Precision seeder design and experimental study of friction
|School||Shenyang Agricultural University|
|Course||Agricultural Mechanization Engineering|
|Keywords||metering device mechanical precision soybean dropping frequency experimentalresearch high-speed image|
Planting is an important part of agricultural production process, according to agricultural technologyrequired to planting on time, adequate seeds, environmental conditions, to ensure crop growth anddevelopment. In order to ensure operational efficiency, reduce fuel consumption, supporting the rationalityof the timeliness and the large area planting requirements, the operating speed and seed frequency of seederreached higher requirements. To this end, the mechanical precision metering device has been researched. Tomeet the precision seeding performance, seed-filling acting and dropping frequency were improved. Thehigh-speed precision planting of small size crop or soybeans was expected.Research of physical properties of soybean seeds provides basic parameter and design basis of seedmetering device. Through experimental testing it is obtained the long-axis diameter of, short axis diameter,middle diameter, and single seed mass of soybean seed. According to the basic data it is obtained ofsoybean seed arithmetic even diameter, geometric even diameter, single seed volume, spherical rate,density and other physical parameters. Using the tilt test, static friction coefficient of soybean and such asPVC plate cold-roll steel sheets, galvanized steel sheet, polymethyl methacrylate are tested. Using directshear test method, soybean seed internal friction angle is tested. Using injection method, angle of repose ofsoybean seed is tested. Base on the whole soybean compressive test, it is obtained the soybean seedscompression properties, nominal compressive limit, and elastic modulus.The friction principle of seed was put forward, according to the friction principle a new typeseed-metering device was designed. Through friction seed-metering device of cell wheel feed type andvertical disc type was tested, the performance experiment demonstrated that the seeds were driven to flowby the friction on the friction part and model-hole and the filling power increased as well as the efficiencywas improved. The vertical plate precision seed-metering device is fined than cell wheel feed precisionseed-metering device on the seed entering space and seed-dropping device. A new type seed-meteringdevice was design on arranged structure, shell, friction seed-plate, seed entering space, seed-droppingdevice etc.Based on the theoretical analysis of filling force, seeds cross section and longitudinal cross-sectionpressure was obtained in the seed entering space. A central composite relatable orthogonal experimentaldesign of response surface methodology was employed to develop the second order polynomial regressionmodels.Positive pressure of seed was obtained in the electric measurement. Using high-speed imagingtechnique founded: seed filling is direct slide type-hole, slow squeezing type-hole, and high speed slidinginto the type-hole. And seeding uniformity is affected by the type-hole and seed shape, size. Seed fillingspace within the outflow of seed particle number and seed number per turn were investigated on the seedplate rotate speed.Based on slide-out, roll out seed-clearing principles, a new type of seed-clearing structure wasdesigned. The mechanical analysis for commonly seed-clearing structure of rigid clear plate, elastic clearplate, rotate wheel. The seed-clearing type is that seed slid off the hole to clearing-seed, seeds remain in thetype-hole can not be clear, seeds self-locking movement clearing-seed. The kinematics analysis ofself-locking seeds was analyzed. The rotate seed-clearing mechanism has been discovered. A new type ofwire machinery clearing-seed structure was designed. The mechanical and kinematics of seeds wereanalyzed in wire-steel seed-clearing process. Wire clear mechanism was explored. The clearing-seed ofjoint gravity and mechanical is used in the friction vertical plate precision seed-metering device. Usinghigh-speed imaging technique to observe, clearing-seed was fine. In order to improve accuracy of throwing of friction vertical plate precision seed-metering device,reduce the seed slipping, bouncing on seed uniformity influences of dropping process. twice droppingdevice was designed based on direct seed-dropping device. The dropping mouth height was reduced. TheSeed relative seed-ditch horizontal velocity and the falling speed were reduced. The seed space wasimproved uniformity. The seed of seed-dropping process was analyzed by motion simulation andhigh-speed image analysis. Seed trajectory, velocity, acceleration, and seeds force were analyzed on variousfactors. The direct seed-dropping mouth position and width, seed-dropping tube length was analyzed onvarious seed plate rotate speed. Seeds were collision and bouncing in the rotate seed-dropping tube.A central composite relatable orthogonal experimental design of response surface methodology wasemployed to develop the second order polynomial regression models. An optimum combination ofseed-metering device parameters was obtained. Friction vertical plate precision seed-metering device issimple structure, reliable performance, high quality, and high speed for precision seeding soybean crops.