| Jujube has a very high nutritional and medicinal value,and has a long history of cultivation in China,which also is one of the characteristic forest fruits of large area at the same time.At present,the planting area of jujube accounts for more than 99% of the world.In recent years,the planting area of Xinjiang jujube has been growing continuously.Artificial gathering the jujube has a low efficiency and high cost,which is unable to meet the needs of the rapid development of the jujube industry,so it is urgent to develop the mechanized pickup machine for the ground jujube.This paper is based on the research and analysis of the development status of mechanical and pneumatic picking devices of fruits at ground surface.It is aimed at this problems that the mechanical fruit picking device with high rate of injury and high requirements for ground flatness;the pneumatic type red jujube picking device is easy to block and absorb jujube,and combined with the advantage of low rate of injuried jujube in air-suction floor jujube picking device;proposing an air-blowing floor jujube picking method and designing an air-blowing floor jujube picking device to improve the picking efficiency of landing jujube and reducing Jujube damage,reduce power consumption,enhance the device's adaptability to the ground.The main research contents of this paper are as follows:(1)Research on the planting pattern of jujube with dwarf and dense planting and its material characteristics test.The research results showed that the tree spacing of jujube with the dwarf and dense planting pattern was 3201.5 mm,the row spacing was 1537.5 mm,the minimum height of jujube was 401.5 mm,and the minimum height of 74.4% jujube is less than 450 mm.In the harvest period,the average rolling resistance coefficient between the jujube and jujube ground was 9.14;For the jujube in harvest,the average vertical axis diameter,transverse axis diameter,single grain weight,surface hardness and wind pressure of suspension of single grained jujube was 29.27 mm,41.21 mm,9.76 g,810000 Pa and 459.51 Pa,respectively.(2)The design of jujube pickup device with air blowing type.This paper described the principle and structure of the whole device,and the air distribution device and the conveying device were also designed.At the same time,the structural analysis of the key components of the pickup device was completed.The transmission system of the pickup device with air blowing type was designed according to the requirements.(3)Air Distribution Device Adams Simulation Analysis.Through Adams kinematics simulation,the speed of the air distribution device was matched at different forward speeds.The forward speed of the complete machine is 0.3 m/s,0.4 m/s,0.5 m/s,0.6 m/s,0.7 m/s,0.8 m/s,0.9 m/s,and 1.0 m/s,respectively.The corresponding rotational angular speed ranges are 2.79~5.86 rad/s,3.72~7.82 rad/s,4.64~9.34 rad/s,5.58~9.91 rad/s,6.54~10.91 rad/s,and 7.43~12.95 rad/,respectively,8.32~14.63 rad/s,9.23~16.79 rad/s.(4)Air distribution device CFD simulation analysis.Through CFD simulation and analysis,when the two ends of the air distribution device are “S” shaped,they can well adapt to the gas flow,reduce the internal turbulent kinetic energy,and improve the stability of the air flow.Through CFD analysis of different gaps between the wind deflector and the rotating duct,when the clearance b is 0.5 mm,1 mm,2 mm,3 mm,and 4 mm,the inlet pressure of the airflow nozzle is reduced to 76.35%,52.79%,and 31.13% in turn.22.33%,17.52%;the airflow rate was reduced to 80.25%,63.65%,57.41%,48.18%,41.69% in turn.In order to reduce the air flow loss,reduce the cost,and ensure that the air distribution device has sufficient air pressure,the gap of 0.5 mm is selected.(5)Experimental Study on Air-blown Ground Jujube Pickup Device.The test results show that the damage rate of the jujube red jujube picking device was close to 0.When the frequency of the frequency converter is 12.2 Hz and the number of unobstructed airflow nozzles is 12,the pick-up rate is 85.7%. |
PDF Full Text Request