Experimental Study And Parameter Optimization Of Comb-brush Roller Type Picking Device Of Ground Jujube

Jujube is loved by the people of our country,because its rich in nutrition,sweet taste,meaning good.Xinjiang is the main production area of red dates in China,output accounted for more than 40%of the country’s total output.The jujube industry is the dominant industry in Xinjiang forestry and fruit industry,which has remarkable economic and ecological benefits.Xinjiang jujube is mainly planted in the oases around the edge of the Tarim Basin,and the planting pattern of dwarfing and dense planting is adopted.Due to its own characteristics,dates will fall to the ground naturally in the mature stage,and are picked up and harvested manually,with a very low level of mechanization.Therefore,this paper developed a comb tooth scraping brush type ground red date picking device,which provides a scheme for the ground red date harvesting in sand jujube garden.The main research and relevant conclusions of this paper are as follows:1.Planting mode investigation and material characteristic determination.Through the determination of the planting mode soil characteristics and jujube orchard’s material characteristics,the final conclusion is as follows:the jujube garden is 4 m×1.5 m(row spacing×plant spacing)wide row and dense planting mode.The soil of jujube orchard is coarse sand soil,with soil moisture content of 0.42%and density of 1379.07kg/m~3.The average size of jujube is 47.52 mm in transverse axis,33.31 mm in longitudinal axis,the average mass is 17.90g,the moisture content of jujube in harvest period is 13.70%,the density is kg/m3,the Poisson’s ratio is 0.248,and the shear modulus is 0.465 MPa.The direct contact parameters of red jujube-red jujube,red jujube-sand soil and red jujube-steel plate were measured.2.Design and finite element analysis of key components of picking up device.Designing the key components of picking up device(such as comb tooth,scraping brush roller,separation rotary screen).The force analysis on the state of the red date on the comb tooth and the rotary screen bar finally determines the structural parameters of the comb tooth scraping brush type ground red date picking device as follows:The diameter of comb tooth is 14mm,the length is 300mm,and the clearance of comb tooth is 15mm.The penetration Angle of comb tooth is 30°～33°,and the penetration depth of comb tooth is 0～40 mm.The brush hair of the scraping roller is made of PVC material,with a diameter of 1mm and a length of 15 mm.Separation rotary screen grid with undulating layout.The grid bar diameter is 8 mm,the length is 1000mm,the gap of the grid bar is 20 mm,and the relative height of the undulating grid bar is 10 mm.3.Discrete element simulation analysis of picking up process.Using EDEM software established the discrete element model of jujube and sand,and then the discrete element simulation analysis was carried out.Simulation tests were designed and field tests were carried out to verify the results.The results showed that the higher the speed of the comb,the deeper the depth of the soil,the higher the climb height of the jujube along the comb surface,the more the back soil of the comb surface.4.The prototype was trial-produced and the field experiment and parameter optimization were carried out.Complete the processing of picking up device prototype,using Design-Expert experimental design and data processing software to design Box-Behnken three factors and three levels of field test,parameter optimization,and field test verification,and finally determine the best parameter combination of picking device:When the speed of the penetration depth of the comb tooth is 15 mm,the forward speed is 0.4 m/s,and the brush roller is 22 r/min,the net picking rate of Chinese jujube is 90.8%,and the impurity rate is 5.7%.