| Transplanting is an important link in the mechanized rice planting process,and mechanized throw planting is an important method of mechanized transplanting of rice.The existing rice seedling throwing machine has some problems,such as root injury and seedling leakage caused by seedling entanglement,difficult recovery of seedling tray,large space occupied by seedling taking mechanism and small amount of seedling stored by bicycle.In this paper,we design a kind of ejector seedling taking system,and improve the structure of the key parts of the rice seedling throwing machine,taking mechanism and shifting mechanism,which is of great significance for the overall operation efficiency and quality improvement of the rice seedling throwing machine.In this paper,based on the experimental basis of the inherent characteristics of rice pot seedlings,through the selection of schemes,three-dimensional modeling,simulation analysis and field tests,the orderly seedling toppling system was designed.The main research contents of this paper are as follows:(1)Analyze the biological and physical characteristics of rice pot seedlings,measure the quality and size of rice,and put forward the structural design scheme of each part of the rice throwing machine seedling system combined with the preliminary experiment.By comparing the schemes,we choose the end CAM ejection and the intermittent gear mechanism synchronous shifting as the final scheme.The 3D model of the end-effector was established by Inventor software,which provided the basis for the subsequent simulation analysis.(2)Aiming at the proposed scheme of taking rice seedlings by throwing rice seedlings,the principle of taking rice seedlings is analyzed,and the movement and force of taking rice seedlings are analyzed,so as to obtain the main factors affecting the ejecting speed of rice pot seedlings in the process of taking rice seedlings.The taking mechanism,shifting mechanism and transmission scheme of the taking system were designed,and the threedimensional model of the taking system structure was perfected.(3)Simulate and verify the velocity and mechanical model of the ejection mechanism.ADAMS software was used to establish the mechanism model of rice ejecting,set the theoretical parameters,analyze the results and determine the range of ejecting speed.It was found that the camshaft speed was no higher than 90 r/min in the stable process of rice ejecting,and the simulation results verified the rationality of the ejecting mechanism design.ANSYS software was used to analyze the strength and fatigue life of the seedling taking mechanism,and it was found that the maximum stress was far less than the allowable stress,and the fatigue life parameter negram value met the design requirements.(4)Prepare the physical model of the rice harvesting mechanism and optimize and improve the prototype.Taking the rate of taking seedlings,the qualified rate of taking seedlings uniformity and the damage rate of pot seedlings as the performance indexes of the mechanism of taking seedlings,taking the diameter of the ejector rod,the inclination of the seedling plate and the ejector speed as the design variables of the system,single factor test and multi-factor orthogonal test were carried out on the diameter of the ejector rod,the inclination of the seedling plate and the ejector speed.The single factor test results show that the range of seedling parameters is:the diameter of the ejector rod is 11 mm～13 mm,the Angle of the rice plate is 65 °～75°,and the ejector speed is 0.3 m/s～0.4 m/s.The results of multi-factor orthogonal experiment showed that the Angle of seedling plate had the greatest influence on the rate of taking seedlings and the uniformity of taking seedlings,and the diameter of the top rod had the greatest influence on the damage rate of pot seedlings,and the optimal parameter combination was obtained:the diameter of the top rod was 12 mm,the Angle of the bottom plate was 70 °,and the top ejecting speed was 0.35 m/s. |
PDF Full Text Request