JPH06357B2 - Mold for disk - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a disk molding die used for molding disks such as optical disks and magnetic disks, and more particularly to moving a sprue bush for guiding a resin material into a cavity. However, the present invention relates to a disk molding die capable of punching out a central hole of a disk.

(Prior Art) In a molding die for molding a disc such as an optical disc or a magnetic disc, a resin material is generally injected into a disc molding cavity through a sprue bush arranged in a fixed mold. Then, the male cutter arranged in the movable mold that forms a cavity with the fixed mold is thrust into the female cutter provided in the fixed mold so that the center hole of the disc is punched out. It has become.

By the way, in such a disk molding die, conventionally, the punching operation of the disk by the male cutter has been performed after the cooling and solidification of the resin material. For that reason, conventionally, a sprue bush is provided so as to be movable in the axial direction thereof, and by retracting the sprue bush in the same direction as the projecting direction of the male cutter, the projecting operation of the male cutter is allowed. It was. That is, in the conventional disk molding die, after the resin material is filled in the cavity, after a certain cooling / solidifying period has passed, the male cutter is projected while retracting the sprue bush, The center hole of the disc was punched out.

However, such a conventional center hole punching method has a drawback that the productivity of the disk is reduced by that much because the molding cycle is lengthened by the time required for the protruding operation of the male cutter, and the resin material Since the punching operation of the central hole is performed in the solidified state, there is an inherent problem that the resin on the inner peripheral surface of the central hole is scraped off with a male cutter, and the cut end of the central hole cannot be finished smoothly, which is never preferable. Was hard to say.

Therefore, in recent years, for the purpose of eliminating such conventional problems, the male cutter is thrust into the female cutter under the molten state of the resin material injected into the cavity, and the space between the male cutter and the sprue bush is increased. A molding method is considered in which the resin material is cooled and solidified in a state where the runner portion is blocked from the cavity. According to such a molding method, since the projecting operation of the male cutter can be performed in parallel with the cooling / solidifying operation of the resin material, the molding cycle can be reliably shortened by the time required for the projecting operation of the male cutter. Therefore, the productivity of the disc can be improved accordingly. In addition, the resin material is cooled when the male cutter is thrust into the female cutter.
Since it is solidified, the cut end of the central hole is finished very smoothly.

However, in the molding die used for such a molding method, since the projecting operation of the male cutter is performed in a molten state of the resin material, it is necessary to prevent the resin material from dripping or leaking, and thus the conventional molding method is used. Similar to the mold, simply arranging the sprue bush so that it can move in the axial direction does not allow the sprue bush to retract with the projecting operation of the male cutter, and it does not move with the projecting operation of the male cutter. In order to retreat, there was a problem that a dedicated moving mechanism having a complicated structure for moving the sprue bush in the axial direction had to be provided in the fixed mold.

On the other hand, it is conceivable that the sprue bush is simply fixedly arranged in the fixed mold, but in this case, the runner portion between the male cutter and the sprue bush due to the protruding operation of the male cutter is used. As the volume decreases, the resin pressure inside the runner increases, so the force required to project the male cutter increases, and the drive means for projecting and operating the male cutter inevitably becomes larger. There is such a problem.

(Problem to be Solved) Here, the present invention has been made in view of such a situation, and a problem to be solved is that a male cutter is projected in a molten state of a resin material, and It is a disk molding die that is made by punching out the center hole of the male cutter, without the need to provide a dedicated moving mechanism for moving the sprue bush, that is, without making the fixed die complicated, to operate the male cutter to project. Another object of the present invention is to provide a disk molding die capable of downsizing the driving means.

(Solution) According to the present invention, in order to solve such a problem, a female cutter is provided on a fixed mold in which a sprue bush for guiding a resin material to a disk molding cavity is arranged, A male cutter that forms a predetermined runner portion with the sprue bush in the movable die that forms the cavity with the fixed die and forms an annular gate portion with the female cutter. While the resin material guided through the sprue bush is injected into the cavity through the runner portion and the annular gate portion, the male cutter is inserted into the female cutter and the runner portion is disposed. A disk component designed to substantially punch through the center hole of the disk molded in the cavity by blocking it from the cavity. In the shape die, a center pin is provided on the male cutter with the tip end facing the runner portion, and the center pin is moved backward to the base end side when the male cutter projects toward the female cutter. Or a retreating operation means for allowing the center pin to retreat toward the base end side thereof is provided, and the pressure of the resin material in the runner portion increases due to the protruding operation of the male cutter toward the female cutter side. It was made possible to absorb based on the backward movement of the.

(Operation) According to the forming die having such a configuration, even if the sprue bush is fixedly attached to the fixed die, the pressure increase of the resin material in the runner portion caused by the protruding operation of the male cutter causes the backward movement of the center pin. Since it is absorbed by the male cutter, the projecting force required for the projecting operation of the male cutter can be small. Therefore, the driving means for carrying out the projecting operation of the male cutter can be downsized without complicating the fixed mold. It is possible.

(Examples) In order to more specifically clarify the present invention,
An embodiment will be described in detail with reference to the drawings.

First, in FIG. 1, reference numeral 10 denotes a mirror surface plate of the fixed mold 12, which forms a disc molding cavity 18 between the mirror surface plate 16 of the movable mold 14 and the rear plate 20.
It is attached to the fixed mold body 22 via. Then, it can be attached to the fixed plate of a mold clamping device (not shown) through the fixed mold body 22.

Through holes 24 are formed in the mirror plate 10, the back plate 20, and the fixed mold body 22 of the fixed mold 12 so as to pass through them concentrically with the cavity 18.
A sprue bush 26 for guiding the resin material to the cavity 18 is fixedly arranged in a state of being fitted therein. The sprue bush 26 is disposed with its tip part retracted into the through hole 24 by a predetermined dimension, so that the sprue bush 26 has a recess 28 of a predetermined depth opening to the cavity 18 at the tip thereof. Has been formed. And here, in the opening of the recess 28,
That is, at the opening of the through hole 24 facing the cavity 18,
A female cutter 32 for punching a central hole of the disc is formed in cooperation with a male cutter 44 described later.

On the other hand, the cavity 1 is formed between the fixed mold 12 and the mirror plate 10.
The mirror surface plate 16 of the movable mold 14 forming the
It is attached to the movable mold body 36 via the movable mold body 36, and is attached to the movable plate of the mold clamping device (not shown) via the movable mold body 36.

Here, the inner surface of the mirror plate 16 is penetrated through the mirror plate 16 and the back plate 34 concentrically with the cavity 18, and the inner stamper holder 3
8 are provided, and the inner and outer peripheral edge portions are respectively held by the inner stamper retainer 38 and the outer stamper retainer (not shown), and a stamper 40 having predetermined information engraved therein is provided.
Is provided. And by this, the cavity 1
The stamper 4 for the disk molded in 8
The information engraved at 0 can be transcribed.

Inside the inner stamper retainer 38 that holds the inner peripheral edge of the stamper 40, the inner stamper retainer 38 penetrates the inner stamper retainer 38 axially movably and concentrically.
The stamper 40 (movable mold 1
An ejector sleeve 42 is provided for releasing from 4). Further, a male cutter 44 having the same outer diameter as the inner diameter of the female cutter 32 is disposed so as to penetrate the ejector sleeve 42 concentrically so as to be movable in the axial direction.

In the retracted state, the male cutter 44 forms an annular gate 46 with the female cutter 32 as shown in FIG.
The runner portion 48 between and is communicated with the cavity 18, and the resin material guided through the sprue bush 26 is allowed to flow into the cavity 18, but in the protruding state, As shown in FIG. 2, the tip end of the runner portion 48 is projected into the recess 28, that is, the female cutter 32, so that the runner portion 48 is cut off from the cavity 18 and the runner portions 48 are cut off.
Also, the resin materials in the cavity 18 are prevented from flowing mutually. Then, as will be described later, the resin material is injected into the cavity 18 in the retracted state of the male cutter 44, while the cavity 1 is in the projected state of the male cutter 44.
The resin material injected into 8 is cooled and solidified,
A disc having a punched-out central hole is directly molded. That is, the central hole of the disk is substantially punched out by cooling and solidifying the resin material while the male cutter 44 is held at the protruding position.

The projecting operation and the retracting operation of the male cutter 44 are performed here by a double-acting cylinder (not shown) provided at the base end thereof. Here, the double-acting cylinder provided at the base end portion of the male cutter 44 constitutes a driving means for causing the male cutter 44 to project.

Further, in the figure, 50 is a double-acting ejector cylinder for moving the ejector sleeve 42 in the axial direction.

By the way, in the central portion of the male cutter 44, as shown in FIG. 1, with the tip end surface facing the runner portion 48,
An ejector pin 52 as a center pin is arranged so as to be movable in the axial direction. This ejector pin 52
Double-acting ejector cylinder 5 provided at the base end thereof
The ejector cylinder 54 always holds the ejector cylinder 54 at the forward position on the tip side of the ejector cylinder 54. During processing, when the male cutter 44 is projected from its retracted position and actuated,
Along with the projecting operation of the male cutter 44, the male cutter 44 can be retracted from its advanced position to its proximal retracted position. Then, in a state of being retracted to the retracted position on the base end side, it is drawn into a pin accommodating hole 56 formed in the male cutter 44 by a predetermined dimension.

Then, here, the volume of the runner portion 48 (the volume portion indicated by reference symbol A in FIG. 2) that increases due to the retracting operation of the ejector pin 52 and the volume of the runner portion 48 that decreases due to the projecting operation of the male cutter 44. (In FIG. 2,
The volume increase (denoted by reference numeral B) is made to coincide with each other, and as a result, as described later, the pressure increase caused by the protruding operation of the male cutter 44 on the resin material in the runner portion 48 causes the ejector pin 52 to retract. It is almost completely absorbed by the operation. That is, the resin pressure in the runner portion 48 is made to hardly change by the projecting operation of the male cutter 44.

1 and 2, 58 is an electromagnetic switching valve for switching the forward movement and the backward movement of the ejector pin 52. Here, a switching valve (not shown) for projecting and operating the male cutter 44 is shown. By switching the switching valve 58 in synchronism with the switching operation of the ejector pin 52, the ejector pin 52 is moved backward with the projecting operation of the male cutter 44. Further, as is clear from the above description, here, the ejector cylinder 54 for retracting the ejector pin 52 in response to the projecting operation of the male cutter 44 constitutes a retracting operation means for retracting the center pin. .

Next, the operation of molding a disk using such a molding die will be described.

That is, when molding a disc using such a molding die, first, the ejector sleeve 42 and the male cutter 44 are held at their respective retracted positions, and
The movable mold 14 is matched with the fixed mold 12 in a state where the ejector pin 52 is held at the forward position. Then, in this mold matching state, the resin material is injected into the cavity 18 from the nozzle 60 of the injection device through the sprue bush 26. The resin material injected from the nozzle 60 of the injection device is injected into the cavity 18 through the sprue bush 26, the runner portion 48 and the gate 46.

When a predetermined amount of resin material is filled in the cavity 18 by such a resin material filling operation, the male cutter 44 is started to project by a double-acting cylinder (not shown), and the electromagnetic switching valve 58 is switched to cause ejection of the ejector. The retracting operation of the pin 52 is started, the male cutter 44 is advanced to its projecting position and is projected into the female cutter 32, and the ejector pin 52 is retracted to its retracted position. Then, in this state, the resin material is cooled and solidified.

That is, while the resin material injected into the cavity 18 is still in a molten state, the male cutter 44 projects and operates, and the cavity 18 and the runner portion 48 are shut off from each other. Then, by cooling the resin material in this state, the central hole is punched out, and the disc on which the information of the stamper 40 is transferred and the central hole punched portion which is the resin portion punched from the disc are separated. It is solidified and molded into the body.

Here, as described above, since the volume of the runner portion 48 that is reduced by the projecting operation of the male cutter 44 and the volume of the runner portion 48 that is increased by the retracting operation of the ejector pin 52 are matched, as described above. The pressure increase of the resin material in the runner portion 48 caused by the projecting operation of the male cutter 44 is almost completely absorbed by the retracting operation of the ejector pin 52, and therefore the projecting operation required for the projecting operation of the male cutter 44 is performed. The force will be relatively small.

When the cooling / solidifying period of the resin material elapses, the movable mold 14 moves along with the movement of the movable plate of the mold clamping device.
Then, the disc formed in the cavity 18 and the center hole punched portion cooled in the runner portion 48 and the disk formed in the cavity 18 are released from the fixed die, respectively. After the mold opening operation is completed, the ejector cylinders 50 and 54 are used to eject the ejector sleeve 42 and the ejector pin 5.
2 are respectively ejected, and the disc and the central hole punched portion of the disc are released from the movable mold 14. Then, after the resin in the punched-out portion of the center hole of the disc is removed, the disc is taken out by a predetermined take-out device to form an intended disc, that is, the center hole, and the information of the stamper 40 is transferred. A disc will be obtained.

As described above, in the molding of the disc using the molding die of this embodiment, the male cutter 44 was projected and actuated while the resin material was still in a molten state, and the male cutter 44 was held at the projected position. Since the desired material is molded by cooling and solidifying the resin material in this state, the disk molding is more difficult than when using a conventional molding die in which the center hole of the disk is punched out after the resin material is cooled and solidified. The cycle can be shortened to improve its productivity, and the cut in the center hole of the disk can be finished smoothly.

Then, as described above, when the male cutter 44 is ejected, the ejector pin 52 is interlocked and retracted, and the runner portion 4 caused by the male cutter 44 ejected is operated.
Since the rise of the resin pressure in 8 is satisfactorily avoided, the protruding force required for the protruding operation of the male cutter 44 is small, even though the sprue bush 26 is fixedly arranged in the fixed mold 12. Therefore, the projecting operation of the male cutter 44 is performed by a relatively small double-acting cylinder without complicating the fixed mold 12 by adopting a dedicated moving mechanism for moving the sprue bush 26. It can be done.

As described above, one embodiment of the present invention has been described in detail, but this is a literal example, and the present invention is not limited to such a specific example, within a range not departing from the gist thereof,
It goes without saying that the present invention can be implemented in a mode in which various changes, corrections, and improvements are made.

For example, in the above-described embodiment, the volume change amount of the runner portion 48 due to the projecting operation of the male cutter 44 and the volume change amount of the runner portion 48 due to the retracting operation of the ejector pin 52 as the center pin are made to coincide with each other. It is not always necessary to match them, and it is also possible to set one volume change amount larger than the other volume change amount as necessary.

Further, in the above-described embodiment, the double-acting ejector cylinder 54, which positively moves the ejector pin 52 backward when the male cutter 44 is projected, constitutes the backward movement means. The retreating operation means of (4) does not necessarily have to positively retreat the center pin, but simply allows the retreat of the center pin as the resin pressure in the runner portion increases due to the protruding action of the male cutter. It may be one. In that case, it is possible to apply back pressure, that is, resistance to the center pin.

Furthermore, in the above-described embodiment, the ejector pin for releasing the resin in the punched-out portion of the central hole from the movable mold also serves as the center pin, but the ejector pin and the center pin may be formed as separate members.

(Effects of the Invention) As is apparent from the above description, the mold according to the present invention has the runner associated with the projecting operation of the male cutter during the punching of the disk center hole in the molten state of the resin material by the projecting of the male cutter. Since the rise of resin pressure in the part can be absorbed by the backward movement of the center pin provided on the male cutter without moving the sprue bush, a dedicated moving mechanism for moving the sprue bush is provided. Thus, it is possible to obtain an effect that the driving means for projecting and operating the male cutter, and hence the entire molding die, can be downsized without complicating the fixed mold.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an essential part showing an example of the mold for a disk according to the present invention, and FIG. 2 is a cross-sectional view of the essential part showing a different operating state of the mold of FIG. 12: Fixed mold 14: Movable mold 18: Disc molding cavity 26: Sprue bush 32: Female cutter 44: Male cutter 46: Gate 48: Runner part 52: Ejector pin (center pin) 54: Ejector cylinder (reverse actuation means)

Claims (1)

[Claims] 1. A movable mold for forming a cavity between the fixed mold and a fixed mold, the female mold being provided with a sprue bush for guiding a resin material to the disc molding cavity. , Forming a predetermined runner portion with the sprue bush, and arranging a male cutter forming an annular gate portion with the female cutter,
The resin material guided through the sprue bush is injected into the cavity through the runner portion and the annular gate portion, while the male cutter is inserted into the female cutter to block the runner portion from the cavity. As a result, in the disk molding die in which the central hole of the disk molded in the cavity is substantially punched out, the center pin is arranged on the male cutter with the tip end facing the runner portion, and Retracting operation means is provided for allowing the center pin to retreat toward the base end side in response to the projecting operation of the male cutter toward the female cutter side, or to allow the center pin to retreat toward the base end side. The pressure of the resin material in the runner part is increased due to the projecting operation of the cutter to the female cutter side. A disk molding die characterized in that the center pin can be absorbed based on the backward movement of the center pin.