JPS565918A - Method and apparatus for sealing door of heating furnace - Google Patents

Abstract

PURPOSE:To decrease the consumption of atmosphere gas remarkably and to prevent the oxidation of the surface of a steel sheet, by opening the upper, lower, right, and left doors at the irreducible minimum of a demand when the steel sheet enters or leaves an atmospheric heating furnace, and by bringing the top ends of the upper and the lower doors into contact with each other when the steel sheet has passed the entrance or exit. CONSTITUTION:To make a steel sheet pass through an entrance or exit, an upper door 5 and a lower door 6 are previously moved slightly upward and downward respectively, and a right door 11 and a left door 12 slightly rightward and leftward respectively. The steel sheet 1 enters through the opened entrance into the furnace and advances on the rolls 2 rightward while each door being brought into contact with the steel sheet completely at a suitable pressure, whereby the leakage of the atmosphere gas in the furnace is prevented nearly completely, simultaneously the entry of outside air is also prevented. When the rear end of the steel sheet 1 has passed through the entrance or exit by the rightward revolution of the rolls 2, the upper and the lower doors 5, 6 come into contact with each other without delay at their top ends, hereby the opening is closed and the doors wait for the passage of the next steel sheet 1.