Analysis And Experiment Of Backward Rotary Transplanting Mechanism With Eccentric Gears And Non-circular Gears

At present, backward rotary transplanting mechanisms which are the core component of walking-type rice transplanter sold in domestic market are almost crank-rocker mechanisms. We have no independent intellectual property in our country .Meanwhile, the crank-rocker transplanting mechanisms have disadvantages of no-stationary rotation and serious vibration and so on .According to the working requirement of walking-type rice transplanter, planetary gear train with eccentric gears and non-circular gear is applied in the design of backward rotary transplanting mechanism of rice transplanter to create trajectory of the dolphin profile. A new type of backward rotary transplanting mechanism has been designed. The concrete research methods and the results are shown as follows:1)According to the analysis of the working principle of creating trajectory of the dolphin profile by existing crank-rocker mechanisms and backward rotary transplanting mechanisms, planetary gear train with eccentric gears and non-circular gear is used as transmission part to achieve variable transmission.2)Kinematic characteristics of the transplanting mechanism are analyzed, which include transmission ratio of eccentric gears and non-circular gears, relative angular displacement and angular velocity of the planetary gear and relative velocity of the point of seedling needle. Then kinematic model is established.3)According to the kinematics model, assistant analysis and optimization software of the transplanting mechanism based on VB6.0 is developed. Structural parameters of the transplanting mechanism are optimized and the optimal one which meets the working requirement was given by the method of human-computer conversation.4 ) Under the VB.NET environment, using NX Open for.NET procedure development technology to carry on secondary development in UG. Parametric modeling is realized in UG and user interface is made by using VB.NET in which the user can control the parameter variable. The parametric design of parts of the transplanting mechanism is realized. Meanwhile, tooth profile of non-circular gears is calculated by using mixed programming technique of Matlab and VB.NET, which is extruded to be 3D model. Then the parametric design of non-circular gears is realized.5)Virtual prototype model of the transplanting mechanism is built to carry out simulation in ADAMS. Based on kinematic and dynamic simulation analysis, simulation results and theoretical results are compared to verify the correctness of mathematical modeling and whether the transplanting mechanism meets the working requirement or not.6)Kinematic and dynamic characteristics are tested on the test-bed designed for transplanting mechanism of walking-type rice transplanter, whose result is compared with theoretical results.In this paper, backward rotary transplanting mechanism with eccentric gears and non-circular gears is developed, which includes two congruent eccentric gears and conjugated non-circular gears. The optimal parameters which meet the working requirement of walking-type rice transplanter are as follows: e=4mm, R=19.125mm,α₀ = 96°,δ₀ = 84°,φ₀ = 6°, S=180mm, a=38.663mm, m=2.25mm, z=17. Parametric modeling of the transplanting mechanism is realized. The results of virtual prototype test and test-bed test show that test results are almost equal to theoretical results. It is verified that the theoretical model is correct and practical work is reliable.