Design Of A New Type Of Grain Mill And Research On Key Components

Grains are more and more popular with consumers because of their nutritional and health effects,and the mill is an indispensable device for grinding grains into powder.The traditional mill requires multiple grinding,manual stirring and manual feeding.It is low processing efficiency,high labor intensity.Moreover,manual adjustment of the gap between the discs cannot ensure the uniformity of the powder particle size,which affects the milling effect,the nutritional value and the taste of the grains.Based on this,the research team developed a new type of automatic grain mill,which adopts the"pulverizing-disc grinding"milling process to solve the milling problem of traditional mills.The thesis studies the working mechanism and key components of the new automatic grain mill,and optimizes the parameters.The specific research contents include:(1)According to the needs of the grain mill,the structure of the new type of grain mill is designed,the pulverizing mechanism and disc grinding mechanism is summarized.Adopt human-computer interaction interface,use touch screen technology and PLC control technology to achieve automatic milling control.And the structure and parameters of key components are selected for optimization research.(2)The Fluent software was used to simulate the pulverization flow field,and designing single factor and orthogonal experiments to optimize the smashing mechanism and parameters.The results show that the pulverizing effect is better if the distribution scheme of the blades is in a spiral shape,the blade spacing is set to increasing(20-40)mm.The optimal scheme combination is obtained when the blade deflection angle is60~?,the blade length is120 mm,and the blade inclination angle is0~?.(3)Combining the theory and method of grinding disc design,the study of the division and tooth structure of the grinding plate is completed,and the structure parameters design of the grinding disc are completed.The Fluent software is used to carry out numerical simulation research on the powder flow field inside the grinding disc to explore the distribution of the flow field,the influence of the feeding speed on the pressure distribution of the flow field,and the shear stress distribution on the surface of the moving grinding disc.(4)Through the study of the theory of spiral conveyance,the structural design of the longitudinal spiral and the lateral spiral is completed.The discrete element analysis of the longitudinal spiral and the lateral spiral conveyance is performed by using EDEM software to explore the particle trajectory,the particle motion characteristics,the influence of the spiral parameters on the feed flow,etc.(5)The experiments of grain mill is carried out.Taking the pulverization rotating speed,the pulverization time and the disc gap as the influencing factors,the mathematical model is established with the particle size qualification rate and power consumption as the objective function.The experiments results is analyzed by Design-Expert software to perform regression analysis and response surface analysis.The optimal working parameter combination is pulverization rotating speed of 1500 r/min,pulverization time of 20 s,and disc gap of 0.045 mm.Under this condition,the particle size pass rate(more than 80 mesh sieve is qualified)reaches 90.5%,and the power consumption is 118 k J.