JPH0795487B2 - E type core - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an E-shaped core made of a magnetic material used for a magnetic core such as a transformer, a choke coil, and a noise filter. The present invention relates to an E-shaped core whose structure is effectively utilized.

(Prior Art) In recent years, there has been an increasing demand for miniaturization of electronic devices, and in particular, there has been a demand for thin and lightweight electronic devices that can be carried and used outdoors or indoors.

For this reason, transformers, choke coils, noise filters and the like used in these electronic devices are also desired to be small and lightweight.

Therefore, even for a core made of a magnetic material used as a magnetic core of the transformer, choke coil, noise filter, etc., there is a strong demand for thinning and weight reduction, and various proposals have been made so far. .

An E-type core is generally used as a magnetic core incorporated in the transformer or the like, and a conventional example of the E-type core will be described with reference to FIG.

An E-shaped core 1 made of a magnetic material such as ferrite has a pair of first side magnetic legs 3 and a pair of first side magnetic legs 3 each having a first groove 6 and a second groove 7 on both sides of a central magnetic leg 2 having a substantially square cross section. The second magnetic leg 4 is arranged, and one end of each of the central magnetic leg 2, the first magnetic leg 3 and the second magnetic leg 4 is connected by a yoke portion 5.

At this time, the other end surfaces of the central magnetic leg 2, the first magnetic leg 3 and the second magnetic leg 4 are formed on the same plane, and
In order to optimize the magnetic characteristics of the die core 1, the central magnetic leg 2
Is formed to be equal to the sum of the cross-sectional areas of the first magnetic leg 3 and the second magnetic leg 4.

When the E-shaped core 1 is assembled in a transformer or the like, a coil bobbin 8 made of a coil around which an enamel wire or the like is wound is fitted to the central magnetic leg 2 as shown by a phantom line in FIG. Further, it is fixed in combination with an E-type or I-type core by a fixing fitting or the like not shown.

When the coil bobbin 8 is fitted to the E-shaped core 1, the upper and lower windings of the coil bobbin 8 are projected in the Z width from the upper and lower surfaces of the central magnetic leg 2 of the E-shaped core 1, and thus the E-shaped core 1 It cannot be said that the dimensions of each part are effectively utilized in the structural design of.

Moreover, when the transformer or the like is mounted on an electronic circuit board or the like, there is a problem that the protruding Z-width winding portion serves as a mounting portion on the board or the like and thus is not stable.

Therefore, while satisfying the condition that the cross-sectional area of the central magnetic leg is equal to the sum of the cross-sectional areas of the first-side magnetic leg and the second-side magnetic leg, the E-shaped core has been designed to effectively utilize the dimensions of each part Has been devised, and this E-type core will be described with reference to FIG.

The E-shaped core 11 has a laterally elongated central magnetic leg 12 extending from the lower center of the front path of the yoke portion 15, and has a first groove 16 and a second groove on both sides of the central magnetic leg 12. A first side magnetic leg 13 and a second side magnetic leg 14 are provided with 17, and one ends of the first side magnetic leg 13 and the second side magnetic leg 14 are connected by the yoke portion 15. .

Further, the E-shaped core 11 includes the central magnetic leg 12 and the first side magnetic leg 13
And the other end surface of the second magnetic leg 14 is formed on the same surface, and the lower surfaces of the central magnetic leg 12, the first magnetic leg 13 and the second magnetic leg 14 are formed on the same surface. It is composed by.

A coil bobbin 18 is fitted to the central magnetic leg 12 of the E-shaped core 11 as shown by an imaginary line in the figure, and further combined with an E-shaped or I-shaped core to form a transformer or the like. It has become so.

According to the E-shaped core 11, since the central magnetic leg 12 is elongated in the lateral direction, the height of the central magnetic leg 12 is increased by the first magnetic leg 13, the second magnetic leg 14, and The height of the yoke portion 15 is lower than that of the yoke portion 15, so that there is a space above the central magnetic leg 12 and the coil bobbin fitted to the central magnetic leg 12 is provided.
The upper winding portion of 18 does not project above the upper surfaces of the first side magnetic leg 13, the second side magnetic leg 14, and the yoke portion 15, and therefore, the structural design corresponding to the downsizing of the E-shaped core 11 is achieved. Has been done.

The E-shaped core 11 is molded by pressing a magnetic material with a double-acting press machine (not shown) having a plurality of pressing surfaces, for example.

According to the above-mentioned double-acting type press machine, since each pressurizing surface interlocks in multiple ways to press the magnetic material, it is difficult to mold the magnetic material so as to have a uniform density. When the double-acting pressure is applied, internal stress may cause micro cracks or the like in the E-shaped core 11.

Further, the double-action press machine is large in size, complicated in operation control, and slow in molding speed, so that it is not suitable for mass production.

Therefore, a method for manufacturing an E-shaped core as shown in FIGS. 5 (a) to 5 (d) has been proposed.

According to this method, a magnetic material is molded into a molding member 28 by a single-acting type press device (not shown) (FIG. 7A), and the molding member 28 is cut into cutting grooves 27a and 27b by, for example, a lathe. ((B) in the figure).

Next, the molding member 28 is sequentially cut into a predetermined width (FIG. 7C), and the substantially central upper portion of the cut piece is cut to form the first magnetic leg 23 on both sides of the central magnetic leg 22. And a second magnetic leg 24 are arranged and formed, and a yoke portion for connecting one end of each of the central magnetic leg 22, the first magnetic leg 23, and the second magnetic leg 24.
The E-shaped core 21 in which 25 is formed is manufactured.

The E-shaped core 21 has a central magnetic leg cutting portion 26a and a yoke portion 25 formed by cutting the upper surface of the central magnetic leg 22 by cutting.
A cutting groove portion 26 formed by cutting the upper surface of the yoke portion forming the same plane as the yoke portion cutting portion 26b is formed, and the width W4 ′ of the yoke portion cutting portion 26b of the cutting groove portion 26 is equal to that of the central magnetic leg cutting portion 26a. width
The yoke cutting portion 26b is formed wider than W1 '.
It was general that the notch 30 (which is a part of the cutting groove 26) was formed on both sides of the.

The structure of the E-shaped core 21 is described in, for example, Japanese Utility Model Laid-Open No. 64-37011.

The E-shaped core 21 has a coil bobbin (not shown) having a central magnetic leg.
The transformer and the like are configured by being fitted to the core 22 and being combined with another E-type or I-type core.

At this time, since the cutting groove portion 26 is formed,
As shown in FIG. 6, the height H1 'of the central magnetic leg 22 is different from the height H2' of the first side magnetic leg 23 and the second side magnetic leg 24.
Since H1 ′ <H2 ′, the upper winding portion of the coil bobbin is prevented from protruding from the upper surfaces of the first side magnetic leg 23 and the second side magnetic leg 24, and is stable to an electronic circuit board or the like. It contributed to mounting and miniaturization.

According to the method for manufacturing the E-shaped core, it is not necessary to use the double-acting press machine, and the E-shaped core 21 can be manufactured by a general apparatus and process.

Further, as shown in FIG. 7, an E-shaped core 31 having a shape different from that of the E-shaped core 21 is described in Japanese Utility Model Laid-Open No. 2-8117 No.
As shown in the drawing, a pair of first side magnetic legs 33 and a second magnetic leg 33 having cutting grooves 37a and 37b on both sides of the central magnetic leg 32 are provided.
The side magnetic leg 34 is arranged, and one end of each of the central magnetic leg 32, the first side magnetic leg 33, and the second side magnetic leg 34 is connected by a yoke portion 35.

Further, in the E-shaped core 31, the upper surface of the central magnetic leg 32 is cut to a height H1 ', and the yoke portion 35 is formed.
Is cut at a height H3 ', which is higher than the height H1', with a tapered portion 40 to form a cutting groove portion 36.

In the cutting groove portion 36 of the E-shaped core 31, the upper surface of the cut central magnetic leg 32 and the upper surface of the yoke portion 35 are not flush with each other.

(Problems to be Solved by the Invention) However, according to the conventional E-shaped cores 21 and 31, at each contact portion that forms a boundary between each magnetic leg and each yoke surface, each surface has a corner. When the central magnetic leg and the yoke portion are cut, or when the coil bobbin is fitted and assembled to the central magnetic leg, internal stress is concentrated on the contact portion and cracks are formed. Is likely to occur,
There is a problem that the cracks lower the magnetic properties and the physical strength.

The present invention has been made in view of the above circumstances, and cracks are generated at the boundary contact portion between each magnetic leg and the yoke portion and / or at the boundary contact portion between the cut surface of the yoke portion and the rising surface from the notch. This is to provide an E-shaped core that prevents this.

(Means for Solving the Problems) The present invention is directed to a central magnetic leg and a pair of first and second magnetic poles arranged so as to face each other so as to sandwich the central magnetic leg from the left and right with the first and second grooves interposed therebetween.
An E-shaped planar shape having an E-shape having a first and second magnetic legs, and a yoke portion that connects one end of the central magnetic leg and one end of each of the pair of first and second magnetic legs to each other. The width of the yoke portion of the core is made wider than the width of the first and second magnetic legs, and at least one of the central magnetic legs on the E-shaped surface and a part of the yoke portion are connected to the central magnetic legs. Cutting along the first and second grooves provided between the first and second magnetic legs so as to be wider than the width of the central magnetic leg and lower than the height of the first and second magnetic legs. In the machined E-shaped core, the machined cutting surface is between the widths of the first and second grooves, and two rising cutting surfaces are formed by cutting the yoke portion in parallel to the magnetic leg direction, and a central magnetic surface. Central magnetic leg cutting part made by cutting the upper surface of the leg horizontally and yoke part cutting made by cutting the upper surface of the yoke part horizontally And a boundary contact portion between the yoke portion and each magnetic leg, and a boundary contact portion between the rising cutting surface from the cutting groove portion in the yoke portion, and at least one of The above object is achieved by providing an E-shaped core characterized by being processed so as to be bent.

(Operation) In the present invention, by making the width of the yoke portion of the E-shaped core wider than the width of the side magnetic leg, the cross-sectional area of the first side magnetic leg or the second side magnetic leg Since the cross-sectional area of the excess cutout portion of the yoke portion is protected from becoming small, the excess cutout portion is provided even when a high load is applied to the transformer or the like in which the E-shaped core is incorporated. The occurrence of magnetic saturation below a predetermined characteristic value in the part is prevented.

In addition, the central magnetic leg on at least one E-shaped surface of the E-shaped core and a part of the yoke portion are provided between the central magnetic leg and the first and second side magnetic legs, Since the cutting is performed along the second groove so as to be wider than the width of the central magnetic leg and lower than the heights of the first and second magnetic legs, the cutting position is slightly displaced during the cutting. However, there is no possibility that a convex portion which is not cut will remain on the central magnetic leg surface, and it is possible to prevent the appearance defect from occurring.

Further, the E-shaped core has two rising cutting surfaces formed by cutting a machined cutting surface between the widths of the first and second grooves and cutting the yoke portion in parallel with the magnetic leg direction, and a central magnetic field. In addition to a central magnetic leg cutting part made by cutting the upper surface of the leg horizontally and a cutting groove part on the same surface consisting of the yoke part cutting part made by cutting the upper surface of the yoke part horizontally,
By the boundary contact portion between the yoke portion and each magnetic leg, and the boundary contact portion between the cutting groove portion of the yoke portion and the rising cutting surface, at least one is processed and formed to form a curved portion, When cutting the central magnetic leg and the yoke part, or when assembling and assembling the coil bobbin on the central magnetic leg, the internal stress concentrated at the boundary contact part is dispersed to reduce or prevent the generation of microcracks. it can.

(Example) The Example of this invention is described in detail based on drawing.

FIG. 1 is a perspective view showing an embodiment of an E-shaped core according to the present invention, and FIG. 2 (a) is a plan view showing the E-shaped core of the same embodiment.
FIG. 2 (b) is a sectional view showing an XX sectional view of the E-shaped core of the same embodiment.

The E-shaped core 51 shown in FIG. 1 is manufactured by the following steps and the like.

A pair of side pillars (which will be the yoke portion described below) of magnetic material and a pair of common pillars (first and second side magnetic legs described below) that connect both end portions of the side pillars by a single-acting press device or the like. And)
A day-molded member having a central common column (which will be a central magnetic leg described later) connecting the central portions of the pair of side columns is molded.

At this time, in the die of the single-acting type press machine, for example, a boundary contact portion that is a connecting corner portion between the side column and the center common column and the side column and the common column is molded into a curved shape. A curved portion is formed by the mold at a corresponding portion of the member (the curved portion at the boundary contact portion is referred to as a molded curved portion).

Next, horizontally along the central common pillar of the above-mentioned molding tool,
The surfaces of the pair of side columns and the center common column are cut by a disc grinder or the like formed of an abrasive material or the like.

At this time, a disk-type grinder with a curved lower part of the ridge (cutting edge surface) is used for the cutting work, and the cutting width is narrower than the interval between the pair of common columns and smaller than the width of the central magnetic leg. Widely set.

When the disk type grinder is horizontally supported by a rotary shaft at a predetermined height and horizontally rotated while being horizontally moved symmetrically with respect to the date mold member along the central common column direction, the entire upper surface of the central common column is A flat cutting surface formed by cutting is formed, and a part of the side pillar is cut, and rises by the ridge portion of the disc grinder to form the same plane as the two cutting surfaces and the cutting surface of the central common pillar. A cutting surface is formed.

At this time, a portion corresponding to a portion to which the lower portion of the ridge portion of the pair of side columns to be cut by the lower portion of the ridge portion of the disc grinder is in a curved state (a horizontal plane of the two rising surfaces). A curved surface (referred to as a cutting curved portion) due to the cutting is formed at a rising portion from the cutting surface.

The thickness of the disc grinder is presumed to be equal to or greater than the cutting depth, and the predetermined cutting depth is set by adjusting the cutting depth according to the installation height of the rotary shaft mounted on the shaft.

Next, a pair of E-shaped cores are manufactured by cutting the pair of common pillars and the center common pillar of the day molding member at approximately the center.

The E-shaped core 51 manufactured as described above is formed by pressing the central magnetic leg 5 as shown in FIG.
2. The boundary contact portion connecting the first side magnetic leg 53, the second side magnetic leg 53, and the yoke portion 55 is formed as a curved curved portion 69.

Further, in the E-shaped core 51, a part of a side pillar that becomes the yoke portion 55 in the disc grinder is a central common pillar (central magnetic leg).
By cutting along the center magnetic leg cutting part 61
A yoke cutting portion 61b on the same plane as a is formed, and a rising surface 71 is formed as a curved curved cutting portion 70 at a boundary contact portion with the yoke cutting portion 61b.

According to the E-shaped core 51 configured as described above, the central magnetic leg 52, the first side magnetic leg 53, and the second magnetic leg 53 during the press molding process.
By forming the boundary contact portion where the side magnetic leg 54 and the yoke portion 55 are connected to each other in the molding curved portion 69, it is possible to relieve the concentration of the molding processing pressure and the like at the boundary contact portion, so that it is possible to prevent cracks and the like. Occurrence can be prevented.

Further, during cutting by the disc grinder, the ridge portion of the disc grinder is formed into a curved portion, and the boundary contact portion between the central magnetic leg cutting portion 61a and the rising surface 71 corresponding to the ridge portion. By forming the curved portion 70 on the cutting curved portion 70, it is possible to alleviate the concentration of the cutting pressure and the like on the boundary contact portion, so that the occurrence of cracks and the like can be prevented.

Further, since the boundary contact portion where cracks and breaks are most likely to occur is reinforced, it is possible to prevent cracks and damages due to internal stress when the E-shaped core is fitted to the coil bobbin and in subsequent assembly steps.

The molding curved portion 69 and the cutting curved portion 70 are not limited to those formed by molding and cutting, respectively, and each portion of the E-shaped core 51 can be arbitrarily processed by using each processing method. You may form.

Further, as a precaution, another important structural characteristic of the E-shaped core 51 according to the present invention will be described. The central magnetic leg cutting portion 61a formed by cutting and the yoke portion cutting portion 61b are the same. While forming the cutting groove portion 61 on the surface, the width W1 of the central magnetic leg cutting portion 61a and the width W4 of the yoke portion cutting portion 61b have a relationship of W1 <W4. The part from which is subtracted is a surplus notch 60 that is cut to approximately the center of the first groove 56 and the second groove 57.

Therefore, even if the horizontal cutting position is slightly deviated during the cutting process, it is possible to prevent the convex portion, which is not cut, from remaining on the upper surface of the central magnetic leg 52.

Further, even if the excess cutout portion 60 is formed in the yoke portion 55, as can be seen by referring to FIG. 2A, the width W2 of the first side magnetic leg 53 or the second side magnetic leg 54 and the yoke The relationship with the width W3 of the portion 55 is
The yoke portion 55 is wider than the first side magnetic leg 53 and the second side magnetic leg 54 so that W2 <W3, and the cross-sectional area of the central magnetic leg 52 is the first side magnetic leg 53 and the second side magnetic leg 53. Since it is the sum of the cross-sectional areas of the side magnetic legs 54 and the sum of the cross-sectional areas of the left and right excess cutout portions 60 of the yoke portion 55, magnetic saturation below a predetermined characteristic value can be avoided.

As shown in FIG. 2B of the E-shaped core 51, the cross-sectional area of the central magnetic leg 52 is twice the cross-sectional area of the first magnetic leg 53 and the second magnetic leg 54. And the height of the central magnetic leg 52
H1 is formed to have a height lower than the height H2 of the first magnetic leg 53 and the second magnetic leg 54.

That is, when the coil bobbin 65 (indicated by phantom lines) formed of a coil or the like on which an enamel wire or the like is wound is fitted to the central magnetic leg 52, one winding portion of the coil bobbin is The side magnetic leg 53 and the second side magnetic leg 54 do not protrude beyond the height H2.

Therefore, the E-shaped core 51 to which the coil bobbin is mounted is
A transformer or the like incorporated with another E-type or I-type core can be stably mounted on an electronic circuit board or the like.

Finally, when iron powder is applied to the magnetic material, a dust core is formed by pressure molding, and when ferrite powder is applied, granulation is performed by adding a binder to the ferrite powder, A ferrite core is formed by pressure molding and further firing.

(Effects of the Invention) Since the E-shaped core according to the present invention is configured as described above, the boundary contact portion where each magnetic leg is connected to the yoke portion is formed into a curved curved portion when the molding process is performed. In addition to being formed, the boundary contact portion between the cutting portion of the yoke portion and the rising surface is formed into a curved cutting curved portion at the time of cutting, so that the molding bending portion and the cutting bending portion are subjected to molding processing pressure or the like. It has an excellent effect that the concentration can be relieved and cracks and damages can be prevented from being generated at the boundary contact portion during molding, cutting and assembling steps.

[Brief description of drawings]

1 is a perspective view showing an embodiment of the E-shaped core according to the present invention, FIG. 2 (a) is a plan view showing the E-shaped core of the same embodiment, and FIG. 2 (b) is an E of the same embodiment. Sectional view showing an X-X section of the mold core, FIGS. 3 and 4 are perspective views showing a conventional E-shaped core, and FIGS. 5A to 5D are manufacturing steps of the conventional E-shaped core. FIG. 6 is a sectional view showing a partially cutaway cross section of the conventional example, and FIG. 7 is a sectional view showing a partially cutaway cross section of another conventional example. 51 …… E-shaped core, 52 …… Central magnetic leg, 53 …… First side magnetic leg, 54 …… Second side magnetic leg, 55 …… Yoke part, 56 …… First groove, 57 …… Second Grooves, 60 ... Excessive cutouts, 61a ... Central magnetic leg cutting section, 61b ... Yoke section cutting section, 61 ... Cutting groove section, 69 ... Molding curve section, 70 ... Cutting curve section.

Claims (1)

[Claims] 1. A central magnetic leg, a pair of first and second side magnetic legs arranged to face each other so as to sandwich the central magnetic leg from the left and right with first and second grooves respectively, and the central magnetic leg. The width of the yoke portion of the E-shaped core having an E-shaped planar shape having one end and one of the pair of first and second side magnetic legs connected to each other. The magnetic leg is made wider than the side magnetic leg and at least one central magnetic leg on the E-shaped surface and a part of the yoke portion are provided between the central magnetic leg and the first and second magnetic side legs. Also, in the E-shaped core cut along the first and second grooves so as to be wider than the width of the central magnetic leg and lower than the height of the first and second magnetic legs, the cutting is performed. A surface between the widths of the first and second grooves, and two rising cut surfaces formed by cutting the yoke portion in parallel with the magnetic leg direction, and the center The yoke is formed by a central magnetic leg cutting part formed by cutting the upper surface of the magnetic leg horizontally and a cutting groove part on the same plane formed by the yoke part cutting part formed by cutting the upper surface of the yoke part horizontally. Portion and each magnetic leg, and an E-shaped core processed so as to form a curved portion of at least one of a boundary contact portion between a cutting groove portion of the yoke portion and the rising cut surface of the yoke portion. .