Research On Cavitation Drill Bit For Cellar Transplantation

The transplanting of tobacco seedlings is an important part of flue-cured tobacco production.At present,there are transplanting methods of tobacco seedlings,which mainly include conventional transplanting,above-membrane smoke transplanting,under-membrane smoke transplanting of seedlings,conventional well pit transplanting and under-membrane smoke transplanting.Compared with the conventional transplanting,the well cellar transplanting technology of flue-cured tobacco seedlings is still short in seedling stage,and the growth of tobacco seedlings is rapid,which is conducive to the early growth of tobacco seedlings.The well cellar quality has a great impact on the early growth and development of tobacco seedlings,thus affecting the yield and quality of tobacco leaves.At present,there are two kinds of bits in the market: gyro bit and spiral blade bit.The hole forming mechanism of the gyroscopic bit is compact forming,the inner wall of the pit is compact,the inner wall is smooth,and the pit is stable,but the pit is not conducive to the growth and development of the early stage of the smoke seedling.The hole forming mechanism of the spiral blade bit is cutting forming,the inner wall of the pit is compact,the inner wall is rough,which is conducive to the growth and development of the early stage of the smoke seedling,but in the process of the hole forming The stability of well cellar is poor.In Guizhou area,the hole forming bit used in the well cellar transplanting is a gyroscopic bit,which is not easy to collapse,has high hole forming efficiency and is easy to operate.In Baise area,Guangxi Province,two blades are symmetrically distributed in the center,which is light in weight and material saving.However,the problems of smooth inner wall and high compactness exist in the pits made by the above drill bits,which are not conducive to the growth and development of the early stage of the tobacco seedling.(1)Mechanism analysis of drill hole formation.Field experiments were carried out on the existing drill bits in the market,and the cavitation effect was compared and the cavitation mechanism was studied.The advantages and disadvantages of various types of drill bits are analyzed to provide theoretical support for the design of drill bit structure.It is concluded that the cavitation mechanism of gyro bit is compaction forming and that of spiral vane bit is cutting forming.(2)Simulation analysis of drill hole formation.Solid Works was used to build a 3d model of the drill bit,and EDEM software was introduced to conduct cave-forming simulation to analyze the variation trend of the influence of the structural parameters of the drill bit on the bit force.The simulation results show that the bit tile blade structure should adopt the reverse type,the height of the spiral blade should be 120 mm,and the leading path of the spiral blade should be 200 mm.(3)Optimized design of drill bit structure.Through the combination of theory and field experiment,the type of drill tip,positive and negative direction of tile blade,leading path and height of spiral blade were optimized,and the optimum structural parameters of drill were obtained under the condition of satisfying agronomic requirements.Through optimization,it is obtained that the drill bit should adopt conical drill tip,reverse tile blade,the height of spiral blade is 120 mm,and the leading path of spiral blade is 200 mm.Adding bionic convex hull on the spiral blade can reduce the adhesion of soil.(4)Field test and formulation of agronomic standards.The drilling bit was machined and the hole forming experiment was carried out to analyze the hole forming effect of the bit.Based on the study of the soil environment,the best range of soil physical parameters suitable for the production of well cellar was obtained through experiments.In view of the dry soil,the quantity of water was determined through experiments to ensure the quality of cavitation.Through a series of field experiments,the agronomic standards for well pit transplanting of tobacco seedlings in baise area of guangxi were established.It is concluded that the optimal soil moisture range for drill hole formation is 30%-50%.When the moisture is lower than 20%,water needs to be added to 200 ml.The optimum soil hardness range for drill hole formation is 90-150 n /cm2.In order to prevent the stopping and shaft winding of the bit in the process of cavitation,the knap-back gasoline engine needs a reducer with a ratio of 2:1.