Design And Test Of Swinging Plate Seed-metering Device For Soybean Plot Breeding Based On Discrete Element Method

Based on a comprehensive community of plot breeding seeders and their corresponding seed-metering device at home and abroad,this paper aimed at the characteristics of plot breeding,combined with the planting mode of soybean field experiments and agronomic requirements,aimed at the poor adaptability of soybean plot breeding and for the problem of seed residues in the seed box,the theoretical analysis,simulation analysis,experimental research,bench test and field test were used to carry out the research on the key technologies of the swinging plate seed-metering device for plot breeding,and complete the work content as follows.(1)Integrated design of the swinging plate seed-metering device for plot breeding.With the guidance of agronomic requirements of plot breeding experiment,the swinging plate seed-metering device for plot breeding was designed.By the crank rocker,the device is drived and the seed disk can swing,which can realize the process of filling seed,clearing seed and arranging seed.It solves the problem of variety adaptability by means of detachable holes.The seed clearing function can be realized by setting the seed clearing plate at the bottom of the seed box(2)Analysis of size characteristics of soybean seeds and simulation test of type-hole filling.1)Firstly measure the three dimensions of the length,width and thickness of the seeds of seven varieties of soybeans,and calculate the sphericity and the coefficient of variation of mean diameter of the seeds.2)Select Dongnong 52,Heihe 44 and Qingren black beans as sphericity successively decreasing(average diameter variation coefficient increasing sequentially)as seed models,and use EDEM to perform discrete element simulation.The results show that,as the sphericity increases,the single-seed rate gradually increases,the multi-seed rate gradually decreases,and the empty-seed rate increases first and then decreases.3)In order to investigate the influence of sphericity and the variation coefficient of mean diameter on seed filling performance,a two-factor five-level quadratic regression orthogonal experiment was designed to analyze the seed filling performance of the seed-metering device based on discrete element simulation.The results show that,when the sphericity increases,the single-seed rate increases and the empty-seed rate decreases;when the variation coefficient of mean diameter increases,the multi-seed rate increases.4)In order to verify the accuracy of the simulation test,Hefeng 53 and Suinong 26 were selected and tested on the JPS-12 seed-metering performance test bench.The results show that,the test verification values and dispersion of Hefeng 53 and Suinong 26 The relative error value of the theoretical output of the meta-simulation regression equation is small and has the same factor index response trend.(3)Simulation and experiment on the parameters of seed plate type-hole in plot breeding.1)Theoretical analysis is used to analyze the characteristics of the type-hole.According to the probability occupied by the three position of the seed horizontally entering the hole,vertically entering the hole,and rolling into the hole.The diameter ratio and the chamfering ratio of the hole are calculated.The results show that the range of the hole diameter ratio is 1.60～2.10,and the range of the chamfering ratio of the hole is 0～0.3.2)According to the determined type-hole diameter,the ratio of the chamfered length of the hole and the soybean seed warp,a three-dimensional model of the internal precision seed-metering device was established.The EDEM software was used to simulate the seeding situation of the seeding plate with different type-hole sizes to sow the seeds.The ratio of the type-hole diameter of the plate and the chamfer ratio of the hole are used as test factors.The single-seed rate,multi-seed rate,and empty-seed rate are used as test indicators.A two-factor and five-level quadratic regression orthogonal rotation combination test is designed.The results show that:When the hole diameter ratio is 1.73～1.91 and the hole chamfering ratio is 0.04～0.25,the single-seed rate is greater than 70%,the multi-seed rate is less than 20%,and the empty-seed rate is less than 10%.3)In order to solve the problem of the adaptability of the seed-metering device to soybean seed varieties,a seeding plate with a removable type-hole was designed,and the four hole diameters and chamfer lengths were worthy of optimization.(4)Design and test of the swinging plate seed-metering device.1)This paper makes a theoretical analysis of the two kinds of seed-metering devices with or without the characteristics of quick return,and uses the slow travel of seed-metering device for seed filling and fast travel for seed-metering device,which not only guarantees the quality of seed-metering device for seed filling,but also improves the efficiency of seed-meteringdevice.At the same time,ADAMS simulation is used to simulate both symmetric and asymmetric swing angle,and the results show that;appropriately increase the swing angle of the seed filling area to make the seed filling area of the seed-metering device easier for seeds to enter into the hole.2)The quick return characteristic of the crank and rocker mechanism is used in the design of the seed-metering device,seeding is performed when the swing speed is fast,and seeding is performed when the swing speed is slow,which not only ensures the stability of seeding work but also improves seed operating efficiency.The experiments were carried out using discrete element simulation,and the prototype was processed for the bench test.The test results are consistent with the simulation results.(5)Simulation analysis and field test of the rapid return characteristic of seed plate.1)By means of ADAMS simulation,the swinging angle of the seed plate is simulated in two cases:symmetric and asymmetric.By analyzing the movement track and stress of seeds,the conclusion is obtained that the swing angle of the filling area should be increased appropriately to make the filling area of the plate bigger and the seeds enter the hole more easily.2)The field test of the prototype was carried out.The test results show that the data of the field test of the prototype meets the standards of superior products in "Product Quality Classification of Precision Cultivation Planters for Crops".