JPH09277303A - Method for molding insert molding and its molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cancel the effects of molding shrinkage and to reduce the warpage of an insert by a method in which a warpage correcting synthetic resin is laminated on the side for correcting the warpage of the insert. SOLUTION: A metal plate 17a As an insert is inserted into the bottom surface of a lower shell 3a, and a synthetic resin 21 is injected into a cavity to be molded integrally. Next, on the outer side of the lower shell of the plate 17a, a cavity for the second shot surrounded by the outside surface of the plate 17a, the resin 21 of an primary side resin, and a moving mold core is formed. After that, a warpage correcting transparent synthetic resin layer 22 as a secondary side resin is injection-molded on the outer surface of the inserted plate 17a. In this way, the lower shell 3a in which the resin layer 22 is two-layer- molded on the inserted plate 17a is formed. As a result, the inside warpage effect of the resin 21 and the outside warpage effect of the resin layer 22 are canceled by each other to control the warpage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an insert-molded product having a metal-made insert part and preventing the warp of the insert-molded product while maintaining the texture of the metal and the insert-molded product.

[0002]

2. Description of the Related Art Conventionally, when a synthetic resin insert molded product having a metal insert part is molded, the insert part is made visible so that the molded product has a feeling of weight and texture. In order to obtain a high-grade feeling, the insert part is exposed to the outside of the molded product.

For example, as a tape cassette equipped with this type of reel, there is one having a structure shown in FIG. That is, the tape cassette 1 is formed into a box shape as a whole by combining the separately formed upper shell 2 and lower shell 3. Two reels 5 and 6 around which the tape-shaped recording medium 4 is wound are rotatably housed inside.

The reels 5 and 6 are set on the lower shell 3 side, and the central portion thereof is lightly pressed by the predetermined leaf springs 7 and 8 from the upper shell 2 side. The reels 5 and 6 set in this way are locked so as not to rotate when not in use by the reel lock portion 10 having a pair of claw portions incorporated in the reel lock mechanism 9 provided on the lower shell 3 side. There is. The reel lock portion 10 is biased in the reel direction by an elastic material 11 such as a coil spring.

Further, on the front side of the tape cassette 1, a back lid 12 and a front lid 13 for maintaining the tape-shaped recording medium 4 in an appropriate state are arranged,
The front lid 13 is openable and closable, and is always urged by a spring 13a in a closing direction.

The lower shell 3 has reels 5, 6 stored therein.
Holes 14 and 15 for driving the tape are provided, and a detection member 16 and the like for determining whether the tape is recordable or not are provided.

In such a tape cassette 1, since the lower shell 3 in particular has the driving holes 14 and 15, the strength against twisting or bending is weakened, and in order to reinforce this, It has been proposed to insert a metal flat plate having rigidity such as aluminum so as to cross the substantially central portion. This is also a tape cassette 1
It also aims to give a metallic feel to the product to give it a luxurious feel.

As shown in FIGS. 7 to 8, the insert of the metal flat plate 17 is set in the cavity 19 of the mold 18 at the time of molding the lower shell 3, and the synthetic resin is injection-molded in the cavity 19. Then, it is performed by integrally forming.

The metal flat plate 17 has holes 14 and 15 for driving.
Are provided in advance so that the synthetic resin does not enter into the holes 14 and 15 even if they are set in the cavity 19. The gate of the injection-molded synthetic resin, that is, the gate 20, is 3
At a certain point, molten synthetic resin is injected from each gate 20, synthetic resin portions 21 are integrally formed in front of and behind the metal flat plate 17, and the lower shell 3 is molded.

[0010]

In the lower shell 3 molded in this way, as shown in FIG.
7 and the synthetic resin portion 21 are integrally molded, but the synthetic resin has a phenomenon of molding shrinkage, and has a property of shrinking between injection and cooling and solidification.

Therefore, after molding, the synthetic resin portion 21
Shrinks over the entire area, but the metal flat plate 17 hardly shrinks, so that the shrinkage force of the synthetic resin portion 21 causes
Acts in the direction of compression (center direction).

As a result, as shown in FIG. 10, the metal flat plate 17 is deformed so that the entire lower shell 3 is warped and bulged outward.

When the lower shell 3 is deformed in this way, not only cannot the reels 5 and 6 housed inside be properly maintained, but also when the tape cassette 1 is used, a tape recorder, a video camera, or the like can be used. recording·
This causes inconvenience in setting the recording or reproducing device.

Therefore, although there is a proposal to insert a metal flat plate into a part of the tape cassette to give rigidity and to obtain a metal texture and a feeling of weight, substantially the difference between the properties of metal and synthetic resin is provided. As a result, the metal flat plate is deformed and warped after injection molding, and therefore there is a problem that must be solved to prevent the deformation.

[0015]

Means for solving the above problems of the method for molding an insert-molded article according to the present invention are as follows:
This is a method of molding by inserting an insert part in a part of the synthetic resin part, and forming a two-layer molding by laminating a warp straightening synthetic resin layer on the side of the insert part which corrects the warp.

The gist of the insert-molded product according to the present invention is as follows:
The warp straightening synthetic resin layer is made of a transparent synthetic resin material, and the insert part is made of metal.

According to the insert-molded product and the molding method thereof according to the present invention, the insert parts are molded so as to cancel out the contracting actions of the synthetic resin acting on the insert parts, so that the warp of the insert parts is reduced.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of an insert-molded product and a molding method according to the present invention will be described in detail with reference to the drawings. For ease of understanding, the parts corresponding to the conventional example will be described with the same reference numerals as the conventional example.

The first embodiment of the method for molding an insert-molded product according to the present invention is, as shown in FIG.
This is performed when the lower shell 3a of a is molded.

As shown in FIGS. 1 and 2, the tape cassette 1a is formed in a box shape as a whole by combining the separately formed upper shell 2 and lower shell 3a. Two reels 5 and 6 around which the tape-shaped recording medium 4 is wound are rotatably housed inside.

The reels 5 and 6 are set on the lower shell 3a side, and the central portion thereof is lightly pressed by the predetermined leaf springs 7 and 8 from the upper shell 2 side. The reels 5 and 6 set in this way are locked so as not to rotate when not in use by the reel lock portion 10 having a pair of claw portions incorporated in the reel lock mechanism 9 provided on the lower shell 3a side. There is. The reel lock portion 10 is biased in the reel direction by an elastic material 11 such as a coil spring.

On the front side of the tape cassette 1a, a back lid 12 and a front lid 13 for maintaining the tape-shaped recording medium 4 in an appropriate state are provided.
The front lid 13 is openable and closable, and is always urged by a spring 13a in a closing direction.

The lower shell 3a has a reel 5 stored therein.
6 are provided with holes 14 and 15 for driving 6,
A detection member 16 and the like for discriminating whether the tape can be recorded is provided.

Further, as shown in FIG. 2, a metal flat plate 17a is formed as an insert part on a part of the bottom surface of the lower shell 3a.
It is inserted by layer molding.

In the insert molding method of the metal flat plate 17a, for example, the plate thickness is slightly less than half the plate thickness of the metal flat plate 17 in the conventional example. In order to prevent the molten opaque synthetic resin 21 from filling in the metal flat plate 17a which is thinner than the metal flat plate 17, for example, the fixed side mold has the same shape as the metal flat plate 17a. Equipped with a movable core that can fill the half-thickness.

When molding the lower shell 3a,
The metal flat plate 17a is set on the movable core that has entered the cavity 19. Driving holes 14 and 15 are provided in advance in the metal flat plate 17a so that the synthetic resin 21 does not enter into the holes 14 and 15 even if they are set in the cavity. The synthetic resin 21 is injection-molded from the primary gate into the cavity to be integrally formed.

After the first shot,
The movable core is retracted to form a second shot cavity surrounded by the outer surface of the metal flat plate 17a, the synthetic resin 21 of the primary resin and the movable core on the outside of the lower shell of the metal flat plate 17a.

Thereafter, in order to stack the transparent synthetic resin layer 22 as the secondary resin for warpage correction, the transparent transparent resin melted on the outer surface of the metal flat plate 17a (the outer surface side of the lower shell 3a as an intermediate molded product). The synthetic resin is injection molded from the secondary gate.

This two-layer molding method is not limited to the example of making the above-mentioned exclusive mold, but as a second embodiment of the present invention, once as an intermediate molding product consisting of the insert part of the synthetic resin 21 and the metal flat plate 17a. The lower shell may be taken out of the mold after injection molding, transferred to a secondary mold, and the transparent synthetic resin may be injection-molded as the warp-correcting synthetic resin layer 22.

Thus, as shown in FIG. 2, a transparent warp straightening synthetic resin layer 22 is formed on the inserted metal flat plate 17a.
To form a lower shell 3a. Here, considering the warpage of the flat metal plate 17a due to the influence of molding shrinkage of the lower shell 3, as shown in FIGS. 3 to 4, the lower shell 3a is naturally cooled after demolding, and the warp straightening synthetic resin layer is obtained. The portion 22 is molded and shrunk, but the metal flat plate 17a hardly shrinks due to its material.

Therefore, as shown in FIGS. 3 to 5, the metal flat plate 17a is pulled by the contracting synthetic resin layer 22 and bulges inside the lower shell 3a. On the other hand, as described in the conventional example in FIG. 10, the contraction of the synthetic resin 21 forming the peripheral side wall of the lower shell 3a causes the lower shell 3a to warp inward as a whole, so that the metal flat plate 17a becomes lower. It is acted on so as to bulge outside 3a.

Therefore, an inward warping action due to the molding shrinkage of the synthetic resin 21 in the lower shell 3a and an outward warping action due to the molding shrinkage of the synthetic resin layer 22 for warping correction are applied to the metal flat plate 17a. They act in mutually opposite directions to cancel each other out, and as a result, warpage of the metal flat plate 17a is suppressed, and even if warpage occurs, it becomes extremely small to a negligible extent.

Since the metal flat plate 17a is inserted in the tape cassette 1a itself, the rigidity of the tape cassette can be improved. Further, since the transparent synthetic resin layer 22 is laminated by two-layer molding on the outer side of the lower shell 3a so as to overlap with the metal flat plate 17a, it is possible to see the metal flat plate 17a from the outside through the transparent synthetic resin layer 22. In addition, a heavy metal texture can be obtained, and a high-grade feeling of the tape cassette 1a itself having the lower shell 3a can be produced.

[0034]

As described above, in the method of molding the insert-molded product according to the present invention, the warp-correcting synthetic resin layer is laminated on the warp-correcting side of the insert part to form two layers. The effects of molding shrinkage due to the synthetic resin are canceled out by each other, so that the warp of the insert part can be reduced, and the excellent effect that the molded product can be maintained at high quality is obtained.

Further, since the warp straightening synthetic resin layer is formed of a transparent synthetic resin material and the insert parts are made of metal, it is possible to obtain the metallic texture of the molded product, and also it is heavy and has a high quality. It has an excellent effect of maintaining the image of the product.

The insert-molded product according to the present invention is an insert-molded product having an insert part in a part of the synthetic resin part, and since the insert part is laminated with a warp straightening synthetic resin layer, It has an excellent effect that an insert-molded product that is not affected by resin molding shrinkage can be obtained.

[Brief description of drawings]

FIG. 1 is an overall exploded perspective view of a tape cassette having a lower shell according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a cross-sectional view of the lower shell according to the first embodiment of the present invention, which is formed by two-layer molding.

FIG. 4 is a cross-sectional view for explaining how the transparent synthetic resin in the two-layer molded portion of the lower shell according to the first embodiment of the present invention is molded and shrunk.

FIG. 5 is an explanatory diagram showing a state in which a warp occurs in a two-layer molded portion of the lower shell according to the first embodiment of the present invention.

FIG. 6 is an overall exploded perspective view of a tape cassette having a lower shell according to a conventional example.

FIG. 7 is a plan view of a lower shell molding die according to the conventional example.

FIG. 8 is a bottom view of a lower shell according to the conventional example.

FIG. 9 is a sectional view taken along line BB in FIG. 8;

FIG. 10 is an explanatory diagram showing deformation due to molding shrinkage of the lower shell according to the conventional example.

[Explanation of symbols]

1,1a Tape cassette, 2 Upper shell, 3,3a
Lower shell, 4 tape-shaped recording medium, 17 and 17a metal flat plate, 18 mold, 19 cavity, 20 gate, 21 opaque synthetic resin, 22 transparent synthetic resin layer.

Claims (5)

[Claims] 1. A method of molding by inserting an insert part in a part of a synthetic resin part, wherein a warp-correcting synthetic resin is laminated on a side of the insert part for correcting a warp to form two layers. The molding method for insert molded products, characterized by: 2. The method for molding an insert-molded article according to claim 1, wherein the warp straightening synthetic resin layer is formed of a transparent synthetic resin material, and the insert part is made of metal. 3. The method for molding an insert-molded product according to claim 1, wherein the warp-correcting synthetic resin layer is molded with a thickness greater than that of the insert part. 4. An insert molded product having an insert part in a part of a synthetic resin part, wherein a warp straightening synthetic resin layer is laminated on the insert part. 5. The insert molded article according to claim 4, wherein the warp straightening synthetic resin layer is a transparent body molded from a transparent synthetic resin material.