| Corn is the most widely planted crop in the world,and it is widely planted in different regions of the country because of its strong drought tolerance,cold tolerance,barren tolerance and environmental adaptability.However,the characteristics of sloping land seriously restrict the development of precision seeding technology in China,such as high operation difficulty,poor moisture retention ability,and unsuitable for large-scale farming tools.In the northeast of China,sloping cultivated land accounts for more than 60%of the total cultivated land area.As the main crop of sloping cultivated land,the quality of corn sowing directly affects China’s food security.Therefore,it is of great significance to ensure the quality of corn sowing under sloping cultivated land conditions.Precision seeding technology is widely used in seeding operations because of its advantages of nodding,uniform plant spacing and row spacing,and no thinning.At present,the pneumatic seed meter is not suitable for working on sloping farmland cultivated land with undulating terrain due to its complex structure and the need to be equipped with fans and large agricultural machinery.Mechanical seed meter has become the most widely used seed rower in sloping cultivated land because of its simple structure,high reliability and the ability to work with small and medium-sized farm equipment.However,mechanical seed meter has shortcomings such as poor seeding quality,missed seeding and serious seed damage,which seriously restricts the development of precision seeding technology.In this context,this study is aimed at the special working conditions of sloping cultivated land sowing,combining advanced precision sowing technology and duckbill seeder structure in domestic and abroad.This study mainly analyzes the process of seed metering,seed guiding and hole pricking of duckbill seed meter,and design a seed meter which can match the agronomic requirements of slope cultivated land and effectively improve the sowing quality.This research can provide a reference for the corn precision seed meter,enrich the form of the corn precision seed metering device,and effectively improve the Chinese corn seed metering device.mechanization level.The main contents are as follows:(1)Principle analysis and optimal design of seed meterCombined with theoretical analysis and innovative design,the optimal design scheme of corn seed metering device was proposed.A duckbill type corn precision seed meter was optimized and designed,which adopts the operation methods of gravity filling seeds,seed testing and replanting,stable seed guidance and precision seeding to realize sowing.In this study,the structural composition and working principle of each working part are described in detail.Combined with the the characteristics of corn seed material,kinetic energy theorem and other methods,the key components such as the seed plate,intermittent synchronous replenishment device and right-angle seed guide parts were optimized and designed.The main structural parameters include:the rocker rotation center point p coordinate is(60mm,40mm),the rocker end angleλis 17.2°,the return spring limit force F_x is 41.8N,and the angleθbetween the right angle guide part and the inner diameter is 110°.Soildworks software was used to build a three-dimensional model of the seed rower to lay the foundation for subsequent performance simulation,model building,numerical simulation analysis,prototype trial and bench test research.(2)The analysis of the seed metering device performance based on the method of ADAMS-DEMCombined with ADAMS-DEM coupling simulation and single-factor experimental research,numerical simulation research on the performance of piercing and seeding was carried out.The discrete element model of corn seeds was established by three-dimensional scanning.Using discrete element software EDEM and dynamic simulation software ADAMS to carry out numerical simulation coupled simulation analysis and verify the main reasons for missed seeding and repeat seeding in the process of seed metering.By analyzing the soil movement form and the force of the duckbill rocker in the process of piercing,the study determined that the optimal duckbill rocker bending angle was 120°and improved the performance of seeding and piercing.(3)Experimental research on bench performance of corn intermittently supplemented duckbill precision seed metering deviceIn order to explore the influence of structure and working parameters of seed meter on seed metering performance,an intermittent synchronous filling duckbill precision corn seeder meter was manufactured,and the bench test was carried out using the performance testing test bench of the seed meter.Selected the operating speed,operating slope angle,and return spring preload as the test factors,and the seeding qualification index and the coefficient of variation of plant spacing as the evaluation indicators,single-factor and multi-factor tests were carried out.Design-Expert 8.0.6software was used to analyze the test results with a view to obtaining the best combination of operating parameters for the seed rower.On this basis,the conventional seed rower was selected for comparison tests to verify the accuracy of the simulation and optimization results.The test results showed that when the operating speed of the machine tool was 1m/s,the spring preload is 15.6N(type T4,the wire diameter is 1mm,the middle diameter is 7mm,and the original length is 25mm),and the operating slope angle was 12°,the designed The corn intermittent synchronous supplementary duckbill precision seed meter has the best seeding performance,with a qualified index of 98.7%and a coefficient of variation of 10.2%,which is 9.5 higher than the traditional duckbill precision seed meter.percentage points,and the coefficient of variation decreased by 2.4percentage points. |
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