| Crop straw,a by-product of agricultural production,is an important biomass resources and can be used as fertilizer.So the straw returned is conducive to improving the quality of cultivated land,achieving sustainable agricultural development.In Huang-Huai-Hai area,the large amount of maize straw cover resulted in the increasing difficulties in tillage andr wheat sowing,and long-term cultivation resulted in the shallow soil plough layer,an integrated machine was developed to pick up,crush and bury the corn straw at single operation to cope with this problem,using the new tillage technology with ditch-buried straw return to reduce the surface content of straw and improve soil organic content of the deep soil.The main results are as follows:(1)According to the proposed solution of straw pickup-chopping and ditch-burying returning field,through literature analysis and virtual assembly design,the key points of design,such as spring-finger up-throwing straw to the crush device,straw be chopped with a fixed knife and a high-speed rotating knife,the baffle plates placed in the back of the crushing chamber be used to adjust the proportion of the straw to be buried,and sequentially complete ditching,straw-disposing and soil-covering from front to back,were proposed.(2)According to the requirement of picking up the corn straw,the model of the spring-finger cylinder pickup device was determined based on the working principle and the working process analysis of the typical spring-finger cylinder pickup device,and limit condition of spring-finger up-throwing straw was obtained by force analysis on corn straw.Through the simulation analysis,the structure parameters and working parameters of the spring-finger cylinder pickup device are determined.(3)The parameter of the crushing device with a fixed knife and a high-speed rotating knife was completed.Then the 3D air flows in the crushing chamber at different rotating speeds were simulated and analyzed in FLUENT,and the fundamental characteristics about the air field were gained.It was found that the eddy currents occurred at both the inlet and outlet of crushing chamber,and the eddy intensity increased with the increase of the rotation speed,which would have an effect on the entry and thrown of the straw.Using folding line shell can make the velocity and pressure of the air flow close to the shell change sharply,consequently to change the movement statement of straw during the crushing process,and to prolong the crushing time of straw in a certain extent.Thus the crushing degree of the straw can be improved.(4)Using the discrete element method(DEM)analysis of cut maize straw material movement in toss chamber,toss board vane angles,speed of rotation axis and feed rate of straw were simulation by EDEM software.The results showed that when toss board vane angles were 0°and speed of rotation axis was 180r/min,the toss board entirety performance was better,and which can worked under the condition 1.5 times design feed rate of straw(1.1kg).(5)The field experiments results showed that the prototype worked steadily under different ditch-burying percent.In addition,the qualification rate of straw chopping length was 92.6%,the stability of ditching depth was 95%,the average thickness of overbarden was 94.9 mm,and the deviation of tested ditch-burying percent was less than 10%compared with setting value.Conclusively,each technical index satisfied the technical requirements,which had achieved the anticipated goal. |
PDF Full Text Request