Reverse Design And Tests Of Seedling Picking Mechanism Of Planetary Gear Train Of Combined Gear Transmission With Non-circular Gears

According to the latest data from the World Food and Agriculture Organization,China have already been the most important vegetable producing country in the world,the total domestic vegetable output has reached more than half of the global.As one of the vegetable cultivation methods,Seedling transplanting can improve the yield of dryland economic crops such as vegetables,making full use of sunlight and land resources,improving economic efficiency.Therefore,the research work of the transplanting mechanism,the core working component of the dryland seedling transplanting machine,is particularly important,and it is also significant to the development of China's economy.In recent years,the research group has focused on the research work of vegetable seedlings transplanting mechanism,a variety of planetary gear train automatic seedling picking mechanisms have been proposed.Among them,the combined incomplete eccentric circle—the non-circular gear planetary gear train picking mechanism obtains a large fluctuation of the second unequal amplitude of the transmission ratio in the cycle through the special gear transmission.It solved the problem of large impact of the previous configuration,and became a superior design.However,the mechanism's push posture is still not ideal,the seedling depth is not enough to take the seedlings,and the seedling carried by the seedling arm is easy to interfere with the other seedling arm.Therefore,this paper is based on existing research,optimizing the trajectory of the seedling section and the pusher section in the motion trajectory of the mechanism,increasing the depth of seedlings and obtain better postures.Based on the fitted trajectory curve,a reverse gearing design method is used to obtain a planetary gear train seedling mechanism composed of three combined non-circular gears,four non-circular gears and two seedling arms,and correspondingly carry out the structural design,motion simulation and experimental research of the seedling picking mechanism.The main contents and arrangements of this paper are as follows:1)Expounding the research results and practical application status of dryland vegetable transplanting mechanism at home and abroad,analyzing the advantages and disadvantages of different transplanting mechanisms in design and application.Proposing reverse design for the transplanting mechanism of dryland vegetable seedlings.2)On the basis of the seedling trajectory of the existing mechanism,analyzing the influence of local adjustment of the trajectory on the seedling picking and seeding operation of the mechanism,comparing to select the relative optimal seeding trajectory.Giving N data points on the trajectory,using three-time non-uniform B-spline fitting method,fitting the N+2 control vertices corresponding to the trajectory curve,using the Debord formula to solve the coordinate values of all points on the trajectory curve.3)Convert the new mechanism model into a three-bar mechanism and reverse the total gear ratio of the seedling mechanism based on the fitted trajectory.Calculating the length of the crank and the swing rod in the three-bar mechanism by fitting the coordinates of the seedling track points.Solving the total transmission ratio of the mechanism and assign two-stage transmission ratio,and then solving the section curve data of each gear of the mechanism.4)Complete the structural design of the seedling mechanism according to the result of the section curve,applying UG to draw a three-dimensional model of each part and assemble it into a three-dimensional solid model of the mechanism.Using Adams to complete institutional kinematics simulation and virtual experimental research,improving the rationality and accuracy of component design,as well as design efficiency.5)Drawing the drawings and processing the physical prototype of the planetary gear trainer,carrying out the idling kinematics test and seedling test.Testing the kinematics trajectory when the mechanism is idling,researching institute kinematics of prototype;Using the existing experimental platform to carry out the actual seedling operation test,and analyzing the prototype seedling effect,and verifying the feasibility of applying the mechanism to actual machinery.