| Rice is one of the main food crops in China.With the continuous improvement of crop yield,the yield of rice straw has increased year by year.In order to avoid the pollution of large-scale burning of straw and fully develop and utilize rice straw resources,it is proposed to directly return straw to the field as fertilizer.As an important rice planting area in China,the technology of returning straw directly to the field is a key promotion technology in Northeast China,which mainly uses agricultural machinery to smash and scatter the harvested straw in the field,or directly bury the whole straw and high stubble straw in the deep soil.When returning straw to paddy fields in northern cold regions,there is a large amount of straw on the ground,and the traditional single axis machines and tools are difficult to adapt to the wet clay soil conditions covered with a large amount of straw,and the operation quality is difficult to meet the actual operation needs.In view of the above problems,this paper combines the agricultural requirements of returning straw to paddy fields in northern cold regions,and conducts research and design on the rice straw double axis returning machine through theoretical analysis,virtual simulation,experimental design and other methods.（1）Based on the field investigation on the working environment of rice fields in the northern cold regions and the research on the agronomic requirements of rice straw returning,combined with the existing research results of biaxial machines and tools and the ph ysical characteristics of rice straw in Northeast China,and taking into account the operating effect and power consumption of the machines and tools,a rice straw biaxial deep buried returning machine is designed by using the biaxial operation mode of front axle forward rotation+rear axle reverse rotation.This working mode of the machine can not only ensure a high rate of straw returning to the field and soil crushing,but also reduce the serious problem of soil blocking in the rear axle operation area through forward rotation of the front axle,providing an important reference for the subsequent structural design of the rice straw double axle deep buried returning machine.（2）According to the working mode of the double axis machine determined in the ear lier stage,the overall structure of the rice straw double axis deep buried returning machine was designed,and the main parameters of the machine were determined to be 2416mm×1240mm×1353mm long×wide×Height),operating width 2100mm,supporting power≥66.2k W,forward speed 1.5km·h-1,front axle knife roll speed 274.2 r·min-1,rear axle knife roll speed 219.4 r·min-1,22 rotary tillage knives,54 field returning knives,and their working principles are described in detail,and the operation process of field returning machine under double axle coordination is analyzed in depth.（3）According to the physical characteristics of rice straw in Northeast China,the key components of the machine are designed.The IIT245 rotary tillage cutter is selected for the front axle positive rotary cutter roll,and the reverse rotary cutter roll of the rear axle uses the reverse rotary deep buried slip cutting cutter specially designed for returning rice straw to the fiel d in northern cold regions.By studying the movement process of soil particles under the action of double axles,analyzing the actual working state of the double axle field returning machine,it is determined that the factors influencing the working process are the front axle speed,the rear axle speed,the horizontal distance between the two axle centers,and the vertical distance between the two axle centers of the field returning machine,thus providing a theoretical basis for the subsequent structural design of machines and tools.Combined with the actual agronomic requirements,theoretical analysis of the early work process and the turning radius of the cutter roll,the horizontal distance between the front and rear cutter shaft centers is determined to be 650mm,and the vertical distance is determined to be 100mm.（4）Taking the black soil of paddy field in the northern cold region as the research object,the basic physical properties of soil particles were measured through physical test methods,mainly including soil density,soil moisture content,soil friction coefficient and other physical parameters,providing theoretical data support for subsequent virtual simulation tests.The work process of the rice straw double axle deep buried returning machine was simulated by the discrete element software EDEM,and the virtual simulation optimization test was carried out.The single factor experiment results showed that the forward speed of the machine,the front axle speed,and the rear axle speed had a significant impact on the operation performance,and the straw returning rate gradually decreased and the power consumption gradually increased with the increase of the forward speed;With the increase of the front axle speed,the straw returning rate graduall y increased,and the power consumption first decreased and then increased;With the increase of the rear axle speed,straw returning to the field firstly increased and then decreased,and the power consumption gradually increased.The multi factor test results showed that when the forward speed was 1.5km/h,the front axle speed was 280r/min,and the rear axle speed was 213.33r/min,the straw returning rate was 90.10%,and the power consumption was 22.43k W.Three repeated tests verified the accuracy of the optimized parameters.（5）Combined with the agronomic requirements of mechanized rice straw return in the one-season rice area of the northern cold land,and based on the results of virtual simulation optimization test,the transmission system of the whole machine is designed,and a series of key components such as the cover,straw fence,etc.are configured.The integrated design of the rice straw double axle deep buried returning machine can be used for returning straw to the field in the wet and sticky soil conditions covered with a large amount of straw in the northern cold region of one season rice region.The processing prototype carries out field straw returning performance tests,Focus on the measurement of straw returning rate,surface evenness,brok en soil rate and tillage depth after the operation of the returning machine.The field test results showed that after the rice straw double axle deep buried returning machine was operated,the straw returning rate was 88.7%～91.2%,with an average of 89.76%;The surface evenness after tillage is 1.8cm～2.4cm,with an average of 2.0cm;The rate of broken soil is 97.7%～98.8%,with an average of 98.2%;The ploughing depth is 16.6cm～19.5cm,with an average of 18.0cm.The field operation effect of the rice straw double axle deep buried returning machine meets the requirements of straw returning.From the field operation effect,it can be seen that the rice straw double axle returning machine has no obvious soil blocking phenomenon in front of the machine on the b asis of improving the operation quality of the traditional single axle machine. |
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