Research On The Technology Of Single Axial Flow Plate Tooth Threshing Device For Corn With High Percentage Of Moisture

As the first staple grain crop,corn is irreplaceable crop in the development of China’s economy.And currently,China is at the critical stage of transforming the harvesting way of corn ear to directly harvest the corn kernels.Corn threshing process is the most important procedure of mechanized corn harvest process,during which the mechanic parts such as the thresher roller and concave knock and rub the corn ear in order to thresher the corn.However,the moisture content of the corn can influence the physical and mechanical characteristics of corn ear and other kernels,then influence the threshing rate and damage rate.So it’s of significance for our design and construction of threshing devices to master the changing trend of moisture content of corns in the field and the physical and mechanical characteristics of corn kernels with various moisture content.This research tests the physical and mechanical characteristics of corn in harvest period,analyses the threshing principle,conduct field test and simulation analysis on rasp cylinder threshing roller,then use the test simulation analysis software to compare the data of above experiment to analyze the feasibility of threshing function.Then conduct a simulation analysis on designed single and longitudinal axis plate tooth threshing equipment to get the optimum structural parameter.Main contents are as follows:（1）We have conducted a research on the physical and mechanical characteristics of the corn.We monitored the moisture rate of Xianyu 335 corn and Feitian 358 corn in the harvest period,measured the geometric dimension,thousand-grain weight of kernels,mass and density of these two types of corns.We studied the resistance of corn kernels under the status of being laid flat,standing and by the side in the bid to find the changing rules of resistance as the moisture content changes.To provide supporting data for designing the structural parameter of both the single and longitudinal axis threshing detachment device and follow-up simulation experiments,we measured the changing circumstance of the minimum detachment force of corn kernels under various supporting conditions when being put pressure from longitudinal and tangential direction.（2）We have analyzed the threshing principle and design single and longitudinal axis threshing device and compare the field test data with simulation test data to verify the feasibility of the simulation software.Take the single and longitudinal axis threshing roller as an example,we analysis the threshing process and principle and illustrated the major existing form of corn ear during various stages of the threshing process.We created Hertz contact theory model to analyze the causes which influence the critical speed of corn ear to break in the course of collision between corn ear and the threshing element.We conducted a field single-factor test on cylinder threshing roller designed by research group,use AgriDEM simulation software developed by professor Yu Jianqun research group from Jilin University to conduct a simulation test under the same working parameter.Then we verified the feasibility of the simulation analysis software by comparing data to analyze the threshing function of the threshing device.（3）We have designed a kind of plate tooth single and longitudinal axis threshing detachment device.We mainly designed a kind of flexible plate tooth threshing element,adopted the model combined with staple tooth during the detachment period to raise the efficiency of threshing.We putted the trial single and longitudinal axis threshing roller on the testing sample of combined harvester developed by Jilin university to do a field test,and tested the single factor with the threshing rate of corn ear and damage rate of kernel as testing indicator to find the most optimal working parameter range of the twirling speed of the single and longitudinal axis threshing roller,the threshing gap and the forward speed of the sample.We established quadratic regression model to analysis the variance according to the orthogonal test result of three factors in three levels in order to get the result that the most optimal working parameter combination is the twirling speed of the roller reaching 376r/min and the threshing gap stands at 53.2mm as well as the forward speed of the sample with 1.54m/s.Under such conditions,the threshing rate of corn ear is 97.89%and the damage rate of corn kernels is 2.57%,which proves that it’s reliable to verify the model through response surface analysis.（4）We have conducted a simulation analysis on designed plate tooth single and longitudinal threshing detachment device.We used the AgriDEM Simulation software to conduct a simulation analysis on the designed threshing device,then got the parameter model to compare with above article.Then we conducted simulation test on three factors such as roller spin speed,threshing gap and feed quantity on three kinds of levels.We established a twice returning model of corn ear threshing rate and kernel damage rate and adopted the response surface analysis to get that when three test factors are in the stage of zero level,we can observe the influence of the threshing function of the other two factors on the single and longitudinal axis threshing detachment,the changing trend of test indicators and the optimum structural parameter combination.The optimum combination of working parameter is that the roller speed of 39.35rad/s,threshing gap at 41.15mm,feed quantity of 8.1kg/s,corn ear threshing rate at 95.89%and the damage rate of kernel at 3.07%,thus providing data reference for follow-up test research of raising the threshing rate and decreasing the damage rate of the plate tooth threshing detachment device.