Design And Experiment Of Shear Vibration Type Water Caltrop Sheller

Water caltrop is a special aquatic vegetable in China,widely grown in the middle and lower reaches of the Yangtze River and the Pearl River basin.After shelling and deep processing,we can obtain agricultural and sideline products with high nutritional value,which are loved by the nation and have high economic benefits.However,the hull of the water caltrop is hard,with an unusual shape,and the flesh is tightly connected to the hull,making it difficult to separate,at present,the basic use of manual hulling,but this method is time-consuming and labor-intensive,inefficient,which restricts the development of the horn industry.The research in the field of mechanical hulling of water caltrop at home and abroad is still relatively blank.To this end,this paper designed a shear vibration type water caltrop dehulling machine,the main content and conclusions of the full paper are as follows.（1）Calibration of water caltrop discrete element parameters.In response to the current situation where no accurate Hertz-mindlin with bonding model parameters are available for water caltrop crushing simulation tests.The average shearing force of the water caltrop was obtained from the uniaxial compression test as 352.95N,and this was used as the calibration target.Based on the Hertz-Mindlin with bonding model,a water caltrop discrete element model was established to carry out virtual calibration tests on bonding parameters,and the calibration range of each parameter was initially screened by single-factor tests.The two-level analysis factor test and the steepest climb test were used to quickly screen the significant factors and their calibration intervals,and the Central Composite response surface test was designed to solve the bonding parameters to determine the optimal combination of parameters in the discrete element model,and a rotary shear water caltrop simulation model was established to study the effects of different tools on water caltrop shear at different rotational speeds,which was used as a basis to design a shear vibration-type water caltrop sheller to carry out prototype tests to verify the reliability of the model.The results show that:x₁=4.818×10⁸N·m^-3,x₂=5.343×10⁸N·m^-3,x₃=1×10⁷Pa,x₄=1×10⁷Pa,and x₅=1.6mm.The shearing force of the simulated test is 352N,with an error of 0.269%;the minimum shearing force of the rectangular tool screened from the rotary shear test is 93.20N at 230rpm,with an error of0.215%from the predicted value of 92.99 N.（2）Shear vibration type hulling machine design.Firstly,it is clear that the design object is the deep processing of water caltrop,and the pre-treatment method of hulling is proposed;secondly,determine the technical requirements of the hulling machine for a hulling efficiency of 30 to 40 kg/h,shearing rate>70%,leakage rate<30%;then four sets of water caltrop hulling machine technical solutions are proposed,and the shearing and vibration type water caltrop hulling machine is determined as the final solution,the solution adopts the vertical stirrer uniform fabric,differential speed rotation feeding,pressure plate group and cutting plate limit,cross-cutting knife in the centre to cut the horn,vibration motor vibration to separate the shell and kernel and other technical solutions to achieve the hulling of water caltrop.The results show that the controllable parameters that have an influence on the movement of the water caltrop in the machine are:the pitch h of the vertical screw churn,the upper shaft speed w₁,the lower shaft speed w₂and the knife shaft speed w₃.（3）Based on the discrete element calibration of the water caltrop,the overall design of the machine and the mechanical analysis of the water caltrop movement,key operating parameters such as w₁,w₂,w₃,h,the model of the profile hole,the structure of the material tray,the tool thickness h_d,the knife edge angleγand the frequency of the vibrating disc are designed.Simulation tests were designed for the parameters to be designed,in conjunction with EDEM and ANSYS simulation analysis software.The specific tests and results are as follows:1)Cloth simulation test for the vertical spiral churn:Central Composite tests were designed for h and w₁,poisson regression fitting was carried out on the test results and the optimum combination of parameters was obtained based on the fitting results:h=45mm,w₁=45rpm.2)Water caltrop differential feeding simulation test:Based on the optimum upper shaft speed,a simulation model of differential feeding with water caltrop-shaped holes,circles and ellipses was developed for w₂and the shape of the hole design comparison test,a single-factor test was designed and based on the fitting results,w₂=30rpm and elliptical hole are the optimal results.3)Water caltrop rotary shear simulation test:Box-behnken Design（BBD）simulation test was carried out for w₃design comparison test and tool structure design,combined with the established diamond angle discrete element bonding parameter model,designed different tool models,established water caltrop rotary shear model,obtained tool force curves of different tool models at different rotational speeds,screened the optimal tool model as rectangular tool.And carry out further design of rectangular tool structure parameters,carry out BBD simulation tests on h_d,γ,w₃,and determine the optimal combinationofparametersas:h_d=1.6mm,γ=60°,w₃=230rpm.4)Modal analysis of vibrating discs:The vibrating disc is designed to have a diameter of 330mm and a height of 80mm,and the frequency of the vibrating motor is less than55Hz and the speed is less than 3300rpm without resonance of the vibrating disc.（4）Prototype shearing and vibrating type water caltrop dehulling machine was processed and tested,and shearing rateη₁,completion rateη₂,tool acquisition rateη₃,tool acquisition efficiency N₁and dehulling efficiency N₂were formulated as the evaluation criteria for the prototype test,and pre-tests of each mechanism and comparison tests of different pre-treatment methods were carried out to determine the test conditions at upper shaft speed w₁=45rpm,rated power of vibrating motor 30W,water caltrop-7℃refrigerated for 7 days and then soaked in water The test conditions of 1 night and then dehorning were carried out and prototype tests were carried out,resulting in the actual optimum working parameters of the prototype at the lower shaft speed w₁=20rpm and knife shaft speed w₃=280rpm,with shear rateη₁=100.0%,completion rateη₂=70.0%,tool acquisition rateη₃=81.4%,tool acquisition efficiency N₁=10.02kg/h and tool efficiency N₂=30.8kg/h,the machine tool efficiency N₂>30kg/h meets the technical requirements and the machine tool acquisition efficiency N₁reaches a maximum of 10.2kg/h.