JPH0666209B2 - Method of manufacturing magnetic core - Google Patents

Description

The present invention relates to a method for manufacturing a magnetic core, and more particularly to a gap formed by laminating and winding magnetic thin plates and penetrating in the laminating direction. The present invention relates to a method for manufacturing a magnetic core having.

(Prior Art) In an output choke coil or the like in a switching power supply, as shown in FIG. 4, magnetic thin plates made of amorphous alloy or the like are laminated and wound, and a magnetic core 1 having a gap 2 penetrating in the laminating direction is formed. Is used. Such a magnetic core is usually manufactured by a process of laminating and winding magnetic thin plates, impregnating a resin between layers, and then forming a gap.

(Problems to be Solved by the Invention) In the above-described conventional magnetic core, when used in a state in which a current is periodically turned on and off, for example, like an output choke coil in a switching power supply, the switching frequency is a few. In the case of an audible frequency such as KHz, there has been a problem that the core vibrates and produces annoying noise.

The present inventors have examined the above-described noise generation mechanism. As a result, the magnetic field applied to the core through the coil causes expansion and contraction (magnetostriction) of the core in the magnetic path direction. It was clarified that exchanging vibrations in the stacking direction at the free gap part is the cause of noise generation.

The present invention has been made to solve such a conventional problem, and provides a method for manufacturing a magnetic core that causes less unpleasant noise even when the current of a coil is turned on and off at an audible frequency. The purpose is to do.

[Structure of the Invention] (Means for Solving Problems) In the present invention, a resin is impregnated between layers of a magnetic core formed by winding magnetic thin plates in a stack to form a gap penetrating in the stacking direction. It is characterized in that a portion near the gap of the magnetic core is fixed.

Here, as a method of fixing the portion near the gap of the magnetic core, it is effective to impregnate the layers of the magnetic core with resin again.

Other methods of fixing the magnetic core near the gap include a method of applying an adhesive to the vicinity of the gap, or a method of sandwiching the vicinity of the gap with non-magnetic fixing members from both sides in the laminating direction of the magnetic thin plates. To be

(Function) After a resin is impregnated between layers of a magnetic core formed by laminating and winding magnetic thin plates, a gap penetrating in the laminating direction is formed, and the resin between layers in the vicinity of the gap is peeled off. Although the thin plate is in a free state and easily vibrates, if the portion near the gap of the magnetic core is forcibly fixed according to the present invention, the magnetic field applied to the core causes expansion and contraction of the core in the magnetic path direction. Even in this case, vibration in the stacking direction is suppressed in the gap portion of the magnetic thin plates that causes noise generation.

(Embodiment) A method of manufacturing a magnetic core according to an embodiment of the present invention will be described with reference to FIG. First, as shown in FIG. 1 (a), magnetic thin plates 11 made of an amorphous alloy or the like are stacked, wound in a toroidal shape as shown in FIG. 4, and then impregnated with resin. The resin impregnation is a method of impregnating the resin into the gap by using a negative pressure. Through this step, as shown in FIG.
2 is uniformly impregnated.

Next, as shown in FIG. 1B, a gap 13 penetrating in the laminating direction of the magnetic thin plates 11 is formed. Gap 1
The formation of 3 may be performed using, for example, a suitable cutter. Here, looking at the state after the gap 13 is formed, the impregnated resin 12 is peeled off and dropped between the layers of the magnetic thin plate 11 in the vicinity of the gap 13 as shown by 14 in FIG. 1 (b). ing.

Next, as shown in FIG. 1C, a spacer 15 made of a thin non-magnetic material plate is inserted into the gap 13 and the adhesive 1
Fix with 6. The conventional manufacturing process of the magnetic core is up to the process of FIG. 1C, but in this embodiment, resin impregnation is performed again. As a result of this second resin impregnation, the first
As shown in FIG. 1 (d), the resin is impregnated in the falling portion 14 of the resin 12 in FIGS. 1 (b) and (c).
A portion of the magnetic thin plate 11 near the gap 13 is firmly fixed in the stacking direction of the magnetic thin plates 11.

Therefore, when the coil wound around the magnetic core is intermittently energized, even if the core expands or contracts in the magnetic path direction due to the application of the magnetic field, the vibration of the magnetic thin plate 11 in the vicinity of the gap 13 accompanied by the expansion and contraction occurs. Is effectively suppressed and the noise generation is significantly reduced. According to the experiment, the noise generated by the magnetic core based on the conventional technique in which the resin impregnation was performed only once was about 70 dB, whereas the resin impregnation was performed again after the formation of the gap 13 described above. The magnitude of the noise generated by the magnetic core according to the present invention was greatly reduced to about 45 dB under the same operating conditions.

In the above-described embodiment, after the gap is formed, resin impregnation is performed again to fix the portion near the gap of the core, but as another embodiment, as shown in FIG. Adhesive 18 (for example, resin-based adhesive) separate from adhesive 16 for fixing 15
May be applied.

Further, as another embodiment, as shown in FIG. 3, the vicinity of the gap of the core may be sandwiched by plate-like fixing members 19 made of a non-magnetic material such as aluminum from both sides in the laminating direction of the magnetic thin plates. Good.

In any of these embodiments, the noise reduction effect similar to that of the above embodiments can be obtained. The present invention can be variously modified and implemented without departing from the scope of the invention.

[Effects of the Invention] According to the method of manufacturing a magnetic core according to the present invention, a magnetic core with less noise is obtained even when used in a switching power supply or the like in which the current of a coil is turned on and off at an audible frequency. be able to.

[Brief description of drawings]

1 (a) to 1 (d) are process drawings for explaining a method of manufacturing a magnetic core according to an embodiment of the present invention, and FIG. 2 (a).
(B) is a plan view for explaining another embodiment of the present invention and an enlarged view of a portion near the gap. FIG. 3 is a plan view for explaining another embodiment of the present invention and a gap. FIG. 4 is an enlarged view of the vicinity thereof, and FIG. 4 is a plan view for explaining the magnetic core targeted by the present invention. 1 ... Magnetic core, 2 ... Gap, 11 ... Magnetic thin plate, 12
… Resin, 13… Gap, 14… Resin dropout part, 15…
Spacer, 16 ... Adhesive, 17 ... Resin, 18 ... Adhesive,
19 ... A fixing member.

Claims (4)

[Claims] 1. A magnetic core, which is obtained by laminating and winding magnetic thin plates, is impregnated with resin between layers to form a gap penetrating in the laminating direction, and then a portion near the gap of the magnetic core is fixed. Of manufacturing a magnetic core. 2. The method for producing a magnetic core according to claim 1, wherein a resin is again impregnated between layers of the magnetic core in order to fix a portion near the gap of the magnetic core. 3. The method for producing a magnetic core according to claim 1, wherein an adhesive is applied to the gap vicinity portion in order to fix the gap vicinity portion of the magnetic core. 4. In order to fix a portion near the gap of the magnetic core, the portion near the gap is sandwiched by non-magnetic fixing members from both sides in the stacking direction of the magnetic thin plates. A method of manufacturing a magnetic core according to the item.