Research Design And Experimental Study On Portable Electric Tea Plucking Machine

Tea plucking is one of the important links in ensuring the quality and efficiency during the production of tea.Because of the large-scale tea-picking machinery is not applicable,the difficulty of picking tea pickers and the high labor costs in hilly areas,It is of great practical significance to carry out the design and experimental research of the key components of portable electric tea-picking equipment.In this thesis,the tea-tree shoots of Mao-lv were studied and their growth and culm mechanical parameters were measured.The overall structure and key components of the portable electric teaplucking device were designed.The parameters which affect the plucking performance was analyzed and optimized based on the double-action knife cutting chart.Last the bench tests for plucking performance were performed.The main research contents and results are as follows:(1)Parameters Analysis and Mechanical Properties studied of Tea Tree Canopy ShootsThe Mao-lv tea tree was used as a test object,and the parameters of shoots with three leaves was measured and counted,The results showed that the gradient of the shoots ranged from 0.8 to 30.1°,the average tilt angle was 9.2°,the length was 66.1 to 113.1 mm,the average length was 86.6 mm,and the diameter of the fourth stem was 2.0 ~3.2 mm,the average diameter was 2.5 mm;The height range of remaining stubble is 15.6~55.8 mm after plucking the shoot with three leaves,and the average stubble height is 34.7mm.The compressive and shearing mechanical properties of the stem of the fourth section of the tea tree shoot were tested by a texture analyzer.The corresponding force-displacement curve was obtained and the modulus is 31.81 MPa,the compression modulus is 10.12 MPa,and the shear modulus is 9.19 MPa.(2)Design of the overall structure and key parts of the tea plucking machine.The structure of the portable electric tea plucking machine is designed,including the cutter,the leaf blade and the impeller.The style of the cutter is reciprocating double knife cutter,the blade Angle is 40°,the blade width is 10 mm,the width of the front axle is 2 mm and the blade height is 1.5 mm,The blade cutting Angle is between 0° and20°,The deciduous tooth width of the leaf blade was 10 mm,the spacing of the deciduous teeth was 20 mm,the length of the deciduous teeth was 60 mm and the single sweep blade height of the impeller is 120 mm,through the cut test determined.The structure of the blade is determined by the comparison test.(3)Parameters optimization and cutting simulation analysis of Double-action knife reciprocating cutterThe cutter motion model is established,The cutter path under different structural parameters and motion parameters was obtained,and the cutting graph of the Doubleaction knife reciprocating cutter was drawn.A three-factor and three-level cutting test was designed.Based on Design-Expert8.0.6 software,the effects of blade height,blade pitch and cutting speed ratio on the primary cutting zone,missed cutting zone and recut zone in the cutting chart were analyzed.The response surface method was used to optimize the cutter parameters,and the optimal parameter combination was obtained with a blade pitch of 20 mm,a blade height of 19 mm and a cutting speed ratio of 1.05.At the same time,the finite element model of single stalk cutting was set up by ANSYS_LS_DYNA module,and the cutting process of stem was simulated and analyzed.The simulation showed that the cutter parameters and motion parameters were reasonable.(4)Tea plucking performance testIn order to explore the effect of different travel speed,cutting speed and plucking angle at a certain cutting speed ratio to the leakage rate and the complete rate of shoots and the reasonable working parameters,The bench test was carried out.The results show that when the cutting speed ratio is 1.05 and the plucking angle is 0°,the plucking leakage ration are all less than 3% at different travel speeds and cutting speeds,is similar to the missing rate 2.54% after the parameters of cutter was optimized.The completeness of plucking tea was higher than 80%,indicating that the plucking effect was good.At the same time,with the plucking angle of 0° as a reference,the influence of different plucking angles on the plucking effect was analyzed,and it was found that increasing the plucking angle resulted in an increase in the rate of missed cuts and the reduction of the leaf integrity rate.The cutting speed is adjusted to-3° when the traveling speed is large,can effectively reduce the leakage cutting rate and shoot integrity.This dissertation designs and trials a portable electric tea plucking device,optimizes the working parameters of the cutter based on the cutting chart,and the plucking performance test shows that the tea has high integrity and low cutting rate with the device.It is suitable for tea plucking in hilly regions after further improvement.