CONTINUOUS TYPE BRIGHT HEAT TREATMENT FURNACE

摘要

PURPOSE:To effectively use an in-furnace atmosphere gas to execute a good bright heat treatment by providing an atmosphere mixing preventive device between a cleaning zone and heating zone and setting the atmosphere pressure of the heating zone at a high pressure. CONSTITUTION:The in-furnace atmosphere mixing preventive device 19 is provided at the boundary between the cleaning zone 15 and top roll chamber 16 of a bright heat treatment furnace 11. Nitrogen supplied from a throwing port 20 is blocked by the above-mentioned device 10 and flows against the passage of a steel strip 12, thereby flowing out of a sealing part 13A of a furnace inlet 13. The greater part of the gaseous AX thrown from a throwing port 23 into the heating zone 17 and cooling zone 18 flows out of a furnace outlet 14. Part thereof passes the top roll chamber 16 and the above-mentioned device 19 and flows out of the inlet 13. The flow rate of the gaseous AX passing device 19 is controlled by the pressures detected by pressure gages 26, 27 and the flow rates controlled by flow rate controllers 22, 25. The pressure on the top roll chamber 16 side of the heating zone 17 is always maintained higher than the pressure on the cleaning zone 15 side.