Design And Experiment On Vibratory Fruit Harvesting Mechanism With Three-dimensional Excitation

China is a big country in fruit planting,production and consumption,and fruit harvesting has been the most important link in the process of fruit industrialization and scale development.The condition of fruit harvesting in mechanization production technology still lag behind,compared with the development of fruit planting industry.It is serious especially in harvesting season with strong seasonality and labor intensity.At present,the mechanized fruit harvesting equipment actually is inefficient and has great damage to fruit during the harvest compared with artificial harvesting.In order to solve the problems existing in the mechanical harvesting of the fruit,improve the recovery rate with harvesting machine and reduce the damage to the tree in the process of harvesting,a innovative harvesting machine with three-dimensional excitation is designed and analyzed.Firstly,the fruit trees are modeled by software,and the dynamic simulation of the fruit tree model under different combinations of eccentric block excitation is carried out.Then,according to the simulation results,a combination eccentric block three-dimensional excitation fruit harvesting machine is designed.Finally,the prototype was processed for dynamic response test and the actual harvest test to verify the actual three-dimensional fruit harvesting machine harvesting effect.The main contents of the dissertation are listed as follows:1.The excitation form of eccentric block formed by different combinations was analyzed.The finite element model of fruit tree was established in finite element software ANSYS,and the harmonic response analysis was conducted.The frequency of obtaining the maximum vibration acceleration response of fruit tree model was about 22 Hz.Based on this,the vibration simulation of different excitation positions in the fruit tree model was carried out for three types of excitation with different combinations of eccentric blocks.The simulation results show that using the three-dimensional excitation with the combination of vertical eccentric blocks in space,the vibration is excited at the bifurcation between tree branches and tree branches,and the vibration acceleration response is the most uniform,which can produce effective vibration to fruit trees.Then,the effect of fruit trees under different rotational speed ratio of eccentric vertical block combination was analyzed.It was found that when the speed ratio was 1: 1,the acceleration response of fruit trees was the largest and the distribution was more even.Finally,the conditions of fruit exfoliation were analyzed to determine the theoretical conditions for the fruit to fall off with the three-dimensional excitation of the vertical eccentric block combination in space.2.According to the results of dynamic simulation of the fruit tree model under different combinations of eccentric block excitation,the whole structure of three-dimensional excitation fruit recovery machine with the combination eccentric block was carried out.The steady state response of the vibration system is obtained through the establishment of three-dimensional exciter-tree dynamics model.The mass moment of the eccentric block which is the key part of the harvester was 0.56 kg · m,and the structure size of the eccentric block was calculated based on the vibration amplitude of fruit trees under the action of three-dimensional excitation recovery machine.In order to increase the stability of the clamping mechanism and the clamping range,the clamping mechanism of the harvester was finally designed.The required clamping force of the clamping mechanism is 1146.6N and the clamping range is 50 ~ 140 mm.3.In view of the power system of harvesting machine,the hydraulic system of collecting machine is designed.In order to meet the actual needs in process of harvesting,the basic circuit of the hydraulic system was designed to complete the control of the actual power system of the harvester.The parameters and types of core implementation components in the hydraulic system were calculated and selected,and the performance of the hydraulic system was checked,the system of pressure loss and heating temperature were proved in the safe range.Finally,the feasibility simulation of the hydraulic system is carried out by AMESim software.The results show that the working performance of the hydraulic system of the harvester is stable and meets the actual working requirements in vibration harvesting.4.Trial production of fruit harvesting machine with a combination of eccentric block three-dimensional excitation,and three groups of outdoor experiments were carried out respectively.First of all,under the same test conditions,the vibration response comparison test is carried out with the eccentric motor,and the results show that the coefficients of variation of average vibration acceleration of tree body are 0.15 and 0.37,respectively,when excited by three-dimensional excitation pick-up machine and eccentric motor.Three-dimensional excitation can make the fruit tree produce effective vibration with uniform distribution compared with two-dimensional excitation;Secondly,the vibration response test of fruit harvesting machine with three-dimensional excitement was carried out in ginkgo tree,and the results showed that all the branches on the ginkgo tree could obtain larger acceleration peaks,which validated the exciting effectiveness of the three-dimensional excitement fruit picker;Finally,a field harvesting test was conducted,and the three-dimensional excitation fruit harvesting machine speed is 470 r / min,working time is 10 s,pomelo recovery is 76.5%,which can basically achieve the effective collection of pomelo.