Research On Flow Field Characteristics Of Entrained Air Between Moving Web And Grooved Guide Roller

In the manufacturing process of thin film products such as flexible electronics,roll-to-roll manufacturing has the advantages of large area and low cost.In this manufacturing process,the guide roller plays an important role in the stable transmission of the moving film,but entrained gas will be formed when the guide roller rotates with the moving film.A proper amount of air can prevent defects such as scratches on the film.Slotting on the surface of the guide roller can reduce the amount of gas entrainment and improve the flow field characteristics of the gas entrained by the guide roller and the moving film,thereby further improving the stability of the printed film the overprint accuracy of the printed film and the quality of the film print.The main research contents of this article are as follows:(1)The characteristics of the air flow field between the moving film and the guide roller with a special surface structure are studied.The thin shell theory in elastic mechanics is used to analyze the force of the micro-element film at the guide roller,and the film deflection equation is established;the fluid lubrication theory and the fluid mass conservation equation are used to establish the air entrainment of the moving film and the slotted guide roller.Reynolds equation;combined with the structure function of the guide roller,the film thickness equation of the entrained gas is finally established.Finally,the influence of the moving film parameters,the parameters,the surface parameters of the guide roller and the radius on the flow field characteristics of the entrained gas are given.(2)A two-dimensional simulation model of the entrained gas between the guide roller and the moving film with different wrap angles is established,and the flow field of the entrained gas between the moving film and the guide roller is simulated and analyzed by FLUENT software.The velocity cloud diagram,streamline cloud diagram and dynamic pressure of the entrained gas are used to characterize the flowing field.Under the same other conditions as the radius of the guide roller,the same film velocity and the same other conditions,the influence of different wrap angles on the flow field of the entrained gas is analyzed and discussed to determine the best wrap angle of the model.(3)On the basis of the above,a three-dimensional simulation model of the smooth guide roller and the grooved guide roller are established,and the influence of the groove on the surface of the guide roller on the velocity and pressure of the flow field in the wrap angle area are compared and analyzed.After slotting,the flow of entrained gas is greatly improved,and the flow rate is also increased.The pressure transition on the surface of the film is relatively stable,indicating that the film at the slotting guide roller is not easy to lose stability when moving at high speed.