| Pod pepper is one of the three characteristic peppers in Yunnan Province,which can be used for fresh food or processed food.At present,the main way to harvest pod pepper in Yunnan Province is manual harvesting,which is time-consuming and labor-intensive,and the research on pod pepper harvesting machinery is still blank.Therefore,aiming at the problems of high cost of manual harvesting,high labor intensity and difficult walking of self-propelled machinery in hilly and mountainous areas of Yunnan Province,a kind of pod pepper picking machine is designed according to the requirements of pod pepper harvesting.The specific research contents are as follows:(1)Determination of physical and mechanical properties of pod pepper.The agronomic parameters such as plant spacing,row spacing,plant height and expansion degree were measured by tape,and the fruit structure was introduced.The physical characteristic parameters such as fruit weight,density,static friction coefficient and water content were measured by electronic balance,measuring cylinder,slope instrument and infrared moisture meter.The binding force of fruit stalk-stem was measured by digital display push-pull meter.The fruit-stalk binding force test,peel shear test and peel tensile test were carried out by texture analyzer,and the mechanical properties such as peel elastic modulus and Poisson’s ratio were calibrated.The geometric parameters of the branches of pod pepper were measured by vernier caliper and protractor,and the average values of the length,diameter and angle of the branches at all levels were counted.Combined with the geometric parameters of fruit and fruit stalk,the fruit-branch simulation model was established.(2)Design of hand-held spiral comb-type pod pepper picking device.Based on the previous research on the pepper harvesting device and the analysis of the growth morphology of the pod pepper,two different picking schemes were proposed.Through theoretical analysis and feasibility verification test,the final scheme was determined to be a spiral comb structure scheme.Based on the theoretical analysis and calculation of the physical and mechanical parameters of the fruit and branches of pod pepper and the theoretical analysis and calculation of the picking process,the key component of the spiral comb picking device,the spiral comb component,is designed.The comb spacing is initially determined to be 3～8mm,and the comb helix angle is 0～20°;design and calculate the roller and drive shaft;through the theoretical calculation of the picking collision process,the picking speed is initially determined to be 8～20r/s,and then the motor selection calculation is carried out.(3)Pepper picking process simulation analysis.The rigid-flexible coupling model of picking was established in Adams 2020 software.Through the simulation of single fruit stress picking,the speed range of picking parts was preliminarily determined to be 10～20r/s under the premise of reducing the probability of fruit damage.Adams 2020 software was used to establish the picking fruit-branch model.The comb tooth spacing,spiral angle and rotation speed were selected as the test factors,and the number of picking pepper fruits was used as the test index to carry out the single factor simulation test.Finally,the horizontal range of comb tooth spacing was determined to be 3～8mm,the horizontal range of spiral angle was 0～20°,and the horizontal range of rotation speed was 10～20r/s.The finite element simulation analysis of the fruit-comb collision process was carried out by LS-DYNA.The maximum stress was obtained at 0.00056s during the collision between the comb and the fruit picking.The stress value was 1.397×10~7Pa,which was much smaller than the elastic modulus of the resin material 2600MPa.The comb will not be damaged,and the resin material is used to process the comb.(4)Field experiment of pod pepper picking device.Process and assemble the picking machine prototype;taking the net recovery rate,damage rate and branch rate as the evaluation indexes,the quadratic regression orthogonal rotation combination test design was adopted,and the test design was carried out with the comb tooth spacing,spiral angle and rotation speed as the test factors.The results show that the importance of affecting the net recovery rate is comb spacing,rotation speed and spiral angle.The importance of affecting the damage rate is rotating speed,comb spacing and spiral angle.The importance of affecting the branch rate is comb spacing,rotation speed and spiral angle.When the comb tooth spacing is 5.5mm,the spiral angle is 10°,and the rotation speed is 15r/s,the effect is the best.At this time,the net recovery rate is88.07%,the damage rate is 12.10%,and the branch rate is 22.05%. |
