JPH11179765A - Mold for molding disc - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a mold release unevenness, pit deviation or the like by substantially simultaneously releasing an outer peripheral ring from both a pair of molds in the case of opening the mold after molding. SOLUTION: An outer peripheral ring 4 is mounted at molds 2, 3 for forming a cavity via springs 8 or the like. The spring 8 is constituted to operate a force in a direction for opening the ring 4 and the molds 2, 3. After molten resin is cast in a mold 1, it is cooled, and the mold is opened. The ring 4 is supported to hold the ring 4 at an intermediate position between both the molds 2 and 3 by an operation of the spring 8, and the ring 4 is substantially simultaneously released from the pair of the molds 1. At this time, a molding disk 7 held by the ring 4 is substantially simultaneously released from both the molds. And, to release the ring 4 from both the molds 2, 3, the spring 8 is used, or a method of pneumatic, hydraulic pressure or the like is used. Thus, a mold release unevenness, a pit deviation or the like can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention resides in a disk molding die. More specifically, the present invention resides in a mold for injecting a synthetic resin into a mold by injection molding or the like and molding a substrate disk for an optical disk or the like.

[0002]

2. Description of the Related Art As shown in FIG. 7, a conventional disk forming die 1 comprises a fixed die 2, a movable die 3 and an outer peripheral ring 4, and stampers 5, 6 are provided on the surface of each die. Mounted. If a disk is to be molded with such a mold, a large problem occurs when the mold is opened after molding. That is, as shown in FIG. 7, the substrate is not smoothly released from the stampers 5 and 6 when the gold is opened, and uneven release and pit displacement often occur.

When the stamper 5 or 6 is attached to only one of the molds and the information of the stamper 5 or 6 is transferred to only one side of the substrate, the stamper 5 or 6 and the substrate are separated by blowing air or the like. Molding and then releasing the opposite side can prevent release unevenness to some extent, but when transferring information from the stamper to both sides of the substrate as shown in the figure, prevent release unevenness That was an extremely difficult technique.

[0004]

In the case where a stamper is provided on both sides of a mold and a disc on which information from the stamper is transferred is formed on both sides of the mold, the disc can be properly released and uneven release can be achieved. An object of the present invention is to provide a disk molding die which does not cause pit shift or the like.

[0005]

SUMMARY OF THE INVENTION The gist of the present invention is to provide a mold for molding an annular disk by injecting a synthetic resin, wherein cavities corresponding to the disk shape are formed opposite to each other. One of the pair of dies can be opened and closed, and an outer ring forming the outer peripheral portion of the disk. When the mold is opened after molding, the outer ring is removed from both of the pair of dies almost simultaneously. It has a characteristic mold for disk molding. Hereinafter, an example of the mold of the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view of one example of the mold of the present invention, FIG. 2 is a longitudinal sectional view showing the mold opening state of the mold shown in FIG. 1, and FIG. 3 is another example of the mold of the present invention. FIG. 4 is a schematic front view showing another example of the mold of the present invention, FIG. 5 is a longitudinal sectional view showing another example of the mold of the present invention, and FIG. FIG. 7 is a longitudinal sectional view showing a conventional mold. In the figure, 1 is a mold, 2 is a fixed mold, 3 is a movable mold, 4 is an outer peripheral ring, 5 and 6 are stampers, 7 is a disk, and 8 is a spring.

In the mold of the present invention, as shown in FIGS. 1 and 2, an outer peripheral ring 4 is attached to each mold forming a cavity via a spring 8 or the like. A force acts on the spring 8 in a direction in which the outer peripheral ring and each mold are separated. If the molten resin is poured into such a mold, then cooled and opened, the outer ring is supported by the action of the spring 8 so as to be maintained at an intermediate position between the two dies. The molds are almost simultaneously removed from the mold. Naturally, the molding disk 7 held by the outer peripheral ring is also peeled off from both mold surfaces almost simultaneously.

[0008] Therefore, even when the unevenness information from the stamper is transferred to both surfaces of the disk, the release is performed satisfactorily, and a good disk is manufactured without causing release unevenness and pit shift. In order for the outer peripheral ring 4 to be raised (separated) from both dies, various methods such as compressed air, hydraulic pressure, a link mechanism, and magnetic force may be used in addition to using the illustrated spring 8 or the like. is there. The mold shown in FIG. 3 shows a case where the outer peripheral ring 4 is divided into two parts.

Further, as shown in FIG. 4, a plurality of outer peripheral rings 4 are prepared, and after the mold is opened, sprue is taken out by a sprue take-out device 9 and the outer peripheral ring 4 is held on the side of the mold while holding the disk 7. , The cooling and the removal of the disk 7 are performed, during which the other outer ring 4 is moved between the molds, and the movable (rotary) outer ring 4 is prepared to perform the molding. It is possible to perform continuous molding.

FIG. 4 shows that four outer rings 4 have a rotating shaft 10.
, But the number of the outer peripheral rings may be two or more, and a structure that performs parallel movement instead of rotational movement may be used. The outer peripheral edges of the stampers 5 and 6 are covered with an outer ring 4.
This is preferable for preventing the floating of the surface. It is preferable that the surfaces of the stampers 5 and 6 and the surface of the outer peripheral ring 4 do not come into contact with each other and have a slight gap.

When the resin is introduced into the mold, the air in the mold is pushed out of the gap and discharged out of the mold, whereby the resin can be uniformly filled into the mold. The gap between the surfaces of the stampers 5 and 6 and the surfaces of the outer rings 4 and 4 'is about 1 to 30 .mu., Preferably about 3 to 20 .mu.m. Further, in order for the molded disk to be properly released from the stamper, it is a great requirement that the molded disk be cooled uniformly.

In a normal mold, an inner peripheral portion thereof is held by a stamper holder 11 to hold the stamper on the surface of the mold. For this reason, the cooling water channel 12 is not provided near the center of the mold, and the cooling of the center of the disk is insufficient, causing cooling unevenness, which causes mold release unevenness and pit shift. As shown in FIGS. 5 and 6, the stamper retainer 11 is removed (not provided).
By setting the inner peripheral edges of the stampers 5 and 6 in a free state (unfixed state) and providing the cooling water passage 12 near the center of the disk (center of the mold), it is possible to cool the formed disk uniformly.

When the inner peripheral edges of the stampers 5 and 6 are in a free state, when the resin is injected into the mold, there is a concern that the resin may flow around the back surface of the stamper. For example, as shown in FIG. 13 is provided so as to protrude about 20 μ from the surface B of the stampers 5 and 6,
The resin does not go around the back of the stampers 5 and 6. The diameter d of the bush 13 and the inner diameter D of the stampers 5 and 6 are preferably such that the inner diameter of the stampers 5 and 6 is increased by 10 to 30 μm, and a gap is formed. This is to prevent the bush 13 and the stampers 5 and 6 from being deformed by contact due to expansion and contraction. (In terms of material, the bush 13 usually has a larger expansion coefficient.)

Further, a phenomenon may be considered in which the stampers 5 and 6 are lifted from the surface of the mold at the time of release from the mold after the disk is formed. (Normal stamper thickness is 0.3mm
The following floating phenomenon can be prevented.

[0015]

According to the mold of the present invention, when the mold is opened, the outer peripheral ring holding the disk separates from the molds on both sides almost simultaneously, that is, the disk also separates from the molds on both sides almost simultaneously. Therefore, release unevenness and pit deviation are prevented, and a good disk can be stably manufactured. Also,
By preparing a plurality of peripheral rings and continuously replacing and molding, it is also possible to perform molding with high efficiency.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an example of a mold according to the present invention.

FIG. 2 is a longitudinal sectional view showing a mold opening state of the mold shown in FIG. 1;

FIG. 3 is a longitudinal sectional view of another example of the mold of the present invention.

FIG. 4 is a schematic front view showing another example of the mold of the present invention.

FIG. 5 is a longitudinal sectional view showing another example of the mold of the present invention.

FIG. 6 is a partially enlarged view of FIG. 5;

FIG. 7 is a longitudinal sectional view showing a conventional mold.

[Explanation of symbols]

 Reference Signs List 1 mold 2 fixed mold 3 movable mold 4 outer ring 5 stamper 6 stamper 7 disk

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Claims (4)

[Claims] 1. A mold for injecting a synthetic resin to form an annular disk, wherein a pair of cavities corresponding to the disk shape are formed facing each other, and at least one of the cavities is openable and closable. A disc and an outer ring forming an outer peripheral portion of the disc, wherein the outer ring is detached from both of the pair of dies almost simultaneously when the mold is opened after molding. Type. 2. The disk molding die according to claim 1, wherein a stamper for information transfer is provided on both of the pair of dies. 3. The disk molding apparatus according to claim 1, wherein the outer peripheral ring is movable to the side of the mold while holding the molded disk from between the pair of molds whose molds are opened. Mold. 4. The outer ring according to claim 3, wherein a plurality of outer rings are provided, and when one outer ring moves to the side of the mold, the other outer ring moves between the opened molds. Mold for disk molding.