| Pepper and tomato are one of the main vegetable crops in China.At present,the cultivation of pepper and tomato has changed from traditional manual transplanting to mechanized transplanting,which can effectively reduce labor intensity and labor cost.However,there are some problems in mechanized transplanting,such as poor soil penetration.According to the agronomic requirements of transplanting pepper and tomato seedlings in pot,two kinds of transplanting hanging cups were innovatively designed and manufactured:spade-shaped hanging cup and fork-shaped hanging cup.The main tasks completed are as follows:(1)The technical requirements of the hanging cup were analyzed.According to the relevant agronomic requirements of agricultural machinery,128 hole trays were selected for mechanized transplanting seedling cultivation.Ecological characteristics of mechanized transplanted pepper and tomato seedlings were 25-35d seedling age;plant height between 100-150 mm,and true leaf number 4-6 pieces.The static trajectory equation of various points of the existing planting driving mechanism were analyzed,and the vertical displacement of the hanging point of the hanging cup of the planting driving mechanism was analyzed under the condition that the crank speed of the driving mechanism was 30 r/min,which provided a theoretical basis for the design of the opening and closing law of the hanging cup.The general structure and working principle of the hanging cup were expounded,and the requirements of the hanging cup operation were put forward(2)The spade-shaped cup and fork-shaped cup were designed.Firstly,the structural size of the seedling cup was designed according to the hanging method of the hanging cup of the existing planting mechanism and the requirements for falling seedlings.The structural size design of the shovel-shaped duckbill and the fork-shaped duckbill was completed for the problems existing in the transplanting operation.According to the general structural requirements of the hanging cup,the other parts of the hanging cup were designed in the three-dimensional software to ensure that the hanging cup can work normally.The hanging cup was virtual assembled and manufactured with the of the hanging cup structure assembly requirements.(3)The hanging cup opening and closing control mechanism was designed.According to the structural characteristics of the existing planting drive device,the cam swing-pull mechanism was designed to control the opening and closing of the hanging cup.The characteristics of the motion law of the follower of the cam mechanism were compared,and the law of the motion of the follower was determined as the law of sinusoidal acceleration.The relationship between the cam and the opening and closing of the hanging cup was analyzed,which contour curve and basic size of the cam were designed.The swing rods with different ratios of moving and resisting arms were designed to ensure the normal falling of the hanging cup.The design and virtual assembly of the basic structural dimensions of the cam swing mechanism was completed in 3D software.(4)The soil resistance and structural strength of the duckbill were analyzed by finite element analysis software.Dynamics analysis of three different duckbills was carried out by finite element simulation with Hypermesh,LS-DYNA and LS-PrePost software.The simulation factors included duck-billed structures:spade-shaped duckbill,fork-shaped duckbill,commonly used duckbill for transplanting,and soil entry speeds:0.013 mm/ms,0.33 mm/ms,0.67 mm/ms.Soil model was modeled by SPH algorithm.The simulation results showed that the soil penetration performance of spade-shaped duckbill and fork-shaped duckbill was better than that of common duckbill in transplanting.Static analysis of duckbill based on ANSYS-Workbench platform showed that the duckbill structure met the strength requirements.The maximum stress of the spade-shaped duckbill was 12.53 Mpa,and the fork-shaped duckbill was 115.33 Mpa.The maximum stress of the two kinds of duckbills was less than the allowable stress of the material.(5)The simulation results analysis of hanging cups penetration were verified to be constructed by the hanging cup soil resistance measurement platform.The experimental results showed that the relative errors of the measured data and the simulation results of the shovel-shaped duckbill,fork-shaped duckbill and transplanted common duckbill were 4.86%,1.38%and 4.42%respectively.The errors of the three kinds of cups were within the allowable range,and the feasibility of the simulation analysis was verified.An outdoor soil trough test platform was set up and hanging cups performance test of the outdoor soil trough was carried out.The planting performance of the shovel-shaped hanging cup and the fork-shaped hanging cup was tested by planting perpendicularity,seedling emergence rate and seedling burial rate.The results showed that the upright degree of two kinds of cup planting was more than 96%,the rate of seedling emergence and seedling burial was less than 3%,and the qualified rate of planting was above 94%,which met the industry standard. |
