Analysis Of Dynamic Characteristics Of Potatoes On Swing Separation Sieve And Optimization Design Of Separation Device

The main causes of potato damage during mechanized harvesting are collision and friction.Swing separation sieve is the core component of the rod chain-swing sieve combined potato digger for potato soil separation,and its working performance directly affects the efficiency of potato soil separation and potato damage.This thesis conducts theoretical analysis,experimental research,and discrete element simulation to study the motion characteristics of potatoes on the swing separation sieve,friction force along the sieve surface direction,jumping height,separation time,and other aspects.The main research contents are as follows:1.Through the theoretical analysis of the acceleration of the swing separation sieve,the mathematical model of the acceleration of the swing separation sieve along the sieve surface is obtained.The three-dimensional acceleration sensor was used to conduct experimental research on the motion process of the swing separation sieve,and the acceleration variation law of the swing separation sieve under different crank speeds was obtained.The mathematical model of acceleration along the sieve surface was obtained by modifying the theoretical model of acceleration based on the experimental data.2.Through EDEM2020 discrete element simulation software,the virtual simulation test was carried out to obtain the influencing factors and rules of potato friction along the direction of the sieve surface.In the test range,the friction force of potato along the sieve surface is positively correlated with potato mass and falling height,and increases with the increase of potato mass and falling height.There is a quadratic positive correlation with the crank speed.With the increase of crank speed,the friction force along the sieve surface increases faster.There is a quadratic negative correlation with the angle of sieve surface.With the increase of the angle of sieve surface,the friction force of potato along the direction of sieve surface decreases slowly.Through orthogonal test,the maximum friction force of potato along the direction of the sieve surface was analyzed.From the range analysis,the main and secondary factors affecting the maximum friction force of potato along the direction of the sieve surface were as follows: falling height > crank speed > angle of the sieve surface;The maximum scheme to obtain the maximum friction force of potato along the direction of sieve surface is as follows: falling height 400 mm,crank speed 240r/min,sieve surface angle 7.7°;The minimum scheme is: falling height 100 mm,crank speed160r/min,sieve surface inclination 21.7°;According to variance analysis,the significant levels of factors affecting the maximum frictional force along the sieve surface are as follows:falling height and crank speed have extremely significant effects on the maximum frictional force along the sieve surface(p < 0.01).The angle of sieve surface had significant effect on the maximum friction force of potato along the sieve surface(0.01 < p < 0.05).3.Through the establishment of potato friction test system,the maximum friction force of potatoes along the direction of the sieve surface on the separation sieve was tested by single factor test.The test factors were potato mass,crank speed and sieve surface angle.The results show that there is a positive linear correlation between potato mass and the maximum friction force along the sieve surface,which increases with the increase of potato mass.There is a quadratic positive correlation between the crank speed and the maximum friction force along the sieve surface,and the increase rate is faster with the increase of the crank speed.There is a quadratic negative correlation between the angle of the sieve surface and the maximum friction force along the direction of the sieve surface,and it decreases slowly with the increase of the angle of the sieve surface.4.In view of the difficult balance between potato breaking rate and separation and transportation efficiency on the swing separation sieve of 4SW-170 potato digger,laboratory tests were carried out on the potato transportation and separation operation.The maximum jump height and separation time of potatoes on the swing separation sieve were used as indexes to conduct indoor single factor tests and orthogonal tests.The single factor test shows that the maximum jump height of potato on the swinging separation sieve is positively correlated with potato mass and crank speed,but negatively correlated with the distance of sieve rod and the angle of sieve surface.The separation time was positively correlated with the spacing of sieve rods,but negatively correlated with potato mass,crank speed and sieve surface angle.Sieve rod material 65Mn-rubber has better comprehensive performance under the two indexes of maximum jump height and separation time of potato.The range analysis of orthogonal test shows that the main and secondary factors affecting the maximum jump height of potato are as follows: sieve rod material > sieve rod spacing > sieve surface angle >crank speed;The main and secondary factors affecting potato separation time were as follows: inclination angle of sieve surface > spacing of sieve rod > crank speed > sieve rod material;Through the comprehensive scoring method,the optimal separation sieve parameter combination is as follows: crank speed 200r/min,sieve surface angle 21.7°,sieve rod material 65Mn-rubber,sieve rod spacing 50 mm.