Joo Ishihara1, Isao Ikuta1, Teturo Minemura1 and Masaichi Nagai1
1The Hitachi Research Laboratory, Hitachi, Ltd., Hitachi
Dimensional variation of the thickness across the width in an amorphous ribbon can be minimized in the double roller method by controlling sources of the dimensional non-uniformity. So, it is suitable in applications requiring many layers of metal ribbon. In the double roller method, however, since the surface temperature of roll rises rapidly, it has so far been thought that this method is unsuitable for the mass production. In this study, therefore, the water-cooling effect of rolls in the double roll method was investigated. Further, because a multiple-hole nozzle conventionally used in the double roller method is more expensive than a slit type nozzle, an attempt was made to modify the latter nozzle to apply to the double roller method.
At first, the surface temperature of the rolls was measured during the melt-ejection, and on the basis of this measurement, we tried to estimate the temperature by a numerical calculation using the finite difference method. Then the relations of the temperature rise in the rolls to the roll-materials, the diameter, the rotation speed and the width of ribbon were investigated. Behavior of metal flow from the nozzle was observed with high speed photography. Results obtained are summarized as follows:
(1) Since the melt flow from the slit type nozzle keeps a plane shape over the length up to 15 mm at maximum, this type nozzle can be applied to the double roller method.
(2) The maximum diameter of the rolls for which the slit type nozzle can be used is 200 mm.
(3) A Cu-Be alloy is most suitable for water-cooled rolls because of its high hardness and high thermal conductivity, but a steel roll is unsuitable for water-cooling because of its low thermal conductivity.
double roller method, production of amorphous metal ribbon, improvement of nozzle, water cooling effect of roll, roller material, mass production of amorphous ribbon
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