| China is a big country in vegetable production and consumption.Its production and consumption level ranks first in the world,and pepper is one of the most widely grown vegetable types in China.In recent years,the potential of peppers as a cash crop has been continuously tapped,and the annual output value of peppers ranks first in all types of vegetables.With the popularization and cultivation of pepper as a cash crop and the improvement of modern agricultural plant protection in China,the traditional transplanting method has low working efficiency and is no longer suitable for large-scale cultivation of pepper.It is urgent to develop a pepper precision seeder.However,because of the special shape of pepper seeds,ordinary precision seed metering devices are difficult to apply to the precision seeding of peppers,and have become an important factor restricting the development of pepper industry in China.Aiming at the above problems,this paper proposes a theory and a precision seeder structure suitable for the precision seeding of peppers.The purpose is to develop a pneumatic precision seeder that can meet the precise seeding of different seeds such as peppers.Process to improve the comprehensive benefits of pepper planting.The main research contents of this article are as follows:(1)In order to make the designed seed metering device fully suitable for the seeding operation of peppers,test and analysis on the material characteristics of 6 types of pepper seeds(including Erjintiao,Chaotian pepper,Yiduhong,line pepper,scallion pepper and millet pepper).The main physical parameters such as their 1000-grain weight,triaxial size,water content,angle of repose,and sliding friction were analyzed experimentally,and a three-dimensional CAD model and a discrete element model of pepper particles were established.(2)Based on the analysis of the characteristics of pepper seed material and the mechanism of the seeder,design a seeder that can complete the seeding work of pepper with high quality,and determine the seeder to control the seed supply amount and air blowing through the screw seeding mechanism.The structure of the seed feeding mechanism for seed fluidization and seeding with the air suction drum mechanism.The kinematics model analysis of the working process of the seed metering system is carried out,and the mathematical models of the spiral seed feeding,air blowing seed feeding,roller seeding and seeding process are established,and the main factors affecting the working process of the seed metering are determined.(3)Establish a simulation model of the airflow field and particle field of the seed meter,and calibrate the attributes of the discrete element model of pepper particles.Based on the CFD theory,the optimal shape of the suction hole was determined,and the air blowing and air suction flow fields were analyzed.The DEM theory was used to analyze the movement of the pepper particles during the seeding and seeding process;based on the CFD-DEM coupling theory The suspension characteristics of the pepper population were studied to determine the optimal airblowing seeding speed,and the dispersion and uniformity of the pepper population in the airblowing seeding process.Simulation analysis was used to verify and determine the rationality of the seed metering system structure.(4)The trial production of the seeder system was carried out,and the leakage index,replay index and pass index were determined as the performance test indicators of the seeder.The seeder was tested,and the optimal optimization parameters of the seeder system were obtained through regression analysis: forward speed 7.72km/h(the corresponding speed is set to 28.56r/min),and the negative pressure value was 4.40 kPa.The eligibility index was 91.32%,the replay index was 4.51%,and the missed broadcast index was 4.17%,and the test results of this bench were basically consistent with the theoretical analysis results. |
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