立式驱动浅旋耙设计与参数优化

针对中国黄淮海地区保护性耕作少免耕作业、表土耕作时对地表平整度、表层碎土效果要求较高的特点。研究设计了一种立式驱动浅旋耙,通过对由作业机构参数进行设计优化、刀具的运动学分析与动力学分析,得出了影响土壤受力的因素为机具前进速度与刀具转速,并采用离散元仿真分析对影响因素进行进一步分析。通过田间验证试验,以碎土率、土壤容重、地表平整度为试验指标,对立式驱动浅旋耙进行性能优化试验。结果表明:在前进速度为1.4 m/s,刀具转速为350 r/min时,其碎土率为95.4%,土壤容重为0.82 g/cm~3,土壤平整度为16.3 mm,满足少免耕作业前碎土及秸秆覆盖要求。该研究为少免耕播种前的地表浅旋作业机具提供了参考。

Design and parameter optimization of vertical driving-type surface rotary tillage machine

Aiming at the problems that the characteristics of less tillage in conservation tillage, high quality of surface flatness and high requirements on surface soil erosion during tillage, a vertical drive-type surface rotary tillage machine was designed. The main structure was frame, gearbox, transmission system and rotary knife group of surface rotary. The structure of the whole machine meets the requirements of the topography of conservation tillage in the Huang-Huai-Hai area. And also meets process of loose soil, disturbing and finely chopping the soil. Land preparation without leakage can be done on one operation with vertical surface rotary tillage machine. In order to reduce the vibration of the machine, the knife group adopts the same spur gear meshing rotation form. And the opposite direction of each rotation of gear would reduce the vibration of the machine while ensuring the transmission efficiency and improve the stability during operation. There were 10 knife groups of machine, and each of which had the diameter of 260 mm. The distance between 2 adjacent knife groups was 260 mm. In order to avoid the collision of two adjacent knife group during the operation, the installation angle of the adjacent knife group was 18°. The factors affected the effect of the soil-breaking process were got, which through the optimization design of the structural parameters of the key components, the kinematics analysis and the dynamics analysis of the knife. The factors were the rotation speed of the knife and the forward speed of machine. The camber angle of knife was 10° and the width of the knife cutting the soil part was 40 mm through the kinematics analysis. Discrete element method (DEM) was used to established soil model, to simulated soil broken process with rotary knife. The results showed that rotation speed of the knife and the forward speed of machine had a significant influence on the soil-broken rate and soil fatness of shallow soil tillage. Performance optimization experiment was carried out on the vertical drive-type surface rotary machine through the orthogonal field test. The soil broken rate, soil bulk density and surface flatness used as test indicators. The test was implemented in Donghai country, Jiang Su province in December, in 2017. The test results showed the primary and secondary order of influencing factors for each test index. For the soil broken rate, the soil bulk density and surface flatness, the order was rotation speed of knife, the forward speed of machine. The best structure parameter of vertical driving-type surface rotary tillage machine was obtained through field test. And results also showed that the soil broken rate was 95.4%, soil bulk density was 0.82 g/cm3, surface flatness was 16.3 mm, the coefficient of variation of tillage depth was 12.5%, and the coverage rate of straw was 78.6%, when the forward speed of machine was 1.4 m/s, the rotation speed of the knife was 350 r/min. Results met the requirements of soil-broken and straw covering. This study is provide a new optimization and references scheme for surface rotary rotation machine before no-tillage sowing.