Simulation Analysis And Experimental Study On Acceleration Characteristics Of Potato In Potato Soil Separation Unit

The potato-soil separation process is the main work link that causes potato damage in mechanized potato harvesting.The potato damage is related to the structural parameters and working parameters of the potato-soil separating device.The influence of the structural parameters and working parameters of the potato-soil separating device on the potato damage can be studied.Guide the development of new models to reduce potato damage.In the process of potato-soil separation,there is an important relationship between the potato collision acceleration and the structural parameters and working parameters of the potato-soil separation device,and it is also one of the important indicators for evaluating potato damage.In this thesis,the combination of theoretical analysis,simulation analysis and experimental research is used to analyze the motion of potatoes on the oscillating separation screen surface,the friction acceleration and collision acceleration and the crank speed,screen rod spacing,screen rod material,screen surface inclination angle.The relationship between and other factors has been studied,and the main research contents are as follows:1.Taking the 4SW-170 potato excavator as the object,the working principle of the oscillating separation screen was studied,and the displacement,velocity and acceleration formulas of the separation screen were obtained.The force analysis and acceleration analysis were carried out on the movement process of the potato on the swing separation screen.Through the force analysis when the potato is in contact with the sieve rod,the relationship between the distance between the sieve rod and the supporting force of the potato on the sieve surface is determined;through the kinematics analysis,the acceleration expression of the potato relative to the separation screen is obtained;combined with the theory Through analysis,the influence of screen rod spacing,screen rod material,crank rotation speed and screen surface inclination angle on potato collision acceleration and friction acceleration was determined.2.The virtual prototype model of the oscillating separation screen type potato-soil separation device was established,and the flexible potato was added to the virtual prototype to complete the kinematics simulation of the potato-soil separation process.The results of the virtual test analysis show that: when the inclination angle of the screen surface increases,the maximum acceleration of potatoes along the screen surface direction decreases correspondingly,and the maximum acceleration in the vertical screen surface direction reaches the peak when the screen surface inclination angle is 16°;when the crank speed gradually increases,The maximum acceleration of potato along the sieve surface and vertical to the sieve surface increased correspondingly;when the distance between the sieve bars gradually increased,the maximum acceleration of potato along the sieve surface and the maximum acceleration of the vertical sieve surface decreased correspondingly.3.The discrete element model of the oscillating separation sieve,potato and soil was established,and the discrete element simulation of the separation process of potato and soil was completed.The analysis results show that there is uncertainty in the influence of potato population effect on the acceleration along the screen surface and the vertical screen surface acceleration of potatoes,that is,when the number of potatoes increases,the maximum friction acceleration and maximum collision acceleration of potatoes sometimes increase and then decrease.Decrease the maximum friction acceleration and the maximum collision acceleration of the potato;the mass of the potato and the potato acceleration have a linear relationship,the mass of the potato increases gradually,the maximum friction acceleration gradually decreases,and the maximum collision acceleration gradually increases.4.The single pendulum friction and collision test bench was used to simulate the collision and friction between the potato and the sieve rod during the separation of potato soil,and the acceleration sensor was used to capture the acceleration generated by the impact friction between the potato and the sieve rod.The single factor test results show that: with the increase of drop height,the maximum impact friction acceleration of potato increases gradually;with the increase of potato mass,the maximum impact friction acceleration of potato gradually decreases;with the increase of rod spacing,the maximum impact friction acceleration of potato Gradually decrease;when the potato is impacted and rubbed against three screen rod materials,the maximum impact friction acceleration from large to small is: 65Mn-rubber,65Mn-plastic,65Mn;the impact friction orthogonal test of potato and a single screen rod is designed,Taking the maximum impact friction acceleration of potato as the evaluation index,the test results show that the drop height and potato quality have a very significant impact on the index,and the rod material has a significant impact on the index.Potato quality>bar material;design the orthogonal test of impact friction between potato and two sieve bars,using the maximum impact friction acceleration of potato as the evaluation index,the test results show that the drop height and potato quality have a very significant impact on the index,and the distance between the bars and rod material had a significant impact on the index.The primary and secondary order of the influence of each factor on the test index was: falling height > potato quality >rod spacing > rod material.