JP2952716B2 - Heat treatment method of magnetic core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a method of manufacturing a magnetic core having excellent magnetic permeability, which is used for a core of a noise filter for normal mode, a high frequency transformer, an active filter, etc. And effective technology.

[0002]

2. Description of the Related Art In the prior art, a thin metal ribbon (magnetic ribbon) made of an amorphous alloy is processed into a slit shape, wound a predetermined number of times, and heat-treated (annealed). An adhesive is impregnated and solidified, and then a gap (void) for cutting a part of a magnetic path is provided to realize the above-mentioned permeability. In addition, a method for obtaining a target constant magnetic permeability only by heat treatment without providing a gap has been known.

[0003] The permanent magnetic permeability greatly depends on the annealing in the manufacturing process of the magnetic core, that is, the heat treatment temperature condition.
In order to obtain stable magnetic permeability, it was necessary to strictly control the heat treatment temperature conditions.

[0004]

However, it has been known that even if the heat treatment conditions are strictly controlled, it is not always possible to obtain a magnetic core having the desired constant magnetic permeability.

The present inventor has found that this is caused by variations in the characteristics of the magnetic ribbon provided as a material, ie, variations in the composition.

FIG. 1 shows the relationship between the heat treatment temperature and the magnetic permeability for 14 samples (R1 to R14) arbitrarily extracted from each material lot of the magnetic ribbon. The heat treatment conditions in the figure are in the air, and the heat treatment time is 2 hours.

The magnetic permeability was measured using a precision LCR meter HP4284A and 42841A, manufactured by Hewlett-Packard Co., Ltd., with an alternating magnetic field of 100 kHz and 5 mOe.
The measurement was performed under the condition of a DC magnetic field of 0 Oe.

The relationship between the magnetic permeability and the constant magnetic permeability has a relationship as shown in FIG. 2. By measuring the magnetic permeability at a DC magnetic field of 0 Oe, the magnetic permeability when a DC magnetic field is superimposed, ie, the constant magnetic permeability, is measured. The permeability can be inferred.

Therefore, it is necessary to lower the magnetic permeability in a state where no magnetic field is applied (0 Oe) to obtain a constant permeability.

By the way, according to FIG.
When the heat treatment is performed at a temperature of 2 ° C. for 2 hours, a magnetic permeability in the range of 180 to 380 around 250 occurs simultaneously. That is, even if the temperature conditions are strictly controlled, the obtained magnetic core may have a difference of at most 200 in the magnetic permeability, and the yield may be extremely deteriorated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to focus on the fact that magnetic ribbons provided in a material lot have variations in characteristics. An object is to constantly obtain a magnetic core having stable product characteristics.

[0012]

Means for Solving the Problems The present invention, in the heat treatment of the magnetic core, and measuring the Curie temperature (Curie point) of the magnetic ribbon is optionally sampled from Filling lot, this
Apply the measured Curie temperature to the relationship between the Curie temperature value and the heat treatment temperature at the target permeability previously created
In this case, the correction value of the heat treatment temperature is determined.
Here, Curie temperature is the temperature of ferromagnetic material
The temperature at which the transition from the ferromagnetic state to the paramagnetic state occurs
(Iwanami Dictionary of Physical and Chemical Sciences)
Shop, "Material Dictionary" Asakura Shoten, "Chemical Dictionary" jointly launched
Edition etc.). Before and after this Curie temperature, the specific heat of the substance is not
Because it is continuous, the measurement method is from ferromagnetic to paramagnetic.
Rather than measuring the temperature of whether the transition to the
Changes in temperature, resulting from changes in the specific heat of the sample
DSC (Di-
fferential Scanning Calorimetry: Differential scanning calorimetry
It is widely known to use devices.

[0013]

In the above means, the magnetic core body to be subjected to the heat treatment may be, for example, a magnetic ribbon made of an amorphous metal processed into a slit shape and wound.

The amorphous metal used in the present invention is an Fe-based amorphous alloy (metal) in which the content of Fe in the alloy is 50 atomic% or more. -BC, Fe-
B-Si, Fe-B-Si-C, Fe-B-Si-C
Fe-based materials such as r, Fe-Co-B-Si and Fe-Ni-Mo-B can be exemplified. Among them, Fe is particularly preferable.
The base amorphous _{metal, Fe X Si Y B Z M} W can be exemplified. Here, X = 50-85, Y = 5-15, Z =
5 to 25 (X, Y, and Z each represent atomic%), M is Co, Ni, Nb, Ta, Mo, W, Zr, Cu, C
A metal composed of one or a combination of two or more of r, Mn, Al, P, etc., wherein _W = 0 to 5 atomic%.

The atmosphere of the heat treatment may be the same as that of the air. Preferably, an inert atmosphere such as a nitrogen atmosphere is used to remove the Kapton tape used for stopping the end of the amorphous ribbon. It can also be prevented.

In the heat treatment, a wet atmosphere may be used as a treatment condition. In this case, the magnetic core body is heat-treated in a humid atmosphere having a unit water vapor content of ³ to 600 g / m ³ , particularly preferably 20 to 200 g / m ³ in terms of 25 ° C., so as to reduce the magnetic permeability of the core in a relatively low temperature region. It is possible to obtain a stable constant magnetic permeability over a wide temperature range.

In the present invention, first, a magnetic ribbon is arbitrarily extracted from a material lot before heat treatment, a part of the magnetic ribbon is cut out, and this is used as a sample to obtain a DSC (Differential Sca).
The Curing temperature (Curie point) is measured using an nning calorimetry (differential scanning calorimetry) device.

FIG. 3 shows the change in the differential calorie measured by using a DSC device by weighing a magnetic ribbon as a 20 mg sample. From the figure, the Curie temperature (T
c) is 407 ° C.

Next, the relational expression between the heat treatment temperature and the Curie temperature at the previously measured target magnetic permeability is expressed by the above-mentioned DS.
The heat treatment control temperature is determined by substituting the measured temperature value from the C apparatus.

The above relational expression can be derived, for example, as follows. Such a relational expression can be obtained, for example, by sampling the relationship between the heat treatment temperature and the Curie temperature at the target magnetic permeability with a plurality of lot materials in advance.

FIG. 4 shows the change of the heat treatment temperature with respect to the Curie temperature at the magnetic permeability 250, and FIG. 5 shows the change of the heat treatment temperature with the Curie temperature at the magnetic permeability 300.

As shown in both figures, it has been found that there is a strong positive correlation between the Curie temperature and the heat treatment temperature, from which the following equation is derived by the least square method.

[0023]

T (° C.) = 1.634 × Tc (° C.) − 204.77

[0024]

T (° C.) = 1.363 × Tc (° C.) − 99.88 In Equation 1, T is a heat treatment control temperature at which a target magnetic permeability (for example, 250) is obtained, and Tc is obtained from the DSC apparatus. Curie temperature and the correlation coefficient is 0.983.

Specifically, the heat treatment temperature is controlled by, for example, stepwise controlling the electric furnace in the range of 440 ° C. to 460 ° C. by about 1 ° C. based on the heat treatment control temperature (T) obtained for each material lot. Can be considered.

As described above, the temperature control of the electric furnace is performed based on the heat treatment control temperature (T) determined in Equation 1, and the optimum heat treatment control temperature (T) for obtaining the target magnetic permeability for each predetermined material lot. A heat treatment (annealing) by T) is performed.

[0027]

Embodiment 1 An embodiment of the present invention will be described below.

Allied amorphous ribbon (product name: Metglas 2605S-2: Fe ₇₈ B ₁₃ Si ₉₎
(Atomic%), a thickness of 21 μm, and a width of 10 mm) to obtain a toroidal magnetic core body having an outer diameter of 25 mm and an inner diameter of 15 mm.

On the other hand, the Curie temperature (Tc) of a sample arbitrarily extracted from each product lot of the amorphous ribbon was measured using a DSC device.

Next, the heat treatment control temperature (T) was determined by substituting the measured values into the above equation (1), and the electric furnace was controlled based on the temperature.

At this time, in this embodiment, the Curie temperature (T
c) The heat treatment temperature (T) of the electric furnace was controlled at 444 ° C. for the lot material having a temperature of 397.1 ° C.

The heat treatment atmosphere was a nitrogen gas atmosphere, and the heat treatment time was 2 hours. As a result, a target having a yield of 97% was obtained in the range of 245 to 255 with respect to the target magnetic permeability of 250.

After the completion of the heat treatment, the magnetic core body was housed in a case made of synthetic resin without providing a gap to form a magnetic core.

[0034]

Embodiment 2 The same amorphous ribbon as Allied (Metglas 2605S-2:
Fe ₇₈ -B ₁₃ -Si ₉ , thickness 21 μm, width 10 mm) was wound to obtain a toroidal magnetic core body having an outer diameter of 25 mm and an inner diameter of 15 mm.

On the other hand, the Curie temperature (Tc) of a sample arbitrarily extracted from each product lot of the amorphous ribbon was measured using a DSC device.

Next, the heat treatment control temperature (T) was determined by substituting the measured value into the above-mentioned equation (1), and the electric furnace was controlled based on the temperature.

At this time, in this embodiment, the Curie temperature (T
c) The heat treatment temperature (T) of the electric furnace was controlled at 446 ° C. for the lot material having the temperature of 400.4 ° C.

The heat treatment atmosphere was a nitrogen gas atmosphere, and the heat treatment time was 2 hours. As a result, a target magnetic permeability of 290 to 300 with respect to the target magnetic permeability of 300 was obtained at a yield of 94%.

After the completion of the heat treatment, the magnetic core body was housed in a case made of a synthetic resin without providing a gap to form a magnetic core.

[0040]

According to the present invention, a magnetic core having stable product characteristics can be constantly obtained even when the magnetic ribbon provided as a raw material before the heat treatment has a variation.

[Brief description of the drawings]

FIG. 1 is a graph showing a variation between a heat treatment temperature and a magnetic permeability for each lot of a magnetic ribbon.

FIG. 2 is a graph showing a change in magnetic permeability of a magnetic ribbon with respect to a DC superimposed magnetic field.

FIG. 3 is a graph showing a change in working calorie measured using a DSC device in the example.

FIG. 4 is a graph showing a change in heat treatment temperature with respect to a Curie temperature at a magnetic permeability of 250;

FIG. 5 is a graph showing a change in heat treatment temperature with respect to a Curie temperature at a magnetic permeability of 300;

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaru Yoshimura 580-32 Takuji, Nagaura, Sodegaura-cho, Kimitsu-gun, Chiba Pref. Mitsui Petrochemical Industries Co., Ltd. (58) Field surveyed (Int.Cl. ⁶ , DB name) ) H01F 1 / 153,41 / 02 C21D 6 / 00,8 / 12 C22F 1 / 00,1 / 10

Claims (1)

(57) [Claims] When a heat treatment is performed after winding a magnetic ribbon, a Curie temperature of a magnetic ribbon arbitrarily sampled from a material lot is measured, and the Curie temperature is compared with a Curie temperature value at a target permeability previously prepared. A heat treatment method for a magnetic core, wherein a correction value of the heat treatment temperature is determined by applying the correction value to a relationship with the heat treatment temperature.