Study On Key Technologies Of Potato Joint Harvest And Primary Classification In Hilly Mountainous Areas

China is a major potato producer.In recent years,the planting area and output of potatoes rank first in the world.However,as one of the important potato producing areas in China,there are still some problems such as high labor intensity and low mechanization rate in potato harvesting and grading.In order to improve the mechanization level of potato production in hilly and mountainous areas,this paper mainly carried out the research on the key technologies of potato joint harvest,primary selection and classification in hilly and mountainous areas.（1）A crawler self-propelled potato harvester based on combined harvest is designed;The design structure,function and technical requirements of potato harvester were determined by investigating the potato single ridge and double row planting agronomy in the hilly and mountainous areas of Southern Ningxia;The harvester is mainly composed of crawler chassis,digging shovel,wave lifting chain and potato collecting box.It can complete potato excavation,potato soil separation,lifting,transportation and potato collecting at one time.The supporting power is 75k W;By analyzing the stress of the mixture of digging shovel and potato soil,a plane single digging shovel is designed,and its inclination angle is determined to be 21.5°;By analyzing the movement characteristics of potato on the chain rod,a wave lifting chain was designed,and its lifting angle was determined to be 25°.（2）A mechanical roller potato grading device based on the steepest descent line was designed;By measuring the triaxial dimensions of 200 potatoes,the potato thickness of 50mm was determined as the two-level classification standard;In order to improve the accuracy of potato grading,the mechanical rollers were designed to be arranged according to the fastest descent line;The structure of the grading device is mainly composed of drive motor,mechanical roller,transmission chain and frame.The gap between all mechanical rollers is50mm.The drive motor drives the mechanical roller group to rotate at a constant speed with the help of the transmission chain.The two-stage potatoes are separated from the roller gap and the end of the roller respectively;By analyzing the stress of potato and mechanical roller,a double row sprocket roller was designed and its diameter was determined to be 50mm.（3）The finite element analysis of digging shovel of potato harvester was completed;With the help of ANSYS 2020 software,according to the steps of importing the shovel model,defining materials,dividing grids,adding constraints and calculating solutions,the maximum stress of the shovel is 31.491MPa,which is far less than the yield strength of its material 65Mn430MPa,and the maximum strain is 1.5797×10^-4,the total deformation is 0.81716mm,which is far less than the shovel thickness,indicating that the structural design of the excavation shovel meets the safety requirements;The discrete element simulation of potato grading process was also completed;With the help of EDEM 2020 software,the steps such as importing potato and the model of the steepest drop line classification device,adding roller motion,building a particle factory and calculating and solving are carried out in turn,and the accuracy of the steepest drop line simulation classification is 89.5%,which is better than that of the oblique straight line simulation classification of 81.5%.（4）The operation quality of the potato harvester was verified by the harvest experiment in the potato field in Xiji hilly and mountainous area of Ningxia;Five repeated tests were carried out according to the standard test method.The results showed that the potato harvester had a bright potato rate of 98.54%,a broken skin rate of 1.51%and a damaged potato rate of1.31%,which were better than the quality evaluation requirements of the potato harvester;The grading effect of potato grading device was verified by grading test in laboratory;The three factor and three-level experiment with the number of rollers,roller speed,potato flow influencing factors and potato classification accuracy as the evaluation indexes was completed.Through response surface analysis,the optimal classification accuracy was predicted to be93.49%,and the actual classification accuracy of the validation test was 92.5%,and the error was within a reasonable range to achieve the two-level classification goal.In this paper,the key technologies of potato joint harvest and primary selection and classification in hilly and mountainous areas have been studied.A crawler self-propelled potato harvester has been designed and the harvest test has been completed.The potato harvest quality is better than the relevant requirements.At the same time,a mechanical roller potato classification device has been designed and the classification test has been completed.The potato classification accuracy has been improved,which provides a reference for the future research on the potato harvest and classification machine.