The Basic Research In The Mechanism Of The New Corn Picker

Maize is one of the most widely distributed food crops in the world, and the planting area of the maize is behind of the planting area of the rice and wheat. Because of the high machine harvesting loss,the poor equipment stability and adaptability,not suiting of agricultural machinery and agronomy etc , the mechanization of maize harvesting has been in the low level . Compared with the wheat harvesting level in 80% and the rice harvesting level in 50%, the maize harvesting level is about 10.6% at the end of 2008. There is a large gap. Therefore, accelerating the development of corn mechanizing harvesting has become a top priority.The capacity of the corn-picking devices directly affects the working efficiency of the corn harvesting machine. Normally, we require the low grain loss, the low grain crushing and the less broken stems. As the work of traditional corn-picking device is depending on the force of stretching and compression on the corn stalk and ear, there is no way to solve the problem that roller-snapping unit squeeze and bite corn. Therefore, based on reducing corn-picking device damage, improving the quality of corn harvesting, we need to re-explore the mechanism of corn harvesting and design the new corn harvesting machine.Introduce the work of four traditional corn-picking device , and analyze the effect of the speed of roller-snapping unit,the diameter of roller-snapping unit,the morphology of roller-snapping unit,the length and the dip angle of roller-snapping unit on Snapping . By theoretical analysis it was shown that the spiral bulge used in most roller-snapping unit could increase the ability to grab the stem , but according to research it was shown that the loss of the corn due to the spiral bulge second crawl the bottom of the ear , and the higher the bulge , the greater the impact . In addition, the base circle of the roller which is continuously rotation could also squeeze and rub the bottom the ear while pulling the stem. When the force of squeezing and rubbing was more than the force of connection between corn grain and cob, corn grain will fall off, resulting in grain loss.Measure the size parameters of corn stalk, and calculate the linear regression equation about the length of corn stalk and the diameter of corn stalk. Design and manufacture the fixture which could hold corn stalk and corn ear. The tensile and bending property of corn stalk and corn ear were examined on WDW-20 electron universal testing machine controlled by computer. By comparing the tensile test and bending test, found that the range of tensile force was about 217N-797N and the average fracture force was 515.58N; the range of bending fracture force was about 10.26N-185.6N and the average fracture force was 56.85N.The bending fracture force was significantly less than the tensile fracture force.By analyzing the relationship of moisture content,diameter and tensile load , found that tensile load was not increase with the increasing of moisture content . Within a certain range, there are two relationships which are positive correlation and negative correlation between the tensile (bending) load and moisture content. When moisture content was close to each other, tensile (bending) loads will have increasing trends with the shank diameter increasing. However, because of the specificity of the biological cell structure and organizational structure, there are also some of the data out of the rules coming from inference. By analyzing the relationship of moisture content and tensile (bending) load per unit area, found that in the first batch of samples when tensile (bending) load per unit area reach peak, moisture content are about 81%-84%.In the second batch of samples when tensile (bending) load per unit area reach peak, moisture content are about 66%. The corn in same species has the same forces.According to the Harvesting Principles of the new corn-picking device, analysis three assumptions of the new devices to take off the ear: The first condition is that the level decomposition of the turning spike force calling on the ear which is produced by turning spike roll is stronger than the level decomposition of the force of Ear shank connected with the ear; the second condition is that, the torque produced by ear fulcrum and the force of ear shank connected with the ear must be weaker than the torque produced by the maximum of turning spike force and the ear fulcrum; The third condition is that the force of ear pulling on the ear shank should be equal to the minimum of the force of the holding device pulling on the ear shank. In order to verify the effect of snapping spike with the new corn-picking device, design the test stand of the new corn-picking device and do theoretical analysis and calculation to verify the feasibility of the test-bed size and structure. Part drawings were processed in a factory and assembled in the laboratory of JiLin University, Institute of Biological and Agricultural Engineering.Do the experiment of breaking spike through the test stand and verify the feasibility of the new corn-picking device. Furthermore analyze the causes of two cases in the process of harvesting: one is that the ear dropped with bract, the other is that the ear dropped without bract. Through observing, verify the infer that the new corn-picking device wouldn't damage the ear and grain and infer that the size of the spike Shank diameter has no effect on breaking spike because that the turning spike roll itself provided enough bending strength and bending angleThis experiment has some shortages in synchronous adjustment of clamping chain, adjustment of clamping chain's location, making the gap between ear track and stem clamping plate blocked by bract easily, the test data couldn't reflect the condition of breaking all corn ears and the effect on harvesting caused by the direction of sending the ear and the angle of track plane.Through analyzing and observing the shortages of this experiment, some improvements should be made: Add the device that can adjust the height of corn stalk and the direction of ear to the sending device; Add Blade-like cutting device to the Ring Bars of turning spike roll in order to break off blocked bract; Improve the shape and morphology of turning spike roll in order to turn spike more stably and efficiently.