Screening is an indispensable unit process for separation of materials. Large vibrating screen is extensively used in coal processing because of its large production capacity. In this study, a novel large vibrating screen with duplex statically indeterminate mesh beam structure (VSDSIMBS) was presented. The dynamic model of VSDSIMBS was proposed, and characteristic parameters were obtained by theoretical calculations. In order to obtain more reliable and believable research results, model of a traditional vibrating screen (TVS) with the same mass was also established for comparisons with VSDSIMBS. The finite element (FE) method was applied to study the performance of VSDSIMBS and FE analysis of VSDSIMBS and TVS was completed by using characteristic parameters. Modal analysis results indicated that VSDSIMBS could avoid the resonance and run more smoothly than TVS. Furthermore, harmonic response analysis results showed that VSDSIMBS could improve the entire stress distribution, reduce high stress areas, and increase the strength of vibrating screen. With DSIMBS, the maximum stress of vibrating screen decreased from 130.53 to 64.54 MPa. The full-scale experimental tests were performed to validate the credibility and accuracy of FE analysis results. The stress and displacements of VSDSIMBS were measured under working conditions. The test results obtained are in good agreement with simulation results, and accord with conclusions made from FE analysis.

Flip-flow screen is a key equipment for dry screening of wet fine coal, and its working load is of great significance to the screening effect and reliability. In order to obtain material mass load characteristics of a crank-link type flip-flow screen in the screening process, a vibration-test-based method is proposed. A complete dynamic model of the crank-link type flip-flow screen system is established by the centralized mass method. The correlation between the material mass and the kinematic parameters is deduced by dynamic theory analysis. The time-frequency analysis, envelope analysis, and Kolmogorov–Smirnov test are used to analyze the material mass statistical distribution characteristics during the screening process. Also, in the vibration tests at different rotation speeds, the relation between the parameters of the material distribution model and the rotational speed is obtained by the least square method. The results of the field experiment show that the maximum deviation of this method is 6.7%, and the material mass distribution model established by this method can well reflect the working state of the flip-flow screen.

The vibrating screen with statically indeterminate mesh beam structure (VSSIMBS) is a novel type of large vibrating screen, which is widely used in coal preparation plants due to its high strength and processing capacity. In this study, the VSSIMBS motion differential equations were obtained via on Lagrange equation, and the dynamic vibration system model was established. The eccentric block force conditions during the operation were analyzed, and the stable vibrating screen operational conditions were obtained. The electromechanical coupling simulation model of VSSIMBS was built in Simulink, allowing frequency control and vibration synchronization experiments. Experimental frequency control results have shown that when the output characteristics of both motors are either the same or similar, synchronous movement can be achieved. Regarding vibration synchronization, experiment results have shown that when two motors are in synchronous motion, and the power supply of one motor is cut off, they still can operate synchronously. Thus, the experimental results obtained in this study provide a theoretical reference for improving the motion stability of large vibrating screens.

The four-axis variable trajectory equal-thickness screen (FAVTETS) achieves equal-thickness screening by appropriate excitation force generated by four eccentric rotors in synchronized motion. The forced synchronization exciter is characterized by an unsatisfactory synchronization effect due to the wear of transmission parts. Hence, in this paper, the four-axis controlled synchronization of FAVTETS is investigated, and an intelligent control system is proposed. Firstly, research is conducted on the variable trajectory characteristics of FAVTETS. Next, the sliding mode, fuzzy, and PID controllers are designed and compared to obtain an ideal control effect. Moreover, the influence of torsional stiffness of flexible coupling on control accuracy is considered. The results show that the sliding mode controller has a good control effect. Based on the aforementioned, the simulation model of a four-axis controlled synchronization structure is established via MATLAB/Simulink. Finally, Labview is employed to design the four-axis controlled synchronization software system. Then, the physical experiment is carried out. The four-axis controlled synchronization and vibration trajectory measurement results verify the effectiveness and robustness of the intelligent control system.

The double-deck vibrating flip-flow screen is taken as the study case, and the dynamic equations, including cubic nonlinear stiffness, are established. The equation in the physical coordinates is transferred to the modal coordinates to study the nonlinear vibration characteristics of the system in resonance, which is analyzed by the multi-scale method. Then, the amplitude-frequency tuning parameter response equation is obtained. The influence of system parameters on the nonlinear system is discussed by solving the amplitude-frequency tuning parameter response equation. It is found that increasing the damping or reducing the harmonic force will suppress the system’s multiple solutions and vibration jumps. Numerical methods are adopted to verify the accuracy of the perturbed solution in both the frequency domain and time domain. Considering that the nonlinear stiffness has little influence in the slightly distant single-valued response resonance region, the displacement response of the double-deck vibrating flip-flow screen in the original physical coordinates system is obtained based on the superposition principle. The amplitude of the main screen frame is 7 mm, and the amplitude of the upper and lower floating frame is 9.4 mm and 5.6 mm, respectively. The phase between the main screen frame and the upper and lower floating frame is 180°, which realizes the stretching and slackening of the deck. This paper guides the design of double-deck vibrating flip-flow screens.