PURPOSE: To obtain easily a steel plate having desired hardness from high to low hardness in a continuous annealing furnace having a heating zone, soaking zone and cooling zone by dividing the cooling zone to three zones, forming the furnace wall in the secondary cooling zone to have a heat insulating characteristic and enabling slow cooling and heat insulating in said zone.
CONSTITUTION: A heating zone 2, a soaking zone 3 and a cooling zone 21 are provided in series in a continuous annealing furnace 20. The zone 21 is divided to primary W tertiary cooling zones 22W24 which are connected in series. The heating and soaking of the plate 8 are accomplished by many radiant tubes 7 in the zones 2, 3. A gas jet device 25 is installed in the zone 22, and the quick cooling and slow cooling of the plate 8 can be accomplished adequately by said device which controls the flow rate of gas. The gas jet device has cooling capacity capable of wide range cooling. Cooling tubes 26 to be used in the case of cooling slowly the plate 8 are installed in the zone 23. A heat insulating refractory material 27 which insulates the heat of the plate 8 and performs over-aging is lined on the wall surface. A gas jet device 28 is installed in the zone 24 to cool the plate 8 to around the ordinary temp.
SHIMOYAMA YUUJI
YAGISHIMA AKIYA
| JPS5665937A | 1981-06-04 | |||
| JPS5080908A | 1975-07-01 | |||
| JPS5637291A | 1981-04-10 |
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