Research on Vibration Control Method of Steel Strip for a Continuous Hot-dip Galvanizing Line

Nonlinear vibration of axially moving steel strip with tension near the air knife box during continuous hot-dip galvanizing process is investigated. A model of strip vibration for cooling section is established. Governing equations of the model are derived through the Hamilton's principle. Effect of speed, tension, molten zinc, oscillation of touch rolls and nonlinear wind load on strip vibration is considered. The reasonability of boundary conditions of the model is confirmed by comparison of results from theoretical method and numerical simulation. Averaging method is employed in solving the equations and obtaining displacement response. The relation between amplitude near the air knife and production parameters is studied and further solutions of vibration control is presented. The research reveals that speed of strip has noticeable effect on amplitude near the air knife. It will be more difficult to reduce vibration with the increase of speed. Larger tension is in favor of keeping away from peaks of amplitude by using speed adjustment. A scheme of vibration control based upon averaging method can meet the requirement of production. A vibration suppression proposal by improving support stiffness of touch rolls is suggested.