Drive-type ditching device of the high-speed no-tillage direct seeder for rapeseed

Direct seeding has been one of the most efficient cultivation modes for a wide range of plants, such as rapeseed. Among them, the existing ditching device cannot fully meet the practical direct seeding in recent years, due to the low stability of the furrow shape and the seedbeds on both sides of the furrow. In this study, a propeller-type ditching device was designed to actively open the furrows at high speed (≥10 km/h) and simultaneously distribute the soil in the middle and lower reaches of the Yangtze River. A quasi-propeller ditching blade was then proposed, according to the working mode of propellers. The blade arrangement was determined using kinematic and dynamic analysis. The critical parameters (the pitch and edge structures) were also determined to reduce the cutting resistance. A simulation experiment of the blade cutting was carried out using the discrete element model of the blade cutter-soil system. The simulation results indicated that the cutting resistance first decreased and then increased with the increase of the pitch angle, whereas, the rear grinding edge reduced the soil cutting resistance. The quasi-propeller blade group with the optimal combination of pitch angle and edge structure achieved a resistance torque of 176.6 N·m and a traction resistance reduction of 447.7 N, compared with the straight spoon-blade group with a travel speed of 12 km/h and rotation speed of 810 r/min. The dynamic analysis was implemented to determine the curved structure parameters of the soil homogenizing plate. Furthermore, a soil-distributing simulation experiment was carried out using the ditching cutter-soil distributing plate-soil interaction model. The better performance of soil distributing was achieved, when the camber of the left and right distributing plates was 0.19 and the down-inclination angle was 10° and 7°, respectively. The field experiment indicated that the work quality of the overall device fully met the requirements of direct rapeseed seeding when operating at a high speed of 9-12 km/h. An optimal combination was achieved: the furrow depth was 169.1-188.6 mm, the furrow depth stability coefficient was 92.5%-95.6%, the flatness of the furrow surface was 22.2-23.0 mm, the coefficient of variation of soil distributing on both sides was 14.3% and 17.2%, and the stubble burying rate was 81.96%-87.46%, the operating power consumption at the operating speed of 12 km/h was 66.84 kW. This finding can provide a strong reference for the high-speed no-tillage, ditching, and high-quality seedbed preparation for rapeseed in the rice-oil rotation areas of the mid-lower Yangtze River.