Study On Mechanical Properties Of Corn Kernel And Design Of Threshing Test Bed

Grain planting pattern of Huang-Huai-Hai region was winter wheat and summer corn planted annually.In the process of the corn kernel mechanized harvest,the high moisture content of corn kernel led to high cracked grains rate.Corn kernel mechanical properties and moisture content and structure of threshing unit are important factors for cracked grains rate.In order to increase the level of corn kernel mechanized harvest and research the influencing factors that related to cracked grains rate.Therefore,the mechanical properties of corn kernel with high moisture content were researched and designed a corn threshing test bed with tangential flow and axial flow.The main research works included the following aspects:Experiments were conducted on six corn varieties which have good qualities of the corn kernel mechanized harvest for research the mechanical properties of corn kernel,such as Qiao Yu 8.The three-axis size,ball degree,thousand-grain weight,volume,density,maximum crushing pressure and elastic modulus of corn kernels were obtained.The three-axis sizes of corn kernel decreased with the moisture content decrease.The mechanical properties of different maize varieties were analyzed.Results showed that the maximal crushing pressure and elastic modulus of different varieties maize kernels were negatively correlated with moisture content.The maximal crushing pressure and elastic modulus of different maize varieties also had significant difference.Linear regression analysis of the maximum crushing pressure data and elastic modulus data were carried out respectively.A regression model for moisture content maximum crushing pressure and elastic modulus was established.Design the corn threshing test bed with tangential flow and axial flow used Solid Works software for resolve the question of high cracked grains rate.The threshing test bed contented power and transmission system,transport system and threshing system.Threshing cylinder was designed as nail type and threshing rotor was design as nail type and plate type.The concave was designed as grid concave plate.The feeding rate could be adjusted by adjusting the line speed of the conveyor belt roller.The drum speed could be adjusted through the inverter.The dynamic balance simulation of axial-flow drum and tangential-flow drum was carried out by using ADAMS software.Results showed that the axial-flow drum and the tangential-flow drum conformed to the mechanical vibration constant(rigid)rotor balance quality requirements.In order to verify the vibration safety of the axial-flow threshing drum,the modal of the axial-flow roller under free state were simulated by using ANSYS software.Results showed that the axial flow roller was stable.The threshing experiment of Qiao Yu 8 maize ear was carried out by using the designed threshing test bed.Experiment results showed that the threshing capacity of the tangential flow drum and the axial flow drum was equal under 28% moisture content and the threshing ability of the tangential flow drum was weaker than the axial flow drum after the moisture content was above 28%.Linear velocity of cylinder and the moisture content of corn had a great influence on the cracked grains rate.Through the threshing test,the optimum threshing parameters of the test bench were determined.Analysis of the relationship between mechanical properties and crushing grains rate.showed that the maximum crushing pressure and the elastic modulus of maize kernels were negatively correlated with crushing rate.The cracked grains rate of corn grains decreased with the maximum crushing pressure and elastic modulus increased.When the maximum crushing pressure was 400.55 N,the elastic modulus was 303.75 MPa,the tangential flow drum was 18.03 m/s,the cracked grains rate was 3.9% which was accorded the technical conditions of maize grain harvesting.