JP3456017B2 - Disk cassette shell and mold device for molding the shell - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk cassette shell made of a synthetic resin by injection molding and a shell molding die device used for this injection molding.

[0002]

2. Description of the Related Art A disc cassette has a pair of joined shells, and the disc is rotatably accommodated in the pair of shells. 7 (a) and 7 (b) show inner views of the upper and lower shells 1 and 2, respectively. Figure 7
In (a) and (b), a disc exposure hole 3 is formed at a position where the shells 1 and 2 face each other, and the disc exposure hole 3 is opened and closed by a shutter. Further, a hub exposure hole 4 is formed at the center of the flat plate portion 2a of the lower shell 2,
The hub fixed to the center of the disk is exposed through the hub exposure hole 4. A circle is formed in the center of the flat plate portion 1a of the upper shell 1.
A circumferential rib 5 is provided so as to project, and the circumferential rib 5 regulates the position of the hub of the disk.

The pair of shells 1 and 2 are made of synthetic resin by injection molding. As shown in FIG. 8, the shell molding die device 6 includes a fixed mold 7 having a molding recess 7 a corresponding to the outer surface shape of the shell 1 or 2 and the shell 1 or 2.
And a movable side mold 8 having a molding convex portion 8a corresponding to the inner surface shape of the movable side mold 8, and the movable side mold 8 is bonded to the fixed side mold 7. At this bonding position, the molten synthetic resin is injected into the resin injection space formed by the molding concave portion 7a and the molding convex portion 8a. Then, after the molten synthetic resin is solidified, the movable mold 8 is set to a position separated from the fixed mold 7, and the shell 1 or 2 attached to the molding convex portion 8a of the movable mold 8.
Pull away.

At the time of releasing the shell 1 or 2 from the movable side die 8, a releasing resistance is applied to the shell 1 or 2, and the shell 1 or 2 is warped by the releasing resistance. Here, the lower shell 2 has a small release resistance because of its shape,
The amount of synthetic resin can be adjusted to cancel the warp. However, the upper shell 1 has a circumferential rib 5 at the center.
Since the circumferential rib 5 has a large release resistance, it is difficult to adjust the warp depending on the filling amount of the synthetic resin. Therefore, in the case of the upper shell 1, the mold temperature of the movable mold 8 is set to be about 10 degrees lower than that of the fixed mold 7, and the inner surface temperature is set lower than the outer surface temperature of the upper shell 1. It was prevented that the central portion of the inner surface as shown in FIG.

[0005]

However, if there is a large temperature difference between the fixed-side mold 7 and the movable-side mold 8, there is a vertical press-cut portion of the mold device 6 and a position in the expansion direction of the mold. Damage occurs, which will be described in detail below.

FIG. 10 (a) is an enlarged view of the portion A of FIG. 7, and FIG. 10 (b) is a partial cross-sectional view of the mold apparatus showing the molding state of this portion. In FIG. 10 (a),
A joining wall 9 is provided on the outer peripheral edge of the flat plate portion 1a, and a part of the joining wall 9 is configured to enter the inside of the U-shape. The U-shaped portion constitutes the cassette pull-in groove 10. In FIG. 10 (b), the fixed side mold 7 is provided with a molding recess 7a corresponding to the outer surface shape of the cassette pull-in groove 10 part, and the movable side mold 8 is provided with the inner surface of the cassette pull-in groove 10 part. A molding convex portion 8a corresponding to the shape is provided. The abutting surfaces 7b, 8b other than the molding concave portion 7a and the molding convex portion 8a are in close contact with each other, but the abutting surface itself is not in the same plane and has a step surface at one place. The molds 7 and 8 are configured as vertical pressing sections 7c and 8c. Therefore, if there is a difference in expansion due to temperature difference,
In the vertical push-cut portions 7c and 8c, since the expansion amount of the fixed-side mold 7 is large, the push-cut force becomes strong, which causes damage to the mold device 6, resulting in burrs on the molded product. It was

Therefore, the present invention provides a disk cassette shell capable of reducing the occurrence frequency of burrs due to damage to the mold as much as possible when producing a molded product without warpage, and a shell molding mold device used for the shell. The challenge is to provide.

[0008]

DISCLOSURE OF THE INVENTION A disk cassette shell according to the present invention for achieving the above object is a disk cassette in which a circumferential rib for restricting a position of a disk hub is provided at a center of an inner surface of a flat plate portion. in the shell, the respective inclination angles of the inner standing設面and outside elevational設面the circumferential rib, the inner standing
Set the tilt angle of the installation surface to a value greater than 3 degrees and within 10 degrees, and
Set the inclination angle of the standing surface to a value greater than 2 degrees and within 4 degrees.
This is a large setting with respect to the standing direction.

Further, the shell molding die device has a fixed side mold having a concave portion corresponding to the outer surface shape of the shell and a concave portion corresponding to the inner surface shape of the shell, which is detachable from the fixed side mold. A movable molding die having, wherein a shell molding mold device that forms a resin injection space by both concave portions in a state in which the movable mold is bonded to the fixed mold,
In the recess of the movable side mold, the corresponding groove inclination angles of the inner standing surface and the outer standing surface of the circumferential rib of the shell,
The corresponding groove inclination angle of the inner standing surface is greater than 3 degrees and within 10 degrees
To the value of, the corresponding groove inclination angle of the outer standing surface is larger than 2 degrees and 4
It is set to a value within a degree and is large in the drooping direction.

[0010]

[Function] Since the inclination angle between the inner standing surface and the outer standing surface of the circumferential rib is large and the corresponding groove inclination angle of the movable mold is also large, the draft of the circumferential rib is reduced. The larger
Mold release resistance decreases and the amount of convexity of the center of the inner surface of the shell of the molded product decreases, and as a result, warpage does not occur even if the temperature difference between the fixed side mold and the movable side mold is reduced. Is molded.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 show an embodiment of the present invention. FIG. 1A shows an inner view of the upper shell 1, and FIG.
1A and 1B are enlarged sectional views taken along line AA of FIG. 1 (a) and 1 (b), the difference in the configuration of the upper shell 1 compared with the above-mentioned conventional example is that the inclination angles θ ₁ of the inner standing surface 5a and the outer standing surface 5b of the circumferential rib 5 are different. , Θ ₂ only, and the respective inclination angles θ ₁ and θ ₂ are 3 and 2 degrees in the conventional case with respect to the standing direction m, but are set larger than this. Specifically, the inclination angle θ ₁ is set to a value greater than 3 degrees and within 10 degrees, and the inclination angle θ ₂ is set to a value greater than 2 degrees and within 4 degrees.

As shown in FIG. 2, the movable mold 8 used for molding the upper shell 1 also has corresponding groove inclination angles θ ₁ and θ ₂ corresponding to the above design changes. That is, the corresponding groove inclination angle θ
₁ and θ ₂ are set to the same values as above with respect to the drooping direction n.

In the above construction, the inclination angles θ ₁ and θ ₂ between the inner standing surface 5a and the outer standing surface 5b of the circumferential rib 5 are large, and corresponding grooves of the movable side mold 8 are correspondingly large. Since the inclination angles θ ₁ and θ ₂ are large, the draft of the circumferential rib 5 is large, so that the mold release resistance is small, and the amount of convex warp in the center of the inner surface of the upper shell 1 based on the mold release resistance is small. . As a result, in molding the upper shell 1 in which warpage does not occur, the temperature difference between the fixed-side mold 7 and the movable-side mold 8 may be reduced, and the occurrence frequency of burrs due to damage to the mold can be suppressed. .

Next, the inclination angle θ ₁ of the inner standing surface 5a is set to 10
The amount of warpage is compared between the case where the inclination angle θ ₂ of the outer standing surface 5b is set to 4 degrees and the case of the conventional example (the inclination angle θ ₁ is 3 degrees and the inclination angle θ ₂ is 2 degrees). Assuming that the points A and B shown in FIG. 3 are flatness measurement points, the (+) direction is the inward warp direction, and the (−) direction is the outward warp direction, as shown in FIG. The results shown in a) and (b) were obtained. That is, the upper shell 1 is an inner warp in the conventional example, but is an outer warp in the present embodiment, and from this measurement result, the fixed side mold 7 and the movable side mold 8 for canceling the warp at the time of molding are also formed. It can be seen that the temperature difference can be reduced.

The flatness is the value of the deviation of the measured object from the zero point of the reference plane plate of the dedicated measuring instrument.

Further, since the outer standing surface 5b is a surface with which the hub of the disk comes into contact, if the inclination is made too loose, the function of the product will be impaired, so that the limit is 4 degrees. Does not have the above restrictions. But,
When the inclination angle θ ₁ of the inner standing surface 5a is set to a value larger than 10 degrees, the dimension L at the base of the circumferential rib 5 becomes large as shown in FIG. The limit is 10 degrees. Therefore, the inclination angle θ ₁ (and the corresponding groove inclination groove) of the inner standing surface 5a is 10 degrees, and the outer standing surface 5b is
It is most preferable that the inclination angle θ ₂ (and the corresponding groove inclination groove) is 4 degrees.

In the embodiment, the fixed concave mold 7 is formed with the molding concave portion 7a and the movable movable mold 8 is formed with the molding convex portion 8a. However, the fixed concave mold 7 is formed with the molding concave portion 7a. The molding convex portions may be formed on the movable side mold 8.

[0018]

As described above, according to the present invention, the inclination angles of the inner standing surface and the outer standing surface of the circumferential rib of the shell are larger than 3 degrees. Within 10 degrees
The inclination angle of the outer standing surface is greater than 2 degrees and within 4 degrees.
The corresponding groove inclination angle of the movable mold corresponding to this value is set to a large value, and the corresponding groove on the inner standing surface is adjusted accordingly.
Inclination angle greater than 3 degrees and within 10 degrees
Corresponding groove inclination angle is set to a value greater than 2 degrees and within 4 degrees
Since it is set to a large value, it is possible to mold a shell that does not warp even if the temperature difference between the fixed side mold and the movable side mold is reduced, so the frequency of burrs due to damage to the mold can be reduced as much as possible. There is an effect.

[Brief description of drawings]

FIG. 1A is an inner view of an upper shell, and FIG. 1B is an enlarged cross-sectional view taken along line AA of FIG.

FIG. 2 is a partial cross-sectional view of a mold device (example).

FIG. 3 is an external view of an upper shell showing a measurement point (Example).

FIG. 4 is a side view of an upper shell showing a warp direction (example).

5A and 5B are characteristic line diagrams (examples) showing flatness states with respect to inclination angles.

FIG. 6 is a partially enlarged sectional view of an upper shell (example).

7A is an inside view of the upper shell, and FIG. 7B is an inside view of the lower shell (conventional example).

FIG. 8 is a schematic configuration diagram of a mold device (conventional example).

FIG. 9 is a cross-sectional view of an upper shell showing a warped state (conventional example).

10 (a) is a partially enlarged internal view of the upper shell, FIG. 10 (b).
FIG. 7A is a partially enlarged cross-sectional view of the mold device taken along line BB in FIG.

[Explanation of symbols]

1 ... Upper shell (shell) 1a ... Flat plate part 5 ... Circumferential rib 5a ... Inside standing surface 5b ... Outer standing surface 6 ... Mold device for shell molding 7 ... Fixed side mold 7a ... Molding recess 8 ... Movable mold 8a ... Molded convex portion

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G11B 23/03 604 G11B 23/113

Claims (2)

(57) [Claims] 1. A shell of a disc cassette, wherein a circumferential rib for restricting the position of a hub of the disc is provided at the center of the inner surface of the flat plate portion, the inclination of the inner standing surface and the outer standing surface of the circumferential rib. Angle, the angle of inclination of the inner standing surface is greater than 3 degrees
The inclination angle of the outer standing surface is larger than 2 degrees within 10 degrees.
A disc cassette shell characterized by being set to a value within 4 degrees to a large extent in the standing direction. 2. A fixed-side mold having a molding recess corresponding to the outer surface shape of the shell, and a movable-side mold detachable from the fixed-side mold and having a molding projection corresponding to the inner surface shape of the shell. In the shell molding die device, in which the movable side mold is bonded to the fixed side mold to form a resin injection space by the molding concave part and the molding convex part, the molding convex part of the movable side mold is provided. in the section, each corresponding groove inclination angle between the inner upright設面and outside elevational設面circumferential rib of the shell, inner standing
Set the corresponding groove inclination angle of the surface to a value greater than 3 degrees and within 10 degrees,
The corresponding groove inclination angle of the outer standing surface is greater than 2 degrees and within 4 degrees
The mold device for shell molding is characterized in that the respective values are set to be large in the hanging direction.