JP2005294860A - Ferrite core - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the whole ferrite core from twisting and to hereby enable highly precise polishing. <P>SOLUTION: A flat recess 6A is formed at the center of a rear face 6 of a ferrite core 1 to form an installation surface 7 with part of an end of the rear face 6 left, and regions extending from the recess 6A to the installation surface 7 are formed to be arcuate parts 6B and 6B. Thus, thermal deformation of the ferrite core 1 in baking or deformation in cooling can be eliminated, thereby highly precisely polishing surfaces of outer legs 2 and a center leg 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a ferrite core improved so as to improve the processing accuracy of the ferrite core.

  As shown in FIG. 22, the ferrite core used in the transformer is in a state in which a coil is wound around a pair of ferrite cores 1 having the same shape, and the outer leg portion 2 and the center leg portion 3 are in contact with each other. Use. Since the loss of the transformer depends on the adhesion between the outer leg portion 2 and the central leg portion 3, these mating surfaces 4 are subjected to high-precision polishing. In this polishing, as shown in FIG. 21, the polishing surface 4 is polished by bringing the back surface 6 of the ferrite core 1 into close contact with the polishing table 5. Moreover, the ferrite core 1 shape | molds the ferrite powder used as a core material with a metal mold | die etc., and grinds the mating face 4 after baking.

  Conventional ferrite cores are disclosed in Patent Documents 1 to 3, respectively. The outline will be described with reference to FIGS. First, the ferrite core 1 shown in FIG. 18 has the back surface 6 as a flat surface, and the installation surfaces 7 projecting at both ends thereof are formed to eliminate the thermal deformation and the deformation at the time of firing. The adhesion is improved and the processing accuracy of the mating surface 4 is increased.

  Further, as shown in FIG. 19, the back surface 6 of the ferrite core 1 is curved, and the installation surfaces 7 are formed at both ends of the curved back surface 6. FIG. 20 is a cross section taken along line AA of the back surface 6. The back surface 6 is a flat surface.

JP 59-14620 A Japanese Patent Publication No. 63-55854 JP-A-6-151204

  However, each of the above conventional examples has the following problems. That is, when the ferrite core 1 is placed on the polishing table 5, the installation surface 7 is not in close contact with the polishing table 5, and when the polishing surface 4 is polished, the ferrite core 1 is shaken and high-precision polishing cannot be performed. There was a problem. The reason is considered to be that the entire ferrite core 1 is twisted due to thermal deformation when it is molded with a mold and fired or deformation during cooling.

  Thus, when the flatness of the back surface is not obtained, it is necessary to process the back surface to polish the flatness, resulting in a problem that the productivity is lowered and the cost is increased accordingly. .

  The present invention provides a ferrite core that prevents twisting of the entire ferrite core, enables highly accurate polishing, improves productivity by eliminating the need for processing of the back surface, and reduces the cost.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a ferrite core having an outer leg portion and a center leg portion on the main surface side. Forming a flat surface concave portion in the central portion, leaving a flat surface as a chamfering installation surface in a part of the end portion on the back surface of the ferrite core, and forming a region from the flat surface concave portion to the chamfering installation surface. It is characterized by being formed in an arc shape.

  The invention described in claim 2 is characterized in that four chamfered installation surfaces are formed in the plane of the back surface of the ferrite core.

  The invention described in claim 3 is characterized in that two chamfering installation surfaces are formed in the plane of the back surface of the ferrite core.

  According to the invention of claim 1, by forming the back surface of the ferrite core in the combined concave portion of the flat surface concave portion and the arcuate surface so as to form the installation surface while leaving a part of the end portion of the ferrite core rear surface, Since the ferrite core is free from thermal deformation during firing and cooling, the surfaces of the outer leg portion and the center leg portion can be polished with high accuracy, and the loss of the transformer can be minimized. Further, it is not necessary to process the flatness of the back surface of the ferrite core, so that productivity can be improved and the cost can be reduced.

  According to the invention of claim 2 or 3, since four or two installation surfaces are formed in the plane of the back surface of the ferrite core, the ferrite core can be installed on the polishing table in a stable state, The surface of the outer leg portion and the center leg portion can be polished with high accuracy, and the loss of the transformer can be minimized.

  Embodiments of the present invention will be described below. FIG. 1 is a diagram showing the back surface 6 of the ferrite core 1, and the back surface is formed into a spherical recess so that chamfered installation surfaces 7 are formed at the four corners of the back surface 6. In the figure, G1 represents the contact outer diameter between the back surface 6 and the sphere when forming a spherical surface (hereinafter referred to as a sphere). G2 indicates a contact outer diameter (hereinafter referred to as an elliptical sphere, and a surface formed by the elliptical sphere is referred to as an elliptical spherical surface) between the back surface 6 and the rugby ball-shaped object when an approximate spherical surface is formed. . When the back surface 6 is formed with the sphere G1, the curvature radius R1 of the back surface 6 is the same in the front view 3 and the side view 4 of the ferrite core 1, and the back surface 6 is a spherical recess. When the back surface 6 is formed with the elliptical sphere G2, the radius of curvature of the back surface 6 in FIGS. 3 and 4 is R2 and R3 along the outer diameter of the elliptical sphere.

  The ferrite core 1 shown in FIG. 5 and FIG. 6 is obtained by changing the outer leg portion 2 and the central leg portion 3 to different ferrite cores 1 and the back surface 6 by a spherical concave portion or an elliptic spherical concave portion. 1 is a ferrite core 1 in which the size, length L1 × width W2 of the back surface 6 is relatively close to a square, and chamfered installation surfaces 7 are formed at the four corners of the back surface 6.

  Next, the ferrite core 1 shown in FIG. 7 has an elongated shape with a length L1 × W1, and when the back surface 6 is formed with the sphere G1 in the ferrite core 1, as shown in FIG. The chamfering installation surface 7 is formed at both ends of the back surface 6. Also in this case, the back surface 6 is a spherical surface formed by the sphere G1. Moreover, when it shape | molds with the elliptical spherical body G2, the chamfering installation surface 7 can be formed in the four corners of the back surface 6, as shown in FIG. In this case, the back surface 6 is an elliptical spherical recess along the outer diameter of the elliptical sphere G2.

  The example shown in FIG. 10 and FIG. 11 is a ferrite core 1 having a cut portion 8, and when the back surface 6 is formed with a sphere G 1, the chamfered installation surfaces 7 are formed at both ends of the back surface 6 as shown in FIG. Is done. Also in this case, the back surface 6 is a spherical surface formed by the sphere G1. Moreover, when it shape | molds with the elliptical spherical body G2, the chamfering installation surface 7 can be formed in the four corners of the back surface 6, as shown in FIG. In this case, the back surface 6 is an elliptical spherical recess along the outer diameter of the elliptical sphere G2.

  FIG. 13 shows a ferrite core 1 in which the shape of the back surface 6 is complicated. First, when the back surface 6 is formed with the sphere G1, the chamfered installation surfaces 7 can be formed at both ends of the back surface 6 as shown in FIG. 14, and when the back surface 6 is formed with the sphere G2, the surface is shown in FIG. The chamfering installation surface 7 having such a large area can be formed, and when the back surface 6 is formed with an elliptical sphere G3, four chamfering installation surfaces 7 are formed as shown in FIG. Can do. And the back surface 6 becomes a spherical recess or an elliptical recess. FIG. 17 is an external view of the ferrite core 1 in FIG.

  Thus, if the back surface 6 is a spherical surface or an elliptical spherical concave portion, the back surface 6 corresponding to the ferrite core 1 having a complicated shape can be obtained. As shown in FIG. 1 to FIG. 11 and FIG. 13 to FIG. 17, the ferrite core 1 with the back surface 6 made into a spherical recess and the elliptical spherical recess was actually molded with a mold and fired. No twist appeared in the core 1, and the chamfered installation surface 7 could be in the same plane as the back surface 6, and the polishing table 5 and the installation surface 7 could be brought into close contact with each other.

  The technical reason that such an effect can be obtained is not clear, but the following can be considered. The surface pressure P on the back surface when the core material ferrite powder is filled and pressed is uniform as shown in FIGS. 3 and 4 (principle of spherical body). Becomes even. The rigidity of the spherical surface is higher than that of the flat surface. The curved surface has a high rigidity force on the curved side, but the rigidity force on the non-curved side (see FIG. 20) is low, and the rigidity on the entire back surface is different. The rigidity force is substantially uniform with respect to this force, and the rigidity force is more uniform and higher than the curved surface with respect to thermal deformation during firing and deformation during cooling. In the case of an elliptical spherical surface, it is considered that they are approximately the same. It is considered that the characteristics of such a spherical surface are organically related to each other to prevent twisting of the ferrite core.

  The shape of the recess on the back surface of the present invention will be described in more detail with reference to FIG. As shown in FIG. 12, a flat surface recess 6A formed in the central portion of the back surface of the ferrite core 1 ′ and arc-shaped portions 6B and 6B formed in a region from the flat surface recess to the end chamfering installation surface. It is a formed recess (so-called bowl-shaped recess). By configuring in this way, the above-described effects can be obtained.

It is an embodiment of the present invention, and is a plan view showing the relationship between a ferrite core whose back surface is nearly square, and a sphere and an elliptical sphere. It is a perspective view which shows the back surface of the ferrite core which shape | molded the back surface with the spherical body or elliptical sphere of FIG. It is an embodiment of the present invention and is a front view of a ferrite core. FIG. 4 is a side view of FIG. 3. It is a perspective view of the ferrite core which formed the back surface using the spherical body or elliptical spherical body shown in FIG. It is a perspective view of the ferrite core which formed the back surface of the ferrite core from which an outer leg part and a center leg part differ using the sphere or elliptical sphere shown in FIG. It is an embodiment of the present invention, and is a plan view showing a relationship between a ferrite core having a relatively long back surface, a sphere, and an elliptical sphere. It is a perspective view which shows the back surface of the ferrite core which formed the back surface with the spherical body in FIG. It is a perspective view which shows the back surface of the ferrite core which formed the back surface with the elliptical sphere in FIG. It is a perspective view which shows the back surface of the ferrite core which formed the back surface in the back surface which has a notch part with the spherical body in FIG. It is a perspective view which shows the back surface of the ferrite core which formed the back surface in the back surface which has a notch part by the elliptical sphere in FIG. It is a top view of the ferrite core which shows other embodiment of this invention. It is an embodiment of the present invention, and is a plan view showing a relationship between a ferrite core having a complicated shape on the back surface, and a sphere and an elliptical sphere. It is a top view which shows the back surface of the ferrite core which formed the back surface with the spherical body in FIG. It is a top view which shows the back surface of the ferrite core which formed the back surface with the spherical body in FIG. It is a top view which shows the back surface of the ferrite core which formed the back surface with the elliptical sphere in FIG. FIG. 14 is a perspective view of the ferrite core in FIG. 13. It is a front view of the conventional ferrite core. It is a front view of the conventional ferrite core. FIG. 20 is a longitudinal sectional view taken along line AA in FIG. 19. It is explanatory drawing shown about grinding | polishing of a ferrite core. It is explanatory drawing which showed the use condition of the ferrite core.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ferrite core 2 ... Outer leg part 3 ... Center leg part 4 ... Matching surface 5 ... Polishing stand 6 ... Back surface 7 ... Installation surface 8 ... Cut part

Claims (3)

  In a ferrite core having an outer leg portion and a central leg portion on the main surface side, a part of the end portion is formed on the back surface of the ferrite core so as to form an installation surface while leaving a part of the side edge of the ferrite core back surface. The ferrite core is characterized in that a flat surface concave portion is formed in the central portion, leaving a flat surface as a chamfering installation surface, and a region extending from the flat surface concave portion to the chamfering installation surface is formed in an arc shape.   2. The ferrite core according to claim 1, wherein four chamfering installation surfaces are formed in a plane on the back surface of the ferrite core. The ferrite core according to claim 1, wherein two chamfered installation surfaces are formed in a plane on the back surface of the ferrite core.

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