| With planting area and total output ranking first in the world,rapeseed,is the largest oil crop in China,which has multifunctional development and utilization value for feed,vegetables,fertilizers,flowers and honey.In the middle and lower reaches of the Yangtze River,the main cropping system for winter rapeseed is rice-rapeseed rotation.After the previous rice harvest,the soil is harden and its'moisture content fluctuates greatly,the straw retention is large and its'toughness is strong.Then through traditional rotary tillaging,the rate of straw burying is low and the depth of seedbed is shallow,which is not conducive to seed contact and root deep penetration of direct-seeding rapeseed.In the long run,it will lead to the shallowness of soil tillage layer and the degradation of soil quality.Based on the agronomic requirements of seedbed preparation for direct-seeding rapeseed,according to the production practice of direct-seeding rapeseed in this area,through integrating traditional tillage techniques such as disc ploughing,rotary tilling and furrow ditching,this paper puts forward a kind of seedbed preoaration technology scheme of"left-turn disc plough group burying stubble,reverse rotary knife roll crushing soil,side mounted plough ditching furrow",and designs a kind of driven disc ploughing and reverse rotary tilling integrated machine for rapeseed seedbed preparation,which can realize the functions of surface flatting,seedbed crushing,straw burying,furrow ditching in one operation,and form a reasonable soli tillage layer structure that suitable for the growth of direct-seeding rapeseed.The main research contents and conclusions are as follows:?1?Based on the agronomic requirements of seedbed preparation for direct-seeding rapeseed,the reasonable structure of soil tillage layer and the working procedure of seedbed preparation for direct-seeding rapeseed was analyzed,the objectives of seedbed preparation and the integrated relationship of tilling components was clarified,a kind of seedbed preoaration technology scheme of"left-turn disc plough group burying stubble,reverse rotary knife roll crushing soil,side mounted plough ditching furrow"was put forward,and then the overall design and analysis of the whole machine was carried out,the transmission scheme and technical parameters was determined.?2?The key components design and parameters analysis of driven disc ploughing and reverse rotary tilling integrated machine for rapeseed seedbed preparation were carried out.It mainly includes:?1?Based on the analysis of the horizontal spatial layout between disc plough group and front ditch plough,rotary tillage knife roll and rear ditch plough,it is concluded that there should be a certain distance between disc plough group and front ditch plough in the width of moving soil,and there should be a certain overlap between rotary tillage knife roll and rear ditch plough in the width of tillaging soil.?2?According to the requirements of tillage depth for direct-seeding rapeseed in rice-rapeseed rotation area,the tillage depth of driven disc plough was determined to be 150?180mm,the radius of disc plough was 280mm,the radius of curvature was 560mm,the working deflection angle of driven disc plough group was 27°,the installation space of disc plough blade was 280mm,and the installation quantity of disc plough blade was 4.?3?According to the requirements of ditching furrow in the side of driven disc plough group,the curved surface of the front ditch plough was designed to be half-helix type.The penetration angle of the front ditch plough was 30°,the clearance angle between the bottom of the front ditch plough and the soil was 5°,the angle between the upper end of the guide curve was 83°,the length of the straight-line section of the guide curve was 50mm,the radius of the arc section of the guide curve was 278mm,the aperture of the guide curve was 180mm,the height of the guide curve was 300mm,the initial element line angle was 35°,the minimum element line angle was 32°and the maximum element line angle was 42°.?4?According to the horizontal spatial layout of driven disc plough group and front ditch plough,a compound arrangement pattern of knife blades was put forward,which is composed of lateral and central soil conveying sections I and II.The number of knife blades in the section I was 36,the corresponding blade angle interval was 20°and the helix rising angle was 73°,the number of knife blades in the section II was 12,the corresponding blade angle interval was 60°and the helix rising angle was 66°.The type of universal knife blades in the two sections was IIT245,the installation spacing of knife blades was 81mm,and the composite staggered angle was 90°.?5?According to the agronomic requirements of furrow ditching for direct-seeding rapeseed,the design idea of the curved surface composed of the flipping surface and the shaping surface was put forward.The guide curve shape of the flipping surface was determined to be circular arc,with a radius of 271mm,a height of 320mm,an aperture of120mm,a penetration angle of 30.4°,and an included angle of 71.5°at the upper end of the guide curve.The shape of the guide curve of the shaping surface was broken line,and its'vertical section height was 120mm,its'angle of inclined section is 25°.?6?The kinematic model of the disc plough blade flipping soil towards the side and the rotary knife blade throwing soil towards the back was established,and the critical conditions were obtained.Combined with the influence of the height of the disc plough turning up soil on the actual depth of rotary tillage,the matching design of the speed parameters and the depth parameters between driven disc plough group and reverse rotary knife roller was carried out,and the rotation speed of the driven disc plough was determined to be 94?131r·min-1,the forward speed of tractor unit was 1.72?4.40 km·h-1,the vertical tillage depth difference between driven disc plough group and reverse rotary knife roller was 30mm,and the rotation speed ratio was 3.?3?Field experiments was carried out on driven disc ploughing and reverse rotary tilling integrated machine for rapeseed seedbed preparation.It mainly includes:?1?The results of field working conditions test showed that:The average thickness of surface soil layer was 15.7cm,the average thickness of plough pan was 9.3cm,and the soil firmness was 494.7?1068.3k Pa,the soil moisture content was 20.1?29.7%,the soil bulk density was1.05?1.33g·cm-3 in the range of 0?30cm soil plough layer.The stubble height was239?426mm,with an average of 320.2mm,the straw retention was 1.14-1.73kg·m-2,with an average of 1.39kg·m-2,the straw moisture content was 33.4-51.9%,with an average of40.4%.?2?The results of power consumption test for seedbed preoaration machine showed that:the power consumption of traction,driving and total power consumption were 6.84k W,34.41 k W and 41.25 k W respectively,and the power distribution coefficient was 0.83,which has the characteristics of low traction resistance and high power utilization.?3?The results of the operation quality test of seedbed preoaration machine showed that:the average values of the depth of seedbed,the depth of furrow,the width of furrow,the flatness of surface,the percentage of soil pulverization in seedbed and the rate of straw burying were 173.2mm,190.2mm,401.4mm,11.6mm,95.9%and 90.2%respectively,and the average values of the stability coefficients for the depth of seedbed,the depth of furrow and the width of furrow were 85.6%,86.7%and 84.6%respectively,compared with the traditional rotary tillage,the depth of seedbed cultivation and the rate of straw burying have been improved,which can meet the agronomic requirements of seedbed preparation for direct-seeding rapeseed. |
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