JP2013030756A - Green compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a green compact having low loss and high productivity, a core for a reactor having the green compact, and a magnetic circuit component.SOLUTION: A green compact 10 is formed by compression-molding coated soft magnetic material powders having insulation coats, and is a deformed frustum mainly consisting of a frustum part 113 sandwiched between plate-like parts 111, 112 disposed so as to face each other. A longitudinal section of the green compact 10 consists of a trapezoidal surface 113s, a rectangular-shaped surface 111s at long side connected to a long side of the trapezoidal surface 113s, a rectangular-shaped surface 112s at short side connected to a short side of the trapezoidal surface 113s. A sliding surface of a molding die mainly consists of an outer peripheral surface 113o of the frustum part 113. Friction between a compression molded product and the molding die is reduced and damage of insulation coats of the green compact 10 can be reduced because the outer peripheral surface 113o is inclined to the extraction direction of the compression molded product. Therefore the green compact 10 has low loss, and high productivity by shortening post-processing time.

Description

  The present invention relates to a green compact used for a magnetic core material provided in a magnetic circuit component such as a reactor, a core for a reactor, and a magnetic circuit component including the green compact. In particular, the present invention relates to a green compact with low loss and excellent productivity.

  Magnetic circuit components including a magnetic core made of a soft magnetic material such as iron or an alloy thereof and a coil disposed on the magnetic core are used in various fields. As a material for the magnetic core, there is a green compact. The green compact is typically a raw material powder made of a soft magnetic material in a molding space formed by a die having a through hole and a lower punch arranged to close one opening of the through hole of the die. After filling, the raw material powder is compression-molded with an upper punch and a lower punch. The compression molded product extracted from the die is usually subjected to heat treatment for the purpose of removing distortion.

  When the magnetic circuit component is used in an alternating magnetic field, iron loss (generally the sum of hysteresis loss and eddy current loss) occurs in the magnetic core. In particular, when used at a high frequency such as several kHz or more, eddy current loss becomes remarkable, and therefore it is desired for the magnetic core to reduce eddy current loss. In order to reduce eddy current loss, it has been proposed to increase the electric resistance by using a coating powder having an insulating coating on the outer periphery of a metal particle made of a soft magnetic material such as iron particles as a raw material powder (Patent Document). 1). In addition, the insulating coating is damaged due to sliding contact between the compression molded product and the inner peripheral surface of the die, and the portions exposed to the conductive coating and deformed metal particles come into contact with each other (hereinafter referred to as the bridge portion). In order to remove (refer to), the compression molded product is subjected to post-treatment such as acid treatment (see Patent Document 1).

JP 2006-229203 A

  Development of a green compact with low loss and excellent productivity is desired.

  In recent years, the operating frequency of magnetic circuit components has been increasing, so that a magnetic core with particularly low eddy current loss is desired. Reduction of eddy current loss can be achieved by using the coating powder as described above for the raw material of the green compact and subjecting it to a post-treatment such as an acid treatment to restore the characteristics. However, if the friction between the compression molded product and the inner peripheral surface of the die is large, when the compression molded product is extracted from the die, the insulation is not only applied to the surface of the compression molded product that is in sliding contact with the inner peripheral surface of the die. The coating may be damaged and a bridge portion may be generated. In order to remove the bridge portion existing inside the compression molded product, it is necessary to sufficiently perform the post-treatment. As a result, the processing time becomes longer, and the productivity of the green compact is reduced. Moreover, when there are many bridge | bridging parts, it may be unable to remove completely by the said post-processing, and there exists a possibility that a low-loss compacting body cannot be obtained.

  Then, one of the objectives of this invention is providing the compacting body which is low loss and excellent in productivity. Another object of the present invention is to provide a reactor core and a magnetic circuit component having low loss and excellent productivity.

  If the generation of the bridge portion described above is suppressed, it is possible to shorten the post-processing time performed for the recovery of characteristics, reduce the removal amount, and reliably remove. For reducing the bridge portion, it is effective to reduce, preferably prevent, damage to the insulating coating. As a result of various studies, the present inventors have obtained a compacted green compact with a low loss even if the post-treatment time applied to the compacted molded product extracted from the die is short when the compacted compact is shaped into a specific shape. , And got the knowledge. The reason for this is considered to be that the insulating coating is less likely to be damaged when the compression molded product is extracted from the die. Then, this invention proposes the compacting body of a specific shape.

  The green compact of the present invention is formed by compression-molding coated soft magnetic particles having an insulating coating, and as a cross-section of at least a part of the green compact, a long side and a short side arranged opposite to each other. And a long side rectangular surface connected to the long side of the trapezoidal surface, and a short side rectangular surface connected to the short side of the trapezoidal surface. In the green compact of the present invention, the area of the trapezoidal surface is larger than the total area of the long side rectangular surface and the short side rectangular surface.

  The green compact of the present invention is not a solid having a uniform cross-sectional area when taking a cross section parallel to an arbitrary plane constituting the outer surface, such as a rectangular parallelepiped or a cylinder, but a solid having portions having different cross-sectional areas. is there. Specifically, the green compact of the present invention is a portion in which the trapezoidal surface having a trapezoidal cross section as described above occupies a large proportion, typically a frustum composed of the trapezoidal surface. It has a part mainly composed of a solid. The solid is an inclined surface whose outer peripheral surface mainly intersects with the direction of extraction from the die (the surface constituting the oblique side of the trapezoidal surface), and is in the direction of extraction from the die, such as a rectangular parallelepiped or a cylinder. Friction with the inner peripheral surface of the die can be reduced as compared with a solid body having parallel outer peripheral surfaces. Therefore, in the compression molded product extracted from the die, at least the frustum body portion has a small damaged area of the insulating coating, and can be, for example, only the very surface of the compression molded product, and can also generate a bridge portion. Can be reduced. From this, the green compact of the present invention can omit the post-treatment for removing the bridge portion and can shorten the processing time. Moreover, since the removal amount of a bridge | bridging part can also be reduced because the production | generation of a bridge | bridging part is reduced, this invention compacting body can also suppress the fall of a yield. As mentioned above, this invention compacting body is excellent in productivity. Moreover, since the bridge portion can be sufficiently removed even when the post-treatment time is short, a low-loss magnetic core and reactor can be obtained by using the green compact of the present invention. Therefore, this invention compacting body can contribute to realization of a low-loss magnetic core and a reactor.

  And this invention compacting body provides the long side rectangular surface and the short side rectangular surface so that the said trapezoid surface may be pinched | interposed. A solid whose cross-section is a rectangular surface, typically a columnar body having the same area of a pair of opposed surfaces such as a rectangular parallelepiped or a cylinder, as a place arranged perpendicular to the pressing direction at the time of compression molding, Typically, by adopting a pressure receiving portion at the time of compression molding, the green compact of the present invention is stable with high dimensional accuracy even if it has a portion mainly composed of a frustum body as described above. Can be molded. Also from this point, the green compact of the present invention is excellent in productivity.

  In addition, the powder compact of the present invention can reduce the wear of the mold by reducing the friction between the compression molded product and the mold for molding, and can extend the life of the mold.

  A representative form of the green compact of the present invention is that the boundary surface between the trapezoidal surface and the long-side rectangular surface is the first surface, and the boundary surface between the trapezoidal surface and the short-side rectangular surface Is a surface parallel to the first surface (a surface constituting a side parallel to the long side of the trapezoidal surface in the long side rectangular surface), a surface parallel to the second surface (short In the side-side rectangular surface, any surface that forms a side parallel to the short side of the trapezoidal surface constitutes the outer surface, and a form mainly composed of the above-described frustum body is exemplified. In addition, the form which has the part connected to the said long side rectangular surface is mentioned. In this form, the surface parallel to the second surface is the outer surface, the boundary surface between the long-side rectangular surface and the connected portion is a virtual surface parallel to the first surface, and a part of the connected portion is The surface is the outer surface, and the above-described frustum body is the main form.

  As one form of the green compact of the present invention, the boundary surface between the trapezoidal surface and the long side rectangular surface is the first surface, and the boundary surface between the trapezoidal surface and the short side rectangular surface is the first surface. When it is set as two surfaces, the form shape | molded so that the direction perpendicular | vertical to at least one surface of a 1st surface and a 2nd surface may turn into a pressurization direction is mentioned.

  In the above form, the first surface and the second surface constituting the above-mentioned frustum body are arranged orthogonal to the pressurizing direction at the time of molding, and the outer peripheral surface constituting the frustum body (configures the hypotenuse of the trapezoidal surface) The surface to be formed becomes, for example, a portion formed by the inner peripheral surface of the die. Therefore, the said form can reduce the friction with the internal peripheral surface of die | dye as mentioned above, can reduce the damage of an insulating film, and can manufacture a low-loss compacting body with high productivity.

  As one form of this invention compacting body, the form in which both the surface parallel to said 1st surface and the surface parallel to said 2nd surface are pressure-molding surfaces is mentioned.

  The pressure molding surface is mainly a surface molded by the upper punch or the lower punch, and constitutes the outer surface of the powder compact. Therefore, the above-described form includes a surface parallel to the first surface and the second surface. It can be said that both surfaces parallel to the surface constitute the outer surface of the green compact. In addition, since the trapezoidal surface exists so as to be sandwiched between both rectangular surfaces of the long-side rectangular surface and the short-side rectangular surface, the above-described form is a portion in which the cross section is configured by a trapezoidal surface ( It can be said that the frustum body part) is sandwiched between the pressure molding surfaces. Then, the above form reduces the damage to the insulating coating as described above, because the outer peripheral surface of the portion (frustum body portion) composed of the trapezoidal surface becomes a portion formed by the inner peripheral surface of the die. Thus, a low-loss compact can be produced with high productivity.

  As one form of this invention compacting body, the form utilized for the location in which the part which has the said trapezoid-shaped surface is arrange | positioned with a cylindrical coil is mentioned. In this embodiment, it is preferable that the surface constituting the hypotenuse of the trapezoidal surface is disposed so as to face the inner peripheral surface of the coil.

  A typical example of the surface constituting the hypotenuse of the trapezoidal surface is the outer peripheral surface of the frustum body. On this surface, damage to the insulating coating is reduced as described above, and a healthy insulating coating exists, and the soft magnetic particles are insulated from each other by this insulating coating. Alternatively, when the above-described post-treatment is performed on this surface, the bridge portion is removed and the soft magnetic particles are insulated from each other by the insulating coating. Therefore, this surface has high electrical resistance (surface resistance). The said form can reduce an eddy current loss effectively by arrange | positioning such a surface excellent in electrical insulation so that the inner peripheral surface of a coil may be opposed.

  As one form of the green compact of the present invention, the boundary surface between the trapezoidal surface and the long side rectangular surface is the first surface, and the boundary surface between the trapezoidal surface and the short side rectangular surface is the first surface. When two surfaces are used, a form in which the ratio of the area of the second surface to the area of the first surface is 80% or more and 99.8% or less can be given. Further, as one form of the green compact of the present invention, there is a form in which the taper angle formed by the oblique side of the trapezoidal surface and the extended line of the short side of the long side rectangular surface is 0.1 ° or more and 6 ° or less. Can be mentioned.

  The said form can reduce damage of an insulating film, ensuring sufficient magnetic path area because the ratio of the area of said 1st surface and said 2nd surface and a taper angle satisfy | fill the said specific range. Therefore, in particular, the above-described form has inferior magnetic characteristics and a low level compared to the case where the portion where the cylindrical coil is disposed is a solid having a uniform cross-sectional area such as a rectangular parallelepiped or a cylindrical shape. Loss and excellent productivity. Both the area ratio and the taper angle can satisfy the specific range. In the long side rectangular surface, the side parallel to the long side of the trapezoidal surface is the same length as the long side, and in the short side rectangular surface, the side parallel to the short side of the trapezoidal surface is the short side. When the length is the same, the area of the first surface and the area of the surface parallel to the first surface are substantially the same, and the area of the second surface and the area of the surface parallel to the second surface are substantially the same. Is the same. Therefore, when the surface parallel to the first surface and the surface parallel to the second surface constitute the outer surface of the green compact, the area of the first surface is the area of the surface parallel to the first surface, the second As the surface area, the surface area parallel to the second surface can be used. Alternatively, the area of the first surface is a cross-sectional area cut at the boundary between the trapezoidal surface and the long side rectangular surface, and the area of the second surface is the boundary between the trapezoidal surface and the short side rectangular surface. In addition to the cross-sectional area cut at, the projected area projected in the axial direction of the frustum body can be used.

  The green compact of the present invention can be suitably used as a material for a magnetic core of a reactor. Then, the form which provides this invention compacting body as a core for this invention reactor is proposed. Or the form which provides this invention compacting body as this invention magnetic circuit components is proposed. The magnetic circuit component of the present invention includes a magnetic core and a cylindrical coil disposed on a part of the magnetic core. The magnetic core includes an inner core portion disposed in the coil and an exposed core portion that is exposed from the coil and forms a closed magnetic path together with the inner core portion. And the said inner core part comprises the above-mentioned this invention compacting body. A typical example of the magnetic circuit component of the present invention is a reactor.

  Since the present invention green compact provides a low-loss magnetic core as described above, the present reactor core comprising the present powder compact, the present powder compact or the present reactor core. The magnetic circuit component according to the present invention has a low loss. Moreover, since this invention compacting body is excellent in productivity as mentioned above, this invention core for reactors and this invention magnetic circuit components which use this invention compacting body as a raw material are also excellent in productivity.

  The green compact of the present invention having the above specific shape can be produced, for example, by subjecting a compression-molded product formed into an appropriate shape to a process such as cutting. However, the cutting process destroys the insulating coating. Therefore, the following manufacturing method using a molding die having a specific shape can be suitably used for manufacturing the green compact of the present invention. In this manufacturing method, after filling a molding space formed by a through hole provided in a die and a first punch inserted into the through hole with a coated soft magnetic powder having an insulating film, the first punch and the through hole are filled. The present invention relates to a method for producing a green compact by compression molding the powder with a second punch inserted into the hole. When the die has a cross section taken along the axial direction of the through hole, the die is sandwiched between the straight portions provided on the openings of the through holes and the straight portions, and the second punch is inserted. A taper portion that tapers from the side toward the side where the first punch is inserted. And the said shaping | molding space is formed so that the said taper part may be included.

  The manufacturing method uses a die having a specific shape including the tapered portion, and uses the tapered portion as a part of the molding space, and forms a part of the outer peripheral surface of the compression molded product by the tapered portion. That is, the said manufacturing method can shape | mold the compression molding product in which a part of outer peripheral surface has a part comprised from an inclined surface by a taper part. Such a compression-molded product can reduce the friction with the inner peripheral surface of the die as described above at the time of extraction from the die, and therefore can effectively reduce the damage to the insulating coating. Moreover, since the obtained compression molding has a part with little damage of an insulating film, post-processing, such as removal of a bridge | bridging part, can be abbreviate | omitted or processing time can be shortened. Therefore, the above production method can produce a low-loss compacted product (typically, the compacted product of the present invention) with high productivity.

  The compact body of the present invention, the core for reactor of the present invention, and the magnetic circuit component have low loss and excellent productivity.

(A) is a schematic perspective view of the green compact of Embodiment 1, (B) is a (B)-(B) cross-sectional view of (A), (C) is this powder compact in the coil It is sectional drawing explaining the state which has arrange | positioned. FIG. 3 is a process explanatory diagram illustrating an example of a manufacturing procedure of the green compact of the first embodiment. 5 is a schematic perspective view of a reactor according to Embodiment 2. FIG. 5 is an exploded perspective view of a magnetic core provided in the reactor of Embodiment 2. FIG. It is explanatory drawing explaining an example of the metal mold | die used for manufacture of a cyclic | annular compacting body. (A) is a front view of a green compact used for an ER type core, and (B) is a rear view of this green compact. It is explanatory drawing explaining an example of the metal mold | die used for manufacture of the compacting body utilized for an ER type | mold core. (A) is a front view of a green compact used for a T-shaped core, and (B) is a rear view of this green compact. (A) and (B) are explanatory views for explaining an example of a molding die used for manufacturing a green compact used for a T-shaped core.

  Embodiments of the present invention will be described below. First, the green compact of the present invention will be described with reference to FIGS. In the drawings, the same reference numerals indicate the same names.

Embodiment 1
The green compact 10 is a magnetic material that is formed by compressing magnetic powder with a molding die (typically, a die, an upper punch, and a lower punch) and is used as a magnetic core material. . The compact 10 is a solid similar to a rectangular parallelepiped, but has a non-uniform cross-sectional area when taking a cross-section parallel to an arbitrary outer surface, such as a rectangular parallelepiped, and has a different cross-sectional area. The point that is a solid is the greatest feature. This will be described in more detail below.

(Green compact)
The green compact 10 is a deformed frustum body that includes plate-like parts 111 and 112 arranged opposite to each other and a weight base part 113 sandwiched between the plate-like parts 111 and 112, and the weight base part 113 as a main component. When the green compact 10 is cut along a plane along the direction from one plate-like portion 111 to the other plate-like portion 112 (a plane parallel to the thickness direction of the plate-like portions 111, 112), the cross section (hereinafter referred to as the cross section) (This cross section is referred to as a longitudinal cross section), as shown in FIG.1 (B), two rectangular surfaces 111s and 112s arranged opposite to each other, and a trapezoidal surface 113s sandwiched between the rectangular surfaces 111s and 112s. Consists of. Both rectangular surfaces 111s and 112s and the trapezoidal surface 113s are smoothly connected, and each rectangular surface 111s and 112s is a long side rectangular surface 111s and a trapezoidal surface 113s connected to the long side of the trapezoidal surface 113s. The short side rectangular surface 112s connected to the short side. The length of the two opposing sides in the long side rectangular surface 111s is equal to the length of the long side of the trapezoidal surface 113s. The length of the two opposing sides in the short side rectangular surface 112s is equal to the length of the short side of the trapezoidal surface 113s. Further, the long side of the short side rectangular surface 112s (= the short side of the trapezoidal surface 113s) is shorter than the long side of the long side rectangular surface 111s. Therefore, the trapezoidal surface 113s tapers from the long side rectangular surface 111s toward the short side rectangular surface 112s.

  In the figure, the boundary between the plate-like portion and the frustum portion and the inclination of the frustum portion are emphasized for easy understanding, but the plate-like portion is sufficiently small compared to the frustum portion, and When the taper angle to be described later is small, the green compact looks substantially a rectangular parallelepiped. In addition, in FIGS. 1 (B), 1 (C), 2 (B), and FIGS. 5 to 9 to be described later, the boundary between the plate-like portion and the frustum portion and the straight portion and the tapered portion are easily understood. Although the boundary is indicated by a one-dot chain line, it is a virtual line.

  The green compact 10 is mainly composed of a frustum portion 113. “Mainly” or “mainly” to be described later means that when the longitudinal section is taken, the area S3 of the trapezoidal surface 113s constituting the frustum 113 is the long side rectangular surface 111s constituting the plate-like portions 111 and 112. The total area of the area S1 and the area S2 of the short-side rectangular surface 112s is larger than S1 + S2 (S3> S1 + S2). As described later, the plate-like portions 111 and 112 preferably have a smaller thickness (size in the vertical direction (cutting direction of the longitudinal section) in FIG. 1B), so that the area S3 of the trapezoidal surface 113s is a total. More preferably, the area is sufficiently larger than S1 + S2 (S3 >> S1 + S2). Specifically, the area S3 of the trapezoidal surface 113s preferably occupies more than 50% and more than 70% of the total area: S1 + S2 + S3.

  The frustum portion 113 is a frustum body corresponding to the planar shape of the plate-like portions 111 and 112, and the outer peripheral surface 113o (the surface constituting the hypotenuse of the trapezoidal surface 113s in the longitudinal section) is a flat surface (the trapezoidal shape in the longitudinal section) The hypotenuse of the surface 113s may be a straight line) or a curved surface (the same curve) (a plane in FIG. 1A). When the frustum portion 113 is cut along a plane parallel to the plate-like surfaces of the plate-like portions 111 and 112 (pressure forming surfaces 111f and 112f described later), the area of the cross section (hereinafter, this cross-section is referred to as a transverse cross-section). However, it depends on the cutting position. The cross-sectional area when cut along a plane near one plate-like part 111 is larger than the cross-sectional area when cut along a plane near the other plate-like part 112.

  The outer peripheral surface 113o of the frustum 113 is formed by the inner peripheral surface of the die of the molding die. Therefore, when the inclination angle of the frustum part 113, specifically, when taking a longitudinal section, the hypotenuse (the approximate line or tangent or chord in the case of a curve) of the trapezoidal surface 113s and the long side rectangular surface If the angle formed by the extension of the short side of 111s (hereinafter referred to as the taper angle θ) is 0.1 ° or more, the friction with the inner peripheral surface of the die can be reduced, and the damage to the insulating coating can be effectively reduced. . The greater the taper angle θ, the easier it is to prevent damage to the insulating film, but if it is too large, the area of the boundary surface between the frustum 113 and the other plate-like part 112 (the length of the short side of the trapezoidal surface 113s) will be increased. It becomes smaller (shorter), the magnetic path area is reduced, and the magnetic properties are lowered. Accordingly, the taper angle θ is preferably 6 ° or less. Although it depends on the thickness of the frustum 113 (the height of the trapezoidal surface 113s), the taper angle θ is preferably 0.1 ° to 3 °, and more preferably 0.1 ° to 2 °.

  When the taper angle 113 has a uniform taper angle θ over the entire circumference of the outer peripheral surface 113o, it is possible to effectively reduce the friction between the compression molded product and the inner peripheral surface of the die. There is an advantage that it is easy to perform a regular pressurization and is excellent in dimensional accuracy, and that the mold can be made in a simple shape. It should be noted that only a part of the outer peripheral surface 113o of the frustum portion 113 can be formed from an inclined surface. For example, when the frustum portion 113 has a truncated pyramid shape, only one of the surfaces constituting the outer peripheral surface can be an inclined surface. In this form, when a certain cross section is taken, the taper angle for each hypotenuse provided on the trapezoidal surface in this cross section is different.

  Examples of the planar shape of the plate-like portions 111 and 112 include a rectangle as shown in FIG. 1A, a circle, an ellipse, a race track shape, and a rounded corner shape obtained by rounding corners of the rectangle to a desired angle. For example, when the green compact 10 is inserted into the cylindrical coil 2 as shown in FIG. 1 (C), the planar shape is formed along the inner peripheral shape of the coil 2. The body 10 can be brought close to the coil 2 and the magnetic component can be miniaturized. When the planar shape of the plate-like portions 111 and 112 is a rectangle, the green compact 10 is a truncated pyramid shape such as a square frustum, and when it is a circle or an ellipse, a frustum shape or an elliptic frustum shape is used. Become. In the green compact 10, the cross-sectional area of the cross section of the plate-like portion 111 and the cross-sectional area of the cross-section of the plate-like portion 112 are uniform. Alternatively, the planar shape of the plate-like portions 111 and 112 may be a perforated shape such as an annular shape. In this case, the green compact is a solid body including an annular frustum body.

  The plate-like portions 111 and 112 are pressure receiving portions that directly receive pressure during compression molding. By providing the plate-like portions 111 and 112 as pressure receiving locations, the green compact 10 can be accurately formed even with the frustum portion 113 as a main component.

  The plate-like portions 111 and 112 have pressure forming surfaces 111f and 112f formed by an upper punch or a lower punch that applies pressure during compression molding. Here, the pressure molding surface 111f is a surface parallel to the boundary surface between the trapezoidal surface 113s and the long side rectangular surface 111s, and is parallel to the long side of the trapezoidal surface 113s in the long side rectangular surface 111s. It is a surface that constitutes a long side. The pressure molding surface 112f is a surface parallel to the boundary surface between the trapezoidal surface 113s and the short-side rectangular surface 112s, and the short-side rectangular surface 112s has a side parallel to the short side of the trapezoidal surface 113s. It is a surface to compose.

  Note that the green compact has a shape (such as how to apply the corner R) and the deformation state of the magnetic particles in the cross section (generally, the particles constituting the green compact are plastically deformed in a direction perpendicular to the pressing direction. The direction of pressurization can be determined by, for example, flattening). Therefore, the outer surface in the direction orthogonal to the pressing direction can be determined as the pressure forming surface. Further, it can be determined that the outer surface sandwiched between the opposing pressure forming surfaces is typically a surface (sliding contact surface) formed by the inner peripheral surface of the die. In addition, the slidable contact surface can be determined based on the presence or absence of a rub mark.

  The thicknesses of the plate-like portions 111 and 112 may be thin as long as the frustum portion 113 can be formed, and it is considered that a thickness of about 0.3 mm to 2 mm is sufficient. Since the outer peripheral surfaces 111o, 112o of the plate-like portions 111, 112 are outer peripheral surfaces parallel to the extraction direction from the die in the compression-molded product, the thinner the plate-like portions 111, 112, the smaller the compression-molded product and the molding die. And the friction of the insulating film can be reduced. Accordingly, the thickness of the plate-like portions 111 and 112 is preferably 2 mm or less (total of 4 mm or less), and further preferably 1 mm or less (total of 2 mm or less).

  Here, the pressure-molded surface 111f constituting the long side of the long side rectangular surface 111s has areas of the weight base part 113 (trapezoidal surface 113s) and the plate part 111 (long side rectangular surface 111s). ), The area of the cross section (transverse section) cut at the boundary between the frustum 113 (trapezoidal surface 113s) and the plate-like part 111 (long-side rectangular surface 111s), Equal to any of the projected areas. The pressure molding surface 112f constituting the long side of the short side rectangular surface 112s has an area of the frustum portion 113 (trapezoidal surface 113s) and the plate portion 112 (short side rectangular surface 112s). The area of the boundary surface, the area of the cross section (transverse section) cut at the boundary between the frustum 113 (trapezoidal surface 113s) and the plate-like part 112 (short side rectangular surface 112s), the projected area of the boundary surface It is equal to both. As described above, since the lengths of the long sides of the rectangular surfaces 111s and 112s are different, the areas of the pressure molding surfaces 111f and 112f are also different. Here, the area of the plate-like portion 111 is larger than that of the plate-like portion 112. The ratio of the area of the plate-like portion 112 having a small area to the plate-like portion 111 having a large area varies depending on the thickness of the frustum portion 113 (the height of the trapezoidal surface 113s) and the taper angle θ described above. For example, when the thickness of the frustum portion 113 is constant, the smaller the taper angle θ, the smaller the taper angle θ, the smaller the thickness of the frustum portion 113 (thinner), the larger the ratio of the above areas. Become. When the plate-like portions 111 and 112 are used for the magnetic path, the ratio of the areas is preferably 80% or more so that a sufficient magnetic path area can be secured. The larger the area ratio, the larger the magnetic path area can be secured. However, since the taper angle θ becomes smaller and the effect of reducing damage to the insulating coating becomes smaller, it is preferably 99.8% or less. The area ratio is preferably 88.4% to 99.8%, more preferably 92% to 99.8%.

(Production method)
{Mold for molding}
The powder compact 10 having the specific shape can be manufactured using, for example, a molding die 100 shown in FIG. First, the molding die 100 will be described.

  The molding die 100 includes a cylindrical die 103 provided with a through-hole 103h and a columnar first inserted through each opening of the through-hole 103h of the die 103 and arranged oppositely in the through-hole 103h. A punch (lower punch 102) and a second punch (upper punch 101) are provided. The molding die 100 has a bottomed cylindrical space formed by inserting the lower punch 102 in the through hole 103h of the die 103 as a molding space, and the raw powder filled in the space is used as the upper punch 101 and the lower punch 102. Press and compress to form a green compact. In the molding die 100, the through hole 103h of the die 103 has a specific shape.

  In the through hole 103h of the die 103, the opening area of one opening is different from the opening area of the other opening, and the intermediate part in the axial direction of the through hole 103h is formed of an inclined surface. Specifically, as shown in FIG. 2 (A), when taking a cross section in the axial direction of the through-hole 103h, the straight portions 1011 and 1012 provided on each opening side of the through-hole 103h, and these straight portions A tapered portion 1013 that is sandwiched between 1011 and 1012 and tapers from a side where the upper punch 101 is inserted (upper side in FIG. 2) toward a side where the lower punch 102 is inserted (lower side in FIG. 2). An outer peripheral surface 111o of one plate-like portion 111 of the green compact 10 shown in FIG. 1 is formed by an inner peripheral surface constituted by one linear portion 1011 of the die 103, and is constituted by the other linear portion 1012. The outer peripheral surface 112o of the other plate-like portion 112 of the green compact 10 is formed by the inner peripheral surface, and the outer peripheral surface 113o of the frustum portion 113 of the green compact 10 is formed by the inclined surface constituted by the tapered portion 1013. Is formed. The pressure forming surfaces 111f and 112f (FIG. 1) of the plate-like portions 111 and 112 are the surfaces facing the lower punch in the upper punch 101 (the pressing surface 101p in FIG. 2), and the surfaces facing the upper punch in the lower punch 102 (FIG. 2). Then, it is formed by the pressing surface 102p).

  The angle of the taper portion 1013 (the size of the angle formed by the straight extension line forming one straight portion 1011 and the hypotenuse forming the taper portion 1013) is substantially equal to the taper angle θ of the green compact 10 (FIG. 1). Therefore, the taper angle θ is preferably selected so as to satisfy the above-mentioned range so that the taper angle θ becomes a desired value. Since the length along the axial direction (vertical direction in FIG. 2) of the through hole 103h in the taper portion 1013 is substantially equal to the thickness of the frustum portion 113 (FIG. 1) of the green compact 10, The thickness of the frustum portion 113 may be appropriately selected so as to have a desired value. The opening area of each opening of the through-hole 103h and the areas of the pressing surfaces 101p, 102p of the upper punch 101 and the lower punch 102 are the areas of the plate-like portions 111, 112 (FIG. 1) (pressure forming surfaces 111f, 112f (FIG. 1 Therefore, the area of the plate-like portions 111 and 112 is preferably selected appropriately so as to satisfy the above-described area ratio.

  As a constituent material of the molding die 100, an appropriate high-strength material (such as high-speed steel) that has been conventionally used for molding a green compact (mainly composed of metal powder) can be used. .

  At least one of the upper punch 101 and the lower punch 102 and the die 103 are relatively movable. In the molding die 100 shown in FIG. 2, the lower punch 102 is fixed to a main body device (not shown) and cannot be moved, and the die 103 and the upper punch 101 are movable in the vertical direction respectively by a moving mechanism (not shown). is there. In addition, a configuration in which the die 103 is fixed and both the punches 101 and 102 can be moved, and a configuration in which both the die 103 and both the punches 101 and 102 are movable can be adopted. In the form of fixing one punch (here, the lower punch 102), the moving mechanism is simple and the moving operation is easy to control.

  When a lubricant is applied to the molding die 100 (particularly, the inner peripheral surface 103i of the die 103), friction between the raw material powder or the compression molded product and the die 100 can be reduced. Lubricant is a metal soap such as lithium stearate, a fatty acid amide such as stearic acid amide, a solid lubricant such as higher fatty acid amide such as ethylenebisstearic acid amide, a solid lubricant dispersed in a liquid medium such as water. Examples thereof include liquids and liquid lubricants. In addition, if the mold is molded in a heated state (warm molding), the moldability can be further improved. Of course, cold forming may be used.

{Molding procedure}
Next, a procedure for manufacturing the green compact 10 (FIG. 1) using the molding die 100 will be described. The lower punch 102 is inserted into the through-hole 103h of the die 103, and the die 103 and the lower punch 102 form a molding space having a predetermined size. The upper punch 101 is allowed to escape upward.

  Raw material powder to be described later: coated soft magnetic powder is fed into the molding space by a powder feeding device (not shown).

  The upper punch 101 is moved downward and inserted into the through-hole 103h of the die 103, and the raw material powder P is pressurized and compressed by both punches 101 and 102 (FIG. 2 (B)).

The molding pressure is 5 ton / cm ² (≈490 MPa) or more and 15 ton / cm ² (≈1470 MPa) or less. By setting it to 5 ton / cm ² or more, the raw material powder P can be sufficiently compressed, and the relative density of the green compact can be increased. By setting it to 15 ton / cm ² or less, the coated soft magnetic particles constituting the raw material powder P It is possible to suppress damage to the insulating coating due to contact between each other. Compacting pressure 6 ton / cm ² or more 10ton / cm ² or less being more preferred.

  After the upper punch 101 contacts the raw material powder P, the die 103 also moves downward together with the upper punch 101. By moving the die 103 together with the upper punch 101, it is easy to make the pressure applied to the raw material powder P in the molding space uniform. The moving speed of the die 103 and the upper punch 101 can be selected as appropriate. Only the upper punch 101 can be moved.

  After performing the predetermined pressurization, in the molding space, as shown in FIG.2 (B), a surface 1111 having a rectangular cross section formed by the upper punch 101 and one linear portion 1011, and the lower punch 102 Compression molded product comprising a surface 1112 having a rectangular cross section formed by the other straight portion 1012 and a trapezoidal surface 1113 formed by a tapered portion 1013 and sandwiched between both rectangular surfaces 1111 and 1112. Is formed. In order to take out the compression molded product, the die 103 is moved downward.

  When the compression molded product is completely exposed from the die 103, the upper punch 101 is moved upward to collect the compression molded product. After the upper punch 101 is moved upward, the die 103 may be moved downward, or the upper punch 101 and the die 103 may be moved simultaneously.

  In the case of continuous molding, as described above, formation of the molding space → filling of the raw material powder into the molding space → pressurization / compression → removal may be repeated.

  The obtained compression-molded product can be used as it is, but it can be subjected to a heat treatment for the purpose of removing distortion caused by compression. By removing distortion, loss such as hysteresis loss can be reduced. The heat treatment conditions include heating temperature: about 300 ° C. to 800 ° C., holding time: 30 minutes to 60 minutes. The higher the heating temperature, the easier it is to remove the strain and the hysteresis loss can be reduced. However, since the insulating coating may be thermally decomposed to increase eddy current loss, it is preferable that the heating temperature is lower than the thermal decomposition temperature. Typically, when the insulating coating is made of an amorphous phosphate such as iron phosphate or zinc phosphate, the heating temperature is preferably up to about 500 ° C., and is excellent in heat resistance such as a metal oxide or silicone resin. In the case of an insulating material, the heating temperature is raised to 550 ° C. or higher, further 600 ° C. or higher, particularly 650 ° C. or higher. The heating temperature and holding time may be appropriately selected according to the constituent material of the insulating coating. The atmosphere during the heat treatment is not particularly limited, but the oxidation of the soft magnetic particles can be prevented if a non-oxidizing atmosphere such as a nitrogen atmosphere or a low oxygen atmosphere with a low oxygen concentration is used.

  The obtained compression molded product or the heat-treated product subjected to the above heat treatment can be subjected to post-treatment such as acid etching for the purpose of removing the portion where the soft magnetic particles are conducted: the bridge portion. In the post-treatment, for example, the treatment time and the concentration of the treatment liquid may be adjusted so that the loss becomes a predetermined magnitude or less.

  From the above, the green compact 10 (FIG. 1) is in the form of either a heat-treated product or a post-processed product that has been subjected to the above-described post-treatment as a compression-molded product.

  When manufacturing an annular compacted body, for example, as shown in FIG. 5, the core rod 104 is coaxially inserted into the cylindrical lower punch 102 and is movable relative to the lower punch 102. It is preferable to use a mold 110 for molding. As described above, the taper portion 1013 is provided on the inner peripheral surface 103i of the through hole 103h of the die 103, and the outer peripheral surface of the core rod 104 also has a taper portion similar to that of the die 103i. For example, in the region of the upper punch 101 side of the core rod 104, the core rod 104 having a tapered portion opposite to the tapered portion 1013 of the die 103, that is, a tapered portion that tapers toward the upper punch 101 side is used. By using the molding die 110, it is possible to reduce the friction between the inner peripheral surface constituting the through-hole provided in the annular powder compact and the outer peripheral surface of the core rod 104, and to reduce damage to the insulating coating. In the obtained annular compacted body, the cross-section cut along the plane passing through the axis of the through-hole has a trapezoidal surface 113s sandwiched between the long-side rectangular surface 111s and the short-side rectangular surface 112s. It is a shape that exists symmetrically as the center.

(Raw material powder)
The magnetic powder used as the raw powder of the green compact 10 (FIG. 1) is a coated soft magnetic powder comprising a soft magnetic particle made of a soft magnetic material and an insulating coating provided on the surface of the soft magnetic particle. .

  The soft magnetic material preferably contains a metal, particularly 50% by mass or more of iron. For example, pure iron (Fe), other Fe-Si alloys, Fe-Al alloys, Fe-N alloys, Fe-Ni alloys, Fe-C alloys, Fe-B alloys, Fe-Co alloys There is one kind of iron alloy selected from alloys, Fe-P alloys, Fe-Ni-Co alloys, and Fe-Al-Si alloys. In particular, a compacted body made of pure iron in which 99% by mass or more is Fe can obtain a magnetic core having a high magnetic permeability and magnetic flux density, and a compacted body made of an iron alloy can easily reduce eddy current loss, A lower loss magnetic core can be obtained.

  The soft magnetic particles preferably have an average particle size of 1 μm or more and 70 μm or less. When the average particle size is 1 μm or more, it is excellent in fluidity and can suppress an increase in hysteresis loss, and when it is 70 μm or less, when the obtained green compact is used as a magnetic core, it is as high as 1 kHz or more. Even when used at a frequency, eddy current loss can be effectively reduced. When the average particle size is 50 μm or more, it is easy to obtain the effect of reducing the hysteresis loss, and it is easy to handle the powder. The average particle diameter refers to a particle diameter of particles in which the sum of masses from particles having a small particle diameter reaches 50% of the total mass in the particle diameter histogram, that is, 50% particle diameter (mass).

  As the insulating film, an appropriate insulating material having excellent insulating properties can be used. For example, the insulating material includes oxidation of one or more metal elements selected from Fe, Al, Ca, Mn, Zn, Mg, V, Cr, Y, Ba, Sr, and rare earth elements (excluding Y). Metal oxides such as oxides, nitrides and carbides, metal nitrides and metal carbides. Alternatively, examples of the insulating material include compounds other than the metal oxide, metal nitride, and metal carbide, for example, one or more compounds selected from phosphorus compounds, silicon compounds, zirconium compounds, and aluminum compounds. Other insulating materials include metal salt compounds, such as metal phosphate compounds (typically iron phosphate, manganese phosphate, zinc phosphate, calcium phosphate, etc.), borate metal salt compounds, silicate metal salt compounds, Examples include titanic acid metal salt compounds. In particular, since the metal phosphate compound is excellent in deformability, the insulation coating made of the metal phosphate compound can easily be deformed following the deformation of the soft magnetic particles during compression molding and is not easily damaged. If the powder which comprises is used, it will be easy to obtain the compacting body in which an insulating film exists in a healthy state. In addition, the insulating coating made of a metal phosphate compound has high adhesion to soft magnetic particles made of an iron-based material and is difficult to drop off from the surface of the particles.

  Examples of insulating materials other than the above include resins such as thermoplastic resins and non-thermoplastic resins and higher fatty acid salts. In particular, a silicon-based organic compound such as a silicone resin is excellent in heat resistance, and thus hardly decomposes when the obtained compression-molded product is subjected to heat treatment.

  For the formation of the insulating film, for example, a chemical conversion treatment such as a phosphate chemical conversion treatment can be used. In addition, for the formation of the insulating film, spraying of a solvent or sol-gel treatment using a precursor can be used. When the insulating coating is formed from a silicone organic compound, wet coating using an organic solvent or direct coating using a mixer can be used.

  The thickness of the insulating coating provided in the soft magnetic particles is 10 nm or more and 1 μm or less. When the thickness is 10 nm or more, insulation between soft magnetic particles can be secured, and when the thickness is 1 μm or less, a decrease in the ratio of the magnetic component in the green compact can be suppressed due to the presence of the insulating coating. That is, when a magnetic core is produced with this compacting body, a significant decrease in magnetic flux density can be suppressed. The thickness of the insulating coating is determined by composition analysis (analyzer using transmission electron microscope and energy dispersive X-ray spectroscopy: TEM-EDX) and inductively coupled plasma mass spectrometer (ICP-MS). In view of the amount of element obtained by the above, the equivalent thickness is derived, and further, the insulation film is directly observed by the TEM photograph to confirm that the order of the equivalent thickness derived earlier is an appropriate value. The average thickness determined by

  A lubricant can be added to the raw material powder. Examples of the lubricant include organic lubricants and inorganic substances such as boron nitride and graphite.

  By using the raw material powder, it is a soft magnetic particle made of the above-described soft magnetic material, and the outer periphery thereof is provided with an insulating coating composed of the above-described insulating material (or one modified by heat treatment) A green compact 10 made of particles is obtained.

(effect)
The green compact 10 is mainly composed of a frustum 113 having a trapezoidal surface 113s in cross section, and the surface (outer peripheral surface 113o) that is in sliding contact with the molding die (the inner peripheral surface of the die) Since it inclines with respect to the extraction direction of a compression molding, the friction at the time of sliding contact can be reduced effectively. Therefore, it is easy to extract the compression molded product from the molding die, and the coated soft magnetic particles constituting the outer peripheral surface of the extracted compression molded product and the vicinity thereof have reduced damage to the insulating coating due to the reduction of the friction. Or where adjacent soft magnetic particles are conducted by plastic deformation: generation of a bridge portion is suppressed. Therefore, when post-processing for removing the bridge portion is performed on the compression molded product, the processing time can be shortened and the amount of removal of the bridge portion can be reduced. For these reasons, the green compact 10 is excellent in productivity.

  In addition, the green compact 10 has a magnetic core material as it is without being subjected to post-treatment, as a result of suppressing the damage to the insulating coating and the generation of the bridge portion, of course, when the above-described post-treatment is performed. It is expected that a low-loss magnetic core can be obtained even when used in the above.

  Furthermore, the compacting body 10 can be expected to extend the life of the mold by reducing the friction with the mold 100 for molding. In addition, since the opening on the upper punch 101 side is wider than the opening on the lower punch 102 side in the through hole 103h of the die 103, air between the coated magnetic particles can be easily released after powder feeding, reducing the degassing time. It is expected to be possible. From these facts, the green compact 10 is excellent in productivity.

Embodiment 2
Next, referring to FIGS. 3 and 4, a reactor will be described as an example of the magnetic circuit component of the present invention. The reactor 1 includes a coil 2 having a pair of cylindrical coil elements 2a and 2b, and a magnetic core 3 that forms a closed magnetic path when the coil 2 is excited. The magnetic core 3 is a pair of columnar inner core portions 31 inserted and arranged in the coil elements 2a and 2b, respectively, and an exposed core portion that is exposed from the coil 2 and connects the pair of inner core portions 31 to form an annular body. With 32. The magnetic core 3 is mainly composed of a plurality of core pieces made of a green compact. A feature of the reactor 1 is that each core piece constituting the inner core portion 31 is formed of the green compact 10 of the first embodiment. A configuration other than the core piece constituting the inner core portion 31 can use a known reactor configuration, and the configurations shown in FIGS. 3 and 4 and the configurations described later are examples.

(coil)
The coil 2 includes a pair of coil elements 2a and 2b formed by spirally winding a single continuous winding 2w having no joint portion, and a connecting portion 2r for connecting both the coil elements 2a and 2b. Each coil element 2a, 2b is a hollow cylindrical body having the same number of turns, arranged in parallel (side by side) so that the respective axial directions are parallel, and wound on the other end side (right side in FIG. 3) of the coil 2 A part of 2w is bent into a U shape to form a connecting part 2r. With this configuration, the winding directions of both coil elements 2a and 2b are the same.

  The winding 2w is preferably a covered wire having an insulating layer made of an insulating material (typically an enamel layer made of polyamideimide) on the outer periphery of a conductor made of a conductive material such as copper, aluminum, or an alloy thereof. Available. As the conductor of the winding 2w, a rectangular wire having a rectangular cross section as well as a round wire having a circular cross section can be suitably used. The coil elements 2a and 2b are edgewise coils formed by edgewise winding a covered rectangular wire having an insulating layer.

(core)
The magnetic core 3 will be described with reference to FIG. The magnetic core 3 includes a pair of columnar inner core portions 31 covered with the coil elements 2a and 2b (FIG. 3), and a pair of exposed core portions 32 that are not disposed with the coil 2 (FIG. 3) and are exposed from the coil 2. And have. Each inner core portion 31 is a columnar body (here, substantially a rectangular parallelepiped) having an outer shape along the inner peripheral shape of each coil element 2a, 2b, and each exposed core portion 32 is a pair of trapezoidal shapes, respectively. A columnar body having a surface. The exposed core portion 32 is disposed so as to sandwich the inner core portion 31 that is spaced apart, and the magnetic core 3 is formed in an annular shape by bringing the end surface of each inner core portion 31 and the inner end surface of the exposed core portion 32 into contact with each other. The

  The inner core portion 31 is a laminate formed by alternately laminating a core piece 31m made of a magnetic material and a gap material 31g made of a material having a lower magnetic permeability than the core piece, typically a non-magnetic material. Is the body. The exposed core portion 32 is also a core piece made of a magnetic material.

  The gap material 31g is a member provided for adjusting the inductance, and specific constituent materials include alumina, glass epoxy resin, unsaturated polyester (all non-magnetic materials), ceramics, phenol resin, etc. Examples thereof include a mixed material in which magnetic powder (for example, ferrite, Fe, Fe-Si, Sendust) is dispersed in a nonmagnetic material.

  For the integration of the core pieces or the integration of the core piece 31m and the gap material 31g, for example, an adhesive or an adhesive tape can be used. An adhesive tape may be used to form the inner core portion 31, and the inner core portion 31 and the exposed core portion 32 may be joined with an adhesive.

  Each core piece 31m of the inner core portion 31 is constituted by the green compact 10 described in the first embodiment. In particular, the core pieces 31m constituting the inner core portion 31 are all formed on the coil elements 2a, 2b (the outer peripheral surface 113o of the weight base portion 113 and the outer peripheral surfaces of the plate-like portions 111, 112 in the green compact 10 (core piece 31m). It is arranged so as to face the inner peripheral surface of FIG. 3) (see FIG. 1C). In other words, each of the core pieces 31m constituting the inner core portion 31 has the pressure-formed surfaces 111f and 112f of the plate-like portions 111 and 112 included in the green compact 10 (core piece 31m) of the coil elements 2a and 2b. The coil elements 2a and 2b are inserted and arranged so as to be orthogonal to the axial direction. Therefore, the outer peripheral surface 113o of the frustum portion 113 is arranged so as to intersect the direction of the magnetic flux generated by the coil elements 2a and 2b by a taper angle θ when the coil 2 is excited. In addition, when the inner core portion 31 is disposed as described above, a section (frustum portion 113) having a different cross-sectional area is obtained by cutting along a plane perpendicular to the direction of the magnetic flux. When the ratio of the taper angle θ and the area is in the specific range described above, in particular, the taper angle θ is sufficiently small and the ratio of the area is sufficiently large, so that the outer peripheral surface 113o of the frustum portion 113 is in the direction of the magnetic flux. They are arranged substantially in parallel. The gap material 31g is disposed in contact with the plate-like portions 111 and 112 of the green compact 10 (core piece 31m).

(Other components)
In addition, in order to improve the insulation between the coil 2 and the magnetic core 3, an insulator made of an insulating resin is provided, or the outer periphery of the combination of the coil 2 and the magnetic core 3 is covered with an insulating resin. The combination can be stored in a case made of a metal material or the like, or the combination stored in the case can be covered with a sealing resin.

(effect)
Reactor 1 is a reactor in which the core 3 is used for the material of the portion (inner core portion 31) housed in the coil 2, and the material is excellent in productivity. 1 itself has excellent productivity. Further, as shown in a test example to be described later, the reactor 1 has a low loss pressure in the magnetic core 3, particularly in a material housed in the coil 2 (inner core portion 31), that is, in a material where eddy current loss is likely to occur. By using the powder molded body 10, the loss is low.

[Modification]
In the second embodiment, a reactor including a pair of coil elements has been described. In addition, one cylindrical coil is provided, and as a magnetic core, a columnar inner core part in which the cylindrical coil is arranged, an outer core part arranged on the outer periphery of the cylindrical coil, and an end face of the cylindrical coil And an end face core portion that connects the inner core portion and the outer peripheral core portion. In this embodiment, the outer peripheral core portion and the end face core portion are exposed core portions. Typically, there are forms called an EI form, an EE form, a pot form, etc. configured by combining an ER type core, an E type core, and an I type core.

  This modification is a configuration in which a magnetic core is combined with a plurality of core pieces, like the reactor 1 of the second embodiment, and at least the powder compact 10 of the first embodiment is used for the core pieces constituting the inner core portion. Is mentioned. In this embodiment, a reactor having a low-loss magnetic core can be manufactured with high productivity by using the green compact 10 of Embodiment 1 as a material for the inner core portion.

  Alternatively, the magnetic core may have a form including an integrally formed ER type core or E type core, or a form including an integrally formed T type core and a] -shaped core. For example, as shown in FIG. 6 (A), the ER type core has a central leg portion arranged in a cylindrical coil among the three leg portions, similar to the green compact 10 of the first embodiment. In addition, when a cross section in the axial direction of the coil is taken, the green compact 11 having the frustum portion 113 whose cross section becomes a trapezoidal surface can be used. The green compact 11 is connected to the frustum portion 113, the shape portion connected to the long side of the frustum portion 113, and the short side of the frustum portion 113, and the cross section is a rectangular surface. And a plate-like portion 112. ] A part of the piece has a portion in which the cross section is rectangular, and this portion can be regarded as a plate-like portion 111 (however, the plate-like portion 111 has three legs in the cross-section. When cutting along the extension line of the long side of the trapezoidal surface and removing the two on both sides, the area S1 of the long side rectangular surface constituting the plate-like part 111 + the short side rectangular shape constituting the plate-like part 112 The area S2 of the surface <the area S3 of the trapezoidal surface constituting the frustum 113 is assumed to be satisfied). The green compact 11 has two opposite sides included in the cross section (long-side rectangular surface) of the plate-like part 111, and is longer than the long side of the cross-section (trapezoidal face) of the frustum part 113. The two opposite sides of the cross section (short side rectangular surface) of the shape portion 112 are a solid that is equal to the short side of the cross section (trapezoid surface) of the frustum portion 113. This green compact 11 also has a frustum portion 113 (trapezoid surface) and a plate-like portion with respect to the area of the boundary surface between the frustum portion 113 (trapezoidal surface) and the plate-like portion 111 (long-side rectangular surface). It is preferable that the ratio of the area of the boundary surface to 112 (short side rectangular surface) satisfies 80% to 99.8%.

  The green compact 11 can be molded using, for example, a molding die 120 shown in FIG. The molding die 120 includes a die 103 having a through hole 103h having a flat surface, lower punches 102A to 102C that are combined to form a columnar shape, and a columnar upper punch 101. In the region of the upper punch 101 side in the through hole of the cylindrical lower punch 102B, a tapered portion 1213 similar to the tapered portion 1013 of the die 103 of the molding die 100 described above, and a linear portion 1212 connected to the tapered portion 1213, With The peripheral edge of the tapered portion 1213 of the lower punch 102B forms an opening of the through hole of the lower punch 102B. The end surface (pressing surface 102p) of the columnar lower punch 102C is inserted into the through hole of the cylindrical lower punch 102B, and the lower punch 102C is disposed so that the pressing surface 102p is positioned in the vicinity of the upper end of the linear portion 1212. By doing so, the lower punch 102B, 102C, as shown in FIG. 7, a region where the cross section becomes a trapezoidal surface, and a region adjacent to the short side of the trapezoidal surface and the cross section becomes a rectangular surface Can be formed. By inserting the lower punches 102A to 102C into the through holes 103h of the die 103, a molding space having an E-shaped cross section can be formed. By compressing the raw material powder (not shown) filled in the molding space formed by the end surface of the lower punch 102A, the pressing surface 102p of the lower punch 102C, and the end surface and peripheral surface of the lower punch 102B with the pressing surfaces 101p and 102p, Thus, a green compact 11 is obtained. The surface of the plate-shaped portion 112 of the green compact 11 and the surface parallel to the surface of the plate-shaped portion 112 in the] -shaped portion are pressure-molded surfaces 111f and 112f, and are surfaces orthogonal to the pressure direction during molding. It is. When a coil is arranged on the frustum 113, the axial direction of the coil in the green compact 11 is the pressing direction during molding. The surface (pressure forming surface 111f) parallel to the surface of the plate-like portion 112 in the] -like portion of the green compact 11 is a surface disposed on the front end side in the direction of extraction from the molding die 120.

  As shown in FIG. 8, the T-shaped core has a pressure plate portion 113 having a cross section (for example, a cross section in the axial direction of the coil) having a trapezoidal shape, like the green compact 10 of the first embodiment. The powder compact 12 can be used. The green compact 12 is connected to the weight base 113 and the long side of the weight base 113, and is connected to the plate-like part 111 whose cross section is a rectangular surface and the short side of the weight base 113. And a plate-like portion 112 having a rectangular cross section. However, the plate-like part 111 protrudes from the periphery of the frustum part 113. Therefore, when the powder compact 12 has the above cross section, the long side rectangular surface constituting the plate-like portion 111 is connected to the extended line of the long side of the trapezoidal surface. That is, the green compact 12 also has two opposite sides provided in the cross section (long-side rectangular surface) of the plate-like part 111, which is longer than the long side of the cross-section (trapezoidal surface) of the frustum part 113, Two opposing sides of the cross-section (short-side rectangular surface) of the plate-like part 112 are a solid that is equal to the short side of the cross-section (trapezoidal surface) of the frustum part 113. This plate-like portion 111 has an area S1 of the long-side rectangular surface constituting the plate-like portion 111 + an area S2 of the short-side rectangular surface constituting the plate-like portion 112 <the trapezoidal surface constituting the frustum portion 113 Satisfies area S3. The green compact 12 also includes a weight base 113 (trapezoidal surface) and a plate-like part with respect to the area of the boundary surface between the weight base 113 (trapezoidal surface) and the plate-like part 111 (long-side rectangular surface). The ratio of the area of the boundary surface with 112 (short side rectangular surface) is preferably 80% to 99.8%. Such a T-type core can also be used for a motor core, for example.

  The green compact 12 can be molded using, for example, a molding die 130 shown in FIG. 9 (A). The molding die 130 is substantially the same as the molding die 100 of the first embodiment, and includes an upper punch 101, a lower punch 102, and a die 103 having a through hole 103h. The die 103 has a tapered portion 1013. And straight portions 1011 and 1012. However, the opening side of the die 103 has a step shape, and a linear portion 1011 is provided so as to protrude in a direction orthogonal to the axis of the through hole 103h from the peripheral edge of the tapered portion 1013 on the upper punch 101 side. By using the die 103 having such a step groove, the green compact 12 having the plate-like portion 111 protruding from the frustum portion 113 can be formed as described above. The height (depth) of the straight portion 1011 (step groove) and the amount of insertion into the die 103 in the upper punch 101 may be selected so that the area S1 of the long side rectangular surface becomes a desired amount.

  Alternatively, the green compact 12 can be molded using, for example, a molding die 140 shown in FIG. 9 (B). The molding die 140 includes a die 103 having a through hole 103h having a flat surface, a cylindrical lower punch 102α and a columnar lower punch 102β that are concentrically arranged, and a columnar upper punch 101. . In a region on the upper punch 101 side in the through hole of the cylindrical lower punch 102α, a taper portion 1413 similar to the taper portion 1013 of the die 103 of the molding die 100 described above, and a linear portion 1412 connected to the taper portion 1413, With The peripheral edge of the tapered portion 1413 of the lower punch 102α forms an opening of the through hole of the lower punch 102α. The end surface (pressing surface 102p) of the columnar lower punch 102β is inserted into the through hole of the cylindrical lower punch 102α, and the lower punches 102α and 102β are arranged so that the pressing surface 102p is located in the middle of the straight portion 1412. . In this way, the lower punches 102α and 102β allow the cross section to be a trapezoidal surface as shown in FIG. 9 (B) and the short side of the trapezoidal surface to have a rectangular cross section. Regions can be formed. Further, by inserting and arranging the lower punches 102α and 103β into the through hole 103h of the die 103, the linear portion 1411 is formed between the end surface of the lower punch 102α (the surface facing the upper punch 101) and the through hole 103h of the die 103. A forming space having a T-shaped cross section can be formed.

[Reference example]
The green compact body having a specific frustum body portion and having a pressure molding surface adjacent to the frustum body has a rectangular shape on the long side of the plate-like portion 111. Even if the area S1 + the area S2 of the rectangular side surface constituting the plate-like part 112 ≧ the area S3 of the trapezoidal surface constituting the frustum part 113, and the like, the green compact 10 of the first embodiment and the like Similarly, low loss and excellent productivity. This compacted body is formed by compression molding coated soft magnetic particles having an insulating coating,
An inner part arranged in a cylindrical coil;
A first portion adjacent to the inner portion and having a first surface constituting the outer surface of the compression molded body;
A second portion having a second surface adjacent to the inner portion, constituting an outer surface of the compression molded body, and disposed opposite to the first surface;
When the axial section of the coil is taken for the inner part, the boundary line between the inner part and the first part is longer than the boundary line between the inner part and the second part,
The ratio of the area of the interface between the second part and the area of the interface between the inner part and the first part is 80% or more and 99.8% or less,
Molded with the axial direction of the coil as the pressing direction during molding,
The form which said 1st surface has been arrange | positioned at the front end side of the extraction direction from the metal mold | die for shaping | molding is mentioned. In the above aspect, since the axial direction of the coil is the pressing direction during molding, the first surface and the second surface are both pressure-molded surfaces. Typically, the said form is a solid which the said inner part is a frustum body, and said 1st part and said 2nd part are columnar bodies, such as a rectangular parallelepiped and a cylinder, like the plate-shaped part mentioned above. More specific forms include the above-described E-type core, ER-type core, T-type core, and the like, in which the long-side rectangular surface is larger than the trapezoidal surface.

[Test example]
A compacted body was produced, a reactor was produced using the obtained compacted body, and the eddy current loss of the reactor was examined. In addition, the post-treatment time and the wear amount of the molding die were examined.

In this test, as a sample No. 1, a molding die 100 shown in FIG. 2 (having a through hole 103h of the die 103 having a taper portion 1013) was used to provide a plate-like portion disposed opposite to each other. A plurality of deformed square frustum-shaped compacts having a main part were produced. As sample No. 100, a plurality of cuboid compacts were produced using another molding die. As the molding die used for sample No. 100, a die having a rectangular parallelepiped through-hole, that is, one having a uniform area from one opening to the other opening was used. All of the samples were molded in a cold state with a molding pressure of 7 ton / cm ² (≈690 MPa).

  In any sample, the raw material powder is pure iron powder (average particle size: 50 μm) manufactured by the water atomization method, and an insulating coating (thickness: about 20 nm or less) made of a metal phosphate compound by chemical conversion treatment. A coating powder composed of the formed coated soft magnetic particles was prepared. In each test, a mixed powder obtained by mixing the powdered zinc stearate with the above-described coating powder (mixed amount of zinc stearate: 0.6% by mass with respect to the whole mixed powder) was used.

  The compression molded product of sample No. 1,100 extracted from the die was subjected to heat treatment (400 ° C. × 30 minutes, nitrogen atmosphere) to obtain a heat treated product. The dimensions of the heat-treated product (one form of compacted body) of the obtained sample No. 1,100 were measured.

Sample No. 1 compacted body has one plate-shaped part with a pressure-molded surface area of 40 mm x 20 mm, the other plate-shaped part with a pressure-molded surface: 39.9 mm x 19.9 mm, each plate Part thickness: 1 mm, frustum part thickness: 10 mm, taper angle: about 0.29 °, area ratio: (39.9 mm × 19.9 mm / 40 mm × 20 mm) is about 99.3%. Here, the area of the pressure molding surface is equal to the area of the boundary surface between the plate-like portion and the frustum portion. In the cross section (longitudinal cross section) cut in the direction orthogonal to the pressure molding surface, the area of the trapezoidal surface constituting the frustum part: 399.5 mm ² is connected to the trapezoidal surface and the long side constituting each plate-like part The total area of the side rectangular surface and the short side rectangular surface is sufficiently larger than 40 + 39.9 = 79.9 mm ² , and the area ratio of the trapezoidal surface in the cross section is about 83%. Further, in another longitudinal section, the area of the trapezoidal surface: 199.5 mm ² is connected to the trapezoidal surface, the total area of the long side rectangular surface and the short side rectangular surface constituting each plate-like part: It is sufficiently larger than 20 + 19.9 = 39.9 mm ² , and the area ratio of this trapezoidal surface in the cross section is about 83%.

  The compact molded body of sample No. 100 has a pair of pressure molding surfaces of the same size as the pressure molding surface of one plate-like part of sample No. 1: 40 mm x 20 mm. It is a rectangular parallelepiped having the same thickness as the total thickness of the green compact: 12 mm.

  Each heat-treated product obtained was post-treated. This post-treatment is performed on each heat-treated product by the surface formed by the inner peripheral surface of the die (sample No. 1 is the outer peripheral surface of the plate-like portion and the frustum portion, and sample No. 100 is a pair of pressure-formed surfaces. This was performed by etching the outer peripheral surface connected to the surface with hydrochloric acid (concentration: 35 mass%).

  For sample No. 1,100, prepare multiple post-processed products and combine them in a ring to produce test cores. Each test core is composed of a coil composed of windings (same for all samples) The measurement member (corresponding to a reactor) was prepared. Here, a reactor including the pair of coil elements described in the second embodiment was manufactured. Specifically, for each sample, an inner core part was prepared using a plurality of post-processed products, and the surface subjected to post-processing (sample No. 1: outer surface of plate-like part and frustum part, sample No. 100: The produced inner core portion was inserted and arranged in each coil element so that the outer peripheral surface connected to the pair of pressure forming surfaces was opposed to the inner peripheral surface of the coil element (see FIG. 1 (C)). Samples Nos. 1 and 100 used the same specifications for the exposed core and the gap material. For this reactor, an AC-BH curve tracer was used to measure the eddy current loss We (W) at an excitation magnetic flux density Bm: 1 kG (= 0.1 T) and a measurement frequency: 5 kHz. The results are shown in Table 1. This evaluation was performed on a sample No. 1 and 100 using a reactor manufactured using the post-processed product after the post-processed processing time (etching time) described above was set to the same time. .

  In addition, the post-processing time required for the eddy current loss to satisfy a predetermined value was examined. The results are shown in Table 1. In this evaluation, after the post-treatment was performed at various treatment times, a reactor was prepared as described above, and the eddy current loss was measured. This was done by determining the processing time when obtained.

  Furthermore, the amount of wear of the molding die after continuously molding the above-mentioned compression molded product was examined. The results are shown in Table 1. Here, the wear amount was obtained by measuring the contour shape (profile) of the measurement region with a three-dimensional shape measuring machine using the following locations on the inner peripheral surface of the die as the measurement region. The measurement region is a portion in contact with the central portion in the thickness direction on the outer peripheral surface of the molded compression molded product in a state where the raw material powder is completely compressed. Then, the difference between the contour shape of the measurement region before molding and the contour shape of the measurement region after molding 20,000 compression molded products is examined, and the maximum value of this difference is defined as the wear amount (die wear amount). .

  As shown in Table 1, it can be seen that sample No. 1 using a green compact with a specific shape has a small eddy current loss even when the post-treatment time is short compared to sample No. 100. . Therefore, it can be said that the reactor of sample No. 1 has low loss even when used at a high frequency and is excellent in high frequency characteristics. The reason for this is that the compression molding of sample No. 1 reduces friction with the inner peripheral surface of the die, suppresses damage to the insulating coating of the coated soft magnetic particles and the generation of bridge portions, This is probably because the insulation was sufficiently secured. Further, it can be seen that a reactor having a smaller eddy current loss can be obtained by using the powder compact of this specific shape and keeping the post-processing time constant. The reason for this is that the compression molding of sample No. 1 has no bridge portion formed inside, and the bridge portion generated on the surface portion is sufficiently removed or insulated as described above. This is probably because the insulation between the soft magnetic particles was sufficiently ensured by suppressing damage to the coating. Furthermore, it turns out that it is possible to reduce the wear of the molding die and to extend the life of the die by using the powder compact of this specific shape. The reason for this is considered to be because the friction is reduced as described above.

  From the above, the core for the reactor of the present invention comprising the compact body of the present invention and the compact body of the present invention having a portion mainly composed of a solid body (frustum body) having a trapezoidal cross section is excellent in productivity, When used as a material for reactor cores, it can be said that the loss is low. Moreover, it can be said that the magnetic circuit component of the present invention including the green compact of the present invention is excellent in productivity due to low loss because the magnetic core material is excellent in productivity and low loss.

  In addition, this invention is not limited to embodiment mentioned above, In the range which does not deviate from the summary of this invention, it can change suitably. For example, the material and particle size of the soft magnetic particles, the material and thickness of the insulating coating, the size of the trapezoidal surface and each rectangular surface (area ratio, projected area), the planar shape, and the like can be appropriately changed.

  The green compact of the present invention can be suitably used for magnetic core materials of various magnetic circuit components (reactors, transformers, motors, choke coils, etc.), in particular, magnetic core materials having excellent high frequency characteristics. The magnetic circuit component of the present invention can be suitably used for various reactors (on-vehicle components, components for power generation / transforming equipment, etc.). In particular, the magnetic circuit component of the present invention can be suitably used for a reactor provided in an in-vehicle power conversion device such as an in-vehicle converter mounted on a vehicle such as a hybrid vehicle, an electric vehicle, or a fuel cell vehicle. The reactor core of the present invention can be suitably used as a material for the magnetic core of the magnetic circuit component of the present invention such as the reactor described above.

1 Reactor 2 Coil 2w Winding 2a, 2b Coil element 2r Connection
3 Magnetic core 31 Inner core 31m Core piece 31g Gap material 32 Exposed core
10,11,12 Compact body 111,112 Plate part 111f, 112f Press-molded surface
111s Long side rectangular surface 112s Short side rectangular surface 111o, 112o, 113o Outer peripheral surface
113 Weight base 113s Trapezoidal surface
1111,1112 Rectangular surface 1113 Trapezoidal surface
100,110,120,130,140 Mold for molding
101 Upper punch 101p, 102p Press surface
102,102A, 102B, 102C, 102α, 102β Lower punch 103 Die 103h Through hole
103i Inner peripheral surface 1011,1012,1212,1411,1412 Straight part
1013,1213,1413 Taper 104 Core rod
P Raw material powder

Claims (8)

A compacted body formed by compression-molding coated soft magnetic particles having an insulating coating,
As a cross section of at least a part of this green compact,
A trapezoidal surface having a long side and a short side opposed to each other;
A long side rectangular surface connected to the long side of the trapezoidal surface;
Having a surface composed of a short side rectangular surface connected to the short side of the trapezoidal surface;
The compacted body, wherein an area of the trapezoidal surface is larger than a total area of the long side rectangular surface and the short side rectangular surface.   When the boundary surface between the trapezoidal surface and the long side rectangular surface is the first surface, and the boundary surface between the trapezoidal surface and the short side rectangular surface is the second surface, the first surface and the first surface 2. The green compact according to claim 1, wherein the green compact is formed such that a direction perpendicular to at least one of the two surfaces is a pressing direction.   3. The green compact according to claim 2, wherein both the surface parallel to the first surface and the surface parallel to the second surface are pressure forming surfaces.   When the boundary surface between the trapezoidal surface and the long side rectangular surface is the first surface, and the boundary surface between the trapezoidal surface and the short side rectangular surface is the second surface, the area of the first surface The green compact according to any one of claims 1 to 3, wherein a ratio of the area of the second surface to 80% or more and 99.8% or less. The portion having the trapezoidal surface is used in a place where a cylindrical coil is disposed,
5. The green compact according to any one of claims 1 to 4, wherein a surface constituting a hypotenuse of the trapezoidal surface is disposed so as to face an inner peripheral surface of the coil.   A reactor core comprising the green compact according to any one of claims 1 to 5. A magnetic circuit component comprising a magnetic core and a cylindrical coil disposed in a part of the magnetic core,
The magnetic core includes an inner core portion disposed in the coil, and an exposed core portion that is exposed from the coil and forms a closed magnetic path together with the inner core portion,
6. The magnetic circuit component, wherein the inner core portion includes the green compact according to any one of claims 1 to 5.   8. The magnetic circuit component according to claim 7, wherein the magnetic circuit component is a reactor.

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