Design And Experiment Of Ridge Lawn Mower In Apple Orchard

The apple cultivation model is developing rapidly to the modern short stock dense planting model in China.Grass growing in the garden is an important management technique to improve the soil environment of the apple orchard.For the management of the grass in the park,the row mower is generally used for mechanized cutting and returning to the field.However,for the orchard with ridged cultivation,the grass on both sides of the ridge of the fruit tree ground cloth can only be manually cut or sprayed for weeding due to terrain restrictions.Aiming at the difficulty of mechanized cutting of weeds on the ridges on both sides of the fruit tree ground cloth,the orchard ridge grass cutting device and the performance of grass arranging were studied,in order to realize the simultaneous mowing of the fruit trees and the ridge surface at the same time.Field investigated on the cultivation characteristics and ridge topography data of short anvils and dense planting apple orchards,combined with the research status of orchard lawn mowers at home and abroad,determined the shape parameters of orchard ridge lawn mowers,designed and calculated the working parameter range of each component,used AIP(Autodesk Inventor Professional)3D design software to establishe a digital prototype of the lawn mower,which laid a model foundation for the parameter optimization of the lawn mower.In order to determine the best working parameters of the ridge surface cutting device,a three-dimensional solid model of the ridge surface cutting cutter head was established and the optimization simulation test of the influence of forward speed,cutter head speed,number of blades and blade line length on the recut rate and missed cut rate were carried out.The dynamic analysis software obtained the blade movement trajectory and calculated the area of re-cutting and missing cutting,taking the forward speed,cutter head speed,number of blades and the length of the edge line as the influencing factors,taking the re-cutting rate and the missing cutting rate as corresponding indicators,and using the response surface.Analytical method was used to perform four-factor three-level virtual orthogonal test on the model.The results showed that the recut rate and missed cut rate were the lowest when the forward speed was 2 m/s,the cutter head speed was 2700 r/min,the number of blades was 2,and the cutting edge length was 95 mm.The minimum recut rate was 1.3%,and the minimum missed cut rate was 2.96%.Based on this,the cutting cutter head was optimized and improved,and the gearbox transmission ratio was determined to be 1:5.Aiming at the problem that it was difficult to ensure the consistency of the cutting height of the ridge surface,the vibration characteristics of the ridge surface cutting device were analyzed.Through the use of dynamics software to carry out basic modal analysis and vibration dynamics analysis of the ridge surface cutting device,it was concluded that the first-order modal frequency of the cutting device was 125.01 Hz,the corresponding limit speed was 7500.6 r/min,and the design speed of the orchard ridge surface mower was 2700 r/min,which was much lower than its dangerous speed.Through the random vibration displacement response analysis of the cutting device,the main vibration characteristics of the cutting device were obtained.At the same time,the main vibration transmission path of the cutting device in the working state was obtained through the acceleration load analysis.Through the harmonic response analysis of the cutting device,it was founded that the radial amplitude of the top of the flinger reached the maximum at 180 Hz,the dynamic stiffness of the flinger decreases,and the flinger was prone to fracture;the spline sleeve was connected to the cutter head at 250 Hz.The welding seam at the location was prone to cracks,and the flailing knife and cutter head were optimized and improved based on this,which provided data basis and new ideas for the research of further vibration reduction measures for the cutting device.In order to analyze the effect of the high-speed airflow on the specific flow direction of the weeds after cutting,the flow field analysis software was used to simulate the wind speed of the lawn mower.The data showed that the flow pattern of the main plate airflow was helpful to the cutting.The grass cuttings were discharged through the middle of the cutter head,and the air flow inside the side plate could achieve the effect of double-port grass discharge.The speed cloud diagram showed that the bending on both sides of the lawn mower had a higher reverse speed,which could effectively avoid grass gathering inside the lawn mower.Through the analysis of the pressure cloud diagram of the lawn mower,its own geometric contour of the wall had a certain influence on the pressure distribution of the internal flow field.By optimizing the contour of the wall,the symmetry and balance of the air flow could be ensured to a certain extent,and the adverse effect of aerodynamic characteristics on the working condition of mower could be eliminated.Field tests were conducted on orchard mowers,and the data statistics and analysis of each verification index after the test showed that the recut rate,missed cut rate,stubble height stability coefficient and grass cutting rate all meet the test standards of rotary lawn mowers.It conformed to the design requirements of orchard lawn mowers and met the needs of returning the grass to the field between the rows and ridges of the fruit trees at the same time.