| Taro is an important aquatic vegetable in China,with its soft taste,rich nutritional value and high economic benefits,and is widely planted in China.Taro harvesting is labor-intensive,complex working environment and harvesting processes,which to a certain extent restrict the industrialization and scale development of taro.In this paper,based on planting agronomy and harvesting requirements,based on the early petiole growth characteristics and mechanical properties of taro harvesting,we designed a vibration shovel digging clip-pull taro excavator,which uses a combination of digging and pulling for harvesting operations,while using vibration digging to reduce resistance and reduce congestion in order to improve the quality of taro harvesting.The study and its findings are as follows.(1)Measurement of taro petiole growth characteristics in early harvest.The growth geometry was measured in the range of 80～120 mm,80～160 mm,and 160～240 mm for the bottom,middle,and upper petiole transverse axes in the natural state,and in the aggregated state,the bottom,middle,and upper petiole transverse axes in the range of80～120 mm,80～160 mm,and 160～240 mm,respectively.In the aggregated state,the ranges of concentrated size of the transverse axes of the bottom,middle and upper petioles were 70～100 mm,55～160 mm and 70～100 mm,respectively.(2)Experimental study of mechanical properties of taro petioles in early harvest.The bending,shearing and tensile properties of petioles were tested,which showed that the bending and shearing forces gradually decreased as the petiole part rose,while the tensile force was the smallest in the middle section,with a maximum average bending force of110.99 N,a maximum average shearing force of 77.10 N and a maximum average tensile force of 217.17 N.The tensile test of petioles was conducted,which showed that at a certain clamping distance and loading speed The lower the clamping position,the greater the maximum instantaneous slip force,the easier it is to pull up the taro;pulling force test was conducted,the test showed that: at a loosening depth of 200 mm,the average pull up taro was 164.78 N,much less than the taro petiole pull off force,proposed to use a combination of pulling and pulling for harvesting.(3)vibration shovel digging clip-pulling taro excavator structure design.The machine consists of a frame,vibrating digging device,clamping and conveying device,petiole cutting device,tensioning device,walking digging depth adjustment device,etc.,in order to complete the taro digging,conveying,taro petiole separation and petiole laying functions to achieve taro digging and pulling harvesting.In the premise of following the structural layout,the transmission system was designed,the proposed input speed and timing belt pulley speed ratio of 2:1,and eccentric pulley speed ratio of 1:1,and the knife speed ratio of 2:3,estimated the equipment supporting traction power,to determine the small and medium-sized tractors are able to support the use.(4)Key components design and analysis.The design,theoretical analysis and simulation of the whole machine frame,clamping and conveying device,vibration digging device and leaf shank cutting device,optimize its structure and parameters.Static analysis of the frame was conducted,and the weakest point of the frame was found to be at the weld between the supporting square tube and the main body of the support frame of the clamping and conveying device on the fixed left side,and its structural strength met the design requirements.Modal analysis of the frame showed that resonance may occur in the second order mode,and thicker support square tube and more reinforcement at the welded area are required for processing.It was determined that the clamping and conveying device adopts flexible clamping,and the clamping part adopts synchronous belt.The relationship between clamping and conveying speed and forward speed was established,and it was determined that the synchronous pulley is 8M type and the synchronous belt is HTD8 M type.The blade structure was designed to determine the blade height of 100 mm,the blade width of 60 mm,the blade angle of 15°,the blade thickness of 5 mm,and the number of blades of 3 pieces;the eccentric wheel mechanism of the vibration excavation device was designed to determine the excavation shovel to use the plane third-order excavation shovel,and the main parameters of the excavation shovel were determined by theoretical analysis.The analysis found that the weakest point of the shovel is at the welding point of the shovel tip and the shovel lug,the maximum deformation is 0.93 mm,and the maximum stress is 77.46 MPa,which meets the material strength requirements.(5)Vibration excavation component performance analysis based on EDEM and RecurDyn coupling simulation.In order to verify the excavation performance of the designed excavation part,the excavation performance of different shovel surface steps was compared and analyzed,and it was verified that the soil breaking ability of the third-stage excavation shovel was better than that of the first-stage and second-stage excavation shovel,and its average travel resistance was the smallest and 588.25 N.The excavation performance of the fixed and vibratory excavation shovel was compared and analyzed,and it was found that the average travel resistance of the vibratory type was reduced by 22.8% compared with that of the fixed excavation shovel.The number of bonding bond breakage increased by 105%,and its digging performance was stronger.In order to determine the optimal combination of operating parameters of the machine,simulation tests were conducted on the vibratory digging mechanism,and single-factor tests were conducted to investigate the influence law of the influencing factors on the digging performance,and the entry angle was set at 20°,25° and 30°,the forward speed was set at 0.6 m/s,0.8 m/s and 1 m/s,the eccentricity was set at 4 mm,5 mm and 6 mm,and the vibration frequency was set at 9 The orthogonal test was designed using Design-Expert 10.0.7 software,and the orthogonal test results showed that the main order of influence on travel resistance was forward speed > angle of entry > eccentric distance > frequency,and the interaction between angle of entry and eccentric distance had a significant influence on travel resistance.The regression equation was established and the parameters were optimized to obtain the best combination of operating parameters:angle of entry of 20°,forward speed of 0.6 m/s,eccentricity of 6 mm,and vibration frequency of 12 Hz.(6)Taro harvester performance test.The test results showed that the stalk length was consistent,and the taro had 96.93% of bright taro,2.67% of wounded taro and 2.86% of broken skin,in accordance with the national standards,which verified the reasonableness of the machine design. |
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