JP2853866B2 - Magnetic resin molding method - Google Patents

Description

The present invention relates to a method for molding a magnetic resin.

[Summary of the Invention]

According to the present invention, in a method of molding a magnetic resin, the magnetic resin is directly heated and fluidized by high-frequency electromagnetic induction heating to thereby simplify the molding apparatus and improve the work efficiency of the molding operation.

[Conventional technology]

As a usual resin molding method, an injection molding method is widely used. In this case, usually, a heating heater is wound around a cylinder, a manifold, or the like of a molding machine, and a heating unit is heated to heat the resin material storage unit or a component member of the resin passage by heating the heater, thereby heating the resin material. The method is taken. In other words, in this case, the heating of the resin material is not only due to the heat capacity of the cylinder or the manifold, but also due to heat conduction, so that the time required to raise the temperature to a predetermined temperature is long and the efficiency of the molding operation is low.

On the other hand, for example, the molding apparatus disclosed in JP-A-61-108522 and JP-A-61-197216 adopts a method of high-frequency induction heating of the resin passage itself,
In this case, although the responsiveness of heating and raising the temperature is considerably improved, the dependency of the heat capacity of the resin passage still exists.

[Problems to be solved by the invention]

An object of the present invention is to solve the problem of low molding efficiency, which requires a long time to raise the temperature in resin injection molding as described above, and to further improve labor saving.

That is, the present invention particularly relates to a method of molding a magnetic resin.

That is, for example, as shown in FIG. 2, in various coils including an inductance element, a magnetic resin mold (2) is applied so as to embed the coil (1) including the inside of the coil (1). As a result, the same magnetic effect as that obtained by arranging a magnetic core in the coil (1) is obtained, and an electronic component such as a magnetic resin molded coil is obtained so as to obtain a casing effect for protecting the coil and a magnetic shielding effect. It is conceivable to configure

The present invention is applied to this type of magnetic resin molding method.

[Means for solving the problem]

According to the present invention, in a magnetic resin molding method, a magnetic resin is directly heated by high-frequency electromagnetic induction heating to obtain a fluid state, that is, a magnetic resin is molded while being fluidized or kept in a fluid state.

[Action]

In the present invention, since the magnetic resin material itself is directly heated and melted by high-frequency electromagnetic induction heating, the resin is heated to a predetermined temperature in a short time regardless of the heat capacity and thermal conductivity of the molding machine. , Control can be performed, so that workability can be improved.

〔Example〕

FIG. 1 is a schematic sectional view of a main part of an example of an injection molding machine for carrying out the method of the present invention. (11) is, for example, a lower mold having a plurality of (only one is shown in the figure) cavities (12). Inside the cabidi (12), for example, the electronic component described in FIG. (1) is arranged. (1
3) is a through hole from which the lead (2) of the coil (1) is led out. (14) is the upper mold that closes the cavity (12)
The upper die (14) has a gate (15) for supplying a resin material into each cavity (12) and a resin passage (16) communicating therewith.
Gates that have wear due to repeated molding work (15)
It has a tip portion (17) that can be freely exchanged for exchanging. (18) shows a manifold having a resin passage (19) communicating with each resin passage (16). Then, high-frequency electromagnetic induction coils (20) and (21) are wound around the manifold (18) and the chip portion (17), respectively.
A resin supply unit is connected to the resin passage (19).

As for the molding material of the magnetic resin mold, for example, soft magnetic powder is mixed in the molding resin at a ratio of 60 to 75% by volume,
This soft magnetic powder has a configuration in which one or more of Ni-based ferrite and Mg-based ferrite and one or more of Mn-based ferrite and metal magnetic material are mixed at a volume ratio of 1: 1 to 9.5: 0.5. . Then, by selecting the mixing ratio between the Ni-based ferrite and the Mg-based ferrite and the Mn-based ferrite and the metallic magnetic material, the specific resistance ρ is several Ωcm to several hundred Ωcm.
Is selected. This ferrite magnetic resin is, for example, a ferrite raw material such as a Ni-Zn ferrite raw material,
Fe ₂ O ₃ , NiO, ZnO powder and Mn-Zn ferrite raw material Fe
Ferrite raw material of ₂ O ₃ , MnO, ZnO powder
Bake at 00 ° C. Then, the Mn system was 1200
For Ni-based, Ni-based firing is performed at 1000 ° C in air. Thereafter, this is pulverized to a particle diameter having an average value of several μm to one hundred and several tens μm, and this is kneaded with a resin, for example, PS (polystyrene), PPS (polyphenyl sulfide) or the like to obtain a resin mold pellet. Then, this is heated and melted in, for example, a resin material supply section (not shown) and fed into the resin passage (19) of the manifold (18).

The high-frequency electromagnetic induction oscillators of the high-frequency induction coils (20) and (21) of the injection molding machine are selected at several tens kHz to several hundreds kHz. In this way, the magnetic resin generates magnetic flux in the magnetic material itself in the passages (19) and (20) and the gate (15) and generates an eddy current due to the magnetic material, which generates heat due to Joule heat and hysteresis loss. Thereby, fluidization by heat melting or softening to a required temperature, for example, 150 to 300 ° C., or fluidization state is maintained.

The arrangement part of the coils (20) and (21) such as the manifold (18) having the gate (15), the chip part (17) constituting the resin passage (16), and the resin passage (19) and the constituent parts in the vicinity thereof are as follows. By using a non-magnetic material such as copper, aluminum, brass, and non-magnetic ceramic, magnetic flux, that is, eddy current is mainly generated only in the magnetic resin, thereby saving power.

In this way, a fluid state is obtained by high-frequency induction heating of the magnetic resin itself, the magnetic resin is injected into the cavity (12), and the magnetic resin molding of the electronic component, for example, the coil (1) is performed. The magnetic resin mold electronic component shown is obtained.

In the above example, the specific resistance ρ of the magnetic resin is from Ωcm to several tens of cm.
Although it was selected to be 0 Ωcm, for example,
0 ⁵ Ωcm~10 can be about ⁹ [Omega] cm, by increasing the oscillation frequency due to the coil in this case (20) and (21), so as to perform its heating allowed effectively resulting hysteresis loss can do.

〔The invention's effect〕

In the present invention, since the magnetic resin material itself is directly heated and fluidized by high-frequency electromagnetic induction heating, the predetermined time can be shortened in a short time irrespective of the heat capacity and thermal conductivity of the molding machine as compared with the heater heating. Since the temperature control such as heating, cooling, and the like of the resin can be promptly performed at the above temperature, it is possible to save energy, improve workability, and thus improve mass productivity.

Further, the influence of the heat capacity can be reduced as compared with the case where the resin passage of the molding machine is induction-heated. Further, when the resin passage is induction-heated, there is a restriction that the material of the member constituting the resin passage is made of a magnetic material, or the cross-sectional area is limited to such a degree that Joule heat is easily generated. According to this, such inconvenience can be avoided because of direct high-frequency induction heating of the magnetic resin material.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an example of a molding machine for performing a magnetic resin molding method according to the present invention, and FIG. 2 is a perspective side view of an example of a magnetic resin molded electronic component. Numeral (12) is a kibiti, (15) is a gate, (16) and (19) are resin passages, and (20) and (21) are high frequency electromagnetic induction heating coils.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-42823 (JP, A) JP-A-63-60505 (JP, A) JP-A-57-4748 (JP, A) 4606 (JP, A) JP-A-63-309408 (JP, A) JP-A-1-275113 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 45/00-45 / 84 B29C 33/00-33/76

Claims (1)

(57) [Claims] 1. A method of molding a magnetic resin, wherein the magnetic resin itself is directly heated and fluidized by high-frequency electromagnetic induction heating to mold the magnetic resin.