| Panax notoginseng is one of the first perennial herbs of ginseng introduced in China.It has the good effects of promoting blood circulation,removing blood stasis,detumescence and pain relief.Therefore,it is also called "hemostatic divine medicine" by the people.In this paper,a pneumatic directional transplanting device of Panax notoginseng seedlings is developed,and an auxiliary seedling suction mechanism is set.The simulation analysis and experimental research are carried out.The results show that the designed directional transplanting device of Panax notoginseng seedlings can meet the agronomic requirements of directional transplanting.The specific research contents are as follows:(1)The basic physical characteristics of Panax notoginseng seedlings were measured,their intrinsic parameters and contact parameters were gained.Through 3 D scanning technology,obtained the Panax notoginseng seedlings contour model,respectively in the EDEM software using rapid filling method,API particles replacement method and the ball particles fast filling function model of Panax notoginseng seedlings and comparison analysis,finally choose the ball particles fast filling function as needed by the simulation analysis of the proposed model of Panax notoginseng seedlings discrete element model;The static stacking angle,dynamic stacking angle and inclined plate sliding test are simulated by using the calibration toolkit parameter calibration tool based on EDEM and Python to confirm the effectivity and precision of the parameter calibration test.(2)Combined with the agronomic requirements of directional transplanting of Panax notoginseng,a pneumatic directional transplanting device for Panax notoginseng seedlings was designed,its working principle was expounded,and the relevant structural parameters of key components were determined through theoretical calculation and analysis.Aiming at the problem of poor fluidity of Panax notoginseng seedlings,an eccentric wheel auxiliary seedling feeding mechanism is designed,and the simulation test is carried out with the help of EDEM software,taking the vibration frequency and vibration amplitude as the test factors.The best operating parameters of the auxiliary seedling suction mechanism are obtained,which promotes the separation of a single seedling from the population and is conducive to the adsorption of pneumatic directional transplanting device.(3)The force analysis and kinematics analysis of the four processes of suction,carrying,posture adjustment and positioning and seedling throwing of the pneumatic Panax notoginseng seedling directional transplanting device were carried out,and the conditions for stable adsorption of seedlings were determined.According to the Bernoulli principle and continuity principle,the process of generating rotating torque and realizing posture adjustment and positioning under the action of lifting force was obtained,and the mechanism of posture adjustment and positioning of seedlings was studied,The conditions for the seedlings to pass through the seedling carrying area were calculated,and the kinematic equation of the seedlings in the seedling feeding stage was established.(4)The flow field inside the main air chamber is simulated and analyzed by Fluent software,and the distribution of pressure and air velocity in the flow field inside the main air chamber and the better angle of rotation and attitude adjustment of seedlings caused by the main suction hole and attitude adjustment steering suction hole are determined;Using DEM-CFD gas-solid two-phase flow coupling simulation method,the process of seedling adsorption attitude adjustment is analyzed,and the feasibility of seedling attitude adjustment and positioning is verified by the lift generated by pressure difference;The process of adsorption and attitude adjustment of directional transplanting device was analyzed by EDEM field force one-way coupling method,and it was verified that the directional transplanting device can realize the adsorption of seedlings.(5)According to the pre-test results,taking the directional qualification index and leakage index as the test indexes,the negative pressure of the main suction hole,the rotating speed of the moving suction cup and the diameter of the attitude adjustment steering suction hole,which have a significant impact on the test indexes,are selected as the test factors for the single factor test.In order to further study the effects of quadratic and interactive terms of various factors on the working performance of directional transplanting device,based on the results of single factor test,the optimal operating performance parameters of directional transplanting device were studied by quadratic regression rotation orthogonal combination test.The results showed that when the diameter of the suction hole of the attitude adjustment steering was 4.5 mm,the negative pressure of the main suction hole was 1.03 ～ 2.11 k Pa,and the rotating speed of the moving suction cup was 4.67 ～ 6.08 r/min,the directional qualified index was 85.87% and the leakage index was 6.33%,which could meet the requirements of Panax notoginseng transplanting. |
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