Rapidly quenched Fe-based soft-magnetic alloy ribbon and its production method and core
A rapidly quenched Fe-based soft-magnetic alloy ribbon having wave-like undulations on a free surface, the wave-like undulations having transverse troughs arranged at substantially constant intervals in a longitudinal direction, and the troughs having an average amplitude D of 20 mm or less, is produced by a method comprising (a) keeping a transverse temperature distribution in a melt nozzle within ±15° C. to have as small a temperature distribution as possible in a melt paddle of the alloy, and (b) forming numerous fine linear scratches on a cooling roll surface by a wire brush, thereby providing a ground surface of the cooling roll with an arithmetical mean (average) roughness Ra of 0.1-1 μm and a maximum roughness depth Rmax of 0.5-10 μm.
1. A method for producing a quenched Fe-based amorphous alloy ribbon having wave-like undulations on a free surface by a single roll method, said wave-like undulations having transverse troughs arranged at longitudinal intervals, and said troughs having an average amplitude D of 20 mm or less, the method comprising the steps of (a) keeping a transverse temperature distribution in a melt nozzle within ±15° C. by using a heating nozzle having a slit-shaped opening for blowing a heating gas onto the melt nozzle, the length of the slit-shaped opening of the heating nozzle being 1.2-2 times the horizontal length of a slit-shaped orifice of the melt nozzle, the temperature of a heating gas ejected from the heating nozzle being 1000-1400° C.; and (b) forming numerous linear scratches on a cooling roll surface by a wire brush, thereby providing a ground surface of said cooling roll with an arithmetical mean (average) roughness Ra of 0.1-1 μm and a maximum roughness depth Rmax of 0.5-10 μm.
2. The method for producing a quenched Fe-based amorphous alloy ribbon according to claim 1 , wherein a hood is disposed, the melt nozzle and the heating nozzle being positioned in the hood, a gap being formed between the hood and the cooling roll.
3. The method for producing a quenched Fe-based amorphous alloy ribbon according to claim 1 , said wave-like undulations having ridges, wherein each of the ridges extends in a transverse direction in regions longitudinally adjacent to a trough.
4. The method for producing a quenched Fe-based amorphous alloy ribbon according to claim 1 , wherein regions having said troughs occupy 70% or more of the width of said ribbon, as determined by selecting five arbitrary regions of 50 mm long on the ribbon in a longitudinal direction and averaging transverse-direction occupancy ratios measured in these regions.
5. The method for producing a quenched Fe-based amorphous alloy ribbon according to claim 1 , wherein said troughs continuously extend the entire width of said ribbon.
6. The method for producing a quenched Fe-based amorphous alloy ribbon according to claim 1 , wherein said troughs have longitudinal intervals L in a range of 1-5 mm; and wherein said ribbon has a thickness T in a range of 15-35 μm.
7. The method for producing a quenched Fe-based amorphous alloy ribbon according to claim 1 , wherein a ratio t/T of an average height difference t between said troughs and said ridges to the thickness of said ribbon is in a range of 0.02-0.2.
8. The method for producing a quenched Fe-based amorphous alloy ribbon according to claim 1 , wherein the transverse troughs are curved like waves.
9. A method for producing a core, comprising forming a quenched Fe-based amorphous alloy ribbon by the method recited in claim 1 , and laminating or winding the quenched Fe-based soft-magnetic alloy ribbon.