JPH04311010A - Manufacture of wound core - Google Patents

Abstract

PURPOSE:To obtain a low-loss wound core having excellent magnetic characteristics using a method wherein an amorphous magnetic thin band is wound and annealed. CONSTITUTION:Two inner molds 12 and 13, consisting of heat-resisting material, a center rod 14, a coil spring 22 and nuts 18 and 18 are set inside an amorphous magnetic thin band 11 which is wound up in coil form independently or lap- wound with a heat-proof insulating film. By the compressive repulsion of a spring 22 generated by the thread movement of the above-mentioned nuts 18, expanding force is given to an amorphous magnetic thin band by adding force to the above-mentioned inner molds 12 and 13 in the direction wherein they are moving away with each other, and an annealing operation is conducted under this condition.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a wound core by winding an amorphous magnetic ribbon into a coil and annealing it.

0002

2. Description of the Related Art Iron core materials for induction electrical equipment such as transformers and reactors are required to have good excitation characteristics and low iron loss. Until now, silicon steel plates and silicon steel strips have generally been used as materials that meet this requirement. These are manufactured through processes such as casting, hot rolling, cold rolling, and annealing.In contrast, in recent years, the above-mentioned Advances have been made in the development of technology that allows the direct production of magnetic ribbons without going through processes such as rolling. The magnetic ribbon manufactured in this manner has an amorphous structure like glass, has no anisotropy, and has high electrical resistance. Therefore, in addition to significantly reducing iron loss, it also has excellent excitation characteristics, so it is expected to be an energy-saving iron core material, and various applications are being considered.

Among the above-mentioned amorphous magnetic ribbons, examples of iron-based ones include ME, which is a trade name of Allied Chemical Co., Ltd.
There are products such as TGLAS2605S2, which are being applied to power distribution transformers, high-frequency power transformers, etc. When manufacturing a wound core using this amorphous magnetic ribbon, first, as shown in FIG. A method is adopted in which the material is wound up, then removed from the winding frame 2, formed into a rectangular shape using an inner mold 3 having a rectangular outer periphery as shown in FIG. 8, and annealed in a magnetic field. Through this annealing, the amorphous magnetic ribbon 1
The internal strain that remained during the rapid solidification of the iron core is removed, the magnetic domains are aligned in a predetermined direction, and the magnetic properties of the iron core are improved. At the same time, plastic deformation occurs in the wound core made of the amorphous magnetic ribbon 1, and after annealing, the rectangular wound core shape can be maintained without any particular external force being applied.

0004

[Problems to be Solved by the Invention] However, when winding and forming the amorphous magnetic ribbon 1 into a coil shape, winding distortion occurs due to poor shape of the ribbon 1 such as changes in thickness in the width direction. It is conceivable that the core may be subjected to distortion or surface pressure due to shape change during molding, or that unexpected force may be applied when handling the wound core. On the other hand, iron-based amorphous magnetic materials as mentioned above have high strain sensitivity and positive magnetostriction characteristics, so when compressive strain occurs in the thickness direction, magnetic properties such as iron loss occur. Characteristics deteriorate. As mentioned above, most of the residual strain in the amorphous magnetic ribbon 1 can be removed by annealing during core forming, but if annealing is performed with the above-mentioned compressive strain still occurring, the magnetic domain structure is fixed in that state, so it acts as a resistance to magnetic flux,
This is because it becomes a cause of greatly worsening iron loss.

[0005] As a method for preventing and improving such a phenomenon, for example, as shown in Japanese Patent Application Laid-Open No. 114205/1983, an inner mold used when forming a wound core is used to form a longitudinal direction in an amorphous magnetic ribbon. A method has been proposed in which annealing is performed with a tension of . However, in general, in such a method, as the temperature rises during annealing, the amorphous magnetic ribbon expands and the tension is relaxed, and after the annealing temperature is reached, the effect of tensile strain can no longer be expected.

Furthermore, the annealing temperature is generally 360 to 4
A temperature in the range of 20° C. is selected, but a higher temperature is desirable for the purpose of eliminating distortion as described above. However, since the recrystallization temperature of an iron-based amorphous magnetic ribbon having a normal composition is in the range of 450 to 600°C, better magnetic properties can be obtained by annealing at a slightly lower temperature. Since the annealing temperature is close to the recrystallization temperature in this way, it is necessary to strictly control the temperature during annealing. If the temperature is outside the optimum temperature, strain relief may become insufficient or recrystallization may occur, resulting in the loss of the excellent magnetic properties unique to amorphous magnetic materials.

On the other hand, since amorphous magnetic ribbons are generally not coated with an insulating coating, the insulation resistance between the core layers is affected in transformer cores with frequencies of 10 kHz or higher.
Increased eddy current loss at high frequencies may become a problem. In particular, in high-voltage reactors such as saturable reactors for high-voltage pulse generation, the voltage per turn of the winding is high, so if the insulation resistance between the core layers is low, the core may be locally heated due to dielectric breakdown, etc. This may occur. Furthermore, in order to obtain a large operating magnetic flux density, high square hysteresis characteristics are required.

[0008] As a method for preventing an increase in eddy current loss in the iron core used in saturable reactors, etc., there is a method disclosed in Japanese Patent Laid-Open No. 6
As shown in Publication No. 3-6822, an iron core is formed by overlapping and winding an amorphous magnetic ribbon and a heat-resistant insulating film with a tape width equal to or greater than the width of the ribbon, and then annealed. A method of forming an iron core by winding an amorphous magnetic ribbon and impregnating it with a synthetic resin after strain relief annealing, as disclosed in Japanese Patent Publication No. 59-79516, has been studied.

However, in the method of layering and winding an amorphous magnetic ribbon and a heat-resistant insulating film and then annealing the core, the interlayer insulation resistance increases and an increase in eddy current loss can be prevented; When the heat-resistant insulating film shrinks due to heat, compressive stress is applied to the amorphous magnetic ribbon, which may impair the low loss and high square hysteresis characteristics inherent to the amorphous magnetic ribbon.

[0010] Furthermore, in the method of winding an amorphous magnetic ribbon to form a wound core and then impregnating it with synthetic resin after annealing to insulate the ribbon layers, the interlayer insulation resistance also increases and the interlayer insulation Although the increase in eddy current loss due to resin impregnation can be prevented, the stress sensitivity of the amorphous magnetic ribbon is large, so even if strain relief annealing is performed after forming the wound core to improve the magnetic properties, the stress caused by resin impregnation will reduce the annealing effect. There was a problem that the desired magnetic properties could not be obtained.

The present invention has been made in view of the above-mentioned circumstances, and therefore, its first object is to improve the influence of compressive strain and temperature control during annealing for forming a wound core using an amorphous magnetic ribbon. An object of the present invention is to provide a method for manufacturing a wound core, which can easily manufacture a wound core with excellent magnetic properties and which can further reduce iron loss by eliminating the strictness of the method.

[0012] A second object of the present invention is to increase the interlayer insulation resistance of a wound core made of amorphous magnetic ribbons, which has further low loss and which can fully exhibit high square hysteresis characteristics. To provide a method for manufacturing iron cores. [Structure of the invention]

[0013]

[Means for Solving the Problems] In order to achieve the above object, the method for manufacturing a wound core of the present invention includes two layers made of a heat-resistant material placed inside an amorphous magnetic ribbon wound into a coil. An inner mold, a center rod extending between the inner molds, a coil spring surrounding this center rod, and a nut that is screwed along the center rod to compress the coil spring are set, and the coil spring is compressed by screwing the nut. The present invention is characterized in that a force is applied to the two inner molds in a direction that causes them to move away from each other due to repulsion, thereby applying an expansion force to the amorphous magnetic ribbon, and annealing is performed in this state.

[0014] Furthermore, the method for manufacturing a wound core of the present invention includes two inner molds made of a heat-resistant material, and two inner molds made of a heat-resistant material on the inside of an amorphous magnetic ribbon wound into a coil shape with a heat-resistant insulating film layered thereon. A center rod that extends between the molds, a coil spring surrounding this center rod, and a nut that is screwed along the center rod and presses the coil spring are set, and the above two items are Another feature is that an expanding force is applied to the amorphous magnetic ribbon by applying a force in a direction that moves the inner mold away from each other, and annealing is performed in this state.

[0015]

[Operation] According to the above means, expansion force is applied to the amorphous magnetic ribbon wound into a coil by the compression and repulsion of the coil spring. Even when expanded, it can continue to provide its expansion force.

[0016] Furthermore, a heat-resistant insulating film is layered on an amorphous magnetic ribbon, and even if the heat-resistant insulating film shrinks due to heat during core annealing, the amorphous magnetic ribbon expands due to the compression and repulsion of the coil spring. Force can be continued to be applied, and compressive stress can be avoided.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

First, FIGS. 1 and 2 show an amorphous magnetic ribbon 11 that has been previously wound into a coil using the winding frame 2 shown in FIG. 12 and 13 are set. The inner molds 12 and 13 are configured to be divided so as to be movable in directions away from each other (horizontal direction in the figure), and both have a rectangular shape.

A center rod 14 is provided between the inner molds 12 and 13, and one end on the right side in the figure is a threaded portion 15.
It is screwed into a screw hole 16 formed in the center of the inner mold 12. On the other hand, the other end of the center rod 14 on the left side in the figure is inserted into a hole 17 formed in the center of the inner mold 13 with an inner diameter larger than the outer diameter of the center rod 14.

A nut 18 is screwed onto the threaded portion 15 of the center rod 14, and a backing plate 19 is fitted into the center of the nut 19 through a hole 20 formed larger than the threaded portion 15. This backing plate 19 is brought into contact with the nut 18 via a washer 21 .

A coil spring 22 is interposed between the backing plate 19 and the inner mold 13 so as to surround the center rod 14. With respect to this coil spring 22, the coil spring 2
Circular recesses 23 and 24 having approximately the same inner diameter as the outer diameter of the coil spring 22 are provided to stably position the end of the coil spring 22.

[0022] Furthermore, these inner molds 12, 13, center rod 14
, nut 18, patch plate 19, washer 21, and coil spring 22 are all heated to approximately 400°C, which is the annealing temperature described later.
The inner molds 12 and 13 are made of heat-resistant materials that can withstand
The coil spring 22 is made of low alloy steel.

[0023] These settings are performed in the following procedure. First, the nut 18 is lightly screwed onto the threaded portion 15 of the center rod 14, and the threaded portion 15 of the center rod 14 in this state is inserted into the inner mold 1.
Insert the screw into the screw hole 16 of No.2. Next, the washer 21, the cover plate 19, the coil spring 22, and the inner mold 13 were sequentially fitted onto the center rod 14 from the other end side of the center rod 14, and the thus assembled product was wound into a circular coil shape. It is placed inside the amorphous magnetic ribbon 11.

After that, by screwing the nut 18 along the threaded portion 15 of the center rod 14, the coil spring 22 is pressed through the washer 21 and the backing plate 19, and the inner mold 13 is moved away from the inner mold 12. move it to And nut 1
By continuing the spiral movement of step 8, the inner molds 12 and 13 will eventually come into sufficient contact with the inner surface of the amorphous magnetic ribbon 11 to form the amorphous magnetic ribbon 11 into a rectangular shape. Along with this, a compressive load acts on the coil spring 22, causing it to deflect. Furthermore, when the nut 18 is continued to be screwed on using a spanner or the like, a sufficient expansion force acts on the amorphous magnetic ribbon 11 due to the repulsive force that increases as the deflection of the coil spring 22 increases. The magnitude of this expansion force can be controlled by the screwing distance of the nut 18.

[0025] In the state set as above, it is then heated to about 400°C in an annealing furnace and then cooled. This fold,
The amorphous magnetic ribbon 11 has a coefficient of linear expansion (7.6×10−
6/°C), but the absolute amount is as small as about 1 mm in the case of a core of normal size, and when the amorphous magnetic ribbon 11 is first set This is approximately one order of magnitude smaller than the amount of compressive deflection given to the coil spring 22 in order to impart this. (In the case of a closely wound coil spring, the spring constant k is expressed by the following formula.

[0026]

[Math 1]

[0027] Here, P is the load, δ is the deflection of the spring, and G
is the spring material rigidity, d is the coil wire diameter, R is the coil radius, n
indicate the number of coil turns, d=30mm, R
=50mm, n=5, G=5380kgf/mm2
, P=5ton

[0028]

[Math 2] becomes. )

Therefore, by selecting an appropriate size for the coil spring 22, it is possible to continuously apply a substantially constant expansion force without being greatly affected by temperature changes, and in particular, it is possible to apply a substantially constant expansion force to the coil spring 22. Even if the amorphous magnetic ribbon 11 expands due to the temperature increase during annealing, the expansion force can be continuously applied. However, as the temperature rises, the rigidity G of the spring material changes. The rigidity G is

[0030]

[Math 3]

(E is the longitudinal elastic modulus, ν is Poisson's ratio), and the temperature change in the longitudinal elastic modulus E of iron-based materials is -0
．． 03%/°C, it is thought that the decrease in rigidity G at 400°C is about 12%, and the magnitude of expansion force P at 400°C is also expected to decrease by about 12%. However, this degree of decrease is not a problem and it recovers again during the cooling process.

[0032] Iron loss after annealing the amorphous magnetic ribbon 11 made of Fe-Si-B alloy at a temperature range of 300°C to 420°C using the inner molds 12 and 13 assembled as described above. The measurement results are shown in Figure 3. The figure shows the conventional method with a magnetic field of 800A/
The results of annealing in a magnetic field excited at m and annealing without a magnetic field are also shown. Results were obtained that were lower than that, and that the difference due to changes in annealing temperature became smaller.

The materials of the inner molds 12 and 13, the center rod 14, the nut 18, the cover plate 19, the washer 21, and the coil spring 22 may be other than the above-mentioned carbon steel or low alloy steel. In addition to cast iron, the inner molds 12 and 13 may be made of mullite-based ceramics, and the coil spring 22
The use of austenitic stainless steel such as SUS304 has the advantage of superior heat resistance and the ability to reduce temperature changes in the spring constant. Next, a second embodiment of the present invention will be described with reference to FIGS. 4 to 6.

In this case, especially in FIGS. 4 and 5,
The same parts as in FIGS. 1 and 2 are given the same reference numerals, and therefore only the parts that are different will be described. First, in FIG. 4, the amorphous magnetic ribbon 11 is stacked with a heat-resistant insulating film 26 on an intermediate roll 25, and cut at one point in the circumferential direction as shown by a cut portion 27, thereby forming a circular roll that can be expanded and contracted. It is wound into a coil shape by the frame 28. The winding frame 28 is overlapped with this heat-resistant insulating film 26.
As shown in FIG. 5, two approximately semicircular inner molds 2 are placed inside the amorphous magnetic ribbon 11 (inside the winding frame 28).
9 and 30 are set, and the center rod 14 is provided between the inner molds 29 and 30, extending in the same manner as described above. other than this,
Nut 18, backing plate 19, washer 21, and coil spring 2
2 is the same as above, and the setting procedure thereof is also the same as above.

However, in this case, the inner molds 29, 30,
The center rod 14, nut 18, backing plate 19, washer 21, and coil spring 22 are made of stainless steel, particularly austenitic stainless steel such as SUS304. In this case, annealing is performed with a magnetizing force of 800
The test is carried out in a DC magnetic field of A/m.

In this way, since the heat-resistant insulating film 26 is layered on the amorphous magnetic ribbon 11, even if the heat-resistant insulating film 26 shrinks during core annealing, the amorphous magnetic ribbon 11
The expansion force can be continuously applied to the coil spring 22 through the expandable and contractible winding frame 28 due to the above-mentioned compressive repulsion of the coil spring 22, and application of compressive stress can be avoided. Further, since a magnetizing force of 800 A/m is applied during core annealing, a synergistic effect between the expansion force and magnetizing force by the coil spring 22 can be obtained.

Using the inner molds 29 and 30 assembled as described above, the amorphous magnetic ribbon 11 (
METGLAS26, the product name of Allied Chemical Co., Ltd.
05S2) and a heat-resistant insulating film 26 (with a thickness of 7.5 μm)
Regarding the iron core wound in layers with Ube Industries' product name UPILEX-S), the temperature of 380℃, 800A
FIG. 6 shows the measurement results of DC hysteresis characteristics after annealing in a DC magnetic field of /m. In this Figure 6, B1 is the magnetizing force 10
is the magnetic flux density at 0 A/m, Br is the residual magnetism,
Hc is the coercive force and ΔB is the operating magnetic flux density.

FIG. 6 also shows the results of annealing under the same conditions using the conventional method. According to the method of the present invention, not only the magnetic flux density B1, residual magnetism Br, and coercive force Hc at a magnetizing force of 100 A/m , squareness ratio, and operating magnetic flux density ΔB, it was recognized that the method exhibited superior characteristics compared to conventional methods.

In this case, the inner molds 29 and 30 are made of the amorphous magnetic ribbon 11 wound over the heat-resistant insulating film 26.
Alternatively, it may be in direct contact with the winding frame 28 instead of through the winding frame 28. In addition, as the material for the inner molds 29, 30, etc., heat-resistant metals other than austenitic stainless steel can also be used in this case, and in particular, ceramics etc. can be used for the inner molds 29, 30. .

[0040]

[Effect of the invention] The present invention is as explained above,
It has the following effects.

According to the method for manufacturing a wound core according to claim 1, two inner molds made of a heat-resistant material are provided inside the amorphous magnetic ribbon wound into a coil, and a center rod extending between the inner molds; A coil spring surrounding this center rod, and a nut that is screwed along the center rod and presses the coil spring are set, and the compression and repulsion of the coil spring due to the screw movement of this nut causes the above-mentioned 2.
By applying force in the direction of moving away from each other to the inner molds, an expanding force is applied to the amorphous magnetic ribbon, and annealing is performed in this state, so that it can be continuously applied throughout the entire heating and cooling process during annealing. Expansion force can be applied to the amorphous magnetic ribbon, and the effect of magnetic domain alignment can be greatly exhibited regardless of expansion or contraction of the amorphous magnetic ribbon, and iron loss can be significantly reduced. , it is possible to improve magnetic properties. Also, in this case,
Since the appropriate temperature range is also widened, temperature management can be facilitated.

According to the method for manufacturing a wound core according to claim 2, two inner molds made of a heat-resistant material are placed inside the amorphous magnetic thin ribbon wound into a coil shape overlapping a heat-resistant insulating film; A center rod extending between the inner molds, a coil spring surrounding this center rod, and a nut that is screwed along the center rod and presses the coil spring are set. By applying force in the direction of moving away from each other to the two inner molds, an expanding force was applied to the amorphous magnetic ribbon, and annealing was performed in this state, so that the heat-resistant insulating film did not shrink during core annealing. Also, it is possible to continue to apply expansion force to the amorphous magnetic ribbon and avoid the application of compressive stress, thereby achieving low loss and fully demonstrating high square hysteresis characteristics. Can be done. Furthermore, since the operating magnetic flux density can be increased and the wound core can be made smaller, the high frequency power supply device can be made smaller and lighter.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the entire apparatus for carrying out the method, showing a first embodiment of the present invention;

[Figure 2] Longitudinal cross-sectional view of the entire device

[Figure 3] Diagram showing the relationship between annealing temperature and iron loss in comparison with the conventional method

FIG. 4 is a side view of a device for winding an amorphous magnetic ribbon in a heat-resistant insulating film layer according to a second embodiment of the present invention.

[Figure 5]
Figure 1 equivalent diagram

[Figure 6] A diagram showing the DC hysteresis characteristics in comparison with the conventional method

[Fig. 7] A perspective view of a winding device for carrying out the conventional method.

[Fig. 8] Perspective view of molding device

[Explanation of symbols]

11 is an amorphous magnetic ribbon, 12 and 13 are inner molds, 14 is a center rod, 18 is a nut, 22 is a coil spring, 26 is a heat-resistant insulating film, and 29 and 30 are inner molds.

Claims (2)

[Claims] 1. Inside an amorphous magnetic ribbon wound into a coil, two inner molds made of a heat-resistant material, a center rod extending between the inner molds, and a coil spring surrounding the center rod,
In addition, a nut is set that is screwed along the center rod and presses the coil spring, and the compression and repulsion of the coil spring due to the screwing of this nut applies a force in the direction of moving the two inner molds away from each other, forming an amorphous magnetic material. A method for manufacturing a wound iron core characterized by applying expansion force to the ribbon and annealing it in this state. [Claim 2] Inside the amorphous magnetic thin ribbon wound into a coil shape with a heat-resistant insulating film, a layer made of a heat-resistant material is placed.
A set of inner molds, a center rod extending between the inner molds, a coil spring surrounding the center rod, and a nut that is screwed along the center rod and presses the coil spring, and the coil spring is released by screwing the nut. A wound iron core characterized in that a force is applied to the two inner molds in a direction to move them away from each other due to compressive repulsion, thereby applying an expansion force to the amorphous magnetic ribbon, and annealing is performed in this state. Method.