Design And Experiment Of Rice Straw Reverse Rotation Deep Buried Device

Mechanized returning rice straw to the field was one of the main ways to deal with straw in Northeast China at present.The straw returning machine with reverse rotation operation mode had the advantages of deep ploughing depth,high rate of returning straw to the field and smooth surface after operation,but there were some problems,such as high operation power consumption and grass entanglement by blade roller.In this paper,combined with the operation process of the counter-rotating returning machine,the reasons of high power consumption and grass entanglement of the returning blade were analyzed,and a counter-rotating deep-buried sliding cutting returning blade was designed.In order to achieve better surface smoothness,the counter-rotating returning machine was equipped with a leveling device to complete the deep-buried returning and leveling operations of straw in one operation.After the operation,the surface was leveled,which reduces the operation times of the paddle mixer in spring,reduces soil compaction and soil hardening,and uses theoretical analysis,virtual simulation,experimental design and other methods to reverse the rice straw.(1)Determination of soil parameters and agronomic requirements of straw returning to fieldTaking the working environment in different accumulated temperature areas in Northeast China as the main investigation object,various soil parameters,including soil friction coefficient,bulk density and water content,were determined by physical test measurement,which laid the foundation for the follow-up simulation experiment.Meanwhile,the existing mechanized straw returning modes in Northeast China were investigated,the characteristics and shortcomings of each mode were summarized,and the agronomic requirements of straw returning in Northeast China were put forward,which provided important reference for the subsequent design of straw returning blade structure.(2)Design of counter-rotating deep-buried sliding cutting returning bladeThrough theoretical analysis,the motion equation of sliding cutting angle of counter-rotating returning knife was established.In order to improve the sliding cutting performance of returning blade,Archimedes helix was used to design the side cutting edge of returning blade,and the equation parameters were determined.The dynamic sliding cutting angle of the side cutting edge curve was calculated and verified to meet the conditions of soil-straw sliding out of returning blade.The circular arc curve was used to design the front section of returning blade,and the circular arc radius was determined to be 60mm based on the tillage width and installation angle of the front section.(3)Design of leveling deviceCombining with the working principle of leveling device,the height system and leveling system of leveling device were designed by theoretical analysis,and the relationship between hydraulic cylinder expansion and displacement of leveling shovel was explored,which provides theoretical support for controlling and adjusting the position of leveling shovel.The structural parameters of each part of leveling device and hydraulic cylinder parameters were preliminarily determined.Through mechanical analysis of soil particles,the relationship between bending angle of leveling shovel and welding angle of leveling shovel and stress of soil particles was explored.(4)Simulation Test of Reverse Rotation Deep Burying and Returning to FieldThe EDEM software was used to carry out the simulation control test between the anti-rotation deep-buried sliding cutting returning blade and the traditional returning blade.The results showed that the straw returning rate and throwing performance of the anti-rotation deep-buried sliding cutting returning blade were basically the same as those of the traditional returning blade,and the operation power consumption was reduced by 18.19%.Selecting stubble height,cutter roller speed and machine forward speed for single factor test,the test results showed that there was a significant influence between each factor and machine power consumption.Selecting appropriate factor level and taking operation power consumption as evaluation index for orthogonal test design,it was finally determined that the factors affecting operation power consumption of returning machine from big to small are:cutter roller speed,machine forward speed and stubble height.(5)Field performance test of rice straw reverse rotation deep-buried returning deviceField experiments were carried out in different water content plots in different areas of Heilongjiang Province.The results showed that when the soil moisture content was 20～30%,the surface straw coverage rate was 336～353g/m~2,the tractor operating speed was 1.5km/h at low speed and the blade roller rotating speed was 250r/min,the average tillage depth was over 18cm and the straw returning rate was 87.9.The field comparative test compares the parameters of the anti-rotation deep-buried returning machine with those of the rotary tiller and plough.The field test of the leveling device showed that the average value of the surface roughness after operation was 0.68cm lower than that of the returning machine without leveling device,and the standard deviation was 0.053 lower.After the leveling device was configured,the surface roughness was higher and the stability of the surface roughness was better.