JPH0957799A - Injection mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out molding of a thin disk having a suppressed warp without degrading the optical characteristics by curving surfaces of walls corresponding to surfaces of a thin disk to be molded, among the walls surrounding a space, from the inner periphery toward the outer periphery of each wall surface in accordance with the warp of the thin disk. SOLUTION: A fixed mirror 32 is formed so that a stamper bottom surface 32A has a constant slope from an inner periphery to the outer periphery such that the stamper bottom surface 32A becomes closer to a movable retainer plate 3 as the distance to the outer periphery decreases. A movable mirror 34 is formed so that a surface 34A facing a stamper 8 has the same constant slope from an inner periphery to the outer periphery as that of the stamper bottom surface 32A such that the surface 34A becomes remoter from a movable retainer plate 11 as the distance to the outer periphery decreases. Thereby, a disk having no warp as a molding and no deterioration in optical characteristics can be obtained.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. TECHNICAL FIELD The present invention (FIG. 3) Problem to be solved by the invention (FIGS. 3 and 4) Means for solving the problem (FIGS. 1, 2 and 4) Embodiment of the invention (FIG. 1, FIG. 2 and FIG. 4) Effect of the invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding die, and is particularly suitable for being applied to an injection molding die for optical disc molding.

[0003]

2. Description of the Related Art Conventionally, in an optical disk such as a compact disk, a mold having a space (cavity) having a shape corresponding to the shape of the disk to be created is used, and a molten resin is injected into the cavity of the mold. It is molded by a so-called injection molding method of solidifying.

In this case, a mold used in such an injection molding method (hereinafter, referred to as an injection molding mold) is usually
It is designed so that one plane passing through the cavities is used as a cutting plane and can be horizontally divided into two. As a result, in this type of injection mold, one mold half on the fixed side (hereinafter referred to as the fixed mold half) at the time of disk molding, the other mold half on the movable side. (Hereinafter, this is referred to as the movable-side mold half body.) A cavity can be formed by pressing the movable-side mold half body at a high pressure, and at the same time, by separating the movable-side mold half body from the fixed-side mold half body, a molded product can be obtained. It is designed to be easily removed from the inside.

FIG. 3 shows an example of the structure of a conventional injection molding die 1 used for injection molding of such an optical disk. In this injection molding die 1, the fixed-side mold half 2 has a fixed-side mold plate 3 formed in the shape of a perforated disc, and the lower surface of the fixed-side mold plate 3 is a perforated plate made of stainless steel or the like. The disk-shaped fixed-side mirror 4 is coaxially fixed.

At the center of the fixed-side mold plate 3, a spool bush 5 is fixed so that the fixed-side mold plate 3 and the fixed-side mirror 4 are integrally inserted, and the fixed-side mirror 4 is fixed. A ring-shaped holder 6 and a stamper retainer 7 are provided on the inner peripheral portion and the outer peripheral portion, respectively, so that the stamper 8 can be fixedly held by the holder 6 and the stamper retainer 7.

On the other hand, the movable-side mold half 10 has a movable-side mold plate 11 in the shape of a perforated disk, and the movable-side mold plate 1 is provided.
A movable disk-shaped mirror 12 made of stainless steel or the like and having a hole shape is coaxially fixed to the upper surface of the movable mirror 1.
An outer peripheral ring 13 is fixed to the outer peripheral portion of the outer peripheral portion 2. At the center of the movable mold plate 11 of the movable mold half body 10, the movable mold plate 11 and the movable mirror 12 are integrally movable in the axial direction of the injection molding mold 1 shown by the arrow a. A cylindrical ejector 15 is provided so as to be fitted therein, and a cylindrical cut punch 16 is provided inside the ejector 15 so as to be movable in the direction of arrow a.

As a result, in this injection molding die 1, when the movable-side mold half 10 is brought into pressure contact with the fixed-side mold half 2, the signal surface 8A of the stamper 8 and the movable-side mirror facing the signal surface 8A. The flat cavity 14 is surrounded by the one surface 12A of the outer peripheral surface 12 and the inner peripheral surface 13A of the outer peripheral ring 13.
While the cavity 14 can be formed, molten resin can be filled in the cavity 14 through the through hole 5A of the sprue bush 5.

In this injection molding die 1, after the molten resin filled in the cavity 14 is solidified, the movable punch half 10 is pressed against the fixed punch half 2 and the cut punch 16 is pressed. By ascending, the sprue at the center of the molded disk 20 can be punched out, and thereafter the movable side mold half body 10 is moved in the direction away from the fixed side mold half body 2 to move the ejector 15 to the fixed side mold. The molded disk can be taken out from the cavity 14 of the injection mold 1 by projecting it toward the half body 2.

The fixed side mirror 4 and the movable side mirror 12
The water channels 4B and 12B are respectively provided in the interior of the container, and hot water of about 80 to 120 [° C] is constantly supplied to each of these channels 4B and 12B from a temperature controller (not shown). Fixed mold half 2 with warm water
Further, the temperature distribution of the movable-side mold half body 10 is kept constant, and the solidification of the molten resin filled in the cavity 14 can be promoted. See also sprue bush
A water channel 5B is also provided inside, and hot water of about 40 [° C] is sequentially supplied to the water channel 5B.

Incidentally, on the signal surface of the disk thus formed, a reflective film is then sequentially formed by a sputter or the like, and a protective film is sequentially formed by a spin coat or the like. Thereby, a desired optical disk can be obtained.

[0012]

By the way, there are various standards for optical discs such as compact discs depending on the type, and one of them is a standard for warpage. In this case, it is generally desirable that the optical disk be flat, but in reality, there are various causes as shown in FIG.
As shown in FIGS. 4A and 4B, the signal reading surface 20A side or the signal surface 20B of the disk 20 manufactured by injection molding.
Warpage occurs on the side.

The first cause of such warpage is as follows.
Signal reading surface 2 of disk 20 created by injection molding
The 0A side directly contacts the movable-side mirror 12 (FIG. 3), while the signal surface 20B side contacts the fixed-side mirror 4 via the stamper 6, which may cause a problem.

That is, in the injection molding die 1, the stamper 4 is merely pressed against the suntapa mounting surface 4A of the fixed-side mirror 4 by the stamper holder 7 of the fixed-side mold half 2, and therefore the cavity 14 is provided. There is a loss in heat transfer from the molten resin to the fixed-side mirror 4 when the molten resin therein solidifies, and as a result, the cavity 14 is solidifying.
It is conceivable that a warp may occur in the disk 20 due to a difference between the contraction of the disk 20 on the signal surface 20B side and the contraction of the disk 20 on the signal reading surface 20A side.

As the second cause, as is clear from FIG. 3, the injection mold 1 has a different structure between the fixed mold half 2 and the movable mold half 10, and further the spool. There may be a problem due to a temperature difference between the hot water supplied to the water passage 5A of the bush 5 and the hot water supplied to the water passage 4B of the fixed-side mirror 4 and the water passage 12A of the movable-side mirror 12, respectively. For this reason, this type of injection mold 1
In the above, there is a difference in heat transfer efficiency between the signal surface 20B side of the molded disk 20 and the inner peripheral portion of the signal reading surface 20A side, and as a result, shrinkage of the molded disk 20 on the signal surface 20B side. It is conceivable that a warp may occur due to the difference between the contraction on the signal reading surface 20A side and the contraction on the signal reading surface 20A side.

As a third cause, in the injection-molded disc 20, the fixed-side mold half 2 is provided on the signal surface 20B side.
While the concave portion 20BX (FIG. 4) is formed due to the existence of the stamper holder 6, the convex portion called an elevation is provided on the signal reading surface 20A side to prevent the discs 20 from sticking to each other when stacked. A problem due to the formation of the portion 20AX can be considered. Therefore, in this type of disk 20, it is considered that a difference in contraction easily occurs between the signal surface 20B side and the signal reading surface 20A side, and as a result, warpage may occur.

As a fourth cause, the injection-molded disk 20 is moved from the movable mold half body 10 to the edge ejector 16.
There may be a problem with taking it out by sticking it out with. In other words, by doing this
It is considered that 0 may warp. As one method for reducing the warp of the disk 20 caused by such various causes (hereinafter, referred to as a first warp reduction method), conventionally, the fixed-side mirror 4 of the injection molding die 1 is used.
One temperature controller is connected to each of the movable side mirror 12 and the movable side mirror 12, and the temperature of the hot water supplied to the water channel 4B of the fixed side mirror 4 and the temperature of the hot water supplied to the water channel 12B of the movable side mirror 12. A method of making a difference is proposed.

However, according to such a first warp reduction method, a temperature difference occurs between the fixed side mirror 4 and the movable side mirror 12 of the injection molding die 1, so that the molten resin supplied into the cavity 14 is solidified. When this is done, distortion is likely to remain inside the molten resin (inside the disk 20), and as a result it is difficult to keep the birefringence value required for the optical disk within the allowable range. Further, according to such a first warp reduction method, two temperature controllers for hot water flowing through the respective water passages 4B, 12B of the fixed side mirror 4 and the movable side mirror 12 of the injection molding die 1 are required. There is a problem that the equipment cost required for manufacturing the disk 20 becomes high.

The present invention has been made in view of the above points, and it is an object of the present invention to propose an injection molding die capable of molding a thin disk with less warpage without deteriorating optical characteristics.

[0020]

In order to solve such a problem, in the present invention, an injection molding die having a space corresponding to a desired thin-walled disc shape, which is used as a die for injection-molding a thin-walled disc. In a peripheral wall of the space, a first wall surface corresponding to one surface of the thin-walled disk to be formed and a second wall surface corresponding to the other surface of the thin-walled disk are provided in accordance with the warp of the thin-walled disk. Each of them is formed so as to curve from the inner circumference to the outer circumference or be inclined at a constant angle.

Among the peripheral walls of the space, a first wall surface corresponding to one surface of the thin-walled disk to be formed and a second wall surface corresponding to the other surface of the thin-walled disk are provided in accordance with the warp of the thin-walled disk. Since the space is formed so as to be curved or uniformly inclined from the inner circumference to the outer circumference, the space itself can be curved or uniformly inclined from the inner circumference to the outer circumference. Therefore, a thin disk with little or no warpage can be obtained as a molded product.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

In FIG. 1, in which parts corresponding to those in FIG. 3 are designated by the same reference numerals, numeral 30 generally indicates an injection mold according to the embodiment, and the fixed side mirror 32 and the movable side of the fixed side mold half body 31. FIG. 3 except for the movable mirror 34 of the mold half 33.
The injection molding die 1 has the same structure. That is, in the case of this injection molding die 30, as is apparent from FIG. 1, the fixed-side mirror 32 has a stamper mounting surface 32A that is closer to the fixed-side mold plate 3 as the stamper mounting surface 32A is closer to the outer peripheral portion. It is formed with a constant inclination from the circumference to the outer circumference.

On the other hand, in the movable side mirror 34, the one surface 34A facing the stamper 8 is separated from the movable side template 11 toward the outer peripheral portion, so that the one surface 34A faces the stamper of the fixed side mirror 32 from the inner periphery to the outer periphery. It is formed with the same constant inclination as the mounting surface 32A. As a result, in this injection molding die 30, when the movable-side die half body 33 is brought into pressure contact with the fixed-side die half body 31, it is possible to form the cavity 35 that is constantly inclined from the inner circumference to the outer circumference. It is done like this.

In this case, the inclination amount of the cavity 35 is set so that the molded disk 20 (FIG. 4) is warped toward the signal reading surface 20B side due to various causes as described above, and the warp can be canceled. The inclination amount of the stamper mounting surface 32A of the fixed-side mirror 32 and the one surface 34A of the movable-side mirror 34 facing the fixed-side mirror 32 is selected so that the warp of the molded disk 20 can be canceled. As a result, in this injection molding die 30,
As a molded product, a flat disk 20 having no warp can be obtained.

In the case of this embodiment, the fixed side mirror 32 and the movable side mirror 34 are provided with water passages 32B and 34B, respectively, and hot water of a predetermined temperature is sequentially supplied to these water passages 32B and 34B from a temperature controller (not shown). It is designed to be supplied. As a result, in this injection molding die 30, the temperature distribution of the fixed-side mold half 2 and the movable-side mold half 10 is kept constant as in the conventional injection molding mold 1 (FIG. 3), and The solidification of the molten resin filled in the cavity 14 can be promoted.

In practice, the injection molding die 30 includes a stamper mounting surface 4A of the fixed-side mirror 4 of the conventional injection molding die 1 shown in FIG. 3 and a movable-side mirror 12 opposed to the stamper mounting surface 4A. It can be formed by shaving the one surface 12A of the fixed side mirror 4 and inclining the stamper mounting surface 4A of the fixed side mirror 4 and the one surface 12A of the movable side mirror 12.

In this case, the amount of inclination given to the stamper mounting surface 4A of the fixed-side mirror 4 and the one surface 12A of the movable-side mirror 12 is such that the disk 2 molded using the conventional injection molding die 1 is used.
It may be adjusted by gradually cutting according to the warp amount of 0 (actually, it may be cut by about 0.1 [mm]), whereby an injection molding die 30 capable of accurately molding the flat disk 20 is obtained. be able to.

With the above structure, the injection molding die 3
At 0, the stamper mounting surface 32A of the fixed-side mirror 32 and the one surface 34A of the movable-side mirror 34 facing the stamper mounting surface 32A are inclined to such an extent that the warp of the molded disk 20 can be canceled, and accordingly from the inner circumference to the outer circumference. It is possible to form the cavities 35 that are inclined in a constant direction. Therefore, by molding the disk 20 using this injection molding die 30, a flat disk 20 having no warp as a molded product is obtained.
(FIG. 4) can be obtained.

In this case, in this injection molding die 30, it is not necessary to make a temperature difference between the fixed side mirror 32 and the movable side mirror 34 at the time of molding the disk 20 as in the first warp reduction method described above, and therefore the molding is performed accordingly. The birefringence of the disk 20 obtained as a product can be easily and surely kept within the allowable range. Further, this injection molding die 30 does not require two temperature controllers unlike the above-described first warp reduction method, so that the equipment cost required for manufacturing the disk 20 is suppressed and the manufacturing cost of the optical disk is reduced. You can also avoid rising.

According to the above construction, the stamper mounting surface 32A of the fixed-side mirror 32 and the one surface 34 of the movable-side mirror 34.
By forming A with a constant inclination from the inner circumference to the outer circumference, a disk 20 having no warp and no deterioration in optical characteristics can be obtained as a molded product, thus deteriorating the optical characteristics. It is possible to realize an injection molding die that can mold a disk with less warpage without causing any distortion.

In the above-described embodiment, the fixed mirror 3 is so arranged that the cavity 35 warps upward in FIG.
2 stamper mounting surface 32A and the stamper mounting surface 32
The case where the one surface 34A of the movable-side mirror 34 that faces the A via the stamper 8 is formed with a certain inclination has been described, but the present invention is not limited to this, and the molded disk 20 (FIG. 4) is not limited thereto. ), The fixed side mirror 3
The second stamper mounting surface 32A and the one surface 34A of the movable side mirror 34 may be formed so as to curve upward from the inner circumference to the outer circumference.

Further, in the above-mentioned embodiment, it is assumed that the molded disk 20 warps toward the signal reading surface 20A side as shown in FIG. 4A, and the stamper mounting surface 32A of the fixed side mirror 32 and the stamper mounting surface. The case where the one surface 34A of the movable side mirror 34 facing the 32A is inclined in the upward direction in FIG. 1 has been described, but the present invention is not limited to this, and for example, the molded disk 20 is shown in FIG.
In the case where the signal surface 20B is warped as shown in FIG. 2B, the stamper of the fixed-side mirror 42 of the fixed-side mold half 41 is stamped as shown in FIG. Mounting surface 4
2A and one surface 44A of the movable-side mirror 44 of the movable-side mold half 43 facing the 2A may be formed so as to be inclined or curved in a constant downward direction. By doing so, The same effect as that of the embodiment can be obtained.

Further, in the above-described embodiment, the stamper mounting surface 32A of the fixed side mirror 32 and the one surface 34A of the movable side mirror 34 facing the stamper mounting surface 32A are molded.
Although the case where the tilt amount is selected so that the warp of 0 can be canceled has been described, the present invention is not limited to this, and the disk 20 is fixed so as to be tilted or curved to some extent in the warp direction. The stamper mounting surface 32A of the side mirror 32 and the one surface 34A of the movable side mirror 34 that faces the stamper mounting surface 32A may be formed. By doing so, the warp of the molded disk 20 is completely canceled. Even if it is not possible, it is possible to reduce the warp of the disk 20 to some extent, and thus it is possible to realize an injection mold that can mold the disk 20 with less warp without deteriorating the optical characteristics.

Further, in the above-mentioned embodiment, the present invention is applied to the injection molding die 3 for the disc 20 which is the basis of the optical disc.
Although the present invention is not limited to this, the point is that the present invention has a space corresponding to a desired thin-walled disc shape, which is used as a mold when injection-molding a thin-walled disc. In the injection-molding die, among the peripheral walls of the space, a first wall surface corresponding to one surface of the thin disk to be molded and a second wall surface corresponding to the other surface of the thin disk,
If it is formed so as to curve from the inner circumference to the outer circumference or be inclined at a constant angle, it can be applied to various other injection molding dies.

[0036]

As described above, according to the present invention, in an injection molding die which has a space corresponding to a desired thin disk shape inside, which is used as a metal mold when injection molding a thin disk, Among the peripheral walls, a first wall surface corresponding to one surface of the thin-walled disk to be formed and a second wall surface corresponding to the other surface of the thin-walled disk are respectively arranged from the inner circumference to the outer circumference in accordance with the warp of the thin-walled disk. Since it is formed so as to be curved or inclined at a constant angle toward, it is possible to obtain a thin disk with little or no warpage as a molded product, and thus less warpage without deteriorating the optical characteristics. It is possible to realize an injection molding die capable of molding a thin disk.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of an injection molding die according to an embodiment.

FIG. 2 is a cross-sectional view showing a configuration of an injection molding die according to another embodiment.

FIG. 3 is a cross-sectional view showing a configuration of a conventional injection molding die.

FIG. 4 is a cross-sectional view for explaining the warp of an injection-molded disk.

[Explanation of symbols]

20 ... disk, 20A ... signal reading surface, 20B ...
Signal surface, 30, 40 ... Injection mold, 31, 41 ...
Fixed mold half, 32, 42 ... Fixed mirror, 32
A, 42A ... Stamper mounting surface, 33, 43 ... Movable side mold half, 34, 44 ... Movable side mirror, 34A, 44
A ... One side, 8 ... Stamper, 35,45 ... Cabinet.

Claims (2)

[Claims] 1. An injection molding die, which is used as a die when a thin disk is injection-molded and has a space having a shape corresponding to a desired shape of the thin disk, which is formed among the peripheral walls of the space. A first wall surface corresponding to one surface of the thin-walled disk and a second wall surface corresponding to the other surface of the thin-walled disk are curved or constant from the inner circumference to the outer circumference in accordance with the warp of the thin-walled disk. An injection molding die, characterized in that it is formed so as to be inclined. 2. The direction and amount of the curvature or inclination of the first and second wall surfaces are selected as the direction and amount of the warp generated in the thin disk to be molded. The injection mold according to claim 1.