At present, rice transplanters used in China, such as 2zt-935 rice transplanter produced by Yanji rice transplanter factory in Jilin Province and 2ztd-7428 rice transplanter developed by Zhejiang Province, adopt crank rocker mechanism. Due to the action of mechanism motion inertia force and the existence of seedling pushing device, the force acting on the crank shaft increases gradually with the increase of transplanting times per unit time, It causes frame vibration and accelerated component wear, which seriously affects the quality of rice transplanting, which limits the improvement of work efficiency. In the 1980s, Japan began to devote itself to the research of new planting mechanism to replace crank rocker planting mechanism. The planetary gear train planting mechanism developed by Japan Agricultural Mechanization Research Institute is one of the representatives. The transplanting speed has reached 300 ~ 350 times / min, but the vibration caused by the transplanting mechanism is basically the same as that of the crank rocker planting mechanism.
The planetary gear mechanism is symmetrically arranged as the transplanting mechanism of the rice transplanter. It can transplant rice seedlings twice every rotation cycle. Compared with the crank rocker transplanting mechanism, it has less vibration and has great potential in improving the transplanting times per unit time. There are three types of gear transmission for the mechanism: circular gear transmission, non-circular (elliptical) gear transmission and eccentric gear transmission. The advantage of circular gear transmission is that the processing technology is simple, but the seedling claw is difficult to meet the requirements of seedling picking and transplanting angle at the same time, and the planting plant spacing and mechanism size are too large; The relative motion track of the non-circular gear planetary transplanting mechanism is cashew nut shape, and its working track meets the requirements of seedling transplanting. The seedling picking and transplanting angle of the seedling claw and the height of the closed ring can also easily meet the design requirements, and the work is stable, but the processing technology is complex; Compared with the non-circular gear transplanting mechanism, the eccentric gear planetary system transplanting mechanism has simple processing technology and has similar relative motion trajectory and absolute motion trajectory. Moreover, due to the low speed of the transplanting mechanism (170 ~ 180 R / min), the variation of backlash is also small when the eccentricity is small, and its vibration can be overcome by additional devices.
Therefore, we plan to adopt eccentric gear planetary transplanting mechanism on the developed rice transplanter, so it is necessary to study its kinematic characteristics.