Dynamics Analysis Of Large Vibrating Screen And Vibration Control

The three bodies cantilever environmental vibrating screen is an advanced screening equipment. The screen box with a modular design is divided into two modules:the vibrating box and screen. Although the efficiency of vibrating and the speed of maintenance can be improved through this design, the structure was more complicated and the dynamic characteristics were lead to be essentially different with previous vibrating screen. In this paper, the model of three-body vibrating screen was studied. The rigid body dynamic performance of vibrating screen, the elastic dynamic performance of screen box and the dynamic performance of the cantilever screening bar beams were systematically analyzed and the screen box elastic stress sensitivity formula was derived based on the dynamic response. Meanwhile, the isolation effect and vibration control of the vibrating screen in the operation and shutdown process were systematically studied according to the working conditions of the vibrating screen. Details are as follows:First, the dynamic equation of vibrating screen was established, and the displacement response formula of the vibrating body was obtained through the analysis of the dynamic equation. In order to verify the correctness of the formula and research the operating condition of vibrating screen, the simulation prototype was established in the ADAMS, and the vibrating bodies’displacement response curve was obtained through the simulation of start-running and running-stop processes. The correctness of the three-body displacement response formula of the vibrating screen was verified by the simulation results.Secondly, in order to do further study about the overall dynamic performance of the vibrating screen, the three-body dynamics parameters of vibrating screen was extracted through the joint use of ADAMS and ANSYS, and the spring-particle finite element model was established in ANSYS.Third, the dynamic characteristics of the vibrating box and screen were lead to be essentially different with previous vibrating screen due to the modular design of the vibrating box and screen. In order to analyze the dynamic performance of the vibrating box and screen, modal analysis and harmonic response analysis were done. The modal parameters of the vibrating box and screen were extracted and the weak parts were found through the modal analysis. The data of the dynamic performance were obtained through harmonic response analysis, which visually display the screening box casing and screen elastic strain, elastic stress and large stress parts.Fourth, the cantilever screen mesh sieve bar beam was the key component to complete screening, and its unique dynamic performance was caused by its peculiar structure. The dynamics equation of cantilever mesh bar beam was established in this paper, on the basis of the equation, the "frequency veering" phenomenon which was existed in the modal analysis was analyzed, and the root cause of the phenomenon of "frequency veering" was discussed. At the same time, on the basis of the "secondary vibration" dynamics analytic expression, the dynamic mechanism was analyzed, and the validity of the inference was verified through the flexible body dynamic simulation.Fifth, the vibrating screen frame is an important structure of the vibrating screen box. In this paper the relative thickness in strain sensitivity of the screen box was deduced based on dynamic response theory and substructure method, then the data was extracted using finite element technology, and the calculation of the sensitivity of the screen box was done to research the influence of its geometric parameters on the kinetics characteristics of screen box. The best parameters for the further dynamic optimizing were found.Sixth, the force transmission efficiency of the secondary vibration isolation was systematically studied according the structural characteristics of the three-body vibrating screen. The analysis result shows an excellent isolation effect. The correlations between individual responses of the vibrating screen were analyzed for the research of the stability problems of the vibrating screen during the shutdown process. The results show the three bodies of vibrating screen only coupling weak effect. The vibration in X-direction is mainly affected by the impact of the X-direction and the effects of other directions were smaller. The vibrations in Y and Z direction had the same characteristics.The innovation of this paper is that:The rigid body dynamic analysis and elastic dynamic analysis were interrelated to form a set of systematic methods of rigid body dynamic analysis and elastic dynamic analysis of multi-body vibrating screen. The dynamic analysis and vibration control methods and theories of large multi-body vibrating screen were established, which provided an effective approach for large vibration equipment dynamic analysis and vibration control. The formula of the sensitivity of the vibrating screen acting on the design parameters was obtained based on the mechanical theory of structural dynamic response. The dynamical model of the cantilever-screening-bar beam was established for the unique structure of cantilever-screening-bar beam, and the "frequency veering" theory of the cantilever screening bar beam was explained. The method of solving the vibration control problems of the normal operating conditions and shutdown process of the vibrating screen was put forward.