Research And Design Of Efficient Multi-dimensional Vibrating Screen Based On Parallel Mechanism

Vibrating screen is widely used for agricultural, chemical industry, mining and other departments, which directly influences the working performance of the machine. This paper took cleaning screen as target, researched on efficient vibrating screen on condition that airflow and type of sieve pore were neglected. Fruits of the research have a practical significance to improve the efficiency of such machines, and can be applied to agricultural, chemical industry, mining and other departments to cleaning grain or screening granular materials.Most of the current vibrating screen use of planar linkages, and their efficiencies are restricted because of screening surface moving in a plane. This paper looked on parallel mechanism as the main body of the vibrating screen, and screening efficiency improved with screening surface had multi-dimensional motion. They were two main contents of the research, one was to seeking for motion modes of the screening surface to improve screening efficiency, and the other was to analyze the main body of the multi-dimensional vibrating screen.By researching movements of grains while vibrating screen working in reciprocal and multi-dimensional motion, motion modes of screening surface which conducive to improve screening efficiency were studied with software LS-DYNA. The analytical model was established according to the structure and material characteristic of screening surface and grains. Taking effect of friction and collision of screen to grains and grain to grain into consideration, it solved out the law curve of grains' movements. On this basis, a dispersancy index was presented to analyze screening efficiency, so that three kinds of motion modes of screening surface wereobtained.This paper did the structural, kinematics, dynamics analysis and efficiency evaluation of the main body of the multi-dimensional vibrating screen. Firstly, the paper selected three kinds of parallel mechanisms based on the single open-chain element method. After analyzing the composition as well as the characteristics of structure of three mechanisms, one of the mechanisms was determined. The determined mechanism was composed of mixed branch(-P^(3R-2P)(?)-) and space branch(P-S-S), andhad a compact structure. Secondly, this paper did the kinematics, dynamics analysis of the main body. Kinematics analysis includes analyzing of forward and inverse position, velocity and acceleration. The forward and inverse position analyses were done with analytic method, and the calculations were done by programming with MATLAB to verify forward and inverse position analysis. Velocity and acceleration were first derivative and second derivative of the position. The dynamic equations of the main body were established with Lagrange method, which mainly studied three balance moments of driving forces. Thirdly, this paper evaluated screening efficiency of the multi-dimensional by simulation method. Kinematics performance of the main body was simulated with software ASAMS, as a result, the motion curves of the screening surface was gained. After solving the law curve of grains'movements of this multi-dimensional vibrating screen by using software LS-DYNA, the screening efficiency of this multi-dimensional vibrating screen was evaluated. The screening efficiency of this muti-dimensional vibrating screen was comparsed with reciprocal vibrating screen by using dispersancy index, and results show that this multi-dimensional vibrating screen has higher screening efficiency.