JPH0435008A - Squarish eight-shaped ferrite core - Google Patents

Abstract

PURPOSE:To reduce the size of an outer diameter and to inexpensively manufacture with a simple facility by disposing the lower surfaces of a central leg, a side leg and a yoke on the same surface, and continuously constructing from the upper surface of the central leg to the axial extension part of the central leg of the upper surface of the yoke to be lower than the upper surface of the side leg. CONSTITUTION:A pair of side legs 12a, 12a are so disposed oppositely as to hold a central leg 11a, and both end sides of these magnetic legs are coupled to one another by a yoke 14a. Further, the lower surfaces of the legs 11a, 12a and the yoke 14a are disposed on the same surface 16a, and continuously constructed from the upper surface 17a of the central leg to the axial extension part of the leg 11a of the upper surface of the yoke to be lower than the upper surface 18a of the side leg. Rising parts 19a, 19a from the upper surface 17a of the central leg to the upper surfaces 18a, 18a of the side leg are provided in a curved surface, and the lateral protruding size of the legs 12a, 12a are suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a Japanese-type ferrite core used as a magnetic core for coils, noise filters, transformers, etc.

[Prior art] As magnetic cores for coils, noise filters, transformers, etc.,
Traditionally, Japanese-type ferrite cores have been widely used. FIG. 5 is a perspective view of a conventional standard Japanese-type ferrite core, with a pair of side legs 2 facing each other with a central leg 1a in between.
a and 2a are arranged, and both ends thereof are connected to each other by a yoke portion 4a.

When these Japanese-type ferrite cores are incorporated into a small transformer or the like, a coil bobbin 5a is inserted into the central leg 1a of the Japanese-type ferrite core as shown by the imaginary line in FIG. is wound.

In recent years, there has been an increasing demand for miniaturization of electronic devices, and there is a strong demand for miniaturization of the coils, noise filters, and small transformers used in these electronic devices, as well as the Japanese-type ferrite cores used as their magnetic cores. Various proposals have been made so far.

FIG. 6 is a perspective view showing another Japanese-type ferrite core proposed previously. The outer diameter dimension when assembled into a coil bobbin etc. is determined by the height of the coil bobbin in the height direction, but the width is determined by the thickness of the side leg and the two yoke portion, so the side leg 2b , 2b and the yoke portion 4b are each formed to be flat in the vertical direction, which is effective because the outer diameter dimension in the lateral direction can be reduced.

Next, a conventional method for manufacturing a ferrite core will be described. First, a binder is added to magnetic material powder and granulated. Next, the granulated powder is filled into the mold frame of a dry molding press, and pressure molded using an upper mold and a lower mold to obtain a molded body.

The obtained molded body is fired at a high temperature to obtain a sintered ferrite core of desired dimensions.

Here, the molding means used in the above molding process will be explained. First of all, Fig. 7 shows the main part of the mold of a single-acting press used for molding conventional, general day-type cores, and Fig. 7(a) is a plan view of the formwork. , Figure 7 (b
) is a BB sectional view of the main part of the mold. Granulated powder 33 is filled into a recess formed by a mold frame 30 and a lower mold 31, and pressurized with an upper mold 32 as shown in FIG. 7(b).

On the other hand, Fig. 8 shows the main parts of the mold part of a double-acting press used for molding complex-shaped date cores.
FIG. 8(a) is a plan view of the mold 40, and FIG. 8(b) is a CC sectional view of the main part of the mold.

In the case of the above double-acting press, the pressure surface of the lower mold 41 corresponding to the pressure surface 42a of the upper mold 42 is divided into a plurality of parts, and each divided pressure surface 41a, 41b can be operated individually. This structure allows the filling amount of granulated powder and pressurizing conditions to be set according to each part of the molded body.

The features of the former single-acting press mentioned above are that when it comes to molded products with equal cross sections in the height direction, a molded product with uniform density in each part can be obtained, and because the operation is simple, the molding equipment is small and simple. It has the advantage of a simple structure and fast molding speed, making it suitable for mass production. On the other hand, the latter double-acting press has the advantage that a molded body having a small difference in density between parts can be obtained even when the cross section differs in the height direction.

[Problems to be Solved by the Invention] By the way, among the conventional Japanese-type ferrite cores, the fifth
As shown in the figure, the Japanese-type ferrite core with the same cross-sectional shape in the height direction can be manufactured at low cost because it can be mass-produced using the former single-acting press.
As shown in FIG. 6, when a Japanese-type ferrite core having a structure in which a pair of side legs and a yoke are formed flat in the height direction is molded using a single-acting press, the molding density of each magnetic leg and A large difference occurs between the molding densities of the yoke portions, resulting in problems such as cracks occurring at the boundaries between each magnetic leg and the yoke portions, or deterioration of magnetic properties.

For this reason, the latter double-acting press must be used for molding, which unavoidably complicates and enlarges the equipment and reduces the speed of the molding process as a result.

Therefore, the object of the present invention is to provide a Japanese-type ferrite core that has uniform molding density in each part of the molded product, does not cause cracks, has a small outer diameter, and can be manufactured at low cost using simple equipment. It is about providing.

[Means for Solving the Problems] In order to achieve the above object, the Japanese ferrite core of the present invention has a central leg, a pair of side legs facing each other so as to sandwich the central leg, and the central leg. In a Japanese-type ferrite core comprising both end sides and a yoke portion that connects both end sides of the side legs to each other, the lower surfaces of the center leg, the side legs, and the yoke portion are arranged on the same plane, and , has a structure in which the upper surface of the central leg is continuously lower than the upper surface of the side legs from the upper surface of the central leg to an axially extending portion of the upper surface of the yoke part.

[Function] In the present invention, the lower surfaces of the central leg, the side legs, and the yoke portion are arranged on the same plane, and the central leg of the upper surface of the yoke portion extends from the upper surface of the central leg. Since it has a structure that is continuously lower than the upper surface of the side leg over the axially extending portion thereof, the protrusion dimension of the side leg portion in the lateral direction is suppressed.

In addition, because it has the above structure, after obtaining a molded body with uniform molding density in each part using a single-acting press, etc., it can be processed by simple and general cutting using a rotating disk type grinder or rotating belt type Sangu. A molded body can be easily obtained by cutting the molded body.

[Example] Next, an old type ferrite core of the present invention will be explained with reference to FIGS. 1 to 4. FIG. 1 is a perspective view showing a first embodiment of the old type ferrite core of the present invention, and FIG. 2(a) is a plan view of the Japanese type ferrite core shown in FIG. b) is a sectional view taken along line A-A of the same ferrite core. As shown in FIG. 1, FIG. 2(a), and FIG. 2(b), a pair of side legs 1 are sandwiched between the central leg 11a.
2a and 12a are arranged to face each other, and both ends of these magnetic legs are connected to each other by a yoke portion 14a. Further, the lower surfaces of the central leg 11a1 side legs 12a, 12a, and the yoke portion 14a are arranged on the same surface 16a, and from the upper surface 17a of the central leg,
An upper surface 18a of the side leg continuously extends over the axially extending portion of the central leg 11a of the upper surface of the yoke part,
18a, and rising portions 19a, 19a extending from the upper surface 17a of the central leg toward the upper surface 18a, 18a of the side legs are set as curved surfaces, and the second
As shown in Figure (b), the side legs 12a, the lateral protrusion dimension of the 12a portion is suppressed.

This makes it possible to provide coils, noise filters, transformers, etc. with small outer diameter dimensions.

Next, the manufacturing process of the day type ferrite core of the same example will be explained. FIGS. 3(a) and 3(b) are perspective views showing the main parts of the manufacturing process of the same embodiment.

First, using a single-acting press, a molded body 10a1 having a substantially sun-shaped cross section that is equal in the thickness direction, that is, the center leg 11a1, the side legs 12a, 12a, and the yoke portion 14a that connects both ends of these to each other are made equal to each other. molded to height. Next, as shown in FIG. 3(b), the molded body is moved relative to the molded body while being in contact with the cutting surface 20b of the rotary disc type grinder 20 whose outer circumferential edge is curved. As shown in FIG. 1, the side legs are cut continuously from the upper surface 17a of the central leg 11a to the axially extending portion of the central leg 11a on the upper surface of the yoke portion. A molded body whose height is lower than the upper surfaces 18a, 18a is obtained. Further, in this cutting process, rising portions 19a, 19a extending from the upper surface 17a of the central leg 11a to the upper surfaces 18a, 18a of the side legs are formed into curved surfaces, depending on the shape of the cutting surface of the grinder. By firing this molded body, a day-type ferrite core of the present invention can be obtained.

As shown in the above example, when molding the Japanese-type ferrite core of the present invention, it is sufficient to simply combine a single-acting press and general cutting means, and these steps are performed continuously in the manufacturing process. This can speed up the core molding process compared to when using a conventional double-acting press.

In this example, a single-acting press was used as the pressure molding means for the core, but the present invention is not limited to this. Furthermore, a wet extrusion molding machine with excellent mass productivity can be used to form a long length having a mouth-shaped cross section. After obtaining the length of the molded body, it is possible to cut it into a predetermined size, and although a rotating disc type grinder was used as the cutting means in this example, the present invention is not limited to this. Instead, it is possible to use various common cutting means such as a rotary belt type saw.

Further, in this example, the cutting process was performed on the unfired molded body of the ferrite core, but the present invention is not limited to this. This is possible even after the body is made into ferrite.

Next, a Japanese-type ferrite core according to another embodiment of the present invention will be described. FIG. 4 is a perspective view showing the same ferrite core, and as in the first embodiment, a pair of side legs 12b, 12b are arranged opposite to each other so as to sandwich a central leg 11b.
Both ends of these magnetic legs are connected to each other by yoke portions 14b. Furthermore, the lower surfaces of the side legs 12b, 12b of the central leg 11b1 and the yoke part 14b are arranged on the same plane, and the central leg of the upper surface of the yoke part is connected from the upper surface 17b of the central leg. The upper surface 18b of the side leg is configured to be lower than the upper surface 18b of the side leg continuously over the axially extending portion of the central leg 11b, and the upper surface 18b of the side leg 18b is lower than the upper surface 18b of the central leg.
It has a structure in which the rising portions 19b, 19b extending toward the 8b side are set at an obtuse angle.

In addition, as shown in the above two embodiments, the rising portion from the upper surface of the central leg to the upper surface of the side leg has a curved surface or an obtuse angle structure, so that it can be used during cutting or after cutting. In addition, when a crack occurs from the rising portion, <<, ゛Also, when performing continuous cutting work using the general cutting means as described above,
The ridge portion of the cutting surface of the cutting means corresponding to the rising portion is less deformed due to wear or the like. As a result, a date-type ferrite core with excellent magnetic properties and a structure that is less likely to cause defects in appearance can be obtained.

[Effects of the Invention] According to the present invention, the molding density of each part of the molded body is uniform, and no cracks or the like occur. It is possible to provide a Japanese-type ferrite core that can be

Further, according to the present invention, after a molded body with uniform molding density in each part is obtained in advance using a single-acting press or the like, a simple and general cutting process such as a rotary disc type grinder or a rotary belt type Sangu is performed. Since the molded body can be obtained by cutting by means, it is possible to provide a Japanese-type ferrite core that can be manufactured at low cost using simple equipment.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a first embodiment of a Japanese-type ferrite core according to the present invention, and FIG. Figures (a) and (b) are a plan view and a cross-sectional view of the same ferrite core, respectively, and Figure 3 (
a) and (b) are respectively perspective views for explaining the main parts of the molding process of the same ferrite core, FIG. 4 is a perspective view showing another embodiment of the Japanese type ferrite core in the present invention, and FIGS. FIG. 6 is a perspective view showing a conventional Japanese-type ferrite core, and FIGS. 7(a) and (b) are main parts of a mold used in the conventional general Japanese-type ferrite core molding process. A plan view and a sectional view showing the
1A and 2B are a plan view and a cross-sectional view, respectively, showing the main parts of a mold part used in the molding process of a Japanese type flight light core having a complicated shape. 11a, 1lb 12a, 12b 14a, 14b 15a, 15b 16a ・ ・ 17a, 17b 18a, 18b 19a, 19b ・Central leg・Side leg・Yoke part・Coil bobbin・Bottom surface of core・Top surface of center leg・Top surface of side leg・Rising part

Claims (1)

[Claims] A Japanese-type ferrite core comprising a central leg, a pair of side legs facing each other so as to sandwich the central leg, and a yoke portion that connects both ends of the central leg and both ends of the side legs. , the lower surfaces of the central leg, the side legs, and the yoke portion are arranged on the same plane, and from the upper surface of the central leg to the axially extending portion of the upper surface of the yoke portion of the central leg. A Japanese-type ferrite core, characterized in that the core is continuously lower than the upper surface of the side leg.