Design And Experiment Of Suction Seed Metering Device For Rice Hill-direct-seeding

Rice plays an important role in the world’s food crops.Rice is also one of the main food crops in China,and its yield and quality directly affect the national food production security and strategic development.The single cropping rice in cold areas of North China is one of the main producing areas of green and high-quality rice in China,and its mechanization directly marks the development of green and high-quality rice.The research of rice mechanization planting is also an important content to improve the level of rice mechanization.Rice mechanized direct seeding is a kind of mechanized planting,which has the advantages of simplifying operation procedure,saving labor and cost,and increasing economic benefits.Mechanized precision hole direct seeding of rice mainly uses seeder to sow rice seeds into the field according to the specified number of grains,grain spacing and sowing depth.Among them,the rice precision metering device is the key part of the rice mechanized sowing process.The existing rice metering device mainly aims at hybrid rice sowing,which is not suitable for the conventional direct seeding of rice in Northeast China,and has the problems of unstable sowing amount and easy to damage rice seeds.Therefore,it is urgent to develop the seeding device suitable for mechanized direct seeding of conventional rice in cold areas of North China.In view of the above background and problems,this study carried out the design and research of suction seed metering device for rice hill-direct-seeding by consulting the research status of air suction precision seeder.To provide theoretical basis for the research of conventional rice precision rice seeder in northern China reference resources,this study combined with theoretical analysis,virtual simulation and bench test.The main contents are as follows:(1)Physical characteristics determination and principal components analysis of typical single cropping rice in cold areas of north ChinaTwelve typical rice varieties suitable for planting in Northeast China were selected as experimental materials.A variety of agricultural material test bench have been built to measure the rice seed physical parameters.By using the principal component analysis and cluster comprehensive analysis,the index of characteristic parameters was simplified,the comprehensive score of samples was judged,the aggregation and classification research was carried out,and the scientific and reasonable evaluation system was constructed.The study can provide reference for the structure design,virtual simulation and bench test.(2)Mechanism analysis and optimization design of suction seed metering device for rice hilldirect-seedingA kind of suction seed metering device was optimized and designed by adopting various working modes,such as auxiliary seed stirring and filling,flexible seed cleaning,variable seeding and precision seeding.The structure and parameters of the key components of the seed metering device,such as the seed metering plate,the seed stirring device and the seeding rate adjusting device,were optimized to improve the performance of the seed metering device.(3)Numerical simulation and analysis of performance of suction seed metering device for rice hill-direct-seeding based on CFD-DEMThe seed discrete element model and virtual simulation model of seed metering device were also established.The influence of suction hole shape on seed suction performance was analyzed.The single factor experiment of virtual simulation was carried out.Objective to explore the effect of the arrangement mode of seed metering plate holes on the uniformity of seed metering.On this basis,the structure was improved and optimized,and the chamfered suction hole and triangular arrangement hole were selected as the optimal structure.(4)Research on bench performance test of suction seed metering device for rice hill-directseedingSingle factor,multi factor and verification bench tests were carried out by selecting working speed,working pressure and stirring brush length as test factors,and qualified index,replay index and missed index as evaluation indexes.The tests results show that the working speed,working pressure and the length of seed stirring brush were the important factors affecting the seed metering performance,and there was interaction among these factors.The overall performance of the metering device decreases with the increase of the working speed.When the working speed,working pressure and stirring brush length were 20.70 r/min,-4.0 k Pa and 10.50 mm,respectively,the seed metering performance of the seed metering device was the best.The qualified index,replay index and missing index were 91.26%,4.50%,and 4.24%,respectively,which could meet the requirements of rice precision hill direct seeding.