Effect of rotation direction of knife teeth configuration on clearing straw unit performance for no-tillage and straw mulching precision seeder

Abstract: Stubble clearing units are the key part of seedbed servicing device with rotating rigid cutter. In order to understand the effects of stubble clearing units on working performance and load when the knife teeth configuration rotation direction was different, the structure and the function of the left and right spiral stubble-clearing units were introduced at first, and then the conditions were acquired on the pitch of stubble clearing units through theoretical analysis. Based on this, stubble clearing units were designed about the corn planting of a big ridge and 2 rows, kinematic simulation model was built and kinematic simulation was done. The simulation results verified the correctness of the conditions on the pitch of stubble clearing units. The impact law has been got by comparative analysis, which was as follows: the knife shaft of clearing units moved longitudinally and rotated sidewise; for the 2 stubble clearing units, all knife teeth along the circumference impacted the field one after another according to the order of 123456789, and the impact location sequence of left spiral stubble clearing unit along working direction was 186429753 and the right was 594837261; for single-head knife teeth, impact direction of left spiral stubble clearing unit was the same with working direction, the spacing between adjacent knife teeth was 4 pitches, and the unit adopted jumping impact mode, but the right had opposite impact direction, the spacing between adjacent knife teeth was 2 pitches, the unit's impact mode was push-type, and the 2 units had the same spiral feeding pitch and cutting pitch. In order to acquire the load condition by simulation and do a further theory analysis, the simplified three-dimensional model of left-right spiral clearing units was built by SolidWorks, the intermediate file was exported into ANSYS/LS-DYNA, then the mesh generation was performed and the constraints were added on the model; the driving parameters were set according to actual working condition, the working process of knife teeth soil cutting was simulated, and total force and dispersion of both spiral clearing units on the yoz plane were selected as evaluation indices to do a comparison analysis. The results showed that total force and dispersion of left and right spiral clearing unit were 0.0658 kN, 66.2 and 0.062 kN, 60.1, respectively, and the right was smaller than the left. The results indicated that the right spiral clearing unit had a smaller load and load wave. Meanwhile, field performance contrast experiments had been done under the same working condition and test condition, and the mean value and standard deviation of torsion and stubble clearing ratio were selected as indices to do a contrast analysis. The results showed that the mean value and standard deviation of the torsion of left and right spiral clearing unit were 64.6 Nm, 7.2 and 62.7 Nm, 5.1, respectively, which were the same with simulation results. In the field experiment, the right was smaller than the left, and the stubble clearing ratio of the right was 95.3%, bigger than the left that was 93.8%, all indexes except stubble clearing ratio of the right is smaller than the left, which indicated that the right spiral stubble clearing unit had smaller torque and fluctuating load and had a better working performance. The research has a certain reference value for the research of tillage machine with configuration property.