Metal treatment – Process of modifying or maintaining internal physical... – Magnetic materials
Reexamination Certificate
1998-08-18
2001-01-09
Sheehan, John (Department: 1742)
Metal treatment
Process of modifying or maintaining internal physical...
Magnetic materials
C029S605000
Reexamination Certificate
active
06171408
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention The invention relates to an inductive component having a strip-wound core which is wound from an amorphous ferromagnetic alloy, as well as to a production method for strip-wound core strips composed of amorphous ferromagnetic material.
2. Description of the Prior Art
In order to achieve good soft-magnetic characteristics, amorphous ferromagnetic alloys which are virtually free of magnetostriction must also be subjected to heat treatment. Typically, they are in this case tempered in a magnetic field in order to deliberately achieve a flat B-H loop.
The latter is carried out according to the prior art on ready-wound strip-wound cores since, as a rule, the amorphous material becomes brittle during tempering and the reduction in internal mechanical stresses required for maximum permeabilities can be achieved, these stresses being a result of production and also being caused by the winding of the strip-wound core.
One possibility for producing amorphous ferromagnetic strip-wound core strips which have been heat treated in a magnetic field is stationary heat treatment of the strip-wound core strips, which have been wound into coils for delivery, in so-called transverse-field furnaces. However, this method is highly critical with regard to good reproducibility. Since large amounts of material are involved, relatively long treatment times of several hours, and up to days in the worst case, must be carried out in order to ensure that the coils for delivery are uniformly heated through. Owing to the long treatment times, it is in this case necessary to operate at relatively low temperatures in the region of about 200° C.≦T≦250° C., in order to preclude thermal embrittlement of the material. However, this means that the variability range of the magnetic characteristics that can be achieved is very greatly limited, particularly with regard to the achievable permeabilities.
German Patentschrift 33 24 729 discloses a method for production of an amorphous magnetic alloy having a high permeability, in which a strip composed of an amorphous magnetic cobalt/basic alloy, which has a material proportion of iron of 5%, is produced by means of rapid solidification, and in which the amorphous magnetic strip is subjected to a magnetic field transversely with respect to the strip direction as it passes through heat treatment.
SUMMARY OF THE INVENTION
The invention is thus based on the object of developing this production method for strip-wound core strips composed of amorphous ferromagnetic material further such that strip-wound cores, in particular to form toroidal strip-wound cores, and inductive components produced from them can be produced economically and while saving energy, at low cost, and in the case of which components it is possible to achieve considerably higher permeabilities and, in consequence, improved magnetic characteristics.
This object is achieved according to the invention by a production method which is characterized by the following steps:
a) an amorphous ferromagnetic strip composed of a cobalt alloy which contains additives of iron and/or manganese in a material proportion of between 1 and 10% of the alloy is cast from a melt by means of rapid solidification;
b) the amorphous ferromagnetic strip is subjected to a magnetic field transversely with respect to the strip direction as it passes through heat treatment, the speed of movement being selected such that the amorphous ferromagnetic strip is heated to a temperature of 250°≦T≦450° C. for a heat treatment time of 0.5 s≦t≦60 s.
c) the strip-wound core strips are cut to length from the heat-treated, amorphous ferromagnetic strip.
The production method according to the invention can be carried out with the smallest possible amount of energy. Ductile, amorphous strip-wound core strips having flat B-H loops can be produced in this way which have a very highly linear response into their saturation region and have a permeability range of between about 2000 and 15,000. Owing to the capability to trim the magnetostriction precisely, the strips can be used to produce strip-wound cores, in particular toroidal strip-wound cores, which have a winding diameter of d≦10 mm, without any significant adverse effect on the magnetic characteristics.
Furthermore, no barrier gas is required in the course of the heat treatment and, in particular, the exposure to air is even advantageous since the thin oxidation layer produced on the strip-wound core strips assists the required electrical strip layer insulation.
Particularly excellent strip-wound core strips can be achieved at speeds of movement which are set such that the amorphous ferromagnetic strip is heated to a temperature of 300° C.≦T≦400° C. for a heat-treatment time of t≦30 s.
In a development of the invention, the proportion of iron and/or manganese in the alloy is set such that the amorphous ferromagnetic strip has a saturation magnetostriction of &lgr;
s
≦0.1 ppm, preferably &lgr;
s
≦0.05 ppm, after the heat treatment.
In the case of the inductive component according to the invention, the strip-wound core is accordingly wound from a ductile, heat-treated strip-wound core strip composed of an amorphous ferromagnetic alloy, the amorphous ferromagnetic alloy having a saturation magnetostriction of &lgr;
s
≦0.1 ppm as well as a flat B-H loop which runs as linearly as possible into the saturation region. The amorphous ferromagnetic alloy is in this case a cobalt-based alloy which contains material proportions of iron and/or manganese of between 1 and 10% by atomic weight of the alloy. The strip-wound core strip is thus heat-treated before being wound and, as a result of the ductility achieved, the strip-wound cores can be wound without any problems.
Depending on the quality being aimed for and the desired versatility of the inductive component, the strip-wound cores can have a mean diameter of d≦50 mm, and even a mean diameter of d≦10 mm.
In particular, inductive components can be produced which have toroidal strip-wound cores.
REFERENCES:
patent: 4525222 (1985-06-01), Meguro et al.
patent: 4668309 (1987-05-01), Silgailis et al.
patent: 4769091 (1988-09-01), Yoshizawa et al.
patent: 5256211 (1993-10-01), Silgailis et al.
patent: 5568125 (1996-10-01), Liu
patent: 5676767 (1997-10-01), Liu et al.
patent: 5757272 (1998-05-01), Herzer et al.
patent: 33 24 729 C2 (1991-01-01), None
patent: 0 737 986 A1 (1996-10-01), None
Abstract for Japanese Application No. 64-152122 dated Jan. 28, 1991.
Emmerich Kurt
Herzer Giselher
Schiff & Hardin & Waite
Sheehan John
Vacuumschmelze GmbH
LandOfFree
Process for manufacturing tape wound core strips and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for manufacturing tape wound core strips and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for manufacturing tape wound core strips and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2473333