JPS61248507A - Method for improvement in magnetic properties of amorphous alloy stacked core - Google Patents

Abstract

PURPOSE:To reduce the iron loss of the titled iron core by a method wherein a local dissolution treatment is performed on the corner part of the stacked iron core consisting of the Fe radical amorphous alloy thin plate having the prescribed thickness and on the surface of the thin plate other than the T-type junction part of the stacked iron case of a three-phase transformer, there by enabling to enhance the effect of introduction of local distortion. CONSTITUTION:A local dissolution treatment is performed on the corner part of the stacked iron core consisting of an Fe radical amorphous alloy thin plate of 50mum or more in thickness and on the thin plate other than the T-type junction part of the stacked iron core of a three-phase transformer by projecting a YAG laser beam and the like. As a result, the magnetic domain of a dissolution-treated part is fractionized, a magnetic wall is arranged in the direction of magnetic flux, and amorphous isotropy is left on the corner part and the T-shaped junction part, thereby enabling to reduce the iron loss.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for improving the magnetic properties of stacked iron cores made of amorphous alloys used primarily in power converters such as cadence transformers and high-frequency transformers.

(Prior Art) Amorphous alloy thin plates or strips produced by rapid solidification from a molten state exhibit various excellent properties and are attracting attention for their applications. Among these, Fe-based amorphous alloys have high saturation magnetic flux density and low iron loss, and are therefore being used as materials for various iron cores such as power distribution transformers.

As mentioned above, amorphous metals are inherently low core loss materials, but methods have also been proposed to roughly improve core loss.

The first possible method for reducing iron loss is to apply the method conventionally used for grain-oriented silicon steel sheets. For example, the scratch method. This uses a sharp tip made of hard material to score the surface of a silicon steel plate, dividing the magnetic domains into smaller pieces and reducing iron loss.

Additionally, a local crystallization method has been proposed as another method. This is a method disclosed in Japanese Unexamined Patent Publication No. 57-97808, in which crystallized regions are formed in the form of lines or dots in the width direction of a thin plate. Here, the crystallization method employs irradiation with laser light or electron beam, or heating with electricity while bringing either a metal needle or a metal edge close to or in contact with the surface of the thin plate.

By the way, even when the above-mentioned scratch method was applied to an amorphous alloy thin plate, good results were not necessarily obtained. For example, Narita et al.
h International Conference
e on RapidlyQuenched Meta
ls (1982) P 1001NP 1004 reports the effect of linear strain introduced by annealing an Fe-based amorphous alloy thin plate and then scribing the surface of the thin plate with a diamond needle on iron loss. According to this, the effect of distortion is 5
Iron loss appears in a high frequency range of kHz or more, but it actually increases in a low frequency range of 100 Hz or less, which is important for electric cast lances and the like. The reason for this is that in amorphous alloys, which are thinner than silicon steel sheets, the eddy current loss is originally small in the low frequency range, so the effect of reducing iron loss by magnetic domain refinement is small, and on the contrary, the hysteresis loss increases. This is presumed to be because the total iron loss increases.

Further, the method of introducing local crystallized regions disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 57-97F108 is an effective means for subdividing magnetic domains. However, there is a drawback that it does not necessarily show a certain effect on reducing iron loss in a low frequency range. That is, this publication states that the effect is exhibited at commercial frequencies. However, according to the paper by Narita et al., although the effective range extends to the low frequency side compared to the scratch method, it is ineffective or rather deteriorates below 200 Hz.

As described above, all the methods conventionally attempted to improve the core loss of amorphous alloys, particularly Fe-based amorphous alloy thin plates, have often been ineffective in commercial frequency bands.

The present inventors have already proposed a method described in Japanese Patent Application No. 59-89347 as a method that has a large iron loss reduction effect in a low frequency band. The method involves melting the surface of an amorphous alloy thin plate locally and instantaneously, and then rapidly solidifying it to make it amorphous again.The introduction mode of the zero local melting part is illustrated in Figure 3. It is like a series of parallel lines or dots. As shown in FIG. 3, the direction of the lines and dots is best in the width direction of the ribbon, and an inclination within about 30° is permissible.

Also, the average interval of lines or dots is 1 to 1 for commercial frequencies.
It was to be 20 mm. - Further details regarding the specific means for introducing the local dissolution part and the form of the dissolution part are also disclosed in Japanese Patent Application No. 59-14858 by the present inventors.
It is stated in No. 9.

According to this report, the means for locally melting the surface of an amorphous alloy ribbon is to use a laser beam focused to a beam diameter of 0.5 mmφ or less, preferably a beam diameter of 0.3 + sraφ or less, and with a high energy per single pulse. Density is 0.02-1. OJ/mm
It irradiates with a pulse laser of 2.

The ribbon irradiated with a laser under these irradiation conditions is usually formed into a wound core and then subjected to heat treatment. Amorphous alloys are thin, with a plate thickness of 20 to 30 μm, so the core shape is mostly limited to wound cores.The thin ribbon used in the case of zero-wound cores is difficult to irradiate with the laser over the entire length. Common.

However, recently it has become possible to manufacture thick materials with a thickness exceeding 50 μm and even up to 100 μm, and the application of amorphous materials to laminated iron cores has been considered.

Even in the case of stacked iron cores, it is possible to reduce iron loss by introducing local strain through local melting.
A block of 40 old lengths is shown to l-1.

(Problems to be Solved by the Invention) Although it is an effective means to use an amorphous material in the laminated core as described above, when laminated, the characteristics deteriorate compared to the measured values of a single plate. was recognized. In other words, it was recognized that the space factor (building factor) was large.

The present invention aims to provide a method of increasing the effect of introducing local strain in a stacked core compared to the conventional method and significantly reducing iron loss.

(Means for Solving the Problems) The method of the present invention is such that when a Fe-based amorphous alloy with a plate thickness of 50 μm or more is constructed into a laminated iron core, spaces are placed in the direction of magnetic flux, and Strain is introduced locally by locally and instantaneously melting the amorphous alloy thin plate along a line extending with an inclination of ~120°, and then rapidly solidifying it. Note that the melting zone and the surrounding zone must maintain a substantially amorphous state.

The shape and distribution of the introduced local melting portions are linear or dotted in parallel in the width direction in the leg and yoke portions of a single-phase transformer core, as illustrated in FIG. 1(a). , the corner portions are left without local dissolution treatment.

In addition, in the three-phase transformer core, local melting parts are introduced in the leg parts and yoke parts under the same conditions as in the case of the single-phase transformer core, but in the corner parts and the parts corresponding to the T-shaped wave combination part. It is preferable to leave the local dissolution treatment as is, as illustrated in FIG. 2(a).

The area and depth of the lateral melting parts are determined on the condition that the melting parts and the surrounding parts do not crystallize during heating or during the resolidification process after melting.

The parameters to be controlled include irradiation intensity, beam diameter, sweep speed, and frequency (in the case of pulse mode).

The line width of the melted part is preferably 0.3 mm or less, and in the case of a dot array, the diameter of one spot is preferably 0.51 layers or less. Exceeding these ranges may cause crystallization, and improved magnetic properties are also observed. I won't be able to do it.

The direction of the line or dot array of the locally melted part to be introduced is preferably perpendicular to the magnetic flux direction R of the thin plate l, as shown in Fig. It may be in a tilted direction.

Adjacent lines or series of dots do not need to be parallel or straight; the average inclination angle with respect to the perpendicular direction is less than or equal to a predetermined value, and the average interval d between adjacent lines or series of dots is within a predetermined range. If it is within the range, it will be effective in reducing iron loss.
Therefore, the scope of the present invention also includes a dissolving portion introduced along the sinusoidal curve shown in FIG. The average interval d of lines or dots showing the effect on commercial frequencies is 1 to 20 m.
m, the average angle with respect to the above-mentioned perpendicular direction is preferably 30° or less.

In the present invention, the timing of introducing the local melting zone may be before, during, or after the step of heat treating the amorphous alloy thin plate l.However, the optimum conditions vary depending on the time of introducing the melting zone.For example, YAG laser When a local dissolution part is introduced in the width direction using the pulse mode, the diameter of the effective dissolution part varies depending on the time of introduction, as shown in FIGS. 5 and 6. That is, when introduced after heat treatment, the optimum spot diameter is 50 to 100 μm, but when introduced before heat treatment, the most effective spot diameter is around 200 to 250 μm. The reason for this is thought to be that the effect of introducing the melted zone is alleviated by heat treatment. Differences in effectiveness depending on the timing of introduction also appear in excitation characteristics.

Those introduced after heat treatment showed a decrease in magnetic flux density of several 2 to 1 oz in the magnetic field 10e, whereas those introduced before heat treatment showed almost no decrease in magnetic flux density.

In order to locally melt the surface of the amorphous alloy thin plate, the best way to rapidly heat it is to irradiate it with a narrowly focused laser beam for a short period of time, as described above. If melting is attempted by methods such as electron beam irradiation, contact with high-temperature objects, or localized electrical current, which are otherwise ineffective or even have negative effects, the thermal effect will spread due to the small incident energy density. This is not preferred because crystallization occurs.

The iron loss improvement effect when applying the present invention depends on the thickness of the material, and as shown in Figure 7, the larger the plate thickness, the greater the improvement effect (0 mark in the figure is before irradiation, ・ mark is after irradiation) , plate thickness 80
While μ-kaku shows an iron loss reduction effect of 40 to 50,
When the thickness is 304 g or less, it is about 10 to 20%. The reason for this is that the magnetic domain width of amorphous alloys generally increases as the sheet thickness increases, and the absolute value of abnormal eddy current loss and its proportion to the total iron loss increase. It was verified by observation using a scanning electron microscope that the magnetic domain width is subdivided into regions when the plate thickness is 80 us.

In the present invention, whether or not the portion irradiated with the laser beam has once melted and then resolidified can be clearly distinguished by observing the irradiated portion with an optical microscope or a scanning electron microscope. When irradiated with pulses, the center of the melted part becomes a depression, and the periphery becomes slightly raised. This is thought to be because the alloy melted by the rapid incidence of thermal energy overflows into the surrounding area.

In addition, in the present invention, the area locally melted and resolidified by laser irradiation and the surrounding area are not crystallized. This was confirmed by diffraction, transmission electron microscopy, optical microscopy, etc.

Further, the method of the present invention exhibits similar effects even when applied before or after applying insulation or targeted surface treatment to the surface of a thin plate.

(Function) In this invention, when amorphous alloy thin plates are formed into a stacked iron core, the surfaces of the thin plates except for the corners and T-shaped corrugations are locally and instantaneously melted, and then rapidly solidified. It becomes amorphous again.

At this time, the local dissolution treatment is 6o-120 in the magnetic flux direction.
This is carried out along a line extending with an inclination of By leaving the T-shaped corrugated portion in an amorphous isotropic state without performing melting treatment, an increase in iron loss can be prevented.Therefore, the iron loss of the entire core can be advantageously reduced.

(Example) Next, an example will be given and explained.

Example 1 Compositions Fe5o, 5si6. produced by a single roll method.
A local melting zone was introduced into the free surface of an as-cast amorphous alloy thin plate of 5B+ 2CI, thickness 75 μm, width 50 layers, using a YAG laser, and then N2 was heated at 380°C for 60 minutes.
An experiment was conducted to compare the magnetic properties of a thin plate annealed in a gas atmosphere with a single-phase laminated core. The laser irradiation conditions were a pulse mode with a frequency of 400 Hz, a beam diameter of 0.15 mm, and a power of 5111. Sweep speed 10cII/
sec, the form of the irradiation part is as shown in Figure 3 (b) in the case of a single plate, where the entire surface of the plate consists of a row of dots parallel to the width direction and spaced at 5 mm intervals, and in the case of a stacked core, as shown in Figure 1 (a). As shown in Figure 2(b), there is a stack of boards in which locally melted parts are introduced in the legs and yoke parts except for the corners (the present invention) under the same conditions as the veneer, and as shown in Figure 2 (b), there is a stack of boards with locally melted parts introduced in the legs and yoke parts under the same conditions as the veneer. The magnetic properties of a stack of plates in which the compound was introduced (comparative example) were measured and compared.

However, in both cases, the end layer method is one-layer stacking. Table 1 shows the measurement results of magnetic properties.

As is clear from Table 1, it can be seen that the laminated cores treated by the method of the present invention have lower core loss and therefore lower building factor than the comparative example, and have superior characteristics when laminated.

Table 1 The iron loss is 50Hz, and the iron loss building factor at 1.3 tesla is (me core iron loss)/(single plate iron loss) Example 2 Amorphous alloy of the same lot used in Example 1 An experiment was conducted to compare the characteristics of three-phase laminated cores using thin plates. The mode of irradiation was as shown in FIG. 2(a)-(present invention) and FIG. 2(b)-(comparative example), and the irradiation conditions were the same as those of Example 1.

Table 2 shows the measurement results of each magnetic property.

As is clear from Table 2, it can be seen that the three-phase laminated core treated by the method of the present invention has a smaller core loss and thus a building factor than the comparative example, and has excellent characteristics when laminated.

Table 2 (Effects of the Invention) As explained above, by following the method of the present invention, it is possible to minimize the deterioration of iron loss and increase efficiency when stacking amorphous alloy thin plates into a core. become.

[Brief explanation of drawings]

Figures 1(a) and 2(a) are explanatory diagrams showing a single-phase transformer core and a three-phase transformer core to which the method of the present invention is applied, and Figures 1(b) and 2(b) are explanatory diagrams showing comparative examples of single-phase and three-phase transformer cores, respectively; FIGS. 3 and 4 are explanatory diagrams illustrating the introduction form of local melting parts;
6 and 6 are diagrams showing the relationship between the diameter of the melted part to be introduced and iron loss, however, FIG. 5 shows the case where the melted part is introduced after heat treatment, and FIG. 6 shows the case where it is introduced before heat treatment. 7th
The figure shows the relationship between the thickness and iron loss of an amorphous alloy thin plate. White circles indicate properties without dissolution treatment, and black circles indicate properties after treatment.

Claims (1)

[Claims] When a stacked iron core is composed of Fe-based amorphous alloy thin plates with a plate thickness of 50 μm or more, the surface of the thin plate in the parts other than the corner parts of the stacked iron core and the parts that constitute the T-shaped joint of the three-phase transformer stacked iron core. A method for improving the magnetism of an amorphous alloy laminated iron core, characterized by subjecting it to local melting treatment.