| Wheat wide and narrow row sowing can take advantage of side row to effectively reduce crop diseases and increase yield.Aiming at the problems of complex structure and large soil disturbance in the existing trench operation group of wheat wide-narrow row seeder,a wheat T-type trench fertilizer division trench device was designed,which can realize double row seeding and deep lateral application of fertilizer at one time.In this paper,through theoretical analysis and discrete element simulation research,the design and structural parameters of the T-groove ditching device were optimized.Based on the optimization results,the seed-guiding tube bench test and the soil tank test of the T-groove ditching device were carried out to verify the simulation accuracy,and the operating performance of the wheat T-groove fertilizer distribution device was comprehensively evaluated by field performance test.The main research contents and conclusions are as follows:(1)Determination of physical and mechanical parameters of wheat,fertilizer and soil.The material parameters of Xinong 585 wheat variety and Sakefu wheat special compound fertilizer were measured,including particle geometric characteristics,density,static friction coefficient and recovery coefficient,which provided parameter support for the establishment of discrete element model of wheat seed and fertilizer particles.Taking the digital soil groove as the research object,soil intrinsic parameters were determined,including soil particle size classification,density and Angle of reactivity,in order to provide parameter basis for discrete element simulation of T-groove ditching device.(2)Design and analysis of T-groove seed and fertilizer splitting and trenching device.Based on the agronomic requirements of wheat planting in wide and narrow rows,the T-groove seeding and fertilizer splitting and furrowing device was designed and the values or ranges of key parameters were determined,the mathematical model of the structural parameters of the furrow opener on the working resistance was established,and the key parameters affecting the working resistance were analyzed and obtained,namely the entry angle of vertical knifeα,the entry clearance angleεand the slope of the ridge curve f’(x)of the vertical knife and the entry angle of horizontal knifeγ,the swept back angleθand the slope of the flanking curve g’(x)of the horizontal knife.In order to improve the resistance reduction ability of the trench cutter,parabola,exponential function curve and circular arc were used to design the cutter ridge curve,and Archimedean helix was applied to the lateral tool design.In order to improve the uniformity of seeding,the brachistochrone was applied to design the curve section of seed guiding-tube.The motion process of seed grains was analyzed by mechanics,and the key structural parameters of seed tube which affected the horizontal separation velocity of seed grains were obtained,which were the length of the straight section of the seed guiding-tube S and the radius of the brachistochrone r,respectively,and the basic structural parameters of seed fertilizer tube were determined.(3)Optimization of structural parameters of T-groove ditching device.A seed guide tubule-seed particle discrete element model was established,and the influence rule of key structure and working parameters of seed-guiding tube on seed distance migration and seed transverse migration dispersion was explored through single factor and orthogonal experiment.The optimal parameter combination was obtained as follows:the length of the straight-line section of the seed guiding-tube S was 500mm,the radius of the brachistochrone r was 14.71mm,and the working speed v was 4km/h.A soil discrete element model of T-groove ditching device was constructed,and the influence of key structural parameters of vertical and horizontal cutters on working resistance and trench backfill rate was studied by single factor and orthogonal test.The optimal parameter combination of T-groove grooving device is the vertical cutter ridge type is the exponential function curve type,the entry angle of horizontal knifeγis 15°,the sweep angleθis 33.07°,the archimedes helix slip tangent angleτ_nis 53.53°.Based on this,the discrete element simulation is carried out to verify the seed fertilization effect.The results showed that the average seed fertilizer spacing and standard deviation of seed fertilizer spacing were 56.58mm and 5.20mm,respectively.The ditching device could realize the design function of seed fertilizer distribution.(4)Experimental study on T-groove seed and fertilizer splitting and trenching device.The seed-guiding tube was processed and manufactured based on the combination of the optimal parameters of discrete element simulation,and the bench test was carried out.The relative error between the test results and the simulation results was less than 15%,which verified the accuracy of the discrete element simulation of the seed-guiding tube.Based on the discrete element simulation results,the vertical and horizontal cutters with different structural parameters were manufactured and the soil groove test was carried out.The test results show that the influence law of the key structural parameters of the ditching device on the test indexes in the actual soil environment is basically consistent with the simulation study.The relative error between the soil groove test results and the simulation results under the optimal parameter combination is less than 15%.The simulation results can be used to optimize the ditching device,and the performance test of fertilizer and seed discharge was carried out.All the test indexes meet the agronomic requirements of wheat wide and narrow row seeding.A matching wheat seeding prototype was developed and field performance test was carried out.The test results showed that the coefficient of variation of seeding uniformity after operation was 9.5%,the average sowing depth was 4.38cm,the average seed spacing was 9.71cm,the average seed fertilizer spacing was 5.39cm,the average wide row spacing was 20.54cm,and the coefficient of variation of each index was less than 15%.The device can meet the design requirements of double row seeding with one ditch and the agronomic requirements of wheat sowing in wide and narrow rows. |
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