Study On Vibration Reduction Mechanism And Application Of Low Vibration Vertical Mill Based On Particle Damping

High-pressure vertical mill is an efficient grinding equipment that integrates powder grinding,selection,drying and transportation.It is widely used in energy,building materials,metallurgy,electric power and other industrial fields,with the advantages of high grinding efficiency,low energy consumption,strong drying ability,etc.However,the strong vibration impact generated in the grinding process causes great damage to the key components such as counter grinding roller,grinding disc,planetary reducer and so on,which seriously affects the service life of the equipment and the economic benefits of the enterprise.In the dissertation,the self-developed?3.6m cement vertical mill is taken as the research object,the mechanism of particle damping energy dissipation is systematically analyzed from two aspects of numerical simulation and experimental research,and a damping particle collision energy dissipation model is established.Based on the rationality of structure and stress,two types of damping devices are developed.The dynamic differential equation of vibration reduction of vertical mill system with particle damping is established,and the dynamic characteristics of the system are studied.An industrial vibration damping device for cement vertical mill was developed.The vibration damping effect of the vibration damping device and the influence of the main production and operation parameters of the vertical mill were analyzed.The main work and conclusions of the dissertation are as follows:(1)Aiming at the advantages and disadvantages of the damping and energy dissipation effects of single particle damping and mixed particle damping,the calculation method of energy loss factor characterizing the energy dissipation of particle damping collision is determined.The finite element model of collision system is established,and the influence of different factors(particle size,collision speed,material properties,etc.)on the energy loss factor of single particle collision and small particle collision between two particles are analyzed and verified by experiments.The calculation results show that under the same conditions,the energy dissipation capacity of mixed particle damping is greater than that of single particle damping,and the smaller the particle size of small particles in mixed particle damping,the more energy consumed during collision,the better the energy dissipation effect was,and the more significant the vibration reduction effect was.The higher the plasticity of small particles,the more energy consumed during collision,and the better the energy dissipation effect was.With the increase of collision speed,the energy dissipation factor increases continuously.The experimental results show that the damping of the system increases with the increase of particle filling rate,and the damping effect on the system also increases.Under the same conditions,the damping effect of mixed particle damping is better than that of single particle damping,which verifies the correctness of the mixed particle damping energy dissipation model.(2)In order to analyze the influence of particle damping vibration absorber on the structural strength of the system,a vibration absorber with reasonable structure and position is designed on the basis of making full use of the spatial structure of the vertical mill body.Static analysis is carried out on the key components of the system to obtain their stress conditions.Static characteristics of rocker arm,grinding roller,upright post,grinding disc,shell,vibration absorber,etc.are analyzed in ANSYS to meet the mechanical performance requirements of the system structure.(3)Based on the Newton's second law,the dynamic differential equation of the vertical mill system equipped with the vibration reduction device is established,and the dynamic characteristics of the low vibration vertical mill are simulated and analyzed by ANSYS and MATLAB software.The study found that with the increase of the filling rate of damping particles,the vibration damping increases gradually,and the overall vibration damping effect of the system also increases continuously,the damping effect at the first-order natural frequency f1(16.7Hz)of the system is significantly higher than that at the second-order natural frequency f2(30.9Hz).When the filling rate of the damping device is 70%?80%,the effect of the damping device on the opposite grinding mill system m1 and the vertical grinding non-grinding mill system m2 both exceed 40%,and the overall damping effect of the system is close to 50%.(4)Industrial experiments showed that the main energy distribution in the vertical mill is in the low frequency band(0?30Hz)and the main frequency(about 19Hz)is also in the low frequency band.The first-order natural frequency f1(16.7Hz)of the system is close to the main frequency,and the vibration of the main grinding roller is the main reason for the unstable random vibration of the vertical mill.Therefore,in order to reduce the vibration of the vertical mill as a whole,the vibration of the grinding roller should be mainly reduced.Among the three vertical grinding systems with different installation positions,the damping effect of the inner cone cavity damping device is the best,which reduces the longitudinal vibration of the two main grinding rollers(the vibration source of the grinding machine)by 16.04%and 41.62%.In the vertical mill,the longitudinal vibration of the shell is reduced by 25.62%,and the transverse vibration is reduced by 13.83%.Under the same working condition,the operating parameters of the low-vibration vertical mill equipped with the inner cone cavity damping device are optimal.It is found that the average output of low vibration vertical mill equipped with internal cone cavity vibration absorber is 2.07t/h higher than that of the common vertical mill under the same working condition,and increased production rate by 4.86%;the average power consumption per unit product is reduced by 2.20kWh/t,with a reduction rate of 4.36%;the average fineness of the product can be increased by 5-23m~2/kg.(5)When the low-vibration vertical cement mill is applied to large-scale preparation of steel slag wear-resistant aggregates,the equipment runs stably and reliably,the unit power consumption of the system is reduced by 2.86 kWh/t compared with that of the ordinary vertical cement mill,and the vibration of the two main rollers of the mill is reduced by 18.29%and 26.62%respectively.All properties of the prepared permeable asphalt mixture could meet the requirements of?Technical Specification for Permeable Asphalt Pavement?and are superior to limestone permeable asphalt mixture with the same gradation.The results of infrared spectrum and dynamic shear rheometer analysis showed that there is no obvious chemical reaction in the permeable mixture of steel slag asphalt,which indicates that steel slag is a kind of inert asphalt aggregate with excellent performance.