JPH07130130A - Metal mold for molding case for housing disk-shaped recording medium - Google Patents

Abstract

PURPOSE:To provide the metal mold for molding a case for housing a disk- shaped recording medium which does not generate warpage in a case constituting a disk cartridge. CONSTITUTION:A female mold 20 and a male mold 30 are arranged to face each other, by which a cavity C is formed. This female mold 20 has a gate G0 of a large injection port diameter and a circular conical projecting part 31 is formed in the part facing the injection port of the gate G0 on the inside surface 32 of the male mold 30. A molten resin is injected from the gate G of the large diameter if the molds are constituted in such a manner and, therefore, the molten synthetic resin is injected to all the corners of the cavity C even if the resin is not strongly pressurized. Since there is no need for strong pressurization, residual stresses are not generated and the warpage is not generated. Since the injection port diameter is large, the molten resin increases slightly in the part of the injection port but the heat of this part is rapidly released via the projecting part 31 of the male mold 30. Gate breakage is thus improved and a gate trace 4 does not remain high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a mold for molding a case for accommodating a disc-shaped recording medium.

[0002]

2. Description of the Related Art Conventionally, a disc-shaped recording medium used in a recording / reproducing apparatus is housed and protected in a disc cartridge to prevent damage and dust adhesion when not in use.

The applicant of the present application has previously proposed a disk cartridge of the type shown in FIGS. 3 to 5 as such a disk cartridge (Japanese Patent Application No. 02-040860, etc.). Figure 3
As shown in (A) and (B), reference numeral 101 is a case of a disk cartridge, and the case 101 is made of synthetic resin and is an upper half piece 101a of a rectangular flat housing.
And the lower half piece 101b. Case 101
A 3.5-inch optical disk 102, which is a "disk-shaped recording medium" in which optical information is recorded, is housed therein. A rotation hole 104 for rotating the optical disc 102 by a spindle motor (not shown) when the optical disc 102 is loaded in a recording / reproducing device (not shown) is formed in the center of the lower half piece 101b of the case 101. The hub portion 102a provided at the center of the optical disc 102 is exposed through the rotation hole 104. Head insertion holes 103 are formed in the upper and lower halves 101a and 101b of the case 101 so that an optical head (not shown) for reading information recorded on the optical disc 102 can be accessed.

When the optical disk 102 is not used,
A shutter 105 is attached to the case 101 to prevent dust from entering the case 101 through the rotation hole 104 and the head insertion hole 103. Shutter 105
Is formed by bending a thin metal plate of stainless steel or the like in a substantially U-shaped cross section from a substantially central portion, and an opening / closing plate portion 106 for opening and closing the rotation hole 104 and the head insertion hole 103, and a bending portion more than the opening / closing plate portion 106. Auxiliary opening / closing plate part 1 with short length
And 07.

A guide portion G formed at a portion which becomes an insertion tip when the recording / reproducing apparatus is inserted (see FIG. 3B).
As shown in FIG. 4, has a guide surface 108 formed on the left side in the figure, and the guide surface 108 extends horizontally in a position dropped from the upper end surface of the case 101. An escape recess 109 is formed on the right side of the guide surface 108 in the figure, and the opening / closing pin P is provided in the escape recess 109 by the shutter 1.
It is designed to drop when 05 is opened. The opening / closing pin P moves the shutter 105 to the right in FIG. 4, and the head insertion hole 103 is opened.

On the other hand, it is not preferable that the opening / closing pin P causes the shutter 105 to malfunction (erroneously open) when the disc cartridge is loaded in the recording / reproducing apparatus in the opposite direction. In order to prevent malfunction due to the opening / closing pin P, notches 110a, 110b into which the opening / closing pin P can be fitted are formed at the insertion tip portions of the upper half piece 101a and the lower half piece 101b, which are opposite to the guide surface 108. A pair of malfunction preventing walls 111a and 111b are formed on the notches 110a and 110b so as to be adjacent to the left side in FIG.

Bending portion 1 of shutter 105 having a substantially U-shaped cross section
On the inner surface side of 05a, a slider 112 made of synthetic resin such as polyacetal or the like, which is in sliding contact with the guide portion G, is attached,
The slider 112 has the bent portion 10 at the substantially right half in FIG.
It is fixed to the inner surface side of 5a by a tapping screw or the like. A torsion coil spring 114 for urging the shutter 105 to close the head insertion hole 103 and the like is arranged on the right side of the slider 112.

Here, the upper and lower half pieces 101a, 101
As shown in FIGS. 5 (A) and 5 (B), b has an extremely thin portion, and the thickness of the thin concave portion for label sticking shown by symbol A is about 0.8 mm in the case of 3.5 inches. In the case of 5 inches, it is about 1.2 mm. Further, reference numerals G ₁ , G ₂
Shows a gate of a hot runner mold for molding the upper and lower halves 101a and 101b, respectively. As described above, the reason for using one gate for each half piece is that if two or more gates are used, a weld mark is generated at the tip abutting portion of the molten synthetic resin injected from each gate, and the appearance is significantly impaired. This is because if there is only one gate, the weld mark will not occur.

Further, FIG. 6A shows a sectional view of a portion of the gate G ₁ of the hot runner die. FIG. 6 (A)
As shown in FIG. 7, the male mold 120a having the gate G ₁ formed therein and the female mold 120b are arranged so as to face each other to form a cavity 121. The gate G1 is filled with a molten synthetic resin J, and when the molten synthetic resin J is pressed with an appropriate pressure, the molten synthetic resin J is pressed into the cavity 121.

After the molten synthetic resin J is cooled,
When taken out from the mold, the cross section as shown in Fig. 6 (B)
It becomes the shape. That is, reference numeral 101a in FIG.
₁Is the gate G₁It is the mark of the gate of the exit of
a₂Is the gate trace 101a ₁Is the surface of the upper half piece 101a
101a₃With a drop to prevent it from protruding from
is there. The drop 101a₂The reason for providing
Including 101a₂If there is no, as shown in FIG.
At the gate trace 101a₁Is the surface 101 of the upper half piece 101a
a₃Information from a portion indicated by reference numeral B in FIG. 5 (A).
When attaching a label for information, flatten the label
This is because it cannot be done.

[0011]

By the way, FIG. 6 (A)
, The inner diameter d of the injection port of the gate G ₁ is 0.8 ±
The thickness h is 0.2 mm, and the thickness h of the portion corresponding to the drop 101a ₂ is 1.0 ± 0.2 mm. Therefore, even if the injection pressure of the molten synthetic resin J is weakened, the melted synthetic resin J is not smoothly pressed into every corner of the cavity 121. It is pressed into every corner of 121. The stress applied by the strong pressure after the molten synthetic resin J is cooled exists as “residual stress” in the upper half piece 101a, and therefore the upper half piece 101a.
There is a problem that a is warped.

Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide a molding die for a disc-shaped recording medium storage case in which the half of the case is not warped. And

[0013]

In order to achieve the above object, the present invention forms a cavity by arranging a male mold and a female mold so as to face each other and injects a molten synthetic resin into the cavity through a gate. In a mold for molding a storage case for a disk-shaped recording medium, a protrusion for reducing the thickness of the case is provided on the inner surface of the other mold facing the gate injection port of the one mold having the gate. .

[0014]

[Operation] As shown in FIGS. 1 (A) and 1 (B), a molten synthetic resin is used.
Fat J is a large gate outlet G ₀₁Into cavity C
Injected. During this injection, even if the injection pressure is not strong,
The fusion resin J is injected into every corner of the cavity C.
Therefore, since residual stress does not occur after resin curing,
Warp does not occur on one side. Also, the gate exit G₀₁Is large
Because of the size of the gate, the gate mark 4 is also large.
Heat dissipation becomes a problem. However, the inner surface 32 of the male die 30 does not project.
Since the raised portion 31 is formed, the gate trace G ₀₁Part of
The (thick part) is promptly passed through the protrusion 31.
The heat is dissipated and the molten synthetic resin cures relatively quickly.
The gate cut 4 becomes good, and the gate mark 4 becomes low.

[0015]

The present invention will be described below with reference to the illustrated embodiments. 1 (A) and 1 (B) show a cross-sectional view of a main part of a mold according to a main part of the present invention and a cross-sectional view of a lower half piece of a case molded by the mold, and FIG. 2 shows the mold. FIG. 3 is a perspective view in which a male mold and a female mold constituting the above are arranged to face each other.

First, the overall schematic structure of the mold (hot runner type) of this embodiment will be described with reference to FIG. As shown in FIG. 2, the lower half piece 101b of the case (see FIG. 5B)
The molding die M of 1. is a female die 20 having a gate G ₀ through which a molten synthetic resin (for example, polycarbonate) is injected,
And a male mold 30 having a conical protrusion 31 according to the gist of the present invention.

Next, in FIG. 1A, I-I in FIG.
An enlarged cross-sectional view including the apex of the protrusion 31 and the center line of the gate G ₀ along the line is shown. As shown in FIG. 1 (A),
The female die 20 and the male die 30 are arranged so as to face each other to form a cavity C. The female mold 20 is dropped into the mold 2 (see FIG.
A protrusion 21 for forming (B) is formed, and an injection port G ₀₁ of the gate G ₀ is formed at the center of the protrusion 21. The inner diameter D of the injection port G ₀₁ of the gate G ₀ is 1.5 m
m, which is the inner diameter of the conventional injection port shown in FIG.
8 mm), which is considerably larger.

A conical protrusion 31 is formed on the inner surface 32 of the male die 30 at a position facing the injection port G ₀₁ . The apex 31a of the protrusion 31 is
The height H from the inner surface 32 of the protrusion 31 facing the center of the injection port G ₀₁ is 0.3 mm in the case of 3.5 inches.
In case of 5 inches, the diameter is 0.5 mm, the diameter of the hem of the protrusion 31 is equal to the diameter of the injection port G ₀₁ , and the distance h between the lower surface of the protrusion 21 and the inner surface 32 is In case of 3.5 inch, it is 1.0 ± 0.2mm, and
Inch is 1.5 mm.

Next, the operation of molding the lower half of the case using the mold thus constructed will be described. Figure 1
As shown in (A), a molten synthetic resin J (for example, polycarbonate) is injected from the gate G ₀ into the cavity C. At this time, since the injection port G ₀₁ is thick as described above, the molten synthetic resin J is injected into every corner of the cavity C by a weak injection pressure. Here, since the injection pressure is sufficiently low, no residual stress is generated in the lower half piece. Further, after the injection of the molten synthetic resin J is completed, it is necessary to stand for a predetermined time and wait for the lower half piece 1 to cure. However, FIG. 1 (B)
As shown in FIG. 3, the lower half piece 1 is formed with a recess 3 corresponding to the protrusion 31, and the gap h ₀ between the upper end of the gate mark 4 and the tip of the recess 3 is narrowed. Therefore, the heat remaining on the projecting portion of the gate mark 4 is transferred to the projecting portion 31 of the male die 30 through the narrow space h ₀ and is quickly dissipated. Therefore, since the molten resin at the gate trace 4 portion is quickly radiated through the protrusion 31 as compared with the conventional case, the leaving time may be the same as the conventional case.

In this embodiment, the case of the hot runner type mold has been described, but it goes without saying that the present invention can be applied to a cold runner type mold.

[0021]

As described above, according to the present invention, a protrusion is provided on the inner surface of the opposite mold facing the injection port of the gate, and the heat radiation from the swelled portion of the resin on the gate is radiated through the protrusion. Since the diameter of the injection port of the gate can be increased and the diameter is large, the resin is injected into every corner of the cavity without applying a large force when injecting the molten resin into the cavity. Since a large force is not applied during the injection, no residual stress is generated after the case (half piece) is hardened, and the half piece is not warped. Further, since the protrusion is formed in the portion facing the gate outlet, the heat accumulated in the portion corresponding to the gate outlet is quickly dissipated to the mold through the protrusion, and the gate is broken. Get better.

[Brief description of drawings]

FIG. 1 is an enlarged view of a main part of an embodiment of the present invention, in which FIG.
Is a cross-sectional view of a mold, and (B) is a cross-sectional view of a case made of the mold.

FIG. 2 is a schematic perspective view of a mold of the embodiment.

3A and 3B are views showing a conventional disk cartridge, in which FIG. 3A is a front perspective view and FIG. 3B is a rear perspective view.

FIG. 4 is a front view of the back side of the disc cartridge.

5A and 5B are views showing a case constituting the disc cartridge, wherein FIG. 5A is a front perspective view and FIG. 5B is a rear perspective view.

6A is a cross-sectional view of a main part of a mold for manufacturing a conventional case, FIG. 6B is a cross-sectional view of a recessed part of the case manufactured by the conventional mold, and FIG. 6C is a conventional case. It is a figure explaining the inconvenience when there is no said falling part.

[Explanation of symbols]

C ... cavity G ₀ ... gate G ₀₁ ... exit M ... die 1 ... lower halves of the casing 2 ... dropped included 3 ... recess 4 ... gate mark 20 ... female die 21 ... female projections 30 ... male die 31 ... Projection 32 ... Inner surface

Claims (1)

[Claims] 1. A mold for forming a cavity by arranging a male mold and a female mold so as to face each other, and injecting a molten synthetic resin into the cavity through a gate to mold a storage case for a disk-shaped recording medium, A molding die for a disc-shaped recording medium storage case, characterized in that a protrusion for reducing the thickness of the case is provided on the inner surface of the other die facing the gate injection opening of the one die having the gate. Type.