JP3640121B2 - Disk cartridge shell and lower shell molding method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a disk cartridge shell for storing a disk such as a mini disk in an upper shell and a lower shell, and a lower shell molding method thereof, and more particularly, a disk cartridge shell having improved lower shell flatness and a lower shell molding method thereof. About.
[0002]
[Prior art]
A small magneto-optical disk, for example, a mini disk (hereinafter referred to as “MD”) is a recording medium in which data is recorded and reproduced while being rotated by being inserted into a recording and reproducing device such as a deck while being accommodated in a cartridge shell. is there.
Therefore, the flatness of the cartridge shell is an important factor in order for the MD to achieve normal rotation and recording / reproduction.
[0003]
In the current MD cartridge shell, the lower shell 100 shown in FIG. 10 and the upper shell 101 shown in FIG. 11 are opposed to each other, and the lower shell 100 and the upper shell 101 are joined together with the MD (not shown) stored inside. It is configured.
As a mode of warping between the lower shell 100 and the upper shell 101, as shown in FIG. 12A, a state of warping outside the shell (outward warping) and a state shown in FIG. Thus, there is a state of warping inward (inward warping), but in order to suppress these warpings as much as possible, the standard of flatness between the lower shell 100 and the upper shell 101 has become an accuracy of 1/100 mm level. Yes.
Specifically, it is desired that the flatness standard of the upper shell 101 is −0.1 ± 0.1 and accuracy of −0.1. However, the lower shell 100 is required to have a flatness standard of −0.01 ± 0.06 with an accuracy of almost 0 mm (flat), and requires an extremely high flatness compared to the upper shell 101.
[0004]
The lower shell 100 and the upper shell 101 are formed by injection molding a predetermined synthetic resin (PC, ABS resin, etc.).
Specifically, in the plasticizing step, the synthetic resin is melted so as to be injection-molded, and in the injection step, the molten synthetic resin is poured into a mold. Thereafter, in the pressure holding process, the deformation is compensated before the molten synthetic resin injected into the mold is solidified. In the cooling step, the synthetic resin is cooled and solidified until the molded product has a sufficient strength when released.
The molded product thus injection-molded is taken out by opening the mold, and the above series of steps are repeated and continuously manufactured by closing the mold.
[0005]
In the injection molding as described above, the flatness adjustment of the lower shell 100 and the upper shell 101 is performed in the pressure holding step.
In other words, the pressure holding step is a step of compensating for the deformation of the molded product as described above, and adjusting and maintaining the flatness of the lower shell 100 and the upper shell 101 by adjusting the holding pressure and the holding time. Do.
[0006]
[Problems to be solved by the invention]
However, the conventional techniques described above have the following problems in obtaining high-precision flatness.
The flatness measurement of the lower shell 100 is performed at points L1 and L2 shown in FIG. 10, and the flatness measurement of the upper shell 101 is performed at points U1 and U2 shown in FIG.
Although the lower shell 100 and the upper shell 101 have thin and uneven structures, the point L1 of the lower shell 100 is the most difficult to obtain flatness in the injection molding.
In the injection molding, the flatness of the lower shell 100 shows a tendency of inward warping at the point L1, and shows a tendency of outward warping at the point L2.
Therefore, in the pressure holding step of the injection molding, the pressure holding conditions such as the pressure holding time and the pressure holding time are set so that the point L1 is warped outward.
However, when the pressure holding condition is set so as to compensate the inward warping of the point L1 in the outward warping direction, the flatness of the point L1 becomes the desired accuracy, but the lower shell 100 generally swings in the outward warping direction. It warps greatly outward, and deviates greatly from the standard.
As described above, in the conventional technique, the difference between the flatness at the point L1 and the flatness at the point L2 is always maintained at a constant large value regardless of how the warp directions of the point L1 and the point L2 are adjusted. In addition, high-precision flatness cannot be obtained for the entire lower shell 100.
On the other hand, it may be possible to increase the flatness of the entire lower shell 100 by providing a complicated special mechanism in the injection mold. However, providing such a special mechanism is not preferable because it causes an increase in equipment cost and leads to an increase in product cost.
[0007]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a cartridge shell of a disk and its lower shell capable of increasing the flatness of the cartridge shell without providing a special mechanism in the injection mold. The object is to provide a molding method.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the present invention comprises an upper shell and a lower shell, and the lower shell includes a thin shutter portion that is recessed on the outer surface side of the lower shell, and a thick disk storage portion. In this embodiment, a thin portion having a thickness that is recessed on the inner surface side of the lower shell and having substantially the same thickness as the shutter portion is formed in the disc storage portion while leaving the peripheral portion of the disc storage portion as long as the disc can be placed.
According to such a configuration, a thin portion having the same thickness as the shutter portion is formed in the disk storage portion of the lower shell, and the shutter portion and the disk storage portion are warped in substantially the same direction.
[0009]
The present invention also relates to an injection molding die in a lower shell molding method of a cartridge shell for molding a lower shell having a thin shutter portion and a thick disc storage portion which are recessed on an outer surface. Of the mold block of the mold is located on the inner surface side of the lower shell and the protrusion of a predetermined shape is provided on the surface of the block on which the disk storage part can be molded, so that the peripheral part of the disk storage part is the width that can be placed on the disk The thin part that is recessed on the inner surface side of the lower shell and has the same thickness as the shutter part is formed in the disk storage part.
According to such a configuration, the thin block portion having the same thickness as the shutter portion in the disk storage portion is formed by the block having a predetermined-shaped protrusion located on the inner surface side of the lower shell among the mold blocks of the injection mold. Therefore, the difference in post-shrinkage due to the product thickness difference can be eliminated, and the shutter portion and the disc storage portion are warped in the same direction.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The cartridge shell of the disk of this embodiment is an MD (mini disk) cartridge shell, and consists of a lower shell and an upper shell.
1 is an internal view showing a lower shell of the cartridge shell of this embodiment, FIG. 2 is an external view, and FIG. 3 is a cross-sectional view taken along line AA in FIG.
[0011]
The lower shell 1 is a rectangular case having a thickness of 1 mm, and a mating surface portion 1a with an upper shell, which will be described later, projects from the inner periphery of the case, and a round window 3 (center hole) is formed in the center. In the vicinity of the round window 3, a square window 4 is formed.
On the inner side surface of the lower shell 1, as shown in FIG. 1, a ring-shaped disk storage portion 5 for storing an MD (not shown) is defined.
Specifically, an inner ring wall 10 having a diameter substantially equal to that of the center hole of the MD is provided so as to surround the round window 3, and an outer ring wall 11 having a radius of 33 mm is provided outside the inner ring wall 10. An area defined by the inner ring wall 10 and the outer ring wall 11 is the disc storage portion 5, and the thickness thereof is set to 1 mm.
On the other hand, as shown in FIG. 2, a shutter portion 6 including a square window 4 is recessed in the outer surface of the lower shell 1.
The shutter portion 6 is a portion into which a shutter (not shown) that opens and closes the square window 4 is fitted, and as shown in FIG. 3, the wall thickness S is set to 0.6 mm.
That is, the wall thickness difference d between the wall thickness S of the shutter section 6 and the wall thickness D of the disk storage section 5 is 0.4 mm.
[0012]
The lower shell 1 including the disk storage portion 5 and the shutter portion 6 as described above is formed with a thin portion 50 which is a main portion of the embodiment.
As shown in FIG. 1, the thin portion 50 is formed by stealing the meat of the disc storage portion 5, has a substantially U shape, and its thickness is set to 0.6 mm, which is equal to the shutter portion 6. Yes.
Specifically, the thin portion 50 includes a semicircular portion 51 and extending portions 52 and 53 extending from the end of the semicircular portion 51 in the direction of the shutter portion 6.
The inner radius R1 of the semicircular portion 51 is set to 12.5 mm, and the outer radius R2 is set to 24 mm. That is, the semicircular portion 51 has a width of 11.5 mm.
The extending part 52 has a rectangular shape with the same width as the semicircular part 51, and the leading edge (the upper end in FIG. 1) reaches the vicinity of the shutter part 6. The corners on both sides of the leading edge are rounded with a radius of curvature of 3 mm.
The extending portion 53 has a substantially triangular shape with the base end having the same width as the semicircular portion 51, and the right edge of the extending portion 53 extends straight up to the vicinity of the square window 4. The left edge is curved with the same curvature as the outside of the semicircular portion 51, and the tip is rounded with a curvature radius of 1.5 mm.
Thereby, the boundary between the extension part 52 and the shutter part 6, the boundary between the extension part 53 and the shutter part 6, between the inner edge of the thin part 50 and the inner ring wall 10, and the outer edge and outer ring of the thin part 50. A thickness of 1 mm remains between the wall 11 and the thick part receives MD. Further, since the MD may be damaged when the MD is received by the thick portion of the disc storage portion 5, the boundary portion 55 between the disc storage portion 5 and the thin portion 50 is inclined as shown in FIG. Is formed.
In this way, the thin portion 50 equal to the thickness S of the shutter portion 6 occupies most of the disc storage portion 5.
[0013]
FIG. 4 is an external view showing the upper shell of the cartridge shell of this embodiment.
The upper shell 2 is the same as the conventional upper shell 101 shown in FIG. 11, and includes a square window 24 and a shutter part 26 corresponding to the square window 4 and the shutter part 6 of the lower shell 1, and a concave part 20 for attaching a label. On the outer surface side.
[0014]
Next, a method for forming the lower shell 1 applied to the cartridge shell of this embodiment will be described.
FIG. 5 is a cross-sectional view of a mold block of an injection mold for molding the lower shell 1 as viewed from the front, and FIG. 6 is a cross-sectional view as viewed from the side.
In the mold block shown in FIGS. 5 and 6, reference numeral 7 denotes a movable side mold plate, and reference numeral 8 denotes a fixed side mold plate.
[0015]
The movable side mold plate 7 is movable up and down in the figure, and opens and closes the mold by the vertical movement.
A core block 70 is assembled to the movable side template 7 integrally with the surrounding core block 71.
7 is a top view of the core block 70, and FIG. 8 is a cross-sectional view taken along the line BB in FIG.
The core block 70 is a block for forming the inner surface side of the lower shell 1 shown in FIG. 1, and the unevenness of the upper surface thereof is opposite to the unevenness of the inner surface of the lower shell 1.
Therefore, a protrusion 72 corresponding to the thin portion 50 of the lower shell 1 is provided on the upper surface of the core block 70. As shown in FIG. 8, the protrusion height h of the protrusion 72 is set to 0.4 mm corresponding to the step between the disk storage portion 5 and the thin portion 50 of the lower shell 1.
[0016]
On the other hand, as shown in FIGS. 5 and 6, a cavity block 80 is assembled to the fixed-side template 8.
FIG. 9 is a bottom view of the cavity block 80.
The cavity block 80 is a block for forming the outer surface side of the lower shell 1 shown in FIG. 2, and the unevenness of the lower surface thereof is opposite to the unevenness of the outer surface of the lower shell 1.
As shown in FIGS. 5 and 6, a core 87 is incorporated between the cavity block 80 and the core block 70 to mold the round window 3 of the lower shell 1. Although not shown, a core for molding the square window 4 is also incorporated between the cavity block 80 and the core block 70.
[0017]
The synthetic resin, which is the material of the lower shell 1, is injected into the gap between the core block 70 and the cavity block 80. In this embodiment, the injection direction is characterized.
In FIG. 6, reference numeral 74 denotes a submarine gate. The submarine gate 74 is formed by a passage 74 a that is hidden from the side of the core block 70 and a passage 74 b that communicates with the passage 74 a and opens on the upper surface of the core block 70. Yes.
As a result, the molten synthetic resin injected from above the fixed-side template 8 and reaching the gap 78 between the core block 71 and the cavity block 80 is inserted into the gap between the core block 70 and the cavity block 80 via the submarine gate 74. Injected.
As shown in FIG. 7, two such submarine gates 74 are provided on both sides of the central axis L of the core block 70.
That is, since the round window core 87 and the square window core are arranged on the central axis L of the core block 70, the synthetic resin injection space between the core block 70 and the cavity block 80 is substantially symmetrical with respect to the central axis L. It becomes space. Therefore, when the molten synthetic resin is injected from the two submarine gates 74 located on both sides of the central axis L, a weld line where the molten synthetic resin injected from each of the submarine gates 74 is formed on the central axis L. . For this reason, the flow balance of the molten synthetic resin flowing on both sides of the central axis L becomes uniform.
[0018]
The lower shell 1 is formed by injection molding using the above mold block.
The process is the same as in the case of the prior art described above, and the molten synthetic resin is injected into the mold block shown in FIGS. 6 and 6 through a plasticizing process and an injection process.
Then, as described above, the molten synthetic resin is injected from the two submarine gates 74 into the lower shell forming space between the core block 70 and the cavity block 80 with a uniform flow balance.
Thereafter, the process proceeds to a pressure holding step to compensate for the deformation of the injected molten synthetic resin.
Conditions such as holding pressure and holding time at this time are set so that the thin portion of the lower shell 1, that is, the thin portion 50 and the shutter portion 6 are prevented from warping and become flat.
Under this pressure holding condition, since the entire disk storage portion 5 that conventionally occupies 70% or more of the lower shell 1 is thick, the inner warp of the disk storage portion 5 is increased, and sufficient flatness can be obtained. could not.
In contrast, in this embodiment, the thin portion 50 and the shutter portion 6 are molded so as to be as thin as 0.6 mm, and the thin portion 50 is U-shaped and occupies most of the disk storage portion 5. Therefore, even if the pressure holding condition is set so as to suppress the outward warping between the thin portion 50 and the shutter portion 6, the remaining small-area thick portion hardly undergoes internal warping, and the entire lower shell 1 Flatness increases.
Through the pressure-holding step and the cooling step as described above, the molding of the lower shell 1 having high flatness is completed.
[0019]
Thus, according to this embodiment, since the thin portion 50 is provided in the disk storage portion 5 of the lower shell 1, the material cost can be reduced correspondingly, and the flatness of the entire lower shell 1 can be highly accurate. Can be Moreover, since the thin part 50 can be shape | molded only by providing the protrusion part 72 in the core block 70 of a metal mold block, the increase in installation cost is not caused.
[0020]
【The invention's effect】
As described in detail above, according to the cartridge cartridge shell of the present invention, the thin shell portion having the same thickness as the shutter portion is formed in the disk storage portion of the lower shell, and the warp between the shutter portion and the disk storage portion is formed. Since they are in the same direction, there is an excellent effect that the flatness of the entire lower shell can be improved. Further, since the disk storage portion is thinned, the material can be reduced correspondingly, and as a result, the cost of the product can be reduced.
[0021]
Further, according to the lower shell molding method of the present invention, the warp of the shutter portion and the disk storage portion can be made in the same direction without providing a complicated special mechanism in the mold block of the injection mold. There is an effect that the flatness of the lower shell can be made highly accurate without increasing the equipment cost.
[Brief description of the drawings]
FIG. 1 is an inner surface view showing a lower shell of a cartridge shell according to an embodiment of the present invention.
FIG. 2 is an external view showing a lower shell of the cartridge shell according to the embodiment of the present invention.
FIG. 3 is a cross-sectional view taken along the line AA in FIG.
FIG. 4 is an external view showing an upper shell of a cartridge shell of the disk of this embodiment.
FIG. 5 is a sectional view of a mold block of an injection mold for molding a lower shell as seen from the front.
FIG. 6 is a cross-sectional view of a mold block of an injection mold for molding a lower shell as viewed from the side.
FIG. 7 is a top view of the core block.
8 is a cross-sectional view taken along the line BB in FIG.
FIG. 9 is a bottom view of the cavity block.
FIG. 10 is an external view of a lower shell in a cartridge shell according to a conventional example.
FIG. 11 is an external view of an upper shell in a cartridge shell according to a conventional example.
FIGS. 12A and 12B are schematic views showing a state of warping of the shell, in which FIG. 12A shows an outward warping state and FIG. 12B shows an inward warping state.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Lower shell, 2 ... Upper shell, 3 ... Round window, 4 ... Square window, 5 ... Disc storage part, 6 ... Shutter part, 50 ... Thin part, 51 ... Semicircular part, 52, 53 ... Extension part.

Claims (4)

In a cartridge cartridge shell of a disk comprising an upper shell and a lower shell, wherein the lower shell comprises a thin shutter part recessed on the outer surface side of the lower shell, and a thick disk storage part.
A thin portion having a thickness that is recessed on the inner surface side of the lower shell leaving the peripheral portion of the disc storage portion as much as a disc-mountable width and having substantially the same thickness as the shutter portion is formed in the disc storage portion.
A cartridge shell of a disc characterized by the above. The cartridge shell of the disk according to claim 1,
The thin-walled portion is formed in a substantially U shape extending from the vicinity of one end of the shutter portion to the vicinity of the other end so as to surround the central hole of the disk storage portion.
A cartridge shell of a disc characterized by the above. In the lower shell molding method of the cartridge shell, which is a mold for injection molding, molding a lower shell comprising a thin shutter portion recessed on the outer surface and a thick disc storage portion,
A peripheral edge of the disc storage portion is provided by providing a predetermined shape projecting portion on the surface of the block that can be molded on the inner surface of the lower shell of the mold block of the injection mold. Forming a thin portion in the disc storage portion that is recessed on the inner surface side of the lower shell, leaving a portion where the disc can be placed, and having substantially the same thickness as the shutter portion.
A method for molding a lower shell of a cartridge shell. The lower shell molding method of the cartridge shell according to claim 3,
The thin portion is formed in a substantially U shape extending from the vicinity of one end of the shutter portion to the vicinity of the other end so as to surround the center hole of the disc storage portion.
A method for molding a lower shell of a cartridge shell.

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