Investigation On The Effect Of Textured Guide Rollers On Web Transmission Stability

As one of the important components of gravure printing machine,the guide roller realizes the directional transmission of web during high-speed operation.During the operation of the gravure printing machine,the flow field characteristics between the guide roller and the moving web affect greatly the transmission stability of the web,and than affect the precision and quality of the printing.Therefore,the guide roller-web system in the high-speed gravure printing machine is taken as the object,and the micro textures are machined on the surface of the guide roller.On this basis,the flow field characteristics of the air entrainment between the textured guide roller and web are studied.The effects of texture parameters on the flow field characteristics is also analyzed to improve the quality of the printing.The main contents include:(1)Based on the momentum and continuity equations,the control equation for the flow field characteristics of the guide roller-web system are developed.The force model of the moving web is presented based on the elastic shell bending theory,and the equilibrium equation is obtained according to the relationship between the internal force of the web and the external load,which provides a theory for the analysis of the flow field characteristics of the guide roll-web system.(2)The Newton method is used to build the linear Reynolds equation for the gas lubrication of the guide roller-web system.By dynamically modifying the boundary of the air entrainment,the pressure and thickness distribution of the gas are obtained by using the finite difference method.On the basis,the influence of the printing speed,tension,and printing format of the web on the flow field characteristics of the guide roller-web system is investigated.(3)The groove texture is designed on the surface of the guide roller,and the flow field control model with air entrainment in the grooved guide roller-web system is developed.The finite difference method and Newton iteration method are used to calculate the pressure distribution and thickness of gas.On this basis,the influence of grooved texture parameters on the flow field characteristics of the guide roller-web system is analyzed.(4)In consideration of the phenomenon of slippage in the transmission of moving web and the asperity contact behaviors between the guide roll and web,the sliding model of textured guide roll-web system is developed.The critical gas film thickness that changes from mixed lubrication condition to solid contact condition,and the slip onset velocity of the moving web are obtained.The influence of grooved texture parameters and material properties of the web on the critical slip velocity is analyzed.