Analysis Of Flow Field Characteristics Of Texture Guide Roller-film Transmission System In Gravure Printing Machine

As an important component of gravure printing machine,the guide roller realizes the directional transmission of the webduring the high-speed operation.The flow field characteristic of the air entrainment between the guide roller andweb has a great influence on the stability of the web transmissionand printing quality.In this paper,the guide roller textured with microgrooves and transporting web are taken as the research objects.The air entrainment and flow field characteristics between the textured guide roller and web are studied.The influence of groove texture parameterson the flow field characteristics of the air entrainment is analyzed.The main works in this paper are present as follow:(1)Based on the theories of fluid lubrication and material mechanics,the continuity equation,the model of fluid constitutive relation,and the velocity equation of the flow field have been applied to deduce the theoretical model of flow field characteristic of air entrainment between the textured guide roller and web.Based on the elastic shell bending theory,the forces and moments in the transport of web have been analyzed to derived the equilibrium equation which provide the theoretical basis to analyze the flow field characteristics and the influence of surface texture on the transport stability of the web.(2)The theoretical model of flow field characteristic for the air entrainment between the guide roller and web,and the equilibrium equation are discretized by the finite difference method.The successive ultra-relaxation iterative method is applied to calculate the discrete equations.The air thickness and pressure distributionare obtained by the dynamic correction of flow field boundary of air entrainment.On this basis,the influence of the length-to-width ratio,printing speed and tension on the air thickness and pressure distribution of the air entrainment are analyzed.(3)The microgroove textures with different shapesare designed on the surface of guide roller.The theoretical model of flow field characteristic and equilibrium equation are calculated to analyze the influence of shapes,width,depth and number of textures on the air thickness and pressure distribution of the air entrainment.In order to improve the transportstability of web,the shape,width,depth and number of the texture are optimized to obtain the optimum shapes and range of structure parameter of textures.The works of this paper can provide a theoretical reference for the design and practical application of surface texture on the guide roller.The paper is studied to clarify the directional transporting mechanisms of the guide roller and the coupling relationship between the guide roller,web and entrained air.