Hongjun Liu

In order to solve the problems of high forward-resistance and serious soil adhesion in a rice–wheat rotation area, the smooth press roller of a wheat planter in a rice–wheat rotation area was selected as the research object. The low resistance and the adhesion structure of the press roller on a lemniscate-shaped curve were considered, and the geometric design method was adopted to modify the geometric structure of the smooth press roller. A simulation model of the roller–soil interaction was designed using the EDEM2020 software (DEM Solutions Ltd., Edinburgh, Scotland, UK), to investigate the behavior of soil adhering to the surface of the press roller, as well as the effects of the structure and the working parameters on soil adhesion and forward resistance. In addition, the numerical simulation method was combined with the central-plane composite response test scheme to perform the simulation test, using Design-Expert 10.0.4 software (Stat-Ease Inc., Minneapolis, MN, USA). In this test, the forward speed, the axial spacing, and the bulge height were taken as the test factors. On this basis, the working performance of the lemniscate curve type of the press roller was evaluated by establishing a response surface for soil adhesion and forward resistance. With the reduction in soil adhesion and the working resistance as constraints, the optimization was carried out under the condition of a forward speed of 7 km/h. Under a forward speed of 7 km/h, an axial spacing of 40.7–46.8 mm, and a bulge height of 9.3–11.5 mm, the soil adhesion was less than 70 g and the forward resistance was less than 50 N, meaning that the working performance of the lemniscate curve type of the press roller meets the requirements for actual production. In short, this research provides a new idea and reference for the application of a press roller in a rice–wheat rotation area.

According to the conditions of seeding operations in hilly areas of Northeast China, a bidirectional profiling press device (BPPD) was designed. The BPPD mainly consists of a press roller and strength adjusting mechanism which could grant the BPPD horizontal and vertical profile ability. The orthogonal tests L₉ (3⁴) in the field were conducted to investigate the press roller types and operating parameters effects of the BPPD working performance. In the field tests, three kinds of press rollers—rubber press roller (RPR), planar press roller (PPR) and squirrel cage-type press roller (SPR)—were tested under the condition of three spring deformations (10 mm, 20 mm, and 30 mm) and three forward speeds (3 km/h, 5 km/h and 7 km/h). The soil moisture content, average emergence time, emergence ratio, and plant height uniformity were tested as test indexes. Using statistical analysis software, the results of the orthogonal test are press roller type, spring deformation and forward speed have significant influence on the test indexes of soil moisture content, average emergence time, emergence ratio, and plant height uniformity which press roller type have highly significant influence on the average emergence time and emergence ratio index. Using a comprehensive weighted algorithm, the sequence of factors affecting the BPPD performance was determined: spring deformation, forward speed, and press roller type; optimal combination: press roller type PPR, a spring deformation of 20 mm, and a forward speed of 5 km/h.

During the working process of a conventional press roller in the rice–wheat rotation area, the phenomenon of soil adhesion and a large slip rate, which are directly related to the growth and the output of the wheat, occurred widely. It was found that the geometric structure of the back surface was one of the key reasons for Carabus formosus nili exhibiting low adhesion against the soil. In this paper, lessons are drawn from the non-smooth morphology theory and bionics principle. The bionic press rollers with bionically convex hull structures were designed after learning from the geometric structure of Carabus formosus nili, which modifies the geometric structure of the conventional press roller. The three-dimensional simulation model of a bionic press roller and soil was constructed in the ANSYS/LS-DYNA software(ANSYS, Canonsburg, PA, USA) to simulate the dynamic process of the interaction between the bionic roller and soil and to verify the rationality of the design of the bionic press roller. Based on the simulation of the interaction between the bionic press roller and the soil, the main factors affecting the bionic roller were determined: forward speed, load, and structural parameters. The field tests were carried out, and the orthogonal test was used to investigate the effects of forward speed, load, and structural parameters on the operation performance of the bionic press roller. Through the orthogonal test, the primary and secondary order of forward speed, load, and axial spacing were obtained. The optimal combination was: forward speed 7 km/h, load 400 N, and axial spacing 40 mm. This study provides a new idea and reference for the design of a press roller for wheat sowing in the rice–wheat rotation area.