Design And Experimental Research Of Air-blowing And Vibrating Supply Seed Tray For Precision Seeding Device

With the development of super rice planting technology,the planting area of super rice has continued to expand,and the planting requirements of super rice planting equipment with 1～2 grains/hole and low damage rate are also put forward.Domestic and foreign studies on rice precision seedling raising equipment show that the vacuumvibration tray seed metering device has the advantages of low seed damage rate,high seeding efficiency and high seeding precision in the process of rice cultivation.Therefore,it also has a good application prospect in precision seeding of super rice.In order to meet the agronomic requirements of super rice precision seeding,the research team designed the vacuum-vibration tray precision seeder in the early stage.The seeder has basically met the agronomic requirements of super rice precision seeding in a short work time,but it vibrates the seed population with a high-frequency mechanical vibration,the rice seeds have a low degree of dispersion and are easy to form a small area of blocky "boiling",which leads to a decrease in the qualification rate of seed suction during work;at the same time,the high-frequency vibration causes the overall vibration of the device body,it is easy to cause the seeds to fall off during the seeding process of the sucker tray,reduce the seeding qualification rate and the working life of the device.In order to solve these problems,in this paper,an innovative method is proposed which uses a force of air blowing and vibration together to make the seed population be “boiling”,and a pneumatic-vibrating supply seed tray structure is improved and designed to reduce the frequency and amplitude of the supply seed tray.The main research contents of this paper are as follows:(1)The structural design of the Air-blowing and vibrating supply seed tray.This research analyzes the composition structure and working principle of the vacuumvibration tray precision seeder,especially the working principle and "boiling" mechanism of the supply seed tray excitation structure;through the analysis of the problems existing in the supply seed tray,the idea of "boiling" the seed population by the air blowing force and the vibration excitation force innovation is put forward,the air force-vibration type seed tray structure is designed.(2)Flow field analysis of Air-blowing and vibrating supply seed tray.Through the theoretical research of computational fluid dynamics,a suitable flow field model is determined;the flow field model of the pneumatic-vibrating seed tray gas chamber is established by the three-dimensional software UG,and the flow field model which meets the flow field characteristics and high-speed calculations tetrahedral mesh is divided by the ICEM-CFD software;with the aid of fluid simulation software FLUENT,the flow field is simulated and analyzed under different inlet pressure values,the number of air inlets and the aperture of the air chamber;and the structure of the seed tray is optimized through orthogonal simulation experiments to determine the air chamber pores are at the average maximum flow velocity when the air pressure value is 22 KPa,the number of air inlets is 2 unit and the pore diameter is 2mm.(3)The analysis of the movement process of the rice seed in the Air-blowing and vibrating supply seed tray by EDEM-FLUENT coupled simulation.Through the analysis of the movement state of rice seeds and the study of the theoretical basis of discrete element,the super rice particle model is established by API replacement method.The obtained particle model is composed of 174 small spherical particles with a diameter of 0.6mm connected by Bond keys.Through FLUENT-EDEM coupling simulation simulates the movement state of the rice seed when the two phases are coupled,the particles are labeled and analyzed to obtain the time-displacement diagram of the particles,and it shows that the motion state of the particles is sinusoidal,which is consistent with the actual motion state.(4)The bench test of Air-blowing and vibrating supply seed tray.Process and install the pneumatic-vibrating supply seed tray structure,and use the pass rate,replay rate and missing rate as the seeding performance evaluation indicators to test verification on the pneumatic-vibration type seed plate test platform;firstly,the airfilled and non-aired the comparative test verifies that the pneumatic-vibration seed tray can reduce the vibration frequency by 1.5 Hz and the amplitude by 0.25 mm while achieving a higher seeding qualification rate,reducing the overall vibration of the machine and increasing the seeding qualification rate;secondly,the orthogonal test of sub-rotation combination determines the mathematical regression model between the seeding performance index and inlet air pressure,vibration frequency and amplitude,analyzes the influence effect relationship.With the help of the data processing software Design Expert V8.0.6.1,the optimal working parameters are obtained when the inlet pressure value is 19.49 KPa,the vibration frequency is 9.00 Hz,and the amplitude is2.65 mm,the effect is the best.At this time,the seeding test index pass rate,rebroadcast rate,and cavitation rate prediction values can reach 94.22%,3.27 %,2.87%;Finally,a field test is performed to verify the predicted value,and the test result is basically consistent with the predicted value.