| Sweet potato is an important agricultural product in China,and its planting area is more than 5 million hm~2,so sweet potato harvester has a big market demand.However,the current sweet potato harvester still has problems in harvesting operation,such as low bright potato rate,high potato injury rate,high resistance when moving forward,insufficient safety performance and stability of the rack.Aiming at these problems,the vibration sweet potato harvester was designed and tested,to solve the above problems.The main contents of this paper are as follows:(1)By referring to the data,combining the agronomic pattern and harvest requirements of sweet potato in China,the whole machine design scheme of sweet potato harvester was determined.The main components of the harvester include:digging shovel,rack,components of vibrating screen soil,and designed the sprocket drive system.(2)The force and simulation analysis of digging shovel and frame are carried out.In order to ensure the integrity of sweet potato and reduce the forward resistance during harvest,the Angle of the shovel blade was determined to be 42°and the excavation Angle of the shovel was determined to be 25°.According to the width of sweet potato ridge,the width of digging shovel was determined to be 900 mm;The statics analysis of excavation shovel is carried out by ANSYS software,which ensures that it will not fracture in working.The statics analysis of the frame of harvester is carried out,which verifies the safety and reliability of the frame in normal operation;Through modal analysis,it is concluded that the fixed vibration frequency of the frame is not in the same range as the external excitation frequency,so there will be no resonance phenomenon.The structure design of the frame will not cause additional damage to sweet potato during harvest.(3)The main components of vibrating screen soil unit are introduced.The main components include:drive shaft,special-shaped vibration wheel,screen.The structure of the drive shaft is introduced.The function of the special-shaped vibration wheel is explained,and the number of blades of the vibration wheel is determined as 3 by calculating and analyzing.According to the volume size of sweet potato and the effect of soil screening,the clearance of round steel bar on the screen was determined to be 55mm;Through the force analysis,the linear speed of the screen conveyor belt should be greater than the forward speed of the tractor,Finally,the motion of sweet potato on the screen was kinematically analyzed,and the inclination Angle of the screen was determined to be 20°,and the linear speed of the conveyor belt was 1.5 m/s.(4)The field experiment of vibrating sweet potato harvester was carried out.After completing the trial production of the vibrating sweet potato harvester,a preliminary test was carried out,and the test results showed that the rate of bright potato was 100%,the rate of damaged potato was 2.9%,and the rate of broken potato was 1.81%,which met the industry standard.In parameter optimization test design,the forward speed of the harvester,the linear speed of the screen conveyor belt and the amplitude of the screen were taken as factor parameters,and the rate of potato injury and net potato rate were taken as evaluation indexes to carry out the test,through the analysis of the results of the experiment by design-Expert software,the influence of each factor on the harvest index was obtained.The optimal parameter combination obtained is:the forward speed is 1.02 m/s,the belt speed of the screen is 1.48 m/s,the vibration amplitude is 32.9 mm.Test according to the optimal parameters,the results showed that the rate of broken potato was 1.60%and The net tuber rate was 96.1%. |
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