JPH08238649A - Mold and method for molding disk substrate - Google Patents

Abstract

PURPOSE: To easily attach a stamper to the cavity forming surface of a disk mold. CONSTITUTION: In a mold for molding a disk substrate constituted so that a stamper is held to the cavity forming surface 42 of a mold 24 under suction, the guide sleeve 54 protruding form the central part of the cavity forming surface 42 so that the center hole of the stamper 44 is fitted to the outer peripheral surface of the sleeve to position the stamper 44 is provided so as to be reciprocally movable in the protruding direction.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a mold and a molding method for a disk substrate used for manufacturing an optical disk, a magneto-optical disk and the like, and more particularly to a mold and a molding method for a disk substrate for molding a disk substrate using a stamper. It is about.

[0002]

BACKGROUND ART Generally, a disk substrate used for manufacturing an optical disk, a magneto-optical disk, or the like is manufactured by using a fixed mold and a movable mold which are fitted to each other to form a molding cavity. At least one of the mold and the movable mold has an annular plate-shaped stamper for forming a pregroove forming a concave / convex pattern (pit) corresponding to an information signal and a recording track on the cavity forming surface of the mold. By filling a predetermined resin material into the molding cavity.

By the way, in a molding die for forming a disk substrate, as disclosed in Japanese Patent Publication No. 5-13537, the inner peripheral edge of the stamper is fixed by a stamper retainer screwed to the die. By pressing the part, the stamper is positioned and held on the cavity forming surface, but in recent years, in order to facilitate mounting and replacement of the stamper, the inner peripheral edge of the stamper is exposed to negative pressure air or magnetic force. A mold has been proposed which is sucked and adsorbed to be held on the cavity forming surface. In addition, in such a molding die, as shown in FIG.
A circular positioning projection 14 is provided at the center of the cavity forming surface 12 on which the positioning projection 1 is mounted.
The stamper 10 is positioned by fitting the center hole 16 of the stamper 10 to the outer peripheral surface of the stamper 10. In FIG. 4, reference numeral 18 denotes an air passage, and the negative pressure suction force is exerted on the back surface of the stamper 10 through the air passage 18.

However, extremely high accuracy is required for positioning the stamper 10, and it is necessary to prevent the resin material from entering between the fitting surfaces of the positioning projection 14 and the center hole 16 of the stamper 10. From the positioning protrusion 14
It is designed so that there is almost no gap between the outer peripheral surface of the stamper 10 and the center hole 16 of the stamper 10, and it was difficult to fit the positioning protrusion 14 when the stamper 10 was mounted. In addition, in order to secure the thickness of the central portion of the disk substrate and the flowability of the resin material to be filled, the protruding tip end surface of the positioning protrusion and the surface of the stamper 10 are generally flush with each other. Since the protrusion height of the positioning protrusion 14 is set to be substantially the same as the thickness of the stamper 10, the positioning protrusion 14
Has a very small protrusion height of 0.3 mm or less, and it is difficult to visually confirm whether or not the stamper 10 is properly fitted to the positioning protrusion 14 when mounted.
In many cases, the positioning protrusion 14 does not fit well into the center hole 16 of the stamper 10 and is caught on the outer peripheral edge portion of the positioning protrusion 14 to start the disk molding while the upper portion of the positioning protrusion 14 is on the resin. Stamper 10 by filling pressure of
However, there was a problem that it was easily deformed and damaged.

In order to cope with such a problem, for example, as shown in FIG. 5, an annular guide protrusion 20 is provided on the outer peripheral edge of the positioning protrusion 14 so that the guide is provided when the stamper 10 is mounted. The central hole 1 of the stamper 10 on the outer peripheral surface of the protrusion 20
6 may be guided, but when such a guide protrusion 20 is formed, the flow of the resin material filled in the molding cavity is adversely affected, and birefringence and the like are easily deteriorated. Since the annular concave portion is formed only on one surface of the disk substrate by 20, the product defect such as warpage is apt to occur due to cooling shrinkage of the resin. Moreover, when the guide protrusion 20 is provided, an annular recess is formed in the inner peripheral portion of the disk substrate,
In addition to making it difficult to print on the inner peripheral portion of the disk substrate for decoration and the like, it becomes difficult to form a protective film that covers the signal recording portion, and the concave portion causes the innermost peripheral position of the signal recording area, and eventually The problem that the writable information amount is limited is also caused, and it is not always an effective method.

[0006]

The present invention has been made in view of the circumstances as described above, and a problem to be solved by the present invention is to easily and favorably position a stamper with respect to a cavity forming surface of a mold. It is an object of the present invention to provide a novel disk substrate molding die and molding method that can be set with good properties.

[0007]

In order to solve such a problem, a feature of the present invention resides in that a cavity forming surface in at least one of a fixed mold and a movable mold which are mold-molded with each other to form a molding cavity. In a die for molding a disk substrate, in which an annular plate-shaped stamper is mounted, and the inner peripheral portion of the stamper is sucked and held by the cavity forming surface so as to protrude to the central portion of the cavity forming surface. The guide sleeve, in which the central hole of the stamper is fitted to the outer peripheral surface, is provided so as to be capable of reciprocating in the protruding direction.

Further, according to the present invention, when an annular plate-shaped stamper is attached to the cavity forming surface of the mold for molding the disk substrate, and the inner peripheral portion of the stamper is suction-adsorbed to the cavity forming surface and held. (A) a step of positioning the stamper on the cavity forming surface by projecting a guide sleeve in a central portion of the cavity forming surface and fitting a center hole of the stamper to an outer peripheral surface of the guide sleeve; (B) a step of retracting the guide sleeve fitted in the center hole of the stamper so that the protruding tip end surface of the guide sleeve is substantially flush with the surface of the stamper superposed on the cavity forming surface. A method of molding a disk substrate including is also characterized.

[0009]

In the mold for molding the disk substrate having the structure according to the present invention, since the guide sleeve is capable of projecting / retracting, the guide sleeve is placed in the projecting position and largely located on the cavity forming surface. The central hole of the stamper can be fitted to the outer peripheral surface of the guide sleeve in the protruding state, and the guide sleeve can be set in the retracted position to suppress the amount of protrusion of the guide sleeve into the molding cavity. I can.

Therefore, the stamper can be easily and quickly fitted to the guide sleeve, the workability of fitting the stamper to the guide sleeve for positioning the stamper on the cavity forming surface is improved, and a defect is caused. The fitting can be easily visually recognized, and the start of molding with insufficient fitting is prevented, and the stamper is effectively prevented from being damaged.

Moreover, when the molding cavity is filled with the resin material to mold the disk substrate, the guide sleeve is set back so that the front end surface of the guide sleeve is substantially flush with the surface of the stamper. Since this is possible, it is possible to avoid the obstruction of the flow of the filling resin material by the guide sleeve and obtain excellent product quality, and also to avoid forming a recess or the like in the disc substrate that is the product.

Further, according to the method of the present invention, since the guide sleeve is largely projected on the cavity forming surface,
The stamper can be fitted easily, and the guide sleeve is set back when the disk substrate is molded, preventing it from protruding into the molding cavity, thus improving the workability of mounting the stamper as described above. Any of the effects such as improvement of the product quality of the disk substrate and the disk substrate can be effectively exhibited.

[0013]

EXAMPLES Examples of the present invention will now be described in detail in order to further clarify the present invention.

First, FIG. 1 shows a mold for molding an optical disk substrate as an embodiment of the present invention. This mold includes a fixed mold 22 and a movable mold 24, and although not shown, the fixed mold 22 is attached to a fixed plate of the mold clamping device, while the movable mold 24 is attached to the mold clamping device. The movable platen is mounted and supported on the movable platen, and the fixed mold 22 and the movable mold 24 are opened and closed by driving the movable platen toward and away from the fixed platen.
Then, as shown in the drawing, the fixed mold 22 and the movable mold 24 are matched with each other, so that the disk molding cavity 26 is formed between the mold matching surfaces.

More specifically, the fixed mold 22 has a fixed mirror block 28 on the side where the molding cavity 26 is formed, and a center bush 30 is attached and fixed through the central portion of the fixed mirror block 28. The surface of the fixed mirror block 28 and the center bush 30.
The fixed side cavity forming surface 32 is constituted by the axial end surface of the. A sprue bush 34 is fixedly assembled in the center hole of the center bush 30. Through this sprue bush 34, the resin material injected from a nozzle of an injection device (not shown) is passed through the molding cavity 26.
It is designed to be filled by being guided to. Further, a compressed air passage 36 is formed inside the fixed mold 22, and the compressed air guided through the compressed air passage 36 forms a fixed side cavity through a gap between the fixed mirror block 28 and the center bush 30. It is designed to be ejected onto the surface 32. Then, the molding cavity 2 is compressed by the compressed air ejected onto the fixed side cavity forming surface 32.
The optical disk substrate molded in 6 is released from the fixed mold 22 when the mold is opened.

The end face of the sprue bush 34 on the side of the molding cavity 26 is positioned so as to be slightly retracted inward in the axial direction from the end face of the center bush 30 in the axial direction, whereby the molding cavity in the center bush 30 is positioned. A female cutter for punching out the central hole of the optical disk substrate is constituted by the peripheral edge of the opening on the side of 26.

On the other hand, the movable mold 24 is provided with a movable mirror block 38 on the side where the molding cavity 26 is formed, and an outer sleeve 40 is attached and fixed through the central portion of the movable mirror block 38. The movable side cavity forming surface 42 is constituted by the surface of the movable mirror block 38 and the axial end surface of the outer sleeve 40. Then, an annular plate-shaped stamper 44 (see FIG. 3) having minute projections corresponding to information signals on the surface is mounted on the movable side cavity forming surface 42.

Negative pressure air passages 46 and 48 are formed inside the movable mold 24, and the negative pressure suction force exerted through the negative pressure air passage 46 is applied to the movable mirror block 3.
8 through the gap between the outer sleeve 40 and the inner peripheral portion of the stamper 44 set on the movable side cavity forming surface 42, and the negative pressure suction force exerted through the negative pressure air passage 48 is applied. The suction holes 50 formed in the movable mirror block 38 act on the outer peripheral portion of the stamper 44 set on the movable side cavity forming surface 42. The negative pressure suction force exerted through the negative pressure air passages 46 and 48 causes the stamper 44 to be suction-adsorbed on the movable side cavity forming surface 42. A pressing ring 52 having a substantially hook-shaped cross-section is fixed to the outer peripheral edge of the movable mirror block 38, and the pressing ring 52 also causes the outer peripheral edge of the stamper 44 to be on the movable cavity forming surface 42. It is supposed to be restrained.

Further, as shown in an enlarged view in FIG. 2, the outer sleeve 4 is provided at the center of the movable mold 24.
In the inner hole of 0, a protruding sleeve 54, an ejector sleeve 56, a male cutter sleeve 58, and an inner sleeve 60, each of which has a substantially cylindrical shape, are sequentially inserted into each other and arranged so as to be relatively movable in the axial direction. An ejector pin 62 is axially movably inserted into the inner sleeve 60 arranged at the innermost peripheral portion. Projection sleeve 54 and ejector sleeve 56
Is slightly protruded from the movable side cavity forming surface 42 and is opposed to the center bush 30 of the fixed mold 22 with a predetermined distance, and a part of the molding cavity 26 is formed between the opposed surfaces. And the stamper 4 is attached to the outer peripheral surface of the protruding sleeve 54.
The center hole 64 of No. 4 is fitted to the stamper 44 so that the stamper 44 is positioned on the movable side cavity forming surface 42. Further, the male cutter sleeve 58, the inner sleeve 60, and the ejector pin 62 are positioned to face the sprue bush 34 of the fixed mold 22 with a predetermined distance therebetween, and the resin material introduced through the sprue portion between the facing surfaces. Is formed so as to guide the mold to the molding cavity 26.

Then, under the clamped state of the fixed mold 22 and the movable mold 24, the resin material injected through the sprue portion of the sprue bush 34 is filled into the molding cavity 26 through the runner portion, whereby the information of the stamper 44 is obtained. The disk substrate to which the data has been transferred is molded, and the male cutter sleeve 58 is projected and fitted into the inner hole of the center bush 30 after filling the molding cavity 26 with the resin material. While the center hole of the substrate is punched out, the ejector sleeve 56 and the ejector pin 62 are projected after the resin material is cooled and solidified to open the die, so that the molded disc substrate and the sprue runner are released. It is designed to be taken out. The movable mold 24
A compressed air passage 65 is formed inside the compressed air passage 65, and the compressed air introduced through the compressed air passage 65 is ejected to the movable cavity forming surface 42 through the gap between the protruding sleeve 54 and the ejector sleeve 56. The ejection of the compressed air assists the release of the molded disc substrate.

The projecting sleeve 54 is slidable on the outer peripheral surface of the ejector sleeve 56 so as to be relatively movable in the axial direction. Furthermore, the axially inner end portion of the protruding sleeve 54 is a large diameter portion 66 having a large outer diameter over a predetermined axial length, and both axial end surfaces of the large diameter portion 66 are outer. By contacting the sleeve 40 or the support block 68, the protruding sleeve 5
The moving ends on both sides in the axial direction of 4 are defined.

Further, a male screw groove is formed on the outer peripheral surface of the large diameter portion 66 of the protruding sleeve 54, and the large diameter portion 66 constitutes a bolt-shaped portion. Further, a transmission gear 70 having a nut-shaped portion with an internal thread groove formed in the inner peripheral portion and a bevel gear portion in the outer peripheral portion is disposed radially outward of the protruding sleeve 54, and the thrust bearing 72 is provided. And is rotatably supported via a bush 74,
The nut-shaped portion of the transmission gear 70 is screwed onto the bolt-shaped portion of the large diameter portion 66 of the protruding sleeve 54. Further, a bevel gear 76 with a shaft is arranged outside the transmission gear 70, and the shaft portion is supported rotatably around the central axis through thrust bearings 78, 80 and a bush 82. The bevel gear portion of the bevel gear 76 is the transmission gear 70.
Is meshed with the bevel gear portion. The outer tip of the shaft of the bevel gear with shaft 76 extends toward the side surface of the movable mold 24, and the drive handle 84 is attached to this tip.

As a result, when the drive handle 84 is manually rotated, the rotational driving force is changed to a bevel gear 76 with a shaft.
The transmission gear 70 is caused to rotate via the transmission gear 70, and the nut-shaped portion of the transmission gear 70 and the bolt-shaped portion of the projecting sleeve 54 are screw-fed.
The projecting sleeve 54 is adapted to be projected / retracted in the axial direction. At the protruding position of the protruding sleeve 54, which is defined by the contact of the large-diameter portion 66 with the outer sleeve 40, as shown in FIG. On the other hand, in the retracted position of the protruding sleeve 54, which is defined by the contact of the large diameter portion 66 with the support block 68, as shown in FIG. 3, the distal end surface of the protruding sleeve 54 is movable. The amount of protrusion from the side cavity forming surface 42 is reduced. Even when the protruding sleeve 54 is moved backward, the fitted state of the stamper 44 with respect to the outer peripheral surface of the protruding sleeve 54 is maintained, and the positioning function of the stamper 44 by the protruding sleeve 54 can be effectively exerted. It has become.

Further, particularly in the present embodiment, it is preferable that h1 = 1 so that the protruding amount h1 (see FIG. 2) of the protruding sleeve 54 at the protruding position is sufficiently larger than the thickness of the stamper 44 to be mounted. The protrusion amount of the protrusion sleeve 54 at the retracted position is set to about 5 mm and is h2.
(See FIG. 3) is generally set to about h2 = 0.3 mm so that the thickness is the same as or substantially the same as the thickness of the stamper 44 to be mounted. Further, as shown in FIG. 3, in the present embodiment, the protruding tip surface of the ejector sleeve 56 is also in the retracted position, and the protruding sleeve 54 is in the retracted position.
Is substantially flush with the tip surface of the.

When molding an optical disk substrate using the molding die having such a structure, for example, when the stamper 44 is set at a predetermined position on the movable side cavity forming surface 42, it is shown in FIG. Rotating bevel gear 76 with drive handle 84 so that protruding sleeve 5
4 is set in the protruding position, the central hole 64 of the stamper 44 is fitted to the outer peripheral surface of the protruding sleeve 54, and then the stamper 44 is pushed in the axial direction to move the stamper 44 to the movable cavity forming surface. 42 Lead it on and set it. Also, the negative pressure air passages 46, 4 of the movable mold 24 are
By connecting 8 to a negative pressure source, a suction force is exerted on the stamper 44 superposed on the movable side cavity forming surface 42 so that the stamper 44 is sucked and held on the movable side cavity forming surface 42.

After that, the bevel gear 76 with a shaft is rotated by the drive handle 84 to move the protruding sleeve 54 to the retracted position, and as shown in FIG.
The protruding sleeve 54 fitted in the central hole 64 of
The tip end surface is retracted until it becomes flush or substantially flush with the surface of the stamper 44. Then, after that, the fixed mold 22 is fitted and clamped to the movable mold 24, and both molds 24, 2 are
A molding substrate 26 is molded by forming a molding cavity 26 between the two and injecting and filling a predetermined resin material into the molding cavity 26.

Therefore, when the optical disk substrate is molded by using the molding die having the above-mentioned structure, when the stamper 44 is fitted to the protruding sleeve 54 and the positioning is set on the movable side cavity forming surface 42, the protruding sleeve is formed. Since 54 is largely protruded from the movable side cavity forming surface 42, it is possible to easily fit the stamper 44 to the protruding sleeve 54, and
It is possible to easily visually confirm whether or not the stamper 44 is securely fitted to the protruding sleeve 54, and the stamper 44 can be set with good workability and excellent reliability. .

Moreover, when the resin material is injected and filled, the protruding sleeve 54 is retracted so as to be substantially flush with the surface of the stamper 44, thereby preventing the protruding sleeve 54 from protruding into the molding cavity 26. Therefore, the fluidity of the filled resin material is not obstructed by the protruding sleeve 54, and the quality deterioration such as birefringence due to the obstruction of the fluidity of the resin material or the like is prevented, and the optical disc substrate as a product is prevented. The quality and its stability can be advantageously ensured.

Further, the backward movement of the protruding sleeve 54 prevents the protruding sleeve 54 from protruding into the molding cavity 26, so that a recess or the like may be formed in the optical disk substrate by the protruding sleeve 54. Without
Since the inner peripheral portion of the optical disc substrate is formed with a smooth surface, product defects such as warpage of the product due to the formation of the recess are prevented, and printing and signal recording of the disc substrate are prevented. The area for this can be advantageously secured to the inner peripheral side.

Although the embodiments of the present invention have been described in detail, these are literal examples, and the present invention is not construed as being limited to such specific examples.

For example, the mechanism for axially projecting / retracting the guide sleeve 54 need not be the screw feed mechanism as illustrated, but the guide sleeve 54 may be axially projected / removed by a rack and pinion mechanism or a cam mechanism. It is also possible to operate it in reverse.

Further, the driving means of the guide sleeve 54 does not have to be a gear driving means by human power as illustrated, but an electric driving means, a hydraulic driving means or the like can be adopted.

Further, the guide sleeve 54 can constitute an ejector mechanism for releasing the molded disk substrate.

In the above embodiment, the stamper 44 is mounted on the movable mold 24 side, but instead of or in addition to this, the stamper is mounted on the fixed mold 22 side. The present invention can be similarly applied to the molded molds.

Furthermore, in the above embodiment, one specific example of the molding die for the optical disk substrate having the structure according to the present invention has been described, but the present invention is similarly applied to the molding die for the magneto-optical disk substrate. Of course, it is applicable.

Further, in the above embodiment, the stamper 44 is sucked and adsorbed by the negative pressure air with respect to the movable side cavity forming surface 42. However, the stamper can be moved by a magnetic force using an electromagnet or the like. It may be sucked and adsorbed on the side cavity forming surface.

Further, in the above embodiment, the guide sleeve 5
Although the stamper 44 fitted to the outer peripheral surface of the guide sleeve 54 is pushed in the axial direction and set on the movable side cavity forming surface 42 at the protruding position of No. 4, the stamper at the protruding position of the guide sleeve 54 is described. 44
After fitting the guide sleeve 54 to the retracted position, the stamper 44 moves the guide sleeve 54 to the guide sleeve 54.
It is not necessary to push the stamper 44 in the axial direction before the backward movement of the guide sleeve 54 since the guide sleeve 54 is guided and set on the movable side cavity forming surface 42.

In addition, although not enumerated one by one, the present invention
Based on the knowledge of those skilled in the art, it can be implemented in various modified, modified, and improved modes, and
It goes without saying that all such embodiments are included within the scope of the present invention, without departing from the spirit of the present invention.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a schematic structure of a molding die for an optical disc substrate as an embodiment of the present invention.

2 is a cross-sectional explanatory view showing an enlarged main part of a movable mold in order to explain one step of a molding operation using the molding die shown in FIG. 1. FIG.

FIG. 3 is a cross-sectional explanatory view showing an enlarged main part of a movable mold in order to explain another step of a molding operation using the molding die shown in FIG.

FIG. 4 is a cross-sectional explanatory view schematically showing a mold for molding a disk substrate having a conventional structure which is the basis of the present invention.

FIG. 5 is a cross-sectional explanatory view schematically showing another example of the structure of the disk substrate molding die which is the basis of the present invention.

[Explanation of symbols]

 22 Fixed Mold 24 Movable Mold 26 Disc Molding Cavity 32 Fixed Side Cavity Forming Surface 42 Movable Side Cavity Forming Surface 44 Stampers 46, 48 Negative Pressure Air Passage 54 Projecting Sleeve 64 Center Hole 70 Transmission Gear 76 Shaft Bevel Gear 84 Drive Handle

Claims (2)

[Claims] 1. An annular plate-shaped stamper is attached to a cavity forming surface of at least one of a fixed die and a movable die which are fitted to each other to form a forming cavity, and an inner peripheral portion of the stamper is attached to the cavity forming surface. In a mold for molding a disk substrate, which is adapted to be sucked and held by the cavity forming surface, the mold is made to protrude in a central portion of the cavity forming surface,
A mold for molding a disk substrate, characterized in that a guide sleeve in which the center hole of the stamper is fitted to the outer peripheral surface is provided so as to be capable of reciprocating in the protruding direction. 2. A cavity forming surface when a ring-shaped plate-shaped stamper is attached to a cavity forming surface of a mold for molding a disk substrate and the inner peripheral portion of the stamper is suction-adsorbed to and held by the cavity forming surface. Positioning the stamper on the cavity forming surface by protruding the guide sleeve to the central portion of the guide sleeve and fitting the center hole of the stamper to the outer peripheral surface of the guide sleeve; And retreating the combined guide sleeve so that the protruding tip end surface of the guide sleeve is flush with or substantially flush with the surface of the stamper that is superposed on the cavity forming surface. Disk substrate molding method.