Improvement And Experimental Study On Orchard Straw Mulching Machine

The apple dwarf anvil intensive cultivation technology has become the main trend of the world apple cultivation mode.The introduction of this technology has brought a great reformation on apple cultivation pattern.Researching straw mulching mechanization technology and developing orchard straw mulching operation equipment are keys to improve the efficiency of orchard straw mulching technology,and to achieve the high efficient use of stalk resource.Moreover,the technology has important significance on improving water and soil conditions of orchard,and increasing fruit yields and fruit quality.Based on experiment and analysis on the soil covering mechanism and straw spreading mechanism of first generation straw mulching machine used in dwarf apple orchards,the problems existed in the prototype machine and the improvement scheme were put forward.Based on three-dimensional modelling and simulation analysis on main parts of the straw mulching machine using EDEM software,the second generation prototype of the machine was designed,manufactured,and tested.The main works and results of this paper are as follows:(1)The simulation analysis on soil collection box and soil spiral,which were main parts of mulching mechanism,was made by using EDEM to provide reference for their improvement.According to simulation results,the gap of the screw blade was decided as 30°,the rotation speed of the axle was 80~150 r/min,and the inclined angle between shovel blade and shovel surface of the split soil shovel was 123°.Two single curved plate chains were used for transmission and fixation of soil transport scraper.The mulching mechanism was improved and manufactured.(2)Four schemes,i.e.,unpowered transmission belt,vibration chute,shuttle board,and chain scraper were put forward to improve straw spreading mechanism.The chain scraper type was decided as the improvement scheme on straw spreading mechanism.The power of the straw spreading mechanism was 4.58 kW,and the shaft diameter of main transmission axle was 50 mm.BMP-125 cycloid hydraulic motor was used as power source,and WPA125 worm gear reducer was used to transmit power.Three-dimensional modeling and manufacture on material discharge assisted mechanism were done.Moreover,the improved mulching machine was installed integrally.(3)Two factors and three levels orthogonal experiment on straw spreading mechanism was performed.The results showed that a thick covering layer could be obtained with the discharging roll forward,and the rotation speed had a significant effect on the covering thickness.A thin covering layer could be obtained with the discharging roll inversion,and the rotation speed of discharging scraper had a significant effect on the covering thickness.When the forward speed and discharging roll rotation speed were 0.6 km/h and 26 r/min,respectively,the best covering thickness was obtained,with the thickness uniformity coefficient of 98.0% and accuracy coefficient of 96.8%.When the forward speed and discharging scraper rotation speed were 0.8 km/h and 12.3 r/min,respectively,the smallest covering thickness was obtained,with the thickness uniformity coefficient of 96.0% and accuracy coefficient of 95.2%.The width uniformity coefficients and accuracy coefficients at both thick covering layer and thin covering layer reached 100% and 90%,respectively.(4)Binary linear models between covering thickness and forward speed and discharging roll rotation speed(or discharging scraper speed)were built at thick covering layer and thin covering layer.The determination coefficient of the models were 0.979 and 0.985,respectively.The Pr>F values of the two models were not greater than 0.0001,which showed that the two models were extremely significant.It indicated that there were good correlations between covering thickness and forward speed and blanking roll rotation speed(or discharging scraper speed).For thick covering,the determination coefficient between calculated and measured values of covering thickness was 0.941,and the coefficient was 0.922 at thin covering.According to the thickness covering models,straw mulching machine could realize any covering thickness whithin 3.6 cm~13.8 cm when covering mushroom dreg.(5)The experimental results on soil covering mechanism showed that the qualification rate of covering thickness at thin soil covering layer was around 50.0%,and the qualification rate of covering width at thin soil covering layer was higher than 60.0%.