Analysis Of Flue-cured Tobacco Transplanting Process And Optimization Of Machine Tool Structure

Hole-making for transplanting seedling is an important link in the production of tobacco,which has the characteristics of high labor intensity and high operation requirements.The tobacco transplanting-hole provide a microclimatic environment for the growth of tobacco seedlings after field transplantation.The quality of transplanting-hole is directly related to the revive seedling growth,field growth,quality and yield of tobacco after transplantation.At present,the production of transplanted nests for flue-cured tobacco still adopts the operation mode of manual+general agricultural tools,which takes time and labor,has great labor intensity,low efficiency and poor consistency.Especially with the rising cost of labor and the prominence of labor shortage year by year,the research and development of hole-making machine for transplanting tobacco seedling has become an urgent problem to be solved in order to save labor,reduce cost,improve quality and increase efficiency in flue-cured tobacco production.The Dawo hole-making machine developed by our research group has basically fulfilled the agronomic requirements of transplantating tobacco,but there are still some problems such as low qualified rate of hole-making,high power consumption and large vibration.Therefore,in-depth analysis of tobacco transplanting hole-forming mechanism,power consumption and vibration,and Research on ways to improve the comprehensive performance of the hole-making machine are the core issues facing further research and development and promotion of the hole-making machine.In this paper,based on the analysis of the theory of tobacco seedling transplanting hole-mnaking,the design of key components of hole-making machine is completed,and the simulation analysis and optimization of key components of hole-making process are carried out by using the discrete element method and the finite element method combined with the current technical characteristics,current situation,development trend and agronomic requirements of nesting and hole-making for transplanting tobacco seedling.Finally,field experiments were carried out on the developed prototype,and the optimal combination of working parameters for hole-making operation was obtained.The research contents of this paper mainly include the following aspects:(1)Through the study of soil particle and soil flow law,the numerical values of the spiral angle and critical speed of the acupoint are obtained,which provides theoretical parameters for the design of the spiral acupoint.The design of the key components mainly consists of two parts:the transmission part and the cavitation device.The transmission part is composed of a flexible shaft,a joystick and a reducer.The cavitation device consists of a protective cover and a spiral acupoint.Finally,the power of the engine is calculated.(2)Based on the discrete element method,the simulation and parameter optimization of caving process are completed.The optimal combination of nesting parameters was obtained by discrete element simulation analysis under different speeds,guides,residence time at the bottom of the nest and soil moisture content.Through the establishment of soil trough models with different particle sizes,the soil disturbance analysis of the process of spiral hole-making was carried out,and the soil disturbance and the change of the movement speed of soil particles in different tillage layers were obtained.(3)Based on the finite element method,the static and dynamic analysis of spiral grooving head is completed.The maximum deformation of spiral grooving head in three directions of X,Y and Z is 0.010273 mm,0.020998 mm and 0.00022015 mm,respectively.Generally,the deformation is small,which verifies the feasibility of the design.The harmonic response analysis and topology optimization of the joystick are carried out,and the three frequencies at which the joystick is prone to resonance are obtained.The working frequency should avoid these three frequencies.Using the Shape Optimization module in Ansys to lightly design the joystick,the topology optimization scheme of the joystick is obtained under the condition that the stiffness and strength of the joystick are not changed much.(4)According to the design parameters,the test prototype is used to carry out the single factor and multi-factor orthogonal test to obtain the best parameter combination for hole machine.All of the parameters are optimization by using the Box-Behnken response surface in the Design-Expert software.The results show that the conclusion of software optimization is very close to the orthogonal test results,which further verifies the reliability of the orthogonal test results.