METHOD FOR CONTROLLING PRESSURE OF WIPING GAS IN CONTINUOUS HOT DIP COATING AND WIPING NOZZLE USING THERE OF

摘要

PROBLEM TO BE SOLVED: To provide a method for controlling the pressure of a wiping gas in continuous hot dip coating which is capable of preventing the occurrence of overcoating and splashing while preventing the occurrence of unequal strips and unequal appearance at the edges of a strip and is consequently capable of adjusting the thicknesses of the molten metal films on the front and rear surfaces of the strip to a prescribed thicknesses and producing the steel sheet beautifully plated on the front and rear surfaces. ;SOLUTION: The discharge region of the wiping gas is segmented to a standard discharge pressure region which has a width (L₁+2.L₂₁) obtd. by adding a width (L₂₁) of 100mm respectively to both sides of the width (L₁) of the strip 16 and where the wiping of the molten metal films on the front and rear surfaces of the strip 16 is executed by blowing the wiping gas under a prescribed discharge pressure (P₀) and a back pressure region which has a width (L₃₁) of ≥200mm respectively on both sides of the standard discharge pressure region and where the wiping gas is blown under a discharge pressure (P₁) lower than the discharge pressure (P₀) and higher than the atm. pressure.;COPYRIGHT: (C)1997,JPO