Design Of Multi-stage Tangential Roller Threshing Device For Buckwheat Breeding

Buckwheat is a high-yielding multigrain crop that is widely grown worldwide.In terms of production and acreage,China is the world’s largest buckwheat producer.On the other hand,buckwheat is not only rich in carbohydrates,proteins,fats,etc.like wheat,but also contains a lot of fiber,vitamins,and other nutrients,which can not only prevent obesity,but also digest fat and promote the operation of the spleen and stomach,with excellent nutritional value.With the improvement of people’s living standards,the pursuit of high-quality and high-nutritional value buckwheat varieties has gradually developed and expanded.The harvesting and production planning of different breeding communities is a key link in breeding operations,but now the traditional manual harvesting method is also adopted,which is not only not conducive to the development of the breeding industry,but also the results will be interfered by the subjective factors of the harvester,which in turn will affect the subsequent production measurement and production,so it is urgent to carry out research on buckwheat breeding and harvesting machinery.In the harvesting equipment of breeding machinery,the threshing device is one of the main working parts,which must not only ensure the threshing effect,but also ensure that after the threshing of each plot,no residual grains are allowed in the threshing device,which in turn affects the yield of the plot and produces mixed seeds.Therefore,based on reviewing and analyzing the research status of breeding and harvesting machines at home and abroad,this study carried out the research of buckwheat breeding and harvesting devices,focusing on the design of buckwheat threshing system and threshing system self-cleaning.The main contents of the thesis include:1.The biomechanical properties of buckwheat such as crop morphology,stem,and grain characteristics,as well as the mechanical properties during threshing operations,were analyzed.2.The multi-stage shearing drum working mode is proposed to solve the problems of easy entanglement and blockage in the threshing process caused by the inconsistency of buckwheat ripening period,and the overall structure of the modification device is designed,including the frame,feeding wheel,main threshing device,secondary threshing device and discharge device,concave plate,etc.3.The indoor performance test of the designed multi-stage shear threshing mechanism was carried out.The effects of main threshing drum speed,threshing gap and feeding amount on grain loss rate and breakage rate were calculated by single factor method.The results showed that the grain crushing rate was lowest when the drum speed was 600 rpm,the threshing gap was 7 mm,and the feeding speed was 1.2 kg/s.The grain loss rate is lowest when the drum speed is 700 rpm,the threshing gap is 9mm,and the feeding speed is 1.2 kg/s.4.According to the results of single-factor test,taking threshing drum speed,threshing gap and feeding amount as influencing factors,and taking loss rate and crushing rate as the target factors,orthogonal design was carried out and the test was carried out.According to the results of the study,when the drum speed is 600 rpm,the feeding amount is 1.2 kg/s,and the threshing gap is 9 mm,the grain loss rate is the lowest,and the threshing scheme with the lowest grain crushing rate is the drum speed of 600 rpm and the feeding amount is 1.2 kg/s and the threshing spacing is 9 mm.5.The self-cleaning system is designed to realize the removal of residual grains in the threshing drum.According to the structural characteristics of the threshing drum,according to the single air inlet air speed range of 2.5～6 m/s,5 air inlets calculation,the basic parameters of centrifugal fan and fan blade installation angle and other parameters are obtained.6.For five different air inlet positions,set the inlet speed of 3 m/s,3.5 m/s,4 m/s and 4.5m/s and the main threshing drum speed of 300 rpm 350 rpm,400 rpm and 450 rpm,simulated using Ansys Fluent 2022 software.In order to evaluate the simulation effect and provide a reference for follow-up work,a standard line was specified under the threshing drum,and 50 points were selected on this standard line,and the optimal inlet position,inlet air speed and rotation speed of the main threshing drum of the self-cleaning system were selected by counting the ratio of the maximum number of points above the suspension speed of buckwheat and the point value below the minimum suspension speed of buckwheat.The results show that at inlet position 1,the inlet air velocity is 4 m/s,and the main threshing drum speed is 450 rpm,the ratio is 1.38,which is the largest of all combinations.