Design And Kinematics Analysis Of A 2-PRRU+PRR Parallel Feed Screening Machine

With the improvement of people’s living standards,contradiction between increasing demand for livestock products and backward production has gradually become prominent.As the basic raw material of animal husbandry industry,production quality of feed has a key influence on whether it can produce high-quality products.However,with the limitation by single-degree-of-freedom screening of traditional screening machinery,screening efficiency of feed particles is low.How to design an efficient feed screening machine has become a major problem in this field.In order to improve the screening efficiency of traditional single degree-offreedom(DOF)feed sieving machine,a new weakly-coupled of 2-PRRU+PRR type parallel feed sieving machine was proposed,which kinematics and screening characteristics were studied.The main work done is as follows:1.Determine the movement form of screen.Taking the sieving motion form of screen as research object,sieving efficiency of feed in form of single DOF,two DOF and three DOF of screen is obtained by EDEM simulation.Taking the screening efficiency as evaluation index,preferred screening movement form of the screen is(x,y,y).2.Determine the main parallel mechanism.In order to make screen output the designated movement form,three kinds main body parallel mechanisms of sieving machine are proposed according to the theory of mechanism topology.By comparing the DOF,number of driving pairs and coupling degree of each mechanism,2-PRRU+PRR type parallel mechanism is preferred as the main parallel mechanism of feed screening machine.3.Kinematics analysis of main body parallel mechanism.Taking the 2-PRRU+PRR main body parallel mechanism as research object,position analysis is obtained by analytical method,and the correctness of position analysis is verified by Matlab simulation.Through the Jacobian criterion analysis,mechanism control decoupling characteristics and singular configuration are obtained.Speed and acceleration curves are drawn using Adams simulation.Analysis results show that the established kinematics model is correct,and kinematics characteristics of 2-PRRU+PRR main body parallel mechanism are conducive to screening of feed.4.Drawing and optimization of accessible workspace for main parallel mechanism.Taking the 2-PRRU+PRR main body parallel mechanism as research object,based on positive kinematics solution,the accessible workspace of mechanism is initially established.Taking the number of spatial point sets as optimization object,the quantum particle swarm algorithm is used for optimization.With the number of spatial point sets expanded by 24 times,workspace of mechanism after optimization is expanded.5.Parallel feed screening prototype test.Taking the 2-PRRU+PRR parallel feed screening machine as research object,complete design,processing and assembly of prototype.The 6-factor and 4-level test scheme was completed by orthogonal experiment method,according to EDEM simulation,the optimal test scheme was determined.And the optimal test plan is determined through EDEM simulation and experiment.Based on optimal test plan,the screening efficiency and horizontal effect of factors are studied.Test and simulation results show that screening efficiency of 3-DOF sieving motion is much higher than the screening efficiency of single DOF sieving motion.It’s proved to be feasible that feed screening efficiency increases by the increase of screen’s DOF.According to optimal test scheme factor level,the screening efficiency of feed increases first and then decreases with the increase of x-direction moving frequency,ydirection moving frequency and x-direction moving amplitude,decreases with the increase of y-direction moving amplitude and y-direction rotating amplitude,and increases with the increase of z-direction moving frequency.