Design And Experiment Of Astragalus Harvester Vibrating Shovel

Astragalus,also known as Heipiqi,Duqi,etc.,is a very common Chinese medicinal material with high medicinal value.With the widespread promotion of traditional Chinese medicine worldwide,the demand for astragalus at home and abroad is increasing year after year.However,for the harvesting of long-rooted crops such as astragalus,manual harvesting is labor intensive and costly.At present,the existing astragalus harvesting machine has problems such as insufficient operating depth,low operating efficiency,and poor harvest quality.The main reason is that the operating resistance is too large,which affects the relevant performance parameters.To this end,this topic uses the principle of vibration drag reduction to design a vibrating shovel equipped at the front of the astragalus harvester.The vibration of the front shovel is used to reduce the driving resistance which improve the operating depth,efficiency and quality.The main contents involved in this study are as follows:(1)According to the mechanism of vibration drag reduction,the effect of vibration drag reduction is directly affected by parameters such as vibration frequency,vibration amplitude,and driving speed of the implement.In this paper,in the ANSYS/LS-DYNA software,the soil model is established using MAT147 material that meets the revised Mohr-Coulomb criterion,and the dynamic simulation of the vibration cutting process of the excavation shovel is displayed.Using the orthogonal experiment method,the response surface of the driving resistance of the implement and the average deformation power of the soil to the vibration frequency,the amplitude of the shovel tip vibration,and the speed of the implement are obtained.Comprehensively considering the interaction relationship between related parameters,the relevant vibration parameters of the vibration excavating shovel are set as follows: the vibration frequency is 5 to 15 Hz,the vibration amplitude of the shovel tip is 15 mm,and the driving speed of the implement is 0.55 m/s.(2)Using ANSYS software in vibration excavation conditions,according to the difference of the up and down strokes,the stress analysis of the triangular shovel blades is carried out respectively,and the maximum stress and deformation of the up and down IV strokes are 192.5Mpa,191.9Mpa and 0.523 mm,0.482 mm,and according to the force cloud diagram,it was found that the middle part is prone to fatigue damage and the tip is prone to stress concentration defects.In this regard,we chose the claw toe of the mole cricket forefoot as the bionic object.Based on the extracted claw toe shape fitting curve,the bionic structure optimization of the middle,tip and side contours of the blade was carried out.The comparison of the simulation results proves that the maximum stress and deformation of the blade after optimization have decreased,and the safety factors of the up and down strokes have been increased from 2.2 and 2.2 to 2.9 and 3.7,respectively.(3)The design of the vibration excavation shovel is driven by an eccentric vibration mechanism,and three-dimensional modeling of the key parts is carried out in CATIA software.The upper and lower limit positions of the eccentric vibration mechanism were analyzed and calculated using the graphic method,and the eccentric distance of the eccentric wheel was set to 3.5 mm.The vibration mechanism model was imported into the ADAMS software,and its kinematics simulation was carried out.It was verified that the motion trajectories and motion laws of related parts met the design requirements.(4)The modal analysis of the vibration excavating shovel was carried out under the constraint state,and the first six order natural frequencies and vibration modes of the vibration excavating shovel were obtained.Among them,the natural frequencies of the first-order and second-order modes are 14.28 Hz and 23.38 Hz,respectively,and there is a risk of resonance with the vibration frequency of 5 to 15 Hz set above,so the vibration frequency of the excavation shovel was fine-tuned and the frequency was adjusted to 10 Hz.(5)Using the comparative experiment method,the improved model equipped with a vibrating shovel and the original model are subjected to actual field comparison tests.The comparison was performed from three aspects: operation depth,operation efficiency,and harvest quality.According to the test,the operating depth of the improved model is increased from 30.43 cm to 36.13 cm,the operating efficiency is increased from 2.3 mu/h to 2.4 mu/h,the harvester rate is increased from 94.6% to 95.4%,the damage rate is reduced from 5.1% to 2.1% and the total loss rate decreased from 7.3% to 5.4%.The performance parameters meet the design requirements and the improvement is obvious.