JP2015079902A - 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, P2, 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, P2; and molding a mold resin body M at a periphery of the reactor precursor Rm. A buffer material A is arranged on a surface of the core CR before the rein injection, and the reactor precursor Rm is pressed with the presser pin P2 with the buffer material A interposed 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, when the separation between the resin injection hole and the holding pin is less than half of the width of the manufactured reactor, a buffer material is disposed on the surface of the core before resin injection In addition, the reactor precursor is pressed by a pressing pin through a buffer material.

  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 reactor is less than half of the width of the manufactured reactor, a buffer material is disposed on the surface of the core before resin injection, and the reactor precursor is pressed with a pressing pin through the buffer material. As a result, the restraint of the mold resin body by the core is released, and it becomes difficult to cause a thermal deformation difference between the buffer material side portion and the outer peripheral surface portion of the mold resin body, and the pin hole in the mold resin body of the conventional reactor is the starting point This eliminates the occurrence of cracks.

  The resin injected by the buffer material does not enter the concave and convex recesses on the core surface, and the deformation performance of the buffer material also helps, resulting in a difference in thermal deformation between the buffer material side portion and the outer peripheral surface portion of the molded resin body. It becomes difficult.

  Note that the number of pressing pins attached to the upper mold is arbitrary, and may be one or more. For any number of pressing pins, if the spacing between the pressing pin and the resin injection hole is 1/2 or less of the width of the reactor, a cushioning material should be provided at least on the surface of the core in the region where the pressing pin is located. That's fine.

  Here, the applied cushioning material is preferably bonded to the core surface (because it does not move due to resin pressure), but may be non-bonded. Also, it is good to use a buffer material of thermosetting resin material so as not to melt with the injected resin, and the thickness of the buffer material should be a thin sheet material of 0.5 mm or less so as not to impair the fluidity of the injected resin. In addition, a sheet material having a low static friction coefficient: μ (preferably 0.45 or less for the same material) is preferable.

  Since the manufacturing method of the present invention is to manufacture a reactor by injecting resin into a mold by a molding method similar to the conventional method with a cushioning material disposed on a part of the core surface, the manufacturing cost is reduced. A reactor in which the generation of cracks is suppressed can be manufactured without any increase.

  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 holding pin is less than or equal to 1/2 the width of the manufactured reactor, By placing a buffer material on the surface of the core and pressing the reactor precursor with a pressing pin through the buffer material, the restriction of the mold resin body by the core is released, and the buffer resin side portion and the outer periphery of the mold resin body A difference in thermal deformation at the surface portion is unlikely to occur, and the occurrence of cracks starting from pin marks in the mold resin body can be effectively eliminated.

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 P2 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 P2 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 cylindrical pin member is also applied to the pressing pin P2 that satisfies the relationship of t2 ≦ 2 / t. However, the pressing pin P2 and the core CR are not in direct contact with each other, but a buffer material A having a low static friction coefficient μ is disposed on the surface of the core CR, and the buffer material A is pressed by the pressing pin P2.

  Here, the buffer material A is a thermosetting resin material such as PAI, PI, and PTFE having a continuous heat resistance temperature of 150 ° C. or higher so as not to melt in the injected resin, and the fluidity of the injected resin is impaired. A thin sheet material with a thickness of 0.5 mm or less is preferable. Further, a sheet material having a low coefficient of static friction: μ (preferably 0.45 or less for the same material) is preferable.

  A molding die K having a lower mold Ku and an upper mold Ka having the above-described configuration is prepared, and two coils CL are disposed in two locations of the annular and magnetic core CR in the lower mold Ku, and at least one of the core CRs is provided. The reactor precursor Rm in which the buffer material A is disposed in the part is accommodated.

  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 holding pin P3, the upper mold Ka is closed on the lower mold Ku, and the holding pins P1 and P2 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 pin hole B2 is formed by a pressing pin P2 at a position where the distance between the hole Ka2 and the projection position T2 is t2 (t2 ≦ 2 / t).

  Although the pin hole B2 is formed at a position where the distance between the resin injection hole Ka2 and the projection position T2 is t2 (t2 ≦ 2 / t), the buffer material A is located in the back (core side) of the pin hole B2. By interposing, it becomes difficult for the thermal deformation difference to occur between the interface portion of the mold resin body M with the core CR and the outer peripheral surface portion on the opposite side. The deformation can be absorbed, and the generation of cracks is effectively suppressed.

  In the illustrated reactor manufacturing method, a buffer material A is disposed on the surface of the core CR before resin injection in a region having a presser pin with a short distance from the resin injection hole, and the presser pin is interposed via the buffer material A. Production including the production of the molding die, because the reactor precursor Rm is pressed at P2 and the reactor is produced by injecting the resin into the die by the same molding method using the same molding die K as before. The reactor R in which the generation of cracks is suppressed can be manufactured without increasing the cost. In the illustrated example, the cushioning material A is disposed only on the core surface on the pressing pin P2 side, but it is needless to say that the cushioning material may be disposed on the core surface on the pressing pin P1 side.

  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, A ... Buffer material, M ... Mold resin body, B1, B2 ... Pin hole (pin mark), K ... Mold, Ka ... Upper die, Ku ... Lower mold, P1, P2, P3 ... Holding 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.
If the distance between the resin injection hole and the holding pin is less than half the width of the reactor to be manufactured, a buffer material is disposed on the surface of the core before resin injection, A method of manufacturing a reactor in which a reactor precursor is pressed by a holding pin.

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