METHOD AND APPARATUS FOR PARTIALLY HOT DIPPING STEEL STRIP

摘要

PURPOSE:To manufacture a partially hot dipped steel sheet of high quality by forming a coated film of a soln. of a solid component on a side of a steel strip requiring no hot dipping and further forming a hot dipping preventing film contg. carbon powder on the wet coated film. CONSTITUTION:A side of a steel strip 1 requiring no hot dipping is coated with a soln. 2 of a solid component such as water glass by means of a reverse coater 3 to form a coated layer. While the layer is in a practically wet state, it is coated with carbon powder by means of a masking burner 4 to form a hot dipping preventing film. The strip 1 is passed through a drying furnace 5, introduced into an oxidizing furnace 6,and fed to a reducing furnace 8 through a throat 7. In the furnace 8 a side requiring hot dipping is cleaned by reducing oxide on the side. The strip is then dipped in a hot dipping bath 9. After regulating the amount of molten metal in the air with a gas spray nozzle 11, the hot dipped strip is passed through an alloying furnace 12 and a cooler 13, and the two-layer film on the side requiring no hot dipping is removed by grinding with a brushing roll 14.