The Simulation Of The Design Of Rice Processing Equipment Based On The Mechanism Of Cutting Knife Roller

Rice milling is an important part in rice processing,and the quality of rice milling processing shows significant effect on the insurance on national food security.At present,a contradiction usually takes place between processing accuracy and broken rice rate in rice milling.Specifically,the excessive crush of rice leads to high broken rice rate,serious nutrition loss and high energy consumption of rice machines.Therefore,the investigation of the movement characteristics of rice grains during processing will be helpful to improve the traditional rice machining processing method.In this paper,the operating characteristics of a new rice machine based on the mechanism of cutting knife roller was studied.Firstly,the range of the rotation speed of the knife roller was determined by the statics experiments,then the research on the flow field and the movement of rice particles in the processing chamber was done by numerical simulation.Finally,the parameters of processing technology and the rice mill structure would be optimized.The main sections of this paper are shows as followings:1.The working principle and basic mechanical structure of the rice processing equipment based on the mechanism of cutting knife roller was determined.The machine can realize the instant monitor to the inlet and outlet particle temperature,motor voltage,current,power,spindle speed and wind pressure,so as to adjust the inlet air volume and the feed rate in time.2.In order to meet the requirements that the force of the rotation knife roller can shell and peel the rice without brown rice crushing,the static tests were carried out to several varieties of rice.The rotation speed range was 629.15-981.21 rpm for the 130 mm-diameter cutting knife roller.In order to judge if the inlet air pressure is reasonable or not,the parameters for the suspension of rice were calculated,and the suspension velocity should be at least 31.95 m/s,and the suspension pressure range should be 12.69-79.59 Pa.3.In order to study the influence of rice processing chamber parameters on the distribution of the internal airflow field,the flow field in the processing chamber was numerically simulated by using CFD software and taking the inlet air pressure and the processing chamber length as variables.The results showed that the wind pressure was positively correlated with the wind speed.At the condition of the wind pressure was 1500 Pa,the flow field in the processing chamber was relatively uniform when the range of the chamber length was 210-290 mm.4.The CFD-DEM coupling method was used to simulate the gas-solid two-phase flow of rice grains in the processing chamber.The effects of different factors on the rice movement were analyzed,such as the processing parameters,including knife roller speed and structural parameters,including the convex rib height,the edge number of regular polygon rice sieve and the diameter of knife roller.The simulation results of the single factor to the rice grain movement were shown as below: the average particle velocity,the average particle force,the particle collision energy and the number of collision were positively correlated with the rotation speed of the knife roller,the convex rib height,and the diameter of knife roller;the convex rib played a leading role in the process of particle translocation and mixing;the edge number of regular polygon rice sieve had a significant effect on the turbulence degree of particle motion,the turbulence degree increases first and then decreases with the increase of the edge number,the maximum were achieved when the edge number was seven.5.Therefore,in order to obtain the optimal combination to these parameters,the orthogonal numerical simulation test was carried out on the three main parameters: convex rib height,edge number of regular polygon rice sieve and the diameter of knife roller.The number of particle collisions,the particles resultant force and the standard deviation of force were used as evaluation indexes.And the optimal combination of parameters were obtained: the convex rib height was 10 mm,edge number of regular polygon sieve was seven,the diameter of the knife roller was 135 mm and the corresponding knife roller speed was 900 rpm.