JPH06106564A - Encapsulation molding method and mold - Google Patents

Abstract

PURPOSE:To obtain a method performing encapsulation molding of an insertion matter such as coils superior in crack resistance, moisture resistance and an external appearance of the surface by making use of a thermosetting resin molding material and a mold for its method. CONSTITUTION:This is an encapsulation molding method wherein a thermosetting resin molding material 12 is cast to the outside of the side of a molded product through a mold part forming a protrusion 10, simultaneously with shutting of a gate port 11 of a mold 6 by a gate shutting pin 4, gate cutting is performed and pressure to be increased within a mold cavity 16 at the time of molding solidification is decompressed by pressing down a pressure control pin 17 to be inserted within the cavity 16 by being supported by a spring 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a mold for encapsulating and molding coils with a thermosetting resin molding material.

[0002]

2. Description of the Related Art Conventionally, in a method of encapsulating and molding a coil with a thermosetting resin molding material, a melt viscosity of an unsaturated polyester resin or an epoxy resin is used so as not to cause a problem such as disconnection or deformation of a coil winding. A thermosetting resin molding material having a low viscosity is selected. However, in the case of unsaturated polyester resin, there is a problem that internal cracks occur due to thermal expansion during curing. In addition, since the gate opening of the molded product obtained by gate cutting from the molded product with sprue or runner obtained by normal transfer molding or injection molding does not have a skin layer formed by molding and curing the molding material with a mold. However, there are problems such as inferior moisture resistance and appearance.

[0003]

Therefore, the present invention provides a method for encapsulating a thermosetting resin molding material capable of encapsulating an insert such as a coil having excellent crack resistance, moisture resistance and surface appearance at low pressure. It is to provide a molding die for that.

[0004]

The first aspect of the present invention made in view of the above problems is an encapsulation molding method.
In the encapsulation molding, a thermosetting resin molding material is injected from a mold part forming a convex portion on the outer side surface of the molded product, and after the gate is cut, the molded product in the mold cavity is depressurized. The second aspect of the present invention is a molding die, which features:
It has a pin that is pushed out of the mold cavity when a pressure higher than a predetermined value is applied inside the mold cavity of the encapsulation molding.

[0005]

[Function] The thermosetting resin molding material melted from the nozzle is formed on the side surface of the molded product from substantially one end to the other end. After the injection, the gate shut pin in the nozzle is advanced to close the nozzle opening at the tip of the nozzle and at the same time the gate of the mold is closed, so it is sufficient for the molding material injected from the gate and filling the mold cavity. It can be molded under various pressures and temperatures. In this method, the gate portion can be made large on the side surface of the molded product, so that the molding material can be injected at a lower pressure, and the molding material to be injected can be uniformly filled from the convex portion along the circumference. . As a result, it is possible to minimize the influence on the enclosed coil and the residual stress. Further, since the filling is performed in parallel with the coil winding, it is difficult to generate a void near the winding.

Since the gate cutting is performed, it is not necessary to perform the gate cutting after the molding, and the appearance of the gate cut portion of the molded product can be made into a molded product having a beautiful skin layer finished with a mold like other parts. Therefore, it is possible to prevent moisture absorption from the gate port, and it is possible to obtain a molded product having excellent moisture resistance and excellent appearance of the molded product.

The convex portion formed on the outside of the side surface of the molded product forms a rib of the molded product, and the pressure adjusting pin supported by the spring is inserted into the rib from the end face opposite to the gate port of the rib. When a predetermined pressure or more is generated in the mold cavity, the pressure adjusting pin can be pushed down to release the pressure in the mold cavity. As a result, it is possible to prevent cracks from being generated in the molded product due to the pressure remaining inside the molded product after the molded product is obtained. Further, the convex portion formed on the side surface can also be used as a protrusion when the molded product is incorporated into the apparatus.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. The present invention is not limited to these examples.

FIG. 1 is a sectional view of a molding apparatus used in a method of molding a thermosetting resin molding material showing an embodiment of the first invention, in which a coil wound on a bobbin is set in a mold. This is a transfer molding device for performing encapsulation molding and showing a state in which the gate shut pin shuts the gate opening of the mold.

The transfer molding apparatus comprises a supply portion 1 for a cylindrical pot 9 having an up and down plunger therein, a manifold 2 connected to the pot 9 for temperature control, and a tip end of the manifold 2. A nozzle 3 having a gate shut pin 4 capable of opening and closing the opening 13 at the tip of the nozzle is provided in the attached nozzle 3, and the convex portion 10 protruding from the side surface of a substantially cylindrical molding die.
The molding material 12 melted by being brought into contact with the gate port 11 arranged on the upper surface of is injected into the mold 6. This convex portion 10
Is formed along the side surface of the substantially cylindrical shape to almost the lower end. A longer length is preferable because the injected molding material 12 can be uniformly injected along the circumference at a lower pressure. Further, when the convex portion farther from the convex portion closer to the gate opening 11 is thicker in thickness in filling the side surface in the circumferential direction, the molding portion closer to the gate opening 11 and the farther molding portion are more It is more preferable because it is uniformly filled.

2A and 2B and FIGS. 3A and 3B.
Is an enlarged cross-sectional view of a nozzle and a die part attached to the tip of a manifold connected to a supply part,
Each of (a) and (b) in FIG. 2 and FIG. 3 shows the operation sequence. By repeating this sequence, gate-cut transfer molding can be performed without a runner.

In the injection shown in FIG. 2 (a), the temperature at which the thermosetting resin molding material 12 melts is 40 to 120 ° C., preferably 6
The molding material 12 melted in the pot 9 heated to about 0 to 100 ° C. is transferred from the pot 9 to the manifold 2 and then to the flow path 5 of the nozzle 3 by the pressure of the plunger 8. The nozzle 3 is brought into contact with the gate opening 11 provided on the upper surface of the convex portion 10 on the side surface of the mold 6, and at the same time, the gate cut pin 4 in the nozzle 3 is pulled up to open the nozzle opening 13 to control the temperature. 2 and the thermosetting resin molding material 12 transferred through the flow path 5 in the nozzle 3 is injected into the mold 6. The flow path 5 also serves as a temporary retention site for the molten molding material 12 except during this injection. Therefore, the manifold 2 and the nozzle 3 have the molten molding material 12
30-110 in order not to change the viscosity of
The temperature is controlled by the temperature controller 14 to a temperature of ℃, preferably 35 to 80 ℃. Furthermore, the contact of the nozzle 3 with the mold 6 is only for an extremely short time of about 1 to 30 seconds of injecting the molding material,
A heat insulating portion 15 is provided at the tip of the nozzle 3, and the contact portion between the wall surface of the concave portion 7 of the die 6 into which the nozzle 3 is inserted and the outer surface of the nozzle is made as small as possible, and the heat capacity of the gate cut pin 4 is small. Due to such factors, the viscosity of the melted molding material 12 in the nozzle 3 hardly increases, and runnerless and gate cut continuous molding is possible.

The temperature of the manifold 2 and the nozzle 3 can be adjusted by, for example, a method of flowing a heat medium such as water, oil, or an organic solvent in the tubular temperature adjusting section 14, or an electric method such as an electric heater. The heat insulating part 15 may be made of an inorganic material, a material having bubbles, a resin material such as silicone, or the like which is usually used for a heat insulating plate.

In FIG. 2B, in the gate cutting, after the injection of the molding material 12 into the mold 6, the gate opening 11 of the mold 6 is closed by the gate cut pin 4 and the molding material 1 injected.
Prevent backflow of 2. With the gate cut pin 4, the encapsulating molding material that covers the insert can be sufficiently filled and pressed, and the appearance of the gate cut port 11 of the molded product has a beautiful skin layer similar to other parts that can be finished with a mold. A molded product having an excellent appearance can be obtained. In addition, since there is no part of the molded product that is lacking in the skin and easily absorbs moisture, the moisture resistance is improved.

In the curing of FIG. 3 (a), the gate opening 1 of the mold 6 is used.
Simultaneously with closing 6, the nozzle 3 is separated from the mold 6 to prevent the temperature rise of the nozzle 3. However, gate cut pin 4
Holds the gate opening 11 of the mold 6 closed until the injected molding material 12 is cured in the mold cavity 16. At this time, the pressure in the mold cavity 16 increases as the molded product tries to expand due to the heat of curing reaction. This increased pressure pushes down the support spring 18 of the pressure adjusting pin 17 inserted into the mold cavity 16 of the portion forming the rib of the convex portion 10 on the outside of the side surface of the molded product to depressurize the cavity 16. Become. The shape of the pressure adjusting pin 17, the location of the pressure adjusting pin, and the operating mechanism of the pin are not particularly limited, and a cylindrical rod shape is preferable in terms of processing. A shape memory alloy or the like can also be used.

3B, when the molding material 12 in the mold 6 is hardened and the molding material 12 does not flow back through the gate opening 11 of the mold 6, the gate cut pin 4 is moved to the mold. Separate from 6.

FIG. 4 is a perspective view showing an encapsulation molded product obtained by the mold of the second embodiment of the present invention, in which a solenoid coil is encapsulated with an unsaturated polyester resin molding material in a substantially cylindrical encapsulation. It is a molded product, and the convex portion 10 is formed on the side surface of the substantially cylindrical shape.
With ribs. A gate port 11 is provided on the upper surface of the rib of the convex portion 10, and a pin mark concave portion 19 into which a pressure adjusting pin for releasing pressure in the mold cavity generated at the time of molding and hardening is inserted is provided on the lower surface.

As the resin of the thermosetting resin molding material of the present invention, an unsaturated polyester resin, an epoxy resin, a phenol resin, a melamine resin, a urea resin, a silicone resin, an imide resin or the like may be used alone, and these may be used as a base resin. The modified resin described above and a combination resin of these resins can be used. Unsaturated polyester resin, epoxy resin, and silicone resin are preferable in that the melt viscosity is low,
The unsaturated polyester resin is preferable in terms of cost, and the epoxy resin is preferable in terms of performance such as electrical characteristics and mechanical characteristics.

The material of the pot, plunger, cylinder, screw, manifold, nozzle, gate shut pin, pressure adjusting pin of the supply unit is not particularly limited, and those normally used in these fields can be used as they are. You can

In the case where the supply unit has a molding material supply means of a transfer molding machine composed of a pot and a plunger, the thermosetting resin molding material can be charged each time or every several moldings, so that the molding material can be charged. Replacement and color change can be easily performed without material loss. In the case of injection molding in which the molding material supply means is composed of a cylinder and a screw, it is easy to continuously supply the thermosetting resin molding material, and therefore automatic continuous molding is easy.

[0021]

INDUSTRIAL APPLICABILITY According to the present invention, an insert using a thermosetting resin molding material can be encapsulated at low pressure, and an encapsulated product such as a coil having excellent crack resistance, moisture resistance and surface appearance can be obtained. Obtainable.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a transfer molding apparatus used in a molding method according to an embodiment of the first invention.

FIG. 2 is an enlarged cross-sectional view of a nozzle and a mold part showing an embodiment of the first present invention, and (a) and (b) show an operation sequence.

FIG. 3 is an enlarged cross-sectional view of a nozzle and a mold portion showing the first embodiment of the present invention, and (a) and (b) show an operation sequence.

FIG. 4 is a perspective view showing an encapsulated molded product obtained by a mold of one embodiment of the second present invention.

[Explanation of Codes] 1 Supply Unit 2 Manifold 3 Nozzle 4 Gate Shut Pin 5 Channel 6 Mold 7 Recess 8 Plunger 9 Pot 10 Convex 11 Gate Port 12 Molding Material 13 Cylinder 14 Temperature Control 15 Heat Insulation 16 Cavity 17 Pressure Adjustment pin 18 Spring 19 Pin mark Recess

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B29L 31:34 4F

Claims (4)

[Claims] 1. In the encapsulation molding, a thermosetting resin molding material is injected from a mold portion forming a convex portion on the outer side surface of the molded product, and after the gate is cut, the molded product in the mold cavity is depressurized. An encapsulation molding method characterized by the above. 2. The encapsulation molding method according to claim 1, wherein the thermosetting resin molding material according to claim 1 is an unsaturated polyester resin molding material. 3. A molding die which has a pressure adjusting pin which is pushed out of the mold cavity when a predetermined pressure or more is applied inside the mold cavity of the encapsulation molding. 4. The molding die according to claim 3, wherein the molding die is a molding die for encapsulating and molding coils using an unsaturated polyester resin molding material.