| The potato planting area in China is broad and the planting patterns vary greatly in different regions.The mechanized harvesting level of potato in Sichuan is low due to the limitation of geographical environment and the influence of soil stickiness.Therefore,it is of great significance to study the potato soil separation device with high screening performance and low potato damage rate for realizing the potato mechanization production in Sichuan area.In order to solve the problems of poor separation effect of potato and high rate of potato damage caused by the sticky soil in Sichuan,this thesis designed a kind of potato and soil separation device which adopts the form of "single-stage ascending transport chain + two-stage vibration adjustable".Based on the existing potato planting mode,the specific parameters of the big row and double row planting mode,the growth characteristics and soil characteristics of potato at harvest time were determined.After determining the key structure and related parameters of the tuber and soil separation device,the discrete element simulation of the tuber and soil separation process is carried out through EDEM,and the motion state of soil particles and potato particles in the tuber and soil separation process was analyzed,and it was verified that the designed lifting transport chain could meet the requirements of soil screening.Through field experiments,the influence law of each factor on the potato harvesting effect was determined,and the best parameter combination of the potato soil separation device was obtained and the field measurement was carried out.The main research contents are as follows:(1)Based on the potato test base in Mengyang Town,Pengzhou City,Sichuan Province,the data collection site and field test site were designed for this time.The investigation showed that the potato planting mode here is the large-ridge double-row planting mode and the planting variety is Xingjia 2 number.The characteristic parameters of the large-ridge double-row planting model,the potato growth characteristic parameters during the harvest period and the basic parameters of the potato chunks were measured;the measurement results of the soil parameters during the harvest period showed: soil moisture content,soil bulk density,and soil tightness within the depth range of 0-200 mm The solidity increases with the increase of depth.(2)Through preliminary experiments and analysis,the overall design scheme of the potato soil separation device is determined to be a mechanism form of "single-stage lifting chain + two-stage vibration adjustable".The structure parameters of the lift chain and the shaker are designed,and the working amplitude of the shaker is determined to be 10-50 mm.The movement characteristics of the ascending chain and potatoes in the process of potato soil separation were analyzed,and the main influencing factors and parameter ranges that affected the potato soil separation effect were determined.(3)Discrete element simulation of potato soil separation device.According to the results of the field measurement in the early stage,the physical simulation model of the potato soil separation device,the soil particles and the potato particles were established,and the potato planting ridge simulation model was established,and the simulation experiment of the potato soil separation was carried out.The test results show that during the whole harvesting process,the linear velocity of the elevator chain and the amplitude of the shaker have a greater impact on the movement speed of the soil particles and potato particles,and the designed working length of the elevator chain can meet the requirements of potato soil separation.The soil can be better sieved.(4)Field tests were carried out on the improved potato soil separation device.Firstly,through single factor experiment,the influence law of each factor on potato soil separation effect and potato quality was obtained;then,through interactive experiment,through the analysis of experimental results and parameter optimization,the best combination parameters in field harvest were determined.Finally,the field inspection test was carried out on the harvester with optimized parameters,and the harvest speed was 1.0m/s,the linear speed of the lifting chain was 1.6m/s,the amplitude of the shaker was 30 mm,and the inclination angle of the lifting chain was 22°.The rate is 98.5%,and the rate of damaged potatoes is 0.9%.The results show that it is in line with the potato harvesting operations in Sichuan’s sticky soil area,and the harvesting effect is better than the national standard. |
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