| 摘要 |
PURPOSE:To prevent the flawing on the surface of a metallic strip by providing floating devices in a heat treatment furnace, ejecting the high-temp. gas generated out of the furnace from the bottom surface side of the strip and heat-treating the catenary-supported strip. CONSTITUTION:The floating devices 4a, 4b, 4c are provided in the direct fire type continuous heat treatment furnace 1 and a floating device 5 is provided to the outside of the furnace. The metallic strip 3 is heat-treated by side firing burners 6 while said strip is catenary-supported in the furnace 1 between an out-of-furnace roll 2 on the inlet side and the floating device 5 on the outlet side. The high temp. gas is ejected from the devices 4a, 4b, 4c to the bottom surface side of the strip 3. The high-temp. gas is the out-of-furnace gas different of the in-furnace gas obtd. by introducing air and gaseous fuel through conduits 10a, 13a into a heater 11a to burn the air and fuel and supplying the resultant gas through a conduit 12a to the device 4a (the same holds true of the other devices 4b, 4c). The use of rolls is thus abolished and the flawing on the surface of the strip 3 in the furnace is prevented.
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