JP3379400B2 - Injection compression mold - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection compression molding die for pressurizing and compressing a resin injected into a cavity. Particularly, a gate and a molded product are formed by closing the gate with the die during molding. The present invention relates to an injection compression molding die to be separated.

[0002]

2. Description of the Related Art When the flow distance of molten resin injected into a cavity from a gate is not uniform, or when the thickness of the cavity changes in the resin flowing direction, the direction from the gate to the flowing resin or the tip is changed. Since the pressure gradient is not uniform and the resin density distribution in the cavity is non-uniform, there is a problem that the molded product shrinks and the quality deteriorates.

In order to avoid such a problem, molten resin is injected into a cavity formed thicker than the final molded product, and the volume of the cavity is reduced so that the injected resin is made uniform. An injection compression molding method of compressing under pressure has been conventionally adopted. According to this injection compression molding method, a large volume of the cavity can be secured when the molten resin flows, so that even if the flow distance is the same, the required injection pressure is small and the pressure gradient is small. can do. In addition, there is an advantage that the specific volume can be reduced and the molecular orientation can be made uniform by pressing and compressing the resin filled in the cavity.

By the way, in such an injection compression molding method, molten resin is injected and filled in a mold that has been clamped, and after cooling, the molded product is ejected by an ejector pin, whereby the runner gate and the molded product are separated. Although there is a gate cutting method for cutting and separating from the outer peripheral surface, this method is not preferable in terms of appearance because a gate mark is left on the cut portion because the resin is cut in a solidified state. As a countermeasure against this, conventionally, a gate cutting means for closing the gate filled with the resin by a mold that moves while compressing the resin at the time of mold clamping to separate the gate and the molded product before the resin solidifies, so-called An injection compression molding die that performs in-mold gate cutting is used.

[0005]

However, the above-mentioned injection compression molding die has the following problems. That is, when the mold is pushed quickly, the molten resin cannot escape, the resin pressure in the cavity increases, and it becomes impossible to push the mold sufficiently until it reaches a predetermined thickness. On the contrary, if the die is pushed slowly, a solidified layer is formed on the die surface, and in this case also, the die cannot be pushed sufficiently to a predetermined thickness. Therefore, if it is difficult to adjust the pressing movement of the mold and the mold cannot be pressed sufficiently, the gate and the molded product may not be completely separated, which may result in defective gate cutting. It was Particularly, in the case of a thin molded product, the above-mentioned inconvenience is likely to occur because the space between the cavities becomes narrow.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an injection compression molding die capable of reducing the occurrence of gate cut defects and performing good compression molding.

[0007]

The present invention has the following features to attain the object mentioned above. That is, in the injection compression molding die according to claim 1, a fixed die, a movable die that is opened and closed with respect to the fixed die to form a cavity between the fixed die, and the movable die facing the cavity. An injection compression molding die that includes a pressing unit that presses the molten resin from the gate and then presses the movable mold toward the fixed mold by the pressing unit to compress and mold the molten resin. The fixed mold is provided with a fixed-side core mold that constitutes a part of the inner surface of the cavity and is arranged. The movable mold faces the fixed-side core mold and is fixed to the inner surface of the cavity. A movable core die is provided that constitutes a part of the movable core die and is movable in the opening / closing direction.One of the fixed core die and the movable core die serves as a gate when the die is clamped. In the closed state, the other mold is Die urging means for urging the opening and closing direction is provided, the
The mold urging means includes the fixed core mold and the movable core.
The mold and the molten resin in the cavity are compressed
When the mold is closed, the other mold maintains the pressure inside the cavity.
A technique is adopted that urges one side to move backward while holding it .

In this injection compression molding die, one of the fixed-side core die and the movable-side core die closes the gate when the die is clamped, and the other die has this gate die. die urging means for urging the opening and closing direction is provided, the gold
The mold urging means includes the fixed-side core mold and the movable-side core mold.
The molten resin in the cavity is compressed by the mold and the gate
When the mold is closed, the other mold maintains the pressure inside the cavity.
However, since it is urged so as to retract toward one side, when the movable side core mold is pressed and moved to the fixed side core mold side, the fixed side core mold or the movable side core mold facing each other The other mold moves backward with respect to the one mold while maintaining the cavity internal pressure by the urging force of the mold urging means, so that the one mold is sufficiently pushed into the cavity. Therefore, the gate is completely closed by the one mold sufficiently pushed into the cavity, and the gate and the molded product are completely separated.

The injection compression molding die according to claim 2 is the injection compression molding die according to claim 1, wherein the cavity is formed in a plate shape, and the gate is provided over the entire peripheral edge of the cavity. The technology arranged in a ring is adopted.

In this injection compression molding die, the cavity is formed in a plate shape, and the gate is arranged in an annular shape over the entire peripheral edge of the cavity. Therefore, compared with the case where the gate is arranged locally, The pressure distribution in the cavity is less likely to be biased, the molded product is less likely to be distorted, and a good gate cut can be obtained over the entire outer peripheral edge.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an injection compression molding die according to the present invention will be described below with reference to FIGS. In these drawings, reference numeral 1 denotes a fixed die, 2 a movable die, 3 a cavity, and 4 a pressing means.

The injection compression molding die of this embodiment is a die for injection compression molding an IC card. As shown in FIG. 1, the fixed die 1 and the fixed die 1 are opened and closed. Movable mold 2 that forms a cavity 3 between itself and fixed mold 1
And a pressing means 4 for pressing the movable die 2 toward the cavity 3. A fixed core mold 5 that constitutes a part of the inner surface of the cavity 3 and is movably arranged in the opening / closing direction is fixed to the fixed mold 1. The fixed core mold 5 is a gate 6 when the mold is clamped. Is set to a closed state.

The movable die 2 is fixed by a pressurizing means 4 to a receiving plate 7 movably arranged in the opening / closing direction. A core supporting plate 8 is fixed to the receiving plate 7 on the fixed die 1 side. There is. The core support plate 8 is provided with a movable core die 9 that faces the fixed core die 5 and constitutes a part of the inner surface of the cavity 3 and is movably arranged in the opening / closing direction.

A disc spring (mold urging means) 10 for urging the movable core mold 9 with a predetermined urging force in the opening and closing direction is different from the fixed core mold 5 in the movable core mold 9. A plurality of disc springs 10 are provided on the opposite side, and are housed in spring recesses 11 formed on the surface of the core support plate 8 facing the movable core die 9. In addition, the fixed-side core mold 5 and the movable-side core mold 9 each have a plurality of through holes 12 through which cooling water flows.

As shown in FIG. 2, the cavity 3 is an IC
It is formed into a rectangular plate shape corresponding to the shape of the card, and is connected to an injection molding machine (not shown) through the sprue 13, runner 14 and gate 6 so that the molten resin injected from the injection molding machine is filled. It is configured. The gate 6 is annularly arranged over the entire periphery of the cavity 3. In addition, the movable core die 9, the core support plate 8, and the receiving plate 7 are provided with ejection pins 15 that eject and eject the molded product in the mold open state so as to penetrate into the cavity 3 so as to project. .

Next, an injection compression molding method in the injection compression molding die of this embodiment will be described with reference to FIG.

First, a molten resin R is injected from an injection molding machine and, as shown in FIG. 3A, through a sprue 13, a runner 14 and a gate 6, a pressurizing means 4 clamps the mold at a low pressure. The molten resin R is filled in the cavity 3 in the above state. At this time, the molten resin R is filled from the entire outer peripheral edge by the annular gate 6. Further, at this time point, the movable core die 9 is biased toward the fixed core die 5 side by the disc spring 10, so that the movable core die 9 and the core support plate 8 are moved.
There is a gap t of a predetermined interval between and.

After that, the movable die 2 is pressed by the pressurizing means 4 at a high pressure toward the fixed die 1 side as shown in FIG. 3B, and the fixed side core die 5 passes through the gate 6. Move to position. At this time, the molten resin R in the cavity 3 is compressed by the movable side core mold 9 and the fixed side core mold 5, and a part of the molten resin R flows back to the gate 6 side until the gate 6 is closed. . In addition, the movable core die 9
While the internal pressure of the cavity 3 is maintained by the biasing force of the disc spring 10, the gap t between the core support plate 8 and the fixed side core mold 5 is retracted as a clearance allowance, thereby fixing the fixed side core mold 5. Are further pushed into the cavity 3.

Further, by moving the movable die 2 by pressing, as shown in FIG. 3 (c), the movable core die 9 retracted by the internal pressure of the cavity is brought into contact with the core support plate 8 and positioned. The fixed core mold 5 is sufficiently pushed into the cavity 3. At this time, the gap between the fixed-side core mold 5 and the movable-side core mold 9, that is, the thickness of the cavity 3 is set to be the thickness of the molded product, and the gate 6 is fixed to the fixed-side core mold 5. Is set so as to be completely closed by, and the molded product and the gate 6 are completely separated.

After cooling, the mold is opened, and the molded product is ejected by the ejector pin 15 and taken out from the movable core die 9.

In this injection compression molding die, as described above, the gate 6 is completely closed by the stationary core die 5 sufficiently pushed into the cavity 3 to completely close the gate 6 and the molded product. In addition, since the fixed-side core mold 5 can be sufficiently pushed into the cavity 3 even if the space between the cavities 3 is narrow, the resin density distribution is uniform even in a thinner molded product. Good compression molding is possible.

Further, since the gate 6 is annularly arranged over the entire peripheral edge of the plate-shaped cavity 3, the pressure distribution in the cavity 3 is less likely to be biased as compared with the case where the gate is locally arranged. In addition, distortion is unlikely to occur in the molded product, and a good gate cut can be obtained over the entire outer peripheral edge.

In the above embodiment, the disc spring 10 is used to urge the movable core die 9 in the opening / closing direction, but other urging means may be used.

[0024]

The present invention has the following effects. (1) According to the injection compression molding die of claim 1, one of the fixed-side core die and the movable-side core die closes the gate when the die is clamped, and the other die. Is provided with a die urging means for urging the die in the opening / closing direction, and the die urging means is provided with the fixed core die and the flexible core die.
Molten resin in the cavity is compressed by the moving side core mold
And the gate is closed, the other mold will
Energize so as to move backward while maintaining the internal pressure
Since that, by retracting for one while maintaining the cavity pressure by the urging force of the other mold die biasing means, the gate by one of the mold is completely closed, the gate and the molded article And can be completely separated. Therefore, even if the gap between the cavities is small, it is possible to sufficiently push one mold into the cavity even if the gap between the cavities is narrow, so that even if the molded product is thinner, good compression molding without gate marks is performed. be able to.

(2) According to the injection compression molding die of the second aspect, since the cavity is formed in a plate shape and the gate is arranged in an annular shape over the entire peripheral edge of the cavity, the pressure inside the cavity is reduced. The distribution is unlikely to be biased, distortion is unlikely to occur in the molded product, and good gate cutting can be performed over the entire outer peripheral edge.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of an injection compression molding die according to the present invention.

FIG. 2 is a cross-sectional view of essential parts showing a cavity and a gate in one embodiment of the injection compression molding die according to the present invention.

FIG. 3 is a cross-sectional view of a main part for explaining an injection compression molding method in an embodiment of the injection compression molding die according to the present invention.

[Explanation of symbols]

1 fixed type 2 movable 3 cavities 4 Pressurizing means 5 Fixed side core mold 6 gates 9 Movable core mold 10 Disc spring (die urging means) R Molten resin

Continuation of the front page (56) Reference JP-A-8-216190 (JP, A) JP-A-9-29854 (JP, A) JP-A-8-323819 (JP, A) JP-A-9-1603 (JP , A) JP 5-116194 (JP, A) JP 2-86418 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B29C 45/26-45/38 B29C 33/00-33/76

Claims (2)

(57) [Claims] 1. A fixed die, a movable die which is opened and closed with respect to the fixed die to form a cavity between the fixed die, and a pressurizing means for pressing the movable die toward the cavity, An injection compression molding die for injecting a molten resin from a gate into a cavity and thereafter pressingly moving the movable die to the fixed die side by a pressurizing means to perform compression molding of the molten resin, wherein the fixed die has a cavity. A fixed-side core mold that is arranged to constitute a part of the inner surface of the cavity is provided, and the movable mold faces the fixed-side core mold and constitutes a part of the inner surface of the cavity and moves in the opening / closing direction. A movable-side core mold that is arranged so as to be possible is provided, and either one of the fixed-side core mold and the movable-side core mold has a gate closed when the mold is clamped, and the other mold is Is the mold bias that biases this mold in the opening and closing direction. Stage is provided, said mold biasing means, the movable-side co and the fixed side core mold
A mold and the molten resin in the cavity are compressed
When the seat is closed, the other mold will
An injection compression molding die characterized by urging so as to retract toward one side while maintaining . 2. The injection compression molding die according to claim 1, wherein the cavity is formed in a plate shape, and the gate is annularly arranged over the entire peripheral edge of the cavity. Injection compression mold.