Optimal Design And Simulation Of Greenhouse Vegetable Precision Seeder

With the continuous improvement of China's agricultural production level,the planting scale and planting requirements for vegetables have also begun to implement standardization With the continuous advancement of urbanization and the continuous improvement of people's living standards,people's demand for high quality vegetables has become increasingly high.Provinces are also gradually promoting large-scale,standardized vegetable planting.Using automatic seeding equipment instead of manual planting can greatly liberate labor force,reduce cost and improve the production efficiency of greenhouses.In addition to the transplanting mode,precision seeding is another kind of vegetable planting mode,the price of the vegetable precision planter produced in China is low and most of them are transmitted by chain gear whose sowing precision is not high enough to meet high standards.however,the imported vegetable precision planter is expensive,thus,it is not suitable for large-scale promotion in China,therefore,there is still much room for development of mechanical equipment suitable for vegetable sowing in domestic greenhouse.Based on the above reasons,an air-suction greenhouse vegetable precision planter was designed,which is characterized by good stability,reliability,universality and low cost.In the design process of this paper,a large number of investigations and studies were carried out,and relevant documents were consulted for analysis in combination with the actual production.CAD three-dimensional software was used to design,combining with several CAE analysis softwares to analyze and study the planter.Firstly,the flow field performance of the gas delivery pipe of the air-suction greenhouse vegetable precision planter was analyzed by FLUENT software,and the related factors between the diameter and the hole distance of the seed-sowing device and the internal flow field were specifically analyzed.After optimizing the diameter of the shaft hole,the structural parameters of the outer tube of the seed-sowing device were analyzed and calculated.The velocity cloud diagram analysis results show that the air flow inside the seed-sowing device with a hole distance of 200 mm has basically the same trajectory,which is a relatively ideal distribution of the air flow field inside the seed sowing device.Secondly,through the combination of the airflow negative pressure distribution inside the seed-sowing device and the adjustable absolute pressure separator,it is set that there are 5 rows of air holes and 6 rows of seed suction holes on the gas conveying pipe of the seed-sowing device.Through the analysis and calculation of the mechanics and motion of the seed-sowing device,it is concluded that the factors influencing the qualified index of the seed-sowing device are the negative pressure of the seed suction hole,the advance speed of the seeder and the seed suction angle of the seed-sowing device.The DEM-CFD coupling method was used to establish the discrete element model of seed and the working boundary of seed-sowing device.The FLUENT-EDEM simulation software was used to simulate the seed sowing experiment,and the simulation data of seed-sowing qualification index,missed seeding index and reseeding index were recorded and used as analysis indexes.The data was imported into the Design-Expert software,the three-factor three-level quadratic orthogonal rotation combination experiment method was selected to process the simulation data,and the seed qualification index,missed seeding index and reseeding index were used as the evaluation indexes,and then obtained the optimal parameter range for the effect on the performance of the seed-sowing device.When the seed absorption angle was set as 30°,the negative pressure value inside the seed-sowing device was 675 Pa,and the seeder's forward speed was 0.5m/s,the best data results were 92.9%,4.3% and 2.7% respectively.Thirdly,in order to further improve the performance of the seeder,combined with the structural characteristics and functions of the seed-furrow opener,the structural performance of the seeder-furrow opener was simulated and analyzed.The model structure was imported into the EDEM software environment for analysis.Data results were obtained by using the simulation software.Through the coupling analysis of EDEM and ANSYS,it is found that the maximum stress of the seed-furrow opener in the soil is 2.74 MPa,while the maximum force that the front edge of the seed-furrow opener can bear is 30.3MPa,which meets the actual working requirements of the seed-furrow opener.It provides certain research basis and reference data for studying the structural characteristics and applicable performance of the seed-furrow opener.Finally,in order to better complete the design of the whole machine,this paper combined the structural characteristics of the traditional grain planter to optimize the design and analyse the structure of the transmission system,power system,frame,walking mechanism and the whole machine structure of the vegetable planter,and finally determined the design scheme of the whole machine of the vegetable planter.The conclusions obtained in the simulation experiment can provide theoretical basis and parameter basis for the further research of air-suction precise vegetable seeder.