Design And Testing Of An Air-suction Hazelnut Picking And Sorting Machine

Flat European large-fruited hazelnuts(large-fruited hazelnuts for short),have been expanded year by year in recent years in the northeast of China.Due to the low efficiency of manual harvesting and sorting of hazelnuts,and the strong seasonality,the cost of hiring workers is high and the production cost is high.In response to the above problems,this paper designs an air-suction hazelnut picking and sorting device to solve the problem of picking and sorting of hazelnuts.The paper firstly determines the working principle of picking and sorting by statistically analysing the material characteristics of hazelnuts and their admixtures;then designs the overall structure and key components of the hazelnut picking and sorting device;then constructs a physical simulation model,carries out gas-solid two-phase hydrodynamic calculations,analyses the sorting degree of hazelnuts in the admixture,determines the sorting device screen angle,the distance between the screens and the gas The design and trial production of a gas-absorbing hazelnut picking and sorting machine were then carried out,and finally field trials were conducted.The field test showed that the designed hazelnut picking and sorting machine meets the technical requirements of the operation.The main research elements of this paper are as follows.(1)Analysis of the material properties of hazelnuts and their admixtures.The specific gravity of the components in the admixture was determined by means of statistical analysis;the critical suspension speed of the hazelnuts and their admixture was determined by means of a suspension speed test.The order of the suspension speed is: stone > single-fruited hazelnut > fallen leaves,providing technical parameters for the design.(2)Design of the overall structure of the hazelnut picking and sorting machine.The overall structure of the hazelnut picking and sorting machine is determined according to the suspension speed of the individual components of the hazelnuts and their admixtures.According to the force situation of hazelnuts and their admixture in each position inside the sorting device,the principle of the sorting device using three-stage screen plate sorting is determined.(3)Coupled CFD-DEM simulation analysis.Based on the theory and methods of discrete element method(DEM)and fluid dynamics(CFD)the airflow field inside the sorting device is parameterised.The coupled gas-solid two-phase flow simulation of the hazelnut picker-sorting device: the distribution of the material in the sieve plate inside the sorting device,the variation pattern of the airflow velocity and the distribution of the airflow field are simulated.The factors and the horizontal range of the hazelnut sorting effect are determined: the angle of the screen plate is 13°～21°,the gas flow velocity is 10～20m/s,and the spacing of the screen plate is 150～250mm.(4)Hazelnut picking and sorting machine trial and field test.Using gas flow rate,sieve plate angle and distance between sieve plates as test factors and net fruit rate as evaluation index,a quadratic rotation orthogonal combination test was conducted to establish a regression model between net fruit rate and each influencing factor,and the order of the influencing factors was: gas flow rate > sieve plate angle > distance between sieve plates.The results show that the hazelnut picking rate is 88.19 % and the hazelnut net fruit rate is 91.49% when the angle of the sieve plate is 17.13°,the gas flow rate is 18.4 m/s and the distance between the sieve plates is 251.2 mm.