| Stubble breaking disc coulter is an important component of conservation tillage machine, mainly used for blocking the stubble breaking and reduce resistance. Currently study of breaking disc was focused on driving disc cutter and experimental analysis, and study on passive disk performance was relatively small, experience design and a lot of field experiments were used in these studies, unable to obtain the accurate design parameters. And in order to determine the optimal working parameters of passive disc coulter, research their working mechanism, provide the basis theory for the product which used disc coulter as working parts, experimental study the influence of working performance by sweep and tilt angle of different types of passive disc coulters on the soil bin was investigated. The main work and conclusions of this paper are as follows.(1)In order to satisfy the test requirements, a testing device with adjustable angle for passive disc was designed. The test bench which was composed of a frame, two depth limiting wheels, sweep and tilt angle adjusting component, disc coulter and other components, could achieve precise regulation of passive disc coulter working and tilt angle. The sweep angle adjusting range was-10°~10° with 1°accuracy, and the tilt angle adjusting range-20°~20° with 2.5°accuracy.(2)Using the Pro/E software, each component of the testing device’s 3D model was created, and assembly was tested by the virtual assembly. Stress components of disc coulter under the ideal situation was analysed, the horizontal and vertical force were respectively 2408 N and 1098 N. According to the stress analysis results, the finite element static analysis of special-shaped frame and frame showed that the maximum deformation of shaped frame and the frame were respectively 1.57 mm and 0.67 mm, the maximum equivalent stress were respectively 680.7kPa and 108 MPa, they were less than the material allowable stress design.(3)After processing the test bench, orthogonal test of results different disc coulters was proceed. The results showed that: the order of factors affecting the stubble breaking rate and resistance was disc type, tilt angle, speed and sweep angle. The optimal combination of passive disc coulter at a given level of the factors was: big corrugated disc coulter with the forward speed of 5km/h, sweep angle of 5°and tilt angle of 2°.(4)Combining the analysis of high-speed photography showed that straw was easy to slip under the flat disc coulter, and hard to slip under the notched disc coulter. The passive notched disc stubble-cutting rate was significantly lower than the active notched disc, the main reason was that the disc notches stubble-cutting performance was low and the edge of the disc played a major role in cutting performance. Effect of turbine disc on ditching and soil crushing was the best, while effect of notched disc was the worst.(5) Both corrugated passive disc and turbine passive disc has good working effect. Straw is more, can choose the turbine disc. When the soil is hard, need to give priority to ensuring the ground, can choose the ripple disc. The turbine disc could be used while surface had much straw; and when the soil is hard, the corrugated disc could be used to give priority to ensuring the open soil.The test device designed in this paper with multi parameter could be adjusted, can provide design reference for the research of other agricultural tools, such as shovel plough, etc. The results of passive discs have a certain reference value for further research and application in disc surgery. |
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