JPH0929798A - Injection compression mold and injection compression molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a gate cutting after molding. SOLUTION: A stationary side mold 1 is slidably engaged with a movable side mold 4, and a cavity 20 is formed before they are completely closed. A gate 23 formed of the mold 1 and a runner block 8 is formed at the position opened with the cavity 20 in the state before the molds 1 and 4 are completely closed and shielded by compressing the cavity 20 by completely closing the molds 1 and 4.

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 and an injection compression molding method which are often used for molding a thin molded product.

[0002]

2. Description of the Related Art In the injection compression molding method, resin is injected into a cavity with a mold opened by a predetermined amount, and after the filling is completed, the mold is closed and the resin is pressurized by the compression force. Is a method of molding. Therefore, as a mold used for injection compression molding, there is used a mold that has a socket-shaped dividing surface and in which a closed portion including a cavity is formed before the mold is completely closed.

As described above, the injection compression molding method has the advantages that the injection pressure is low because the resin is pressed by the compression force of the mold, and the excessive residual stress in the gate portion is prevented.
This is a molding method often employed in the molding of ultra-thin molded products such as optical parts and IC cards.

For example, as an example of a method for molding an IC card base material, Japanese Unexamined Patent Publication No. 6-285928 discloses an overall shape of an IC card base material formed on a movable die 104 as shown in FIG. A sliding block 115 having a shape corresponding to the fixed block 101 and the sliding block 1 is arranged.
15, a molding method using a mold for forming the cavity 120 and the gate 123 is disclosed.

To mold an IC card substrate using the above mold, first, the fixed mold 101 and the movable mold 104 are closed and the sliding block 115 is retracted. Then, an amount of molten resin required for molding is injected from the injection molding machine (not shown) through the sprue 121 into the cavity 120.

During the injection of the molten resin, or after the injection, before the molten resin solidifies, the hydraulic cylinder 116 is driven to advance the sliding block 115 as shown in FIG. As a result, the thickness of the cavity 120 is reduced, the cavity 120 is filled with the molten resin, and the molten resin is pressed by the compressive force of the sliding block 115. After the molten resin is cooled and solidified, the mold is opened and the molded IC card substrate is taken out. The molded IC card substrate is
Since the resin solidified by the gate 123 and the sprue 121 is integrated, the gate portion is cut after taking out the molded IC card base material.

The above-mentioned molding method does not apply a compressive force to the molten resin by the movement of the movable mold 104, but it is a kind of injection compression molding in that the thickness of the cavity 120 is reduced and the compressive force is applied. .

[0008]

However, in the above-mentioned conventional injection compression molding method, since the gate part is integrated in the molded product taken out from the mold, the gate cut of the molded product taken out from the mold is performed. A processing step is required.
The molded product taken out from the mold was already solidified, and the cut surface of the solidified resin was not clean and the appearance was unfavorable.

Therefore, an object of the present invention is to provide an injection compression molding die and an injection compression molding method which do not require a gate cutting process after molding.

[0010]

In order to achieve the above object, an injection compression molding die of the present invention comprises a pair of dies which are slidably fitted to each other, and the pair of dies are completely closed. In a mold for injection compression molding in which a cavity is formed in front and the cavity is compressed by completely closing the pair of molds, a gate that is an inlet of molten resin into the cavity has a pair of molds. Is opened to the cavity before being completely closed, and is formed at a position where the pair of molds are completely closed and the cavity is compressed to be blocked.

Further, one of the pair of molds is in contact with the other mold in a state where the cavity is formed, and the gate is formed between the mold and the other mold. The sliding member may be provided so as to be slidable with respect to the one mold while being in contact with the other mold as the molds are closed.

In this case, the sliding member may be biased toward the other mold by a biasing means, or the sliding member may completely close the pair of molds. The biasing force of the biasing means may be applied in the previous state.

The injection compression molding method of the present invention comprises a pair of molds that are slidably fitted to each other, and the gate, which is the inlet of the molten resin to the cavity, is in a state before the pair of molds are completely closed. Then, using an injection compression molding die formed in a position that opens in the cavity and is completely closed by the pair of dies and is blocked by the compression of the cavity, the pair of dies are completely The method is characterized in that after the molten resin is injected into the cavity before being closed, the pair of molds are completely closed to shut off the gate to solidify the molten resin before solidifying the molten resin.

[0014]

In the injection compression molding die of the present invention configured as described above, the molten resin is injected into the cavity before the die is completely closed, and the injected molten resin is solidified before solidification. Completely close and compress the cavity. Since the gate, which is the inlet of the molten resin into the cavity, is formed at a position where the gate is blocked by the compression of the cavity, the gate is blocked before the molten resin is solidified. That is, since the gate cutting process is performed by the compression of the cavity, a molded product having no gate mark is obtained.

In addition, a sliding member that comes into contact with the other mold in the state where the cavity is formed in one of the molds and forms a gate with the other mold is accompanied by a mold closing operation. By providing the mold so as to be slidable with respect to one mold while being in contact with the other mold, the gate and the resin passage accompanying it are formed on the divided surface of the mold. As a result, the resin solidified in the gate and the resin passage is exposed by opening the mold, and the resin can be easily taken out.

In this case, by biasing the sliding member toward the other mold by the biasing means, the sliding member is pressed by the other mold when the mold is completely closed. Retreat by. Therefore, there is no need for driving means or control means for moving the sliding member, and the structure of the mold is simple. In particular, by applying the urging force of the urging means while the mold is opened by the predetermined amount, the sealing property of the gate is improved, and leakage of the molten resin from the gate is prevented.

In the injection compression molding method of the present invention, first, the molten resin is injected into the cavity before the mold is completely closed, and then the mold is completely closed before the molten resin is solidified. At this time, as the mold, since the gate is the injection compression molding mold formed at the position where the gate is completely closed and the cavity is compressed, the injection compression molding mold is used. The gate is closed at the same time as it is closed. If the molten resin is cooled and solidified as it is, the resin in the cavity is separated from the resin in the gate and solidified, so that the gate cutting process after molding is unnecessary, and the process is simplified.

[0018]

Next, the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 is a sectional view of a first embodiment of an injection compression molding die of the present invention. As shown in FIG. 1, the mold of this embodiment is preferably used for molding a thin molded product such as a base material for an IC card. Cavity 2 in front
Main components are a fixed-side mold 1 and a movable-side mold 4 in which 0 is formed, and a runner block 8 as a sliding member provided on the movable-side mold 4.

The fixed-side mold 1 is attached to a fixed-side mounting plate 2 fixed to a fixed plate (not shown) of the injection molding machine. The fixed-side mold 1 is formed with a plurality of recesses 1a for forming a cavity 20 between the fixed-side mold 1 and the movable-side mold 4, and a groove serving as a gate 23 or a runner 22 communicating with each recess 1a. The depth D of the recess 1a is larger than the thickness of the molded product.

A sprue bush 3 is attached to the central portions of the fixed-side mounting plate 2 and the fixed-side mold 1 so as to pass through them. The sprue bush 3 has a sprue 21 having one end joined to a nozzle (not shown) of the injection molding machine and the other end communicating with the runner 22. Further, an ejector mechanism 10 for ejecting a molded product is provided for each recess 1a.

On the other hand, the movable mold 4 is attached to a movable plate side mounting plate 5 fixed to a movable plate (not shown) of the injection molding machine via a spacer block 6 and a receiving plate 7.

A stepped through hole 4a formed in the thickness direction of the movable mold 4 is opened in a region of the movable mold 4 which does not form the cavity 20. The outer shape of the runner block 8 matches the shape of the through hole 4a, and the runner block 8 is provided in the through hole 4a slidably in the thickness direction of the movable die 4. When the runner block 8 comes into contact with the fixed mold 1, the above-mentioned groove formed in the fixed mold 1 is closed by the contact surface of the runner block 8 with the fixed mold 1. The runner 22 and the gate 23 are constituted by. The contact surface between the runner block 8 and the fixed mold 1 constitutes a part of the dividing surface of the mold.

Further, on the end surface of the runner block 8 on the receiving plate 7 side, a flange portion 8a that abuts the stepped portion of the through hole 4a in order to regulate the amount of movement of the runner block 8 in the fixed side mold 1 direction. Are formed. At the position where the flange portion 8 a abuts on the stepped portion of the through hole 4 a of the movable die 4, the runner block 8 projects from the tip surface of the movable die 4. A compression coil spring 9 as a biasing means is provided between the runner block 8 and the receiving plate 7, and the runner block 8 is biased toward the fixed-side mold 1 by the spring force of the compression coil spring 9. Has been done. That is, in the mold open state, the runner block 8 projects from the tip surface of the movable mold 4.

As a result, the fixed mold 1 and the movable mold 4 are
1 and the state shown in FIG. 1, the runner block 8 comes into contact with the stationary mold 1 and the runner 22 and the gate 23 are brought into contact with each other, as shown in FIG. It is formed. Furthermore, by completely closing the fixed-side mold 1 and the movable-side mold 4, the movable-side mold 4 slides to compress the cavity 20, but the gate 23 does not allow the fixed-side mold 1 and the movable-side mold 4. The mold 4 and the mold 4 are completely closed, and the cavity 20 is compressed so as to be blocked.

At the end face of the runner block 8 on the stationary mold 1 side, which faces the sprue 21, a material pool 8b is formed.
Are formed. Ejector pin 1 for protruding runner
1 is provided so as to project from the material pool 8b.

In order to mold a molded product using the mold having the above construction, first, the movable side mounting plate 5 is moved forward to fit the movable side mold 4 and the fixed side mold 1 and the runner block 8 is fitted. Is brought into contact with the fixed side mold 1 to form a cavity 20 between the movable side mold 4 and the fixed side mold 1. At this time, the fixed-side mold 1 and the movable-side mold 4 are not completely closed, but only C is opened. Particularly in this embodiment, when the fixed side mold 1 and the movable side mold 4 are opened by C, the fixed side mold 1 presses the runner block 8 toward the movable side mold 4 side, and the compression coil spring 9 is slightly compressed. This allows
The spring force of the compression coil spring 9 acts on the runner block 8. At this time, the position of the tip end surface of the runner block 8 is preferably a position that does not recede with respect to the tip end surface of the movable die 4. This is to prevent the cross-sectional area of the gate 23 from becoming small and hindering the injection of the molten resin into the cavity 20.

Then, a molten resin in an amount necessary for molding is injected from the nozzle of the injection molding machine into the mold through the sprue bushing 3. Molten resin is sprue 21, runner 22
And is injected into the cavity 20 through the gate 23 in sequence. At this time, since the runner block 8 is pressed against the stationary mold 1 by the compression coil spring 9, the runner 2
2 and the gate 23 are improved in sealability, and leakage of the molten resin from the runner 22 and the gate 23 is prevented.

During or after the injection of the molten resin and before the molten resin is solidified, the movable side mold 4 is advanced to completely move the movable side mold 4 and the fixed side mold 1 as shown in FIG. Close to. At this time, the runner block 8 also tries to move forward, but since the runner block 8 is already in contact with the fixed-side mold 1, it cannot move any further, and the movement stroke of the runner block 8 moves to the compression coil spring 9. Be absorbed.
The cavity 20 is compressed by the forward movement of the movable-side mold 4 and becomes the thickness of the molded product. As a result, a compressive force is applied to the molten resin in the cavity 20, and the cavity 20 is filled with the molten resin.

Further, the gate 23 is automatically shut off by the end face of the movable side mold 4 at the same time as the movable side mold 4 advances. That is, although the gate cutting process is performed, since the gate cutting process is performed by the compression of the cavity 20, the trace of the gate 23 does not exist in the molded product. Further, the cavity 20 is compressed by completely closing the movable mold 4 and the fixed mold 1, but the positional relationship between the fixed mold 1 and the runner block 8 does not change, and the gate 23,
Since the volumes of the runner 22 and the sprue 21 do not change, the reverse flow of the molten resin does not occur.

After the molten resin is cooled and solidified, the movable side mold 4 is retracted to open the mold, and the ejector mechanism 10 causes the molded product in the cavity 20 to protrude from the fixed side mold 1. Since the molded product is separated from the gate 23 before being solidified, the gate cutting process after the molding is not necessary, and the process is simplified. Further, as described above, since the molded product has no gate mark, the appearance of the molded product is not impaired, and
In the case of a molded product whose surface needs to be decorated, the surface can be decorated well, which is particularly effective for molding a base material for an IC card.

On the other hand, since the runner 22 and the gate 23 are formed between the runner block 8 and the fixed-side die 1,
The resin in the sprue 21, the runner 22, and the gate 23 is exposed by opening the mold, and as the movable mold 4 moves,
It is pulled out from the fixed-side die 1 integrally with the runner block 8. The ejected resin is ejected from the runner block 8 by the ejector pin 11. Further, due to the die opening, the force applied to the runner block 8 is released, and the spring force of the compression coil spring 9 causes the tip end surface of the runner block 8 to return to the state of protruding from the movable side die 4.

(Second Embodiment) FIG. 4 is a sectional view of a second embodiment of the injection compression molding die of the present invention. The mold of this embodiment is an example in which the movable mold 54 and the fixed mold 51 have an inverse relationship to that of the first embodiment.

As shown in FIG. 4, a plurality of recesses 5 having a depth D'for forming a cavity 70 between the movable mold 54 and the fixed mold 51 are larger than the thickness of the molded product.
4a is formed, on the other hand, the runner block 58 is provided on the fixed side mold 51 so as to be slidable in the thickness direction of the fixed side mold 51. The runner block 58 is a fixed side mounting plate 52.
A compression coil spring 59 provided between and is biased toward the movable mold 54, and the tip of the runner block 58 projects from the fixed mold 51. Runner block 5
A gate 73 communicating with the cavity 70 is provided on the tip surface of
A groove to be the runner 72 is formed.

As a result, when the fixed side mold 51 and the movable side mold 54 are fitted together, the runner block 58 contacts the movable side mold 54 before the two are completely closed, and the movable side mold 54 is brought into contact. A runner 72 and a gate 73 are formed by 54 and the runner block 58, and a cavity 70 is formed by a portion surrounded by the fixed-side mold 51, the movable-side mold 54, and the runner block 58. Furthermore, the fixed side mold 51
By completely closing the movable mold 54 and the movable mold 54, the movable mold 54 slides to compress the cavity 70, while the gate 73 compresses the cavity 70 to fix the fixed mold 5.
It is formed at a position where it is blocked by 1.

A sprue 71 is formed at the center of the runner block 58, and the runner block 58 also serves as a sprue bush.

In order to mold a molded product using the mold having the above structure, first, the movable mold 54 is moved forward to move the movable mold 5.
4, the tip of the fixed-side mold 51 is fitted to the movable-side mold 5.
The cavity 70 is formed between the mold 4 and the fixed mold 51. At this time, the mold is not completely closed, but the runner block 58 is pressed by the movable mold 54 by the urging force of the compression coil spring 59, and the movable mold 54 and the runner block 58 make the gate 73 and the runner block. Forming 72.

Then, a nozzle (not shown) of the injection molding machine is used to inject the molten resin in an amount required for molding into the mold through the runner block 58. Molten resin is sprue 7
1, the runner 72 and the gate 73 are sequentially injected into the cavity 70. After injecting the molten resin and before the molten resin solidifies, the nozzle of the injection molding machine is connected to the runner block 5
8, the movable side mold 54 is moved forward, and the movable side mold 54 and the fixed side mold 51 are completely closed.

By completely closing the mold, the thickness of the cavity 70 becomes the thickness of the molded product, and a compressive force is applied to the molten resin in the cavity 70, so that the cavity 70 is filled with the molten resin. At the same time, the runner block 58
Due to the pressing force of the movable mold 54, the compression coil spring 59
It is pushed into the fixed side mold 51 against the biasing force.
As a result, the gate 73 is automatically shut off by the end surface of the fixed mold 51.

After the molten resin has been cooled and solidified, the movable side mold 54 is retracted to open the mold, and the molded product in the cavity 70 and the solidified resin in other parts are moved from the movable side mold 54 by the ejector mechanism. Stick out. Since the gate 73 is blocked before the resin is solidified, the molded product and the solidified resin in the other parts are separated from each other, and the gate cutting process after the molding is unnecessary.

[0041]

As described above, in the injection compression molding die of the present invention, the gate, which is the inlet of the molten resin into the cavity, is shut off during the compression process of the cavity, so that there is no gate mark. It is possible to obtain a molded product that is excellent in appearance and surface decoration.

Further, by providing a sliding member which is in contact with the other mold and constitutes a gate, in one of the molds, the resin solidified in the gate and the resin passage accompanying it can be easily removed from the mold. You can take it out.

In this case, by biasing the sliding member toward the other mold by the biasing means, there is no need for drive means or control means for moving the sliding member, and the structure of the mold is simple. Can be In particular, by applying the urging force of the urging means already in the state where the mold is opened by the predetermined amount, the sealing property of the gate is improved, and the leakage of the molten resin from the gate can be prevented.

In the injection compression molding method of the present invention, an injection compression molding die formed at a position where the gate is blocked by the compression of the cavity is used as the die, so that the gate is blocked simultaneously with the compression of the cavity. Thus, the resin in the cavity and the resin in the gate can be separated at the same time as molding. Therefore, the gate cutting process after molding is unnecessary, and the molding process can be simplified.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of an injection compression molding die of the present invention.

FIG. 2 is a sectional view taken along the line AA ′ of the injection compression molding die shown in FIG.

FIG. 3 is a cross-sectional view showing a state in which the mold is completely closed in the molding by the injection compression molding mold shown in FIG.

FIG. 4 is a sectional view of a second embodiment of the injection compression molding die of the present invention.

FIG. 5 is a sectional view of a main part of a conventional mold used for molding a thin-walled molded product.

6 is a cross-sectional view of an essential part showing a state in which a sliding block has been advanced in the molding using the mold shown in FIG.

[Explanation of symbols]

 1, 51 Fixed-side mold 1a, 54a Recessed part 2, 52 Fixed-side mounting plate 3 Sprue bushing 4, 54 Movable-side mold 4a Through hole 5 Movable-side mounting plate 6 Spacer block 7 Receiving plate 8, 58 Runner block 8a Flange part 8b Material pool 9,59 Compression coil spring 10 Ejector mechanism 11 Ejector pin 20,70 Cavity 21,71 Sprue 22,72 Runner 23,73 Gate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inoue Nakaji, total number 4102-142 Miyanodai, Miyadera, Iruma-shi, Saitama Japan Steel Works, Ltd. (72) Haruki Ota 1-5-1, Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. (72) Inventor Shigeru Uchida 2-664-8 Toyonodai, Otone, Kitasaitama-gun, Saitama Ikegami Mold Industry Co., Ltd.

Claims (5)

[Claims] 1. A pair of molds (1,
4, 51, 54), and the pair of molds (1, 4,
51, 54) are formed before the cavities (20, 70) are formed, and the pair of molds (1, 4,
In the injection compression molding mold in which the cavity (20, 70) is compressed by completely closing (51, 54), a gate (23, 73) which is an inlet of molten resin into the cavity (20, 70). However, the pair of molds (1, 4,
51, 54) is opened to the cavity (20, 70) before being completely closed, and the pair of molds (1, 70) is opened.
4, 51, 54) are completely closed and the cavity (2
0, 70) is formed at a position where it is blocked by being compressed. 2. The pair of molds (1, 4, 51, 54)
One of the molds (4, 51) contacts the other mold (1, 54) when the cavity (20, 70) is formed, and the other mold (1, 54)
The sliding member (8, 58) forming the gate (23, 73) between the pair of molds (1, 4, 51, 5) is
The mold according to claim 1, which is slidably provided with respect to the one mold (4, 51) while being in contact with the other mold (1, 54) with the mold closing operation of (4). Injection compression molding mold. 3. The injection according to claim 2, wherein the sliding member (8, 58) is urged toward the other mold (1, 54) by urging means (9, 59). Mold for compression molding. 4. The biasing means (9, 59) on the sliding member (8, 58) before the pair of molds (1, 4, 51, 54) are completely closed. The mold for injection compression molding according to claim 3, wherein the urging force is applied. 5. A pair of dies (1,
4, 51, 54) into the cavity (20, 7
The gate (23, 73), which is the molten resin inlet of 0),
In the state before the pair of molds (1, 4, 51, 54) is completely closed, the cavity (20, 70) is opened, and the pair of molds is completely closed to the cavity (20, 70). ) Is used to block the cavity (20) before the cavity (20) is completely closed by using a mold for injection compression molding formed at a position where it is blocked by being compressed. , 70) after injecting the molten resin into the pair of molds (1, 4, 5) before solidifying the molten resin.
1, 54) is completely closed to shut off the gates (23, 73) to solidify the molten resin.