JPH0375330B2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a mold for a disk base, and particularly to an injection compression mold.
The present invention relates to a disk base mold suitable for use in molding.

(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, a fixed mold and a movable mold each having a structure in which a mirror plate is disposed on the mold body are matched, and a cavity is formed between the mirror plate of both molds. By injecting a predetermined resin material into the cavity through a sprue bush disposed through the fixed mold, the information of the stamper disposed on the mirror plate of the movable mold was transferred. A mold designed to mold the disk base is used.

By the way, when injection molding a disk substrate, a so-called injection compression molding method is generally employed because it is possible to obtain a disk substrate of superior quality than a normal injection molding method. In other words, in this injection compression molding method, when the resin material is injected into the cavity, the mirror plate on the fixed mold side and the mirror plate on the movable mold side are opened by a predetermined dimension larger than the molded thickness of the disk base. After the resin material is injected into the cavity, the mirror plate is brought close to the molding thickness of the disk base to fill the cavity with the resin material and mold the disk base, which is different from the normal injection molding method. Compared to the case where this method is adopted, it is possible to significantly suppress the internal stress in the molded disk base, and furthermore, the occurrence of birefringence caused by the internal stress. Therefore, it is possible to obtain a disk base of superior quality and with lower birefringence than when a normal injection molding method is used.

(Problem) However, in the above-mentioned conventional disk base mold used for such injection compression molding, the mirror plates of the fixed mold and the movable mold are both fixedly arranged with respect to the mold body. The pressure of the resin material injected into the cavity overcomes the clamping pressure from the clamping cylinder and moves the movable mold backward, making the distance between both mirror plates larger than the molded thickness of the disk base. As a result, variations in the hydraulic pressure of the clamping cylinder due to temperature changes, etc., can cause variations in the spread distance between the mirror plates and, in turn, in the amount of resin material injected into the cavity. However, there was a problem with variations in the quality of the molded disk base.

(Solution Means) Against this background, the present invention has been made in order to provide a mold for a disk base suitable for use in injection compression molding, which can satisfactorily eliminate the above-mentioned problems. The gist of this is that, as mentioned above, a fixed mold and a movable mold each having a structure in which a mirror plate is disposed on the mold body are matched, and the mirror plate of both molds is molded together. A stamper disposed on the mirror plate of the movable mold is formed by forming a cavity between the fixed mold and injecting a predetermined resin material into the cavity through a sprue bush disposed through the fixed mold. In a mold for a disk base, which is configured to mold a disk base onto which the information of In this state, the mirror plate of the fixed mold is moved with respect to the mold body of the fixed mold between a molding position that defines the thickness of the disk base and a retracted position that is retreated a predetermined distance from the molding position. The present invention is characterized in that a cylinder means is provided for moving the mirror plate of the fixed mold between the molding position and the retracted position.

(Function/Effect) According to the disk base forming mold having such a structure, when the mold body of the fixed mold and the mold body of the movable mold are in contact with each other, there is no damage inside the cavity. When the resin material is injected and the injection of the resin material is completed, the mirror plate of the fixed mold is moved to its retracted position. By moving the face plate to its molding position using cylinder means and filling the cavity with resin material, the disk base can be injection compression molded in the same manner as when using a conventional mold. In other words, compared to when molded using normal injection molding methods,
This allows you to obtain a disk base of excellent quality.

By the way, in the mold according to the present invention, as described above, when the mold bodies of the fixed mold and the mold body of the movable mold are brought into contact with each other,
The mirror plate of the fixed mold is only movable between the molding position of the disk base and the retracted position. Since the resin material cannot be moved back, if the resin material is injected into the cavity while the molds are aligned as described above, the mirror of both molds will be fixed when the resin material injection is completed. The amount of expansion from the disk molding distance between the face plates, and ultimately the amount of resin material injected into the cavity, is a constant size corresponding to the movement stroke of the mirror plate of the fixed mold when the two molds are matched. Therefore, the setting will always be stable.

In other words, if injection compression molding of a disk substrate is performed using the mold for disk substrates according to the present invention, the hydraulic pressure of the pressing cylinder for pressing the movable mold against the fixed mold may vary. However, it is possible to effectively prevent variations in the amount of resin material injected into the cavity.Therefore, it is possible to effectively prevent variations in the amount of resin material injected into the cavity. This makes it possible to stably obtain disk substrates of superior quality compared to the case of conventional methods.

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

First, in FIG. 1, 10 is a movable mold 12.
This mirror plate forms a disk-shaped disk molding cavity with the mirror plate 16 of the fixed mold 14, and the mirror plate has cylindrical and annular inner and outer stamper holding members 18, 20. A donut-shaped stamper 22 with predetermined information engraved thereon is disposed with the inner and outer peripheral edges held by the stampers.

The mirror plate 10 on the movable side, on which the stamper 22 is disposed, is fixed to a movable mold body 28 via a back plate 24 and an intermediate plate 26, and is further connected to a movable mold body 28 via the movable mold body 28. It is fixedly installed at 30. As a result, the mirror plate 10 and the movable mold body 28 are moved integrally with the movable platen 30 based on the operation of a clamping cylinder (not shown).

Here, the mirror plate 10 is housed in a recess 32 formed in the rear plate 24, and the rear plate 24 and the intermediate plate 26 that hold the mirror plate 10 are mounted on movable metal plates. The mold body 28 is housed in a recess 34 formed in the mold body 28 . Then, a fixed mold body 3, which will be described later,
An annular tapered surface 40 is formed which taper-fits with the tapered surface 38 of 6, and the approach distance of the fixed side mirror plate 16 to the open end surface of the recess 32 of the back plate 24, that is, the formation of the disk base. An adjustable ring 44 for defining the thickness is removably bolted. As is clear from FIG. 1, this adjustable ring 44 has its inner and outer circumferential surfaces fitted into the outer circumferential surface of the outer stamper holding member 20 and the inner circumferential surface of the recess 34 of the movable mold body 28, respectively. In the fitted state, the movable metal fitting body 28 is disposed with its distal end surface slightly recessed inside the recess 34 than the open end surface of the recess 34 of the movable metal fitting main body 28.

Further, as shown in FIG. 1, an ejector sleeve 46 is disposed in the movable mold 12 and is slidably fitted to the inner peripheral surface of the inner stand bar holding member 18. An ejector cylinder 48 provided at the base end of the ejector sleeve 46 allows the distal end of the ejector sleeve 46 to protrude toward the cavity by a predetermined distance. and,
Penetrating the movable mold 12 while being slidably fitted to the inner peripheral surface of the ejector sleeve 46,
A hollow punch cutter 50 is provided for punching a center hole in the disk base, and an ejector pin 52 is provided to be slidably fitted into the hollow portion of the punch cutter 50 and protrude to the cavity side by a predetermined distance. has been done.

Here, the punch cutter 50 can be moved by a predetermined distance toward the shaving side by the protruding action of an ejecting rod 54 provided through the movable platen 30, and the ejector pin 52 is An ejector cylinder 56 provided at the base end allows it to protrude toward the cavity.

On the other hand, the mirror plate 16 of the fixed mold 14 that forms a cavity with the mirror plate 10 of the movable mold 12 is
Similar to the movable mold 12, a fixed mold is fixed to the back plate 58 while being housed in a recess 60 formed in the back plate 58, and is fixed to the fixed plate 62 via the back plate 58. However, in the fixed mold 14, unlike the movable mold 12, the back plate 58 is not fixed to the fixed mold main body 36, but is attached to the fixed mold main body 36. 36, and is slidably fitted into a recess 66 formed in 36. Here, a plurality of cylinders 68 as cylinder means are located at a portion of the fixed mold body 36 corresponding to the outer peripheral portion of the back panel 58.
are provided at equal intervals in the circumferential direction, and piston rods 70 extending from the pistons 69 of these cylinders 68 are connected to the back surface of the back plate 58 at their tips. Based on the operation of 68,
The back of the back plate 58 is fixed to the recess 66 of the mold body 36
The mirror plate 16
is moved in the direction of its centerline, that is, in the direction of the centerline of the disk molding cavity.

Here, the opening end surface of the recess 66 of the fixed mold body 36 has the movable mold body 28 as described above.
A tapered surface 3 having a shape that taper-fits with the tapered surface 40 of
8 is formed, so that when the molds 12 and 14 are matched in which the movable mold body 28 is brought into contact with the fixed mold body 36, the taper fitting of the tapered surfaces 38 and 40 is performed. Based on this, the fixed mold 14 and the movable mold 12 are aligned, and furthermore, the mirror plate 16 on the fixed side and the mirror plate 10 on the movable side are aligned.

Further, here, the recess 66 of the fixed mold body 36 is formed concentrically with the same diameter as the recess 34 of the movable mold body 28, and both the tapered surfaces 38, 40 are fitted with a taper. When the molds 12 and 14 are in a mating state, the inner surfaces of the recesses 66 and 34 form smooth cylindrical surfaces. In this embodiment, when the fixed mold body 36 and the movable mold body 28 are brought into contact with each other and the molds 12 and 14 are aligned, the back of the fixed side that holds the mirror plate 16 is The face plate 58 is movable while sliding smoothly on the inner surfaces of the recesses 66 and 34, and based on the operation of the cylinder 68, the back surface of the back plate 58 moves into the recess 66 of the fixed mold body 36. The mirror plate 16 smoothly moves between the position where it abuts the bottom wall of the rear plate 58 and the position where the open end face of the recess 60 of the back plate 58 abuts the tip face of the adjustable ring 44 on the movable mold 12 side. They are now being forced to move.

In addition, as is clear from FIG. 1, the back plate 58
is the piston rod 70 of the cylinder 68 whose back surface abuts the bottom wall of the recess 66 of the fixed mold body 36.
When the recess 60 is retracted, the opening end surface of the recess 60 is flush with the opening end surface of the recess 66 of the fixed mold body 36, or is slightly retracted to the inside of the recess 66. Furthermore, as is clear from FIG. 1, the cylinder stroke of the cylinder 68,
That is, the amount of protrusion of the piston rod 70 from the retracted position is defined as the movement stroke of the mirror plate 16 when the molds 12 and 14 are matched:
It is set sufficiently larger than α (see FIG. 1).

In this embodiment, such a fixed mold 1 is used.
4, the proximal end is fixedly held by the stationary mold body 36 while slidably penetrating the center portions of the mirror plate 16 and the back plate 58, and the outer diameter of the tip portion is adjusted to the outer diameter of the punch cutter 50. A sprue bush 72 with a diameter and an inner diameter is disposed coaxially with the punch cutter 50, and is in a cavity formed between the mirror plate 16 of the solid mold 14 and the mirror plate 10 of the movable mold 12. A predetermined resin material is injected from a nozzle 74 of a heating cylinder of an injection device through this sprue bush 72.

Next, the operation when injection compression molding a disk base using such a mold will be explained.

That is, when performing injection compression molding of a disk base using the mold of this embodiment, first, the piston rod 70 of the cylinder 68 is retracted, and the back surface of the back plate 58 is placed in the recess 66 of the fixed mold body 36. The fixed side mirror plate 16 is moved to the retracted position where it contacts the bottom wall. Then, in this state, the clamping cylinder is operated, and the movable mold 12 is matched to the fixed mold 14. In other words, the movable mold body 2
8 is brought into contact with the fixed mold body 36. As shown in FIG. 1, in this mold matching state, a predetermined resin material is inserted through the sprue bush 72 into the cavity formed between the fixed side mirror plate 16 and the movable side mirror plate 10. 76 is ejected. Note that the working oil pressure of the compression cylinder is set to be sufficiently large during the injection operation of the resin material 76, and during this time, the mold matching state between the fixed mold 14 and the movable mold 12 is maintained. Furthermore, the fixed side mirror plate 16 is held in its retracted position by the cylinder 68 during this injection operation of the resin material 76. In this way, regardless of slight fluctuations in the clamping force of the movable mold 12 against the fixed mold 14, and even slight fluctuations in the hydraulic pressure of the clamping cylinder,
Both mirrored plates 1 at the time of completion of injection of resin material 76
The amount of expansion from the disk molding distance (disk molding thickness) between 0 and 16 is always set to a constant size: α, so that a stable amount of resin material 76 is always injected into the cavity. They are forced to do so.

Once the injection operation of the resin material 76 into the cavity is completed, the cylinders 68 are then actuated to eject their piston rods 70 into the recesses 6 of the back plate 58, as shown in FIG.
The fixed side mirror plate 16 is advanced by a distance α from the retreated position to a forming position where the opening end face of the movable mold 12 contacts the tip face of the adjustable ring 44 on the movable mold 12 side. And this fixed side mirror plate 1
6 forward operation (compression operation),
A resin material 76 is filled into the cavity. In addition, at the time of such compression operation, based on the fitting between the tapered surface 40 of the movable mold body 28 and the tapered surface 38 of the fixed mold body 36,
Since both molds 12 and 14 are maintained in a core-insulating state,
The fixed side mirror plate 16 can be smoothly moved forward according to the operation of the cylinder 68 without causing galling with the movable mold body 28.

Immediately after such compression operation is completed, or after a certain cooling period,
The piston rod 70 of the cylinder 68 is further protruded, and as shown in FIG. The mold is opened.
Then, based on this mold opening operation, the sprue bush 72 is moved backward by the mold opening amount β, and the sprue bush 72 is released from the molded product 78. Thereafter, as shown in FIG. 4, the punch cutter 50 is pushed out toward the cavity side by the projecting rod 54, and the gate portion of the molded product 78, that is, the center hole 82 of the disk base 80 is punched out. The mold opening operation described above can be easily performed, for example, by switching the hydraulic pressure of the clamping cylinder from a high pressure to a low pressure while maintaining the hydraulic pressure of the cylinder 68 at the compression hydraulic pressure.

After punching out the center hole 82 of the disk base 80, the molds 12 and 14 are opened as the movable platen 30 moves, as shown in FIG. 48,56
Based on the operation, the ejector sleeve 46 and the ejector pin 52 are respectively projected toward their distal ends, and the disk base 80 and the resin 84 in the central hole punched portion are released from the mold. By taking out the released disk base 80 with a predetermined take-out device, a target disk base 80 is obtained.
is obtained.

As described above, if the mold of this embodiment is used, by operating the cylinder 68 after injecting the resin material 76 into the cavity and advancing the fixed side mirror plate 16 from its retreated position to the molding position, The target disc base 80 can be molded by injection compression molding, and the internal stress and birefringence are smaller than when the disc base 80 is molded by normal injection molding. Therefore, it is possible to obtain a disk substrate 80 of excellent quality.

Moreover, according to the mold of this embodiment, as described above, both the movable side and fixed side mirror plates 10,
The amount of expansion from the disk molding thickness of 16 is always set to a constant size: α regardless of slight fluctuations in the hydraulic pressure of the tightening cylinder, so that the amount of resin material 76 injected into the cavity is always constant. Since the amount is stable at a certain level, it is possible to obtain a disk substrate 80 of excellent quality in an extremely stable manner compared to the case where the disk substrate 80 is injection compression molded using a conventional mold.

In addition, in this embodiment, as described above, the adjustable ring 44 for defining the molding position of the fixed side mirror plate 16 is removably disposed on the movable side back plate 24. By replacing the adjustable ring 44, the thickness of the disk base 80 can be adjusted or changed very easily. Subsequently, the mold release operation of the sprue bush 72 and the ejecting operation of the punch cutter 50 can be performed continuously, which has the advantage that the molding cycle of the disk base 80 can be advantageously shortened. be.

Although one embodiment of the present invention has been described in detail above,
This is a literal example, and it goes without saying that the present invention should not be construed as being limited to this specific example.

For example, in the above embodiment, the cylinder 68 as cylinder means was provided in the fixed mold body 36, but the fixed platen 62 including the cylinder 68
It is also possible to provide it.

Further, in the above embodiment, in order to continuously shift to the gate cutting process (center hole punching process) after the compression operation, the moving stroke of the cylinder 68 as the cylinder means is adjusted to the fixed side mirror plate 16 in the mold matching state. The movement stroke: α is set larger than α, but it is also possible to adopt a configuration in which these movement strokes are made to match.

Further, in the embodiment described above, the resin material 76 is injected into the cavity while the fixed side mirror plate 16 is moved to the retreated position that is set back by α from the molding position. ,
With the fixed mirror plate 16 moved to its molding position, the resin material 76 is injected into the cavity, and the resin material 7 injected into the cavity is
It is also possible to retract the fixed side mirror plate 16 to its retracted position by the pressure of 6, and perform the subsequent compression operation. Even in this manner, it is possible to stably mold the disk base 80 of superior quality compared to the case where injection compression molding is performed using a conventional mold.

In addition, although it is omitted to list specific examples one by one, within the scope of the present invention without departing from the spirit thereof,
Various modifications based on the knowledge of those skilled in the art,
Things that can be implemented with modifications, improvements, etc. are:
It goes without saying.

[Brief explanation of drawings]

FIG. 1 is a front sectional view showing an example of a mold for a disk base according to the present invention, and FIG.
Each figure is an explanatory cross-sectional view for explaining the operation when injection compression molding a disk base using the mold shown in FIG. 1. 10, 16: Mirror plate, 12: Movable mold, 14:
Fixed mold, 22: Stamper, 24, 58: Back plate, 28: Movable mold body, 30: Movable plate, 36:
Fixed mold body, 44: Adjustable ring, 6
2: Fixed plate, 68: Cylinder (cylinder means),
72: Sprue bush, 80: Disk base.

Claims (1)

[Claims] 1. A fixed mold and a movable mold each having a structure in which a mirror plate is disposed on the mold body are matched, and a cavity is formed between the mirror plates of both molds, By injecting a predetermined resin material into the cavity through a sprue bush disposed through the fixed mold, a disk onto which information from a stamper disposed on the mirror plate of the movable mold is transferred is created. In a disk base molding mold for molding a base, when the mold bodies of the fixed mold and the movable mold are in a mating state where the mold bodies of the movable mold are brought into contact with each other, the fixed mold a mirror plate is disposed movably with respect to the mold body of the fixed mold between a molding position that defines the thickness of the disk base and a retracted position that is retreated a predetermined distance from the molding position, and A mold for a disk base, characterized in that a cylinder means is provided for moving the mirror plate of the fixed mold between the molding position and the retracted position.