Design And Experiment Of Pneumatic Cylinder Array Precision Seed-metering Device For Cotton

Xinjiang is the largest production base of high quality cotton and commodity cotton in China.Sowing is one of the most important links which affect the development of cotton industry.Precision sowing not only save a lot of seeds,reduce staff labor intensity,but also increase production and stable yield,with significant economic and social benefits.In order to solve the problem of seed-metering device for cotton such as complex structure of gas transmission pipeline,the large energy consumption and seeding monomer can only achieve single row sowing.Based on the comprehensive analysis of the research of pneumatic precision seed metering device at home and abroad,a pneumatic cylinder array precision metering device for cotton was designed,based on the agronomic requirement,which combined the features of array suction and airflow clearing with side direction.This paper explored and studied the pneumatic cylinder array precision seed-metering device for cotton by combining theoretical analysis,computer simulation and experimental research.The working principle and component of precision seeder were introduced.Through the theoretical analysis of seed filling,seed clearing,seed carrying and seed dropping,the kinematics and dynamics models of the seed metering process were established and the key factors that affect the process of seed metering were studied.Based on the theory of computational fluid dynamics,the Fluent software was used to simulate the airflow field in the negative pressure chamber of the metering device,and the relationship between the uniformity of the flow field and the diameter of the hollow shaft and the distribution law of the through-hole were revealed.Finally,the performance test of pneumatic cylinder array precision seed-metering device for cotton was carried out,and the influence of various experimental factors on the performance of seed metering was studied and the optimal combination operational parameters were determined.The main contents include:(1)According to the agronomic requirement and physical and mechanical properties of cotton seeds,a pneumatic cylinder array precision metering device for cotton was designed,which combined the features of array suction and airflow clearing with side direction.The paper analyzed and determined the structural parameters of the key part of seed-metering device.(2)According to the working process of the pneumatic cylinder array precision seed-metering device for cotton,based on engineering mechanics and fluid mechanics theory,through the theoretical analysis of seed filling,seed clearing,seed carrying and seed dropping,the kinematics and dynamics models of the seed metering process were established and the key factors that affect the process of seed metering were studied.(3)Through theoretical analysis of air flow field seed-metering device vacuum cavity,to identify the fluid state,a drum vacuum cavity flow system model,using Fluent software in the standard k-? turbulence model and standard wall function method,the simulation analysis of hollow shaft flow air flow distribution,different axial suction hole flow field,hollow section shaft through hole diameter,hole distribution of flow field uniformity effect,and the relationship between the uniformity of the flow field and the diameter of the hollow shaft and the distribution law of the through-hole is revealed.The velocity variation coefficient of the suction hole at the center of the negative pressure chamber is less than 5%,that is,the velocity field distribution at different suction holes is basically uniform,which indicates that the hollow shaft structure and parameters are reasonably designed.(4)The bench test was executed by JPS-12-type seeding performance test bench,cotton seed Xinluzao 48 was selected as experimental material in test.Based on pre-experiments,the cylinder speed,hole diameter and vacuum pressure were taken as main impact factors,the quality of feed index,miss index and multiple index were taken as response indices,and the second orthogonal rotation combination test was executed,which used the Design-Expert software.The regression models were established,and effects of various factors on the performance indices were analyzed.The research gained the best combination of the parameters by using multi-objective optimization,as follows: the cylinder speed was 15.5 r/min,the hole diameter was 3.5 mm,and vacuum pressure was 4.2 kPa.Under the condition of the optimal combination parameters,the quality of feed index,miss index and multiple index were 93.5%,2.0% and 4.5% respectively.According to optimization parameter combination,the verification test was repeated 5 times,the results showed that the experimental results were basically consistent with the optimization results,and the sowing quality satisfies the requirements of precision sowing for cotton.The sowing adaptability experiment was carried out under the same conditions with three cotton seeds(Xinluzao 48,Xinluzao 52 and Xinluzao 60),whose overall dimension exist some differences from each other.All the quality of feed index were more than 92%,all the miss index were less than 3%,all the multiple index were less than 5%,indicating that when planting different cotton seeds,the precision seeder had a certain adaptability to different varieties of cotton seeds.The study provides a theoretical reference for the design of pneumatic cylinder precision seed-metering device for cotton.