JP5035565B2 - Metal dust core manufacturing method and metal dust core manufacturing apparatus - Google Patents

Description

  The present invention relates to a method for producing a metal dust core and an apparatus for producing a metal dust core.

As a core included in the coil device, there is a metal dust core. As a conventional core, there is a ferrite core, but a metal dust core is expected from demands such as improvement of magnetic saturation and reduction of temperature dependence of DC superimposed inductance characteristics. The metal powder core is manufactured by powder compression molding as disclosed in Patent Document 1, for example, using a powder material including a metal powder and a resin material.
Japanese Patent Laid-Open No. 5-33004

  However, according to the inspection by the present inventor, it has been discovered that a short circuit occurs between the coil winding terminals drawn out to a sufficiently separated portion on the outer surface of the metal dust core.

  This invention is made | formed in view of this, and it aims at providing the manufacturing method of the metal compacting core etc. which can prevent the short circuit via a core outer surface.

  The method for producing a metal dust core according to the present invention for solving the above-described problems is a part that is responsible for defining a part of a molding chamber, and is in a direction perpendicular to a drawing direction of the molded body, A step of preparing a mold having a movable part movable in the approaching / separating direction; a step of holding the movable part in a position for maintaining a set shape of the molding chamber; and a metal powder and an insulating resin. Filling the raw material powder containing the molding powder into the molding chamber, pressurizing the raw material powder in the molding chamber, and, after pressing, moving the movable part in a direction away from the molded body; And removing the molded body from the mold after moving the movable part in a direction away from the molded body.

  Another method for producing a metal dust core according to the present invention for solving the same problem is as a part responsible for defining a part of the molding chamber, which is in a direction perpendicular to the drawing direction of the molded body. A step of preparing a mold having a movable part movable in a direction approaching / separating from the step, and a step of applying a holding force for holding the set shape of the molding chamber to the movable part; A step of filling a raw material powder containing a metal powder and an insulating resin into a molding chamber of the mold, a step of pressurizing the raw material powder in the molding chamber, and a pressure applied to the movable part. A step of reducing or removing the holding force and a step of extracting the molded body from the mold after the holding force is reduced or removed.

  An apparatus for producing a metal dust core according to the present invention for solving the same problem has a molding chamber and is a direction orthogonal to the drawing direction of the molded body as a part for defining a part of the molding chamber. A mold having a movable part movable in a direction approaching / separating from the molded body, a pressurizing part movable in an entry / retreat direction with respect to the molding chamber, and And a movable part position control means for holding the movable part at a position for maintaining the set shape of the molding chamber and for moving the movable part in a direction away from the molded body after pressing.

  Another metal dust core manufacturing apparatus according to the present invention for solving the same problem has a molding chamber and a direction orthogonal to the direction in which the molded body is drawn out as a part for defining a part of the molding chamber. A mold having a movable part movable in a direction approaching and separating from the molded body, a pressurizing part movably provided in an entry / retreat direction with respect to the molding chamber, and the movable part On the other hand, a holding force control means is provided that applies a holding force for holding the set shape of the molding chamber before pressing, and reduces or removes the holding force after pressing.

  According to the present invention described above, it is possible to prevent a short circuit through the outer surface of the core.

  The other features of the present invention and the operational effects thereof will be described in more detail with reference to the accompanying drawings.

  DESCRIPTION OF EMBODIMENTS Embodiments relating to a metal dust core manufacturing method and a metal dust core manufacturing apparatus according to the present invention will be described below with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

  Prior to describing the manufacturing method, first, a coil device including a metal dust core that is an object of the manufacturing method and a manufacturing device that implements the manufacturing method will be described. 1 and 2 are a perspective view and an exploded view of the coil device. The coil device 1 includes a metal dust core assembly 3, a winding part 5, and a pair of electrode members 7. As understood from FIG. 1, the metal dust core assembly 3 has a cubic shape that can be roughly considered as six faces, although it does not consist of a complete plane and has a surface where a void exists. Yes.

  As shown in FIG. 2, the metal dust core assembly 3 includes two metal dust cores 9 that are separated in the vertical direction of the paper (the winding winding axis direction or the direction in which the separation surface is orthogonal to the winding axis). It is configured. More specifically, each of the metal dust cores 9 includes a flat plate portion 11, a middle leg portion 13, and a pair of outer leg portions 15. The middle leg portion 13 is erected substantially at the center of the flat plate portion 11, and the winding portion 5 is arranged in such a manner as to be wound around this portion. The pair of outer leg portions 15 are also erected on the flat plate portion 11, and are arranged on opposite sides so as to sandwich the middle leg portion 13. The pair of outer leg portions 15 are sufficiently separated from the middle leg portion 13, and define a space for accommodating the winding portion 5 between the middle leg portion 13. In addition, as a metal dust core which provides this invention, it is not limited to illustration, For example, the shape where an outer leg part and a middle leg part are connected suitably is applicable. The pair of metal dust cores 9 are combined in such a manner that the flat plate portions 11 face the upper and lower outer sides to constitute the metal powder core assembly 3.

  As shown in FIGS. 1 and 2, the pair of electrode members 7 are attached to the outer surface of the outer leg portion 15 on the corresponding side of the metal dust core assembly 3. As can be understood from FIG. 1, lead portions 7 a and 7 b of electrode members 7 having different polarities are arranged on at least one outer surface of the metal dust core assembly 3 that can be generally regarded as a hexahedron. However, the metal powder core assembly 3 (metal powder core 9) is made of a material containing metal powder and a resin having high electrical resistance, and has a sufficiently high electrical insulating property. Except for this problem, there is essentially no worry of a short circuit through the outer peripheral surface of the core.

  Then, the manufacturing apparatus which implements this manufacturing method is demonstrated. FIG. 3 is a perspective view of a mold portion of the metal dust core manufacturing apparatus and shows a state in which a forming chamber is defined. FIG. 4 is a perspective view of the mold part as in FIG. 3, and shows a state when the molded body is extracted. The metal dust core manufacturing apparatus 21 includes a mold 23, a pressure unit 25, and a control unit 27. The mold 23 is constituted by, for example, a die for performing powder compression molding and a lower punch, and has at least a molding chamber 29 and a movable portion 31. The molding chamber 29 has a set shape corresponding to the molding of the metal dust core 9. In the present embodiment, a pair of movable parts 31 are provided, and each of them is a part responsible for defining a part of the molding chamber 29, and is a direction orthogonal to the drawing direction (pressing direction) Z of the molded body. It is provided so as to be movable in a direction approaching / separating from the molded body. In the illustrated example, the movable portion 31 is provided in the die portion of the mold 23, and the upper portion of the movable portion 31 extends to the upper surface of the die portion.

  The pressurizing unit 25 is constituted by, for example, an upper punch for performing powder compression molding, and is provided so as to be able to enter and leave the molding chamber 29. In the present embodiment, the control means 27 holds the movable portion 31 at a position that maintains the set shape of the molding chamber 26 before pressurization, and moves the movable portion 31 in a direction away from the molded body after pressurization. Such movable part position control is performed. As a specific example, the position of the movable part 31 before pressurization is maintained using a contact stopper or a spring provided on the movable part 31, that is, into the molding chamber 29 of the movable part 31 by the contact stopper. Is prevented from entering, and the movable portion 31 is prevented from retreating by a pressing force during pressurization by a spring. Movement of the movable part 31 after pressurization can be performed by an actuator. Alternatively, as another example, both the maintenance of the position of the movable part 31 before pressurization and the movement of the movable part 31 after pressurization can be performed by an actuator. Furthermore, the control means 27 in the present invention may be a mode in which the holding force applied to the movable portion 31 is controlled instead of directly capturing the position of the movable portion. That is, the control means 27 applies holding force control to the movable portion 31 to hold the set shape of the molding chamber 29 before pressurization and to reduce or remove the hold force after pressurization. You may make it perform. For example, as described above, a stopper, a spring, an actuator, or the like can be used as appropriate, and the control can be performed with the holding force rather than the position of the movable portion 31 as a monitoring target.

  Next, the manufacturing method of the metal powder core which concerns on this invention using the said metal powder core manufacturing apparatus is demonstrated. In the coil device using the metal dust core, as described above, because it is made of a material containing metal powder and a resin having high electrical resistance, it originally has sufficiently high electrical insulation, There is no worry of short circuit through the core outer peripheral surface. However, according to the inspection by the present inventor, it has been discovered that a short-circuit occurs between the coil winding terminals drawn to a sufficiently separated portion on the outer surface of the metal dust core. According to the analysis of the present inventor, when the molded body is extracted from the mold, the molded body rubs against the defining surface of the molding chamber in the mold, and metal particles on the surface of the molded body, that is, the outer surface of the metal dust core. This is considered to be caused by a state in which the metal layer is dragged and stretched (sagging) and approaches or comes into contact with adjacent metal particles. In other words, this is because a part of the outer surface of the metal powder core that is supposed to be exposed by the electrically insulating resin is covered with the extended metal. The present inventor believes that a short circuit may occur if such a portion is continuously generated to some extent.

  Therefore, in the present embodiment, the metal dust core is manufactured as follows. First, as shown in FIG. 5, as step S <b> 1, a mold 23 having the movable part 31 as described above is prepared. As step S <b> 2, the movable portion 31 is held at a position where the set shape of the molding chamber 29 is maintained. Alternatively, a holding force for holding the set shape of the molding chamber 29 is applied to the movable portion 31. This state is the state shown in FIG.

  Next, as step S <b> 3, raw material powder containing metal powder and insulating resin is filled into the molding chamber 29 of the mold 23. The aspect of the raw material powder is not particularly limited, and for example, a metal particle itself subjected to a resin coating treatment may be used, or a metal powder and resin simply mixed together may be used. Also good. Next, as step S4, the pressurizing part 25 is caused to enter the molding chamber 29 to pressurize the raw material powder in the molding chamber 29 to obtain a molded body (metal compact core 9). When the molding is completed, the pressurizing unit 25 is withdrawn from the molding chamber 29 and the pressurization is terminated.

  Next, as step S5, after the end of pressurization, the movable part 31 is moved in a direction away from the molded body. The mold 23 and the movable part 31 in this state are shown in FIG. That is, as shown in FIG. 4, since the corresponding surface of the movable portion 31 that was responsible for defining a part of the molding chamber 29 moves away from the molded body, a part of the defining surface of the molding chamber 29 is empty. Location 33 occurs. Or if it is the aspect which provided the retention strength in step S2, as step S5, the retention force provided with respect to the movable part 31 after completion | finish of pressurization will be reduced or removed, and the reaction force reduction with respect to a molded object will be reduced. Give part. Finally, in step S6, the molded body is extracted from the mold 23.

  According to the present embodiment as described above, when the finished molded body (metal dust core) is extracted, the friction between the molded body and the defining surface of the molding chamber is partially prevented at the portion facing the movable part. can do. For this reason, a core that can be a problem can be obtained by molding the outer surface of the core, which has been previously known to cause a short circuit, depending on the lead arrangement of the electrode member in the final coil device so as to face the movable part. As expected, the portion where the electrically insulating resin is exposed can be positively left on the outer surface, and short-circuiting via the outer surface of the core can be reliably prevented.

  Further, as a comparative aspect, the present inventor performs a process of forming a groove on a surface where a short circuit may cause a problem after the molded body is extracted from the mold, and exposes a portion that is not slid with the defining surface of the molding chamber. Aspects were also examined. However, in this aspect, the manufacturing process increases, and cracks may be induced depending on how to apply the force for grooving. Furthermore, as another comparative aspect, the present inventor has also studied an aspect in which a protrusion is raised in the molding chamber before pressing and a groove is provided in the molded body. In this case, although the process only for grooving is unnecessary, in addition to the vertical compression by the upper and lower punches, a force in the horizontal direction will be applied, which hinders proper compression coupling and the coupling is insufficient. There is a risk of causing cracks. Furthermore, as another comparative aspect, the present inventor also examined an aspect in which a protrusion is formed in the molding chamber at the time of extraction, and a scratch groove is formed by the protrusion in the process of extracting the molded body from the mold. However, even in such an embodiment, there is a risk of inducing cracks and cracks by applying a local force during extraction. As can be seen from the above, according to the present embodiment, it is possible to avoid cracks and induction of cracks without increasing the number of manufacturing steps.

  Furthermore, in the present embodiment, since the movable part is moved (reduction / removal of holding force) after the pressurization is completed, a part of the molded body in which the pressure is partially released does not occur during the pressurization. That's it. Further, since the movable part is moved before the raw material powder is filled into the molding chamber, it is possible to avoid the powder from being caught between the movable part and the mold.

  Although the contents of the present invention have been specifically described with reference to the preferred embodiments, various modifications can be made by those skilled in the art based on the basic technical idea and teachings of the present invention. It is self-explanatory.

  First, the space that appears in the molding chamber is not limited to being generated by the movable part as described above. Therefore, for example, the mold (die part) is composed of two or more separated parts, and at least when the pressure is applied, the parts are completely joined, and when the molded product is extracted, the parts are slightly separated. A mode in which the gap generated between the parts functions as a void is also possible.

  Further, the metal dust core may have a winding portion embedded therein. That is, the metal powder core in which the winding portion is embedded is obtained by filling and pressing the raw material powder in the molding chamber while the winding portion is supported in the molding chamber by the mold. Even in such an embodiment, there may be a surface where a short circuit may be a problem, and therefore the present invention can be implemented.

  In the present invention, it is important to extract the molded body after the appearance of the void (reaction force reducing portion) (reduction / removal of holding force). Therefore, for example, the pressurization may be removed after the appearance of the void (reaction force reducing portion) (reduction / removal of holding force), or the original setting shape of the molding chamber is ensured after filling with the raw material powder. You may do it.

It is a perspective view of a coil device concerning an embodiment of the invention. It is an exploded view of the coil apparatus of FIG. FIG. 3 is a perspective view of a mold portion of the metal dust core manufacturing apparatus and shows a state in which a forming chamber is defined. FIG. 4 is a perspective view similar to FIG. 3 and shows a state when the molded body is extracted. It is a flowchart which shows the manufacturing method of the metal dust core which concerns on this Embodiment.

Explanation of symbols

9 Metal Powder Core 21 Metal Powder Core Manufacturing Equipment 23 Mold 25 Pressurizing Part 27 Control Unit 29 Molding Chamber 31 Movable Part 33 Space

Claims (6)

Providing a mold having a movable part that is movable in a direction perpendicular to the drawing direction of the molded body and approaching / separating from the molded body as a part that defines a part of the molding chamber; ,
Holding the movable part in a position to maintain the set shape of the molding chamber;
Filling raw material powder containing metal powder and insulating resin into the molding chamber of the mold; and
Pressurizing the raw material powder in the molding chamber;
After pressing, moving the movable part in a direction away from the molded body; and
A metal dust core comprising: a step of moving the movable part in a direction away from the molded body to create a void in a part of a defining surface of the molding chamber and then extracting the molded body from the mold. Manufacturing method. Providing a mold having a movable part that is movable in a direction perpendicular to the drawing direction of the molded body and approaching / separating from the molded body as a part that defines a part of the molding chamber; ,
Applying a holding force for holding the set shape of the molding chamber to the movable part; and
Filling raw material powder containing metal powder and insulating resin into the molding chamber of the mold; and
Pressurizing the raw material powder in the molding chamber;
Reducing or removing the holding force applied to the movable part after pressurization; and
A method for producing a metal dust core, comprising: reducing or removing the holding force and partially generating a reaction force reducing portion in the molded body and then extracting the molded body from the mold. As a part that has a molding chamber and is responsible for defining a part of the molding chamber, it has a movable part that is movable in a direction perpendicular to the extraction direction of the molded body and in a direction approaching and separating from the molded body. Mold,
A pressurizing part provided movably in the entry / exit directions with respect to the molding chamber;
The movable part is held at a position where the set shape of the molding chamber is maintained before pressurization, and the movable part is moved in a direction away from the molded body after pressurization to form a part of the defining surface of the molding chamber. Ru cause voids apparatus for manufacturing a metal dust core having a movable portion position control means. As a part that has a molding chamber and is responsible for defining a part of the molding chamber, it has a movable part that is movable in a direction perpendicular to the extraction direction of the molded body and in a direction approaching and separating from the molded body. Mold,
A pressurizing part provided movably in the entry / exit directions with respect to the molding chamber;
A holding force for holding the set shape of the molding chamber is applied to the movable part before pressurization, and the pressurization force is reduced or removed after pressurization , and the reaction force is partially reduced in the molded body. part Ru cause, apparatus for producing metal powder core with a holding force control means. A method for producing a metal dust core according to claim 1 or 2,
The molding chamber is invariable except for a portion defined by the movable part.
Production method. The metal dust core manufacturing apparatus according to claim 3 or 4,
The molding chamber is invariable except for a portion defined by the movable part.
Manufacturing equipment.

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