Design And Study On The Reciprocating Tea-roller Screen With 2DOF

Roller screen has been widely used in the field of fresh tea leaves screening.The existing roller screen rotated at one direction to perform screening.The screening efficiency mainly depends on the speed of roller,and the form of this movement is sole which lead to the limited utilization rate of the sieve and the screening efficiency.In this paper,the designed ideas of reciprocating roller screen with 2DOF was proposed,in order to optimize the roller screen movement pattern,to obtain a more superior movement form of the particles on screen surface.In this paper,the discrete element simulation software EDEM was used to carry on the numerical simulation of the screening process on roller screen,and the kinematics simulation software ADAMS was adopted to make analysis on dynamic behavior of the roller screen.The main work and the conclusion are as follows:In the numerical simulation of the screening process on roller screen with the use of EDEM,the influence of various reciprocating rotary parameters on the screening efficiency was obtained.With consideration of both the screening efficiency and processing capacity,it is founded that when the inclination is of 4° to 8°,the reciprocating frequency is of 2Hz to 2.5Hz and the reciprocating angle is of 60° to 75°,we can have the ideal screening effect.Based on EDEM,the screening process of tea-leaves in reciprocating roller screen with 2DOF was numerically simulated with 2DOF.The screening process of the roller screen which was exerted linear reciprocating vibration in three direction of X,Y and Z was simulated respectively when the screen was under reciprocating rotary motion at the reciprocating frequency of 1.5Hz.It is founded that the linear reciprocating vibration in X-direction helps greatly to promote the dispersion,penetration and conveying of the particles on the screen.Then the orthogonal test was used to arrange the simulation under the 2DOF-vibration mode that combined linear reciprocating vibration in X-direction with reciprocating rotary motion,and it comes to the conclusions that the excitation frequency and reciprocating angle both have a significant effect on the clean sifting rate when the reciprocating frequency is of 1.5Hz.Furthermore,we obtain that the optimal screening scheme is that the excitation frequency is of 8Hz,amplitude is of 8mm,reciprocating angle is of 70° under the reciprocating motion when the reciprocating frequency is of 1.5Hz and inclination is of 6°.The parallel excitation mechanism with good decoupling performance is designed,which can meet the requirements of linear reciprocating vibration in X-direction.Then the ADAMS was applied to develop the dynamic behavior simulation of the roller screen,and the motion behavior under diffrent parameters of the reciprocating roller screen with 2DOF are accessed.Combining with the particles movement rules obtained by the simulation in EDEM,the movement and screening mechanism of the tea-leaves particles on the reciprocating roller screen with 2DOF are further revealed.Finally,fresh tea-leaves screening experiment was done on the homemade reciprocating roller screen,and it verify the influence laws of reciprocating rotary parameters on screening efficiency through the simulation in EDEM.It conclude that the best screening occurred when the reciprocating frequency is of 2.5Hz and the reciprocating angle is of 100°.