JPH0950908A - Pot type ferrite core - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pot type ferrite core which excels in productivity and has an accurate gap dimension. SOLUTION: In a pot type ferrite core 1 which has a middle leg, an external leg disposed so as to surround it and a connection part for connecting them, and the butted surface of the respective legs is formed in a circular arc-like form and the difference G of height between the highest part and the lowest part of the legs is not less than 1μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pot type ferrite core with a gap.

[0002]

2. Description of the Related Art FIG. 7 shows a perspective view of an example of a conventional pot type ferrite core with a gap, and FIG. 8 shows a sectional view thereof. This pot-type ferrite core 104 has a cylindrical middle leg 10
1, and a cylindrical outer leg 102 is formed around it,
On the outer leg 102, a groove 103 for drawing out a lead of the winding is formed. The middle leg 101 is formed shorter than the outer leg 102, and this difference G is called a gap. This gap is formed for the purpose of adjusting the DC superposition characteristic. This pot type ferrite core 10
As shown in FIG. 9, 4 is abutted with another pot-type ferrite core 105 and accommodates a winding inside to form a coil transformer.

In the conventional pot type ferrite core with a gap, a gap must be formed in the middle leg surrounded by the outer leg as shown in FIG. Therefore, a small grindstone that can be inserted into the space inside the outer leg was prepared, this grindstone was inserted into the space of the outer leg, and the gap was processed by the method of grinding only the middle leg to a predetermined size. . Of course, the abutting surface of the outer leg is also polished flat.

[0004]

In this pot type ferrite core with a gap, the gap size has an extremely large effect on the required characteristics. Therefore, it is important to obtain this gap size with high accuracy. However, in the pot-type ferrite core, it is necessary to perform the gap machining one by one, and the mass productivity is low, and in order to obtain a highly accurate gap dimension, it is necessary to spend sufficient man-hours and use an expensive machining machine. Therefore, the cost is high. Heretofore, it was difficult to obtain a pot type ferrite core with a gap that achieves high productivity and low cost. In view of the above, the present invention has high productivity,
An object of the present invention is to provide a pot-type ferrite core that can obtain a highly accurate gap size.

[0005]

DISCLOSURE OF THE INVENTION The present invention relates to a pot type ferrite core having a middle leg, an outer leg arranged so as to cover the periphery thereof, and a connecting portion for connecting them, in which each leg is butted. The pot type ferrite core is characterized in that the surface is formed in an arc shape, and the difference between the highest portion and the lowest portion of the leg portion is 1 μm or more.

[0006]

According to the present invention, the abutting surface of the pot-type ferrite core is formed in an arc shape, the arc surface is formed by virtually continuous surfaces, and the arc surface is recessed, and has a gap. A pot type ferrite core is obtained. According to the core of the present invention, when the shape of the core and the shape of the arc are determined, the gap size is determined. For example, a gap can be formed by one continuous grinding, and a pot type ferrite core with a gap having an extremely high gap size can be obtained.

[0007]

1 is a plan view of a first embodiment according to the present invention, FIG. 2 is a side view in the A direction of FIG. 1, and FIG. 3 is a side view in the B direction of FIG. This embodiment is a pot-type ferrite core 1 having a cylindrical outer leg 2 and a cylindrical middle leg 3, and its abutting surface is formed in an arc shape. This butt surface is
It is formed on an imaginary line 4 having an arc shape. And the outer leg 2
The difference G between the highest part of and the lowest part of the middle leg 3 is the gap,
This G is formed to be 1 μm or more. At this time, a gap portion is also formed on the outer leg 2. Example 1
4 and 5 are schematic views showing an example of the forming means. 4 is a front view and FIG. 5 is a side view. The shaft 6 of the circular cup diamond 5 is arranged at a predetermined angle θ with respect to the extending direction 7 of the legs of the pot-type ferrite core 1, and the cup-diamond is rotated to move the pot-type ferrite core 1 into the cup-diamond 5. On the other hand, the outer leg and the middle leg of the pot type ferrite core 1 are ground at the same time by passing in the C direction or the D direction. In FIG. 4, 8 is an imaginary line of the cup diagram.
As a result, the pot type ferrite core 1 with a gap of Example 1 is easily formed. Also, according to this method,
Since the outer leg and the middle leg are ground at the same time to form the gap, the gap dimension can be accurately formed. Example 1
The core has an outer diameter of 15 mm and a height of 21 m
A pot type ferrite core with a gap having a G dimension of 0.025 mm was formed on the core of m. 200 pieces were manufactured, and the variation in the gap size was ± 2 μm. On the other hand, the variation of the conventional method is ± 25μ.
m. As described above, it was possible to manufacture with a variation of 1/10 or less of the conventional one.

This pot-type ferrite core 1 and an ordinary pot-type ferrite core 10 in which no gap is formed
Butt them as shown in the sectional view of Fig.
1 is stored to form a coil transformer. Further, the lead of the winding may be provided with a lead-out groove as in the conventional case.
Further, the present invention is not limited to the shape of the above embodiment, and may be a square pot type ferrite core, or a through hole may be formed in the middle leg. The present invention
This is effective in a pot type ferrite core with a gap having a gap size of 1 μm or more, but preferably when the gap size is 10 μm or more, more preferably 0.1.
It is a case of mm or less. According to the present invention, it is possible to perform the gap machining while continuously flowing the core, which has conventionally been subjected to the gap machining one by one, and the productivity is good.
In addition, by processing the entire outer leg and the middle leg at the same time by the gap processing, extremely high gap accuracy can be obtained.

[0009]

According to the present invention, a pot type ferrite core with a gap in which the gap dimension is formed with high precision can be obtained with high productivity, which is useful in an inductance component such as a transformer or a choke coil.

[Brief description of drawings]

FIG. 1 is a plan view of a first embodiment according to the present invention.

FIG. 2 is a side view as viewed from a direction A in FIG.

FIG. 3 is a side view seen from the direction B in FIG.

FIG. 4 is a schematic front view of the forming means according to the first embodiment of the present invention.

FIG. 5 is a schematic side view of the forming means according to the first embodiment of the present invention.

FIG. 6 is a cross-sectional view of a usage example of the ferrite core according to the present invention.

FIG. 7 is a perspective view of a conventional example.

FIG. 8 is a sectional view of a conventional example.

FIG. 9 is a cross-sectional view of a usage example of a conventional example.

[Explanation of symbols]

 1 Pot Type Ferrite Core 2 Outer Leg 3 Middle Leg 4 Virtual Line 5 Cup Diamond 6 Axis

Claims (1)

[Claims] 1. A pot-type ferrite core having a middle leg, outer legs arranged to cover the periphery of the middle leg, and a connecting portion for connecting the middle leg to each other, and the abutting surface of each leg is formed in an arc shape. The pot-type ferrite core is characterized in that the difference between the highest part and the lowest part of the legs is 1 μm or more.