| China is the most important producer of rape and vegetables in the world.As the main planting mode of vegetables and other dryland economic crops,seedling transplanting is beneficial to improve the comprehensive efficiency of production.But the dryland plug seedling transplanter has a slow development.Agricultural equipment is listed as one of the ten major breakthroughs of Made in China 2025.So,it has become more and more urgent to strongly promote the research and development of dryland plug seedling transplanter,which is also of great significance for our country to smoothly implement the strategy of building a strong manufacturing nation.In the paper,a new type of rotary seedling pick-up mechanism of planetary gear train with combined incomplete eccentric circular gear and non-circular gears which was invented by the researcher of our group was taken as the research object.The following research contents of the seedling pick-up mechanism were completed,such as the improvement of the kinematics model,the establishment of dynamics model,the analysis of kinematics and dynamics,dynamics simulation,dynamics performance optimization as well as the related experimental research,which will provide the theoretical and experimental basis for the research and development of dryland seedling transplanter with independent intellectual property rights and superior performance in the future.The main research contents and results are as follows.1)Based on the previous studies,the method of curve fitting was used to obtain the mathematics equations of tooth profile curve of the meshing part between the central incomplete non-circular gear and the middle incomplete non-circular in the seedling pick-up mechanism.The equations of displacement,velocity and acceleration for key points of the mechanism were established.Then the kinematics model of the mechanism was improved and the kinematics theory analysis results of the mechanism was obtained through program solving.2)The methods of dynamic static analysis and the dynamics equation group sequencesolution were used to carry out dynamics modeling and analysis of the mechanism to study its dynamics performance.The dynamics analysis software was compiled independently to solve the dynamics model of the mechanism to obtain forces of the moving members and the kinematic pairs.According to the movement of the mechanism,the dynamics analysis results were explained,and the dynamics performance comparison between this mechanism and the other seedling pickup mechanism invented before by our group was made.3)The virtual prototype of the seedling pick-up mechanism was established,and the mechanism dynamics simulation was carried out by using Adams software.The simulation results were compared with the theoretical analysis results,which verified the correctness of the dynamics modeling and theoretical analysis of the mechanism.4)After the dynamics test scheme of the seedling mechanism was designed and the test bentch was set up,dynamics tests were conducted to study the dynamics performance of physical prototype of the mechanism.The bearing force in the x and y directions of the mechanism under the rotary speed of 60 r/min was obtained.The dynamics test results was compared with the dynamics theoretical results of the mechanism.It is proved that the mechanism has better dynamics performance through comparison and analysis to another vegetable seedling picking-up mechanism designed before by other researcher of our group.5)A scheme was proposed to optimize the dynamics performance of the seedling pick-up mechanism by adding balance weight which was determined through calculation.The Adams dynamics simulation analysis was conducted,and the balance weight was manufactured and assembled on the mechanism physical prototype to carry out dynamics tests.The results before and after the optimization were compared,showing that the dynamics performance of seedling pick-up mechanism was improved. |
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