| Corn is an important food crop in China,which is related to national food security.Due to the climate and planting patterns in the southwestern China,corn has a high moisture content at harvest.The existing corn kernel harvester is less effective in harvesting high-humidity corn.At the same time,there is little research on the degranulation of high-humid corn in the domestic and foreign.This paper points to the problem of high broken rate and high un-threshing rate when the corn kernel harvester receives high-humidity corn,developing a device suitable for threshing high-humidity corn,which improves the quality of harvest.And it can provide a reference for the design and research of small corn kernel harvester in Southwest China.The results of the research are as follows:Through investigating the moisture content of corn in 25 regions of Sichuan and Chongqing,it is found that the moisture content of corn in Southwest China is about 35%.The experimental study on the threshing characteristics of Yayu 988 high-humidity corn showed that the axial direction of the ear of corn should be consistent with or at a smaller angle to the axial direction of the barrel.And the broken rate and un-threshing rate of corn were effectively reduced by using extrusion principle.Based on the 3D drawing software Solidworks and discrete element simulation analysis software EDEM,the simulation design of two kinds of threshing drums was simulated and compared,and the feasibility of the design scheme of the rod-nail-tooth combination threshing drum was determined.On this basis,according to the relevant theory of corn threshing device design,the axial flow roller with radial feed and axial discharge was designed.The drum is 1350 mm in length and 450 mm in diameter,and the threshing element is made of D-shaped rod teeth and 15 mm thick nail teeth.The height of the nail teeth is 75 mm,and the nail teeth are covered with a non-toxic wear-resistant rubber sleeve.The concave plate is made of grid type concave plate,and the concave plate has a corner angle of 180°.The length of the hole between the horizontal plates is 40 mm and the spacing of the sieve bars is 15 mm.The top surface of the grid should be 10 mm above the screen strip,and the corners of the grid should be properly ground and passivated.In order to ensure the safety and reliability of the threshing device,the ANSYS simulation software was used to simulate the structural statics and vibration modes of the threshing drum.Subsequently,the test-making platform of the rod-nail-tooth combined high-humidity corn thresher was developed.The diversion angle,the threshing speed and the threshing gap were selected as the test factors,and the broken rate and un-threshing rate as the test indicators.Single factor testing determines the level of testing.The working parameters of the threshing device were analyzed and optimized by response surface test,and establishing a regression equation.The optimum working parameters of the rod-nail-tooth combined high-humidity corn threshing device were obtained.The result is that the threshing speed is 11 m/s,the threshing gap is 44 mm,and the diversion angle is 16°.Through three repeated verification tests,the average broken rate is 3.97%,and un-threshing rate is 0.15%,which is basically consistent with the theoretical prediction.Compared with the original 4YZ-2 corn kernel harvester,the crushing rate of the harvested grain is reduced by 2.6%,the unremoved rate is reduced by 1.52%,with good design effect. |
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