Design And Research Of Buckwheat Seed Metering Device Based On Discrete Element Method

Buckwheat is widely distributed in the world and has a large area of planting.The two most important cultivated varieties are common buckwheat and tartary buckwheat.More than1 million 300 thousand Hectare of buckwheat is planted in China for a year.The buckwheat is mainly distributed in the north of China;Tartary buckwheat is mainly concentrated in Sichuan,Chongqing Wuling,Yunnan Guizhou Plateau and other areas,and the cultivation of Tartary Buckwheat in Wuling area of Chongqing is mainly concentrated in Youyang county.Youyang gives the first place to tartary buckwheat and also plant some common buckwheat,the total planting area reached 180 thousand acres.In this area,the degree of sowing mechanization is low,and the labor cost accounts for 80% of the total cost of buckwheat planting.The problem of buckwheat sowing in this area has become the biggest obstacle to the development of buckwheat industry.This paper designed a universal seeder for common buckwheat and tartary buckwheat based on the actual demand of Youyang county and the science and technology innovation of the social and people's livelihood guarantee in Chongqing.To design a universal buckwheat seeder,the key challenge is to design a universaal seed metering device for common buckwheat and tartary buckwheat.For this purpose,this paper has carried out the following main research and got the following conclusions:(1).Literature reading and information inquiry.By reading a large number of documents and referring to relevant information,It is found that the degree of mechanization of the sowing of buckwheat at home and abroad is not only very low,but also useing other grain seeder to sow buckwheat.Because of its poor adaptability,the quality of sowing is low.Through comparative analysis,this paper choosed the external grooved wheel seed metering device as the research object,and adopts the discrete element simulation method to guide the development of buckwheat seed metering device.(2).Measurement of physical and mechanical properties of buckwheat seeds.Selected Youyang common buckwheat No.1,and No.2 and tartary buckwheat as the research object.Measured the basic parameters of buckwheat,such as seed density,three-dimensional size,dynamic friction coefficient,static friction coefficient,elastic modulus,stiffness coefficient,shear modulus and impact recovery coefficient,ect.(3).Simulation and result analysis on the working process of buckwheat seed metering device.According to the design experience of the manual of agricultural machinery design,4kinds of external grooves were designed and a simulation model was established.In the process of simulation,orthogonal test and supplementary verification test were used to study the relationship between the displacement of 4 kinds of seed metering devices and the rotation speed of the grooves,the radius of the grooves and the number of grooves.Then eliminated 3kinds of groove wheel model according to the demand of sowing quantity,and the mainparameters of the slot wheel were determined: the diameter of the groove wheel was determined to be 60 mm,the maximum working length was determined to be 30 mm,the radius of the groove was determined to be 3mm,and the number of the grooves was determined to be 20.A single factor experiment with variable speed of grooved wheel was carried out subsequently,to study the relationship between the rotational speed and displacement of the grooved wheel and the condition of seed filling.According to the simulation results,the suitable working speed of the grooved wheel was selected to be58.58r/min.(4).Bench test and result analysis of buckwheat seed metering device.According to the simulation results,the corresponding external grooves were processed,and the relationship between the speed of the grooves and the displacement was studied by using the self-made performance test bench of the seed metering device.The results of the test are analyzed,and the optimum working speed of the slot wheel is optimized according to the simulation results,and it is determined to be 55.07r/min.The relative error of the displacement is 2.93% ~9.90%,compared with the influence of the rotating speed of the slot wheel on the displacement of the seed metering device in the comparison simulation test and the bench test.At the same time,the relationship between the rotational speed of the grooved wheel and seed filling was studied by using high-speed photography.Compared with the simulation test,the relative error of the number of seeds discharged from the single round circle of the grooved wheel is2.31% ~7.69%.(5).Machine design and field test.The machine was designed and manufactureed to carry out a field test.The test results showed that the rate of overlying soil,the qualified rate of the thickness of overlying soil,the qualified rate of sowing depth,the coefficient of variation of the consistency of the row displacement and the coefficient of variation of the stability of the total displacement all reached the expected value.