JP2015079900A - Method of manufacturing reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a reactor, having a resin molding formed at a periphery of a reactor precursor, in which cracking starting at a pin mark made by a presser pin applied during the molding of the resin molding can be effectively suppressed.SOLUTION: A method of manufacturing a reactor R includes: putting a reactor precursor Rm having a coil CL formed at a part of a magnetic core CR in a form block K comprising an upper mold Ka having resin injection holes Ka1, Ka2 and presser pins P1, P4, and a lower mold Ku; injecting resin into the form block K through the resin injection holes Ka1, Ka2 while fixing the reactor precursor Rm with the presser pins P1, P4; and forming a resin molding M at a periphery of the reactor precursor Rm. A belt-like presser pin P4 which extends up to an end of the upper mold is applied when the resin injection holes and presser pins are apart from each other by 1/2 or less of the width of the reactor to be manufactured.

Description

  The present invention relates to a method for manufacturing a reactor.

  More specifically, a reactor is applied as a component of a power conversion device such as an in-vehicle DC-DC converter, as a circuit component that performs voltage step-up or step-down control in the power conversion device.

  There are various types of reactors. For example, U-type cores and I-type cores are annularly assembled via a gap and a coil is formed around them. Form in which mold resin body is formed around coil unit, form in which core-coil unit is housed in case, form in which core-coil-mold resin body unit is housed in case (between unit and case) A buffer sheet or the like).

  In particular, it is common to use a reactor composed of a core-coil-molded resin body and a reactor in which these units are housed in a case, which can be integrated in a state where the core and the coil are insulated. .

  In this method of manufacturing a reactor comprising a core-coil-mold resin body, a coil is formed in a part of a magnetic core in a mold comprising an upper mold having a resin injection hole and a holding pin, and a lower mold. The core-coil unit (reactor precursor) formed is accommodated, and the reactor precursor is fixed with a pressing pin, and the resin is injected into the mold through the resin injection hole. Patent Document 1 discloses a method for manufacturing a reactor in which a core-coil unit is accommodated in a case, resin is injected into the case, and the core-coil-molded resin body-case is integrated.

  In the molding of the mold resin body, the vicinity of the resin injection hole (also referred to as gate) is further heated in addition to the normal preheating among the surfaces of the reactor precursor. Easy to get in. And in the location which resin entered into the recessed part and hardened | cured, while the mold resin body is restrained by the core surface by an anchor effect, the surface (outer peripheral surface on the opposite side to a core interface) is not restrained. Therefore, when the mold resin body repeatedly contracts and expands due to heat, there is a difference in the amount of thermal deformation between the portion near the interface with the core and the outer peripheral surface portion of the mold resin body, resulting in cracks. There is a problem that it becomes easy.

  Among the manufactured reactors, the portion that was pressed by the pressing pin at the time of molding the molded resin body (therefore, the pin mark (pin hole) in the molded resin body) is weak in strength, but the crack described above is weak in this structure. The cracks tend to extend to the end of the mold resin body starting from the pin hole.

  More specifically, when the separation between the resin injection hole and the holding pin is long, the occurrence of cracks starting from the pin hole is small, but the pin hole when the separation between the resin injection hole and the holding pin is short. It has been found by the present inventors that the occurrence of cracks starting from is remarkable.

  This will be described with reference to FIGS. As shown in FIG. 3, a reactor precursor R ′ in which a coil CL is disposed at two locations of an annular magnetic core CR in a molding die K ′ composed of a lower die K′u and an upper die K′a. m. Here, two resin injection holes K'a1, K'a2 are opened in the upper mold K'a, and injection nozzles N1, N2 are attached to the respective resin injection holes K'a1, K'a2. Further, two pressing pins P1 and P2 are attached to the back surface of the upper die K′a, and another pressing pin P3 is attached to the side surface of the lower die K′u.

  Here, the separation between the resin injection hole K′a1 and the holding pin P1 is t1, and the separation between the resin injection hole K′a2 and the holding pin P2 is t2, and the width of the reactor R ′ (connects the two coils). The width in the direction is t, and there is a relationship of t1> 2 / t and t2 ≦ 2 / t between the distances t1 and t2 and the width of the reactor R ′. FIG. 3 also shows projection positions T1 and T2 of the two resin injection holes K′a1 and K′a2 on the surface of the reactor precursor R′m.

  Reactor precursor R′m accommodated in molding die K ′ is fixed by pressing pins P3 from the side, and further fixed by pressing pins P1, P2 from above. In this state, by injecting resin through the nozzles N1 and N2 and the resin injection holes K′a1 and K′a2 (X1 direction), the resin spreads in the mold K (X2 direction) and the reactor precursor R ′. provided around m.

  The injected resin is cured to mold the mold resin body M, and the reactor R ′ including the core-coil-mold resin body is manufactured. In the reactor R ', pin holes B1, B2, and B3 due to the pressing pins P1, P2, and P3 remain. Further, the separation between the projection position T1 and the pin hole B1 is t1 like the separation between the resin injection hole K′a1 and the holding pin P1, and the separation between the projection position T2 and the pin hole B2 is from the resin injection hole K′a2. It is t2 similarly to the separation between the pressing pins P2.

  In this case, as described above, cracks starting from the pin hole B1 having a relationship of t1> 2 / t are hardly generated, but starting from the pin hole B2 having a relationship of t2 ≦ 2 / t. The crack C is easily generated.

  Here, Patent Document 2 discloses a technique in which a buffer member having a Young's modulus lower than that of the mold resin body is interposed between the core and the coil in order to suppress cracks generated in the mold resin body interposed between the core and the coil. Has been. However, even though this technique is effective in suppressing cracks generated in the mold resin body between the core and the coil, it does not lead to suppression of cracks generated in the mold resin body starting from the pin holes described above.

JP 2012-119545 A

  The present invention has been made in view of the above-described problems, and in a reactor in which a mold resin body is molded around a reactor precursor, a crack starting from a pin mark by a pressing pin applied at the time of molding the mold resin body It aims at providing the manufacturing method of the reactor which can suppress effectively.

  In order to achieve the above object, a method of manufacturing a reactor according to the present invention includes a coil formed on a part of a magnetic core in a mold including an upper mold having a resin injection hole and a pressing pin, and a lower mold. In the state where the reactor precursor is contained, the reactor precursor is fixed with the pressing pin, the resin is injected into the mold through the resin injection hole, and the mold resin body is molded around the reactor precursor to form the reactor. In the manufacturing method of the reactor, the strip-shaped pressing pin extending to the end of the upper mold is applied when the distance between the resin injection hole and the pressing pin is 1/2 or less of the width of the manufactured reactor. To do.

  The manufacturing method of the reactor of the present invention is a separation between the resin injection hole and the pressing pin (in other words, the projection position of the resin injection hole formed on the surface of the reactor precursor and the pressing position of the pressing pin on the surface of the reactor precursor. When the width of the manufactured reactor is less than half of the width of the manufactured reactor, a slit is formed in the molded resin body by applying a band-shaped pressing pin extending to the end of the upper mold. The generation | occurrence | production of the crack which started from the pin hole in the mold resin body of this reactor is eliminated.

  By forming a slit extending to the end of the surface of the mold resin body, a difference in thermal deformation between the interface portion with the core of the mold resin body and the outer peripheral surface portion on the opposite side hardly occurs, As a result of the deformation of the mold resin body in the peripheral part being absorbed by the slit, the occurrence of cracks is suppressed.

  Note that the number of pressing pins attached to the upper mold is arbitrary, and may be one or more. Regardless of the number of pressing pins, if the spacing between the pressing pin and the resin injection hole is ½ or less of the width of the reactor, the pressing pin may be a strip-shaped pressing pin extending to the end of the upper mold. .

  In the manufacturing method of the present invention, a reactor is manufactured by injecting resin into a mold by a molding method similar to the conventional one using a molding die having an upper die to which a band-shaped pressing pin extending to the end of the upper die is applied. Therefore, it is possible to manufacture a reactor in which the generation of cracks is suppressed without increasing the manufacturing cost.

  As can be understood from the above description, according to the method for manufacturing a reactor of the present invention, when the separation between the resin injection hole and the pressing pin is 1/2 or less of the width of the manufactured reactor, the end of the upper mold By applying the belt-like pressing pin extending to the portion, it is possible to effectively eliminate the occurrence of cracks starting from the pin mark in the mold resin body.

It is the schematic diagram explaining the manufacturing method of the reactor of this invention. It is the perspective view which showed the reactor manufactured with the manufacturing method of FIG. It is the schematic diagram explaining the manufacturing method of the conventional reactor. It is the perspective view which showed the reactor manufactured with the manufacturing method of FIG.

  Hereinafter, an embodiment of a reactor manufacturing method of the present invention will be described with reference to the drawings.

(Embodiment of manufacturing method of reactor)
FIG. 1 is a schematic diagram illustrating a method for manufacturing a reactor according to the present invention, and FIG. 2 is a perspective view illustrating a reactor manufactured by the manufacturing method of FIG.

  First, the structure of the shaping | molding die used when manufacturing a reactor is demonstrated.

  The mold K is composed of a lower mold Ku that accommodates the reactor precursor Rm and an upper mold Ka that is placed on the lower mold Ku. The upper mold Ka has a longitudinal direction (perpendicular to the width direction). Resin injection holes Ka1 and Ka2 are opened at two locations in the direction of the resin injection, and resin injection nozzles N1 and N2 are attached to the resin injection holes Ka1 and Ka2, respectively.

  Two pressing pins P1 and P4 are attached to the back surface of the upper die Ka, and another pressing pin P3 is also attached to the side surface of the lower die Ku.

  Here, the separation between the resin injection hole Ka1 and the holding pin P1 is t1, the separation between the resin injection hole Ka2 and the holding pin P4 is t2, the inner width of the lower mold Ku (the length in the short direction, the mold The width of the reactor manufactured with the resin body is t, and t1> 2 / t and t2 ≦ 2 / t between the distances t1 and t2 and the inner width t of the lower mold Ku of the mold. There is a relationship.

  A cylindrical pin member is applied to the pressing pin P1 that satisfies the relationship t1> 2 / t. On the other hand, a belt-like pressing pin extending to the end portion of the upper die Ka is applied to the pressing pin P4 that satisfies the relationship of t2 ≦ 2 / t. The extending direction of the band-shaped pressing pin P4 is preferably opposite to the direction toward the resin injection hole Ka2 (the direction reversed 180 degrees).

  Here, the width of the belt-shaped pressing pin P4 is preferably set to a width equal to or smaller than the cross-sectional diameter of the cylindrical pressing pin P1, and is preferably set to 5 mm or less, and preferably set to 3 mm or less. This is because by narrowing the width of the slit (pin mark) formed in the finally obtained mold resin body, the ratio of the structural weak part can be minimized while absorbing the thermal deformation around the slit.

  A reactor precursor comprising a lower mold Ku and an upper mold Ka having such a configuration, and having two coils CL disposed at two locations of the annular and magnetic core CR in the lower mold Ku. Contains the body Rm.

  Here, the core CR constituting the reactor precursor Rm has a substantially annular shape in a plan view, and the ends of the two U-shaped cores are directly connected to each other via a gap plate or without a gap plate. Form that is fixed to the whole with an adhesive and formed into an annular shape, or form that the two U-type core and I-type core are fixed with an adhesive via a gap plate, and formed into an annular shape as a whole Etc.

The U-shaped core and the I-shaped core are formed from a powder magnetic core formed by press-molding magnetic powder. When a gap plate is used, this is molded from ceramics. As this magnetic powder, iron, iron-silicon alloy, iron-nitrogen alloy, iron-nickel alloy, iron-carbon alloy, iron-boron alloy, iron-cobalt alloy, iron-phosphorus alloy, An iron-nickel-cobalt alloy, an iron-aluminum-silicon alloy, or the like can be used. The gap plate can be formed of ceramics such as alumina (AL ₂ O ₃ ) or zirconia (ZrO ₂ ). If the electromagnetic characteristics of the reactor, that is, the inductance can be ensured with the structure without the gap plate, the interposition of the gap plate between the cores is unnecessary.

  For example, an insulating material having a coil CL formed around a bobbin is disposed around the core CR.

  The reactor precursor Rm is accommodated in the lower mold Ku, the horizontal movement of the reactor precursor Rm is restricted by the pressing pin P3, the upper mold Ka is closed on the lower mold Ku, and the pressing pins P1 and P4 are used. Restrains the vertical movement of the reactor precursor Rm. FIG. 1 shows projection positions T1 and T2 on the surface of the reactor precursor Rm in the two resin injection holes Ka1 and Ka2.

  Next, by injecting resin through the nozzles N1 and N2 and the resin injection holes Ka1 and Ka2 (X1 direction), the resin spreads in the mold K (X2 direction) and is cured, as shown in FIG. The reactor R in which the mold resin body M is molded around the reactor precursor is manufactured.

  Here, as a material of the mold resin body M, a glass fiber, a mineral (talc, calcium carbonate, mica, etc.), a heat radiation filler (alumina, magnesium oxide, etc.), etc. in a matrix resin such as polyphenylene sulfide, polyamide, liquid crystal polyester, etc. A material containing is applied.

  In the mold resin body M constituting the reactor R, a pin hole B1 is formed by the holding pin P1 at a position where the distance from the projection position T1 of the resin injection hole Ka1 is t1 (t1> 2 / t), and the resin injection A slit S extending to the end of the mold resin body M by a band-shaped pressing pin P4 is formed at a position where the distance from the projection position T2 of the hole Ka2 is t2 (t2 ≦ 2 / t).

  A slit S extending to the end of the mold resin body M is formed at a position where the distance between the resin injection hole Ka2 and the projection position T2 is t2 (t2 ≦ 2 / t). A difference in thermal deformation between the interface portion with the core CR and the outer peripheral surface portion on the opposite side hardly occurs, and the slit S can absorb the deformation of the mold resin body M in the peripheral portion, and the generation of cracks is effective. Is suppressed. In addition to this, by reducing the width of the slit S as much as possible, the proportion of structural weak parts in the mold resin body M can be reduced.

  The method of manufacturing the reactor shown in the figure relates to a pressing pin attached to the upper die Ka, and an upper die Ka to which a belt-like pressing pin P4 extending to the end of the upper die Ka is applied to a pressing pin that is short from the resin injection hole. Since the reactor is manufactured by injecting the resin into the mold by the same molding method as the conventional one using the molding die K having the above, the occurrence of cracks without increasing the manufacturing cost including the production of the molding die. The suppressed reactor R can be manufactured.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

  R ... Reactor, Rm ... Reactor precursor, CL ... Coil, CR ... Core, M ... Mold resin body, B1 ... Pin hole (pin mark), S ... Slit (pin mark), K ... Mold, Ka ... Upper mold , Ku: Lower mold, P1, P3: Pressing pin, P4: Pressing pin (band-shaped pressing pin), Ka1, Ka2 ... Resin injection hole, N1, N2 ... Nozzle, T1, T2 ... Projection position of resin injection hole

Claims (1)

A reactor precursor in which a coil is formed in a part of a magnetic core is accommodated in a molding die composed of an upper die having a resin injection hole and a pressing pin, and a lower die,
In the reactor manufacturing method in which a resin is injected into a molding die through a resin injection hole in a state where the reactor precursor is fixed with the pressing pin, and a reactor is manufactured by molding a mold resin body around the reactor precursor.
A reactor manufacturing method in which a strip-shaped pressing pin extending to an end portion of an upper mold is applied when the separation between the resin injection hole and the pressing pin is 1/2 or less of the width of the manufactured reactor.

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