| Dry land rice direct seeding is a kind of cost-saving and water-saving planting pattern.But the emergence rate is low for the loose and shallow cover of soil,affecting seedling growth.Compaction is an effective way to firm the loose soil,increase soil moisture,and promote seed germination.A strip compaction mechanism was designed based on experimental study on effect of compaction pressure on rice growth and the analysis of characteristics of compactors of sowing machine.Experimental study on the compactors was carried out.The main contents and conclusions are as follows:(1)Experimental study on the effect of pressure on emergence and early rice growth was carried out and the results showed that compaction had significant effect on the indicators,and the optimum range of pressure is between 50 k Pa to 90 k Pa.(2)Strip compaction mechanism was designed based on the analysis of common compactors for seeding machines,the outer contour of the wheel was designed and optimized.Two pressure adjusting methods of spring adjusting and counterweight adjusting were designed.(3)Solid modeling and optimization of the entire device with Solidworks was conducted.Force analysis of key components using finite element software ANSYS was carried out and the main components structure was optimized.(4)The motion and stress of soil under four kinds of compactors was simulated with the discrete element software EDEM.The results showed that compression wheel with sharp ridges had the best performance in crushing soil.(5)Experiment study were carried out with factors of operation speed,counterweight and moisture content and indicators of soil firmness and bulk density.The optimum range of parameters were obtained from single factor test and the optimum combination of factors was revealed as speed of 1.3m/s-1.5m/s and counterweight of 16 kg?20 kg from quadratic orthogonal rotation combination experiment. |
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