EP1407462A2

EP1407462A2 - Method for producing nanocrystalline magnet cores, and device for carrying out said method

Info

Publication number: EP1407462A2
Application number: EP02745429A
Authority: EP
Inventors: Jörg PETZOLD; Volker Kleespies; Hans-Rainier Hilzinger
Original assignee: Vaccumschmelze GmbH and Co KG
Current assignee: Vaccumschmelze GmbH and Co KG
Priority date: 2001-07-13
Filing date: 2002-07-11
Publication date: 2004-04-14
Anticipated expiration: 2022-07-11
Also published as: US7563331B2; US7964043B2; WO2003007316A3; WO2003007316A2; DE10134056B4; CN100380539C; US20040112468A1; CN1505822A; DE10134056B8; EP1407462B1; DE10134056A1; US20100018610A1; JP2004535075A

Abstract

The invention relates to a method and to a device for carrying out a manufacturing process in which all magnet cores to be produced are first continuously crystallized. Depending on whether the required hysteresis loops should be round, flat or rectangular, the magnet cores are either immediately finished, that is enclosed in housings, conditioned to a rectangular hysteresis loop in a direct-axis magnetic field or to a flat hysteresis loop in a magnetic cross-field and then finished.

Description

description

Process for producing nanocrystalline magnetic cores and device for carrying out the process

The invention relates to a method for producing nanocrystalline magnetic cores and devices for carrying out such a method.

Nanocrystalline soft magnetic iron-based alloys have been known for a long time and have been described, for example, in EP 0 271 657 B1. The soft magnetic iron-based alloys described there generally have a composition with the formula:

(Feχ-a _a ) ₁₀₀ _ _x _ _y _ _z _ _α Cu _x Si _y B _z M ' _α

where M is cobalt and / or nickel, M> at least one of the elements niobium, tungsten, tantalum, zirconium, hafnium, titanium and molybdenum, the indices a, x, y, z and α each have the condition 0 <a < 0.5; 0.1 <x <3.0; 0 <y <30.0; 0 <z <25.0; 5 <y + z <30.0 and 0.1 <α <30.

Furthermore, the soft magnetic iron-based alloy can also have a composition with the general formula

(Fei-a M _a ) ₁₀₀ _ _x _ _y _ _z _ _α _ß_ _γ Cu _x Si _y B _z M ^» _α M" ßXγ

have, where M is cobalt and / or nickel, M ^{v is} at least one of the elements niobium, tungsten, tantalum, zirconium, hafnium, titanium and molybdenum, M ^{vx is} at least one of the elements vanadium, chromium, manganese, aluminum, an element of the platinum group , Scandium, yttrium, a rare earth, gold, zinc, tin and / or rhenium and X is at least one of the elements carbon, germanium, phosphorus, gallium, antimony, indium, beryllium and arsenic and where a, x, y, z, α, ß and γ each the condition 0 ≤ a <0.5, 0.1 <x <3.0, 0 <y <30.0, 0 <z <25.0, 5 <y + z <30.0, 0.1 <α <30.0, β <10.0 and γ <10.0.

In both alloy systems, at least 50% of the alloy structure is occupied by fine crystalline particles with an average particle size of 100 nm or less. These soft magnetic nanocrystalline alloys are increasingly being used as magnetic cores in inductors for a wide variety of electrical engineering applications. For example, summation current transformers for AC-sensitive and also pulse-current-sensitive residual current circuit breakers, chokes and transformers for switched-mode power supplies, current-compensated chokes, smoothing chokes or transducers made from tape cores, which have been produced from tapes from the nanocrystalline tapes described above, are known. This is evident, for example, from EP 0 299 498 B1. Furthermore, the use of such toroidal cores is also known for filter sets in telecommunications, for example as an interface transmitter in ISDN or DSL applications.

The nanocrystalline alloys in question can be produced inexpensively, for example, using what is known as rapid solidification technology (for example using melt spinning or planar flow casting). An alloy melt is first provided, in which an initially amorphous alloy is then produced by rapid quenching from the melt state. The cooling rates required for the alloy systems in question are about 10 ⁶ K / sec. This is achieved with the help of the melt spin process, in which the melt is sprayed through a narrow nozzle onto a rapidly rotating chill roll and solidifies into a thin band. This process enables the continuous production of thin tapes and foils in a single operation directly from the melt at a speed of 10 to 50 m / sec, whereby tape thicknesses of 20 to 50 μm and tape widths of up to a few cm are possible. The initially amorphous tape produced using this rapid solidification technology is then wound into magnetically variable magnetic cores, which can be oval, rectangular or round. The central step in achieving good soft magnetic properties is the "nanocrystallization" of the alloy strips, which were still amorphous until then. From a soft magnetic point of view, these alloy strips still have poor properties because they have a relatively high magnetostriction | λg | of approximately 25 x 10 ^"6. When a crystallization heat treatment tailored to the alloy is carried out, an ultrafine structure is created, ie an alloy structure is formed in which at least 50% of the alloy structure is occupied by body-centered FeSi crystallites. This Crystallites are embedded in an amorphous residual phase made of metals and metalloids. The solid-state physical background for the formation of the fine crystalline structure and the consequent drastic improvement in the soft magnetic properties is described, for example, in G. Herzer, IEEE Transactions on Magnetics, 25 (1989) , Pages 3327 ff. This gives rise to good soft magnetic properties such as high permeability or small hysteresis losses by averaging the crystal anisotropy K _{u of} the randomly oriented nanocrystalline "structure".

According to the state of the art known from EP 0 271 657 B1 or 0 299 498 B1, the amorphous strips are first wound on ring winding cores with as little tension as possible on special winding machines. For this purpose, the amorphous band is first wound into a round ring band core and - if necessary - brought into a shape deviating from the round shape by means of suitable shaping tools. By using suitable winding bodies, shapes that deviate from the round shape can also be achieved directly when winding the amorphous tapes into toroidal tape cores. Then, according to the state of the art, the tension-free wound ring band cores are subjected to crystallization heat treatment in so-called retort furnaces, which is used to achieve the nanocrystalline structure. Here, the toroidal cores are stacked one above the other and inserted in such an oven. It has been shown that a decisive disadvantage of this method is that weak magnetic stray fields, such as. B. the magnetic earth field is induced a position dependence of the magnetic values in the magnetic core stack. For example, while high permeability values with an intrinsically high remanence ratio of more than 60% are present at the stack edges, the magnetic values in the area of the stack center are characterized by more or less pronounced flat hysteresis loops with low values with regard to permeability and remanence.

This is shown, for example, in FIG. 1. FIG. 1 a shows the scatter of the permeability at a frequency of 50 hearts as a function of the running core number within a glow stack. FIG. 1b shows the dependence of the remanence ratio B _r / B _m as a function of the sequential core number within a glow stack. As can be seen from FIGS. 1 a and 1 b, the distribution curve for the magnetic values of a production line for annealing products is wide and continuous. The distribution curve drops monotonically towards high values. The exact specific course depends on the alloy, the magnetic core geometry and of course the stack height.

In the case of the nanocrystalline alloy systems in question, the setting of the nanocrystalline structure is typically carried out at temperatures from T _a = 450 ° C. to 620 ° C., the necessary holding times being between a few minutes and approximately 12 hours. In particular, US Pat. No. 5,911,840 shows that with nanocrystalline magnetic cores with a round BH loop, a maximum permeability of μ _max = 760,000 is achieved when a stationary temperature turplateau with a duration of 0.1 to 10 hours below the temperature required for the crystallization of 250 ° C to 480 ° C is used to relax the magnetic core. This increases the duration of the heat treatment and thus reduces the economy.

The present invention is based on the discovery that the magnetostatic parabolas shown in FIGS. 1 a and 1 b in the stack annealing of toroidal cores in retort furnaces are magnetostatic in nature and are due to the location-dependent demagnetization factor of a cylinder. Furthermore, it has been found that the exothermic heat of the crystallization process, which increases with the core weight, can only be released incompletely to the surroundings of the glow stack and can therefore lead to a significant deterioration in the permeability values. It is noted that nanocrystallization is of course an exothermic physical process. This phenomenon has already been described in JP 03 146 615 A2. The result of this inadequate removal of the heat of crystallization is a local overheating of the toroidal cores within the stack, which can lead to lower permeabilities and higher remanence. Accordingly, the permeability and remanence of cores in the center of the glow stack are lower than the permeability and remanence of toroidal cores at the outer ends of the glow stack. So far this problem has been circumvented, as far as it has been recognized at all, in that, for example, just as in US Pat. No. 5,911,840, in the area of the onset of nanocrystallization, that is to say from about 450.degree. C., the heating has been very slow in an uneconomical manner. Typical heating rates were between 0.1 and 0.2 K / min. , which alone the passage through the area up to the temperature of 490 ° C could be up to 7 hours. This procedure was very uneconomical. The object of the present invention is therefore to provide a new method for producing toroidal tape cores, in which the aforementioned problem of parabolic scattering and other, in particular exothermic, deteriorations in magnetic characteristics can be avoided, and which works particularly economically.

According to the invention, this object is achieved by a process for the production of toroidal tape cores of the type mentioned at the outset, in which the completely wound amorphous toroidal tape cores are heat-treated in a continuous manner to form nanocrystalline toroidal tape cores.

The separation of the toroidal cores creates an identical magnetostatic condition for each individual toroidal core. The consequence of this magnetostatic crystallization condition, which is identical for each individual ring band core, results in the elimination of the "parabola effect" shown in FIGS. 1 a and 1 b and thus a limitation of the scattering to alloy-specific, geometric and / or thermal causes.

The heat treatment of the unstacked amorphous toroidal cores is preferably carried out on heat sinks which have a high heat capacity and a high thermal conductivity, which is also already known from JP 03 146 615 A2. A metal or a metallic alloy is particularly suitable as the material for the heat sinks. The metals copper, silver and heat-conductive steel in particular have proven to be particularly suitable.

However, it is also possible to carry out the heat treatment on a ceramic heat sink. Furthermore, an embodiment of the present invention is also conceivable in which the amorphous toroidal cores to be treated are introduced into a mold bed made of ceramic powder or metal powder, preferably copper powder. Magnesium oxide, aluminum oxide and aluminum nitride have proven to be particularly suitable as ceramic materials, both for a solid ceramic plate or for a ceramic powder bed.

The heat treatment for crystallization is carried out in a temperature interval of approx. 450 ° C to approx. 620 ° C, whereby the heat treatment runs through a temperature window of 450 ° C to 500 ° C and thereby with a heating rate of 0.1 K / min to approx 20 K / min is run through.

The invention is preferably carried out with a furnace, the furnace having a furnace housing which has at least one annealing zone and a heating source, means for supplying the annealing zone with unstacked amorphous magnetic cores, means for conveying the unstacked amorphous magnetic cores through the annealing zone and means for Removal of the unstacked heat-treated nanocrystalline magnetic cores from the annealing zone.

A protective gas is preferably applied to the annealing zone of such a furnace.

In a first embodiment of the present invention, the furnace housing has the shape of a tower furnace in which the annealing zone runs vertically. The means for conveying the unstacked amorphous magnetic cores through the vertically running annealing zone are preferably a vertically running conveyor belt.

The vertically running conveyor belt has supports perpendicular to the conveyor belt surface made of a material with a high heat capacity, ie either from the metals described above or the ceramics described at the outset, which have a high heat capacity and high thermal conductivity. ability. The toroidal cores lie on the supports.

The vertically extending annealing zone is preferably divided into several separate heating zones, which are provided with separate heating controls.

In an alternative embodiment of the furnace according to the invention, it has the shape of a tower furnace in which the annealing zone runs horizontally. The horizontally running annealing zone is in turn divided into several separate heating zones, which are provided with separate heating controls. At least one, but preferably a plurality of support plates rotating about the tower furnace axis is then provided as the means for conveying the unstacked amorphous toroidal cores through the horizontally extending annealing zone.

The support plates in turn consist entirely or partially of a material with high thermal capacity and high thermal conductivity on which the magnetic cores rest. In particular, metallic plates that come from the metals mentioned at the outset, ie. H. i.e. copper, silver or heat-conductive steel.

In a third alternative embodiment of the furnace according to the invention, it has a furnace housing which has the shape of a horizontal continuous furnace, in which the annealing zone in turn runs horizontally. This embodiment is particularly preferred because such an oven is relatively easy to manufacture.

A conveyor belt is provided as a means of conveying the unstacked amorphous toroidal cores through the horizontally extending annealing zone, the conveyor belt preferably being provided with supports which consist of a material with high thermal capacity and high thermal conductivity, on which the toroidal cores rest. Come here again the metallic and / or ceramic materials discussed at the beginning.

Typically, the horizontally running annealing zone is again divided into several separate heating zones, which are provided with separate heating controls.

In a further development of the present invention, the magnetic cross-field treatment required for the production of flat hysteresis loops can also be generated directly and simultaneously in one pass. For this purpose, at least a part of the flow channel enclosed by the furnace housing is guided between the two pole pieces of a magnetic yoke, so that the magnetic cores passing through are subjected to a homogeneous magnetic field in the axial direction, thereby forming a uniaxial anisotropy transverse to the direction of the wound band. The field strength of the yoke must be so high that the magnetic cores are at least partially saturated in the axial direction during the heat treatment.

The hysteresis loops become flatter and linear, the greater the proportion of the length of the furnace channel over which the yoke is placed.

In all three alternative configurations of the furnace according to the invention, the separate heating zones have a first heating zone, a crystallization zone, a second heating zone and a maturing zone.

The invention is illustrated below with reference to the drawing, for example. Show:

FIG. 2 shows the influence of the toroidal core weight on the permeability (50 Hz) of toroidal cores continuously annealed without a heat sink, FIG. 3 shows the influence of heat sinks of different thicknesses on the exothermic crystallization behavior of continuously annealed toroidal cores.

FIG. 4 shows the influence of different thicknesses of heat sinks on the maximum permeability of continuously annealed toroidal cores of different geometry and different toroidal core mass,

FIG. 5 shows the influence of the toroidal core weight on the permeability (50 Hz) after continuous annealing on a 10 mm thick copper heat sink,

6 shows the end faces of two comparison toroidal cores after continuous annealing without heat sink and with

Heat sink

FIG. 7 schematically, in cross section, a tower furnace according to the invention with a vertically running conveyor belt,

FIG. 8 shows a multi-storey carousel oven according to the invention,

9 shows a continuous furnace according to the invention with a horizontally running conveyor belt and

10 shows a transverse field generation by means of a yoke over the furnace channel.

Annealing processes are required in particular for the production of so-called round hysteresis loops, which allow the formation and maturation of an ultrafine nanocrystalline structure under field-free and thermally exact conditions as possible. As mentioned at the beginning, according to the prior art, the annealing is normally carried out in so-called retort furnaces, in which the magnetic cores are inserted stacked one above the other. The decisive disadvantage of this method is that weak stray fields such. B. the magnetic field of the earth or similar stray fields, a position dependence of the magnetic parameters in the magnetic core stack is induced. This can be called the antenna effect. While there are actually round hysteresis loops with a high permeability and an intrinsically related high remanence ratio of more than 60% at the stack edges, there are more or less pronounced flat hysteresis loops with lower permeabilities and remanence ratios in the middle of the stack. This was initially shown in Figures la and lb.

Accordingly, the distribution curve for the magnetic characteristics of a production batch runs broadly, steadily and drops monotonically towards high values. As mentioned at the beginning, the exact course depends on the soft magnetic alloy used, the magnetic core geometry and the stack height.

In addition to the magnetostatic parabolic formation, stack annealing in retort furnaces has the further disadvantage that the exothermic heat of the crystallization process can only be released to the environment incompletely with increasing magnetic core weight. The result is overheating of the stacked magnetic cores, which can lead to lower permeabilities and high coercive field strengths. To avoid these problems in the area of the onset of crystallization, i. H. So from about 450 ° C are heated very slowly, which is uneconomical. Typical heating rates are 0.1 to 0.2 K / min, which means that the passage through the area up to 490 ° C can be up to 7 hours.

The only economically feasible large-scale alternative to batch annealing in the retort furnace lies in annealing in accordance with the present invention in a continuous process. By separating the magnetic cores through the continuous process identical magnetostatic conditions are created for each individual magnetic core. The result is the elimination of the parabolic effects described above, which cause scattering on alloy-specific, nuclear technology and thermal causes.

While the first two factors are easy to control, the rapid heating rate typical of continuous annealing can lead to exothermic heat development even with isolated magnetic cores, which, according to FIG. 2, causes damage to the magnetic properties that increases with the core weight. FIG. 2 shows the influence of the magnetic core weight on the magnetic values (μio ~ Mmax) if the magnetic cores are heat-treated directly in the pass without a heat sink.

Since delayed heating would lead to an uneconomical multiplication of the length of the throughput section, this problem can be solved by introducing heat-absorbing underlays (heat sinks) made of good heat-conducting metals or by metallic or ceramic powder beds. Copper plates have proven to be particularly suitable, since they have a high specific heat capacity and very good thermal conductivity. This means that the exothermic heat of crystallization can be extracted from the front of the magnetic cores. In addition, such heat sinks reduce the heating rate, which can further limit the exothermic overtemperature. This is illustrated by FIG. 3. FIG. 3 shows the influence of differently thick copper heat sinks on the exothermic behavior in toroidal tape cores, which had dimensions of approximately 21 x 11.5 x 25 mm.

Since the rate of temperature equalization depends on the temperature difference between the magnetic core and the heat sink, the thermal capacity of the magnetic core must be adapted to the mass and height of the magnetic core. FIG. 4 shows the influence of the thickness of the heat sinks on the maximum permeability of toroidal cores of different geometries or magnetic core masses. While, according to FIG. 4, a 4 mm thick copper heat sink already leads to good magnetic characteristics for magnetic cores with a small core weight and / or a small magnetic core height, heavier or higher magnetic cores require thicker heat sinks with a higher heat capacity. It has emerged as an empirical rule of thumb that the plate thickness should be d> 0.4 x the core height h.

As can be seen from FIG. 5, taking this rule into account, excellent magnetic characteristics (μ _ax (50 Hz)>500,000;μi> 100,000) can be achieved over a wide weight range.

The lowering of the magnetic properties in continuous annealing without heat sinks is usually associated with lamellar warpage and kinking of the strip layers, as can be seen from FIG. 6. FIG. 6 shows the end faces of two toroidal cores measuring 50 x 40 x 25 mm ³ after continuous annealing without a heat sink (left core) and on a 10 mm thick copper heat sink (right core). With the right nucleus there were practically no faults on the front side. When left magnetic core, however, the maximum permeability is μ _m ax = 127,000, whereas it was approximately 620,000 at the right magnetic core.

It has been shown that good magnetic characteristics can only be achieved if more than approximately 85% of the end faces of a core are free of distortion.

FIG. 7 schematically shows a first embodiment of the present invention, a so-called tower furnace. The tower furnace has a furnace housing in which the annealing zone runs vertically. The unstacked amorphous magnetic cores are conveyed through a vertically running annealing zone by a vertically running conveyor belt.

The vertical conveyor belt has heat sinks made of a material with a high heat capacity, preferably copper, which are perpendicular to the conveyor belt surface. The ring band cores lie with their end faces on the supports. The vertical annealing zone is divided into several separate heaters, which are provided with separate heating controls.

Another embodiment of the present invention is illustrated in FIG. Again, the shape of the furnace is that of a tower furnace, but the annealing zone is horizontal. The horizontally running annealing zone is in turn divided into several separate heating zones, which are provided with separate heating controls. As means for conveying the unstacked amorphous toroidal cores through the horizontally extending annealing zone, one, but preferably several, support plates rotating around the tower furnace axis are provided, which serve as heat sinks.

The support plates in turn consist entirely or partially of a material with high thermal capacity and high thermal conductivity, on which the magnetic cores rest with their end faces.

Finally, FIG. 9 shows a third particularly preferred alternative embodiment of the present invention, in which the furnace housing has the shape of a horizontal continuous furnace. The annealing zone again runs horizontally. This embodiment is particularly preferred because, in contrast to the two ovens mentioned above, such an oven can be produced with less effort. The ring belt cores are conveyed through the horizontally extending annealing zone on a conveyor belt, the conveyor belt preferably being provided with supports which serve as heat sinks. Again, copper plates are particularly preferred. In an alternative embodiment of the transport plates are taken as heat sinks that slide through the furnace housing on rollers.

As can be seen from FIG. 9, the horizontally running annealing zone is in turn subdivided into several separate heating zones which are provided with separate heating controls.

In a special embodiment of the continuous furnace shown in FIG. 9, the magnetic transverse field treatment required to produce a flat hysteresis loop can be carried out directly in the continuous process. The device required for this is shown in FIG. For this purpose, at least part of the passage of the furnace is guided between the pole pieces of a yoke, so that the magnetic cores which pass through are subjected to a homogeneous magnetic field in the axial direction, as a result of which a uniaxial anisotropy transverse to the direction of the wound strip is formed. The field strength of the yoke must be so high that the magnetic cores are at least partially saturated in the axial direction during the heat treatment.

The following results were achieved with this measure

With a field strength of 0.3 T between the pole pieces of the yoke, which was effective along the entire heating section, magnetic cores with the dimensions 21 mm x 11.5 mm x 25 mm with the composition Fet _{) a} ιCu ₁ o ^si 15, 6 ₂ ^B ₆ , ₈₅ ^Nb ₂ , ₉₈ generated that had permeability values of approx. μ = 23,000 (f = 50 Hz). The remanence ratio was reduced to 5.6% due to the axial field effect.

When only half the heating distance was occupied, the uniaxial anisotropy remained weaker and the hysteresis loop became less flat.

In the case of tempering without a magnetic yoke, the remanence ratio was in comparison to or above 50% and the

The permeability curve as a function of the field strength corresponded to that of round hysteresis loops.

With the method and the devices according to the invention, a large-scale production route can be followed by first crystallizing all of the magnetic cores that occur in one pass. Depending on whether the required hysteresis loops should now be round, flat or rectangular, these magnetic cores are then either immediately finished, i. H. encased in a housing, annealed in a longitudinal magnetic field on a rectangular hysteresis loop or in a magnetic transverse field on a flat hysteresis loop and only then finished.

In contrast to the conventional processes, the cores can be manufactured much faster and in a much more economical way.

Claims

claims

1. A method for producing magnetic cores consisting of a soft magnetic iron-based alloy, wherein at least 50% of the alloy structure is taken up by fine crystalline particles with an average particle size of 100 nm or less, with the following steps: a) providing an alloy melt; b) production of an amorphous alloy strip from the alloy melt using rapid solidification technology; c) winding the amorphous tape into amorphous magnetic cores; d) heat treatment of the unstacked amorphous magnetic cores in a pass to nanocrystalline magnetic cores.

2. The method according to claim 1, characterized in that the heat treatment of the unstacked amorphous magnetic cores is carried out on heat sinks which have a high thermal capacity and a high thermal conductivity.

3. The method according to claim 2, characterized in that a metal or a metallic alloy or a metal powder is provided as the material for the heat sinks.

4. The method according to claim 3, characterized in that copper, silver or a heat-conductive steel is provided as metal or as metal powder.

5. The method according to claim 2, characterized in that a ceramic is provided as the material for the heat sinks.

6. The method according to claim 2, characterized in that a ceramic powder is provided as the material for the heat sinks.

7. The method according to claim 5 or 6, characterized in that magnesium oxide, aluminum oxide or aluminum nitride is provided as ceramic or ceramic powder.

8. The method according to any one of claims 1 to 7, characterized in that the heat treatment is carried out in a temperature interval of approximately 450 ° C to approximately 620 ° C.

9. The method according to claim 8, characterized in that a temperature window of 450 ° C to 500 ° C is run through during the heat treatment.

10. The method according to claim 9, characterized in that the temperature window is run through with a heating rate of 0.1 K / min to about 20 K / min.

11. Furnace for performing the method according to one of claims 1 to 10 with A) a furnace housing, the at least one annealing zone and one

Has heat source; B) means for loading the annealing zone with unstacked amorphous magnetic cores;

C) means for conveying the unstacked amorphous magnetic cores through the annealing zone and

D) Means for removing the unstacked heat-treated nanocrystalline magnetic cores from the annealing zone.

12. Oven according to claim 11, characterized in that further are provided

E) Means for applying a protective gas to the annealing zone.

13. Furnace according to claim 11 or 12, characterized in that the furnace housing has the shape of a tower furnace, in which the annealing zone extends vertically.

14. Oven according to claim 13, characterized in that a vertically extending conveyor belt is provided as a means for conveying the unstacked amorphous magnetic cores through the vertically extending annealing zone.

15. Oven according to claim 14, characterized in that the vertical conveyor belt is provided with supports perpendicular to the conveyor belt surface made of a material with high thermal capacity and high thermal conductivity, on which the magnetic cores rest.

16. Oven according to claim 13, characterized in that as means for conveying the unstacked amorphous magnetic cores through the vertically extending annealing zone are supports supported on rollers.

17. Oven according to claim 16, characterized in that the supports consist of a material with a high thermal capacity and high thermal conductivity, on which the magnetic cores rest.

18. Oven according to one of claims 13 to 17, characterized in that the vertically extending annealing zone is divided into several separate heating zones, which are provided with separate heating controls.

19. Furnace according to claim 11 or 12, characterized in that the furnace housing has the shape of a tower furnace, in which the annealing zone runs horizontally.

20th Furnace according to claim 19, so that the horizontally extending annealing zone is divided into several separate heating zones which are provided with separate heating controls.

21. Oven according to one of claims 17 or 18, characterized in that as a means for transporting the unstacked amorphous

Magnetic cores through the horizontally extending annealing zone is provided at least one support plate rotating about the tower furnace axis.

22. Oven according to claim 19, characterized in that the support plate consists entirely or partially of a material with a high thermal capacity and high thermal conductivity, on which the magnetic cores rest.

23. Oven according to one of claims 18 to 20, characterized in that a plurality of support plates stacked one above the other rotating about the tower furnace axis are provided.

24. Furnace according to one of claims 11 or 12, characterized in that the furnace housing has the shape of a horizontal continuous furnace, in which the annealing zone runs horizontally.

25. Oven according to claim 24, characterized in that a conveyor belt is provided as a means for conveying the unstacked amorphous magnetic cores through the horizontally extending annealing zone.

26. Oven according to claim 25, characterized in that the conveyor belt is provided with supports which consist of a material with a high thermal capacity and high thermal conductivity on which the magnetic cores rest.

27. Oven according to claim 13, characterized in that as a means for transporting the unstacked amorphous

Magnetic cores are supported by rollers due to the vertical glow zone.

28. Oven according to claim 27, characterized in that the supports consist of a material with high thermal capacity and high thermal conductivity, on which the magnetic cores rest.

29. Furnace according to one of claims 22 to 23, characterized in that the horizontally extending annealing zone in several separate

Heating zones is divided, which are provided with separate heating controls.

30. Oven according to claim 14, 18 or 24, characterized in that the separate heating zones comprise a first heating zone, a crystallization zone, a second heating zone and a maturing zone.

31. Oven according to one of claims 11 to 30, characterized in that to adjust the uniaxial anisotropy, the pole pieces of a magnetic yoke are at least partially placed over the passage channel comprised by the furnace housing.