| Potato is China's fourth-largest food crop,and it has important strategic significance for safeguarding national food production security and realizing farmers'income increase and agricultural efficiency.Potato precision seeding technology is an advanced technology that uses seeding machines to accurately and quantitatively seed seed potatoes to predetermined positions in the soil according to agronomic planting requirements.The performance of the precision seeder directly affects the quality and efficiency of its seeding operations,and is of great significance to the promotion of potato precision seeding technology and the improvement of the mechanized potato planting level.Aiming at the problems of poor seeding quality,poor performance stability,small suitable sowing range,and difficulty in adapting to high-speed operation,the commonly used potato mechanical seeders currently used in this study.Agronomic requirements for potato seeding,starting from breaking through the key core problems of potato precision seeding machines and tools,combining theoretical analysis,virtual simulation,bench performance testing and integrated machine trial production,etc.to carry out pneumatic potato precision seeding The research on the operation mechanism and parameter optimization of key devices aims to provide theoretical support and technical reference for the innovative research and development of potato planters and their key components.The main contents are as follows:(1)Determination of material characteristics of typical potato seed potatoes in the first cropping area in the north:The typical potato seed potatoes planted in the first cropping area in the north were selected as the research object,and the geometric dimensions,water content,mass,density,bulk density,static friction angle and static friction angle of the potato seed potatoes were determined.Basic material parameters such as angle of repose.The average density of whole potatoes is 1.12×10~3 kg/·m~3,the average bulk density is 0.532×10~3 kg/m~3;the average moisture content of potato seed potatoes is 75.4%,the average static friction angle is32.4°,the average sliding friction angle is 30.8°,and the rest The angle is between 29°and 32°;it provides basic data and reliable reference for the optimization design and virtual simulation of the structural parameters of the key components of the subsequent planter.(2)Analysis of the operation mechanism of negative pressure seeding and positive pressure seeding of the potato rower:A new method of potato precision seeding based on negative pressure seeding and positive pressure zero speed seeding is proposed,which reveals the stability of the potato planter's potato removal mechanism The pneumatic charging mechanism was analyzed,and the operation principle of negative pressure seeding and positive pressure seeding of multi-arm uniformly distributed potato discharge was analyzed;an air chamber structure,whole potato and cutting with a split cone surface closely matched with no liquid lubrication were developed A new type of potato removal device for the general parts of potato tubers,which is uniformly distributed on the circumference of the air chamber at an angle of 18°between the spoon and the tube between the spoon rooms;the negative pressure seeding parameters suitable for mechanized seeding are determined.For conventional potatoes,The specification range of seed potatoes is 30?60g/piece,the height of the seed surface is 150 mm,and when the negative pressure of the potato rower is-10 k Pa,the seed spoon can absorb the seed potatoes in the seed area;When the negative pressure of the potato rower is-3 k Pa,the planting performance of the test bench is good,and the reasonable seeding angle range is 44°?75°,which effectively improves the quality and suitable sowing range of the planter.(3)Simulation and analysis of the flow field of the pneumatic potato precision seeder fan:improved high-speed centrifugal fan dedicated to potato seeding,proved the optimal critical conditions for potato pneumatic seeding,determined the outer diameter of the blade to be 750 mm,and the installation angles for both import and export In the form of 90°,the working efficiency and effective pressure range of the fan are increased;a dynamic model of the fan's airflow field is established,and a virtual simulation study is carried out in conjunction with the fluid mechanics software Fluent.Finally,the main factors affecting the pressure performance of the fan are the top of the volute tongue and the outside of the impeller The clearance of the circumference,the radius of the arc of the top of the volute and the speed of rotation;when the radius of the volute is 28 mm,the gap between the top of the volute and the outer circumference of the impeller is 80 mm,and the speed is 2500 r/min,the fan pressure is-10.6 k Pa,which satisfies Operation requirements of pneumatic potato precision seeder.(4)Integrated design and performance test research of pneumatic potato precision seeder:combining agricultural machinery and agronomy,for the key issues of potato mechanized cultivation in the first cropping area in the north,a rack assembly,transmission system,fertilization system,ditching system are configured,Seeding system,soil covering assembly,cracking assembly and other key components,integrated design of pneumatic potato precision seeding machine that can complete multiple operations such as trenching fertilization,precision seeding,soil covering cracking and so on.Three kinds of conventional potatoes and mini potatoes,Eugene,Zhongshu No.5,and Shapotti,were selected as the test materials.Field operations were conducted on the quality and performance of the planter.The test results showed that the pneumatic potato planter was sowing conventional seeds and potatoes.For mini-potatoes,the maximum operating speed reaches 10.1km/h,the missed sowing rate is 1.86%and 1.40%,the reseeding rate is 1.56%and 1.78%,and the coefficient of variation of plant spacing is 3.6%and 2.8%,which satisfies the potato sowing operation requirements. |
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