Design Analysis And Experimental Study On Cutting Device Of Fruit Tree Seedling Stubble Machine

With the wide spread of dwarf planting model in fruit trees,the demand for dwarf seedlings increases.Before grafting,the seedlings of fruit trees need to be treated with stumping,and manual use of fruit tree shears for stumping operation will increase labor intensity and lower operating efficiency.The structure and parameters of cutting device are the key factors to ensure the quality of stumping and the technical difficulties in the design of stubble machine.The shearing test of apple rootstock was carried out,and the shearing mechanical properties of apple rootstock were obtained.The yield point and the breaking point of the rootstock were obtained by outputting the rootstock force curve,and the shearing power consumption of the output mechanical characteristic curve was calculated.Cutting device design provides a reference basis.Through the investigation and review of relevant literatures in the nursery base,the structure scheme of the tractor front suspension type stubble machine was determined,and the power transmission system from the tractor rear output shaft to the front stubble machine was designed by using AIP three-dimensional modeling software.The circular saw is used as the cutting part of the flat-cutting machine.The kinematics equation of the cutting part is studied.The motion force of the circular saw is analyzed.The power of the disc cutting process is analyzed by the classical resistance work and the cutting force.The rootstock cutting dynamics simulation model was established by ANSYS LS-DYNA software.The three-factor and three-level virtual orthogonal simulation test table was designed for the sawing process using Design Expert dynamic response software.The sawing teeth number,feed speed and sawing disc rotation speed are three factors,and the dynamic response surface is selected to have the disc sawtooth number of 100,the rotation speed is 4200r/min,and the feed speed is 1km/h.Applying the optimal parameters to the prototype design,the modal analysis of the circular saw of the cutting part is carried out,and the static frequency and the local frequency mode of the cutting part of the circular saw with the rotational speed of 4200r/min are obtained,and the simplified circular sawtooth is adopted.Motion analysis of the lateral vibration of the circular saw.When the cutting speed is 4200r/min,the first-order critical speed is 4558.26r/min,and the rotation speed is within a safe and reasonable interval.The detailed structure and geometric parameters of the cutting device were determined based on design calculations and simulation results.A sample prototype of the stubble machine model was established,and the apple seedling stubble test method and the stump quality evaluation index were formulated.The stubble test was carried out at the seedling base.The results showed that the stubble machine was divided into a stepped fracture and a tearing fracture.The stepped fracture had no effect on the rootstock,but the tearing fracture affected the quality of the rootstock.Field trials have shown that this seedling stubble machine meets the agronomic requirements of fruit trees and seedlings,and the pass rate after stumping is higher than 95%.