Study On Potato Dropping Damage Mechanism And Damage-proof Device

In the hills and mountains of Sichuan,potato is used as fresh food,it usually harvested immediately after seedling cutting.This potato has a high moisture content and easily damaged.Its periderm damage-proof is a difficult problem for potato harvesting.It is investigated that during harvesting potato damage is mainly caused by the collision and impact between the potato and the conveyor rod of the harvester.This paper have analyzed various the factors that affects potato damage,such as potato dropped height and posture,rod size and potato varieties.By the finite element simulation and experiments,the damage mechanism about potato dropped height and its corresponding initial velocity were studied.Based on a mature harvester production,the potato damage-proof device was improved and kinematics analysis was implemented.Finally,the mechanism of potato dropped damage and the effectiveness of the damage-proof were verified through experiments.This paper originally studied potato-rod collision in potato damage.It is beneficial to improve potato harvesting quality and farmers’ economic interest.The main contents of the paper includes:1.The mechanism of potato dropped damage was discussed,and the potato-rod dropping simulation and experiment were completed.Chosen the characteristic parameters of potato.A three-dimensional solid model of the potato was established by three-dimensional scanning.The finite element method was used to simulate the drop collision between potato and rod.As it proved,the higher the drop height of potato was,the more serious the damage was.The mechanical properties of the potato test by using universal testing machine obtaining the ultimate stress value of the damage of potato.The drop-collision test was conducted on the potato-rod test bench.Combining the above simulations and tests,it was concluded that: For the potato NO.15 Netherlands,which was planted in hills and mountains of Sichuan,110 g weight,79.5% moisture contend average,and harvested in about half month,the free fall safe height is 0.3m.and the initial speed of safety collision was 2.4249 m/s.Through linear fitting,The relationship between limiting potato stress and drop height was: σ = 1.5894 h +1.0565;the relationship between maximum potato stress and initial collision velocity was σ = 0.0811v₀² + 1.0565.2.Based on the mechanism of potato dropped damage,the structural parameters design and study are carried out.According to the agronomic requirements of potato cultivation in the topography of mountainous areas in Sichuan,the working principle and overall design scheme of the potato damage-proof device were determined.According to the mechanical design principle and functional requirements of the potato damage-proof device,the frame part was designed;The mechanical and kinematic characteristics of potato in the separation phase of potato were analyzed,and a three-wheel exciter and a metal rod chain on the rod’s lift chain were designed.Based on the mechanism of potato fall damage,the relationships between parameters such as speed,amplitude,radius of rotation and linear velocity of metal rod chain with Three-wheel exciter were studied,and the key factor affecting potato damage in practical work was found to be Three-wheel exciter rotating speed;Finally,the damage prevention chain of key components of the damage-proof device was designed in detail.3.Compared with the performance of the damage-proof device and the ordinary potato harvester.Completed a single factor test of the damage-proof device.The kinematics simulations of the damage-proof device and the ordinary potato harvester were carried out using a virtual prototype.It was concluded that ordinary potato harvesting devices were more prone to damage than the damage-proof device.Through the simulation of the potato harvesting process,the potato damage rate of the ordinary potato harvester and the damage-proof devices were measured respectively.On the same harvesting conditions,the damage rate of the ordinary potato harvester was 0.0674%,and the damage-proof devices was 0.0326%.Damage-proof device has been proven to have better damage-proof than ordinary potato harvesters.Finally,by changing the speed of three wheel exciter,the single factor test of potato damage prevention device was carried out.Confirming a parameter of minimum damage rate of potato: the angular velocity of the three-wheel excitation device was 15.072 rad/s.and the linear velocity of the transport chain was 1.507m/s.