| As one of the main grain crops in China,rice production capacity has a direct impact on national food security.Rice seedling transplanting technology can increase rice yield and improve rice quality.Compared with the technique of transplanting seedling with carpet seedling machine,the seedling can advance the tiller by one week and increase the yield by 10-20.Therefore,popularizing the transplanting technique of rice pot seedling can effectively improve the production capacity of rice in our country and guarantee the national food security.The key to realize this goal is to realize the mechanized transplanting of rice seedling in bowl,and the seedling delivery mechanism is one of the important working parts of the transplanting machinery of rice,and its function is to transport the seedling accurately for the seedling collecting mechanism.So that the transplanting mechanism can be accurately taken by the pot.The rice seedling transplanter can be divided into horizontal and longitudinal seedling delivery mechanism,at present,Most rice transplanters at home and abroad use the two-way spiral shaft as the core component of the transverse seedling feeding mechanism,and the technology has reached maturity.Using the friction force of flat belt to drive the seedling movement on the high speed transplanter can not guarantee the accurate transmission of the rice seedling by the bowl.Many kinds of vertical seedling feeding mechanism used for transplanting rice bowl seedling at home and abroad have low efficiency.The problems of low precision and complex structure can not meet the requirement of transplanting efficiency of high speed rice seedling transplanter higher than 250 plants / min.In this paper,according to the design requirements of high speed rice bowl seedling transplanting machine,a vertical seedling feeding mechanism suitable for high speed rice bowl seedling transplanting machine is designed.The main work is as follows:(1)Referring to the domestic and foreign relevant literature,summarizing the research status of the longitudinal seedling feeding mechanism of rice planting machinery at home and abroad,and analyzing the technical characteristics and existing problems of the existing longitudinal seedling feeding mechanism in detail.It lays a foundation for the design of this paper.(2)Based on the reasonable design of the original mechanism,a ratchet positioning mechanism is designed.The ratchet positioning mechanism can realize the ratchet wheel unlocking and early falling position locking under the cooperation of the driving rod and the positioning rod,which solves the problem that the current slot wheel mechanism is not in place at low speed.In order to solve the problems such as the difficulty of assembling the original chain transmission and the noise of vibration,the transport mechanism of seedling tray adopts the form of special synchronous belt and steel wire to transport the seedling tray.The longitudinal driving mechanism is mainly composed of intermittent swing bar mechanism and connecting rod mechanism.The kinematics analysis and structure design of the drive mechanism are carried out.(3)Using NX 8.0 software to model the longitudinal seedling feeding mechanism,then the virtual simulation analysis of the longitudinal seedling feeding mechanism is carried out in Adams 2010 software.The rotation state and simulation data of ratchet wheel in the simulation process are observed.The feasibility of the mechanism is verified.(4)Aiming at the existing problems of seedling box and according to the structural form of longitudinal seedling feeding mechanism,the key parts and integral structure of main and auxiliary seedling frame of seedling box are redesigned: a new type of seedling tray positioning support board is designed;Seven independent short shafts were designed to make the seedling box structure modularized and easy to process and assemble.The whole structure of the seedling box was rearranged,the functional function of each part was analyzed,and more lightweight materials were used.The three-dimensional model of seedling box was established and the assembly evaluation was carried out.(5)The physical test prototype was processed and assembled,and the ratchet rotation test was carried out on the longitudinal seedling feeding mechanism.The results were consistent with the theoretical analysis and the simulation results.The feeding accuracy test of the vertical seedling feeding mechanism was carried out on the multi-function test platform designed by our research group.The experimental data showed that the error of single longitudinal seedling feeding was less than ±3mm when the working efficiency was up to 250 plants / min.There was no cumulative error after several longitudinal seedling feeding.The seedling box and the seedling feeding mechanism were observed through the seedling sampling test.The transplanting mechanism was in good coordination and the working performance was reliable. |
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