Study On Energy Consumption Of Break System And Wear Of Fluted Roll Based On Discrete Element Method

Roller mill is an important equipment in the flour industry,used to process wheat into flour.Toothed roller is an important working component of the mill,mainly used in the leather grinding system of the mill.During the pulverizing process,the energy consumption and tooth roller wear of the leather mill are affected by multiple factors.Obtaining the influence rules of multiple factors on the energy consumption and tooth roller wear of the leather mill and predicting and analyzing the pulverizing and grinding process have important research significance,which is conducive to optimizing the pulverizing factors,reducing the energy consumption of the leather mill and reducing tooth roller wear.In response to the above issues,this paper takes 1B mill as the research object,and designs a set of experimental methods for grain parameter calibration based on the discrete element method.Based on the parameter calibration experiment,a discrete element model for leather mill milling is established,and the milling factors are analyzed and studied using the discrete element model.The main research contents are as follows:(1)The key factors that affect the energy consumption and tooth roller wear of the leather mill pulverizing process are analyzed,and they are classified into operation factors and tooth roller factors.The operation factors include feed flow rate and rolling distance,and the tooth roller factors include tooth roller service time and roller diameter.By analyzing the energy consumption and tooth roller wear in leather milling,a mathematical model of the energy consumption and tooth roller wear in leather milling was obtained,providing a theoretical basis for subsequent research.(2)Contact parameters affect the fluidity of wheat grains during flour milling,and are also important parameters in the discrete element model.In this paper,the contact parameters of wheat grains are obtained by studying the influence of discrete element contact parameters on the fluidity of wheat grains.The static friction coefficient of wheat toothed roller and the collision recovery coefficient of wheat toothed roller were measured by using the slope method and the free falling collision method,respectively,to obtain the value range of some contact parameters.The angle of repose formed by wheat accumulation is used to characterize the fluidity of wheat.According to the range of some contact parameters obtained from the previous experiments,Plackett Burman test,the steepest slope climbing test,and Box Behnken test are designed and conducted,respectively.The significant factors that affect the angle of repose of wheat and the regression equation for the impact of significant factors on the angle of repose are obtained.Taking the actual angle of repose as the response value,the contact parameters were obtained by solving the regression equation.(3)Using a texture analyzer,a uniaxial compression experiment was conducted to study the mechanical properties of wheat kernels after moistening.The Poisson’s ratio,elastic modulus,shear modulus,and critical load of wheat kernels were obtained to be 0.42,66.07MPa,23.26 MPa,and 90.00 N.Based on the above measured values,the mechanical parameters of the discrete element model for leather grinding powder were set.(4)To establish a discrete element model of wheat grains based on the Hertz-Mindlin with Bonding contact model,it is necessary to calibrate the parameters of the Bonding model of wheat grains,which affect the characteristics of the wheat crushing process in the discrete element model.Firstly,a single factor experiment was conducted to obtain the variation trend of the influence of Bonding model parameters on the critical load of wheat.Based on the results of a single factor experiment,a Box-Behnken experiment was designed using the critical load applied to the wheat grain bonding model as the response value,and a regression equation for the effect of wheat grain bonding model parameters on the critical load was obtained.According to the regression equation,the optimal values for the parameters of the Bonding model are:normal stiffness per unit area 3.61×10~9 N/m~3,tangential stiffness per unit area 1×10~9 N/m~3,critical normal stress 1×10~7 Pa,critical tangential stress 1×10~8 Pa。(5)Aiming at the problem that there are many influencing factors in leather grinding and the mechanism of multiple factors is still unclear,a discrete element model of leather grinding powder for a flour mill is established using the research method of discrete element analysis.Based on the discrete element model,multifactor experiments are conducted to study the relationship between milling factors on leather grinding powder power and tooth roller wear.Use a reading microscope to collect the grinding image of the tooth roller,establish a three-dimensional model of the tooth roller,and establish a discrete element model for skin milling and flour production based on the wheat grain contact parameters,mechanical parameters,and Bonding model parameters obtained from the aforementioned experiments.In order to study the effects of tooth roller usage time,roller diameter,feed flow rate,and rolling distance on leather mill pulverizing power and tooth roller wear,a discrete element model of leather mill pulverizing was used to design and conduct a Box-Behnken test.The significant factor ranking and regression equation of the test factors on leather mill pulverizing power and tooth roller wear were obtained,and the test factors were analyzed.(6)Taking mill 1B as the experimental object,the leather mill pulverizing power and tooth roller wear under actual operating conditions were obtained,and the reliability of parameter calibration experiments and regression equations was verified.Using a clamp type digital multimeter to measure the current value of the leather mill,and calculating the measured power,it was found that the measured power and the discrete element model regression equation power had a consistent numerical trend;Using a 3D profile measuring instrument,measure the 3D profile of the grinding teeth of the gear roller at different service times,and find that it is basically consistent with the wear trend of the gear roller in the discrete element analysis.The reliability of parameter calibration,discrete element model for leather mill pulverization,and regression equation has been proved.