外文翻译=牧草小区播种机排种器的设计及试验=4400字外文文献

本科毕业论文（设计） 外文原文 题目： 小型播种机的设计 学 院： 机电工程学院 专 业： 机械设计制造及其自动化 班 级： 学 号： 姓 名： 指导教师： Development and experiment of seed metering for grass plot Seeder Yang Song, Zhang Shumin, Yi Jintao, Weng Qiang (College of Engineering, China Agricultural University, Beijing 100083， China) Abstract: In order to develop a grass plot seeder, which is suitable for cultivation of fine grass varieties, a seed metering test platform was developed which has a special designed transmission mechanism and a seed cup with an adjustable ring. Several kinds of seeds can be fed by feeding mechanism in feeding cup when seeding shaft as well as distributor cone rotates one complete revolution. Seed motion and the relationship between seed outlet and seed cup were analyzed in this paper. Result of orthogonal experiment showed that the number of sweeper blades was one of the main influencing factors of the variation coefficient of seeding uniformity. When 12 sweeper blades and 9 grooves cone were used in test, the variation coefficient of the Pacesetters seeding uniformity got to the minimum value 16.46%. This research provides a reference for grass plot seeders development. Key words: agricultural machinery, mechanisms, stress analysis, plot seeder, grass cultivation doi： 10.3969/j.issn.1002-6819.2012.z2.013 Document code: A Article ID: 1002-6819(2012)-Supp.2-0072-06 CLC number: S223.2+6 0.Introduction It is important to conduct comparable tests in experimental plots with breeding, species, nutritional value and production research for grass resource and animal husbandry 1. Therefore, plot seeder plays a key role for the research and rangeland development. The design requirements of grass plot seeder are similar with conventional plot seeder, which need to feed a uniform amount of seed over the length of aplot and seed metering must be cleaned between contiguous plots because several species and mixtures may be in the same experiment. Numerous plot seeders had been developed for agronomic trials of seeding before it was applied to seeding rangeland. During 1958 to 1960, Egil yjord designed and improved a 4-row, a 6-row and a 10-row plot seeders, respectively. In 1970s, yjord plot seeders were exported from Norway to 57 countries 2. Harold G. Marshall designed a plot drill with a multiple outlet cone which is provided with multiple straight grooves 3. Most of the plot drills are unsuitable for use in rangeland trials because they cannot seed chaffy grass seed or they cannot be used in rangeland seedbeds. In 1978, Kenneth P Vogel developed an experimental plot drill by mounting a cone seeder and a spinner on a modified rangeland drill and seeded 14 species of grass. Kenneth P Vogel found that some small seeds would cause erratic feeding and incomplete cleaning of the cone, but both problems can be solved by dumping fine vermiculite into the cone before the seed is added 6. R E Barker developed an equipment which is adaptable for variety trials for small grains, grasses and legumes 3,7. In China, the research and application of plot operation machine have a great development in last several decades, but they are still backward in comparison with that of advanced countries in the world, and the plot seeder for grass breeding has not been reported 8-10. The essential element of a plot seeder is seed metering, which is composed of the cone which rotates one complete revolution when the planter moves over a plot, and seed cup centered above the cone apex. Seeds are poured into the cup by feeding mechanism and then dumped into the cone by rising the cup. Traditionally, the seed cup can be raised by hand or by using an electromagnetic lifting device10-12. And the problem of erratic feeding and incomplete cleaning can be solved by adding granular mixture but the mixture may exceed the capacity of the cone. For solving the problems mentioned above, a grass plot seeder was designed and a seed metering test-bed was fabricated based on study of domestic and foreign research. 1.Structure and principle The seed metering designed in this paper includes seed feeding mechanism, transmission mechanism and seeding mechanism (Fig.1). The seeds in seeding base plate will be pushed by sweeper blades(not shown in Fig.1) and pour into seed outlet tube when seeding shaft as well as distributor cone rotates one complete revolution. There are 18 feeding cups in feeding mechanism. All the feeding cups are connected with a feeding shaft, which is driven by a gear which meshes once with middle shaft when it rotates one complete revolution. And the feeding cups in the feeding mechanism tray will move forward 20 along circle and then be halted by a location device. Seeds in the feeding cup above the seed cup will dump on the cone. (Chinese patent number: 201120192091.5). The clearance between distributor cone and seed cup which has something to do with seed size can be adjusted by adjustable ring beforehand. 1.Drive shaft 2.Seed outlet tube 3.Seeding base plate 4.Distributor cone 5.Seeding grooves6.Adjustable ring 7.Seed cup 8.Feeding cup 9.Feeding mechanism tray10.Feeding shaft11.Middle shaft 12.Seeding shaft Fig.1 Structure diagram of seed metering 2 Analysis and calculation of seeding process 2.1Analysis of motion in seed cup When seeds are poured into seed cup, it is hoped that most part of the seeds can drop to the area around apex of the distributor cone, so that seeding uniformity could be improved. Suppose that only gravity force acts on each seed with air resistance neglected, and then motion track of the seed will be parabola (Fig.2). Taking the initial point of the parabola as the origin of the system coordinates, and the horizontal speed of seed is at the positive direction of x axis. Note: is the angular velocity of distributor cone, rad/s; x, y are coordinates of the seed; x is the distance between initial point of motion and edge of the seed cup, m; D is the opening diameter of the seed cup, m; d is the diameter of seed cup,m; h is the vertical distance between initial point of motion and the plane of lower edge of the conical inside wall;is base angle of the conical inside wall; L is the vertical distance between seed cup opening and apex of the distributor cone, m; s is the clearance between distributor cone and seed cup, m. Fig.2 Part sectioned view of seed motion If the seed can drop to the area of the distributor cone apex at time t, its coordinates x and y will be written as Where, X is x coordinate of the seed, m. Y is y coordinate of the seed, m. V is original horizontal speed of the seed, which equals to linear velocity of the feeding cup, m/s. D is the opening diameter of the seed cup, m. x is the distance between initial point of motion and edge of the seed cup, m. g is acceleration of gravity, g/s2. L is the vertical distance between seed cup opening and apex of the distributor cone, m. From the Formula (1), it is obtained that Substituting formula (3) into formula (2), the L is followed as Formula (4)indicates the relationship between L and D, V and x. To improve the seeding uniformity, the seeds also should not collide with the conical inside wall of the seed cup. When the seeds drop down to the planeof lower edge of the conical inside wall, Y=h, t can be calculated from Formula (2) and is followed as To avoid colliding with the conical inside wall of the seed cup, the displacement of the seed should be followed as Substituting Formula (1) and (5) into Formula (6) , the V is followed as Formula(4) and (7) are design requirements that seeds can drop to the area around apex of the distributor cone, which provides a design reference for feeding mechanism and seed cup. 2.2 Relationship between rotating speed of cone and seed outlet The dimensions of distributor cone as well as the dimensions of seed outlet on the seeding base platehave to satisfy certain condition because the cone and seeding base plate must be completely cleaned after one seeding revolution. Suppose that the seeds rotational radius in the seeding base plate is r(m), the angular velocity of distributor cone is (rad/s). The seed, which only gravity force acts on, is pushed by sweeper blade and falls into seed outlet (Fig.3). According to Formula (2), the time of the seed falling into seed outlet is followed as And horizontal displacement of the seed must be less than sectional dimension of the seed outlet, that is The maximum speed of the seed pushed by sweeper blade is v = r , and the angular velocity of distributor cone is followed as Where, d is diameter of the seed, m. A is sectional dimension of the seed outlet, m. v is the maximum speed of the seed, m/s. In order to avoid missing seeding and the seed being stuck by blade and seed outlet, distributor cone and seed outlet should be designed according to Formula (8). In fact, grass plot breeding needs to implement sowing in strip, therefore, a certain amount of seeds will drop to seed outlet simultaneously. Therefore, the seed outlet has to design wider than theoretical value in sectional dimension. 2.3 Design of feeding mechanism and rotating speed of cone The Plot Sowing Rate (sowing rate in a plot, PSR briefly) has to be figured out because the amount of the seed which would be seeded in one plot determines volume of a feeding cup(Table1). Suppose that unit of PSR is gram, and the length of a plot is 10 m, unify all units and it is computed by Where, Q is sowing rate, kg/hm2; B is row spacing, m;S is the length of a plot, m; Taking tall fescue for example, the its sowing rate is 22.5-37.5 kg/hm2, row spacing is 0.3 m, and the maximum PSR of tall fescue is 11.25 g. According to the maximum volumes of PSR, it is found that 12 g Chinese leymus has the largest volume, which can be calculated for design reference. The design volume is 5.55103 mm3, slightly larger than that of 12 g Chinese leymus. Suppose that the shape of the feed cup chamber is cylinder and the diameter of feed cup df is 40 mm, then the height of feed cup is approximately 45 mm. Let R be the radius of gyration of feed cup, and R=120 mm. It can be obtained that the relationship between df, R and the number of feed cup n is followed as From Eq. (10), the maximum number of feed cup can be obtained, n=18. In practical seeding, the length of a plot Lp is supposed to be 10 m. And Jiangsu 150 tractor is used with first gear speed u=2.09 km/h =0.581 m/s. According to the agronomic requirement of plot seeding, the distributor cone has to rotate one complete revolution, when seeder works over the length of a plot. The working time in one plot t which equals to the time of one circle rotation of distributor cone is followed as Then the rotation speed of distributor cone is computed 3、 Experiment and analysis 3.1 Materials and equipment 3 kinds of forage seeds have been used in the test,including tall fescue (TF), perennial ryegrass (PR), pacesetter (Pac). The characteristics of the seeds have been examined and listed in Tab.213-14. And the average value of PSR was used as Actual Sowing Rate (actual sowing amount in a feeding cup, ASR briefly). In table 2, the sliding friction angles were tested by putting seeds on an inclined PVC plastic plane, which was made of the same material with distributor cone. The instruments used in experiment included electronic balance, vernier caliper, etc. A plot seed metering test platform(fig.1) was developed, which can be modified by changing the number of sweeper blades and distributor cone. 3.2 Experimental factors and methods The influencing factors on seeding uniformity are the grooves on distributor cone, along which seeds fall down to the seeding base plate, and species of grass seeds, which have different shapes and friction characteristics. The number of grooves, sweeper blades and three kinds of seeds were chosen as experimental factors to conduct experiments. Pre-experiments showed that diameter of seed cup d should not be too small for some seeds which are inclined to bridge in seed cup, so a seed cup which diameter d is 25 mm was used in the test, and the gap s between seed cup and distributor cone is 5 mm. The influence factors and levels of test are shown in Table 3. The factor B is the number of sweeper blades used in grass seeder, which divided seeding base plat into 36, 18, 12 areas, respectively. 3 kinds of distributor cone were designed, and two of them have 18, 9 grooves, respectively. The other one is no grooves on cones surface. The base diameter of all cones is 104 mm and base angle of all cones is 45, which is greater than the maximum value of sliding friction angle. 3.3 Experiment results and analysis In the experiment, L9(34) the orthogonal table was used and the results are listed in table 4. It consists of 9 treatments with 3 replications and response variable is variation coefficient of seeding uniformity (cv), which will be calculated after each replication. The variation coefficient of seeding uniformity was calculated by measuring quality of seeds in each areas divided by sweeper blades. The equation of variation coefficient of seeding uniformity cv is followed as Where, n equals to the number of sweeper blades, x is average value of xi. From Table 4 we can know that the number of sweeper blades is main factors of influence cv, which will decrease with the reduction of the number of sweeper blades. The length of gaps will increase with the reduction of the number of blades. However, since the sowing rate is specified, the spacing rate in one plot sowing will also increase if the length of gaps was too large. The number of grooves has little effect on cv, probably because it is very short time that seeds slide from the top of the cone to the bottom. The side walls of straight grooves have little contact with seeds. Therefore, the horizontal displacement of seeds along he surface of cone is approximately equal to zero. 4.Conclusions 1) This research developed a seed metering test platform of grass plot seeder. It has a transmission mechanism using a batch-type mashing mechanism, which can drive feeding mechanism by meshing once when the middle shaft rotates one complete revolution. 2) An adjustable ring on seed cup was designed, which can change the gap between seed cup and distributor cone. 3) Seed motion in seed cup was analyzed and relationship between velocity of seeds and dimension of seed outlet was researched. And quantitative relationships between seeds, rotating speed of cone and seed outlet were established. 4) By conducting experiment, it is found that the number of sweeper blades is the main influencing factors of the variation coefficient of seeding uniformity, and the range value is 16.58. When 12 sweeper blades, 9 grooves cone and Pacesetter were used in test, the variation coefficient of seeding uniformity achieves the minimum value 16.46%. The species of seeds and the number of grooves have little and the least influence on the variation coefficient of seeding uniformity, respectively. Based on this research, the details of seed motion in seed metering can be further analyzed under the practical condition. Further research and manufacture prototypes can be conducted for grass plot seeding work. References 1Qu Yan, Zhang Shumin. Design and research of feedingmechanism of plot seederJ. Modern AgriculturalSciences and Technology, 2011(10): 241 242. 1yjord.yjord Plot SeedersEB/OL. www.ffe.slu.se/IAMFE/Info/Oyjord_plot_seeders.pdf/ 2012-04-29. 1Liu Shuguang, Shang Shuqi, Yang Ranbing, et al.Analysis of Plot Seeder DevelopmentJ. Journal ofAgricultural Mechanization Research, 2011(3):237-241. 1Shang Shuqi, Yang Ranbing, Yin Yuanyuan, et al. Currentsituation and development trend of mechanization of fieldexperimentsJ. 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Journal of Agricultural Mechanization Research, 2004(4): 14 16. 1Liu Shuguang, Shang Shuqi, Yang Ranbing, et al. Test and optimization of parameters for the storing device of plot seederJ. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE),2010, 26(9): 101 108. 1Jiang Feng, Chen Haitao, Wang Yecheng. Design of insert-metering device for subdistrict breeding seederJ. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2010,26(Supp.1): 9 12. 1Liu Shuguang, Shang Shuqi, Yang Ranbing et al. Test on performance of seed-filling device of plot seederJ.Journal of China Agricultural University, 2011, 16(3):156 163. 1GB/T2930.1-2930.11-2001, Rules for forage seed testingS. 1GB/T25421-2010, No-tillage seeding drill for the grassS. 牧草小区播种机排种器的设计及试验 杨 松，张淑敏，易金涛，翁 强 摘要 ：为了研制适用于优良牧草栽培的牧草小区播种机，设计制作了牧草小区播种机排种器试验台。该试验台有一专门设计 的转动机构和一个可调节的排种环。送种机构中的多个送种杯中的种子可以依次喂入排种系统，且分种锥旋转一周时，一个送种杯内的种子恰好播完。对种子在存种筒内的受力、运动过程和排种口尺寸的关系做了分