The transplanting mechanism is the core working part of the rice transplanter, which realizes the action of transplanting and transplanting. It determines the transplanting quality and efficiency of the rice transplanter. At present, the main forms of transplanting mechanism of domestic rice mobile transplanter are crank rocker type and rotary type. The former can work normally at the working frequency of 200 ~ 220 times / min. with the increase of transplanting frequency, the vibration of transplanter frame will increase; At the same time, the needle speed of the planting mechanism is too high, which will produce defects such as uneven seedling separation, increased seedling injury rate and seedling leakage rate, and vulnerable planting arm, which limits the improvement of work efficiency. The latter is used for high-speed rice transplanter. It is a planetary transplanting mechanism. Two planting arms are connected on the eccentric gear box. The eccentric gear box rotates for transplanting twice a week, which improves the transplanting efficiency and reduces the speed of seedling needle thread. Therefore, the seedling injury rate is low, the seedling separation accuracy is high and the transplanting quality is good.
All kinds of rotary transplanting mechanisms introduced have similar kinematic characteristics, meet the requirements of front transplanting operation of high-speed transplanter, and have the characteristics of low seedling needle speed during seedling picking and high seedling needle speed during return after seedling pushing. The key to forming the “waist shaped” static track of rice transplanting is the non-uniform transmission mechanism. The non-uniform transmission of various rotary transplanting mechanisms introduced is mainly realized by eccentric gear meshing transmission or elliptical gear meshing transmission.
(1) The structural characteristics and motion mechanism of eccentric gear non-circular gear planetary system transplanting mechanism are analyzed, and the kinematic model of the mechanism is established.
(2) Based on the visual VB development platform and kinematics model, the auxiliary analysis and optimization software of transplanting mechanism is independently developed, and the kinematics characteristics are analyzed.
(3) According to the self-developed optimization analysis software, the kinematics model is verified through human-computer interaction, and the structural parameters of transplanting mechanism suitable for the working requirements of high-speed transplanter are optimized. The optimization results are as follows: e = 3mm, r = 19mm, α 0＝－40°， φ 0＝36°，S＝155mm，H＝180mm。
An eccentric non-circular gear planetary transplanting mechanism is designed. The non-uniform transmission is realized by the meshing transmission of eccentric circular gear and conjugate non-circular gear, which can realize the meshing transmission without side clearance. By selecting appropriate structural parameters, the “waist shaped” static track that can meet the working requirements of high-speed transplanter can be obtained, and the requirements of large and small seedling transplanting can be met at the same time.