Design And Experiment Of Threshing And Cleaning Device Of Mung Bean Combine Harvester In Hilly And Mountainous Areas

With the increasing demand for mung bean,the planting area of mung bean in hilly and mountainous areas has increased year by year.The research and development and popularization of new varieties suitable for mechanized harvesting of mung bean have greatly promoted the process of mechanical harvesting of mung bean.The hilly and mountainous areas in southern China are small and scattered,the overall terrain is steep,and the soil is sticky and heavy,which is not suitable for the extensive operation of medium and large-scale combine harvesters.However,the traditional manual harvesting has the disadvantages of low work efficiency,high labor intensity and high production cost,and now faces the dilemma of labor shortage.Therefore,designing a combine harvester suitable for mung bean harvesting in hilly and mountainous areas is of great significance to improve the harvesting efficiency of mung bean It is of great significance to liberate the rural labor force and promote the process of agricultural modernization.Threshing device and cleaning device are two core components of combine harvester.Their working performance directly affects the working efficiency of harvester.This paper designs and tests the threshing device and cleaning device suitable for mung bean harvest.The specific research contents mainly include the following aspects:(1)Study on Agronomic and material characteristics of mung bean.The height of the main stem,the diameter of the middle and lower part of the main stem,the length and width of the pod and the grain size of mung bean were measured and counted,and the suspension speed of mung bean grain was measured through the suspension speed test-bed,so as to provide a basis for the design of threshing device and cleaning device.(2)Design and simulation analysis of threshing device of mung bean combine harvester in Hilly and mountainous areas.The working principle of the threshing device was studied,and the axial flow drum threshing device was selected according to the characteristics of mung bean feed.Design threshing drum,threshing element,concave screen and guide top cover.The threshing drum is the core component of the threshing device.The three-dimensional modeling of the threshing drum is carried out by using Solid Works software,and the static analysis and modal analysis are carried out by using ANSYS software,so as to ensure that the structural strength of the threshing drum meets the working requirements.(3)Design of cleaning device and numerical simulation of internal airflow field of mung bean combine harvester in hilly and mountainous areas.The working principle of the cleaning device is studied,and the air screen cleaning device is selected according to the characteristics of mung bean threshing of the threshing device.Design centrifugal fan,combined vibrating screen and transmission device,and determine the size of screen hole.The cleaning devices of ordinary flat louver screen and "f" louver screen with different opening are respectively modeled by Solid Works software,and the internal air flow field of the cleaning devices with two screen structures is numerically simulated and calculated by fluent module of ANSYS 2021 R1 software,so as to analyze and compare the influence of the two screens on the air flow field.The "f" screen is more suitable for the screening out of mung bean mixture than the ordinary shutter screen,and the "f" screen is more suitable for the screening out of mung bean mixture than the ordinary shutter screen.(4)Bench optimization test and field test of threshing and cleaning device.The designed and manufactured threshing device and cleaning device are installed on the threshing and cleaning test-bed of small harvester to simulate the actual harvest of mung beans.The mature mung bean plants are fed into the test-bed for test,and the impurity content and loss rate of mung bean seeds under the combination of different fan speed,screen opening,feeding amount and crank speed parameters are counted.Taking the four influencing factors of fan speed,screen opening,feeding amount and crank speed as the research object,according to the statistical data of bench test,the variance analysis and response surface optimization of mung bean grain impurity content and loss rate are carried out by using design expert software.It is concluded that only screen opening has a significant impact on impurity content and the four influencing factors have a significant impact on loss rate.It is concluded that the optimal parameter combination is fan speed 1617 r/min,The opening of the screen is 23.24 mm,the feeding amount is 0.44 kg/s,the crank speed is 317.53 r/min,and the impurity content and loss rate are 3.11% and 0.15% respectively.Since the parameters cannot be accurately optimized in the actual test,the approximate parameter values are used for field test.The threshing and cleaning device is installed on the combine,and the parameters of the combine are adjusted to the optimal parameter combination for field test.Under the optimal parameter combination,the average impurity content of mung bean grain is 3.84% and the average loss rate is 0.21%.After the difference with the software optimization result,the absolute value is taken,and the relative errors of impurity content and loss rate are 0.73% and 0.06% respectively,which meet the harvest requirements of mung bean combine in hilly and mountainous areas.