Optimization Design And Tests Of Rice Pot-Seedling Transplanting Mechanism Of Planetary Gear Train With Incomplete Eccentric Circle Gear

The pot-seedling transplanting is one of the main ways of the rice planting mechanization,and compared with mechanized-transplanting,it has many advantages,such as seedling early tillering,quick recovery,good orthotropism, higher production,etc.It can improve not only the mechanization level of rice cultivation, but also the rice production capacity by using this technology in China.Therefore, it has an important scientific significance and practical application value to carry out the research of rice pot-seedling transplanting mechanism.At present, the rice seedling transplanting mechanisms developed in China are mostly the mechanisms with bars, which is of longer seedling recovery and not good for tillering. It is also difficult to enhance the transplanting efficiency because of its own defects and strong vibration when it works. The majority of foreign rice transplanting mechanisms represented by Japan generally use three sets of mechanism or device to complete operations of seedling pick-up,conveying and planting respectively. The gear linkage mechanism is used to pick up seedlings,belt conveyor to convey seedlings, and rotary transplanting mechanism to planting seedlings,which causes that the transplanting mechanism is of complex structure, high cost, low efficiency,and high growing seedling requirements, so it is not suitable for rice planting mechanization in China. Therefore, in the paper, a new type of rice pot-seedling transplanting mechanism of planetary gear train with one incomplete eccentric-circular gear and four noncircular gears was proposed. It is of high efficiency and steady drive, and only one set of rotary mechanism is used to complete the above three kinds of actions. The kinematics model of the mechanism was built,and the parameters optimization, virtual simulation and bench tests were also carried out. The main research contents and results are as follows.1) Based on the analysis and research of the working principle of the present rice seedling transplanting mechanism, a gear transmission of variable speed with incomplete eccentric-circular gear and noncircular gear was put forward to be used in the rice pot-seedling transplanting mechanism, then a new type of rotary transplanting mechanism with simple structure and low cost was invented which can complete three actions of seedling pick-up,conveying and planting with high working efficiency and steady drive.2) The working principle of the rice pot-seedling transplanting mechanism of the planetary train with incomplete eccentric-circular gear and noncircular gears was introduced, the kinematics model of the transplanting mechanism was established, and its transmission characteristics was analyzed by using the self-developed kinematics computer-aided analysis software.3) Optimization objectives were set up. The parameter modification guiding optimization method was used to optimize the parameters of the mechanism, and then a set of parameters meeting the requirements of transplanting trajectory and posture, which are R=33mm, e=4.3mm,β=281o,0? =35o,0? =42o, φ0=69, S=155 mm, was obtained by using the self-developed parameter optimization software of the mechanism based on the visualized platform of Visual Basic.4) According to the optimized parameters of the mechanism, the whole structure of the transplanting mechanism was designed, its 3D model was established based on UG8.0 software,and then imported into ADAMS to establish its virtual prototype. The movement simulation of the prototype was carried out, and simulation motion trajectory and velocity curve of the seedling needle cusp of the mechanism were obtained. Compared with the theoretical analysis results, the correctness of parameter optimization method and results of the mechanism were verified.5) Physical prototype was manufactured to be installed on the self-developed test bench for high-speed photography kinematics test. Transplanting trajectory and posture of the mechanism were obtained and compared with the relevant theoretical results. The experimental results are almost in agreement with the theoretical results, which shows that the kinematics modeling and optimization design of the mechanism are correct, and the optimized mechanism can meet the requirements of the rice pot-seedling transplanting. The dynamic test was conducted to obtain the change curve of the bearing force in the X and Y direction, and the vibration characteristics of the mechanism was also mastered.