Design And Experiment Of Device With Throwing And Covering Soil For Straw Mulching In Orchard

The application of straw mulching technology in arid orchard has many advantages,such as increasing soil carbon,reducing evaporation and conserving soil moisture,restraining weeds and reducing soil erosion,The development of equipment suitable for this technology is the key to realize mechanization of straw layer mulching in orchard and efficient utilization of agricultural waste,and is also an important way to improve orchard soil and develop ecological and organic orchard industry in arid areas.Based on the requirements of dense anvil cultivation techniques,straw layering and agronomic techniques,this paper studies and analyses the covering device of straw mulching machine developed by the project team in the early stage.Based on the goal of simplifying the structure and improving the quality of operation,a throwing covering scheme was put forward,and the covering device was redesigned.Based on the discrete element method(DEM),the throwing wheel,which is the core working part of the covering device,was simulated and analyzed,and the structure of the throwing wheel was determined and the operation parameters were optimized.Designed and developed the bench test device,and carried out the field test on the throwing wheel,verified the simulation test results and provided the basis for the development of the prototype of the covering device.The development of the covering device was completed,and the covering quality and power consumption of the covering device were tested,which fully meet the requirements of the covering of the straw mulching machine in orchard.The main conclusions are as follows:(1)The agronomic and mechanical requirements of dwarf orchard straw mulching machine were studied.A double-sided throwing soil covering device was put forward,which is suitable for straw-soil layered mulching in orchard.Three schemes of curved blade type,blade knife type and rotary tillage blade type are put forward for the throwing wheel,which is the core component of the device.Through theoretical analysis of the throwing wheel,it is known that when the throwing wheel adopts bottom throwing mode,the diameter of the throwing wheel D=400 mm,and the number of blades of the throwing wheel is 6,the throwing wheel can meet the operation demand of covering.(2)The results show that the covering effect is better when the width of the blade is 10 cm,the torsion angle of the blade is 0 and the chamfering angle of the blade is 20.The rotational speed,the depth of the soil and the angle of throwing soil are the significant factors.The rotational speed of throwing wheel has the most significant effect on cover width,and the depth of soil has the most significant effect on cover thickness.In the stable operation stage,the uniformity of cover width of soil layer is 100%,the leakage coverage rate is zero,the maximum cover width is 241.2cm,and the cover thickness is 22.0-42.0mm adjustable.(3)Two schemes of throwing soil bench test device,roller type of guide rail and suspension type of sliding groove guide rail,were put forward.The suspension type of sliding groove guide rail is determined to be the bench test device scheme.The bench test device was developed and the test of the throwing wheel was carried out on the spot,the results show that the rule of throwing soil in the bench test is consistent with that in the discrete element test.The maximum cover width is 251.3cm,and the cover thickness is 23.2-40.7mm adjustable,which meets the requirements of operation.A quadratic regression model was established between the width and thickness of the cover and the rotational speed,depth of soil and angle of the throwing soil.The determinant coefficients of the model were 0.9753 and 0.9682.(4)Based on the results of discrete element simulation and bench test,the prototype structure was optimized,and the development and debugging of the device of throwing and covering soil were completed.The throwing wheels on both sides are arranged in dislocation before and after each other.The working width of the hydraulic telescopic adjusting throwing mechanism is adjustable,and the covering width is limited to 1.4-2.2m.BMR100 hydraulic motor is directly connected with the throwing wheel to improve the transmission efficiency.A soil cutter is installed at the soil-facing end of the blade of the throwing wheel,which improves the operation performance and coverage quality of the covering device and reduces the operation energy consumption of the device.(5)Covering test was carried out on the covering device and the results show that the uniformity of width is 100%,the thickness uniformity is greater than 94.6%,the thickness accuracy is greater than 94.9%,the leakage rate is zero,and the covering thickness is 23.2-40.7mm adjustable,which is basically consistent with the results of discrete element simulation test and bench test.A quadratic regression model was established between the thickness and the rotational speed,the depth of the soil and the angle of the throwing soil,and the coefficient of determination was 0.9757.The coefficient of determination between the calculated value of thickness model and the measured value is 0.9569.In the covering operation of the covering device,the thickness of soil layer can be obtained by adjusting the rotational speed of the throwing wheel,the depth of the soil and the angle of throwing soil.(6)The power consumption test of the soil cover device shows that adding the soil cutter can effectively improve the soil cutting performance of the throwing wheel,reduce the resistance moment and reduce the operation power consumption.The average torque and power required in the operation of the single side throwing mechanism are 42.21-91.28 N.m and 1.05-2.33 kW.The peak torque and power are 160.74 N m and 4.18 kW,there are too many random factors that influence the peak torque and power,the peak data are only for reference.