Analysis And Optimization Of Vibration Cutting Resistance Of Curved Shovel Of Tree Spades

Tree transplant technology can greatly accelerate urban greening progress and complete urban garden planning.At present,most of the tree transplanting work in China uses manual transplantation,which is not only inefficient and labor intensive,but also can not guarantee the survival rate of trees.Designing and manufacturing high-performance tree transplanting machinery is of great significance.The U-shaped shovel tree spades has simple structure,convenient operation and can move trees in a small space,which is suitable for the construction of urban gardens in China.The traditional U-shovel tree spades is limited in structure and can only be used to transplant small-diameter trees.The new vibrating U-shovel tree spades uses the mechanism of vibration cutting to reduce the resistance of the cutting process,and can realize the transplantation of large and medium-sized trees.This paper mainly analyzes the mechanism of vibration cutting and cutting resistance of the curved shovel of the tree spades,numerically simulates the working process of the tree spades,and applies the orthogonal test method and regression analysis to determine the best working parameters of the tree spades.The main work and content of the thesis includes the following aspects:(1)The shear strength characteristics of the soil is analyzed and the three ways in which the soil reaches the limit equilibrium state are discussed.The reasons for the decrease of shear strength of soils with different properties under vibration load are discussed.This paper introduces the working principle and main technical parameters of the vibrating U-shovel tree spades walking system,cutting system,boom system and hydraulic system.The stability of the tree spades during work is checked.Determining the natural frequency of the curved shovel by modal analysis.Providing a theoretical basis for the determination of the tree spades working parameters.(2)The equation of motion trajectory at the center of the curved shovel is established,and the relationship between the motion state of the curved shovel in the soil and its amplitude,frequency,cutting speed is discussed.The relationship between the cutting resistance and the cutting speed,frequency of the curved shovel under vibration conditions is analyzed.The factors affecting the cutting resistance under non-vibration conditions are analyzed,and the cutting resistance of the cutting soil ball radius of 0.6 m and 0.4 m was calculated by the empirical formula.(3)Using ANSYS/LS-DYAN,the finite element analysis of the cutting process of the curved shovel is carried out to see the shovel stress,soil stress and cutting resistance during the cutting process.The stress changes and cutting resistance changes under vibration and nonvibration conditions are compared.Vibration cutting helps to improve the bending tool stress,improve cutting soil ability and reduce cutting resistance.(4)The cutting resistance under the different working parameters is calculate.The experimental data is processed by orthogonal test method to determine the order of the working parameters influence on cutting resistance: vibration amplitude,vibration frequency and cutting speed.This paper finds the combination of the optimal working parameters of the tree spades and compares it with the original working parameters.The optimal working parameters can reduce the cutting resistance by 32.7%.The test results are subjected to regression analysis using Design-Expert to fit the regression equation between amplitude,frequency,cutting speed and cutting resistance.