Structure Optimization Of The Whitening Chamber Of MNSW18 Low Temperature Rice Miller

With the development of agricultural machinery,a large number of machinery and equipment are involved in rice harvesting,storage,transportation,processing and other links.During this period,the collision between equipment and rice leads to an increase in the breaking rate of brown rice in subsequent processing.Rice with a high crushing rate is not only cheap,but also affects the taste of consumers.Therefore,improving the whole milled rice rate and reducing the crushing rate of rice has been a research topic for rice processing enterprises.At present,experts and scholars at home and abroad mainly focus on the study of static mechanics of rice and optimization of processing parameters of rice milling equipment,while ignoring the mismatch between physical and chemical properties of brown rice particles and performance parameters of rice milling machinery and equipment.The theoretical results showed that the mechanical properties of brown rice,whitening room gap,whitening roll speed and whitening time of brown rice were the key factors of rice crushing.Therefore,this paper explores the physicochemical properties of brown rice and the whitening and crushing mechanism,and the main research contents and conclusions are as follows:(1)Mechanical dynamics analysis of whitening and crushing of brown rice.Firstly,the motion pattern of the brown rice in the whitening room was analyzed,and it was found that the motion trajectory was a helical line,and the whitening speed formula of the helical motion of the brown rice grain relative to the whitening roller was deduced.It was found that the motion speed of the rice grain increased with the increase of the direction Angle of the collision velocity of the brown rice.Secondly,the stress condition of brown rice and its crushing phenomenon were analyzed.It was concluded that the rotational parameters of the roller and the geometric size of the spiral groove of the roller were the important factors affecting the crushing rate and whitening effect of the finished rice.Finally,the relative critical velocity formula of the mechanical stress damage caused by the collision between the brown rice particles and the whitening device was deduced.(2)Crushing characteristic test of brown rice.Firstly,the outer size of brown rice was defined and the sample size was measured to prepare for subsequent theoretical calculation and three-dimensional modeling of brown rice particles.Then,the whitening test was carried out on the brown rice samples with the optimal moisture content and the whitening clearance,roller speed and whitening time were investigated to investigate the effects of whitening clearance,roller speed and whitening time on the whitening crushing rate of brown rice,and the Origin software was used for data statistics.It was found that there was an exponential correlation between the speed of the whitening roller and the breaking rate of brown rice.With the increase of the speed of the sand roller,the breaking rate of brown rice increased gradually.Finally,Box-Behnken Design was carried out with Desk-Expert software to determine the main factors affecting the crushing rate of brown rice,and the optimal solution was obtained.The optimal whitening parameters were as follows: whitening clearance 11 mm,roller speed 1200r/min,and whitening time 40 S.Under these conditions,the whitening effect of brown rice was the best.(3)EDEM software was used to simulate the whitening process of brown rice.Firstly,the MNSW18 rice milling machine was modeled in three dimensions,and the structure of the rice milling machine was simplified according to the actual processing conditions.Then,the material parameters required for simulation were measured,and the whitening parameters at different roller speeds under each whitening gap were simulated,and each group of simulation data was derived for result statistics,and the movement trajectory,crushing situation and stress situation of brown rice particles were analyzed.The results showed that the motion curves of the inlet and outlet ends of the rice milling machine were irregular due to the large inlet pressure and the decrease of outlet pressure during the normal whitening process.When the roller speed exceeds 1400r/min under the whitening clearance of 8mm,the main factor affecting the whitening pressure changes from the whitening clearance to the roller speed.The faster the roller rotates,the more obvious the increasing trend of compression force is.