JPH10247341A - Metal mold for molding disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To a stamper having a central hole of a small diameter settable, and to make the disk surface have a flat surface to be adequate for bonding over a wide range, by using a sprue bushing having a stepped surface as a female cutter on the front end face in the axial direction and disposing a stamper retaining sleeve directly on the outer peripheral surface thereof. SOLUTION: The stepped surface 66 is formed as the female cutter on the front end in the axial direction of the sprue bushing 38 and the stamper retaining sleeve 40 is directly mounted onto the outer peripheral surface of the sprue bushing 38. When the stamper retaining sleeve 40 is going to be formed to a smaller diameter, only the sprue bushing 38 exists on the inner side thereof and further the stepped surface 66 as the female cutter exists at its front end and, therefore, the sleeve 40 is formable to the smaller diameter without reducing the thicknesses of the inner and outer sleeves 44, 46 and the molding of the disk substrate with the small stamper 74 of a bore size diameter ϕb is made possible. As a result, the setting of the inner side in the radial direction in the position of the recessed groove formed on the front surface of the disk substrate is made possible by the retaining pawls 72 of the sleeve 40 is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk molding die for forming a synthetic resin optical disk substrate on which information of the stamper is transferred by using a stamper on which predetermined information is engraved. The present invention relates to a disk forming die suitable for forming a disk substrate or the like for a picture disk or a laminated disk.

[0002]

2. Description of the Related Art Optical disks (including magneto-optical disks)
It is used in a wide range of applications such as audio, video, and computers, but in its manufacture, it is used to mold a disk consisting of a fixed mold and a movable mold that form a cavity for molding a disk by being matched with each other. Using a mold, set an annular plate-shaped stamper on the cavity forming surface of the fixed mold, fill the cavity with resin material, and transfer information such as pits and pregrooves carved on the stamper surface. Disc substrate is used. By the way, in the conventional mold, generally, in order to hold the stamper on the cavity forming surface of the fixed mold, a stamper holding sleeve is detachably inserted into the outer peripheral side of the sprue bush attached to the center of the fixed mold. The stamper pressing sleeve is fixed, and the inner peripheral edge of the stamper is held down by an annular claw projecting from the axial end of the stamper holding sleeve.

However, since the inner diameter of the stamper is generally set to be larger than the inner diameter of the optical disk by a predetermined amount, the use of such a stamper pressing sleeve makes it possible to hold the inner peripheral edge of the stamper. Since the claw portion of the sleeve is positioned so as to slightly protrude into the disc molding cavity, it is inevitable that an annular groove is formed by the claw portion on the surface of the optical disk. Existence has become a problem. That is, in recent years, a super picture disk printed on almost the entire surface of a disk has been proposed for the purpose of improving commercial value by a design effect, etc., but printing on a groove formed on the disk surface is extremely difficult. In addition, the existence of the concave groove is a problem. In addition, in the case of a bonded disc such as a DVD, generally, after applying an adhesive to the inner peripheral edge of the bonded surface of the disk substrate, the disk substrate is rotated by a spin coater and the adhesive is applied to the entire surface of the bonded surface by centrifugal force. Spread,
Although the two disk substrates are bonded together, if there is a groove on the disk surface, the adhesive will be scattered by the groove when rotated by a spin coater, and it will be easy for adhesive failure to occur, The existence of the groove is a problem.

Therefore, in order to cope with such a problem, it is conceivable to make the center hole of the stamper small so that the surface of the disk substrate is made flat over substantially the entire surface. Specifically, when the central hole diameter of the disk substrate is φ15 mm, flattening over substantially the entire surface of the disk substrate surface can be advantageously achieved by employing a stamper having a central hole diameter of 23 mm or less. Become. However, in a conventional mold, it was extremely difficult to employ a stamper having such a small diameter in the center hole.

That is, in order to mount a stamper having a small diameter in the center hole, the diameter of the stamper holding sleeve must be reduced. However, a male that is driven to protrude from the movable mold side inward in the radial direction of the stamper holding sleeve. A female cutter sleeve constituted by the inner peripheral surface of the distal end portion is provided with a female cutter for punching a center hole of the disc substrate in cooperation with the cutter, and a mold cutter is provided between the stamper holding sleeve and the female cutter sleeve. Since it is necessary to form a gap for air blow, there is a problem that if the diameter of the stamper holding sleeve is reduced, the member strength and workability of the stamper holding sleeve and the female cutter sleeve cannot be sufficiently secured.

[0006] Instead of using a stamper holding sleeve, as described in Japanese Patent Application Laid-Open No. 5-185475, a positioning projection that fits into a center hole of a stamper at a central portion of a cavity forming surface of a fixed mold. In addition to forming the air suction passage opening in the cavity forming surface and applying a negative pressure suction force to the inner peripheral edge of the stamper positioned by the positioning projection, the stamper can be suction-held on the cavity forming surface. It is possible,
In a mold having such a structure, since there is no claw portion that covers the inner peripheral edge of the stamper from the surface side, the resin material enters the gap between the center hole of the stamper and the positioning protrusion during the molding of the disc substrate. Thus, there is a problem that defects such as burrs are likely to occur.

[0007]

The present invention has been made in view of the circumstances described above, and an object of the present invention is to set a stamper having a small diameter in the center hole. In addition, the occurrence of burrs on the disk substrate is also prevented, and a disk molding die having an improved structure capable of advantageously forming a disk substrate of high commercial value having a flat surface over a wide area can be advantageously formed. Is to provide.

Further, according to the present invention, the strength and manufacturability of each member are sufficiently ensured, and a gap for air blow for releasing the disk substrate is advantageously formed, so that excellent release properties can be obtained. It is another object of the present invention to provide a disk molding die having an improved structure capable of stably forming a disk substrate of good quality.

[0009]

In order to solve such a problem, the present invention according to claim 1 comprises a fixed mold and a movable mold which form a disk molding cavity by being mutually matched, An inner peripheral edge of an annular plate-shaped stamper that is removably inserted and fixed on the outer peripheral side of the sprue bush assembled to the center of the fixed mold and is superposed on the cavity forming surface of the fixed mold. Is formed by an annular claw projecting from the stamper holding sleeve, and the center of the axial end surface of the sprue bush is recessed to form an annular step surface. A female cutter for punching a disc center hole in cooperation with a male cutter driven to be driven from the movable mold side, and an outer peripheral surface of the sprue bush. And allowed extrapolation placing the stamper holder sleeve directly, between fitting 挿面 thereof sprue bush and the stamper holding sleeve, that the formation of the air blow gap opening into the disc molding cavity, and its features.

[0010] In the disk molding die having the structure according to the first aspect of the present invention, a special sprue bush structure in which the sprue bush and the female cutter sleeve are integrally formed is employed, thereby increasing the strength of the member. It is possible to use a stamper holding sleeve with a small diameter while avoiding problems such as deterioration of productivity and the like, so that a stamper with a small diameter in the center hole can be set, and the surface can be widened. A disk substrate of high commercial value having a flat surface over the entire surface can be advantageously formed while preventing defects such as burrs from occurring.

In addition, in such a disk molding die, since a gap for air blow is formed between the stamper holding sleeve and the insertion surface of the sprue bush, it is possible to take out a molded product of the disk substrate with a stable release property. As a result, the occurrence of defects due to uneven release can be prevented, and the quality of the disk substrate molded product can be advantageously stabilized.

The invention described in claim 2 is the first invention.
Wherein the sprue bush comprises an inner sleeve having a sprue hole on a central axis, and an outer sleeve having the annular step surface on an axial end face. The outer sleeve is directly fitted to and fixed to the inner sleeve, and a temperature control fluid flow passage is formed between the fitting surfaces of the inner sleeve and the outer sleeve. That is the feature.

That is, in the disk molding die having the structure according to the first aspect of the present invention, the sprue bush having the special structure as described above can be formed by a single component. In the disk molding die having the structure according to the second aspect of the present invention, since the sprue bush is configured with a divided structure including the inner sleeve and the outer sleeve, the temperature of the resin material injected through the sprue hole is maintained. A flow path for the conditioning fluid can be advantageously formed.

[0014] The invention according to claim 3 provides the invention according to claim 1.
Alternatively, in the disk molding die having the structure according to the invention described in 2, the outer diameter of the stamper holding sleeve is 23 mm or less.

The disk molding die having the structure according to the third aspect of the present invention is preferably used for molding a disk substrate for a CD or a DVD, whereby the surface excluding the inner peripheral edge portion is removed. This makes it possible to advantageously form a disk substrate which is flat over the entire surface and which is suitably employed as a substrate for a super picture disk or a bonded disk.

The invention described in claim 4 is the first invention.
4. A disk molding die having a structure according to any one of the above-described aspects, wherein the outer peripheral surface of the stamper holding sleeve gradually moves from the side where the annular claw portion is formed to the other side in the axial direction. It is characterized in that a tapered surface with a reduced diameter is formed.

In the disk molding die having the structure according to the fourth aspect of the present invention, the operation of mounting the stamper holding sleeve on the fixing die and the operation of mounting the stamper on the stamper holding sleeve are facilitated.
The workability of setting and replacing the stamper can be improved, and the positioning using the tapered surface allows the positioning accuracy of the stamper holding sleeve with respect to the fixing die,
As a result, the positioning accuracy of the stamper with respect to the fixed mold can be improved.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, in order to clarify the present invention more specifically, one embodiment of the present invention will be described in detail with reference to the drawings.

First, FIG. 1 is a sectional view of a main part of a mold for molding an optical disk substrate according to an embodiment of the present invention. Such a molding die includes a movable die 10 and a fixed die 12 attached to a movable plate and a fixed plate, respectively, of a mold clamping device (not shown), and the fixed plate of the mold clamping device is driven with respect to the movable plate. As a result, the movable mold 10 is displaced in the approaching / separating direction with respect to the fixed mold 12, and the mold opening / closing operation is performed. When the movable mold 10 and the fixed mold 12 are closed, a molding cavity 14 of the disk substrate is defined between the mold matching surfaces.

More specifically, the movable mold 10 is provided with a movable mirror block 16 on the surface on which the molding cavity 14 is formed, and a large-diameter axial through hole 18 is formed in the center of the movable mirror block 16. Have been. Also, an ejector pin 20 having a circular rod shape and a guide sleeve 22, a male cutter sleeve 24, and an ejector sleeve 2 each having a substantially cylindrical shape are filled in the through hole 18.
The mirror sleeve 6 and the mirror surface sleeve 28 are sequentially inserted in the through hole 18 in a state where the mirror sleeve 6 and the mirror sleeve 28 are overlapped in the radial direction and inserted inside and outside.

Then, the mirror surface of the movable mirror block 16 and the axial end surfaces of the mirror surface sleeve 28 and the ejector sleeve 26 cooperate with a movable cavity surface 30 defining the molding cavity 14 with the fixed mold 12. It is formed by working. A sprue 32 is formed between the ejector pin 20, the guide sleeve 22, and the fixed cutter 12 by the axial end surfaces of the male cutter sleeve 24. Furthermore, male cutter sleeve 24
Is driven in the axial direction toward the fixed mold 12 after filling the molding cavity 14 with the resin material, so that the center hole of the disk substrate is punched and formed in cooperation with the female cutter described later. And movable mold 1
After the mold 0 and the fixed mold 12 are opened, the ejector pin 20 and the ejector sleeve 26 are driven to protrude in the axial direction toward the fixed mold 12, so that the sprue and the disc substrate are separated from the movable mold 10, respectively. Is to be typed.

On the other hand, the fixed mold 12 is
4 is provided with a fixed mirror block 34 on the forming surface side.
An axial through-hole 36 is formed in a central portion of the fixed mirror block 34. A sprue bush 38 having a sprue hole 37 for injecting and filling the molding cavity 14 with a resin material is fixedly inserted and disposed at the center of the through hole 36, and is provided on the outer peripheral surface of the sprue bush 38. A stamper holding sleeve 40 having a substantially cylindrical shape is externally provided, and the sprue bush 38 and the stamper holding sleeve 40 fill the through hole 36 in the fixed mold 12. The mirror surface of the fixed mirror block 34 and the outer peripheral portions of the axial end surface of the stamper holding sleeve 40 and the axial end surface of the sprue bush 38 cooperate to form a fixed cavity surface 42 that defines the molding cavity 14. ing. The sprue 32 is formed between the movable mold 10 and the inner peripheral portion of the axial end surface of the sprue bush 38.

As shown in FIG. 2, the sprue bush 38 is formed by fitting an outer sleeve 46 to an inner sleeve 44 having a sprue hole 37. Inner sleeve 44
Is a large-diameter portion 50 in which a recess 48 for nozzle touch is formed.
And a small-diameter portion 52 formed with a sprue hole 37 extending gradually from the bottom of the recess 48 toward the other end surface in the axial direction on the central axis. At the outer peripheral edge of the large-diameter portion 50, it is bolted to a mounting plate 54 to which the fixed mirror block 34 is mounted. A substantially annular plate-shaped locate ring 56 is superposed and fixed to the axial end face of the inner sleeve 44 on the large diameter bracket 50 side.

On the other hand, the outer sleeve 46 has a substantially cylindrical shape, and an annular plate-shaped contact portion 58 protruding outward in the radial direction is integrally formed at one end in the axial direction. ing. The outer sleeve 46 is externally inserted into the small-diameter portion 52 of the inner sleeve 44, and the abutting portion 58 is brought into contact with the step surface 60 of the inner sleeve 44 to be positioned in the axial direction. Is fixed to

The outer sleeve 46 and the inner sleeve 4
An annular channel 62 extending continuously in the circumferential direction between the two cylindrical wall portions is formed between the fitting surfaces of No. 4 and a temperature adjusting fluid such as water circulated through a supply / discharge channel (not shown). The temperature of the resin material supplied through the sprue bush 38 and the sprue hole 37 can be adjusted by flowing through the annular flow path 62. In addition, between the fitting surfaces of the outer sleeve 46 and the inner sleeve 44, on both sides of the annular flow path 62 in the axial direction,
Seal members 64 and 64 are provided, respectively, to ensure fluid tightness to the outer space of the annular flow path 62.

Further, an annular step surface 66 is formed on the axial end surface of the outer sleeve 46 on the molding cavity 14 side so as to extend continuously in the circumferential direction at a radially intermediate portion. The inner peripheral side is formed as a concave portion 68 which is dented in the axial direction with respect to the outer peripheral side. The axial end face of the inner sleeve 44 is
Are in the same plane as the axial end surface of the recess 68. In other words, an annular protrusion 70 protruding in the axial direction at the outer peripheral edge is integrally formed on the axial end surface of the outer sleeve 46, and the stepped surface 66 is formed by the inner peripheral surface of the annular protrusion 70.
Is configured.

The diameter of the stepped surface 66: φa
Is set in accordance with the outer diameter of the male cutter sleeve 24 of the movable mold 10, so that the step surface 66
Constitutes a female cutter. As a result, the male cutter sleeve 24 of the movable mold 10 is caused to protrude and protrude toward the recess 68 of the sprue bush 38 so that a center hole of the disk substrate is punched out. .

Further, on the outer peripheral surface of such a sprue bush 38, a stamper holding sleeve 40 is mounted by being directly extrapolated. This stamper holding sleeve 4
0 has a substantially cylindrical shape as a whole, and is detachably inserted into a space between the sprue bush 38 and the fixed mirror block 34 from the fixed-side cavity surface 42 side in the axial direction. It is assembled. And
One end face of the stamper holding sleeve 40 in the axial direction has a contact portion 5 of the outer sleeve 46 of the sprue bush 38.
8, the other end surface in the axial direction is positioned in the axial direction with the end surface of the annular protrusion 70 of the outer sleeve 46 of the sprue bush 38 being flush with the end surface. .

Although not apparent in the drawings, an air passage extending in the axial direction is provided between the sprue bush 38 and the insertion surface of the stamper holding sleeve 40 at a predetermined distance in the circumferential direction. It is formed continuously in the direction. Compressed air guided through a supply passage (not shown) passes through the air passage and passes through the fixed-side cavity surface 4.
When the mold is opened after molding the disk substrate in the molding cavity 14, the compressed disk substrate is separated from the fixed mold 12 by ejecting compressed air. The type is to be assisted.

Further, an annular pressing claw 72 slightly projecting in the axial direction from the outer peripheral edge and extending outward in the radial direction is integrally formed at one end in the axial direction of the stamper pressing sleeve 40 (the end on the molding cavity 14 side). Is formed. Then, after a thin annular plate-shaped stamper 74 on which predetermined information such as pits is engraved is superimposed on the surface (cavity forming surface) of the fixed mirror block 34, the stamper holding sleeve 40 is fixed to the fixed mold 12. The stamper 7
4 is positioned outside the stamper holding sleeve 40 and positioned, and the inner peripheral edge of the stamper 74 is pressed from the outside by the holding claws 72 of the stamper holding sleeve 40, and is held on the fixed side cavity surface 42. It has become. In addition, on the outer peripheral edge of the fixed mirror block 34,
A stamper holding ring 75 is fixed, and the outer peripheral edge of the stamper 74 is held on the mirror surface of the fixed mirror block 34 by the stamper holding ring 75.

The outer diameter of the stamper holding sleeve 40 is slightly smaller than the center hole diameter: φb of the stamper 74 at the axial end on the side of the holding claw 72, and fitted into the center hole of the stamper 74. And the presser claw 7
A tapered outer peripheral surface 76 whose diameter gradually decreases from the two axial ends toward the other axial side is formed with a predetermined length. The tapered outer peripheral surface 76 facilitates the work of inserting the stamper holding sleeve 40 into the space between the sprue bush 38 and the fixed mirror block 34, and the positioning accuracy of the stamper holding sleeve 40 with respect to the fixed mirror block 34. Is being improved.

Further, the front end of the stamper holding sleeve 40 in the insertion direction with respect to the fixed mold 12 (the right end in the figure).
Is a worm portion 78 having a thread groove extending in the circumferential direction on the outer peripheral surface over a predetermined length, and a key groove extending in the axial direction is formed in the worm portion 78. And the stamper holding sleeve 40 is fixed mold 1
2, when fixed to the keyway,
The key protrusion 80 fixed to the stamper is engaged, so that the rotation of the stamper holding sleeve 40 around the central axis is prevented, and only the axial displacement is allowed. Further, an annular transmission gear 84 which is disposed on the outer peripheral side of the sprue bush 38 and is driven to rotate about the central axis by a manual rotary shaft 82 is meshed with the worm portion 78. After inserting the sleeve 40 into the fixed mold 12,
By rotating the manual rotary shaft 82, the rotational force is exerted on the stamper holding sleeve 40 via the transmission gear 84, whereby the stamper holding sleeve 40 is guided and held at a predetermined position by the screw feed action. It has become so.

In the molding die having the above-described structure, a female cutter is formed by the annular stepped surface 66 formed on the axial end surface of the sprue bush 38. Since the stamper holding sleeve 40 is directly mounted on the outside of the stamper holding sleeve 40, even when the diameter of the stamper holding sleeve 40 is reduced,
Significant thinning of the member disposed inside the stamper holding sleeve 40 is avoided. In other words, what is disposed radially inside the stamper holding sleeve 40 is
There is only the sprue bush 38, and at the radially intermediate portion of the axial end surface of the sprue bush 38,
Since the stepped surface 66 constituting the female cutter is formed, the thickness of the inner and outer sleeves 44 and 46 constituting the sprue bush 38 is not reduced so as to be a problem in strength and manufacturability. The inner and outer diameters of the stamper holding sleeve 40 can be set small.

Therefore, it is possible to form the disk substrate by employing the small stamper 74 having the inner diameter dimension: φb, whereby the stamper holding sleeve 4 is formed.
The position of the concave groove formed on the surface of the disk substrate by the zero pressing claw 72 can be set as radially inward as possible. That is, if the disk substrate is molded using such a molding die, at the inner peripheral edge of the disk substrate,
At a portion corresponding to an annular portion having a width: c located on the inner peripheral side of the concave groove formed by the pressing claws 72 of the stamper holding sleeve 40, it is difficult to apply an adhesive by printing or spin coating. By employing the stamper holding sleeve 40 having a small diameter, the size of the portion can be sufficiently reduced so as not to cause a problem.

Specifically, if the molding die of the present embodiment is employed, for example, when forming a super picture disc having a center hole diameter (φa) of 15 mm, the center hole diameter (φb)
It is possible to use a stamper with a diameter of 22 mm, whereby the whole surface on the outer peripheral side from the diameter of 23 mm is flat except for a part of the outer diameter of the pressing claw 72 of the stamper holding sleeve 40 which is slightly less than approximately 23 mm. A substrate for a super-picture disk with a printable surface can be advantageously formed.

Therefore, by using the molding die as described above, it is possible to advantageously produce a disk substrate having a high commercial value, which is suitably used for a super picture disk or a laminated disk. A passage for air blow is also formed between the press sleeve 40 and the sprue bush 38 insertion surface, so that good releasability of the molded product is ensured, and the quality is stabilized.

Moreover, in this molding die, since the inner peripheral edge of the stamper 74 is covered with the pressing claws 72 of the stamper pressing sleeve 40, burrs and the like caused by the intrusion of the resin material into the center hole of the stamper 74 are prevented. The occurrence of defects is also advantageously prevented.

Although the embodiment of the present invention has been described in detail above, this is a literal example, and the present invention is not limited to such a specific example.

For example, the stamper holding sleeve only needs to be detachably attached to the fixed mold. Various attachments such as an air suction mechanism and a locking mechanism in addition to the feed screw mechanism as illustrated. A mechanism can be employed.

Further, the structure on the movable mold side employed in the present invention and the holding structure on the outer peripheral side of the stamper in the fixed mold are not limited at all, and various known structures may be used. It can be adopted as appropriate.

In addition, although not enumerated one by one, the present invention
Based on the knowledge of those skilled in the art, various changes, modifications, improvements, and the like can be made, and unless such embodiments depart from the spirit of the present invention.
Both are included in the scope of the present invention,
Needless to say.

[0042]

As is apparent from the above description, in the disk molding dies having the structures according to the first to fourth aspects of the present invention, all of the step surfaces as female cutters are provided at the axial end surfaces. By adopting a sprue bush with a special structure equipped with a stamper holding sleeve directly on the outer peripheral surface of the sprue bush, a small diameter stamper holding sleeve was adopted, and the central hole was made small in diameter. This makes it possible to set the stamper in an advantageous manner. Therefore, a wide area of the disk surface is made a flat surface, and a disk substrate of high commercial value that is suitably used for a super picture disk, a laminated disk, and the like. Can be advantageously produced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a main part of a disk molding die as an embodiment of the present invention.

FIG. 2 is an enlarged longitudinal sectional view showing a part of a fixed die 12 constituting the disk forming die shown in FIG.

[Explanation of symbols]

 Reference Signs List 10 movable mold 12 fixed mold 14 molding cavity 24 male cutter sleeve 30 movable cavity surface 38 sprue bush 40 stamper holding sleeve 42 fixed cavity surface 66 step surface 72 holding claw 74 stamper

Claims (4)

[Claims] 1. A fixed die and a movable die which form a disk molding cavity by being matched with each other, and a stamper holding sleeve is provided on the outer peripheral side of a sprue bush attached to the center of the fixed die. The stamper is removably inserted and fixed, and the inner peripheral edge of the annular plate-shaped stamper superposed on the cavity forming surface of the fixed mold is held by an annular claw projecting from the stamper holding sleeve. In the disk molding die, the central part of the axial end surface of the sprue bush is recessed to form an annular step surface, so that the disk center cooperates with the male cutter driven to be driven from the movable die side. A female cutter for punching a hole is formed, and the stamper holding sleeve is directly extrapolated and arranged on the outer peripheral surface of the sprue bush. Between fitting 挿面 of Mesh and stamper holder sleeve, the disk molding mold, characterized in that the formation of the air blow gap opening into the disc molding cavity. 2. The sprue bush comprises an inner sleeve having a sprue hole on a central axis and an outer sleeve having an annular step surface on an axial end face, and the outer sleeve is directly fitted on the inner sleeve. 2. The disk forming die according to claim 1, wherein the die is formed and fixed, and a flow path of a temperature adjusting fluid is formed between the fitting surfaces of the inner sleeve and the outer sleeve. 3. The disk molding die according to claim 1, wherein an outer diameter of the stamper holding sleeve is φ23 mm or less. 4. The outer peripheral surface of the stamper holding sleeve is formed with a tapered surface that gradually decreases in diameter from the side where the annular claw portion is formed to the other side in the axial direction. 2. The disk molding die according to 1.