Design And Test Of Duckbill Seed-metering Device For Rice Film Spreading And Hole Sowing Machine

This thesis addresses the lack of seeders suitable for rice mulch hole sowing,and the traditional duckbill seeder has high vibration during the opening and closing of the duckbill and poor stability of the hole sowing volume.The thesis designs a duck-bill seed-metering device for the rice film cavity seeder,defines the structure and working parameters of the key components of the duck-bill seed-metering device,analyzes the population movement law of the duck-bill seed-metering device using EDEM software simulation,optimizes the cam mechanism of the duck-bill seed-metering device using multi-body dynamics simulation method and DEM-ADAMS coupling simulation method,and conducts bench seeding performance tests of the duck-bill seed-metering device and field seeding performance tests successively.The suitable structure and working parameters of the key components of the seed-metering device were clarified by conducting bench seeding performance tests and field seeding performance tests.This study provides a theoretical basis for the design and optimization of the paddy film seeder.The main research contents are as follows:(1)Based on the requirement of broken film hole sowing for rice mulching and the planting agronomy of 5-10 seeds per hole for conventional rice precision hole sowing,a duckbill sowing device with double side seed filling was designed,the working principle of the duckbill sowing device was elaborated,the mechanical model of rice seed in the sowing drum was constructed,the critical speed of the sowing drum was clarified to be 0.8m/s,and the suitable inlet width size of the seed pickup block and the deflection angle of the type hole were theoretically analyzed.Theoretically analyzed the appropriate seed inlet width and hole deflection angle of the seed picker.(2)The curvilinear acceleration profile of the cam mechanism of the duckbill seed-metering device was designed,the parametric equations of the cam profile were constructed,and the influence of the initial position angle and length of the pendulum on the thrust pressure angle of the cam mechanism was analyzed theoretically with the help of Matlab software;the main structural parameters of the cam mechanism were optimized by ADAMS with the contact force between the roller of the pendulum follower and the cam profile as the evaluation index,and the length of the pendulum was 77.1 mm,the radius of the corresponding cam base circle was 132.8 mm,The pendulum initial position angle is 9°,and the radius of the corresponding cam base circle is 132.8 mm.(3)The frictional contact parameters between the rice seed particles were calibrated by the direct seeding method,and the suitable static friction coefficient between the rice seed particles was 0.413 and rolling friction coefficient was 0.033.The discrete element simulation analysis of the seeding process of the duckbill seeding device was carried out to clarify the movement law of the seed population,and the width size of the seed pickup block inlet and the deflection angle of the type hole were initially determined to be in the ranges of 7.8～8.4 mm and 1.71～2.41°,respectively.The coupled DEM-ADAMS model of the duckbill inlet opening seeding process was established,and the rationality of the design of the main structural parameters of the cam mechanism was verified.(4)By using the central combination test method,the suitable seed inlet width size and type hole deflection angle of the seed pickup block were defined as 8.1 mm and 1.99°,respectively.At this time,the results of the bench seeding test of the duckbill seeding device were 4% leakage rate,84.8% pass rate and 11.2% reseeding rate.The field sowing performance of the duckbill seeding device was 85.8% pass rate,4.03% miss seeding rate,10.17% reseeding rate,36.4 mm average film hole length,8.25% coefficient of variation of film hole length,130.16 mm average film hole distance,90% pass rate of hole distance,7.22% coefficient of variation of hole distance,2% hole hole misalignment rate,the above data meet the agronomic requirements of rice mulching.The above data meet the agronomic requirements of rice mulching.