Theoretical Analysis And Simulation Research On Novel Bionic Corn-ear Snapping Mechanism

According to the statistics, the corn yield has been more than rice and has become thefirst major grain crops in China since2012. And its planting area continues to expand. Withmore and more young labor of agricultural population becoming migrant workers in town,the rest of the agricultural labor feel more and more difficult to complete the high-intensity corn harvest work in a large area. Therefore, the machinery is needed to replacepart of the labor urgently. For traditional corn harvest machine, snapping device most oftenadopt the method of tensile and extrusion to snap corn ear. This way of working is easy tomake extrusion or nibbling on the corn ear caused by snapping roller, leading to the highloss rate at harvest time. Its adaptability to different scion height is poor and recovery effectof complete straw is not ideal. In order to solve the above problems, our research groupimitated the principle of artificial snapping corn ear, adopted bending and breaking modeand designed a new type of bionic corn-ear snapping device. With using the traditionaldesign method, the development of machine requires a lot of manpower, material resourcesand financial resources. Therefore, considering the time and cost of research anddevelopment, I decided to adopt the mode of virtual analysis to complete part of thedebugging work of snapping device.In this paper, based on the previous study, I used virtual prototype technology todetermine the best force direction of bending and breaking force during snapping corn, theclamping position and the breakage condition of corn ear. And simulation analysis wascarried out on the real snapping process and the best working parameters Ire determined.This provides data support for further improvement and development of the late snappingtest bench. The mainly research contents of this paper include the following aspects:(1) Measuring the plant appearance dimensions of Xianyu335corn and establishedthe three-dimensional model combining with the measurement results and actualappearance characteristics with the software of Pro/E, which was similar to the real corn.Then I imported the three-dimensional model to ANSYS software for force analysis. Whencorn straw was held and fixed in different position, its bending force was in differentdirections. From its displacement and stress changes, I can see that: when I held and fixed the tip of corn straw and applied bending force on the top of corn ear downward,component force in every directions can reach the maximum, in this way, the same externalforce can make corn plants produce the maximum deformation in each direction ofcomponent force to realize the corn ear peeling better, so I determined the best forcedirection and the best clamping position. I analyzed that the maximum stress frequentlyoccurred at the upper connection position of stalk and straw. Therefore, I concluded that theconnection position of stalk and straw was the most vulnerable when I applied bendingforce on the top of corn ear downward.(2) Theoretically analyzed the conditions needed to meet when the corn ear peeled indifferent positions. And I used ADAMS software to simulate the structural changes of cornplants when I applied bending force changing with time on the top of corn ear downward.When the external force reached70N, there was a displacement of2.4264mm on theconnection of straw and stalk along the force direction, which can meet the brokencondition of the connection of stalk and straw; When the external force reached90N, therewas a displacement of2.5933mm on the connection of stalk and corn ear along the forcedirection, which can meet the detachment condition to corn ear from stalk. Thus I canconclude that it is easier for the connection of stalk and straw to bend and break than theconnection of stalk and corn ear when I apply bending force on the top of corn eardownward.(3) Simulating the snapping process of the new type of bionic corn-ear snappingdevice with ADAMS and analyzed the collision force generated by snapping rollers to cornear in snapping process. The results show that corn snapping roller speed, corn-feed speedand angle of snapping roller and feed direction all influence the snapping effect, but thecorn-feed speeding among them is the most. And at most two factors of the three factorscan use a value at a higher level. Otherwise, it is difficult to achieve good snapping effect,because the force generated by snapping roller to corn ear is too large or too small.(4) Comparing test results on corn ear test bench and simulation data, I can see thattest results match with the simulation results, so I know the design of simulation parametersis reasonable and the simulation results have reference value. By the range analysis of theexperimental results, when corn snapping roller speed is13r/s, corn-feed speed is1.5m/sand angle of snapping roller and feed direction is40°, I can achieve the ideal snappingeffect and get the relationship function between each factor and snapping rate through theorthogonal analysis of polynomial.(5) I found the shortcomings of the design of test bench in the process of snapping experiment with test bench. So I improved the snapping roller bracket, made the distancebetween the two snapping rollers adjustable and solved the problem of the leakagephenomenon of small corn ear caused by snapping roller fixed position.In this paper, I further analyzed the working mechanism of bending and breaking cornear and simulated the snapping process with the simulation technology of virtual prototype.The simulation results Ire verified comparing with the actual test. They show that thedesign is reasonable. So the research in this paper not only has practical significance, butalso provides a solid foundation for the development of new type of corn snapping device.