To deal with twists of a metallic strip during without moving problem by arranging an electric heater on the inner surface of a vertical type furnace body and directly heating the metallic strip moved in the vertical type furnace body.
In the vertical type furnace body 2, arch type refractory bricks 10 having non-parallel opposed two surfaces are arranged side by side in the circular direction and constructed as a cylindrical shape in the horizontal cross section. In the inner surface thereof, the electric heaters 11 are arranged side by side. An electric source supplying terminal 13 is connected with the electric heaters 11. A ceramic fiber 12 for heat insulating, is coated on the outer peripheral surface of the vertical type furnace body 2. The metallic strip 1 is shifted in the vertical type furnace body 2 and directly heated with the electric heaters 11 to a prescribed annealing temp. As the heat source besides, a radiant tube burner can be used. Even in the case of twisting the strip 1, since the strip is not brought into contact with the inner surface, any trouble in the shifting of the strip is not at all developed. By this constitution, since the surface area of the furnace body is small and the heat radiation can be reduced, the energy saving can be attained.
YOSHINAGA HIROHIKO
TAKEUCHI NAOTOSHI
HANADA YOSHITAKA
FUJISHIMA KYOICHI
TAWARA HIROSHI
TANAKA HIROSHI
DAIDO STEEL CO LTD
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