JPH10329183A - Die and method for injection compression molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a slide contact section between a movable mold main body and a core section, improve the quality of individual molded products, control the unevenness of the molded product shape and contribute to the reduction of the cost of a mold. SOLUTION: A deformable sheet-shaped core coating section 5 forming a cavity face Cm of a movable mold 2 being in contact with a front face 3f of a core section 2 on a compression direction Xp of the core section 3 is formed on a movable mold 4 positioned on the front of the compression direction Hp of the core section 3 in the movable mold 2 to constitute an injection compression molding die 1 and the like. Also resin is cast in a cavity C by using the injection compression molding die 1, and then moved forward from the position of moving back toward the core section 3 by a compression margin L to the compression position to compress the resin the cavity C.

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 having a movable die having a compression core in a movable die body, and an injection compression molding method using the die.

[0002]

2. Description of the Related Art Conventionally, before filling a mold cavity with a resin, a movable mold core portion is retracted by a compression allowance.
An injection compression molding method for compressing the filled resin by moving the core portion after filling the cavity with the resin is known. By the way, the movable mold used in this type of molding method has a core portion that moves in the front-rear direction on the movable mold body, so that a sliding portion is generated between the movable mold body and the core portion. For this reason, a high degree of accuracy is required for the shape of the sliding portion of the core portion and the movable mold body, which increases the cost of the mold.

On the other hand, an elastic compression mold capable of performing compression molding without using a moving core portion is also disclosed in Japanese Patent Laid-Open Publication No. Hei.
This is known from US Pat. In the mold disclosed in the publication, a portion constituting a mold cavity is formed so as to be elastically deformable, and at the time of molding, a molding material is injected into the mold cavity to elastically deform the mold cavity in an enlarging direction. At the same time, the elastic force of the mold is applied to the entire surface of the molding material in the cavity to solidify it, so that even if the thin part of the molded product solidifies, the elastic pressure is independent of the non-solidified part. And the shape of the molded article is corrected to the final shape corresponding to the cavity shape.

[0004]

However, the above-mentioned conventional elastic compression mold (compression molding method) has the following problems.

First, since the degree of compression depends on the elastic force of the mold itself, the variation in the internal pressure of the mold directly affects the shape of the molded product. Therefore, in the case of a molded product that requires a high degree of thickness accuracy at a position, such as a lens, although the absolute shape can be easily corrected to the final shape, the shape of each molded product in each molding cycle (Relative shape) tends to cause large variation.

Second, since the elastic force of the mold itself directly affects the shape of the molded product, it is not easy to design the thickness and shape of the mold for setting the elastic force of the cavity portion in the mold. From this aspect, the cost of the mold is likely to increase.

The present invention has been made to solve the problems existing in the prior art. In addition to eliminating the sliding contact between the movable mold body and the core, the present invention improves the quality of each molded product. Further, it is an object of the present invention to provide a mold for injection compression molding and an injection compression molding method capable of suppressing variation in the shape of a molded product and contributing to cost reduction of the mold.

[0008]

The injection compression molding dies 1, 1a, 1b according to the present invention are provided on a movable mold body 4 located forward of the core portion 3 in the compression direction Hp of the movable mold 2. And a deformable thin-plate-shaped core covering portion 5 that forms a cavity surface Cm of the movable mold 2 in close contact with the front surface 3f of the core portion 3 at the compression position Xp of the core portion 3. In this case, the core covering portion 5 may be formed to have a constant thickness, or may be formed so that the peripheral edge 5s side is gradually thicker than the center 5c side.

Further, the injection compression molding method according to the present invention comprises:
Using the injection compression molding dies 1, 1a, 1b described above,
After the cavity R is filled with the resin R, the resin L in the cavity C is compressed by advancing the core portion 3 from the position retracted by the compression allowance L to the compression position Xp. In this case, the core part 3 has the cavity C
May be retracted by the compression allowance L before the resin R is filled into the core C, or may be advanced to the compression position Xp before filling the cavity C with the resin R, and the core coating portion swelled by the resin R being filled. 5, the compression margin L may be retracted.

As a result, the core portion 3 and the cavity C are partitioned by the core coating portion 5 provided on the movable die body 4, so that a closed cavity C is formed regardless of the position of the core portion 3. Therefore, the resin R in the cavity C
In addition to eliminating molding defects such as burrs caused by leaking out, the sliding contact portion between the movable mold body 4 and the core portion 3 can be eliminated. On the other hand, at the time of molding, for example, in a state where the core portion 3 is retracted from the compression position Xp by the compression allowance L,
If the cavity C is filled with the resin R, and then the core 3 is moved to the compression position Xp, the resin R in the cavity C
Can be compressed. Therefore, the operation at this time is performed by the core unit 3
This is the same as the basic injection compression molding method in which the movable mold 2 is moved and compressed.
The position and shape of the cavity surface Cm are accurately regulated by the core portion 3 without being affected by the internal pressure of the mold.

[0011]

Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, a configuration of a mold 1 for injection compression molding according to the present embodiment and a mold clamping device for clamping the mold 1 will be described with reference to FIGS.

The injection compression molding die 1 comprises a fixed die 6 and a movable die 2 shown in FIG. The fixed mold 6 has a cavity surface Cc and a sprue portion Js. On the other hand, the movable die 2 includes a movable die body 4 and a compression core portion 3 that is movably mounted on the movable die body 4 in the front-rear direction.

The movable body 4 located forward of the core 3 in the compression direction Hp is provided with a core coating 5. The core covering portion 5 is formed in a thin plate shape having a certain thickness. As a result, the core covering portion 5 becomes deformable (expandable and contractable).
Can be done. And the core coating part 5 is the core part 3
At the compression position Xp (see FIG. 2), the surface of the core coating portion 5 which is in close contact with the front surface 3f of the core portion 3 and faces the cavity surface Cc forms the cavity surface Cm of the movable mold 2.
Therefore, the cavity C is constituted by the cavity surface Cm and the cavity surface Cc. Jr indicates a runner portion and a gate portion of the cavity C. The molded product formed by the cavity C of the embodiment is assumed to be a concave lens.

On the other hand, the core portion 3 is disposed movably in the front-rear direction with respect to the movable body 4, but the core portion 3 and the movable body 4
By providing a predetermined gap between them, the sliding contact portion is eliminated. As a result, galling or the like is avoided, and smooth operation is ensured. On the front surface 3f of the core part 3, a molded product-shaped surface is formed which is modeled on the shape of the molded product. Thereby, when the front surface 3f comes into close contact with the core coating portion 5, the cavity surface Cm of the core coating portion 5 is deformed into the shape of a molded product. In addition, 1
Reference numeral 1 denotes a stopper mechanism provided between the movable body 4 and the core 3. The movement range of the core 3 with respect to the movable body 4 is regulated by the stopper pin 12, and the core 3 is moved backward by the spring 13. Be energized.

Such a mold 1 is attached to a mold clamping device 30 shown in FIG. The mold clamping device 30 includes a fixed platen 32 fixed on a machine base 31 and a movable platen drive unit 33 installed to face the fixed platen 32. A movable platen 35 is movably mounted on the horizontal tie bars 34 of the book. This movable board 35
Are moved along the tie bars 34 by the movable plate drive unit 33. The fixed mold 6 is attached to the fixed board 32, and the movable body 4 of the movable mold 2 is attached to the movable board 35. In this case, the core unit 3 is moved by a core driving unit (not shown) built in the movable board 35. Note that 40
Denotes a heating cylinder in the injection device. The heating cylinder 40 has an injection nozzle 41 at the tip and a screw 42 inside.

Next, an injection compression molding method using the injection compression molding die 1 according to the present embodiment will be described with reference to FIGS.

First, as shown in FIG. 3, the mold 1 is clamped by pressing the movable mold 2 against the fixed mold 6. FIG.
Denotes a mold 1 clamped. In this case, the core part 3 corresponds to FIG.
As shown in the figure, the compression position Xp is compressed by the compression allowance L (see FIG. 2).
Has receded from.

Next, the resin R measured in advance is injected and filled into the cavity C from the injection nozzle 41. When filling,
Since the core portion 3 and the cavity C are partitioned by the core coating portion 5, molding defects such as burrs caused by leakage of the resin R in the cavity C to the outside are reliably eliminated, and molding quality is improved. .

When the filling is completed, as shown in FIG. 2, the core portion 3 is advanced to the compression position Xp, that is, the core portion 3 is moved forward by the compression allowance L in the compression direction Hp, and the resin R filled in the cavity C is filled. Compress. At this time, since the core covering portion 5 is pressed against the front surface 3f (molded product shape surface) of the core portion 3 that advances, the core covering portion 5 is deformed along the front surface 3f,
While forming the original cavity surface Cm, the resin R filled in the cavity C is compressed by the compression allowance L.

Thereafter, when the molded article in the cavity C is solidified, the movable mold 2 is retracted to open the mold, and the molded article is discharged from the mold 1 by a projection device (not shown). Further, the core portion 3 returns to the position retracted by the compression allowance L from the compression position Xp.

As described above, the operation of the mold 1 by the injection compression molding method according to the present embodiment is the same as the basic injection compression molding method in which the core portion 3 is moved and compressed. Therefore, the position and the shape of the cavity surface Cm of the movable mold 2 formed by the core covering portion 5 are accurately regulated by the core portion 3 without being affected by the internal pressure of the mold. Variation is suppressed. Further, it is not necessary to design the elastic force of the mold itself, the material, and the like.

On the other hand, FIGS. 4 to 6 show modified embodiments.
FIG. 4 shows an injection compression molding die 1a according to a modified embodiment. The mold 1a according to the modified example has a structure in which the thickness of the core coating portion 5 is not made constant and the peripheral edge 5s side is formed gradually thicker than the center 5c side, thereby increasing the overall strength of the core coating portion 5. It is. In addition, this modified embodiment is different from the cavity C in FIG.
And a core driving unit 5 for moving the core unit 3 is assumed that a disk having a certain thickness is assumed as a molded product formed by
This embodiment differs from the embodiment shown in FIG. 1 in that 0 is a hydraulic cylinder provided in the movable body 4. In addition, 5 m shown by a virtual line in FIG. 4 indicates a position of the core coating portion 5 that is deformed when the cavity C is filled with the resin. Other configurations can be basically implemented in the same manner as the embodiment shown in FIG. Therefore, in FIG. 4, the same parts as those in FIG.
The configuration is clarified, and the detailed description is omitted. Also, the injection compression molding method using the mold 1a of the modified embodiment can be basically performed in the same manner as the injection compression molding method using the mold 1 described above.

5 and 6 show an injection compression molding method according to a modified embodiment. The injection compression molding die 1b shown in FIGS. 5 and 6 assumes a disk having a constant thickness as in FIG. Other configurations of the mold 1b can be basically carried out in the same manner as the embodiment shown in FIG. Therefore, in FIGS. 5 and 6, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the configuration is clarified, and the detailed description is omitted.

In the injection compression molding method according to the modified embodiment, during the molding, before the cavity C is filled with the resin R,
The above-described view is that the core portion 3 is advanced to the compression position Xp (see FIG. 6), and the core portion 3 is retracted by the compression allowance L by the core coating portion 5 which swells due to the resin R being filled. 1 is different from the injection compression molding method using the mold 1 shown in FIG. FIG. 5 shows a state where the cavity C is filled with the resin R. When the filling is completed, as shown in FIG.
To the compression position Xp, that is, by moving the compression allowance L forward in the movement direction Hp to fill the cavity C with the resin R.
Perform compression on. Other molding methods can be basically performed in the same manner as the injection compression molding method using the mold 1 described above.

Although the embodiment has been described in detail, the present invention is not limited to such an embodiment, and the detailed configuration, shape, material, method, etc., do not depart from the gist of the present invention. Can be changed arbitrarily.

For example, the case where the core covering portion 5 is formed integrally with the movable mold body 4 is exemplified, but the core covering portion 5 is formed by attaching a separately formed body to the movable mold body 4. Is also good. Thereby, workability is enhanced, and a material different from that of the movable mold body 4 can be selected as a material for forming the core covering portion 5. In this case, as a material for forming the core covering portion 5, a material in consideration of the function of the core covering portion 5 is selected. Further, in the embodiment, the core covering portion 5 is
Although the case where it is provided is shown, it may be provided in the fixed mold 6. Therefore, the “movable type” and the “movable type main body” in the present invention
Is a relative concept, and when the fixed mold 6 of the embodiment is the “movable mold 2”, the movable mold 2 of the embodiment is the “fixed mold 6”.

[0028]

As described above, according to the injection compression molding die of the present invention, the movable mold main body located in front of the core in the compression direction is provided with the movable mold cavity in close contact with the front surface of the core at the compression position. The core is formed by providing a deformable thin plate-shaped core covering portion that forms a surface, and the injection compression molding method according to the present invention uses the same mold, and after filling the cavity with resin, the core portion is removed. Since the resin in the cavity is compressed by advancing from the position retracted by the compression allowance to the compression position, the following remarkable effects are achieved.

In the injection compression molding mold, since the core and the cavity are partitioned by the core coating, a closed cavity is formed regardless of the position of the core.
Therefore, molding defects such as burrs caused by leakage of the resin in the cavity to the outside are eliminated, and molding quality can be improved.

Since the sliding contact portion between the movable body and the core can be eliminated, it is possible to avoid galling or the like and to ensure smooth operation.

The operation at the time of molding is the same as the operation of the basic injection compression molding method in which the core portion is moved to perform compression. Therefore, the shape of the molded product to be molded is accurately regulated by the core portion without being influenced by the internal pressure of the mold, and the variation in the shape of each molded product can be suppressed.

Since the elastic force of the mold itself is not directly used, it is not necessary to design the elastic force of the mold, the material, and the like, which can contribute to the cost reduction of the mold.

[Brief description of the drawings]

FIG. 1 is a sectional plan view showing a state before a resin is filled in an injection compression molding mold according to an embodiment of the present invention;

FIG. 2 is a cross-sectional plan view showing a state of the injection compression molding die during compression.

FIG. 3 is a side view of a mold clamping device showing a state where the injection compression molding die is attached.

FIG. 4 is a cross-sectional plan view showing a state before filling a resin in an injection compression molding mold according to a modified example of the present invention;

FIG. 5 is a cross-sectional plan view showing a state in which a resin of an injection compression molding mold used in an injection compression molding method according to a modified embodiment of the present invention is filled.

FIG. 6 is a cross-sectional plan view showing a state of the mold during compression.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Injection compression molding die 1a Injection compression molding die 1b Injection compression molding die 2 Movable mold 3 Core part 3f Front surface 4 Movable mold main body 5 Core coating part 5c Center 5s Perimeter Hp Compression direction Xp Compression position Cm Cavity surface C Cavity R Resin L Compression allowance

Claims (6)

[Claims] 1. An injection compression molding die having a movable die having a compression core portion in a movable die body, wherein a movable die body located in front of the core portion in a compression direction is provided at a compression position of the core portion. A mold for injection compression molding, comprising a deformable thin plate-shaped core covering portion which forms a movable mold cavity surface in close contact with the front surface of the core portion. 2. The injection compression molding die according to claim 1, wherein said core coating portion is formed to have a constant thickness. 3. The injection compression molding die according to claim 1, wherein the core coating portion is formed so as to be gradually thicker on a peripheral side than on a center side. 4. A deformable thin plate which forms a movable cavity surface in close contact with a front surface of a core portion at a compression position of the core portion in a movable body located in front of a compression core portion in a compression direction. After the cavity is filled with resin using an injection compression molding die provided with a core-shaped core coating, the resin in the cavity is compressed by advancing the core from the position retracted by the compression allowance to the compression position. Injection compression molding method. 5. The injection compression molding method according to claim 4, wherein the core portion is retracted by a compression allowance before filling the cavity with the resin. 6. The method according to claim 4, wherein the core portion is advanced to a compression position before filling the cavity with the resin, and is retracted by a compression margin by the core covering portion swelled by the resin being filled. The injection compression molding method according to the above.