Of Large Double Mass Anti-resonant Vibrating Screen

At present,the vibrating screen is a kind of common construction machinery.Because of its simple operation,reliable operation and high efficiency,it has been widely developed and applied in many fields of industrial production in our country,The emergence of vibrating machinery has greatly promoted the development of industrial production,and improved the economic efficiency of enterprises.With the rapid economic development in our country,the demand for energy is also increasing,and the energy consumption is increasing greatly.The environmental problems are becoming more serious,which in turn restricts the economic development.For some traditional vibration machines,because of its high energy consumption,low efficiency and other characteristics,it has not met the current energy saving and low-carbon economic development direction in our country.In contrast,the advantages of anti-resonant vibrating machinery is more prominent,which has long service life,light weight,low noise,energy saving and environmental protection advantages,in line with China's current economic development in low carbon energy saving requirements,because of its broad development and application prospect of anti resonant vibrating machine is more and more attention.The theory of anti-resonant is applied to the design of a new type of double mass anti-resonant vibrating screen,And carry on the sufficient theory research and the performance simulation to it,mainly has carried on the following work:Firstly,the mechanical model of anti-resonant system is established.Then the dynamic response analysis is carried out to obtain the displacement response formula of the upper and lower mass.In order to study the vibration mechanism of double mass anti-resonant vibration system,the parameters of anti-resonant system are introduced,such as natural frequency ratio,mass ratio,damping ratio.The vibration system is simulated by MATLAB software,and the influence of the parameters of anti-resonant system on the amplitude of mass is obtained.The method of parameter selection is analyzed under the two conditions: "the minimum change of work amplitude at the working point" and "the minimum amplitude change near the working point".On this basis,the method of parameter optimization is determined.It provides the theoretical basis and design basis for the parameter selection of the structural design of the vibrating screen.Secondly,the cantilever screen mesh is only the upper mass.On the basis of retaining the screen structure of cantilever screen mesh,a new type of anti-resonant vibrating screen with cantilever screen mesh as its vibrating body is put forward.According to "the design code of vibrating screen " and "GBT 26506-2011 cantilever vibratory screen" to design the main structure of vibrating screen,such as cantilever screen,screen box,beam.Based on the theory of anti-resonant,the selection of some kinematic parameters and kinetic parameters is calculated in detail,and the strength of some important parts is checked by the strength criterion.According to the theory of anti-resonant and the parameter selection method,the parameters of the anti-resonant system.Aiming at the problems of connection between screen mesh and screen box,two kinds of structures are designed,which are connected by plate spring or spiral spring.Considering the plate spring has the advantages of the simple structure,strong bearing capacity,easy installation,low cost,easy maintenance and replacement,At the same time,the plate spring can play the role of guiding and transmitting the exciting force.Compared with the spiral spring,the plate spring don't need guide rod and the sleeve,and the structure is simplified.By comparing and analyzing,the plate spring is used as the main vibration spring,and a new type of anti-resonant vibrating screen is designed,whose cantilever screen mesh is a vibrating body with a plate spring as the main vibrating spring.Third,in order to study the elastic dynamic performance of double mass anti-resonant vibrating screen.The three-dimensional model is simplified and imported into ANSYS Workbench for finite element analysis,including statics analysis,modal analysis and harmonic response analysis.The static analysis obtained the static stress and static deformation of the vibrating screen.According to the material allowable static strength criterion,determine the static strength of the vibrating screen to meet the requirements.In modal analysis,the natural frequency and vibration mode of the screen box and screen are obtained.The excitation frequency 16 Hz avoids the resonance point of the structure.On the other side,there is a great gap between the two sides,normal operation can avoid resonance.In the analysis of harmonic response,the anti-resonant point is verified,and the mechanical properties of the screen box and screen mesh in resonance state are analyzed.By transient dynamic analysis,the dynamic stress and dynamic deformation of the vibrating screen underthe action of the harmonic exciting force are obtained.According to the dynamic mechanical strength criterion of vibration,the vibrating screen meets the requirements of dynamic strength.Fourth,the virtual prototype model is established by using dynamic software ADAMS,and the starting process and of the stopping process are simulated.The displacement response curve of the upper and lower body and the dynamic load change of the vibration isolation spring are obtained.The simulation results verify the correctness of the anti-resonant parameters selected and the feasibility of the application of anti-resonant theory in this design.In order to further study the stability of the vibrating screen designed,In combination with ANSYS and ADAMS for the influence of "exciting force is offset center of mass","random fluctuation of material quality ","the stiffness of main vibration spring is uneven" and "two motor speed is not synchronized " to sieving performance of vibrating screen,the simulation analysis is conducted.In the light of "two vibration characteristic " of cantilever vibratory screen,the flexible body dynamics analysis is performed.It shows that the secondary vibration of cantilever screen mesh can change the degree of sieve aperture,and the size is0.142%,which can promote the screening performance of the designed vibration sieve slightly.The modal analysis of a single screen bar shows that the excitation frequency 16 Hz is much smaller than the first order natural frequency 215.58 Hz of the screen bar.Therefore,the anti-resonant work of the vibrating screen is impractical to achieve the resonance of the screen bar.In short,a new type of double mass anti-resonant vibrating sieve is designed on the basis of the analysis of the dynamics of the double mass anti-resonant,.A cantilever screen mesh is used for the vibrating body,and it has minimize vibration mass to reduce energy consumption.Compared with the same kind of vibrating screen,the vibration quality is reduced by about 70%,the power of the motor can be reduced by 67%,and the dynamic load of the stable working foundation is reduced by about 79%.At the same time,based on the finite element analysis of the vibrating screen,the strength of the vibrating screen is determined according to the strength criterion.According to the study of the performance of the vibrating screen.Aiming at the influence of "exciting force is offset center of mass","uneven material distribution ","the stiffness of main vibration spring is uneven "and "twomotor speed is not synchronized "to working stability of vibrating screen.The simulation results show that:(1)In order to ensure the normal operation and screening effect of the screen,When installing the vibration exciter,the excitation force shall not be more than 0.05 m.(2)the vibration amplitude and vibration intensity of the vibrating screen are basically the same when the vibrating screen is added from no-load to full load,and keep good working condition.When the screen material accumulates on the side of the screen,it will increase the left and right of the screen,and the screen box will vibrate in the direction of Y.When the material accumulates at the entrance of the material,it mainly affects the eccentricity of the exciting force,and affects the location of the anti resonance point and increases the amplitude of the screen box.(3)when the screen on both sides of the spring stiffness is not uniform,will aggravate the screen in the Z direction(perpendicular to the direction of the vibration sieve box side),causing screen swings around the resonance amplitude will increase at the same time start screen box in the vertical direction.(4)when the two motor speed is not synchronous,there will be a difference in speed,?When the speed difference is small,the amplitude of vibration amplitude is close to work,take the is formed due to harmonic vibration frequencies are small superimposed on each other,the vibration strength of the material increased to a certain extent,help to improve the effect of material screening.With the increase of the speed difference,the vibration period of the beat becomes shorter,and when the speed difference is 15.6%,the beat vibration is basically eliminated,but the vibration intensity is reduced by half,and it can not meet the original work requirements.Finally,dynamic analysis was carried out about “ secondary vibration"of cantilever screen,results showed that the "two vibration" of screen bar has a promoting effect for screening performance and reduce clogging.