Design Of Spreading Soil Device For Factor Rice Seedling-nursery And Research On The Measurement Of Bed Soil Thickness

The technology of Factory Seedling-nursery is the development direction of the paddy cultivating technology in our country, to research and design the seedling-nursery device is one of the most important methods to impel the seedling-nursery technology to develop unceasingly. Factory Seedling-nursery is made up of four processes which are Soil-spread, Precision seeding, Soil-cover and Water spray. In the usually opinion, the most important process is the Precision seeding, but the process of soil-spread is also essential to the seedling-nursery. With the development of the technology of super paddy seedling-nursery, the number of the seeds in per hole is decreased and the seeding precision is enhanced, so it is much strict to the processes of Soil-spread and Soil-cover, the quality of seedling will be reduced if the thickness of soil in the tray is not uniformity.Combined with the project of"Research on the Super Rice's Lower Cost and Precision Seedling-nursery Technology and Equipment"(NO.2006BAD28B01) which is supported by the"11th Five-Year Plan", and on the basis of the development condition of the technology of Factory Seedling-nursery and the structure characteristic of spreading soil device in the international and domestic countries, the thesis analyzed and pointed out the shortage of the existing spreading soil device, and putted forward a new type of spreading soil device and measuring technology of bed thickness.The theoretic analysis and the experimental test are carried out. The following is the conclusion of the thesis.1. On the basis of introducing the research condition of the soil-spread and soil-cover devices in the international and domestic countries by the numbers, and analyzing their structure characteristic and shortage in details, the purpose of the research in the thesis was putted forward: a spreading soil device which spreads and covers soil steadily is developed, the large diameter drum with V-shaped tablet as the soil-spread components of the spreading soil device is chosen.2. The sizes of the lager drum with the V-shaped tablet were confirmed, and the distribution of the V-shaped tablet on the film of the drum was also confirmed in order to ensure the spreading soil device to spread soil continuously when the drum rotates slowly. Made full use of the friction angle between soil and steel, the position of the soil box placket, the gradient of the soil-lead board was confirmed. In order to prevent the soil splashing, a block was designed. The thesis set up the mechanics model that indicates the relation between the rotate speed of the drum and productivity, the thickness of the soil in the tray, the width of the V-shaped tablet, and set up the mechanics model that indicates the relation between the volume of the soil expelled from the soil box per second and the rotate speed of the drum, the sizes of the V-shaped tablet. On the basis of the Pro/E software, the 3D siMULation model of the spreading soil device was set up.3. By means of orthogonal test, it analyzed the effects due to the changes of the parameters of V-shape tablet and the humidity of soil was analyzed when the productivity equals 500traies per hour. The results of tests show that the highest stability of spreading soil is happened when the helix obliquity of the V-shaped tablet's flank equals 40degree, the width of the V-shaped tablet equals 35millimeter and the humidity of soil equals 9%, the variety rate of the volume of expelled soil equals 4.5%, further more, there is no dust flying upwards.4. By means of orthogonal test, it analyzed the effects due to the changing of the rotate speed of the drum, the humidity of soil and the size of the soil box placket, calculated the variety rate of the thickness of the soil in the tray. The results of experiments show that when the rotate speed of the drum equals 16rph, the humidity of soil equals 9%, and the size of the soil box placket equals 3.5 millimeter; the variety rate is least, and the performance is best.The humidity range of soil be fit to the spreading soil device is lager than the traditional range which is four percents to six percents.5. Bazed on the principle of the ultrasonic distance measurement and SCM, the mearsurement of bed soil thickness is designed, the detector includes hardware and software. The hardware is composed of the signals controlling circuit, ultrasonic sending and receiving circuit, temperature collecting circuit and data displaying circuit. The software is made up of four modules which are signals controlled, temperature collecting, thickness detecting and data displaying, the programs of these modules were written out.The test results show that: the max relative error of the measurement of bed soil thickness is 29.7%. At last, the factors that course the errors are analyzed,and the methods of enhancing the precision are put forward.