JP2000061981A - Resin molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the positional dislocation of an object to be sealed which is to be inserted/molded into/in a resin from a specified sealing position. SOLUTION: A ferrite core 3 is installed in the recession part 4 of a core block 12 which constitutes a rein molding mold, an electromagnetic induction coil 2 and a resin sheet 9 are installed above the ferrite core 3, and a resin supplied from a sprue 7 is injected horizontally from a gate 8 into a resin packing space 11. The injected resin flows on the resin sheet 9 to be packed from the upper layer of the space 11, and the lower layer is filled by the melting of the resin sheet. Accordingly, the coil 2 is prevented from being raised from a prescribed position to be exposed from a resin molding and to be molded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molding method for forming a resin molded product by resin-sealing a structure at a predetermined position in the resin molded product.

[0002]

2. Description of the Related Art FIG. 6 is a sectional view showing an insert-molded product 1 formed in a bowl shape by resin-sealing an electromagnetic induction coil provided on the bottom surface of an electric rice cooker by electromagnetic induction heating.
An electromagnetic induction coil 2 and a ferrite core 3 are inserted in the insert molded product 1, and these are arranged in a resin filling space 11 formed in a bowl shape in a resin molding die as shown in FIG. Then, the resin filling space 11 is filled with the resin, and insert molding is performed.

FIGS. 7 and 8 show a state in which the electromagnetic induction coil 2 and the ferrite core 3 are insert-molded, and a section taken along the line C--A in which the ferrite core 3 shown in FIG. 4 is arranged, CB without ferrite core 3
The cross section of the line shows. A core block 12 and a cavity block 13 that form a molding part of a resin molding die.
In the resin filling space 11 formed between the sprue 7,
Resin is injected through the gate 8 to form the bowl-shaped insert molding 1 as shown in FIG. The ferrite cores 3 are formed in the shape of a square rod, and are arranged radially at four positions as shown in FIG. 4. In order to accommodate the ferrite cores 3 at predetermined positions on the core block 12, as shown in FIG. The position is fixed by a positioning member fixed to the bottom of the recess 4 formed radially. The positioning member is shown in FIG.
As shown in FIG. 3, the steel material 6 is provided with a magnet 5 at the lower portion, and the ferrite core 3 is attracted by the steel material 6 to be positioned and fixed. The electromagnetic induction coil 2 is arranged on the positioned ferrite core 3. The electromagnetic induction coil 2 is divided into an inner circumference coil 2a and an outer circumference coil 2b and wound, and is placed at a predetermined position on the core block 8 as shown in FIG. By closing the core block 12 on which the ferrite core 3 and the electromagnetic induction coil 2 are arranged by the cavity block 13, a sprue 7 and a gate 8 are provided in the resin filling space 11 formed as shown in the figure.
Resin is injected through to form an insert-molded product 1 as shown in FIG.

[0004]

When the resin supplied from the vertical direction is horizontally injected from the gate 8 to fill the resin filling space 11 with the resin as in the above resin molding method, the injected resin is It flows under the influence of gravity to the lower side, that is, the lower surface side of the resin filling space 11, that is, the core block 12.
The filling proceeds from the side first. In particular, since the recesses 4 are formed in the core block 12 at the positions where the ferrite cores 3 are arranged, the filling speed of the resin is higher than the other parts. FIG. 5A shows a cross section of the recess 4 in which the ferrite core 3 is arranged. The resin-filled space 11 a serving as the recess 4 is first filled with the resin, and the electromagnetic induction coil 2 The filling of the resin progresses into the resin filling space 11b on the upper surface side. That is, since the resin filling progresses from the lower layer side to the upper layer side of the resin filling space 11, the four concave portions 4 are formed.
In some cases, the filling of the resin that fills the gap and advances to the upper layer side lifts up the electromagnetic induction coil 2 whose position is not fixed, and the electromagnetic induction coil 2 is molded in a state of being exposed from the surface of the insert molded product 1. Further, since the ferrite core 3 is fixed in position on one end side of the rod shape, it is pushed up by the resin filled from the bottom of the recess 4 on the other end side,
Bending occurs at the other end side and the insert molded article 1 is sealed so as to be exposed on the surface.

The fluctuation of the sealing position of the electromagnetic induction coil 2 and the ferrite core 3 sealed in the insert molded product 1 is
The distance from the iron-made rice cooking pot accommodated in the insert-molded product 1 will vary, and the control of the rice cooking state by the control of electromagnetic induction heating will not be performed normally. In addition, the insulation of the electromagnetic induction coil 2 exposed on the inner surface of the insert-molded product 1 is not ensured. In order to prevent such a change in the sealing position due to the lifting of the electromagnetic induction coil 2, it is necessary to narrow down the molding conditions such as the filling speed, which causes a problem of lowering the production efficiency.

An object of the present invention is to provide a resin molding method in which the sealing position of the object to be insert-molded does not change.

[0007]

The first invention of the present application for achieving the above object is to provide a molded resin product by placing an object to be sealed at a predetermined position in the mold and filling the mold with resin. In a resin molding method in which an object to be sealed is sealed by injection molding, a resin sheet is placed on the object to be sealed arranged in the mold, and the resin sheet is filled with the resin sheet. It is characterized in that it is adjusted.

According to this resin molding method, since the flow of the resin filled by the resin sheet can be adjusted, when the object to be sealed is displaced from the predetermined position due to the flow of the resin, the resin sheet It is possible to change the flow of the resin to be filled so that the force to displace the object to be sealed does not act. Therefore, the molding conditions such as the filling speed of the resin can be relaxed and the production efficiency can be improved.

In the second invention of the present application, resin supplied from the vertical direction is horizontally ejected from a disk-shaped gate, and the resin is injected from the bottom of the bowl-shaped resin filling space toward the side peripheral wall. In a resin molding method of filling and sealing an object to be sealed arranged in the resin filling space with a resin to mold a bowl-shaped resin molded product, the resin sheet formed in a bowl shape is to be sealed. The upper layer of the resin-filled space is filled with the resin that is injected above the gate by causing the resin injected from the gate to flow over the resin sheet, and the resin sheet is melted and destroyed to cause the lower layer of the resin-filled space. It is characterized in that the resin is filled in.

According to this resin molding method, the resin injected horizontally from the gate by the resin sheet disposed on the object to be sealed flows on the resin sheet and is filled from the upper layer of the resin filling space first. Progresses. As the resin filling into the upper layer progresses, the resin sheet is melted by the heat of the flowing resin and the lower layer is also filled with the resin, so that the entire resin filling space is filled with the resin. By thus filling the resin from the upper side of the object to be sealed first, the object to be sealed is pressed downward, and a predetermined amount of the object to be sealed that occurs when the filling progresses from the lower layer first. Lifting from the position is prevented.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.
The embodiments described below are examples of embodying the present invention and do not limit the technical scope of the present invention.

In the resin molding method according to the present embodiment, the electromagnetic induction coil of the rice cooker using the electromagnetic induction heating is disposed at a predetermined position of the pot bottom of the rice cooker in a waterproof structure as in the prior art. Therefore, a resin molding method for forming an insert molded product in which the electromagnetic induction coil is resin-sealed is shown. The same elements as those of the conventional configuration are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 6, an insert-molded product 1 in which an electromagnetic induction coil (object to be sealed) 2 and a ferrite core (object to be sealed) 3 are resin-sealed in a predetermined position by a resin-molded portion 10. A resin molding method according to this embodiment for insert molding will be described below with reference to FIGS. 1 to 5.

First, the resin molding die is opened, and as shown in FIG. 4, the resin molding die is radially formed in the core block 12 constituting the molding part of the resin molding die as the resin filling space 11. The ferrite cores 3 are provided in the four recesses 4 respectively. As shown in FIG. 1, each ferrite core 3 has a magnet 5 attached to the bottom surface of each recess 4.
And a positioning member made of steel 6 adsorbs and fixes the position. Next, the electromagnetic induction coil 2 is attached to the core block 1
Place it on the specified position on 2. Further, a resin sheet 9 formed as shown in FIG. 3 is placed on the electromagnetic induction coil 2. The resin sheet 9 is formed by molding polypropylene resin into a thin circular sheet shape.

After disposing the ferrite core 3, the electromagnetic induction coil 2 and the resin sheet 9 on the core block 12 as described above, the mold is closed, and as shown in FIGS. A resin filling space 11 is formed between the cavity block 13 and the cavity block 13. 1 is a sectional view taken along the line C-A in FIG. 4, and FIG. 2 is a sectional view taken along the line C-B in FIG.

After the mold is closed, the resin is supplied from the sprue 7 provided in the vertical direction, and the resin is injected horizontally into the resin filling space 11 from the gate 8 formed in the disk shape. It flows on the upper surface of the resin sheet 9 and the filling proceeds from the upper layer of the resin filling space 11. As the resin filling progresses, the resin sheet 9 is melted and partially destroyed by the heat of the resin, and the resin is filled in the resin filling space 1 from the destroyed portion.
1 flows into the lower layer and is filled in the concave portion 4, and the resin sheet 9
As the resin melts and fuses into the resin, the resin filling space 1
All of 1 are filled with resin.

In this way, the resin is filled in the resin filling space 11
Since the electromagnetic induction coil 2 advances from the upper layer side, that is, from the upper surface side of the electromagnetic induction coil 2, the electromagnetic induction coil 2 is pressed onto the core block 12 and the resin sheet 9 is melted and then the recess 4 is filled with the resin. The coil 2 is resin-sealed in a state of being fixed at a predetermined position without rising from the predetermined position. This state can be presented more clearly by the diagrams shown in FIGS. 5A and 5B in comparison with the conventional method.

That is, in the conventional method shown in FIG. 5 (a), the filling of the resin is started from the concave portion 4 located below due to the influence of gravity, and the resin filling the resin filling space 11a of the concave portion 4 is filled with the electromagnetic induction coil 2. The filling is advanced so as to rise to the upper resin filling space 11b.

For this reason, the resin acts to lift up the electromagnetic induction coil 2, and the other end of the ferrite core 3 which is not fixed in position is lifted up to cause bending, and the electromagnetic induction coil 2 and the ferrite core 3 are cavities. Before the block 13 is brought into contact, it may be levitated.

On the other hand, in the method of the present embodiment, FIG.
As shown in FIG. 3, since the resin sheet 9 is provided, the resin is first filled in the resin filling space 11b above the electromagnetic induction coil 2, and the resin filling in the recess 4 is performed after the resin sheet 9 is melted. Since the space 11a is filled with the resin, the electromagnetic induction coil 2 is pressed against the core block 12 and is resin-sealed in a state in which the displacement does not occur due to lifting. Further, at the other end side where the ferrite core 3 is not fixed in position, the resin flowing on the resin sheet 9 flows from the cavity block 13 side to the core block 12 side, so that bending due to lifting on the other end side does not occur.

When the resin filled in the resin filling space 11 is solidified, the resin filling space 11 is filled with the electromagnetic induction coil 2
And the ferrite core 3 is replaced with the resin molding portion 10 which is sealed, and the mold is opened to resin-mold the insert molding 1 shown in FIG.

By forming the resin sheet 9 not to have a uniform thickness on the entire surface but to reduce the thickness of a predetermined portion,
Since the melting of the thin portion proceeds first, the resin filling space 11
In order to smoothly fill the resin in the predetermined portion of the above, it is possible to use the resin sheet 9 having a partially different thickness.

In the above embodiment, the resin molding method for sealing the electromagnetic induction coil 2 with the resin is described. When the object to be sealed is sealed in the resin by injection molding, the object to be sealed is injected into the mold. The same can be applied to the case where the sealing position moves due to the flow of the resin to be applied.

[0024]

As described above, according to the present invention, the flow of the injected resin can be changed by disposing the resin sheet to prevent the sealed object from moving from the predetermined position. Therefore, the object to be sealed can be accurately sealed at a predetermined position in the resin, and the object to be sealed is exposed on the surface of the resin molded product,
The occurrence of defects due to changes in the sealing position is prevented.

[Brief description of drawings]

FIG. 1 is a half sectional view of a ferrite core disposition position showing a configuration for carrying out a resin molding method according to an embodiment.

FIG. 2 is a 1/2 cross-sectional view showing a configuration for carrying out a resin molding method according to an embodiment.

FIG. 3A is a plan view showing the structure of a resin sheet,
(B) is a sectional view.

FIG. 4 is a plan view illustrating an arrangement of an electromagnetic induction coil and a ferrite core.

FIG. 5 is a transverse cross-sectional view for explaining resin filling by comparing the conventional configuration of (a) and the embodiment of (b) at the ferrite core arranging position.

FIG. 6 is a sectional view of an insert-molded product formed by a resin molding method.

FIG. 7 is a half sectional view of a ferrite core disposition position showing a configuration for performing a resin molding method according to a conventional technique.

FIG. 8 is a 1/2 cross-sectional view showing a configuration for carrying out a resin molding method according to a conventional technique.

[Explanation of symbols]

1 Insert molded product 2 Electromagnetic induction coil (object to be sealed) 3 Ferrite core (object to be sealed) 4 recess 7 sprue 8 gates 9 resin sheet 10 Resin molding part 11 Resin filling space 12 core blocks 13 Cavity block

Continued front page    (72) Inventor Yasuhito Miyake             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Kimio Yamashita             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Tomio Motomura             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Tatsuo Washizaki             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F term (reference) 4F202 AD03 AD05 AD08 AD18 AD35                       AG02 AG03 AG19 AG27 AH37                       AH51 CA11 CB01 CB17 CK07                       CK15 CK90 CQ03                 4F206 AD03 AD05 AD08 AD18 AD35                       AG02 AG03 AG19 AG27 AH37                       AH51 JA07 JB17 JB20 JL02                       JM04 JN11 JN25 JQ81

Claims (2)

[Claims] 1. A resin molding in which an object to be sealed is placed at a predetermined position in a mold, resin is filled in the mold, and injection molding is performed so that the object to be sealed is sealed in a resin molded product. In the method, a resin sheet is arranged on the object to be sealed arranged in the mold, and a resin filling state is adjusted by the resin sheet. 2. A resin which is supplied from a vertical direction is horizontally injected from a gate, the resin is filled from the bottom of the bowl-shaped resin filling space toward the side peripheral wall, and the resin is arranged in the resin filling space. In a resin molding method of molding a sealed object in a resin to mold a bowl-shaped resin molded article, a resin sheet is disposed on the sealed object, and the resin injected from the gate is A resin characterized in that the upper layer of the resin filling space is first filled with the resin by flowing the resin sheet, and the resin sheet is melted and destroyed so that the lower layer of the resin filling space is filled with the resin. Molding method.