JPH02248226A - Production of coil molded with magnetic resin - Google Patents

Abstract

PURPOSE:To avoid the deformation of a coil resulting from pressure by selecting the ratio of the sum total of the opening area of a first injection gate for a cavity to the sum total of the opening area of a plurality of second injection gates for the cavity nearly in correspondence with the ratio of the filling volume of magnetic resin into a coil to the filling volume of magnetic resin in the outer circumferential part of the coil. CONSTITUTION:In the case of injection molding of magnetic resin for a coil 2, an injection gate of resin for the cavity 12 of a mold 11 is constituted of both a first injection gate 17c and a plurality of second injection gates 17S1, 17S2, 17S3... so that the gates are opposed to the center part and the outer circumferential part of the coil 2. The ratio Sc/Ss of opening areas is allowed to correspond to the ratio Vc/Vs of filling volume of resin in the inside and the outer circumferential part of the coil 2. For example, the following equation is held, Sc/Ss=Vc/Vs. Thereby both amount of resin filled into the coil 2 and the amount of resin filled to the outer circumferential part thereof are held at the prescribed ratio in correspondence with the respective volumes. Therefore, resin is filled in a state of equilibrium.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a magnetic resin molded coil used for various devices, inductance elements as circuit elements, choke coils, and the like.

[Summary of the Invention] The present invention relates to a method for manufacturing a magnetic resin molded coil, and includes a method for manufacturing a magnetic resin molded coil. The magnetic resin is mainly fed into the coil described in -l- from at least one first injection gate provided, and a plurality of second injection gates provided facing the outer circumference of the coil are The magnetic resin is mainly sent from the gate to the outer periphery of the coil, and the sum of the opening area of the first injection gate to the cavity and the sum of the opening L1 area of the plurality of second injection gates to the cavity are The ratio is selected in accordance with the ratio of the filling volume of the magnetic resin within approximately 21 ils and the filling volume of the magnetic resin at the outer periphery of the coil. To improve yield, improve reliability, and stabilize characteristics by avoiding deformation of a coil due to large pressure or destruction of insulation coating of a coil conductor.

[Conventional technology]

BACKGROUND OF THE INVENTION Generally, in various coils including general inductance elements, a sintered ferrite core is used as the magnetic core, and the coil is wound around this. In this case, the core is prone to cracking or chipping due to dropping or impact with other objects, but the characteristics are not affected.

In addition, when using a so-called drum core with an H-shaped or H-shaped cross section as the core, the magnetic path does not constitute a closed magnetic path, so the leakage magnetic field generated from the coil may affect other various circuit elements or equipment. This has the disadvantage of causing To solve this problem, methods such as using a pot-shaped core have been taken, but in this case, there are disadvantages such as complicated assembly and manufacturing.

[Problem to be solved by the invention]

The present invention aims to provide a magnetic molded coil with improved characteristics in order to solve problems such as core loss and breakage [11] in coil elements as described above, and complexity of assembly when forming a closed magnetic circuit. This makes it possible to improve stability, reliability, and yield.

” A possible solution to both problems is to embed the coil in magnetic resin. As shown in Fig. 4, which is an enlarged cross-sectional view, a magnetic resin mold containing soft magnetic powder (
The coil (2) is embedded in the coil (2).
) and its outer periphery may be covered with a magnetic resin molding l''1) mixed with magnetic powder. According to such a configuration, a relatively flexible Since the coil (2) is wrapped in a magnetic resin mold (1) that is highly durable and therefore less likely to chip or crack, it is mechanically protected and is entirely covered by the magnetic material of the mold (1). As a result, a closed magnetic circuit configuration is achieved, and a magnetic shielding effect is obtained that prevents leakage of magnetic flux from the coil (2) from leaking to the outside.Also, it is excellent in mass production. has.

When obtaining such a magnetic resin molded coil, injection molding is preferable for manufacturing. That is, in this case,
The coil (2) is placed in the center of a mold cavity, and magnetic IM resin is injected into the cavity to form a resin mold that envelops the coil (2).

In this case, the magnetic resin used is, for example, a resin mixed with Ferrai 1 powder in an amount of 70% by volume or more, but this magnetic resin has relatively poor fluidity. On the other hand, the injection molding is carried out at a pressure of, for example, 1 at 300"C.
This is a large pressure of ton/cIa, and if the pressure of the resin injected into the coil during injection injection into the cavity is not uniform in each part, the large pressure will be applied locally and the coil will be formed into a cylindrical shape in advance. coil (2)
) may be distorted, or the coil (2) may not be placed on the central axis of the mold (1) and may become eccentric, resulting in a part of the coil (2) being exposed outside the resin mold. In (2), the wire elements are strongly rubbed together, causing peeling of the insulation coating, causing part of the coil to be short-circuited, resulting in variations in characteristics between products, decreased reliability, and the generation of defective products, resulting in lower yields. This results in a decline. In particular, the imbalance in pressure between the inside and outside of the magnetic resin coil causes two types of disadvantages.

In the present invention, when obtaining a mold coil with such a magnetic resin mold by injection molding, 1) a series of decreases in yield, 1), 1) and 1) non-uniformity are avoided. The present invention provides a method for manufacturing a malt coil, which is intended to effectively avoid a decrease in double-n property.

[Means for Solving the Problems] The present invention is explained in FIG. 4, as shown in FIG. As shown above, the coil (2) is placed inside the magnetic resin mold (1).
In order to obtain a magnetic resin molded coil in which is embedded a coil (2) disposed in a cavity (12) of a mold (11), at least a The magnetic resin is mainly fed into the coil (2) from one first injection gate (17c), and a plurality of second injection gates are provided facing the outer periphery of the coil (2).
(17s+), (17sx), (17s3)”・
・The magnetic resin is mainly fed into the outer circumference of the coil (2) from the first injection gate (17e) to the cavity (12), and the total opening area Sc to the cavity (12) and the plurality of second injection gates. (17s +), (17sz)
, (17s3) ++ The ratio Sc/Ss of the total opening area Ss to the cavity (12) of ++ is approximately equal to the filling volume ■c of the magnetic resin in the coil (2) and the magnetic resin on the outer periphery of the coil (2). The selection is made in accordance with the ratio Ve/Vs to the filling volume Vs.

[Effect]

As described above, in the method of the present invention, when injection molding the magnetic resin onto the coil (2), the injection gate of the resin into the cavity (12) of the mold (11) is connected to the coil (2).
), a first injection gate (17c) and a plurality of second injection gates (17s,
), (17sz), (1733) "",
The opening area ratio Sc/Ss is calculated as the resin filling volume ratio Vc/Vs between the inside of the coil (2) (inside the center hole (2h)) and the outer peripheral part.
For example, by setting Sc/5s=Vc/Vs, the amount of resin filled into the coil (2) and the amount of resin filled into the outer periphery can be set at a predetermined ratio according to their respective volumes. Therefore, since the resin is filled in a balanced manner, an unbalanced pressure is not applied to the coil (2) from the outer periphery toward the inside, or from the inside toward the outer periphery due to resin injection. This can be effectively avoided. Therefore, it is possible to avoid deformation and eccentricity of the coil (2) based on this pressure, and furthermore, it is possible to avoid peeling off of the insulation coating due to friction between the coil wire elements due to unbalanced pressure.
It is possible to obtain a molded coil with improved stability, stable and uniform characteristics, and high reliability.

〔Example〕

Furthermore, an example of a method for manufacturing a magnetic resin molded coil according to the present invention will be explained in detail with reference to FIGS. 1 to 3.

In this example, the mold (11) has a cavity (12
) consists of a first mold (21) and a second mold (22) divided into two along a plane perpendicular to the central axis (axis 0-0 of the coil). On the other hand, the coil (2) is configured in advance into a cylindrical shape,
Along the axial direction from one end of the °C coil terminal lead (2
This is the case in which t+)(2tz) is derived.

In this case, both terminal leads (2t+) of the coil (2) are attached to the bottom of the cavity of one mold, for example, the second mold (22).
(2t,) to the outside through the lead outlet hole (14,
) and (14□) are provided, and the mold on the opposite side (
A runner (I5) for injecting magnetic resin into the runner (I5) and a plurality of gates (I5) communicating with the runner (I5) and opening into the cavity (12)
17) ((17c) (17s1)(17sz)”
This gate (17) is provided with, for example, one central gate 1117 facing the central hole (2h) of the coil (2) disposed in the cavity (12).
c), and a plurality of outer circumferential gates (17sυ (17s2) in the example shown in FIG. (17s
3) Consists of (17s4).

In the cavity (I2), coil positioning protrusions (13) are arranged that abut against the edges of the coil (2), for example, both edges. Gorera coil positioning protrusion (1
3), for example, the coil (
For example, four protrusions may be provided at equal angular intervals with respect to the axis 0-0 of 2). In addition, these protrusions (13) have a so-called R surface with a gently curved roundness at the edge that meets each coil (2) so that the insulation '#1 covering of the coil will not be peeled off. do.

Further, the gate (17) is connected to the coil (2) as described above.
each coil positioning protrusion (13) in the cavity (12).
) is placed at a predetermined position surrounded by L, and a central gate located at the center, that is, the first injection gate (17c), and a plurality of openings located at the outer periphery of the coil - L end. outer peripheral gate (second injection gate) (17s
υ(17s2)..., but in this case, the opening area Sc of the first injection gate (17c) and the opening area of the second injection gate (17s l) (17s z)... The ratio Sc/Ss of the sum to Ss is the volume Vc of the cavity in the center hole (2h) of the coil (2) and the coil (
2) Ratio to the volume Vs at the outer periphery (envelope) V e
/ Vs, for example, are selected to be approximately equal.

In this way, the mold (21) and the mold (22) are matched with each other with the coil (2) placed in a predetermined part in the cavity (12), and the mold is inserted into the cavity through the runner (15) and each gate (17). (12) Injection or injection molding of magnetic resin is performed inside. After that, when the molds (21) and (22) are separated and the molded body is taken out from inside the cavity (12), the coil (2) is embedded in the magnetic resin mold (1) as shown in Figure 3. A molded coil (30) is obtained.

The molded coil (30) obtained in this manner can be embedded concentrically within the magnetic resin mold (1) without substantially deforming the coil (2).

The magnetic resin has, for example, a resin content of 28 to 35% by volume, preferably less than 30% by volume, and an initial magnetic permeability of 200 to 1500 G (
Gauss) with a particle size in the range of several μm to several tens of μm, such as Mn-Zn ferrite, Nu-Zn ferrite, Mg-Zn ferrite, or metal magnetic powder, such as Sendust, Permal l:1 It can be formed by a magnetic resin containing 72 to 65% by volume, preferably 70% by volume or more of any one or more of the following. Here, the resin material includes polypropylene, polyamide, polyphenylene sulfide, polyethylene, polystyrene, and ethylene acetic acid. Vinyl copolymer, ethylene ethyl acrylate, 6-nylon, 6,6 nylon, 6,10-nylon, ll
- Thermoplastic resins such as nylon, 12-nylon, polyethylene terephthalate, polybutylene terephthalate, etc. can be used.

In the above example, the first injection gate (17
This is the case where one game h (17C,) (17c,,) is provided, although this is not shown.
In this case, the 1-1 area Vc between
These multiple gates (17cl) (17cz)...
・Between each [is the sum of 1 area.

Also, the second injection gate (17s+) (17sz)
. . ” is not limited to the above-mentioned four examples, but can include two or more.

Also, the length of the resin supply runner for the first injection gate and the second injection gate as required.

By selecting the thickness, etc., there is a difference in the starting point of resin injection into the center of the coil (2) and resin injection into the outer periphery, which allows for better adjustment of the pressure balance inside and outside the coil (2). It can also be done at a high level.

〔Effect of the invention〕

-L As mentioned above, in the method of the present invention, the coil (2)
In injection molding of the magnetic resin for the coil (2), the injection gate for the resin into the 4' cavity (12) of the mold (11) is placed in a first injection game) (17c), and a plurality of second injection gates (1
7s1), (17s-), (17S,)...
and the opening area ratio S c / S s is determined by the resin filling volume ratio Vc / of the center part and the outer peripheral part of the coil (2).
For example, by setting Sc/5s-Vc/Vs in correspondence to Vs, the amount of resin filled in the center (inside the center hole) of the coil (2) and the same amount of filled resin in the outer periphery become the respective volumes. Since the resin is filled uniformly at a predetermined ratio, the coil (2) is filled with resin from the periphery to the inside, or from the inside to the outer periphery. This means that the application of balanced pressure can be effectively avoided.Therefore, based on this pressure, the coil (2
) deformation and eccentricity can be avoided, and peeling of the insulation coating due to friction caused by unbalanced pressure between coil wire elements can also be avoided, improving yields, stabilizing and uniformizing characteristics, and molding coils with high reliability. can be obtained.

In addition, the first and second injection games I-(17c) ((1
7c, ) (17cz) --...) and (17s) (
(17sυ (17s2) ”...), and by measuring the balance of the injection resin inside and outside of ζ 1 ile (2) by its opening area, the injection pressure of injection molding, It becomes easier to set molding conditions such as mold temperature and resin temperature.

[Brief explanation of drawings]

FIG. 1 is a -L view of an example of a mold for carrying out the method of the present invention;
FIG. 2 is a sectional view taken along the line 8-A, FIG. 3 is a perspective view of the magnetic resin molded coil, and FIG. 4 is a sectional view of the molded coil used to explain the present invention. (1) is a magnetic resin mold, (2) is a coil, (11) is a mold, (17c) is a first injection gate, (17s+) (17sz)... is a second injection gate. Agent Hidemori Matsukuma 1st figure 2: Resistance to the figure 1 of the figure 2

Claims (1)

[Claims] In obtaining a magnetic resin molded coil in which a coil is embedded in a magnetic resin mold, a magnetic resin molded coil is provided opposite to the center of the coil arranged in the cavity of the mold. The magnetic resin is mainly fed into the coil from at least one first injection gate, and the magnetic resin is mainly sent into the outer periphery of the coil from a plurality of second injection gates provided opposite to the outer periphery of the coil. The resin is fed into the coil such that the ratio of the total opening area of the first injection gate to the cavity and the total opening area of the plurality of second injection gates to the cavity is approximately A method for manufacturing a magnetic resin molded coil, wherein selection is made in accordance with the ratio of the filling volume of magnetic resin inside the coil to the filling volume of magnetic resin at the outer periphery of the coil.