Design And Experimental Research Of Air Suction Picking Machine For Jujube Fruits

In order to effectively increase the output of jujube and ensure the economic benefits of farmers,the jujube in most areas of Xinjiang adopts dwarfing and dense planting mode,but this mode will limit the machine working space and passability.At present,the jujube harvesting machinery has the problems of low picking efficiency,easy damage to plants and fruits during harvesting,and difficulty in sorting jujube and impurities.Therefore,based on the material property test of the jujube,this paper used theoretical analysis,virtual simulation and test verification to carry out the whole machine design and research testing.The main research contents and conclusions were as follows:(1)Determination of the material properties of the jujube.Choosing gray jujube and Junzao as test samples,and measuring their geometric characteristics,it was concluded that the short diameter accounted for about two-thirds of the longitudinal diameter,which could simplify the jujube into ellipsoid model.The compression performance test was carried out on the jujube.The results showed that:Junzao and Huizao showed brittleness,no significant yield stage,and had anisotropic characteristics 44.87 N and 78.13 N,respectively,the average longitudinal rupture force was 77.10 N and 104.77 N,respectively.(2)The overall structure and key parts design of air suction picking machine for jujube fruits.According to agronomic requirements and previous theoretical research and analysis,an air suction picking machine for jujube fruits was designed.The overall structure of the jujube picker was described,and its working principle was introduced.The structural design analysis and calculation of key component conveying pipes,suction chambers,star wheel sorting devices,separation screens,and fan selection were performed to obtain the diameter and size range of the conveying pipes.The diameter of the conveying pipes was φ75～195 mm,the diameter of the outlet of the suction chamber was φ120～240 mm,and determined the fan model was 4-79No-3.5A and the rotation speed of the fan was selected in the range of 2500～3500 r/min.The structural design and motion analysis of the vibration separation screen were focused on,and the dynamic model of the mechanism was established.It could be obtained that its eccentricity was 60 mm and the crank rotation speed was 131.61～160.62 r/min.The characteristic value k was 1.16～1.73.(3)Fluid simulation analysis and experimental verification of the conveying device.Using Fluent software to perform gas flow velocity and pressure simulation analysis on the conveying pipeline and the suction chamber,it could be further obtained that the diameter of the conveying pipeline ranged from φ105～165 mm,and the outlet diameter of the suction chamber ranged from φ150～210 mm;The verification experimental result showed that when the diameter of the conveying pipe was φ165 mm,the diameter of the outlet of the suction chamber was φ200 mm,and the speed of the fan was 3300 r/min,the conveying amount of jujube was 238.68 kg/h,and the breakage rate was 2.18%.The errors between the field experiment value and the predicted value obtained by the software were less than 5%.(4)Prototype development and field performance experimental verification.The design data was optimized by Design-Expert sofrware,and conducting field experiment verification,final experimental results:when the parameter combination of the conveying pipe moving speed was 0.60 m/s,the fan speed was 3200 r/min,and the crank speed was 140 r/min,the experimental result was that the pick up rate of the machine was 96.41%,The miscellaneous rate was 1.67%.The error between the field experiment value and the predicted value obtained by the software was less than 5%.