Design And Analysis Of Driving Mechanism Of 2T-2R Vibrating Screen

Vibrating screen are important industrial equipment and are widely used in many industries such as agriculture and mining.As a key component of the corn combine harvester,the screening process of the vibrating screen mechanism is to stimulate the material through the screen,so that the material is subjected to delamination and through-screening,and finally a clean corn grain is obtained.In recent years,with the development and advancement of agricultural modernization,traditional screening institutions cannot meet their screening requirements,and there is an urgent need to make bold explorations of the vibrating screen's vibration form and mechanism transmission.In order to meet the cleaning requirements of modern agricultural machinery for high efficiency and high-strength,as well as the advantages of existing vibrating screens,this paper designs a type of 2T-2R vibrating screen mechanism based on the transmission characteristics of crank rocker and planar four bar mechanism.The matrix method was used to analyze the motion characteristics of each point on the screen surface,the particle motion on the screen was numerically simulated using MATLAB,and the screening performance of the 2T-2R vibration screen was studied using the CFD-DEM coupling method.The main contents and conclusions of the study are as follows:Through consulting the literature and field investigations,the basic requirements to be satisfied for the screening of vibrating screens were determined.2T-2R vibrating screen mechanism was designed by combining the transmission characteristics of the crank rocker and the planar four-bar mechanism.And the main parts of the vibrating screen mechanism such as the bar structure,the sprocket transmission and the screen face type selection were studied.The kinematics analysis of the 2T-2R vibrating screen mechanism is carried out by using the matrix method,and the position equations of the crank-rocker and plane four-bar mechanism are established,and the motion characteristics of each point on the screen surface are simulated by MATLAB.The results show that the inclination angles of the X and Y directions of the screen surface are periodically changed,and the change ranges are 0~o~4.9~o and-1.7~o~1.7~o respectively;the amplitudes of the X and Z directions of the screen surface of the 2T-2R are respectively 20mm,1.5mm;The X-axis acceleration amplitude decreases from 29.533m/s~2 to 29.087m/s~2 from the front and back of the screen surface,and the Z-axis acceleration amplitude decreases from23.754m/s~2 to 7.877m/s~2 from the front and back of the screen surface,After the increase to20.482m/s~2.the X and Z acceleration at the front end of the screen surface is larger than the rear of the screen surface,which is favorable for the material to move backward on the screen surface,The movement characteristics of the four-degrees of freedom screen surface meet the screening conditions.Based on the different movement characteristics of each point of the four-DOF vibrating screen surface,the position of the vibration direction of each point on the screen surface is different on the XOZ surface,and it is divided into four quadrants,The force analysis of the movement of a single corn grain on the screen surface was performed.Using MATLAB to numerically simulate the force of corn grain,the movement state of corn particles before each point of the screen surface was analyzed,such as slipping,moving backward and throwing up,and finally the motion state of corn grain was obeyed by a specific time step.The corn particles in the forward and backward movements collide with each other to generate chaotic motion.Choosing crank speed,transverse speed and transverse angle as experimental factors,screening efficiency and the loss rate of corn as vibrating screen sieving performance index,and obtaining the mathematical model and response surface between experimental factors and sieving performance indexes through quadratic orthogonal rotation regression test design,and determine the influence of different factors on the performance of 2T-2R vibration screening.The crank speed is the main influencing factor,followed by the transverse angle.Design-Expert software was used to optimize the experimental parameters,and the optimal combination of factors was crank speed of 270r/min,transverse frequency of 240r/min,and lateral swing angle of 1.7~o.At this time,the screening efficiency of the four-degree-of-freedom vibrating screen was 85.46%,the grain loss rate was 1.98%,and the corn grain cleanability rate was 97.03%,which satisfied the harvesting standards stipulated in the technical specifications for corn harvester quality assessment.