| As a high-quality raw material for the textile industry,cotton has high economic benefits.It not only plays an irreplaceable role in in the development of agriculture and the promotion of national economic development in China,but also has great help in adjusting agricultural industrial structure and improving farmers’ economic income.The special planting mode of cotton and wheat intercropping in the Yangtze River basin is a planting system that improves the multiple cropping index and promotes farmers’ increase in production and income.However,the low mechanization degree and high labor intensity of cotton and wheat intercropping seriously restrict the advantages of cotton and wheat intercropping mode to promote farmers’ increase in production and income.Therefore,in order to improve the mechanization degree of cotton-wheat intercropping and reduce the labor intensity of farmers,combined with the agronomic requirements of "one wheat and two flowers" of cotton-wheat intercropping,a cotton-wheat intercropping direct seeding machine was designed,and the key components of the direct seeding machine were studied by theoretical analysis,simulation analysis and field experiment.The research contents are as follows:1.Feasibility analysis of cotton film mulching direct seeder and structural design of the whole machine.According to the agronomic and mechanical requirements of cotton and wheat intercropping pattern,the whole structure scheme of the multi-functional cotton direct seeding machine can be designed,which can be used to complete the mechanical technological process of five operations including fine land preparation,deep bottom fertilizer application,precise seeding,plastic film covering,soil covering and ditch clearing.2.Selection and design of key working parts of the whole machine.The selection and parameter design of the power train,rotary tillage and soil preparation device,copying mechanism,furrow seeding device,furrow fertilizing device,film spreading and soil clearing device were carried out respectively.The whole machine adopts 1WG5.2-80 walking tractor as traction power.The spiral arrangement of the rotary tillage cutlery of the rotary tillage device is installed in the front end of the tractor and three processes of tillage,trimming and leveling of the car surface are completed.The tillage depth is regulated and controlled by the tail wheel.The ditching and sowing device adopts the inner seed filling type and the wing shovel type ditching device.The fertilization device adopts the big trough wheel drain fertilizer device and shoe type ditching device.The copying mechanism is designed at the front end of the seeding and fertilization device to solve the problem of inconsistent depth of sowing and fertilization caused by uneven field surface.Squirrel cage overlaying device was used for film spreading and disc and double-wing furrow clearing plough were used for soil covering.The rolling film pressing wheel and film developing roller spread the film by friction and longitudinal tension,and press the film edge into the film groove.The outer edge of the film was covered by a disc overburden with an adjustable height,while the inner edge was covered by a double-wing overburden furrow plough.At the same time,the double-wing overburden furrow plough was used to clean and repair the damaged ridges after rotary tillage.The whole machine adopts the ground wheel drive,which can effectively solve the matching problem between the forward speed of tractor and the speed of seed metering device,thus ensuring the stability of plant spacing.3.Simulation analysis of key components of cotton film mulching direct seeder.Using the simulation plug-in in the Solidworks software to perform static stress analysis on the rotary tiller,frame,soil cover trenching plough,and fertilizer opener.The maximum stress values are respectively 165.9MPa,20.4MPa,29.65 MPa,5.64 MPa and 56.8MPa are all less than the ultimate yield strength of the designed material,which verifies the stability and safety of the prototype.4.Seeding simulation experiment of cotton seeder based on EDEM.Taking the seed of Ekangmian No.10 as the object,the performance test of the inner filling cotton seed metering device was carried out.Through the simulation of the working process of the inner filling cotton seed metering device and the single-factor test simulation of the effect of the filling hole type on the seeding performance,the structure of the hole is optimized;the depth of the inner hole,the height of the seed inlet and the speed of the seed disc are the influencing factors Through the three-factor and three-level response surface test simulation,the qualified rate of seed metering under the better combination conditions was 98.58%,the missed seeding rate was 0.08%,and the replay rate was 1.34%.Under the condition of excellent combination,the qualified rate of seeding is 95.31%,the missed seed rate is 1.66%,the replay rate is 3.03%,and the error rate from the simulation test is 3.27%(<5%),so the discrete element simulation of seed meter based on EDEM The experiment is feasible to determine the performance parameters of the seed meter.5.Soil slot experiment of cotton film mulching direct seeder.With reference to GB/T5668-2017 and NY/T 987-2006 standards,performance tests were conducted on cotton direct seeders.Test results:The average values of the rotary tillage depth of the left and right rows of the rotary tiller are 105.2mm and 105.6mm,the standard deviations are 2.62 and 2.50,the coefficients of variation are 2.49 and 2.37,and the stability coefficients are 97.51% and 97.63%,respectively.The soil crushing rate after rotary tillage is 92.59%,and the average standard deviation of the flatness is 1.85.The soil crushing effect and flatness are in line with the requirements of live broadcast;the standard deviation of the fertilizer output of the two rows of the fertilizer discharge device is 0.846 and 0.736,the average values are 13.115 g and 13.338 g,variation the coefficients are 6.45 and 5.52,the stability coefficients are 93.55% and 94.48%,respectively;the depth of fertilization in the left and right rows is 93.5mm and 93.2mm,which meets the design standard 80mm-100 mm.In the seed metering device,the qualified rate of the seed charging type seed metering device was 95.12%,the missed seeding rate was about 2.61%,the qualified rate of the hole spacing was 97.0%,and the coefficient of variation of the hole spacing was 20.64%,while the qualified rate of the spoon-wheel seed metering device was 92.8%,and the qualified rate of the hole spacing was 96.67%,all of which were lower than the qualified rate of the internal seed charging type seed metering device.It is proved that the performance of the inner filling type cotton seed metering device is better than that of the spoon wheel type cotton seed metering device.The utilization rate of the daylighting of the plastic film was 92.8%,the longitudinal tensile rate of the plastic film was 6.3%.Each index accords with the design requirement of cotton and wheat set as direct seeding machine.However,the leakage rate of plastic film was 2.29% more than 2%,which does not meet the national requirements. |
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