Study On Key Technology And Equipment Of Combined Air Suction Cotton Seeder

In order to further improve the mechanization level of cotton breeding and seeding,combined with the agronomic requirements of cotton community planting and the material characteristics of cotton seeds,a combined air-suction cotton community planter with precise seeding and rapid and thorough seeding was designed.Based on the testing of agricultural material characteristics of five different varieties of cotton seeds,the theoretical analysis of the force,velocity,and acceleration of cotton seeds on the air suction cup was carried out,and the structure of the combined air suction seed metering device was calculated.Parameters and motion parameters.On this basis,the seed cleaning system and control system are designed,and the whole machine of the combined air-suction cotton planter is designed.During the design process,FLUENT software was used to simulate the combined air-suction seed metering device,which provided strong support for the determination of structural parameters and motion parameters.In order to verify the correctness of the design,a seeding performance test was conducted on the seeding performance test rig.At the same time,the high-speed camera system was used to study the effect of the cotton seed adsorption posture on the seed filling performance,and the optimization of structural parameters and working parameters was obtained Combination,under this combination condition,the multiple-seeding rate and missed broadcast rate are the lowest.Field trials were conducted using trial-produced combined air-suction cotton plot planters.The coefficient of variation of plant spacing,multiple-seedingt rate,missed planting rate and seed cleaning performance were tested.The main research contents are as follows:1.Measurement of basic parameters and mechanical characteristics of cotton seedsThe moisture content,length,width,thickness,density,thousand-grain weight,angle of repose and friction angle were measured on 5 different cotton seeds.The average length of cotton seeds is about 9 mm-10 mm,the average width is about 5 mm,and the thickness is about 4.5 mm.The shape of cotton seeds is similar to the shape of a drop.The 1000-grain weight of cotton seeds is concentrated at 89.7 g-99 g;the density of cotton seeds is distributed around 0.89 g / cm~3;the average suspension speed of cotton seeds is 13.837 m / s,13.832 m /s,13.822 m / s,13.767 m / s,13.919 m / s;angle of repose is concentrated between 24.4 °-28.4 °.2.Overall design of combined air-suction cotton planterThrough the analysis of the agronomic requirements of cotton community planting,the overall structure of the combined air-suction cotton community planter is designed.The machine is mainly composed of a seeding system,a seed cleaning system and a control system.On this basis,through the theoretical analysis of the stress,velocity and acceleration of the seeding stage of the seeding device,the structure of the combined air suction seeding device was optimized;by the vacuum switching device of the seeder and the seed cleaning system The design realizes the rapid and thorough function of seed cleaning.Through the optimized design of the control system,continuous adjustment of plant spacing,line spacing and sowing depth is achieved;3.Use FLUENT to simulate the combined air suction seed metering deviceUsing simulation test technology,set different boundary conditions(including pressure and airflow speed)on the suction port section of the seed meter.First,the flow field(including speed field and pressure field)of the guide groove on the guide groove disk under open conditions)The analysis shows that under the open condition of the guide groove,the air velocity and pressure at different positions on the guide groove gradually decrease as the distance from the center of the guide groove plate increases.On this basis,under the same boundary conditions of the suction port section of the seed meter,the flow field of the air suction hole formed by the combination of the air suction disk and the guide groove disk was simulated and analyzed.The results show that: the pressure of the air flow at the inlet It is 300 Pa and the velocity is 21.97 m / s.At this time,the pressure of the airflow field of the air suction hole is 2481.8 Pa,and the velocity of the airflow is 61.67 m / s.The simulation results are basically consistent with the results measured by the experiment.4.Bench test of combined air suction seed metering deviceUsing the built seed meter performance test bench,with the help of Design expert software,a three-factor three-level orthogonal test was carried out,and the experimental parameters of the seed meter’s better working performance were determined through the test to provide parameter basis for the field seeding test.The best combination with the lowest leakage rate is wind pressure 2.67 k Pa,groove width 2.83 mm,seeding speed 20 r / min,and leakage rate 0.59%.Mathematical models of multiple-seeding rate and missed rate were established,and the best solution with lower multiple-seeding rate and meeting the requirements was wind pressure 2.35 k Pa,slot width 2.78 mm,seeding speed 20 r / min,and multiple-seeding rate 4.3%.5.Use high-speed camera system to study the effect of adsorption posture on seed performanceThrough the analysis,we know that there are three kinds of adsorption gestures on the arc section of the seed metering device: A cotton is similar to the bottom of the triangle;B cotton is similar to the waist of the triangle;C cotton is similar to the oval.The face is sucked into it.Through theoretical calculations,it is found that the suction required to maintain attitude three is the smallest.Under the same vacuum pressure,the seed is most stable when the attitude three is adsorbed,which is the ideal attitude for seeding.There is a phenomenon of posture A and C conversion to posture.Using TEMA software to track the movement of cotton seed,the speed and acceleration images of cotton seed are obtained.From the image analysis,it is known that the speed of posture A and C is unstable.Attitude B speed is relatively stable.This is of great significance for reducing the missed seeding rate and improving the seeding performance.6.Field test of combined air suction cotton planterField trials were conducted on the combined air-suction cotton planter with Shannongmian No.11 seed,and the mathematical models of multiple-seedingt rate and missed planting rate were established.After parameter optimization,the optimal parameter was determined to be 1.3-1.5 m./ s,wind pressure 2.5-2.8 k Pa,width of air suction cup groove 2.6-2.8 mm.And analyzed the influence law of planter advancement speed on the coefficient of variation of plant spacing.It is concluded that the coefficient of variation is smaller when the velocity is 1.2-1.5 m / s.At this time,the multiple-seedingt rate and missed rate of the combined air-suction cotton breeding planter are less than 3%,and the sum of the multiple-seeding rate and missed rate is less than 5%,which meets the planting requirements of cotton breeding communities.The performance test was carried out on the seed cleaning system.During the field test,different vacuum degrees of 2.2,2.6,and 3.2 k Pa were tested.Each group of vacuum degrees was subjected to 20 times of seed cleaning operations,and 100 seeds were added to the seed shell each time.Cotton species.The test results show that the residual rate is 0 every time.Seed cleaning rate reached 100%.Realized the timeliness and thoroughness of seed cleaning.The designed air-suction type cotton community planter’s seeding performance and cleaning performance meet the requirements of cotton community planting.