JPH10166400A - Mold for molding disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To advantageously realize an engaging mechanism leaving and holding a disk substrate on the side of a movable mold at the time of mold opening in a simple structure by utilizing a stack rib forming part. SOLUTION: An optical disk substrate 33 is advantageously left and held on the side of a movable mold 12 until mold opening is completed at a time of mold opening after the molding of the optical disk substrate 33 by the engaging action of a stack rib 54 on a molding recessed place 52. Especially, at the time of mold opening, compressed air of the cavity forming surface 22 of a fixed mold 10 is jetted to positively release the optical disk substrate 33 from the fixed mold 10. By allowing suction force to act on the optical disk substrate 33 by the negative pressure suction from the cavity forming surface 42 of the movable mold 12, the optical disk substrate 33 is held on the side of the movable mold 12 still more advantageously.

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 disk substrate on which pits, pre-grooves and the like are formed by transfer of a stamper, and more particularly, to holding a disk substrate on a movable die side when opening the die. At least,
The present invention relates to a disk molding die having a structure in which a removal mechanism provided on a movable mold side releases the mold and removes the mold.

[0002]

2. Description of the Related Art Optical disks (including magneto-optical disks)
Although it has been used as an information recording medium in a wide range of fields, its disk base is formed by filling a predetermined resin material into a molding cavity formed by matching a fixed mold and a movable mold to form a disc. At the same time
It is manufactured by transferring irregularities of a stamper mounted on a cavity forming surface to a disk surface. Then, the disk base thus formed is opened from the fixed die and the movable die, and then released from the molding die by releasing it with a take-out mechanism such as a mechanical ejector or an air blow.

[0003] By the way, a take-out mechanism such as a mechanical ejector is generally provided on the movable die side for reasons such as the structure of the die.
It remains on the cavity forming surface of the movable mold and is held,
After the mold opening is completed, the mold is released from the movable mold and taken out by the removal mechanism. Therefore, when opening the mold, it is necessary to securely hold the disk base against the cavity forming surface on the movable mold side.

However, in the mold having the conventional structure, when the mold is opened after the disc is formed, the disc base remains on the cavity forming surface on the fixed mold side, or separates from the mold during the mold opening and drops. In some cases, there is a problem that continuous molding of the disk cannot be performed due to such a trouble.

In particular, since the releasability of the disk substrate from the stamper is not constant depending on the type of the stamper, molding conditions, and the like, when the mold is opened, air blowing is performed on the cavity forming surface of the fixed die to apply a releasing force to the disk substrate. Even if it did, it was difficult to reliably and stably transfer the disk base to the movable die side and hold it.

[0006]

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to solve the problem by moving a disk base to a movable mold cavity forming surface when opening a mold. A disk molding die with excellent continuous moldability of the disk base, which can be securely moved and held, and after the mold is opened, the disk base can be removed stably by the removal mechanism provided on the movable die side. Is to provide.

[0007]

In order to solve such a problem, a feature of the invention according to claim 1 is that the invention includes a fixed mold and a movable mold that form a molding cavity by being mold-matched to each other. In addition, a take-out mechanism for releasing the disk base formed by the molding cavity by releasing the mold after opening the mold, the disk forming mold provided on the movable mold side, and a removing mechanism with respect to the cavity forming surface of the movable mold. A molding recess is formed on one surface of the disc base to form a protruding circumferentially extending stack rib, and at least one inner surface on the inner peripheral side and the outer peripheral side of the molding recess is opened when the mold is opened. A disk molding die having a locking surface for exerting a locking force on a disk base in a releasing direction.

According to the first aspect of the present invention, the disk base extends in the circumferential direction on the surface of the inner peripheral portion of the disk base, which is conventionally employed for stacking and stocking the manufactured disk bases. By paying attention to the protruding stack ribs in this way, by actively using the formed portions of the stack ribs, an effective locking force for retaining and retaining the disk base on the movable mold side is provided. This constitutes a locking surface that can be exerted.

That is, the stack rib is conventionally formed on the inner peripheral side of the signal recording area on the disk base and has a mountain-shaped cross section having a slight inclination angle with respect to the disk surface. In the described invention, by utilizing the stack rib, a mechanical or physical locking force is applied to the movable die in a disk base whose shape and structure are significantly restricted due to manufacturing, standard or other reasons. Is advantageously realized with a simple structure, whereby the stabilization of the molding of the disc base can be advantageously achieved.

In addition, since the stack rib is formed at a position deviating from the signal recording area, when forming the locking surface by using the formed portion of the stack rib, the stack rib is formed due to a shape change of the stack rib. The change in resin flow does not significantly affect the signal recording characteristics of the disk substrate, and the performance of the disk substrate can be advantageously secured.

Further, in the first aspect of the present invention, the specific shape and structure of the locking surface are not particularly limited. Various shapes and structures can be adopted. More specifically, as in the invention described in claim 2, the inner surface on the outer peripheral side of the molding recess has an inclination angle of 1 to 5 degrees with respect to the release direction of the fixed mold and the movable mold. The structure of the locking surface formed by having an undercut shape or the inner surface on the inner peripheral side of the molding recess as in the invention described in claim 3, wherein the fixed die and the movable die are formed. The structure of the locking surface, which is formed by being formed substantially perpendicular to the movable cavity forming surface at an inclination angle of ± 0 to 5 degrees with respect to the mold releasing direction, is advantageously employed. .

That is, in the disk forming die having the structure according to the second aspect of the present invention, the inner surface on the outer peripheral side of the undercut-shaped forming recess and the disk base formed by the forming recess are provided. The outer surface of the stack rib is
By locking the disk base in the mold release direction, a locking force is exerted against the release of the disk base from the movable die. If the angle of inclination of the undercut-shaped engaging surface with respect to the mold release direction is smaller than 1 degree, there is a possibility that an effective engaging force may not be easily exerted due to shrinkage at the time of molding of the disk base. If the angle is larger than 5 degrees, the locking force becomes too large, which may cause a product defect such as chipping at the time of releasing the mold, and also has a problem that the manufacturability of the movable mold is deteriorated.

According to a third aspect of the present invention, there is provided a disk forming die having a structure according to the present invention, wherein the inner surface of the inner side of the forming recess which is substantially perpendicular to the cavity forming surface; By being engaged with the inner peripheral surface of the stack rib of the disc base formed by the shrinkage at the time of molding of the disc base by a fitting action or a shape locking action,
The locking force is exerted against the release of the disk base from the movable die. If the angle of inclination of the substantially perpendicular locking surface with respect to the release direction exceeds 5 degrees in the undercut direction, the locking force becomes too large, and product defects such as chipping during release may occur. In addition, there is a problem that the manufacturability of the movable mold is deteriorated. On the other hand, in the direction opposite to the undercut direction, by setting the inclination angle to 5 degrees or less, the locking force due to the fitting action due to shrinkage during molding of the disk base can be extremely effectively exerted.

Furthermore, as described in claim 4, the inner surface on the inner peripheral side of the molding recess is oriented in a direction that does not form an undercut shape with respect to the releasing direction of the fixed mold and the movable mold. By forming at an inclination angle of ~ 20 degrees,
It is also effective to configure the locking surface according to the first aspect of the present invention. In the disk forming die having the structure according to the fourth aspect of the present invention, by setting the inclination angle of the inner peripheral side surface of the forming recess to 20 degrees or less, the effective locking force to the disk base is reduced. In addition to this, air entrapment and the like by the undercut portion can be effectively reduced or avoided at the time of emphasizing the cavity of the molding material. Therefore, the filling speed of the molding material can be increased while avoiding molding defects such as sink marks and silver streaks due to air entrainment and the like, and the molding cycle can be improved.

Alternatively, at least the inner surface of the molding recess on the inner peripheral side may be rougher than a cavity forming surface forming the surface of the disk base. 2. The structure according to claim 1, wherein the inner surface on the inner peripheral side is formed at an inclination angle of 0 to 30 degrees in a direction not forming an undercut shape with respect to the release direction of the fixed mold and the movable mold. 3. It is also effective to configure the stop surface. In such a disk mold having a structure according to the invention described in claim 5,
By roughening the inner peripheral side surface of the forming recess forming the locking surface, without providing an undercut portion, by setting the inclination angle of the inner peripheral surface side of the forming recess to 30 degrees or less, By the mechanical or physical locking action, an effective locking force to the disk base can be obtained. Therefore, it is possible to further increase the molding material filling speed while avoiding molding defects such as sink marks and silver streaks caused by air entrapment by the undercut portion, and further improve the molding cycle. You get.

According to the fifth aspect of the present invention, if the inner surface of the molding recess forming the locking surface is rougher than at least the mirror-finished cavity forming surface, the effect of improving the locking force is improved. In consideration of the size of the angle of inclination of the inclined surface and the type of molding material, it is also necessary to consider the prevention of molding defects and the securing of molding cycles to the extent that the desired locking force is exhibited. In general, when molding an ordinary optical disk, the surface roughness test value (maximum height: R _max ) of JIS standard is set to a range of several μm to several tens μm. preferable. Further, it goes without saying that the maximum allowable value of the surface roughness of the inner surface of the molding recess is limited by the allowable value of the surface roughness of the disk base as a product. Further, it is of course possible to make the entire inner surface of the molding recess rough.

Further, in the disk forming die having the structure according to the first to fifth aspects of the present invention, the depth of the forming recess is set in consideration of the standard of the disk, the manufacturability of the die, and the like. , So that an effective locking force can be exerted, and the depth is generally 0.15 to 0.40 mm from the surface of the cavity forming surface of the movable die. In addition, since the stack rib is generally formed in an annular shape extending continuously in the circumferential direction of the disk base, the locking surface that exerts a locking force in the release direction on the disk molded product is formed by the concave groove. Although it is desirable to provide a substantially cylindrical surface continuously over the entire circumference of the place, a locking surface may be provided on a part or a part of the circumference of the molding recess.

Further, the present invention according to claims 1 to 5,
Either of them can be advantageously applied to a disk mold having a structure in which the cavity forming surface of the fixed mold is constituted by a mirror surface, but in particular, as described in claim 6, with respect to the cavity forming surface of the fixed mold. The present invention is advantageously applied to a disk mold on which a stamper is mounted.

In the disk forming die having the structure according to the sixth aspect of the present invention, even when a stamper having poor releasability is mounted on the cavity forming surface of the fixed die, the die is not opened. An effective locking force is applied to the movable base on the disk base, and the disk base is left and held on the movable base side, thereby enabling stable continuous molding.

[0020]

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

First, FIG. 1 shows a mold for molding an optical disc substrate as a first embodiment of the present invention. This molding die includes a fixed die 10 and a movable die 12, and although not shown, the fixed die 10 is attached to a fixed plate of a mold clamping device, while the movable die 12 is The fixed die 10 and the movable die 12 are opened and closed by being mounted on and supported by the movable plate of the apparatus, and by driving the movable plate toward and away from the fixed plate. Then, as shown in FIG.
By molding the movable mold 12 and the movable mold 12, a disc molding cavity 14 is formed between the mold-matching surfaces.

More specifically, the fixed mold 10 is provided with a fixed mirror block 16 on the side where the molding cavity 14 is formed, and a cylindrical stamper retainer 18 penetrates a central portion of the fixed mirror block 16. Further, the stamper presser 1
A fixed-side insert sleeve 20 is inserted into the center hole of the fixed mirror block 8 and assembled. The surface of the fixed mirror block 16 and the axial end faces of the stamper retainer 18 and the fixed-side insert sleeve 20 cooperate to form a fixed side insert sleeve. A cavity forming surface 22 is configured.

An annular block-shaped holding ring 24 is attached to the outer periphery of the fixed mirror block 16, and the inner periphery of the holding ring 24 has an outer periphery projecting above the fixed-side cavity forming surface 22. While the presser claw 26 is formed, the stamper presser 18 has an inner peripheral presser claw 28 (see FIG. 2) protruding above the fixed-side cavity forming surface 22 at the inner peripheral edge of the fixed mirror block 16. . When the optical disc substrate is formed, a thin annular plate-shaped stamper 30 (see FIG. 2) is provided on the fixed-side cavity forming surface 22, and the stamper retainer 18 is fitted into the center hole thereof and positioned. The inner and outer peripheral edges are held by the outer peripheral pressing claws 26 of the press ring 24 and the inner peripheral pressing claws 28 of the stamper press 18 so that the inner and outer peripheral portions are mounted.

Furthermore, the fixed-side insert sleeve 20
A sprue bush 32 is attached to a center hole of the sprue bushing. As shown in FIG. 2, a molding resin material injected from a nozzle of an injection device (not shown) is guided to the molding cavity 14 through the sprue bush 32 to be filled. Cavity 14
By molding and cooling the resin material inside, the optical disk substrate 33 to which the information (concavo-convex shape) of the stamper 30 is transferred is formed.

The fixed-side insert sleeve 20 is
The inner peripheral side portion of the axial end face is recessed, thereby forming an annular step 34 (see FIG. 2) extending in the circumferential direction at the central portion of the axial end face. The edge of the step portion 34 constitutes a female cutter for punching a central hole of the optical disk substrate.

Although not explicitly shown in the drawings, a compressed air passage is formed inside the fixed mold 10, and compressed air guided through the compressed air passage is fixed to the stamper presser 18. The gas is ejected to the fixed-side cavity forming surface 22 through a gap with the side insert sleeve 20. The compressed air blown to the fixed-side cavity forming surface 22 causes the molding cavity 14
The mold release force from the fixed mold 10 is applied to the optical disk substrate 33 (see FIG. 2) molded at the time of opening the mold.

On the other hand, the movable mold 12 is provided with a movable mirror block 36 on the side where the molding cavity 14 is formed, and a movable insert sleeve 38 is mounted and fixed through a central portion of the movable mirror block 36. At the same time, an ejector sleeve 40 is provided so as to be movable in the axial direction through a center hole of the movable insert sleeve 38. A movable cavity forming surface 42 is formed by cooperation of the surface of the movable mirror block 36 and the axial end surfaces of the movable insert sleeve 38 and the ejector sleeve 40.

Further, in the inner hole of the ejector sleeve 40, a male cutter sleeve 44 and an inner sleeve 46 are sequentially inserted and disposed.
, An ejector pin 48 is inserted and arranged in the axial direction. The male cutter sleeve 44, the inner sleeve 46, and the ejector pin 48 form a runner portion that guides the resin material guided through the sprue portion to the molding cavity 14 between the surfaces facing the fixed mold 10. ing.

Then, as shown in FIG. 2, after filling the molding cavity 14 with the resin material, the male cutter sleeve 44 is protruded, and the step portion 34 formed on the fixed side insert sleeve 38 is formed. The central hole of the optical disk substrate 33 is formed by punching. Further, after the resin material filled in the molding cavity 14 is cooled and solidified and the mold is opened, the ejector sleeve 40 is operated to protrude, whereby the optical disc substrate 33 molded and held on the movable mold 12 side. Is released from the movable mold 12 and is taken out, and the ejector pin 48 is caused to protrude, whereby the sprue runner 50 remaining and held on the movable mold 12 side is moved. The mold 12 is released from the mold 12 and taken out.

Although not explicitly shown in the drawings, an air passage is formed inside the movable mold 12, and after the mold is opened, compressed air supplied through the air passage is
Movable mirror block 36 and movable insert sleeve 3
8 is ejected to the movable-side cavity forming surface 42 through an air passage formed in a gap between the movable-side insert sleeve 38 and an air passage formed in a gap between the movable-side insert sleeve 38 and the ejector sleeve 40. Thus, a release force is exerted on the optical disk substrate 33. At the time of opening the mold, by applying a negative pressure suction force through the air passage, a suction suction force to the movable mold 12 side is exerted on the optical disk substrate 33 formed by the molding cavity 14. It is also possible.

Further, the movable insert sleeve 38 has an annular end surface which forms the movable cavity forming surface 42 and has an annular shape which is open to the movable cavity forming surface 42 and extends circumferentially on the central axis. A recess 52 is formed. As shown in FIG. 2, when the optical disc substrate is molded, the molding recess 52 is filled with a resin material, so that the resin material protrudes from one surface of the optical disc substrate and is located inside the signal recording area. An annular stack rib 54 extending in the circumferential direction on the circumferential side is integrally formed.

Here, the molding recess 52 has a substantially rectangular or trapezoidal cross section with a substantially flat bottom surface. The inner surface on the inner peripheral side of the molding recess 52 is formed as a comparatively gentle inclined surface 56 so as to gradually decrease in diameter toward the opening side and open. An overhang surface 58 having an undercut shape whose diameter gradually decreases toward the side is formed.

As a result, the stack rib 54 formed in the molding recess 52 at the time of molding the optical disc substrate 33 is formed in a state of being inserted into the undercut molding recess 52 in the outer peripheral portion thereof. The outer peripheral portion of the stack rib 54 is formed so as to overlap the outer peripheral wall portion of the molding recess 52 in the axial direction (the releasing direction or the mold opening / closing direction). As a result, the optical disc substrate 33 is formed based on a shape or physical locking action or frictional force action based on the contact of the outer peripheral surface 60 of the stack rib 54 with the overhang surface 58 of the molding recess 52 in the optical disc board 33. Is locked to the movable mold 12, and the movable mold 1 of the optical disc substrate 33 is
The resistance to the release from the mold 2 is exhibited. As is clear from this, in the present embodiment, the locking surface is constituted by the overhang surface 58.

By the locking action of the stack rib 54 with respect to the molding recess 52, when the mold opening of the optical disc base 33 is completed, the optical disc base 33 is moved toward the movable mold 12 until the mold opening is completed. Advantageously, it will remain and be retained. In particular, in the present embodiment, when the mold is opened, compressed air is ejected to the cavity forming surface 22 of the fixed mold 10, so that the optical disc substrate 33 is positively released from the fixed mold 10 and the movable mold is moved. By exerting a suction force on the optical disk substrate 33 by negative pressure suction from the cavity forming surface 42 of the mold 12, the optical disk substrate 33 is more advantageously held on the movable mold 12 side.

As a result, at the time of opening the mold, the optical disk substrate 33 is advantageously released from the fixed mold 10 and held on the movable mold 12 side.
The optical disc substrate 33 is moved to the movable mold 12 until the forcible release force from the movable mold 12 is exerted on the optical disc substrate 33 by the projecting operation of the ejector sleeve 40 and the blowing of air onto the movable-side cavity forming surface 42. Can be surely held on the cavity forming surface 42 of the semiconductor device.
Then, the movable mold 12 of the optical disc substrate 33 based on the action of the forcible release force by the ejector sleeve 40 and the like.
As a result, the mold release and take-out can be performed extremely stably, so that the optical disc substrate 33 can be continuously and stably formed.

The molding recess 52 in the movable mold 12
The angle of inclination of the overhang surface 58 varies depending on the cooling time, mold temperature, resin material temperature, etc., and takes into consideration the molding shrinkage of the resin material, the depth of the molding recess 52, and the like. The depth D of the molding recess 52 in the movable mold 12 is also determined in consideration of the product standard of the optical disk, and the optical disk substrate 33 is opened when the mold is opened.
Is set so that an effective locking force can be exhibited. For example, in molding a CD having a diameter of 120 mm from a polycarbonate resin material, cooling time: 2.
When the mold temperature is 75 ° C. and the resin temperature is 330 ° C., in general, the inclination angle α of the overhang surface 58 with respect to the mold release direction (the horizontal direction in FIG. 2) is 1 ° ≦ α ≦ 5 °.
And the depth of the molding recess 52: D is D =
It is desirable to set each so as to be 0.15 mm to 0.40 mm. If α <1 °, a gap may be generated between the overhang surface 58 of the molding recess 52 and the outer peripheral surface 60 of the stack rib 54 due to the molding shrinkage of the resin material, and the effective locking force may not be exhibited. While α>
In the case of 5 °, the amount of engagement between the overhang surface 58 of the molding recess 52 and the outer peripheral surface 60 of the stack rib 54 in the release direction becomes too large, and product defects such as chipping of the stack rib 54 at the time of release are caused. This is because it may occur.

Therefore, in the optical disk molding die having the above-described structure, the optical disk substrate 33 is moved to the movable mold 12 side when the mold is opened by using the conventionally formed stack rib forming portion (52). The locking mechanism to hold the optical disk without increasing the number of special members, drastically modifying the mold, and reducing the manufacturability of the optical disk substrate.
Advantageously, it is possible to stably and continuously form the optical disc substrate 33,
Even when the stamper 30 having poor releasability is mounted on the fixed mold 10, the optical disc substrate 33 is advantageously held on the movable mold 12 side when the mold is opened, and stable continuous molding can be realized. .

FIG. 3 shows a main part of a disk molding die according to a second embodiment of the present invention. In this embodiment, the forming recess 52 of the stack rib 54 is different from the disk forming die of the first embodiment.
FIG. 3 shows another example of the shape, and in order to facilitate understanding thereof, in FIG. 3, members and portions corresponding to those in FIG. The same reference numerals as in the embodiment are attached.

That is, in the present embodiment, the movable mold 12
In the forming recess 52 having a substantially rectangular or trapezoidal cross section with a substantially flat bottom surface, the inner surface on the outer peripheral side gradually increases in diameter toward the opening and opens. While it is a relatively gentle slope 66,
The inner surface on the inner peripheral side is a vertical surface 68 extending substantially perpendicularly to the depth direction from the movable-side cavity forming surface 42.

Thus, in this embodiment, the molding recess 5
No effective locking action on the molded disk base 33 due to the inclined surface 66 on the outer peripheral side of 2 can be expected, but instead, the vertical surface 68 on the inner peripheral side of the molded recess 52 allows the disk base 33 to be fixed. An extremely effective locking action is exerted. That is, the stack rib 54 formed by the molding recess 52 at the time of molding the optical disc substrate 33
However, by reducing the diameter due to molding shrinkage of the resin material,
The inner peripheral surface 70 is adapted to be fitted to the vertical surface 68 of the molding recess 52. As a result, the inner peripheral surface 70 of the stack rib 54 on the optical disc substrate 33
The optical disk substrate 33 is locked to the movable mold 12 based on the frictional force effect based on the fitting of the molding recess 52 to the vertical surface 68, and the like.
The resistance to release from the movable mold 12 of the optical disk substrate 33 is exerted. In addition,
As is apparent from this, in the present embodiment, the locking surface is constituted by the vertical surface 68.

Therefore, also in the optical disk molding die of the present embodiment, similarly to the optical disk molding die of the first embodiment, the locking action of the stack rib 54 on the molding recess 52 is exerted, and the optical disk substrate 33 is formed. When opening the mold after molding, the optical disc substrate 33 is opened until the mold opening is completed.
Is advantageously retained and held on the movable mold 12 side, and the ejector sleeve 4 after the mold opening is completed.
The ejection of the optical disk substrate 33 based on the protrusion operation of the optical disk substrate 3 can be performed extremely stably.
3 can be continuously and stably formed.

The molding recess 52 in the movable mold 12
The vertical surface 68 may be any surface that can exert an appropriate locking force on the inner peripheral surface 70 of the stack rib 54 in the optical disk substrate 33 when the mold is opened. May be slightly inclined from a desired direction (that is, a releasing direction).

Specifically, as shown in FIG.
A relatively steep inclination angle β may be set with respect to the vertical surface 68 so as to gradually decrease in diameter toward the opening side of the molding recess 52 and open, or as shown in FIG. Alternatively, the inclination angle γ may be set in a direction of forming an undercut-shaped overhang surface whose diameter gradually increases toward the opening side of the molding recess 52 with respect to the vertical surface 68.

The values of the inclination angles β and γ when the inclination angle is set on the vertical surface 68 are the same as the inclination angles of the overhang surface 58 in the first embodiment, the cooling time, the mold temperature, and the resin material temperature. In consideration of the above, it is set so that an appropriate locking force is exerted on the optical disc substrate 33 when the mold is opened. However, if γ is set too large,
Since the engaging force or the amount of engagement between the inner peripheral surface 70 of the stack rib 54 and the vertical surface 68 of the molding recess 52 in the releasing direction becomes too large, there is a possibility that the releasing property may be impaired. ≤
It is desirable to set to 5 °. On the other hand, β is β ≦
By setting the angle to 5 ° and making the inner peripheral side surface (68) of the forming recess 52 substantially vertical, the locking based on the fitting of the inner peripheral surface 70 of the stack rib 54 and the vertical surface 68 of the forming recess 52 is performed. Power
It can be used very effectively.

However, when the locking surface is formed by the inner peripheral surface of the molding recess 52, the locking force is effectively made by the fitting action of the stack rib 54 to the locking surface based on the molding shrinkage of the resin material. Therefore, the inner peripheral surface of the molding recess 52 does not necessarily have to be substantially vertical. Specifically, as shown in FIG. 6, the inner peripheral surface 80 of the molding recess 52 constituting the locking surface is shown as a main part of a disk molding die as still another embodiment of the present invention. By setting the value of the inclination angle θ with respect to the direction perpendicular to the movable-side cavity forming surface 42 (the mold release direction) so that θ ≦ 20 °, a practically effective locking force can be obtained. It can be applied to the optical disc substrate 33.

In particular, by setting the inclination angle θ of the inner peripheral surface 80 in the range of 0 ° ≦ θ ≦ 20 ° to avoid the overhang surface, the molding resin material caused by the undercut shape is formed. This effectively prevents the entrapment of air during the injection filling of the molding cavity, and increases the filling speed of the molding resin material while preventing molding defects such as sink marks and silver streaks. As a result, both the improvement of the molding cycle and the improvement and stabilization of the product quality can be advantageously achieved.

Further, when the locking surface is formed by the inner peripheral surface 80 of the molding recess 52 as described above, the inner peripheral surface 80 is slightly roughened to reduce molding shrinkage of the resin material. The locking force to the disk base 33 can be more effectively obtained based on the biting of the stack rib 54. The degree of surface roughness of the inner peripheral surface 80 can be improved at least by making the inner peripheral surface 80 rougher than the cavity forming surface 42. However, when the inner peripheral surface 80 is made too rough, the surface quality of the disk base is reduced. In practice, in consideration of the inclination angle θ of the inner peripheral surface 80 and the depth D of the molding recess 52, a general optical disc substrate is JIS standard. The surface roughness test value (maximum height: _Rmax ) is desirably set in the range of several μm to several tens μm.

By roughening the inner peripheral surface 80, the value of the inclination angle: θ of the inner peripheral surface 80 becomes
Within the range of 30 °, it is possible to secure an effective locking force with respect to the disk base 33.
By avoiding the overhang surface within the range of ≤θ≤30 °, and by setting the inclination angle: θ large, it is possible to prevent the entrainment of air during molding, and to improve the injection filling speed of the resin material and, consequently, the molding cycle. It is also possible to plan.

In FIG. 6, in order to facilitate understanding, members and portions having the same structure as those of the second embodiment are respectively shown in FIG. The same reference numerals are given to them.

The embodiments of the present invention have been described above, but these are merely examples, and the present invention
The description of these embodiments should not be construed as limiting in any way.

For example, in the above embodiment, the molding recess 52
The locking surface for the optical disc molded product is constituted only by either the inner surface on the inner peripheral side or the inner surface on the outer peripheral side, but the engaging surface is constituted by both the inner surface on the inner peripheral side and the inner surface on the outer peripheral side. It is also possible.

Further, in addition to the molding die in which the stamper is mounted only on the fixed die side as illustrated, the molding die in which the stamper is mounted only on the movable die side, and the molding die in which the stamper is mounted on both the movable die and the fixed die. On the other hand, the present invention can be advantageously applied.

In addition, although not enumerated one by one, the present invention can be embodied in embodiments in which various changes, modifications, improvements, etc. are made based on the knowledge of those skilled in the art. It goes without saying that any of them is included in the scope of the present invention unless departing from the gist of the present invention.

[0054]

As is apparent from the above description, in the disk forming dies according to the first to sixth aspects of the present invention, all of the dies are formed by utilizing the formation portions of the stack ribs. A locking mechanism for retaining and holding the disk base on the movable die side when the mold is opened can be advantageously realized with a simple structure, thereby stabilizing the removal operation of the disk base by the removal mechanism after the mold is opened. Therefore, the continuous formability of the disk base can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing a mold matching state of a disk molding die as one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an enlarged main part of the disk molding die shown in FIG. 1;

FIG. 3 is an explanatory view corresponding to FIG. 2, showing an enlarged main part of a disk molding die as a second embodiment of the present invention.

FIG. 4 is an explanatory view of a main part showing another specific example of a forming recess in the disk forming die shown in FIG. 3;

FIG. 5 is an explanatory view of a main part showing still another specific example of a molding recess in the disk molding die shown in FIG. 3;

FIG. 6 is an explanatory view corresponding to FIG. 3 and showing an enlarged main part of a disk forming die as still another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 fixed mold 12 movable mold 14 molding cavity 30 stamper 33 optical disk substrate 40 ejector sleeve 42 movable cavity forming surface 52 molding recess 54 stack rib 58 overhang surface 60 outer peripheral surface 68 vertical surface 70 inner peripheral surface

Claims (6)

[Claims] 1. A take-out device comprising a fixed mold and a movable mold which form a molding cavity by being matched with each other, and taking out a disk base formed by the molding cavity by releasing the mold after opening the mold. A mechanism for forming a stack rib extending in a circumferential direction by protruding from one surface of the disk base with respect to a cavity forming surface of the movable die in a disk forming die provided on the movable die side; In addition to the provision of the recess, at least one of the inner surfaces on the inner peripheral side and the outer peripheral side of the molded concave portion is a locking surface that exerts a locking force on the disk base in the releasing direction when the mold is opened. Mold for forming discs. 2. The method according to claim 1, wherein an inner surface on an outer peripheral side of the molding recess has an undercut shape having an inclination angle of 1 to 5 degrees with respect to a releasing direction of the fixed mold and the movable mold. 2. The disk molding die according to claim 1, wherein a stop surface is formed. 3. An inner surface on an inner peripheral side of the molding recess has an inclination angle of ± 0 to 5 degrees with respect to a mold releasing direction of the fixed mold and the movable mold, and is formed with respect to the movable-side cavity forming surface. The disk molding die according to claim 1, wherein the locking surface is formed by being formed substantially vertically. 4. An inner surface on an inner peripheral side of the molding recess is formed at an inclination angle of 0 to 20 degrees in a direction not forming an undercut shape with respect to a releasing direction of the fixed mold and the movable mold. The locking surface is constituted by:
4. The disk molding die according to 1. 5. An inner surface of at least an inner peripheral side of the molding recess is rougher than a cavity forming surface forming a surface of the disk base, and an inner surface of the inner peripheral side is a fixed mold. 3. The disk according to claim 1, wherein the locking surface is formed by being formed at an inclination angle of 0 to 30 degrees in a direction that does not become an undercut shape with respect to a mold release direction of the movable mold. 4. Mold for molding. 6. A stamper is mounted on the fixed mold cavity forming surface.
A disk molding die according to any one of the above.