JPH0422416B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a mold for a disk base, and in particular, to a mold for forming a disk substrate, and in particular, it is a mold for molding a disk substrate. The present invention relates to a technology for solving the problem of product defects caused by molding, prolonging the life of stampers, and simplifying the maintenance and management of molds.

(Prior Art) Disc bases such as optical disc bases such as video discs and compact discs are usually manufactured by injection molding. In general, for injection molding, the inner peripheral edge is held by a stamper holder and the outer peripheral edge is held by an outer ring on the mirror surface of a movable side mirror plate disposed in a movable mold. By disposing a stamper engraved with predetermined information and matching the movable mold to the fixed mold, the movable mirror plate disposed on the movable mold and the fixed mold A mold is used in which the molding surface on the movable mold side forms a cavity defined by the stamper between the movable mold side and a fixed mirror plate provided therein. By injecting a predetermined resin material into the cavity of such a mold, it is possible to mold a disk base onto which information from the stamper has been transferred.

By the way, in such a molding mold for a disk base, when molding the disc base, the mold is
Because it is heated to a high temperature of .degree. C. or higher, as shown in FIG. Gaps 8, 10, 1 are provided between the outer peripheral edge of the stamper 4 held by the outer ring 6 and on the outside of the outer peripheral surface of the stamper 4 to allow thermal expansion of the stamper 4, respectively.
2 is formed, so that the stamper 4 can substantially rotate with respect to the movable mirror plate 14.

(Problem) For this reason, in conventional disk base molds, the stamper 4 rotates around its center line due to the pressure of the resin material injected into the cavity when it flows. The back surface 18 of the stamper 4 and the mirror surface 1 of the movable side mirror plate 14 may take several hundred shots in some cases, or several thousand shots in the slow case.
6, a countless number of scratches occur in the circumferential direction, and these scratches are transferred to the product side.
There was a problem that made it impossible to mold a disk base of good quality. In particular, these scratches are several micrometers deep and extend several millimeters in the circumferential direction;
This cannot be detected at all from the surface side of the stamper (product cavity side), and as a result, defective products suddenly occur. Therefore, in order to stably mold a high-quality disk substrate using a conventional disk substrate mold, it is necessary to use a stamper 4.
There was a problem in that the mirror surface 16 of the movable mirror plate 14 had to be periodically polished with a polishing liquid or the like in addition to replacing the movable mirror plate 14 periodically.

(Solution Means) Here, the present invention has been made against the background of the above-mentioned circumstances, and its gist is to provide a mold for a disk base as described above, in which the outer circumferential ring of the movable side mirror plate is A protrusion is provided at a portion corresponding to the outer circumferential edge of the stamper held by the movable side mirror plate and protrudes by a predetermined dimension from the mirror surface of the movable side mirror plate, and a protrusion is provided at a portion corresponding to the outer circumferential edge of the stamper so that the protrusion protrudes. forming an engagement hole that
The purpose is to prevent the stamper from rotating around the center line based on the engagement between the protrusions and the engagement holes.

(Function/Effect) In such a mold for a disk base, there is a gap between the stamper holder and the inner circumferential edge of the stamper held by the stamper holder, and between the outer circumferential ring and the outer circumferential edge of the stamper held by the outer circumferential ring. Even if a gap is formed between the peripheral edge and the outside of the outer circumferential surface of the stamper to allow thermal expansion of the stamper, the engagement between the projection formed protruding on the movable side mirror plate and the stamper is Based on the engagement with the matching hole, the stamper is effectively prevented from rotating around its center line, and therefore, the rotation of the stamper causes the back surface of the stamper and the mirror surface of the movable mirror plate to be prevented. This also effectively prevents circumferential scratches. And like this,
Since the occurrence of scratches on the stamper and the mirror plate on the movable side is effectively prevented, the occurrence of defective products due to the transfer of scratches on the back side of the stamper that cannot be confirmed during molding can be effectively prevented. In addition, compared to conventional molds, the life of the stamper has been significantly improved, and the intervals between stamper replacement and polishing of the mirror surface of the movable side mirror plate have been significantly lengthened. This made maintenance and management of the system much easier.

(Example) Hereinafter, in order to clarify the present invention more specifically, one example thereof will be described in detail based on the drawings.

First, FIG. 1 shows a sectional view of essential parts of a mold for a disk base according to the present invention. There, 20 is a movable side mirror plate 24 of the movable mold 22.
This is a mirror surface plate on the fixed side of the fixed mold 28 that forms a disc-shaped cavity 26 between the fixed mold 28 and is attached to the fixed mold main body 32 via the back plate 30. and is attached to a fixed platen 34. On the other hand, such fixed side mirror plate 2
A movable mold 2 that forms a cavity 26 with
The movable side mirror plate 24 of No. 2 is attached to the movable mold body 40 via the back plate 36 and the intermediate plate 38, and further attached to the movable platen 42 via the movable die body 40. Based on the operation of a clamping cylinder (not shown), it can be moved integrally with the movable platen 42 in the left-right direction in FIG.

Here, the fixed side mirror plate 20 is disposed with its back side accommodated in a recess 44 formed in the fixed mold body 32; An annular tapered surface 48 is formed on the opening end surface to fit into a tapered surface 46 of a movable mold main body 40, which will be described later.

Further, the fixed mold 28 includes a fixed side mirror plate 20,
A sprue bush 50 is disposed to pass through the back plate 30 and the fixed mold body 32 concentrically with the cavity 26 and to be movable a predetermined distance in the axial direction.
A predetermined resin material is supplied to the cavity 26 through the spool bushing 50 from an injection device (not shown).
It is designed so that it can be ejected inside.

On the other hand, in the movable mold body 40 of the movable mold 22,
A recess 52 is formed that is concentric and has the same diameter as the recess 44 of the fixed mold body 32, and the movable mirror plate 24 is disposed within the recess 52. Then, the recess 52 of the movable mold body 40
An annular tapered surface 46 is formed on the opening end surface of the fixed mold body 32 to be fitted with the tapered surface 48 of the fixed mold body 32. By fitting these tapered surfaces 46 and 48, the fixed mold 28 and the movable mold 28 are connected to each other. Center alignment with the mold 22 is performed.

Further, as shown in FIG. 1, the movable mold 22 includes a mirror plate 24, a back plate 36, and an intermediate plate 38.
and passing through the movable mold body 40 coaxially with the spool bushing 50 of the fixed mold 28,
A hollow gate cutter 54 having the same outer diameter as the sprue bush 50 is disposed, and the distal end of the gate cutter 54 is moved by the protrusion operation of an ejection rod 56 disposed through the movable platen 42. It is adapted to protrude by a predetermined distance toward the cavity 26 side. Then, the ejector pin 5
8 and an ejector tube 60 are slidably fitted to each other, and the distal ends thereof can protrude by a predetermined distance toward the cavity 26 from the retracted position shown in FIG. . The ejector pin 58 and the ejector sleeve 60 are moved in the axial direction by ejector cylinders 62 and 64 provided at their base ends, respectively.

By the way, on the outside of the ejector sleeve 60, on the inner peripheral surface, the ejector sleeve 60 is
While being slidably fitted to the outer peripheral surface of , a substantially cylindrical stamper holder 70 having an annular stamper holding claw 68 (see FIG. 2) on the outer periphery of the end on the side of the cavity 26 is removably disposed. On the outer circumference on the side of the mirror surface 72, an outer circumferential ring 76 is provided with an annular stamper holding claw 74 that protrudes radially inward.
is removably attached. And the second
As shown in detail in the figure, the molding surface of the disk base is formed with the inner and outer peripheral edges held by the stamper holding claws 68 of the stamper holder 70 and the stamper holding claws 74 of the outer ring 76, respectively. A stamper 80 with predetermined information engraved on the surface 78 is disposed.

Note that, as shown in FIG. 2, the stamper holding claw 68 of the stamper holder 70 and the stamper 80
and between the stamper holding claw 74 of the outer ring 76 and the stamper 80, and between the stamper 80
Between the outer peripheral surface of the outer peripheral ring 76 and the inner peripheral surface of the outer peripheral ring 76,
As with conventional molds, gaps 82, 84 and 86 are formed to allow thermal expansion of stamper 80, respectively. Moreover, as is clear from FIG. 1, the outer peripheral surface of the cavity 26 is
It is defined by the stamper holding claws 74 of the outer ring 76 .

Here, in such a mold, as shown in detail in FIGS. 2 and 3, the stamper is held by the stamper holding claws 74 of the outer ring 76 of the movable mirror plate 24. Stamper 8
A pair of pins 88, 88 as protrusions that protrude by a predetermined dimension from the mirror surface 72 are erected symmetrically across the center line of the movable mirror plate 24, located at a portion corresponding to the outer peripheral edge of the movable mirror plate 24. A pair of notches of a predetermined depth are located at the outer peripheral edge portion of the stamper 80 corresponding to the erected portions of the pins 88, 88, and have a structure in which the outer peripheral portion is cut out. Grooves 90, 90 are formed, and the stamper 80 is disposed on the mirror surface 72 of the movable mirror plate 24 with the pins 88, 88 protruding into the notched grooves 90, 90.

In addition, as shown in FIG.
The amount of protrusion from the mirror surface 72 of 8 and 88 is as follows:
The distance between the mirror surface 72 and the stamper holding claw 74 of the outer ring 76 is slightly longer than the distance between the mirror surface 72 and the stamper holding claw 74 of the outer ring 76. 92, 92 is being forced to enter. Also,
As shown in FIGS. 2 and 3, the cutout grooves 90, 90 of the stamper 80 have a width that is approximately the same as the diameter of the pin 88, and the bottom wall of these grooves and the pin 88 , 88, the stamper 80
They are formed to have a depth that forms gaps 94, 94 that allow for thermal expansion.

According to such a mold for a disk base, there is a gap between the stamper holding claw 68 of the stamper holder 70 and the stamper 80, between the stamper holding claw 74 of the outer circumferential ring 76 and the stamper 80, and between the outer circumferential surface of the stamper 80 and the outer circumferential ring. 76 and between the bottom walls of the cutout grooves 90, 90 of the stamper 80 and the pins 88, 88 erected on the movable side mirror plate 24, the thermal expansion of the stamper 80 is prevented. Since the gaps 82, 84, 86 and 94 are formed to allow the transfer of the information on the stamper 80, by injecting a predetermined resin material into the cavity 26 through the sprue bush 50, the information on the stamper 80 can be transferred. The disk base can be molded using conventional molds.

In the mold of this embodiment, as described above, the pins 88 and 8 are provided upright on the movable mirror plate 24.
8 are cutout grooves 90, 90 formed in the stamper 80.
Because the stamper 80 is inserted into the center, the stamper 80 does not rotate around its center line even though the gaps 82, 84 and 86 are provided to allow thermal expansion of the stamper 80 as described above. Therefore, the stamper 80 is well prevented from rotating around its center line during molding of the disk base, and the back surface 96 of the stamper 80 and the movable side mirror plate 24 are prevented from rotating. This effectively prevents scratches from occurring on the mirror surface 72 in the circumferential direction.

Therefore, deterioration of the quality of the forming disk base due to the occurrence of such scratches transferred to the product side is effectively prevented, and the life of the stamper 80 is substantially improved. Furthermore, the interval between replacement of the stamper 80 and the interval between polishing operations on the mirror surface 72 of the movable side mirror plate 24 can be significantly increased, and maintenance management of the mold can be significantly simplified.

In the mold of this embodiment, the center hole of the disk base is punched out by the ejection of the gate cutter 54 toward the cavity 26 by the ejection rod 56.

Moreover, after the punching operation of the center hole,
After the molds 22 and 28 are opened, the ejector pin 58 and the ejector sleeve 60 are inserted into the cavity 2 in the corresponding ejector cylinders 62 and 64, respectively.
By being pushed out to the 6 side, the resin in the central hole punched portion and the disk base as a product are released from the movable mold 22.

Although one embodiment of the present invention has been described in detail above,
This is a literal illustration, and the present invention should not be construed as being limited to these specific examples, and the present invention can be implemented in various forms with various changes, modifications, improvements, etc. without departing from the spirit thereof. Of course.

For example, in the above embodiment, the pin 8 as a protrusion
Two sets of pins 88 and notched grooves 90 serving as engagement holes are provided, and rotation of the stamper 80 around the center line is prevented by engagement between the two sets of pins 88 and notched grooves 90. However, it is sufficient to provide only one set of such projections and engaging holes, and if necessary, three or more sets may be provided. Further, the engagement hole may be formed as an elongated hole that is long in the radial direction of the stamper 80.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a main part showing an example of a mold for a disk base according to the present invention, and FIGS. 2 and 3 respectively show how a stamper is attached to the mirror plate on the movable side of the mold shown in FIG. It is an explanatory view for explaining an attachment state. FIG. 4 is a diagram corresponding to FIG. 2 showing a conventional example. 20: Fixed side mirror plate, 22: Movable mold, 24:
Movable side mirror plate, 26: Cavity, 28: Fixed mold, 34: Fixed plate, 42: Movable plate, 70: Stamper holder, 72: Mirror surface (movable side mirror surface), 76:
Outer ring, 80: Stamper, 82, 84, 8
6, 94: Gap, 88: Pin (protrusion), 90: Notch groove (engaging hole), 96: Back surface (of stamper).

Claims (1)

[Scope of Claims] 1. Predetermined information is printed on the mirror surface of a movable side mirror plate disposed on a movable mold by holding the inner peripheral edge with a stamper holder and holding the outer peripheral edge with an outer peripheral ring. By disposing a stamper engraved with the movable mold and matching the movable mold to the fixed mold, the movable side mirror plate on which the movable mold is disposed and the fixed mold are arranged. The molding surface on the movable mold side forms a cavity defined by the stamper between the mirror plate on the fixed side and the information on the stamper is injected into the cavity. In the disk base molding die configured to mold a disk base onto which is transferred, the movable mirror plate is located at a portion of the movable mirror plate corresponding to the outer peripheral edge of the stamper held by the outer ring, A protrusion is provided that projects from the mirror surface of the side mirror plate by a predetermined dimension, and an engagement hole is formed at the outer peripheral edge of the stamper into which the protrusion is inserted, and the protrusion and the engagement hole are engaged. On the basis of the,
A mold for a disk base, characterized in that the stamper is prevented from rotating around a center line.