| 摘要 |
A method of manufacturing a hot dip coated metal strip includes the steps of depositing a molten metal coating solution on the surfaces of the metal strip by continuously dipping the metal strip in a coating bath, lifting the metal strip at a constant speed while supporting it with a pair of upper and lower support rolls for clamping the surfaces of the metal strip in the coating bath, adjusting the coating weights of the molten metal deposited on the surfaces of the metal strip by wiping the molten metal with gases from gas wiping nozzles disposed above the surface of the coating bath, and advancing the metal strip while supporting it with a pair of upper and lower touch rolls for clamping the surfaces thereof, wherein the metal strip is advanced by setting the distance L between the upper support roll disposed in the coating bath and the lower touch roll disposed outside the coating bath within the range determined by a formula L ≤ 80 x T x W<2>/V, where L: distance between the upper support roll in the coating bath and the lower touch roll outside the coating bath (mm), V: line speed of the metal strip (m/min), T: tension imposed on the metal strip (kgf/mm<2>), and W: target coating weight per one side of the metal strip (g/m<2>). According to the invention, the stable quality of the metal strip can be obtained by reducing the variation of the coasting weights of the molten metal deposited on the surfaces of the metal strip by reducing the variation of the coating weights of the molten metal deposited on the surfaces of the metal strip at all times regardless of the change of the operating conditions under which continuous hot dip galvanizing operation is carried out. Further, a coating cost can be greatly reduced by preventing the excessive deposition of the molten metal. <IMAGE> |
