| Potato is the fourth largest food crop in the world.Because of its resistance to cold,drought,and barrenness,it can adapt to most of the world’s farming environments.It has the characteristics of rich nutrition and high yield,and it is widely cultivated worldwide.After the potato harvest machinery,especially after the combine harvester,it contains a lot of dirt,rocks,roots and other debris.If it is not cleaned by dry cleaning equipment,but directly washed with water washing equipment,which consumes a lot of water and easy to block water washing equipment due to soil accumulation,need to manually remove the blockage frequently,affect the continuity of cleaning operations.Aiming at the problem that the existing potato cleaning equipment is mostly water washing equipment and lack of matching dry cleaning pretreatment equipment,a dry cleaning device that can be used in conjunction with water washing equipment is designed.The equipment adopts a rubber chain rod mechanism and is used in conjunction with a slender hair flexible brush roller mechanism,and realizes the potato cleaning operation through the displacement of the opposite differential motion.The main research work and conclusions of this topic are as follows:1.The basic physical and mechanical properties of potatoes and the types of impurities are studied.The statistical analysis of the three-axis size of the potato revealed that the size distribution of the length,width,and thickness of the potato basically obeys the normal distribution,and the shape is close to an ellipsoid.Compressive mechanical characteristics tests were carried out with indenter type,loading rate,loading direction and potato varieties as experimental factors,and the relationship between the force of the whole potato stem and mechanical damage was studied.A tensile test was conducted on potato skins,and the analysis showed that the difference in axial and radial elastic modulus and tensile strength of potato skins was small,and it could be regarded as an isotropic material.The types of impurities in potatoes were studied.It was found that the impurities are mainly roots,potato skins and residual leaves,and soil.The roots account for about 1/5 of the total impurities,potato skins and residual leaves account for about 1/5 of the total impurities,and the soil accounts for about 3/5 of the total Impurities.The above experimental data provide theoretical basis for the subsequent structure design and discrete element simulation test of potato dry cleaning device.2.In this paper,a kind of potato dry cleaning device is designed,which can complete the soil cleaning operation alone and can be used in conjunction with the washing equipment.The device adopts a rubber chain rod mechanism and a slender hair flexible brush roller mechanism to realize potato soil cleaning operations through dislocation and differential motion.The device is mainly composed of feed port,dithering mechanism,rubber chain rod mechanism,four groups of dislocation brush roller mechanism,transmission system,frequency conversion motor,discharge port,frame,etc.,which can be better complete the potato soil cleaning work.3.A discrete element simulation platform coupled with EDEM and Recur Dyn was built with potato dry cleaning device as the research objective.Take the number of collisions and force of the potato in the device as the evaluation index,and take the speed of the brush roller,the speed of the rubber chain rod,the feeding amount,and the speed ratio of the brush roller as the test factors to analyze the smoothness of the potato transportation and the degree of potato damage.Based on the EDEM API particle replacement function,the particle model of soil attached to the potato surface was established,and the discrete element simulation analysis was carried out to determine the separation effect of potato and soil by the dry cleaning device.The simulation results show that the dry cleaning device can transport smoothly and the separation effect of potato and soil is better.4.The feeding amount,the rotation speed of rubber chain rod,the rotation speed of brush roller and the ratio of the rotation speed of brush roller were selected as the test factors,and the soil removal rate and the potato damage rate were taken as the evaluation indexes.The single factor test was carried out to understand the influence rule and trend of each factor on the working performance of the machine.Single factor ANOVA analysis of the test data by SPSS Statistics showed that the feeding amount,the rotating speed of rubber chain rod and the rotating speed of brush roller had an extremely significant effects on the soil removing rate and the potato damage rate,while the rotating speed ratio of brush roller had significant effects on the soil removing rate and potato damage rate.5.According to the Box-Behnken test method,a three-factor and three-level analysis test was designed,and the potato damage rate and soil removal rate were analyzed by taking the feeding amount,the rotating speed of rubber chain rod and the rotating speed of brush roller as the test factors.The influence degree of each factor on the potato damage rate is ranked as follows:feeding amount X1>rubber chain rod rotation speed X2>brush roller rotation speed X3;The influence degree of each factor on soil removal rate is ranked as follows:feeding amount X1>brush roller speed X3>rubber chain rod speed X2.The optimal parameter combination of potato soil cleaning device was feeding amount of 3 t/h,rotation speed of rubber chain rod 23 r/min,rotation speed of the first and third brush rollers 38 r/min,and rotation speed of the second and fourth brush rollers 53 r/min.At this time,the rate of potato damage was 0.31%and the rate of soil removal was 91.11%,which meet the requirements of potato soil cleaning. |
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