JP2012174904A - Manufacturing method of molded coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a highly reliable molded coil having excellent characteristics at a low cost, in which the mold structure is not complex, the molding process can be simplified, and variations in the mold position of a winding and the dimensions are small.SOLUTION: In the manufacturing method of a molded coil where a coil is sealed of a mold resin produced by kneading a resin and a powder of a magnetic material by using plastic compression molding, a pellet large enough to penetrate a winding core is made, a slidable punch is provided on the extension of the winding core of the winding to be set in the mold cavity, at least a portion of the pellet is inserted into both the female die of the punch and the winding core, and then the mold material is fused and compression molded.

Description

  The present invention relates to a method for manufacturing a molded coil using a plastic compression molding method.

  Conventionally, a molded coil in which a coil is wound around a core such as a ferrite core and sealed with a magnetic molding material has been widely used. Conventional mold coil molding methods are performed using transfer molding (transfer molding) or injection molding (injection molding).

  Conventional molding materials using transfer molding and injection molding have not been able to produce a material with sufficiently high relative permeability while maintaining fluidity, so there are a lot of monolithic molding coils that do not use a magnetic material as a core to obtain inductance. The number of windings is required and the DC resistance becomes very high, and the winding volume tends to increase, so the cross-sectional area of the magnetic material is limited and the DC superimposition characteristics are also very low, which satisfies the characteristics as a power inductor I couldn't.

On the other hand, an inductor in which a granulated powder such as a binder, a magnetic powder, and a winding are integrated by powder compression molding is disclosed (for example, see Patent Document 1). Furthermore, a metal iron-based magnetic power inductor using this method has been highly evaluated.

  However, since the powder compaction method integrates the powder by pressurization, a large pressure is required, which causes a large damage to the wound winding. Further, since the volume of the filled powder is greatly changed by compression, a variation in molding density or the like occurs depending on the presence or absence of an internal winding. Usually, in order to alleviate this, the volume of the portion without winding is more than necessary on the magnetic circuit.

  Therefore, the applicant proposed in Japanese Patent Application No. 2008-4005 filed earlier that a winding method is embedded with high accuracy by a plastic molding method, a material loss is small, and a low-cost production method for a high-performance molded coil is proposed.

  In addition, in the Japanese Patent Application No. 2009-267350 filed earlier, the applicant can embed the winding with higher accuracy without separating the supply material, forming a method for producing a high-performance molded coil with low material loss and low cost. Proposed.

JP 2008-4005 A JP 2009-267350 A

  In the previously filed Japanese Patent Application No. 2008-4005, the materials to be supplied are divided into two parts, the molding process is complicated, and in the case of supplying the material in the form of powder, the entrapment of bubbles easily occurs in the molded body.

  Also, in the previously filed Japanese Patent Application No. 2009-267350, it is a manufacturing method of a coiled integral type coil using a plastic compression molding method, and the punch sliding with the comparison type cavity 1 can be slid independently. A method in which the mold resin is formed in stages after holding the winding at the position specified by the positioning pin 2 and the support pin 3 using a mold constituted by the positioning pin 2 and the support pin 3. It is.

The mold resin is pressurized in several stages, and usually after one stage of pressurization, the positioning pin 2 is moved to a predetermined position, and the second stage of pressurization is performed. Finally, the support pin 3 is moved to a predetermined position, and the third stage pressurization is performed.

  In this way, the pressurization divided into several degrees complicates the process, which increases the equipment cost and man-hours.Since the support pins and positioning pins slide while in direct contact with the mold resin, the pins and guides wear. There is a severe problem with mold life.

In addition, since resin and kneaded material flow into and adhere to the gap between each pin and the pin guide, man-hours are required for the peeling process, cleaning and removal of foreign matter, etc., and the mold structure becomes large due to mold wear and backlash. Therefore, it is necessary to use a high-hardness material with little wear and the cost is high.

Forming a magnetic mold material into a shape capable of penetrating the winding core of the air-core coil in a method for producing a mold coil in which the air-core coil is sealed with a magnetic mold resin obtained by kneading resin and magnetic powder, etc. A mold having a pressure punch that slides on both sides of the core extension line of the cavity in the mold, at least a part of the molding material enters the punch female mold, and in the core of the air-core coil An integrated mold coil having a step of setting in an inserted state and a step of pressure molding by a plastic compression molding method by sliding a pressure punch after at least a part of the molding material is melted is manufactured. It is characterized by that.

A method for manufacturing a mold coil, wherein a gap 11 through which a large amount of resin is selectively discharged is intentionally provided in a mold.

  The method for manufacturing a molded coil according to the present invention is to prepare cylindrical pellets 16 prepared by, for example, powder compression molding so as to fit in the core of the central support winding 4 set in the mold. The pellet 16 is inserted so as to pass through the winding core and enter the upper punch female mold portion 13 and the lower punch female mold portion 14 formed in the mold, and the upper punch 17 and the lower punch 15 are inserted in the molten state. A coil-integrated mold coil is formed by sliding.

In the manufacturing method, since the pellets 16 once supplied into the mold are formed into, for example, a cylindrical shape, it is possible to remove the internal bubbles when forming the supply material, and it is possible to reduce the bubbles in the mold coil.

In this manufacturing method, the upper punch or the lower punch can be moved independently or synchronously, so that flow with less damage to the winding and displacement of the winding position is possible depending on the mold resin flow pressure and flow method. Thus, for example, in a winding structure such as the central support winding 4, the positional deviation of the winding and the winding stress can be extremely reduced by supporting the center and allowing the mold resin to flow in the same manner from above and below. .

Furthermore, since the position of the winding of the pellet 16 can be defined like the positioning pin 2, it is possible to reduce variations in the characteristics and appearance of the mold coil, and it is complicated in the mold such as the positioning pin. The factors that make multiple mechanisms can be reduced, and mold costs and maintenance costs can be reduced.

  If either the upper punch or the lower punch is in a pressurized state, it is possible to selectively discharge the mold resin containing a large amount of the resin component from the gap 11 provided in the mold. It is only necessary to make a diaper on one of the upper and lower surfaces only on one surface, making it easy to handle surface-mounted coils with severe height restrictions. For example, if it is protruding, only the protruding portion needs to be cut, and even if it is recessed, it is a part, so that the influence on the characteristics is reduced.

FIG. 1 is a perspective view showing a positioning pin support pin structure of a mold used for explaining a conventional construction method. FIG. 2 is a view of a winding of a central support structure having a terminal at the center in the thickness direction of the winding used in Example 1 of the present invention. FIG. 3 is a view of a winding having a support structure under the winding used in Embodiment 2 of the present invention. FIG. 4 is a cross-sectional view for explaining a method of manufacturing a molded coil used in the embodiment of the present invention.

  In the method for producing a mold coil according to the present invention, a mold material, which is a magnetic material kneaded material made of magnetic powder and a thermosetting resin, is formed into a size that fits into a winding core. When the cross-sectional shape of the winding core is circular, it is cylindrical. When the winding core cross section is an ellipse, the cross section of the molded body is preferably close to the winding cross section as long as there is no hindrance to the insertion in the ellipse. This is because the gap between the wound wire and the molded product (pellet) that has been thrown in acts as a force that moves the winding position when the charged material does not flow uniformly during compression molding. In addition, the position of the winding core can be defined by the positions of the upper and lower punch female molds and the size of the pellets, and displacement can be prevented.

The pellets can be manufactured by a melt molding method such as extrusion molding, but it is desirable that the magnetic mold resin is once pulverized into a powder and then molded by a compression molding method. The compression molding method is desirable because the size of the molded body can be accurately determined.

Further, the number of pellets supplied into the mold may be two or more. If the length of the feed material becomes extremely large compared to the cross section, there is a problem in weight variation during molding and strength. Sometimes it is. If at least one supply material enters the punch female mold and enters the winding core, the stress that greatly moves the winding position is greatly reduced, and the position can be stabilized.

The mold has a slidable punch mold that is smaller than the upper and lower cavity surfaces. The mold may have a function of fixing the winding. For example, a mechanism for holding the winding terminal in between and a mechanism for maintaining it hollow like a support pin are conceivable. The size of the punch is similar to the size of the winding core, and ideally the upper and lower punch positions coincide. If there is no problem when the molding material is charged, the winding position can be defined by the position of the punch female die and the position of the molding material.

    In addition, the magnetic material volume ratio of the mold resin can be improved and the inductance can be increased by intentionally forming a gap for selectively discharging the mold resin component in at least a part of the cavity side with a spacer or a clearance. Can do.

The winding is set at a predetermined position in the mold so that the cross section of the winding core is approximately parallel to the punch surface. It is more desirable that the winding is processed so that the position can be easily determined. For example, there are a mechanism for pressing the cavity side surface utilizing the elasticity of the winding, a structure for supporting in the compression direction (lower support winding 6), and the like. Further, it is also conceivable that the pinching position is determined by a die by bending the terminal near the center like the central support winding 4 (FIG. 4 (a) winding set).

In addition, the winding can be maintained to some extent by using a fusion wire, etc., and can be used for edgewise winding of a flat wire or two steps of outer and outer windings (upper and lower two-stage structure with the winding start and winding ends on the outside). However, it can be tightly wound and is advantageous in terms of electrical characteristics. However, if the winding itself has a thickness or thickness that can maintain the shape, the fusing function is not necessary.

  The molding material is set so that the molding material enters both the upper and lower punch female molds with at least a part of the molding material entering the core of the set winding and at least a part of the molding material entering the punch female mold. . (Fig. 4 (b) Pellet insertion)

The mold may be set in advance in a preheated state, or may be heated after setting.

Next, the mold resin is melted. The melting temperature is selected to be an appropriate temperature above the melting temperature depending on the viscosity of the resin. Depending on the winding structure, support method, etc., the winding mold position accuracy may be improved at a relatively low viscosity and low temperature, or the mold position accuracy may be improved at a relatively low viscosity high temperature. . When the support structure and the mechanism capable of maintaining the winding position to some extent are strong, the winding mold position accuracy tends to be relatively better when the molding is performed at a relatively low temperature. Further, the heating may be divided into several stages and set according to the position accuracy.

After melting, the air core coil is molded by plastic compression molding by sliding the upper and lower punches. The sliding punch may move up and down differently or may move synchronously. When there is a structure such as a support pin in the lower part due to the support structure, it is preferable to move the punch on the upper surface first, remove the support pin after filling, and move the punch on the lower surface to perform compression molding.

When the support structure is weak, or when the support structure is in the vicinity of the center where the winding terminal is sandwiched between the molds, it is preferable that the upper and lower punches slide in synchronism and the upper and lower mold resins flow evenly.

  Either one of the pressure punches stops at a predetermined position, and it is preferable to mold by applying pressure with the other punch. In this way, the bulge or dent can be made on one side. Further, if the mold resin becomes excessive, only that portion may be removed, and if it is depressed, only the burr may be removed.

  The mold is raised to the curing temperature under pressure. However, it remains as it is when the initial punch sliding temperature is the curing temperature. In general, the curing temperature is preferably a high temperature that does not adversely affect the resin or the like. By increasing the temperature, not only the curing time is shortened, but also the viscosity is lowered, and the resin component is easily selectively discharged from the gap provided in the mold. However, if the curing time is too early, the resin discharge time is shortened and the characteristics may become unstable. Therefore, the amount of curing agent and the temperature are appropriately determined.

  The hardened mold coil is taken out from the mold by a predetermined method, and after deburring or the like, external electrodes are formed if necessary to form a mold coil. The external electrode may be a winding itself, or may be formed by connecting a material by a predetermined method by processing a metal such as a phosphor bronze plate, or by using a material such as plating or a conductive resin. May be.

After mixing 8 wt% of an epoxy resin mixture containing 92 wt% of amorphous magnetic powder and an equivalent amount of novolac type epoxy resin and phenol novolak type resin in a kneader at 110 degrees 40 minutes, add 0.1 wt% of TPP to the epoxy resin mixture. Further, after kneading for 3 minutes, the material was taken out from the kneader and cooled to obtain a plurality of kneaded masses having a diameter of about 8 cm.

The kneaded mass was coarsely pulverized to a particle size of about 2 mm with a crusher mill, finely pulverized with a hammer mill (using a 2 mmφ mesh), and passed through a sieve with an opening of 0.5 mm to obtain the raw material powder.

The mixed powder was prepared by compressing a predetermined amount of cylindrical pellets 16 using a 1.9 mmφ die.

The central support winding 4 is edgewise wound with a flat wire of 1.5 mm width and 0.7 mm width around a winding core of 2.0 mmΦ, and each central support winding terminal 5 is located at the center of the winding direction in the longitudinal direction. Processed to stick out.

As shown in FIG. 4A, the size of the cavity is 9 mm square and 3 mm high, and the upper mold 8, the middle mold 10, and the lower mold 12 are used, and a spacer is used between the middle mold 10 and the lower mold 12. A gap 11 of 40 μm is formed, and an upper punch female die portion 13 and a lower punch female die portion 14 are provided at approximately the center of each cavity of the upper die and the lower die, and a slidable upper punch 17 and lower punch 15 are inserted. It is possible to use a mold having a terminal support mechanism in which the central support winding terminal 5 just enters in the longitudinal direction, and the both ends of the installation winding 9 are accommodated in the terminal support mechanism without the upper punch 17 so that the cavity It was placed so as to fit in the center and fixed with a sandwiching mold.

    As shown in FIG. 4B, the pellet 16 is inserted from the upper part of the upper punch female part 13 through the central support winding 4 (installed winding 9) and into the lower punch female part 14 as shown in FIG. It was.

As shown in FIG. 4C, the upper punch 17 was set and heated to 100 degrees. After the mold resin was melted, the upper punch 17 and the lower punch 15 were slid while being synchronized, and the melted mold resin was filled in the cavity. In the final stage of filling, the lower punch 15 was first stopped at a position corresponding to the bottom of the mold, and then 50 kg load was applied to the upper punch 17.

With the load applied, the mold temperature was raised to 150 ° C. and the resin was cured by holding for 5 minutes, and then removed from the mold to obtain a molded coil molded body 18.

After removing burrs and the like by a predetermined method, the wire covering of the central support winding terminal 5 was removed to obtain a molded coil.

As in Example 1, the materials were kneaded and pulverized to obtain a powder compact having the same shape.

The lower support winding 6 is edgewise wound with a flat wire of 1.5 mm in width and 0.7 mm in width on a winding core of 2.0 mmΦ, crushed each end, processed to the same thickness as the heel portion, and then wound by bending. The winding was supported at the lower part of the wire, the end was processed so as to coincide with the bottom surface, and the winding itself was processed to be supported (lower support winding terminal 7).

The lower support winding 6 was set so that the folded end face of the lower support winding terminal 7 was in contact with the bottom surface of the cavity using a mold similar to that of Example 1 and having no support structure.

Similarly, the core is penetrated, and after setting the lower punch 15, the pellet is put into the lower punch female die portion 14, and the cavity upper die 8 is placed so that the pellet 16 enters the upper punch female die portion 13, and the upper punch 17 is set. did.

The mold was fixed, and after heating at 150 degrees, the upper punch 17 was first lowered to a predetermined position, and approximately half of the cavity was filled with mold resin.

Next, after moving the lower punch 15 to the bottom of the cavity and filling the cavity with the mold resin, pressurize the upper punch 17 with 50 kg and let it stand for 5 minutes to cure the resin, then remove it from the mold and remove the molded coil molded body. Obtained.

After removing burrs and the like by a predetermined method, the wire covering of the lower support winding terminal 7 was removed to obtain a molded coil.

  Winding integral molding mold coil using plastic compression molding does not require a complicated mold structure, can embed the winding with high accuracy, reduce manufacturing costs, and suppress variations in characteristics and reliability. High performance molded coil can be manufactured.

DESCRIPTION OF SYMBOLS 1 Comparison type | mold cavity 2 Positioning pin 3 Support pin 4 Center support winding 5 Center support winding terminal 6 Lower support winding 7 Lower support winding terminal 8 Upper mold 9 Installation winding 10 Middle mold 11 Gap 12 Lower mold 13 Upper punch Female part 14 Lower punch female part 15 Lower punch 16 Pellet 17 Upper punch 18 Coil molded body

Claims (2)

  Forming a magnetic mold material into a shape capable of penetrating the winding core of the air-core coil in a method for producing a mold coil in which the air-core coil is sealed with a magnetic mold resin obtained by kneading resin and magnetic powder, etc. A mold having a pressure punch that slides on both sides of the core extension line of the cavity in the mold, at least a part of the molding material enters the punch female mold, and in the core of the air-core coil A method for producing an integrated mold coil, comprising: a step of setting in an inserted state; and a step of pressure molding by a plastic compression molding method by sliding a pressure punch after at least a part of the molding material is melted.   The method for producing a molded coil according to claim 1, wherein a mechanism for selectively discharging the resin is provided in the molding die.

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