JP2012033673A - Magnetic element and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the removal of attachments generated in a place upper than the magnetic slurry liquid surface after casting.SOLUTION: A magnetic element compact is obtained from using a cast having a flat part configured so that an inner diameter in the position farther from the bottom face of the cast than a reference surface is larger than an inner diameter in the position closer to the bottom face of the cast than the reference surface including the reference surface when the reference surface is the position closer to the bottom of the cast than the liquid surface into which a magnetic slurry is to be cast and from using a lid member to form a thin wall part by engaging with the cast. A magnetic element is obtained by damaging and separating at least a part of the thin wall part from the magnetic element compact by using a fixture.

Description

  The present invention relates to a resin-molded magnetic element, and more particularly to a magnetic element suitable for a reactor used in a power circuit such as an inverter and energized with a large current, and a manufacturing method thereof.

  As a reactor that is an inductance component used in a power supply circuit, a coil-sealed resin-molded reactor is known in which a soft magnetic powder-filled resin is molded into a predetermined shape in a state of including a winding. For example, in Patent Document 1, a slurry obtained by kneading FeSi powder and a liquid thermosetting epoxy resin with a mixer is poured into a predetermined mold (hereinafter also referred to as casting), and after heating and curing, from the mold A magnetic core (hereinafter also referred to as a magnetic element) obtained by taking out is disclosed.

Japanese Patent Laid-Open No. 2007-200962

  As described above, when pouring a slurry in which soft magnetic powder and liquid thermosetting resin are mixed (hereinafter referred to as magnetic slurry) into a mold having a predetermined shape with windings in advance, vibration is applied as necessary. To improve the fluidity or to degas by depressurization. However, by performing these operations, the liquid level of the cast magnetic slurry fluctuates, and in the mold where the upper part is open, the magnetic slurry liquid level after casting is higher than the inner peripheral surface of the magnetic slurry. It was inevitable that the slurry was temporarily lifted up and the magnetic slurry adhered to the entire inner periphery of the mold in a fillet shape due to surface tension.

  FIG. 9 is a cross-sectional view showing a conventional magnetic element, and shows a state in which the magnetic element 14 is arranged on the mold 2. The magnetic slurry 1 poured into the mold 2 provided with a winding in advance forms a fillet-like deposit 3 on the inner peripheral surface of the mold 2. When the magnetic slurry 1 is heated and cured in this state, the fillet-like deposit 3 is inevitably cured as it is.

  FIG. 10 is a sectional view showing a conventional magnetic element, and shows a state in which a magnetic element 14 formed by curing the magnetic slurry 1 is taken out from the mold 2 shown in FIG.

  The deposit 3 remains on the outer periphery of the upper surface of the magnetic element 14 as a burr rising along the inner peripheral surface of the mold 2 and above the desired liquid level. Since the tip of this deposit 3 is sharp, if it is not treated, it will be injured if the operator touches it. When it is assembled to other parts, it will interfere with the other parts. Since it may cause problems such as adverse effects on properties as a foreign material, it must be removed by grinding or the like. FIG. 11 is a cross-sectional view showing a conventional magnetic element, and shows a state in which the deposit 3 that becomes a burr is removed.

  However, there has also been a problem that the magnetic slurry 1 cured when the deposit 3 is removed is scattered as a powder. For this reason, management man-hours such as dust collection and air blow use for preventing contamination of the magnetic element itself and the surrounding environment, and management man-hours for maintaining the grinding quality have been increased, resulting in a cost increase. Further, a part of the magnetic slurry 1 partially remaining on the inner peripheral surface of the upper part of the mold 2 is sandwiched between the mold 2 and the magnetic element 14 when the magnetic element 14 is extracted from the mold 2, The peripheral surface was damaged, and the life of the mold 2 was reduced.

  An object of the present invention is to provide a magnetic element that facilitates the removal of burrs generated in a magnetic element and does not damage the inner peripheral surface of the mold when the magnetic element is extracted from the mold, and a method for manufacturing the same.

  In order to solve the above-mentioned problem, when the shape of the mold is a position that is slightly closer to the bottom surface of the mold than the liquid surface on which the magnetic slurry is to be cast, a position farther from the bottom surface of the mold than the reference surface ( The inner diameter of the mold (hereinafter also referred to as the upper part of the mold) is configured to be larger than the inner diameter of the position including the reference plane and closer to the bottom surface of the mold than the reference plane (hereinafter also referred to as the lower part of the mold). That is, a step having a flat portion on the inner peripheral surface is formed on the reference surface of the mold. Subsequently, the magnetic slurry is poured slightly above the reference surface, that is, the portion where the flat portion is hidden (the portion having a large inner diameter), and the plate-like lid is placed on the flat portion so as to fit the upper portion of the mold. To do.

  As a result, the magnetic element obtained by heat-curing the magnetic slurry poured into the upper part of the mold slightly from the reference surface has a shape with an outer diameter of the upper surface larger than that of the bottom surface when taken out from the mold. That is, the burr larger than the desired outer diameter of the magnetic element is formed in a shape obtained by extending the upper surface of the magnetic element in the surface direction.

  This magnetic element is placed in a jig that supports only the burr portion protruding on the top surface and supports it in the height direction, and presses the center of the top surface of the magnetic element in the bottom direction to remove the burr and remove the magnetic element. obtain.

  According to the present invention, the magnetic slurry obtained by kneading the soft magnetic powder and the resin is poured into a mold in which a winding is arranged in advance and cured, and then the magnetic material is encapsulated and cured from the mold. A method of manufacturing a magnetic element by taking out slurry, wherein the mold has the mold closer to the reference plane when the position closer to the bottom of the mold than the liquid level to which the magnetic slurry is to be cast is used as the mold. A flat surface parallel to the bottom surface of the mold on the inner peripheral surface is configured such that the inner diameter at a position far from the bottom surface of the mold is larger than the inner diameter of the position including the reference surface and closer to the bottom surface of the mold than the reference surface. A method for manufacturing a magnetic element, characterized in that a bottomed columnar body having a portion is used.

  According to the present invention, after casting the magnetic slurry, a lid member is used that forms a thin portion between the flat portion and the inner peripheral surface in contact with the liquid surface of the magnetic slurry. A method for manufacturing a magnetic element is obtained.

  According to the present invention, after curing the magnetic slurry, from the magnetic element molded body obtained by removing the lid member and the mold, using a jig, destroy at least a part of the thin portion. A method of manufacturing a magnetic element characterized by separating is obtained.

  According to the present invention, the thin portion is supported, and a force is applied in a direction from the top surface to the bottom surface of the magnetic element molded body to separate the magnetic element molded body and the thin portion. A method for manufacturing a magnetic element is obtained.

  According to the present invention, only the thin portion is supported, the bottom surface of the magnetic element molded body is separated from the mounting surface of the jig, and a force is applied in a direction from the top surface to the bottom surface of the magnetic element molded body. Thus, a method of manufacturing a magnetic element is obtained, wherein the magnetic element molded body and the thin portion are separated.

  According to this invention, the said cover member has a protrusion in the part which contact | connects the liquid level of the said magnetic slurry, The manufacturing method of the magnetic element characterized by the above-mentioned is obtained.

  According to the present invention, it is possible to obtain a method of manufacturing a magnetic element, wherein the protrusion is provided at a portion corresponding to the inner periphery of the flat portion.

  According to the present invention, the magnetic slurry obtained by kneading the soft magnetic powder and the resin is poured into a mold in which a winding is arranged in advance and cured, and then the magnetic material is encapsulated and cured from the mold. A magnetic element obtained by removing slurry, and when the mold is used as a reference surface at a position closer to the bottom surface of the mold than the liquid surface to which the magnetic slurry is to be cast, from the bottom surface of the mold. The inner peripheral surface has a flat portion parallel to the bottom surface of the mold, the inner diameter of the far position including the reference surface is larger than the inner diameter of the position closer to the bottom surface of the mold than the reference surface. Using the bottomed columnar body, after casting the magnetic slurry, using the lid member that contacts the liquid surface of the magnetic slurry and forms a thin portion between the flat portion and the inner peripheral surface, the magnetic slurry After curing the lid member and the front Type magnetic element green body obtained by removing, using a jig, the magnetic element is obtained which is characterized by comprising separating by destroying at least a portion of the thin portion.

  According to the present invention, there is obtained a magnetic element characterized in that the surface formed by separating the thin wall portion is composed of the hardened resin fracture surface and the soft magnetic powder surface without grinding marks.

  According to the present invention, in a magnetic element manufactured by casting, burrs generated on the top of the magnetic element can be easily removed without using a method such as grinding, and the inner surface of the mold can be removed when the magnetic element is extracted from the mold. It is possible to provide a magnetic element that does not damage the mold and does not reduce the lifetime of the mold, and a method for manufacturing the same.

It is sectional drawing of the magnetic element by this invention. It is sectional drawing of the magnetic element by this invention. FIG. 3A is a cross-sectional view of a magnetic element according to the present invention, and FIG. 3A shows a state where it is carried by a jig for removing the thin portion, and FIG. 3B shows a state where the thin portion is removed. It is sectional drawing of the other magnetic element by this invention. It is sectional drawing of the other magnetic element by this invention. 6A is a cross-sectional view of a magnetic element according to the present invention. FIG. 6A shows a state where the thin part is carried by a jig for removing the thin part, and FIG. 6B shows a state where the thin part is removed. It is sectional drawing explaining the effect | action of this invention. It is sectional drawing explaining an effect | action to this invention. It is sectional drawing which shows the conventional magnetic element. It is sectional drawing which shows the conventional magnetic element. It is sectional drawing which shows the conventional magnetic element.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a sectional view of a magnetic element according to the present invention, showing a state after casting. The winding 7 is previously arranged on the mold 2 having the flat portion 5 on the inner peripheral portion, and the magnetic slurry 1 is poured to such an extent that the flat portion 5 is hidden. Subsequently, the lid 4 is placed in contact with the liquid surface of the magnetic slurry 1, heated and cured to obtain the magnetic element 14. The magnetic slurry 1 is cured to form a plate-like thin portion in the flat portion 5 in a direction parallel to the bottom surface of the mold 2. In addition, the magnetic slurry 1 also enters the gap between the lid 4 and the mold 2 to form a thin portion in a direction substantially orthogonal to the bottom surface of the mold 2, that is, in a substantially vertical direction. Hereinafter, the plate-like thin portion and the thin portion in the substantially vertical direction are collectively referred to as the thin portion 31.

  In order to take out the magnetic element 14 having the thin portion 31 from the die 2 easily and without being damaged, the tapered portion 21 is formed on the die 2 so that the diameter above the flat portion 5 is larger. preferable. In addition, for the same reason, it is preferable to form a tapered portion 41 on the outer peripheral portion of the lid 4 so as to be loosely fitted to the tapered portion 21.

  Moreover, when pulling out the terminal of the winding 7 from the upper part, it is preferable to have a structure in which a hole is formed in the lid 4 and the terminal of the winding 7 is pulled out from the hole. Also in this case, it is preferable to form a tapered portion so that the diameter of the hole increases toward the bottom surface of the magnetic element 14 for the same reason as described above.

  FIG. 2 is a cross-sectional view of the magnetic element according to the present invention, and shows a state where the magnetic element shown in FIG. 1 is removed from the mold. The outer diameter of the upper surface of the magnetic element 14 is larger than the outer diameter of the bottom surface, and the portion protruding from the upper surface constitutes the thin portion 31.

  FIG. 3A is a cross-sectional view of a magnetic element according to the present invention, and shows a state where the magnetic element is carried by a jig for removing a thin portion. FIG. 3B is a cross-sectional view of the magnetic element according to the present invention, and shows a state where the thin portion is removed.

  The magnetic element 14 is carried only by the thin portion 31 and is arranged on the jig 6 so that the bottom surface of the magnetic element 14 does not contact the surface on which the jig 6 is placed. Subsequently, a force is applied from the upper surface to the bottom surface of the magnetic element 14 to push down the main body of the magnetic element 14. At this time, shear stress and tensile stress are generated between the main body of the magnetic element 14 and the thin portion 31, and the thin portion 31 remains on the jig 6 and is separated from the main body of the magnetic element 14.

  FIG. 7 is a cross-sectional view for explaining the operation of the present invention. Part of the shear stress 8 generated by the force applied from the top surface to the bottom surface direction (hereinafter also referred to as the vertical direction) of the magnetic element 14 supported only by the thin part on the jig 6 is along the outer periphery of the magnetic element 14 and The thin portion 31 is destroyed on the plane 9 including the surface in the vertical direction. Further, a tensile stress 10 is generated due to the weight of the magnetic element 14. The thin portion 31 is removed by the tensile stress 10 in such a manner that the thin portion 31 is divided in the vertical direction with a plane 11 including a plane parallel to the upper surface of the magnetic element 14 as a boundary.

  By synthesizing the shear stress 8 and the tensile stress 10, the thin portion 31 breaks along the crack 12 with the vicinity of the boundary between the thin portion 31 and the magnetic element 14 body as a starting point of breakage. The thin portion 31 is removed from the outer peripheral portion.

  The distance between the liquid surface of the cast magnetic slurry 1 and the flat portion 5 of the mold 2 should be adjusted according to the outer diameter of the magnetic element 14 body and the length in the vertical direction, but the outer diameter is 50 mm or more and 100 mm or less. In the case of a substantially cylindrical magnetic element having a vertical length (the height of the magnetic element) of 30 mm or more and 80 mm or less, approximately 0.1 to 3 mm is desirable. If the thickness is 0.1 mm or less, the thin portion 31 in the direction parallel to the upper surface of the magnetic element is easily damaged and remains sharply and indefinitely in the portion protruding from the magnetic element body. On the other hand, if the thickness is 3 mm or more, the amount of waste increases and the yield of the material decreases, and the load applied to the magnetic element body to damage the thin-walled portion increases.

  FIG. 4 is a sectional view showing another magnetic element according to the present invention, and shows a state after casting. FIG. 5 is a sectional view showing another magnetic element according to the present invention, and shows a state where the magnetic element shown in FIG. 4 is removed from the mold.

  The winding 7 is previously arranged on the mold 2 having the flat portion 5 on the inner peripheral portion, and the magnetic slurry 1 is poured to such an extent that the flat portion 5 is hidden. Subsequently, the lid 4 formed with the protrusion 13 on the portion in contact with the liquid surface of the magnetic slurry 1 after casting is placed, heated and cured so as to contact the liquid surface of the magnetic slurry 1, and then the magnetic element 14. Get. A groove 131 is formed between the thin portion 31 and the flat portion 5 of the magnetic element 14 by the protrusion 13 of the lid 4.

  FIG. 6A is a cross-sectional view of another magnetic element according to the present invention, and shows a state where the magnetic element is carried by a jig for removing a thin portion. FIG. 6B is a cross-sectional view of another magnetic element according to the present invention, and shows a state where a thin portion is removed.

  The magnetic element 14 is carried only by the thin portion 31 and is arranged on the jig 6 so that the bottom surface of the magnetic element 14 does not contact the surface on which the jig 6 is placed. Subsequently, a force is applied from the upper surface to the bottom surface of the magnetic element 14 to push down the main body of the magnetic element 14. At this time, shear stress and tensile stress are generated between the main body of the magnetic element 14 and the thin portion 31, and the thin portion 31 remains on the jig 6 and is separated from the main body of the magnetic element 14.

  By forming the groove portion in advance, the force applied to the magnetic element 14 can be reduced, and the thin portion 31 can be removed more reliably because the shear stress for breaking the thin portion 31 also acts effectively. Become.

  FIG. 8 is a sectional view for explaining the operation of the present invention. When a force is applied from the top surface to the bottom surface of the magnetic element 14 supported by the thin portion 31 only on the jig 6, a shear stress is efficiently applied toward the groove portion 131, and the crack 12 is generated. The groove 131 is preferably formed slightly inside the outer peripheral portion of the magnetic element 14 body, which is the starting point of destruction, because the reproducibility of the position and shape of the crack 12 is preferable. That is, it is preferable to configure the lid 4 so that the protrusions 13 are arranged corresponding to the inner peripheral side of the flat part 5 of the mold 2.

  FIG. 4 shows an example in which the bottom surface of the lid 4 and the protrusion 13 are in contact with the magnetic slurry 1, but the same effect can be obtained even when only the protrusion 13 enters the magnetic slurry 1. The thickness and size of the thin wall portion 31 and the groove portion 131 are determined by the arrangement of the lid 4, and the positional relationship between them can be adjusted by changing the shape of the lid 4 and locking it to the mold 2, for example.

  By forming the groove portion in this manner, the broken portion can be formed thin even if the thin portion is thick, regardless of the example in the 0026 paragraph, so that the thin portion can be stably removed even under a low load. Can be done.

  The jig 6 carries the magnetic element 14 only by the thin part 31, and the shape in which the bottom surface of the magnetic element 14 does not contact the surface on which the jig is placed, that is, the magnetic element 14 excluding the thin part 31 is described above. Any shape that fits or loosely fits in a state of floating from the mounting surface may be used, for example, a bowl-shaped, cylindrical, U-shaped continuous body or a plurality of block bodies having the above-mentioned effects Etc. are preferable.

  It is more preferable that the jig 6 has a shape that can be supported over the entire circumference of the upper surface of the thin portion 31 and that the thin portion 31 can be destroyed and removed simultaneously. This is because if a part of the thin portion 31 remains sharp and irregularly shaped, it becomes difficult to remove it to a shape that can withstand use.

  In the above description, the jig 6 has a length in the vertical direction longer than the length of the magnetic element 14 in the vertical direction. However, if the surface on which the jig 6 is placed is movable, the jig 6 can be moved. The vertical relationship between the magnetic element 14 and the vertical length of the magnetic element 14 can be arbitrarily set.

  The material of the jig 6 may be any member as long as it has the above-described shape and has sufficient strength, hardness and workability to carry the magnetic element 14, for example, carbon steel, alloy steel, stainless steel. Steel or the like is preferred.

  As the magnetic slurry 1, for example, a general material in which a metal magnetic powder and a thermosetting liquid resin are mixed to form a slurry can be used. The thermosetting resin preferably has a low viscosity so that fluidity is sufficient when it is made into a slurry. For example, an epoxy resin is preferably used. As the magnetic powder, for example, general powders such as dust powder such as gas atomized powder of Fe-Si 6.5% material can be used. When mixing these with a resin to form a slurry, alumina powder, silica powder, or the like may be blended at the same time, and the permeability of the dust powder, which is a magnetic material, may be reduced to adjust the magnetic permeability.

  The magnetic element 14 and the mold 2 have been described assuming a cylindrical shape, but are not limited to this, and may be a prismatic shape. In the case of a prismatic shape, the aforementioned inner diameter and outer diameter indicate the maximum diameter.

  The present invention can be applied to any generally used size of the magnetic element 14, but the thickness and shape of the thin portion 31 depend on the size and shape of the magnetic element 14. It is good to adjust appropriately.

  Since the portion of the magnetic element 14 from which the thin portion 31 has been removed is not a grinding surface but a fracture surface, even individual magnetic particles are not destroyed. Therefore, the surface of the magnetic element manufactured by grinding the surface of the hardened resin contained in the magnetic slurry and the magnetic particle surface having no grinding marks, leaving the grinding marks to the magnetic particles themselves. It has a different surface morphology.

DESCRIPTION OF SYMBOLS 1 Magnetic slurry 2 Type | mold 21 Tapered part 3 Deposit 31 Thin part 4 Cover 41 Tapered part 5 Flat part 6 Jig 7 Winding 8 Shear stress 9 Plane including a surface in a vertical direction 10 Tensile stress 11 Including a surface parallel to the upper surface Plane 12 Crack 13 Projection 131 Groove 14 Magnetic element

Claims (9)

  A magnetic element obtained by pouring a magnetic slurry obtained by kneading soft magnetic powder and a resin into a mold in which a winding is previously arranged and curing, and then taking out the cured magnetic slurry containing the winding from the mold. The inner diameter at a position farther from the bottom surface of the mold than the reference surface when the position closer to the bottom surface of the mold than the liquid surface where the magnetic slurry is to be cast is used as the mold. A bottomed columnar body having a flat portion parallel to the bottom surface of the mold on the inner peripheral surface, which is configured to be larger than an inner diameter at a position closer to the bottom surface of the mold than the reference surface including the reference surface. The manufacturing method of the magnetic element characterized by using this.   The magnetic member according to claim 1, wherein after casting the magnetic slurry, a lid member is used which forms a thin portion between the flat portion and the inner peripheral surface in contact with the liquid surface of the magnetic slurry. Device manufacturing method.   After curing the magnetic slurry, the jig is used to destroy and separate at least a part of the thin portion from the magnetic element molded body obtained by removing the lid member and the mold. A method of manufacturing a magnetic element according to claim 1.   4. The magnetic element molded body and the thin portion are separated by supporting the thin portion and applying a force in a direction from the upper surface to the bottom surface of the magnetic element molded body. The manufacturing method of the magnetic element in any one.   The magnetic element molding is carried out by supporting only the thin-walled portion, separating the bottom surface of the magnetic element molded body from the mounting surface of the jig, and applying a force in a direction from the top surface to the bottom surface of the magnetic element molded body. The method of manufacturing a magnetic element according to claim 1, wherein a body and the thin portion are separated.   6. The method of manufacturing a magnetic element according to claim 1, wherein the lid member has a protrusion at a portion in contact with the liquid surface of the magnetic slurry.   The method of manufacturing a magnetic element according to claim 1, wherein the protrusion is provided in a portion corresponding to an inner periphery of the flat portion.   A magnetic element obtained by pouring a magnetic slurry obtained by kneading soft magnetic powder and a resin into a mold in which a winding is previously arranged and curing, and then taking out the cured magnetic slurry containing the winding from the mold. When the position closer to the bottom surface of the mold than the liquid surface to which the magnetic slurry is to be cast is used as the reference surface, the inner diameter at a position farther from the bottom surface of the mold than the reference surface is Using a bottomed columnar body that includes a reference surface and is configured to be larger than an inner diameter at a position closer to the bottom surface of the mold than the reference surface, and having a flat portion parallel to the bottom surface of the mold on the inner peripheral surface, After casting the magnetic slurry, using a lid member that is in contact with the liquid surface of the magnetic slurry to form a thin portion between the flat portion and the inner peripheral surface, and after curing the magnetic slurry, Obtained by removing the lid member and the mold From sexual element green body, by using a jig, the magnetic element characterized by comprising separated by destroying at least a portion of the thin portion.   9. The magnetic element according to claim 8, wherein the surface formed by separating the thin portion is composed of a fracture surface of the cured resin and the soft magnetic powder surface without grinding marks.

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