| Vegetables,as the main cash crop in China,have developed rapidly in the last decade and the planting area of vegetables is about 20 million every year.Plug seedling is the main way of modern vegetable seedling in China.Compared with traditional planting,it has high and stable yield,climate compensation and high land utilization.It is the premise of mechanized planting.While reducing labor input,mechanized planting also improves planting efficiency and quality.Mechanized planting of vegetables is the only way to increase vegetable production.But at present,the mechanized transplanting and planting of crops in China is still in the semi-automatic stage.The seedling collection and feeding are all completed by manual work,which has high labor intensity and low efficiency.Therefore,the development of automatic transplanter is imminent,and as the core component of automatic transplanter,and the picking seedling machinery directly determines the overall level of transplanter.It is great significance to study and popularize the picking seedling machinery for improving the mechanization and automation of transplanter.This paper comprehensive analysis the research status of picking seedling machinery at home and abroad.An automatic picking seedling machinery for semi-automatic transplanter is designed.The device has the characteristics of compact structure,stable operation and high efficiency.It solves the problems of artificial seedling feeding and low efficiency of semi-automatic transplanter.The main research contents and results are as follows.(1)According to the working characteristics of multi-claw seedling collection and seedling throwing,the overall design scheme of the dynamic seedling picking device is constructed.Based on the linkage mechanism,the gear-cam linkage mechanism is used to realize the working trajectory of grasping and feeding seedlings,and the cylindrical cam mechanism with direct follower is designed to realize the transformation of seedling picking and seedling throwing position.(2)Establishing the kinematics model of picking seedling machinery,and the design of working trajectory and cam groove theoretical profile curve of cam-linkage is completed.According to the requirement of seedling collection,establishing the mathematical model of cylindrical cam,and the pressure angle and curvature equations of cylindrical cam are deduced respectively.(3)The influence of structural parameters of picking seedling machinery on working trajectory and theoretical contour curve of cam groove are studied.The corresponding objective function is established to determine a set of appropriate structural parameters.According to the actual requirements of seedling collection,the structure of key parts such as cylindrical cam,disc cam and seedling handle of picking seedling machinery are designed respectively.(4)Based on the structural parameters of picking seedling machinery,SolidWorks and Pro/E software are used to establish the three-dimensional model of picking seedling machinery.In ADAMS software,the seedling picking device is transformed into a virtual prototype mode,and the dynamic simulation is carried out.The simulation results of working trajectory,cam follower displacement,clutch cable limit plate displacement and cusp displacement of seedling-claw mechanism are analyzed.The simulation results are compared with the theoretical design,and the results are almost identical.(5)The NC machining simulation of disc cam and cam connecting rod is carried out by Pro/E software,and the physical prototype is assembled.And then the parts of the picking seedling machinery and the test-bed are processed according to the processing simulation program and processing technology.The feasibility of the design method is further verified by comparing the differences of theoretical,simulation and test trajectories through the use of video camera technology. |
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