JP4924689B2 - Ferrite grinding body, ferrite core, manufacturing method, grinding method and apparatus - Google Patents

Description

The present invention is a surface mount type ferrite magnetic core that is used as an inductance component such as a transformer and a choke coil and has flanges on both sides, and in particular, a ferrite that can have a highly flexible shape including a substantially polygonal flange on one side. core, ferrites grinding bodies, grinding process, manufacturing method, relates 及 beauty grinding apparatus.

  Ferrite magnetic cores are widely used in surface mount coil components that constitute inductance elements such as transformers and choke coils used in various electronic devices. As this ferrite magnetic core, a drum core having a circular or substantially square flange on both sides is well known. Hereinafter, the ferrite magnetic core is also referred to as a drum core.

  Usually, when a drum core having circular flanges on both sides is used as an inductance element, it is used as shown in FIG. That is, after winding the insulation coated conductive wire 85 around the shaft portion 82 of the drum core 8, it is fixed to the substantially rectangular base 83 with an adhesive 84 or the like, and two terminals of the conductive wire 85 are provided on the base 83. An inductance element is completed by connecting to 86 and 86, respectively.

  As a manufacturing method of the drum core 8 having circular flanges on both sides shown in FIG. 20, after ferrite granules are press-molded into a cylindrical shaped body 80, the ferrite molded body 80 is guided to a guide device as shown in FIGS. The ferrite grinding body in which the circular flanges 81 are formed on both sides is obtained by grinding the desired width by centerless machining by grinding the central portion in the axial direction of the ferrite compact 80 with the grinding blade 91. Obtained by shrinking and densifying by firing. Drum cores can be manufactured with high productivity by continuous press molding and centerless processing.

  However, since the drum core 8 having the circular flanges 81 on both sides has no direction discrimination, other members such as the base 83 are required to make it into an inductance element, and the drum core 8 and the base 83 are required. Had to be fixed using the adhesive 84. Therefore, even if the drum core can be manufactured with good productivity and at low cost, there is a problem that the productivity is low in parts production and the cost is high.

  Further, the height of the componentized element is the sum of the height of the drum core 8 and the thickness of the base 83, and even if the height of the drum core 8 is lowered, the height is increased by the thickness of the base 83. Had. In particular, when used for chip-type elements used in high-density packaging electronic devices, it has been a cause of hindering thickness reduction and weight reduction.

  And in patent document 1, the drum core which does not require a base is disclosed by forming a substantially square collar part on both sides and forming a terminal etc. in one collar part as composition which can be componentized only with a drum core. Has been. However, in the substantially square drum core, it is necessary to grind the quadrangular columnar shaped body 80 by a processing method as shown in FIG. In this case, productivity is not high because each molded body is processed. It is impossible to apply centerless machining that can be continuously machined with high productivity, such as a drum core with circular flanges on both sides.

  Patent Document 2 discloses a drum core in which a flange on one side is circular and a flange on the other side is a square, and a terminal electrode is formed on the rectangular flange. However, there is no description about the manufacturing method.

JP-A-2005-310982 Japanese Utility Model Publication No. 58-187117

The present invention has been made in view of such circumstances, the terminal electrodes can be formed ferrite core on one side, a manufacturing method which can be produced with good productivity the ferrite core, ferrites grinding bodies, Grinding device And a method.

The ferrite ground body according to the present invention is formed by press-forming ferrite granules containing a ferrite material and PVA, and has a first member and a second member that are continuous in the press-forming direction, and the press-forming of the second member. cross sectional area perpendicular to the direction, greater than the cross-sectional area perpendicular to the press-forming direction of the first member, the second member is a ferrite molded product having a 3% to 8% greater density than the density of said first member Is cut so that the cross-sectional area perpendicular to the press molding direction of the portion where the first member and the second member are continuous is smaller than the cross-sectional area perpendicular to the press molding direction of the first member. It is characterized by that.

In the ferrite ground body according to the present invention, the first member has a disk shape, and the cross-section of the second member has at least two corners.

The ferrite ground body according to the present invention is characterized in that the second member has a square plate shape.

In the ferrite ground body according to the present invention, the second member has a rectangular cross section.

The ferrite ground body according to the present invention is characterized in that a cross section of the second member has a shape formed of an arc and a straight line.

  The ferrite magnetic core according to the present invention is characterized by firing the ferrite ground body described above.

The grinding method according to the present invention includes a first member and a second member that are formed by press-molding a ferrite granule including a ferrite material and PVA, and that are continuous in the press-molding direction, and the press-molding direction of the second member. A cross-sectional area perpendicular to the press molding direction of the first member is larger than the cross-sectional area of the first member, and the second member is a ferrite molded body having a density 3% to 8% larger than the density of the first member. , A support means for supporting the ferrite compact with a support surface, and a disk-shaped rotary grinding blade whose outer peripheral surface faces the support surface, the support surface being one end in the axial direction of the rotary grinding blade. Grinding using a grinding apparatus having a first surface on the side and a second surface closer to the rotary grinding blade than the first surface, on the other end side in the axial direction of the rotary grinding blade A second member of the ferrite molded body A supporting step of supporting the ferrite molded body by placing the first member of the ferrite molded body on the second surface so as to face the first surface, and rotationally driving the rotary grinding blade, A step of grinding a portion where the first member and the second member of the ferrite molded body are continuous, and the support means further includes a side wall portion on the side opposite to the second surface of the first surface, The side wall includes an inner surface that is substantially parallel to the shaft end surface of the rotary grinding blade, and the grinding device is disposed such that the inner surface of the side wall is inclined by 2 to 8 degrees with respect to the vertical direction. In the supporting step, the ferrite molded body is supported so that an outer end surface of the second member is in contact with an inner surface of the side wall portion.

According to the process of the present invention, and further comprising a firing step to obtain a ferrite core by firing a ferrite grinding bodies and grinding Grinding method described above.

The grinding apparatus according to the present invention includes a first member and a second member that are formed by press-molding a ferrite granule including a ferrite material and PVA, and that are continuous in the press-molding direction, and the press-molding direction of the second member. A cross-sectional area perpendicular to the press molding direction of the first member is larger than the cross-sectional area of the first member, and the second member is a ferrite molded body having a density 3% to 8% larger than the density of the first member. A grinding apparatus comprising: a support means for supporting by a support surface; and a disk-shaped rotary grinding blade whose outer peripheral surface faces the support surface, wherein the support surface is one end side in the axial direction of the rotary grinding blade. A first surface on the other end side in the axial direction of the rotary grinding blade and a second surface closer to the rotary grinding blade than the first surface, A side wall portion is further provided on the side opposite to the second surface, and the side wall portion is An inner surface of the second surface substantially perpendicular, characterized in that the inner surface of the side wall portions are configured to be inclined 2 ° to 8 ° with respect to the vertical direction.

  The grinding apparatus according to the present invention is characterized in that the inner side surface is inclined by 4 to 6 degrees with respect to the vertical direction.

  According to the present invention, the second member has a density that is 3% to 8% larger than the density of the first member, so that chipping does not occur, and the cracks in the vicinity of the center of the shaft portion of the fired body and the outer end surface of the flange portion The generation of cracks at the outer peripheral ridge can be avoided more reliably, and a ferrite core capable of forming a terminal electrode on one side can be obtained.

  According to the present invention, the first member has a cylindrical shape, and the second member has at least two corners in the axial cross section, so that a grinding molded body having a high degree of freedom can be produced.

  According to the present invention, the second member can be provided with directionality by forming a rectangle having a long side and a short side in the axial section, and can be inserted into the embossed tape as a surface mount component, and the component can be removed from the embossed tape. It is very convenient for taking out and mounting on a substrate.

  According to the present invention, the second member has a shape in which the axial cross section is formed by an arc and a straight line, and while having directionality, the terminal electrode is formed at both corners of the opposite side of the semicircle, thereby reducing the mounting area. can do.

  According to the present invention, in the grinding device, the support surface is on the first surface on one end side in the axial direction of the rotary grinding blade and on the other end side in the axial direction of the rotary grinding blade, and the first surface In addition, since the second surface is closer to the rotary grinding blade, it is possible to grind an object to be ground having a high degree of freedom.

  According to the present invention, the object to be ground can be stably ground by providing the side wall portion in the grinding apparatus.

  According to the present invention, in the grinding apparatus, the inner side surface of the side wall portion is configured to be inclined with respect to the vertical direction. Reliable grinding can be performed while always contacting the second surface, which is the processing reference surface, and the inner surface of the side wall.

  According to the present invention, it is possible to obtain a ferrite magnetic core having a shape capable of easily forming a terminal electrode on one side collar portion at a low cost and with a fast lead time by a press molding process and a centerless processing process, which are excellent in productivity. .

2 is a perspective view showing a ferrite magnetic core according to Embodiment 1. FIG. FIG. 3 is a front view showing a ferrite magnetic core according to the first embodiment. FIG. 3 is a top view showing a ferrite magnetic core according to the first embodiment. 1 is a schematic diagram showing a press molding apparatus according to Embodiment 1. FIG. FIG. 3 is an explanatory diagram schematically showing press forming processing by the press forming apparatus according to Embodiment 1. 3 is a perspective view showing a molded body after press molding according to Embodiment 1. FIG. It is the perspective view which abbreviate | omitted partially which shows the centerless processing machine which concerns on Embodiment 1. FIG. FIG. 3 is a cross-sectional view schematically showing processing of the centerless processing machine according to the first embodiment. 2 is a perspective view showing a drum core molded body after centerless processing according to Embodiment 1. FIG. FIG. 3 is a perspective view showing an inductance element using a drum core fired body in which terminal electrodes are formed on the collar according to the first embodiment. FIG. 3 is a perspective view showing a transformer component using a drum core fired body in which terminal electrodes are formed on the flange according to the first embodiment. 5 is a perspective view showing a ferrite magnetic core according to Embodiment 2. FIG. 6 is a front view showing a ferrite magnetic core according to Embodiment 2. FIG. 6 is a top view showing a ferrite magnetic core according to Embodiment 2. FIG. 5 is a schematic diagram showing a press molding apparatus according to Embodiment 2. FIG. 6 is a top view showing a molding die according to Embodiment 2. FIG. FIG. 6 is an explanatory diagram schematically showing press forming processing by a press forming apparatus according to Embodiment 2. 5 is a perspective view showing a molded body after press molding according to Embodiment 2. FIG. It is a perspective view which shows the inductance element using the drum core baking body by which the terminal electrode was formed in the collar part concerning Embodiment 2. FIG. It is a perspective view which shows the inductance element using the drum core provided with the conventional double-sided circular collar part. It is explanatory drawing which shows the principle of centerless processing typically. It is explanatory drawing which shows the principle of centerless processing typically. It is explanatory drawing which shows typically the principle of the centerless process of a drum core provided with the both-sides square collar part.

Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.
In the following embodiments, an example of producing a soft ferrite drum core exhibiting soft magnetism will be described.

(Embodiment 1)
1 is a perspective view showing a drum core 1 according to the first embodiment, FIG. 2 is a front view showing the drum core 1 according to the first embodiment, and FIG. 3 is a top view showing the drum core 1 according to the first embodiment. . As shown in the figure, the drum core 1 (ferrite magnetic core) includes a circular flange portion 11, a square flange portion 12, and a shaft portion 13 that connects the circular flange portion 11 and the square flange portion 12.

  In order to manufacture the drum core 1 according to Embodiment 1, each raw material powder of ferrite material is weighed, pure water is added and mixed with an attritor, a binder is added to the mixed slurry, and then a spray dryer Dry with (spray dryer). The obtained mixed powder granules are placed in an alumina box and calcined, and pure water is added to the calcined granules and pulverized with an attritor. A binder was added to the resulting slurry and dried with a spray dryer to obtain ferrite granules 10. After filling the granule 10 of ferrite into the molding die 20 of the press molding apparatus 2 as shown in FIGS. 4 and 5, the upper and lower punch portions 21 and 22 are respectively lowered and pushed up into the molding die 20. The ferrite molded body 3 shown in FIG.

  The manufactured ferrite molded body 3 was centerless processed with a centerless processing machine 4 as shown in FIGS. As shown in the perspective view of FIG. 9, the obtained ferrite grinding body 5 includes a circular flange 51, a square flange 52, and a shaft 53 that connects them. Next, the ferrite ground body 5 was fired to obtain a drum core 1 having a fired body as shown in FIG.

  Hereinafter, the details of the press molding process of the first embodiment will be described. 4 is a schematic diagram showing the press molding apparatus according to the first embodiment, FIG. 5 is an explanatory diagram schematically showing press molding processing by the press molding apparatus according to the first embodiment, and FIG. 6 is according to the first embodiment. It is a perspective view which shows the molded object after press molding. The press molding apparatus 2 includes a molding die 20 having an inner wall surface constituted by a hollow square cylindrical upper wall surface 20a, a cylindrical lower wall surface 20b, and a connecting surface 20c for connecting them, and an upper wall surface 20a. A rectangular columnar upper punch portion 21 that is slidably inserted and a columnar lower punch portion 22 that is slidably inserted into the lower wall surface 20b are provided. The press molding apparatus 2 includes a drive unit 23 such as a motor that drives the upper punch unit 21 and the lower punch unit 22, and a drive control unit 24 such as a microcomputer that controls driving by the drive unit 23. The drive control unit 24 includes a descending control unit 241, an ascending control unit 242, an auxiliary descending control unit 243, and the like as functional components.

  In the first embodiment, the cross-sectional area in the direction intersecting the axial direction of the quadrangular columnar upper punch portion 21 is larger than the cross-sectional area in the direction intersecting the axial direction of the cylindrical lower punch portion 22. The hole formed in the molding die 20 has a downward convex shape, and a rectangular columnar upper hole surrounded by an upper wall surface 20a on which the upper punch portion 21 slides and a connecting surface 20c, and a lower punch portion 22 are formed. It is constituted by a columnar prepared hole surrounded by a sliding lower wall surface 20b. The opening cross-sectional area of the upper hole in the direction intersecting the direction in which the upper punch portion 21 advances and retreats is larger than the opening cross-sectional area of the lower hole in the direction intersecting with the direction in which the lower punch portion 22 advances and retreats.

  In order to form the ferrite molded body 3 according to the first embodiment with such a press molding apparatus 2, first, in the first step as shown in FIG. The upper punch portion 21 is disposed at a lower end surface 21a above the upper end surface of the upper punch portion 20 and is further disposed at an upper end surface 22a of the lower punch portion 22 above the lower end surface of the molding die 20. The part 21 and the lower punch part 22 are driven. Thereby, the molding die 20 and the lower punch portion 22 form an accommodating portion for filling the ferrite granules 10. And the granule 10 of ferrite is filled in the accommodating part to the same height as the upper end face of the molding die 20.

  Next, in the second step shown in FIG. 5B, the drive unit 23 drives the upper punch unit 21 and lowers the upper punch unit 21. At this time, the lowering control unit 241 uses the initial position of the upper end surface 22a of the lower punch unit 22 as a high reference surface, and lowers the lower end surface 21a of the upper punch unit 21 to the first height h1 from the reference surface. Thus, the drive of the drive part 23 is controlled. Thus, the lower end surface 21a of the upper punch portion 21 is brought into contact with the surface of the ferrite granule 10, and a pressing force is uniformly applied to the ferrite granule 10 filled in the accommodating portion.

  Next, in the third step shown in FIG. 5C, the drive unit 23 drives the lower punch unit 22 to raise the lower punch unit 22. At this time, the ascending control unit 242 raises the upper end surface 22a of the lower punch unit 22 to the third height h3 from the reference surface, and the ferrite filled in the accommodation unit with the upper end surface 22a of the lower punch unit 22 The drive of the drive unit 23 is controlled so as to apply a pressing force to the granules 10. As a result, a part of the ferrite granules 10 on the upper end surface 22a of the lower punch portion 22 is moved to the space formed by the lower surface 21a of the upper punch portion 21 and the connecting surface 20c of the molding die, that is, more loaded. Flows to the less side.

  Further, in the fourth step shown in FIG. 5D, the drive unit 23 drives the upper punch unit 21 and lowers the upper punch unit 21. At this time, the auxiliary lowering control unit 243 drives the driving unit 23 so as to lower the lower end surface 21a of the upper punch unit 21 to a second height h2 that is substantially lower than the first height h1 from the reference surface. To control. A pressing force is applied to the ferrite granules 10 filled in the accommodating portion at the lower end surface 21a of the upper punch portion 21 so as to crush them. As a result, the ferrite granules 10 filled in the accommodating portion do not flow but are crushed and tightly coupled. As shown in FIG. 6, a ferrite molded body 3 including a cylindrical portion 31 and a quadrangular prism portion 32 having a higher density than the cylindrical portion 31 was manufactured. The manufactured ferrite molded body 3 is transmitted to a centerless processing machine 4 described later.

  Regarding the density of the cylindrical portion 31 and the rectangular column portion 32 of the ferrite molded body 3 manufactured in this way, the inventor adjusts the pressure or stroke of the upper and lower punch portions during the press molding, and the cylindrical portion 31 and the rectangular column portion. A plurality of ferrite molded bodies 3 having a density different from that of 32 were prepared, and a collar portion was formed by centerless grinding, and then the appearance of the ferrite ground body 5 was evaluated. Further, the ferrite ground body 5 was fired, and the dimensions after firing were evaluated. As a result, it was found that in the ferrite molded body 3 according to the first embodiment, it is preferable that the quadrangular column part 32 has a density that is 3% to 8% greater than the density of the cylindrical part 31. When the density of the rectangular column portion 32 is 3% to 8% larger than the density of the cylindrical portion 31, there is no occurrence of a chipping of the rectangular flange portion of the ferrite grinding body 5. In the case of less than 3%, in the appearance after the centerless processing, many chips are observed at the end portion of the substantially rectangular ridge part, and it cannot be produced with a high pass rate. If it exceeds 8%, the difference between the shrinkage ratios becomes larger when the circular collar part and the square collar part are fired and shrunk, so cracks are caused by the difference in shrinkage behavior near the interface of the cylindrical part and the substantially quadrangular prism part. Will occur. In order to prevent chipping and to more reliably avoid the occurrence of cracks in the vicinity of each interface of the fired body, 5% to 7% is more preferable.

  Next, details of the centerless machining process of the first embodiment will be described. 7 is a partially omitted perspective view showing the centerless processing machine according to the first embodiment, FIG. 8 is a cross-sectional view schematically showing the processing of the centerless processing machine according to the first embodiment, and FIG. 9 is the embodiment. 1 is a perspective view showing a drum core molded body after centerless processing according to FIG. As shown in FIGS. 7 and 8, the centerless processing machine (grinding device) 4 of the first embodiment is a grinding blade attached to a rotating shaft 41 a that is linked to a motor shaft (not shown) of an electric motor. 41, a supply chute 42 that transmits the ferrite molded body 3, and a guide device 43 that faces the grinding blade 41 and guides the ferrite molded body 3 transmitted from the supply chute 42. The guide device 43 is disposed on a disc-shaped support portion 46, a plurality of protrusions 44 that are spaced apart from each other by an appropriate length on the outer periphery of the support portion 46, and on both end surfaces of the support portion 46. Side wall portions 47 and 48 provided perpendicular to the outer peripheral surface of the outer wall surface (in FIG. 7, illustration of the side wall portion 47 is omitted). Further, the support portion 46 includes a first outer peripheral surface 46a and a stepped outer peripheral shape that includes the second outer peripheral surface 46b that is continuous with the first outer peripheral surface 46a in the axial direction and is larger than the first outer peripheral surface 46a. Have The step between the second outer peripheral surface 46 b and the first outer peripheral surface 46 a is formed to be larger than the portion where the quadrangular column portion 32 of the ferrite molded body 3 to be processed projects from the cylindrical portion 31. The plurality of protrusions 44 are arranged on the second outer peripheral surface 46b, and the space formed by the protrusions 44 and 44 adjacent in the circumferential direction stably grinds the ferrite molded body 3 transmitted from the supply chute 42. A holding portion 45 is formed to hold as described above. Further, the centerless processing machine 4 is configured such that the inner surface of the side wall 47 on the first outer peripheral surface 46a side is inclined with respect to the vertical direction.

  When the centerless processing machine 4 performs centerless processing of the ferrite molded body 3, as shown in FIG. 8, the ferrite molded body 3 fed out from the press molding apparatus 2 has a rectangular column portion 32 having a first outer periphery of the guide apparatus 43. The surface 46a and the cylindrical portion 31 are sequentially fed to the outer periphery of the guide device 43 through the supply chute 42 so as to correspond to the second outer peripheral surface 46b. The guide device 43 is rotationally driven in the direction of arrow A, and each ferrite compact 3 to be supplied is held by a holding portion 45 between a plurality of protrusions 44 and 44 mounted on the outer peripheral surface of the rotating guide device 43. Are transmitted one by one. The outer peripheral surface 31b of the cylindrical portion 31 is always in contact with the second outer peripheral surface 46b, the outer end surface 32a of the quadrangular prism portion 32 is always in contact with the inner side surface 47a of the side wall portion 47, and the outer end surface 31a of the cylindrical portion 31 is The inner surface 48a and the outer peripheral surface 32b of the quadrangular prism portion 32 are held by the holding portion 45 so as to face the first outer peripheral surface 46a with a gap. The held ferrite molded body 3 is sequentially fed toward the minimum gap portion between the guide device 43 and the grinding blade 41 while being regulated by the protrusion 44.

  The grinding blade 41 is rotationally driven at high speed, and when the ferrite molded body 3 passes through the minimum gap portion between the guide device 43 and the grinding blade 41, the grinding blade 41 moves the ferrite molded body 3 around the outer periphery of the cylindrical portion 31. The surface 31 b is rotated while being always in contact with the second outer peripheral surface 46 b and the outer end surface 32 a of the quadrangular column 32 is in contact with the inner surface 47 a of the side wall 47. The rotating ferrite molded body 3 is ground by the grinding blade 41. The width of the grinding blade 41 is smaller than the overall length of the ferrite molded body 3 in the axial direction, and the intermediate portion of the ferrite molded body 3 in the axial direction is cut by the width of the grinding blade 41 to form a circular flange as shown in FIG. 51, a drum-shaped ferrite grinding body 5 having a square flange 52 and a shaft 53 connecting them. The ferrite grinding body 5 processed into the drum shape is sequentially discharged by the rotation guide of the guide device 43.

  Here, in the first embodiment, the centerless processing machine 4 is arranged so that the inner side surface 47a of the side wall 47 on the first outer peripheral surface 46a side is inclined downward with respect to the vertical direction. Further, in the ferrite molded body 3, the quadrangular column portion 32 has a higher density than the columnar portion 31 and is configured to protrude from the columnar portion 31, so that the quadrangular column portion 32 is heavier than the columnar portion 31. large. Therefore, as described above, the outer peripheral surface 31b of the cylindrical portion 31 is held by the holding portion 45 so that the outer peripheral surface 46b is always in contact with the second outer peripheral surface 46b, and the outer end surface 32a of the rectangular column portion 32 is always in contact with the inner side surface 47a of the side wall portion 47. In this case, in the ferrite molded body 3, the center of gravity of the rectangular column part 32 is set lower than the center of gravity of the cylindrical part 31. Further, the step between the second outer peripheral surface 46 b and the first outer peripheral surface 46 a is larger than the portion where the quadrangular prism portion 32 projects from the cylindrical portion 31, and the outer end surface 31 a of the cylindrical portion 31 is within the side wall portion 48. It faces the side surface 48a with a gap. Thereby, the ferrite compact 3 can be stably rotated and moved during the centerless processing.

  In the first embodiment, it is preferable that the inner side surface 47a of the side wall 47 on the first outer peripheral surface 46a side is inclined by 2 to 8 degrees with respect to the vertical direction. If it is less than 2 degrees, the contact between the outer peripheral surface 31b of the cylindrical portion 31 and the second outer peripheral surface 46b is unstable, and the grinding accuracy is lowered. If the angle exceeds 8 degrees, the friction caused by the contact between the outer end surface 32a of the quadrangular column 32 and the inner surface 47a of the side wall portion 47 is large, and the rotational movement of the molded body becomes unsmooth and stops in the middle. Will not be made all around. More preferably, it is 4 to 6 degrees.

  FIG. 10 is a perspective view showing an inductance element using a drum core fired body in which terminal electrodes are formed on the flange according to the first embodiment. The ferrite ground body 5 was fired as described above to obtain the drum core 1 of the fired body of FIG. Furthermore, the terminal electrodes 16 and 16 are formed in the adjacent two corners of the substantially quadrangular collar portion of the drum core 1 of the fired body obtained, and the insulation-coated conductive wire 15 is wound around the shaft portion 13 between the both side collar portions. Both ends were soldered to the two terminal electrodes 16 and 16 with solder, and an inductance element as shown in FIG. 10 was obtained.

  FIG. 11 is a perspective view showing a transformer component using a drum core fired body in which terminal electrodes are formed on the flange according to the first embodiment. The ferrite ground body 5 was fired as described above to obtain the drum core 1 of the fired body of FIG. Further, terminal electrodes 16, 16, 16, 16 are formed at the four corners of the substantially rectangular collar portion of the drum core 1 of the fired body, and a pair of insulating coated conductors 15 are formed on the shaft portion 13 between the both side collar portions. Winding and soldering both ends of each conductive wire to the four terminal electrodes 16, 16, 16, 16 adjacent to each other with solder, and in the space sandwiched between the circular flange portion 11 and the square flange portion 12, A transformer component as shown in FIG. 11 was obtained by filling a heat-resistant resin in which powder was dispersed and mixed.

(Embodiment 2)
Next, Embodiment 2 of the present invention will be described with reference to FIGS.
12 is a perspective view showing a ferrite core according to the second embodiment, FIG. 13 is a front view showing the ferrite core according to the second embodiment, and FIG. 14 is a top view showing the ferrite core according to the second embodiment. The ferrite magnetic core 6 according to the second embodiment includes a circular flange 61, a semicircular rectangular flange 62, which is a combined shape of a square and a circle, instead of the configuration including the rectangular flange 12 of the first embodiment, It is set as the structure provided with the axial part 63 which connects. The press molding device 7 and the press molding process are also different from those in the first embodiment. Other than that, the second embodiment is basically configured in the same manner as the first embodiment, and therefore, a duplicate description is omitted.

  15 is a schematic diagram showing a press molding apparatus according to the second embodiment, FIG. 16 is a top view showing a molding die according to the second embodiment, and FIG. 17 is a press molding process by the press molding apparatus according to the second embodiment. FIG. 18 is a perspective view showing a molded body after press molding according to the second embodiment. The press molding apparatus 7 shown in FIG. 15 includes a hollow semicircular substantially square cylindrical upper wall surface 70a corresponding to a ferrite molded body 60 to be molded, a cylindrical lower wall surface 70b, and a connecting surface for connecting them. A molding die 70 having an inner wall surface 70c, a semi-circular substantially quadrangular prism-shaped upper punch portion 71 slidably inserted into the upper wall surface 70a, and a circle slidably inserted into the lower wall surface 70b. A columnar lower punch portion 72 is provided. The press molding apparatus 7 includes a drive unit 73 such as a motor that drives the upper punch unit 71 and the lower punch unit 72 and a drive control unit 74 such as a microcomputer that controls driving by the drive unit 73. The drive control unit 74 includes a descending control unit 741, an ascending control unit 742, an auxiliary descending control unit 743, and the like as functional components.

  As shown in FIGS. 15 and 16, in the molding die 70, the cross section in the direction intersecting the axial direction of the semicircular substantially quadrangular columnar upper punch portion 71 intersects the axial direction of the cylindrical lower punch portion 72. Larger than the cross-sectional area in the direction. The hole formed in the molding die 70 has a downwardly convex shape, and is a semicircular quadrangular columnar upper hole surrounded by an upper wall surface 70a on which the upper punch portion 71 slides and a connecting surface 70c, and a lower punch portion. It is constituted by a cylindrical prepared hole surrounded by a lower wall surface 70b on which 72 slides. The semicircular quadrangular columnar upper hole projects from the cylindrical pilot hole on one side. The opening cross-sectional area of the upper hole in the direction intersecting the direction in which the upper punch portion 71 advances and retreats is larger than the opening cross-sectional area of the lower hole in the direction intersecting with the direction in which the lower punch portion 72 advances and retreats.

  In order to manufacture the ferrite molded body according to the second embodiment by the press molding apparatus 7 as described above, first, in the first step as shown in FIG. The upper punch surface 71a is disposed above the upper end surface of the upper punch portion 71, and the upper punch surface 72a is disposed above the lower end surface of the molding die 70. The part 71 and the lower punch part 72 are driven. In this way, a housing part for filling the ferrite granules 10 is formed by the molding die 70 and the lower punch part 72. Then, the ferrite granules 10 are filled in the accommodating portion to the same height as the upper end surface of the molding die 70.

  Next, in the second step shown in FIG. 17B, the drive unit 73 drives the upper punch unit 71 and lowers the upper punch unit 71. At this time, the lowering control unit 741 uses the initial position of the upper end surface 72a of the lower punch unit 72 as a high reference surface, and lowers the lower end surface 71a of the upper punch unit 71 to the first height h1 from the reference surface. Thus, the drive of the drive part 73 is controlled. Thus, the lower end surface 71a of the upper punch portion 71 is brought into contact with the surface of the ferrite granule 10, so that a pressing force is uniformly applied to the ferrite granule 10 filled in the accommodating portion.

  Next, in the third step shown in FIG. 17C, the drive unit 73 drives the lower punch unit 72 to raise the lower punch unit 72. At this time, the ascending control unit 742 raises the upper end surface 72a of the lower punch unit 72 to the third height h3 from the reference surface, and the ferrite filled in the housing unit with the upper end surface 72a of the lower punch unit 72. The drive of the drive unit 73 is controlled so as to apply a pressing force to the granules 10 to crush them. As a result, the ferrite granule 10 accommodated in the accommodating portion is crushed and tightly coupled.

  Further, in the fourth step shown in FIG. 17D, the drive unit 73 drives the upper punch unit 71 and lowers the upper punch unit 71. At this time, the auxiliary lowering control unit 743 drives the driving unit 73 to lower the lower end surface 71a of the upper punch unit 71 to a second height h2 that is substantially lower than the first height h1 from the reference surface. Control. A pressing force is applied to the ferrite granules 10 filled in the accommodating portion at the lower end surface 71 a of the upper punch portion 71. In this case, since the ferrite granule 10 has already been crushed and bonded, the ferrite granule 10 filled in the accommodating portion does not flow. As a result, the bonded body of the ferrite granules 10 located in the space formed by the lower end surface 71a of the upper punch portion 71 and the connecting surface 70c of the molding die is further pressed and further tightly coupled. As a result, as shown in FIG. 18, a ferrite molded body 60 including a cylindrical portion and a semicircular substantially quadrangular prism portion whose density is higher than that of the cylindrical portion was manufactured.

  As in the first embodiment, the density of the cylindrical portion and the semicircular substantially quadrangular prism portion of the ferrite molded body 60 manufactured in this way is 3% to 8% higher than the density of the cylindrical portion. It is preferable to have. 5% or more and 7% or less are more preferable.

  The manufactured ferrite molded body 60 was centerless processed and fired in the same manner as in Embodiment 1 to obtain a ferrite magnetic core 6 as shown in FIG. The ferrite magnetic core 6 is formed with a terminal electrode 16 in a semicircular substantially quadrangular ridge, winding an insulation-coated conductive wire between both ridges, and soldering both ends of the conductive wire to the two terminal electrodes 16 with solder. Further, an inductance element as shown in FIG. 19 was obtained by filling a space between both flange portions 61 and 62 with a heat resistant resin in which ferrite powder was dispersed and mixed.

  The ferrite magnetic core 6 according to the second embodiment has a configuration including a semicircular quadrangular flange 62 that is a combined shape of a square and a circle, instead of the configuration including the quadrangular flange 12 of the first embodiment. Considering that the difference in the axial cross-sectional area between the semicircular rectangular flange 62 and the circular flange is smaller than the difference in the axial cross-sectional area between the rectangular flange 12 and the circular flange 11 of the first embodiment. And although the above-mentioned press molding process is employ | adopted, it is needless to say that not only this but the press molding process similar to Embodiment 1 may be employ | adopted.

  The density of the ferrite compact is presumed to be very complicated in the manner in which ferrite granules are filled into the mold during pressing and the behavior such as flow and deformation due to pressure. It is preferable to adopt an appropriate molding process by evaluating the shape of the molded body / fired body, variation in shrinkage during firing, etc., using the upper and lower punch conditions as parameters according to the shape of each molded body.

Hereinafter, the present invention will be described in detail based on examples.
Example 1
As a ferrite material, each raw material powder was weighed so as to have a composition of mol%, Fe ₂ O ₃ : 47, NiO: 23, CuO: 5, ZnO: 25, and pure water was added and mixed by an attritor. . After 1% of PVA was added to the mixed slurry with respect to the weight of the ferrite material, it was dried with a spray dryer. The obtained mixed powder granules were put into an alumina box and calcined by holding them in the atmosphere at a maximum temperature of 900 ° C. for 2 hours. Pure water was added to the calcined granules and pulverized with an attritor. To this slurry, 2% of PVA was added with respect to the weight of the ferrite material, and dried with a spray dryer to obtain granules. The particle size of the granules was about 100 μm.

  After filling the obtained granules into a molding die 20 of a press molding apparatus as shown in FIG. 4 in which a molded body in which a cylindrical portion and a substantially square quadrangular prism portion are combined is obtained, the process described in the first embodiment And a ferrite molded body was obtained. The shape of the molded body is such that the diameter of a circular ridge or the length of one side of a substantially rectangular ridge is about 3 mm and the height is about 1 mm.

  First, 10 ferrite compacts were produced, the cylindrical part and the quadrangular prism part were separated with a cutter knife, the respective weights were measured with an electronic balance, the size was measured with a micrometer, and the compact density was calculated. The results are shown in Table 1. It can be seen that the density of the quadrangular prism portion is in the range of 3% to 8% larger than that of the cylindrical portion.

  Next, 1000 ferrite compacts were produced under the above conditions. The processing mechanism portion of the centerless processing machine 4 shown in FIGS. 7 and 8 is manufactured according to the shape in advance, and the inner side surface 47a of the side wall portion 47 is set to be inclined at an angle of 5 degrees in the vertical direction.

  1000 pieces of the produced ferrite compacts were processed by the centerless processing machine 4 equipped with the mechanism. The thickness of the grinding blade was 490 μm, and the distance between both side flanges was about 510 μm. A drum core molded body having a circular collar portion and a substantially square collar portion as shown in FIG. 9 was produced. When the appearance of 1000 drum core molded bodies was evaluated, there was no chipping defect.

  Next, 1000 drum core compacts were fired in the air at a maximum temperature of 1100 ° C. for 2 hours to obtain a drum core fired body. The firing shrinkage rate was about 16%. The appearance inspection and dimensional inspection of the fired body were performed to confirm that there was no problem.

  About 50 of the obtained drum core fired bodies, an insulating coated conductor wire having a diameter of 100 μm is wound 12 times between the flanges on both sides, and an LCR meter 4284A manufactured by HP is used to perform inductance and DC superposition characteristics at a frequency of 100 kHz. Was evaluated, and it was confirmed that the intended characteristics as an inductance element were obtained.

(Example 2)
About 50 of the drum core fired bodies obtained in Example 1, the Ag paste was applied and dried so as to be continuous from the outer surface of the collar part to the inner surface through the side surface by dipping in two adjacent corners of the substantially square collar part. Thereafter, it was fired by holding at 600 ° C. for 20 minutes in the air. Next, Ni and Sn plating films were applied on the Ag electrodes by electrolytic barrel plating to form terminal electrodes. Next, an insulating coated conductor wire having a diameter of 100 μm was wound 12 times between both side flanges, and both ends of the conductor wire were soldered to the two terminal electrodes with a high melting point solder to obtain an inductance element. The obtained inductance element was fabricated in advance, mounted on a printed circuit board for evaluation in which low melting point solder was printed on the connection portion with the terminal electrode portion, and soldered by a reflow apparatus. The inductance element was evaluated through the evaluation printed board, and it was confirmed that the intended characteristics were obtained.

(Example 3)
As a press-molding die, as shown in FIG. 6, a press-molding die is obtained in which a ferrite molded body 3 is obtained, in which one side is a cylinder and the other side is a rectangular column having a cross section having a long side and a short side. 2 were used, and 1000 drum core fired bodies were produced under the same conditions as in Example 1. The obtained drum core fired body includes a circular flange 11 and a substantially rectangular flange 12 as shown in FIG. Next, after applying and drying Ag paste on the four corners of the substantially rectangular ridge part by dip method so as to continue from the outer surface of the heel part to the inner surface through the side surface, terminal electrodes were formed under the same conditions as in Example 2. Next, after winding 70 μm diameter insulation coated wire between both side collars 5 times, combining another insulation coated wire and winding 2 times 5 times, then only the first insulation coated wire wound Was wound five more times.

  Next, both ends of the conductor with the larger number of windings are connected to terminal electrodes at both corners of one short side of a substantially rectangular shape, and both ends of the conductor with the smaller number of windings are connected to both ends of the short side facing the short side. Each corner terminal electrode was soldered with a high melting point solder. Furthermore, a transformer part as shown in FIG. 11 is obtained by filling a space sandwiched between the surfaces of the substantially rectangular collar part and the circular collar part extending the outer circle with a heat resistant resin in which ferrite powder is dispersed and mixed. Obtained. The obtained transformer component was mounted on a printed circuit board for evaluation in which low melting point solder was printed on a connection portion with the terminal electrode portion prepared in advance, and soldered by a reflow apparatus. Transformer components were evaluated via a printed circuit board for evaluation, and it was confirmed that the intended characteristics were obtained. Moreover, about the leakage magnetic flux, it compared with what was not what was filled with the heat resistant resin by which the ferrite powder was disperse-mixed, and it confirmed that leakage magnetic flux was less by filling with the said resin.

Example 4
As a press molding die, as shown in FIG. 18, a press molding die in which a ferrite molded body 60 in which one side is a cylinder and the other side is a semi-cylinder and a substantially square column is obtained is used. 1000 drum core fired bodies were produced under the same conditions as in Example 1. The obtained drum core fired body is provided with a circular collar part and a collar part formed by combining a semicircle and a substantially square shape.

  About 50 of the obtained drum core fired bodies, Ag paste was applied and dried in two corners by a dip method in a shape of a substantially semicircle and a substantially square shape so as to continue from the outer surface of the buttock to the inner surface through the side surface. Thereafter, an inductance element was obtained under the same conditions as in Example 2. The obtained inductance element was fabricated in advance, mounted on a printed circuit board for evaluation in which low melting point solder was printed on the connection portion with the terminal electrode portion, and soldered by a reflow apparatus. The inductance element was evaluated through the evaluation printed board, and it was confirmed that the intended characteristics were obtained. In addition, the mounting area is about 20% smaller than in the case of Example 2 and the mounting flange has a shape that combines a semicircle and a substantially square shape. Therefore, when inserting into the embossed tape used for surface mounting, The directionality could be easily recognized by a feeder or the like.

(Comparative Examples 1-3)
As Comparative Example 1, the press conditions described in Example 1 were changed, and sample Nos. As shown in 11, 12, and 13, as a condition that the density of the molded body of the quadrangular column part exceeds 8% as compared with the cylindrical part, 30 molded bodies were produced under each condition. After firing, appearance evaluation was performed. In the condition of 11, the sample No. In the condition of 12, the sample number is 9 out of 30. Under 13 conditions, cracks were observed in the vicinity of the boundary of the cylindrical portion and the quadrangular column portion in 13 out of 30 pieces.

  As Comparative Example 2, the press conditions described in Example 1 were changed, and Sample No. As shown in 14, 15, and 16, as a condition that the density of the molded body of the quadrangular column part is less than 3% compared to the cylindrical part, 30 molded bodies were produced under each condition, and the appearance was evaluated. Sample No. No. 14 is 16 out of 30 and sample no. 15 is 10 out of 30, and sample no. In No. 16, chipping of a substantially rectangular ridge portion of the molded body was remarkably observed in 9 out of 30 pieces.

  As Comparative Example 3, the press conditions described in Example 1 were changed, and sample Nos. 17, 18, and 19, the density of the molded body of the quadrangular column portion is less than 3% compared to the cylindrical portion, and the density is As the conditions of a comparatively high density and approximately the same as the density of the substantially quadrangular prisms 11 to 13, 30 molded bodies were produced under each condition. After firing, appearance evaluation was performed. In the condition of 17, the sample No. Under the condition of 18, the sample No. Under 19 conditions, cracks were observed on the outer end surface of the cylindrical portion and the ridge portion on the outer periphery of 10 out of 30 pieces.

(Examples 5 to 11, Comparative Examples 4 and 5)
As Examples 5 to 11 and Comparative Examples 4 and 5, in the processing mechanism portion of the centerless processing machine 4 of the first embodiment, as shown in Table 3, the inclination angle is 0 degree (Comparative Example 4), 2 degrees (Implementation) Example 5) 3 degrees (Example 6) 4 degrees (Example 7) 5 degrees (Example 8) 6 degrees (Example 9) 7 degrees (Example 10) 8 degrees (Example 11) ) At 10 degrees (Comparative Example 5), 30 ferrite molded bodies obtained in Example 1 were each processed centerlessly to form a collar portion. For each of these 30 samples, the thickness of the substantially rectangular ridge and the thickness of the circular ridge of the processed product were measured with a projector, and 3σ was calculated as an index of thickness variation. At an angle of 2 to 8 degrees, 3σ is approximately 19 μm or less as the thickness of the substantially rectangular ridge, and 25 μm or less as the thickness of the circular ridge, and is particularly smaller at 15 to 21 μm or less at angles of 4 to 6 degrees, respectively. High processing accuracy. On the other hand, at an angle of 10 degrees, the rotational movement of the formed body stopped in the middle of processing, and cutting could not be performed over the entire circumference. In addition, the average thickness of both side ridges was about 300 μm. At an angle of 0 °, it can be estimated that the grinding position varies because the contact of the outer peripheral surface of the cylindrical portion with the processing reference surface is unstable.

  As mentioned above, although embodiment of this invention was explained in full detail, this invention is not limited to the said embodiment, A various deformation | transformation implementation is possible within the range of the summary of this invention.

  For example, in the first and second embodiments, a molded body in which one side is a cylinder and the other side is a square column, and a molded body in which one side is a cylinder and the other side is a semi-cylinder and a substantially square column are described as examples. However, the present invention is not limited to this, and a molded body having another shape may be applied. In short, if approximately half of the height of the molded body is a cylindrical shape, the remaining half of the molded body is not limited to a substantially rectangular prism in principle, but can be a substantially polygonal shape by utilizing the outer peripheral surface of the cylinder. It is possible to produce a molded body having a high degree of freedom including.

  The cylinder has a circle diameter and a column height, and the magnitude relationship between the diameter and the height is not questioned. Accordingly, the circular plate is also included in the cylinder. Similarly, a substantially polygonal column including a substantially quadrangular column does not ask the magnitude relation between the length of the side of the substantially polygon and the length of the column. Therefore, the substantially polygonal plate is also included in the substantially polygonal column. Further, the substantially polygon does not mean only a substantially regular polygon. Here, the term “substantially used in a substantially quadrangular shape or a substantially polygonal shape” means that all or part of each corner portion includes a shape that is chamfered into a linear shape or an arc shape.

  Moreover, if a centerless process is possible, a substantially cylinder means not only a cylinder but the shape which pinched | interposed the elliptic cylinder and the rectangular parallelepiped with the half cylinder.

  In addition, the tilting angle at the time of centerless processing may be such that the outer peripheral surface of the cylinder and the outer surface of the polygonal column are always brought into contact with the processing reference surface using gravity.

In the grinding device, the inner surface of the side wall 47 is configured to be perpendicular to the second outer peripheral surface 46b . In order to be able to perform centerless processing , it is necessary to be substantially vertical .

  The disclosed embodiments should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1,6 drum core (ferrite core)
2,7 Press molding equipment 20,70 Mold 20a Upper wall surface (upper mold)
20b Lower wall surface (lower mold)
21, 71 Upper punch part 22, 72 Lower punch part 21a, 71a Lower end face 22a, 72a Upper end face 241, 741 Lowering control part 242, 742 Ascending control part 243, 743 Auxiliary lowering control part 3 Ferrite compact 31 Cylindrical part (first 1 member)
32 Square column (second member)
4 Centerless processing machine (grinding equipment)
41 Grinding blade 43 Guide device (support means)
46 Supporting part (supporting surface)
46a First outer peripheral surface (first surface)
46b Second outer peripheral surface (second surface)
47 Side wall part 47a Inner side surface 5 Ferrite grinding body 53 Shaft part

Claims (10)

The ferrite granules comprising a ferrite material and PVA becomes by press molding, and a first member and a second member connected to the press-forming direction, the cross-sectional area perpendicular to the press-forming direction of the second member, the A ferrite molded body having a density larger than a cross-sectional area perpendicular to the press molding direction of the first member, and the second member having a density 3% to 8% larger than the density of the first member, and the first member and the first member A ferrite ground body obtained by grinding so that a cross-sectional area perpendicular to the press molding direction of a portion connecting two members is smaller than a cross-sectional area perpendicular to the press molding direction of the first member. The first member has a disk shape,
The ferrite ground body according to claim 1, wherein a cross section of the second member has at least two corners. The ferrite ground body according to claim 1, wherein the second member has a square plate shape. The ferrite ground body according to claim 3, wherein the second member has a rectangular cross section. 3. The ferrite ground body according to claim 1, wherein a cross section of the second member has a circular arc shape and a straight line shape. A ferrite core obtained by firing the ferrite ground body according to any one of claims 1 to 5 . A ferrite granule containing a ferrite material and PVA is press-molded, and has a first member and a second member continuous in the press-molding direction, and a cross-sectional area perpendicular to the press-molding direction of the second member is A ferrite molded body having a density larger than the cross-sectional area perpendicular to the press molding direction of the first member and the second member having a density of 3% to 8% larger than the density of the first member is supported on the ferrite molded body. And a disk-shaped rotary grinding blade whose outer peripheral surface faces the support surface, and the support surface is a first surface on one end side in the axial direction of the rotary grinding blade. A method of grinding using a grinding device that is on the other end side in the axial direction of the rotary grinding blade and has a second surface closer to the rotary grinding blade than the first surface,
A supporting step of supporting the ferrite compact by placing the first member of the ferrite compact on the second surface such that the second member of the ferrite compact faces the first surface;
Rotating the rotary grinding blade to grind a portion where the first member and the second member of the ferrite compact are continuous, and
The support means further includes a side wall on the opposite side of the first surface to the second surface,
The side wall includes an inner surface substantially parallel to the shaft end surface of the rotary grinding blade,
The grinding device is arranged such that the inner surface of the side wall portion is inclined by 2 to 8 degrees with respect to the vertical direction,
In the supporting step, the ferrite molded body is supported so that an outer end surface of the second member is in contact with an inner surface of the side wall portion. A manufacturing method further comprising a firing step of firing the ferrite ground body ground by the grinding method according to claim 7 to obtain a ferrite magnetic core. A ferrite granule containing a ferrite material and PVA is press-molded, and has a first member and a second member continuous in the press-molding direction, and a cross-sectional area perpendicular to the press-molding direction of the second member is Support means for supporting a ferrite molded body having a density larger than a cross-sectional area perpendicular to the press molding direction of the first member and having a density of 3% to 8% larger than the density of the first member on a support surface. And a disc-shaped rotary grinding blade with an outer peripheral surface facing the support surface,
The support surface is a first surface on one end side in the axial direction of the rotary grinding blade;
A second surface on the other end side in the axial direction of the rotary grinding blade, and closer to the rotary grinding blade than the first surface;
A side wall on the opposite side of the first surface from the second surface;
The side wall includes an inner surface that is substantially perpendicular to the second surface,
A grinding apparatus characterized in that an inner surface of the side wall portion is inclined by 2 to 8 degrees with respect to a vertical direction. The grinding apparatus according to claim 9 , wherein the inner surface is configured to be inclined by 4 to 6 degrees with respect to a vertical direction.

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