The shovel type seedbed preparation machine is suitable for the preparation of rapeseed seedbeds in the rice-oil rotation area in the mid-lower Yangtze River. It can complete the functions of soil plowing, soil leveling, straw burying, and furrow opening in one operation. However, the unit had large vibration and noise during idling and field operations, which can easily cause wear and tear of key components, reduce work reliability and trouble-free working time, and affect the health and comfort of the driver. In order to solve the problem of large vibration during unit operation, this paper analyzed the theoretical excitation frequency of the main vibration source during the operation of the tractor coupling unit through theoretical calculation, and the vibration acceleration of the unit under idle speed and field operation conditions was tested by using Coco-80 dynamic signal Test and analysis system. By using time-domain analysis and frequency-domain analysis, the vibration acceleration at different measuring points under two working conditions was determined, and the main excitation source of the unit was the movement of the shovel type tillage and soil preparation device. Based on the results of the vibration test, a scheme to reduce the vibration of the shovel type seed bed preparation machine was proposed by optimizing the arrangement of the crank phase angle to reduce the combined inertial force and inertia moment of the machine. According to the mass substitution method and kinematics analysis, the inertial force variation trend of a single group of shovel tillage and land preparation devices was obtained. Base on the calculation results, it was further clarified that the inertial force on the whole machine can be reduced by rationally designing the crank phase angle arrangement of the ten groups of mechanisms of the unit. Based on the calculated inertia force on a single group of mechanisms and combined with the crank phase angle of the existing machine tools arrangement, the inertial force and inertial moment force models of ten sets of crank-rocker mechanisms of the whole machine were established, and the arrangement of the crank phase angle that minimizes the total inertial force and inertial moment of the whole machine was obtained by using MATLAB software. Under this crank phase angle arrangement, the total inertial force of the whole machine was basically balanced, and the average absolute value of the total inertia moment in the x and y axes were reduced by 37.40% and 30.09% respectively. In order to verify the vibration reduction effect of changing the crank arrangement on the unit, the acceleration time domain signal was collected from the improved unit at the place where the vibration was relatively large. Compared with the unit before improvement, the total vibration of the measuring points after the improvement was respectively reduced by 36.42% and 31.97% under the conditions of idle speed and field operation. This research can provide reference for the inertia force balance design of planar linkage mechanisms and the research on vibration reduction of agricultural machinery based on planar linkage mechanism groups.

A large amount of straw and high stubble can often be remained after rice harvest in the rice-rapeseed rotation areas of the mid-lower Yangtze River. It is very necessary to enhance the straw cutting for the high consistency of straw-soil mixing. In this study, an oscillating slide-cutting blade was developed in the shovel-type plowing device. The uniform vertical distribution of straw was also realized within the plow layer for the shovel-type seedbed preparation machine during rapeseed mechanical direct seeding. This blade was used to pre-disturb the soil surface, and then cut the straw before the shovel operation. Thereby the frequency of straw cutting was improved during operation. The structure and working parameters were then optimized in the shovel-type seedbed preparation machine. The edge curve of oscillating slide-cutting blade was then proposed, according to the principle of slide cutting. The dynamic model of straw cutting was also constructed for the oscillating slide-cutting blade. The slide-cutting angles were determined to be 31° to 59°, fully meeting the operational requirements. A kinematic model was also established for the oscillating operation of the blade. A systematic analysis was implemented to clarify the relationship between the dynamic and static slide-cutting angles, crank rotational speed, and forward speed. The angular velocity was finally derived for the oscillating slide-cutting blade in the shovel-type plowing device. Taking the high forward speed (0.9 m/s) and low crank rotational speed (240 r/min) as the critical parameters, the blade edge curve was designed, according to the Archimedean spiral. A simulation was performed on the oscillating slide-cutting blade that installed on the shovel-type tillage device using discrete element method (EDEM) software and multibody dynamics software (ADAMS). Crank rotational speed, forward speed, and blade edge angle were selected as the experimental factors, while the effectiveness of straw cutting and average working resistance were used as the evaluation indicators. Single-factor and three-factor, three-level orthogonal experiments were conducted to analyze the influence of each factor on the test indicators. The optimal combination of parameters was obtained using range and variance analysis. Field experiments were conducted at the rice-rapeseed rotation test base of Huazhong Agricultural University in western China. The experimental conditions were set as the surface after rice harvest, and the soil type was the clay soil. The average content of soil moisture before the test was 26.75%, the bulk density was 1.76 g/mm³, and the average soil cone index at a depth of 0-200 mm was 1 225.3 kPa. The average height of rice straw stubble was 405 mm, with a straw coverage of 1 558 g/m². Field experiment results indicated that all quality indicators of the shovel-type seedbed preparation machine reached the optimal levels after operation. The straw burial rate increased by 3.71 percental points using oscillating slide-cutting blade. There was no significant impact on the tillage depth, seedbed surface, and soil fragmentation rate. In the case of oscillating slide-cutting blade, the proportion of straw shorter than 100 mm increased by 17.09 percental points, while the proportion of straw longer than 200 mm decreased by 20.75%, and the uniformity of vertical straw distribution within the soil was improved by 39.68 percental points. This finding can provide a strong reference for the key components in the tillage machinery.