Optimization Design And Experiment Study On Hole Of Vertical Disc Soybean Seed-Metering Device

The topic of thesis is based on the National Natural Found Project"The institution innovation and theory research of high-speed precision mechanical soybean mechanism",which based on the theory of falling inside and increasing outside(Item Number:51275086).And the Youth Science Found ProjectThe high-speed operation mechanism research of granule material mechanical quantitative distribution device(Iten Number:QC2010028).It aims at achieving the goal that may meet different sizes of soybean planting by optimizing the shapes and sizes of the vertical disc soybean seed metering device hole.By taking the hole of vertical disc soybean seed metering device as the research object, the hole which can regulate the depth of cavity to change the cavity volume is designed. Thus it realizes the goal that soybean with different dimensions can fill on the premise with unchanging the part of seed metering device. The hole consists of seed spoon, guide wheel and regulation area. Its working principle is that the filling wheel rotates with the guiding wheel coaxially, with the protect plate and adjust baffle between them, by changing the depth of the hole through the radial adjustment of adjust baffle, making the holes of different volumes are suitable for different size of seeds. Seed spoons are distributed uniformly on the filling wheel, the seeds come into seed spoon by the rotating of filling wheel, extra seeds will fall by gravity at a certain angle, the seeds fall into the guide groove without relying at the top of adjust baffle, with the rotating of guiding wheel, the seeds begin to fall to the bottom to complete the process of seeding.As above, the main work is as follows:The properties of soybean. The geometry entity model with statistical significance is build based on different areas seeds. Researching the exterior outline of seeds, extracting the characteristic parameters of surface, obtaining the elasticity modulus-poison’s ratio-the collision coefficient of restitution-friction coefficient and the force and energy of extrusion or shear failure, which all provide the fundamental basis for virtual simulation and experimental research. According to the size and varieties of soybean, the seed is divided into four areas by effective diameter:4.5mm-6mm;6mm-8mm;8mm-10.5mm;10.5mm～13mm。Optimization research of the series sizes of hole. There are so many types of soybean seed, the size distribution is wide, and there are many differences from different soybean seeds, therefore, in order to achieve the purpose of accurately seeding. According to different sizes, the seed will be classification by the traditional mechanical seed metering device. And each level has a kind of metering plate which corresponding to size of the hole, so it increases the cost and inconvenience. One solution is to optimize the size of the hole, with minimal number of metering plate series cover different sizes of soybean seeds. Based on optimizing of the hole, the final design obtained four kinds of plate which makes it can achieve the purpose of covering different sizes of soybean seed.Analysis of basic and assistant structure of the hole. A compound hole of spoon-type structure which can adjust the depth—Combinational compound hole of spoon-type is designed. It makes further solution on the problem that the range of the metering device covering sowing seed size is too small. Through regulating the location of baffle to change the depth of cavity, it can realize the goal that different gears can fill in seeds with different size field. The research deeply on some structure parameters which include proportion of every functional section of cavity, base diameter and inner angle, clears the mode of action and influence rule of seeds structure characteristics on the process of filling the hole and making a comprehensive analysis on the origin of filling forces that seeds can come into the hole and main influence factors. Make a preliminary calculation on the location of adjust baffle according to the area size of seeds, dividing into four gears according to the regulating depth.Virtual simulation of EDEM. Research on mechanism and key technology are put in virtual environments. Building3D model of seed-metering device by building discrete element model of seeds and importing parameters into EDEM to build the element model whose form and characters are same to true seed material samples. Using multi-factor experimental study analyzes regularity of influence on the working performance of the metering device which contains the scoop angle, clearance adjustment and operation speed and establishing corresponding regression equation to makes an analysis on the interaction between various factors and influence law. And using the single factor experiments respectively analyzes regularity of influence on the three factors that affect the working performance of the metering device, analyzing its significance, and determining the optimal parameters of various factors.Test of seed-metering device. Utilize JPS-12computer vision precision metering device test bench to make experimental research, precise seed spacing, qualified index, repeat sowing index, leak index and coefficient of variation are provided, test data and charts which can meet the requirements of national standard are outputted. The sample model is processed based on the hole structure parameters obtained by theoretical analysis and simulation, the experiment verified that the real rationality of each parameter is determined. The contrast test with a series of rows of plate of vertical disk soybean device further verified the adaption of the hole to different size of soybean seed.The research shows that the adjustable depth spoon structure with compound holes which has a wide application range, easy to use and reliable characteristics can not only effectively solve the problem of the small optimum sowing seed size domain, but also can adapt to different sizes of soybean seed filling without replacing device components. there is a one to one correspondence between a seed domain and the control gear, and achieve the purpose of the precision seeding under the improvement of Seed-metering device speed. The gears of the adjust baffle are as follows:1. Adjusting depth of first gear is0;2. Adjusting depth of second gear is2.5;3. Adjusting depth of third gear is3;4. Adjusting depth of fourth gear is5. Gears are respectively corresponding to the four areas of soybean equivalent diameter. By making optimization on each parameter of compound holes of spoon structure at the same time, the best parameter combination of the best result is determined, as camber angle is30°;inner angle is75°;thickness of seed spoon is2mm;angle of seed spoon is30°;cleaning angle is45°.