| In annual double cropping area of Huang-huai-hai, it is difficult for the next-crop to seed in wheatstubble fields, the reasons are that there are large amount of straws and higher stubbles, and there is notime for them to decay after wheat harvest. The problem of straw-burning has been caused by shortageof suitable no-till seeders, reducing cost and saving farming time. A new type of no-till precision planterwith straw-covering, used in wheat stubble field, has been designed with the purpose of solving aboveproblems and satisfying the requirement of actual production. Theoretical analysis in details andsystematic experimental research have been carried out, the purpose was not only to solvestraw-blocking, improve working quality but also to reduce cost. It has practical significance and couldprovide equipment and technologyl support for the promotion and application of conservation tillagetechnology. In this paper, the research contents and conclusions are as follow:(1) Trajectory and velocity equations were established througn kinematic analysis of the cuttingblade; Major influencing factors of stubble-cutting pitch was finded out, then structural parameters ofcutting blade were determined according to the mathematical model of relationship betweenstubble-cutting pitch and influencing factors; The structural design of blade assembly and overall layoutof cutting blade were accomplished with balde reasonable arrangement; The qualification which wascontent to the uniformity of stubble-cutting pitch of blade assembly was obtained, and also,mathematical equation used for estimating the performance of straw transport of cleaning and coveringmechanism was set up; Trajectory equation was developed with the kinematic anlysis of straw scatter.(2) The optimal structural and working parameters combination of cleaning and coveringmechanism was obtained, meanwhile, relationship between indexes and each factor was confirmed.The method of four factors and three levels orthogonal test was applied, of which working speed, shaftrotating speed, blade arrangement, angle of straw-covering baffle were selected as factors andstraw-cleaning rate, stubble-cleaning rate, straw-covering eveness, straw-covering width were asobjective function. The optimal combination has been obtained: working speed was3.6to4.5km/h,shaft rotating speed was400r/min, blade arrange was4-3-4, angle of straw-covering baffle was75°, inthe meantime, straw-cleaning rate was90.82%~92.36%, stubble-cleaning rate was92.13%~93.79%,straw-covering eveness was14.88~15.13, straw-covering width was2.97~3.01m. The important effectorders of factors on objective functions were as follow: for straw-cleaning and stubble-cleaning rate, thesequence was shaft rotating speed, blade arrangement, working speed, angle of straw-covering baffle;for straw-covering eveness and straw-covering width, the order was angle of straw-covering baffle, shaft rotating speed, blade arrangement, working speed.(3) The virtual prototype was established using the software of SolidWorks and the principle ofmodular design, in addition, the statics analysis of blade and modal analysis of frame were completedwith the software of ANSYS Workbench. The analysis result indicated that the maximum stress of bladewas497MPa and that was less than the maximum allowable stress of667MPa of blade material;resonance of the frame would not occur for it’s inherent vibration was not consistent with that ofvibration source, so, it could be seen that the strength and stiffness of blade and frame could be fulfilledworking demand.(4) The structural and major parameters of key parts of seeding and fertilizing mechanism weredetermined according to the production condition and agricultural demand. Optimization of threemechanical soybean precision metering devices was conducted with the method of single factorcomparative test, of which working speed was as influencing factor and qualified rate, multiple rate,missed rate, variant coefficient were chosen as objective function. Seeding performance of meteringdevice was assessed by the test requirement of GB/T6973-2005”Testing methods of single precisiondrills”. The experimental result indicated that the seeding performance of spoon-roller metering devicewas better than that of vertical socket-roller and vertical spoon-roller metering device, and qualified ratewas87.8%~98.9%, multiple rate was0.5%~1.1%, missed rate was lower than12%, variant coefficientwas less than16%, while working speed was3to6km/h, theory space was8cm.(5) The optimal working parameters combination of technique-economic of cleaning and coveringmechanism was obtained, simultaneously, relationship between indexes and each factor was found. Acentral composite rotatable orthogonal experimental design was employed, of which working speed,shaft rotating speed, stubble-cutting depth of blade were as influencing factors and power, specific fuelconsumption, slippage rate were selected as objective function. The optimal combination has beenobtained: working speed was4.2to4.6km/h, shaft rotating speed was370~420r/min, stubble-cuttingdepth of blade was20mm, at the same time, power was18to20kW, specific fuel consumption was lessthan0.46, slippage rate was less than15%, furthermore, the best mating power was20~22.06kW. Theimportant effect orders of factors on objective functions were as follow: for power, the order was shaftrotating speed, stubble-cutting depth of blade, working speed; for specific fuel consumption, the orderwas stubble-cutting depth of blade, working speed, shaft rotating speed; for slippage rate, the order wasstubble-cutting depth of blade, shaft rotating speed, working speed.(6) The performance test was put into effect refering to the “No-till Planter Type Selection Testsyllabus” and performance test projects and methods of no-till seeder, and JB/T51017-1999“QualityClassification of Precision Seeder for Intertilled Crop” was used to evaluate seeding performance. Theresult manifested that qualified rate, multiple rate, missed rate, variant coefficient satisfied therequirement of superior class, qualified rate of sowing depth attained the requirement of first class,under the condition that working speed was4.5km/h, theory space were6cm and8cm, theory sowingdepth was3to5cm; when stubble-cutting depth was20to30mm, only one time of slight blocking happened, and straw-covering rate of seeding field surface was more than98%; there was no seedswithout soil-covering, and field seedling rate was as high as90%above.(7) Under the condition of large-scale working, field production test was conducted in Xuchangand Shunyi with the purpose of detecting the seeding quality, adaptability, reliability, and so on. Theresult showed that average productivity and reliability was3.9mu/h and0.955, respectively; Comparedwith traditional seeding mode, average seeds number per plant increased by3, average plant number permu increased by6668.5, average thousand kernel weight increased by39.9g, average actual yieldincreased by141.15kg, the cost per mu was saved by35.5yuan, yield value increased by564.6yuan/mu,net income ratio was as high88%above. |
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