JPH0628882B2 - Disc molding method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a disk molding method capable of advantageously molding a disk such as an optical disk or a magnetic disk, and particularly to a disk molding method in which maintenance and management of a mold are easy. It is about.

(Background Art) Discs such as optical discs and magnetic discs are usually manufactured by an injection molding method. Then, in the injection molding, a predetermined shape is provided in a donut-shaped cavity formed between the fixed mold and the movable mold through an inner hole of a sprue bush arranged concentrically with the cavity on the fixed mold side. By injecting a resin material, a disc on which predetermined information is transferred is molded in the cavity, while an ejector sleeve arranged on the movable mold side concentrically with the sprue bush is projected to move the disc to the movable position. A structure in which a mold is released from the mold, and an ejector pin arranged in the center of the ejector sleeve is projected to release the sprue resin portion of the disk central hole solidified in the sprue bush from the movable mold. Disc molding dies are commonly used.

Thus, in this type of conventional disc molding die, after the resin in the cavity and the sprue bush is solidified, the male cutter arranged on the movable die side is the female cutter provided on the fixed die side. The center hole of the disc is punched out by being thrust into the inside of the disc, and therefore, the galling phenomenon inevitably occurs between the male cutter and the female cutter. There was a problem that the cutter, especially the male cutter, was easily damaged. In this way, when the male cutter arranged on the movable die side is damaged, it is necessary to spend a lot of time to replace the male cutter with disassembling the movable die. there were.

(Problem to be Solved) Here, the present invention has been made in view of such circumstances, and the problem is that the present invention can be performed without causing galling between a male cutter and a female cutter. It is an object of the present invention to provide a disk molding method which has a long life of the male cutter and is easy to maintain and manage, in which the central hole of the disk can be punched and formed by using the male cutter arranged on the mold side.

(Solution) In order to solve such a problem, in the present invention, as described above, the donut-shaped cavity formed between the fixed mold and the movable mold is concentric with the cavity. By injecting a predetermined resin material through the inner hole of the sprue bush disposed on the stationary mold side, a donut-shaped disc having predetermined information transferred therein is molded in the cavity, while concentric with the sprue bush. The ejector sleeve disposed on the movable die is ejected, the disc is released from the movable die, and the ejector pin disposed on the center of the ejector sleeve is ejected to solidify in the sprue bush. In the disk molding method, in which the sprue resin portion of the central hole of the disk is released from the movable mold, The sprue bush is disposed with its tip always protruding toward the cavity, and between the ejector sleeve and the ejector pin,
A male cutter having a function of holding a sprue resin portion of the disc center hole and having the same outer diameter as the sprue bush is set back to form an annular gate having a predetermined gap with the sprue bush at the time of forming the cavity. Movably provided between a position and an advanced position that can substantially abut the sprue bush, and further, the male cutter is moved from the retracted position to the male cutter against the pressure of the resin material injected into the cavity. After the resin material has been injected by providing a cutter pushing means capable of advancing to a position where it substantially comes into contact with the sprue bush, the male material is pushed by the cutter pushing means while the resin material is still in a fluid state. Move the cutter to the forward position and allow the resin material to cool and solidify to prevent the ejector sleeve from protruding the disc. At the same time, the film-shaped resin connecting portion formed between the facing surfaces between the male cutter and the sprue bush is cut by the ejector sleeve to separate the disc from the sprue resin portion. It was decided.

Here, the position where the male cutter substantially contacts the sprue bush means that the resin solidified between the facing surfaces is such that the male cutter can be easily cut by the ejecting operation of the ejector sleeve. The position near the sprue bush.

(Operation / Effect) In such a disk molding method, after the resin material is injected into the cavity, the male cutter is substantially attached to the sprue bush by the cutter pushing means while the resin material is still in a fluid state. After the resin material is solidified in that state, the mold is opened, and the ejector sleeve is projected and operated to punch out the central hole of the disk.

That is, if the disk molding method according to the present invention is adopted,
Using a male cutter arranged on the movable mold side without thrusting the male cutter into the female cutter like a conventional disc molding mold, that is, without causing a galling phenomenon between the male cutter and the female cutter. It is possible to punch out the center hole of the disc, and therefore, it is possible to prevent the male cutter due to such a galling phenomenon from being damaged well, and to greatly reduce the frequency of troublesome replacement of the male cutter. The maintenance and management of the mold can be significantly facilitated.

Further, according to the disk molding method of the present invention, the pole between the facing surfaces of the male cutter and the sprue bush that connects the disk solidified in the cavity and the sprue resin portion of the disk central hole solidified in the sprue bush is connected. The central hole of the disc can be punched out by simply cutting the thin resin joint by ejecting the ejector sleeve, so that the inner surface of the center hole of the disc can be finished smoothly, and when using a conventional die It is possible to eliminate the burrs formed on the edge portion of the central hole in the axial direction as shown in FIG. 8 and to obtain an effect that the cut end of the central hole of the disk can be greatly improved.

(Example) Hereinafter, one example of the present invention will be described in detail with reference to the drawings.

First, in FIG. 1, a disk mold according to the present invention in a state where a fixed mold 10 and a movable mold 12 are matched with each other and a donut-shaped cavity 14 is formed between the molds 10 and 12. The cross section of the main part of the mold is schematically shown.
There, 16 is a sprue bush for guiding a predetermined resin material into the cavity 14, and is fixedly disposed in the fixed mold 10 concentrically with the cavity 14. As is clear from the figure, here, the outer peripheral surface of the sprue bush 16 substantially defines the inner peripheral surface of the cavity 14, in other words, the cavity 14
A central hole 20 of a disk 18 to be described later that is solidified and molded inside
The fixed mold 1 in which the tip portion of the sprue bush 16 forms the cavity 14 so as to substantially define (see FIG. 4)
It is made to protrude from the cavity forming surface of 0 by a predetermined dimension.

On the other hand, in FIG. 1, reference numeral 22 is an ejector sleeve for releasing a disc 18 to be described later, which is molded in the cavity 14, from the movable mold 12, and the sprue bush 16 disposed on the fixed mold 10 Has the same inner diameter as the outer diameter of the movable mold 12 and has a retracted position in which the front end surface is flush with the cavity forming surface of the movable mold 12, and the front end surface protrudes from the retracted position toward the fixed mold 10 side with a predetermined size. It can be moved in the axial direction by a similar ejector sleeve moving means (not shown) of the related art.

The movement stroke of the ejector sleeve 22 by the ejector sleeve moving means is set to be larger than the movement stroke of the male cutter 24 described later by a predetermined amount.

On the inner peripheral surface of the ejector sleeve 22, a retracted position (retracted position) where the tip end surface is flush with the tip end surface of the ejector sleeve 22 at the retracted position, and the cavity 1
4 in the formed state (the die 10 and 12 mating state), the sprue bush 16 and the sprue bush 16 are movable so as to move between the sprue bush 16 and the protruding position (advancing position) that can substantially abut the tip surface. A male cutter 24 having the same outer diameter is arranged so as to be movable in the axial direction, and a male cutter 24 for moving the male cutter 24 is provided at a base end portion of the male cutter 24 between the retracted position and the protruding position. A return cylinder (not shown) is provided. Then, the male cutter 24 is held in the retracted position by the returning cylinder when the resin material 38 described later is injected into the cavity 14 through the inner hole of the sprue bush 16, and the tip surface of the sprue bush 16 is held. An annular gate 26 with a predetermined gap between
While the resin material 38 is formed (see FIG. 1), after the injection of the resin material into the cavity 14 is completed, the resin material 38
Is still in a flowable state, the sprue bushing 16 is advanced by the returning cylinder.
(See FIG. 2), so that the inner peripheral surface of the cavity 14, in other words, the disk 18 described later.
Of the center hole 20 of the sprue bushing 16 is substantially defined. In addition, the resin at the position of the gate 26 where the male cutter 24 is advanced and eliminated in this way is
The surrounding resin is compressed and absorbed. That is, as the male cutter 24 advances, the resin pushed out flows into the cavity 14 side and the sprue bush 16 inner hole side, and compresses the resin present therein. This compression margin is generally very small because the gate thickness is generally only 0.1 to 0.4 mm to 0.1 mm or less, and the portion that flows into the cavity 14 side is a film-like resin layer. The number is even smaller because it has to pass 40. Most of the compression allowance is absorbed by the sprue resin 32 and only increases its internal pressure, which has little effect on the product (disk).

A through hole 28 is formed in the male cutter 24 so as to penetrate the center thereof in the axial direction. The through hole 28 is fitted in the through hole 28 so as to be slidable in the axial direction and the ejector pin 30 is disposed. Has been done. The male cutter 22 is located at the base end of the ejector pin 30 and is in the retracted position.
Of the male cutter 22 at a retracted position (see FIG. 1) in which the tip surface is drawn into the through hole 28 with a predetermined dimension from the tip surface of the male cutter 22, and the tip surface is closer to the fixed mold 10 side than the tip surface of the male cutter 22 at the protruding position. Ejector pin moving means (not shown) similar to the conventional one for moving the ejector pin 30 between the protruding position (see FIG. 5) that projects is provided, and as will be described later, by such ejector pin moving means. A disk central hole 20 described later is solidified in the sprue bush 16 by the ejecting operation of the ejector pin 30.
The sprue resin 32 (see FIG. 4), which is the resin portion of
It can be released from the fixed mold 10.

Here, as shown in FIG. 1, in the through hole 28 formed in the male cutter 24, the sprue resin 32 is located at a portion that defines the molding space of the sprue resin 32.
A circumferential annular groove 34 having an undercut shape with respect to the pull-out direction is formed. As a result, as will be described later, during the mold opening operation of the molds 10 and 12,
Also, during the ejecting operation of the ejector sleeve 22 prior to the ejecting operation of the ejector pin 30, the sprue resin 32 solidified in the sprue bushing 16 is engaged with the annular groove 34 of the through hole 28 so that the male cutter 2
It is designed to be held at 4.

Next, the operation of molding the disk 18 using such a mold will be described.

That is, in the injection molding of the disk 18 using such a mold, first, the ejector sleeve 22, the ejector pin 30, and the male cutter 24 are retracted to their respective retracted positions by their corresponding moving means and return cylinders. The movable mold 12 is matched with the fixed mold 10 in the state of being held. And by doing this, those molds 1
A cavity 14 is formed between 0 and 12, and an annular gate 26 having a predetermined gap (usually about 0.1 to 0.4 mm) is formed between the sprue bush 16 and the male cutter 24.

When the movable mold 12 is fitted to the fixed mold 10 to form the cavity 14 and the gate 26, the injection nozzle 3 that is nozzle-touched by the sprue bush 16 in this state.
6, the inner hole of the sprue bush 16 and the gate 26
Through, the predetermined resin material 38 is injected into the cavity 14 (see FIG. 1). Then, when the injection operation of the resin material 38 into the cavity 14 is completed, the male cutter 24 is not shown in the return cylinder at the time when the injection holding is completed or before and after the injection holding is completed. The sprue bush 16 is operated by projecting at
To substantially abut (see FIG. 2).

That is, even if the male cutter 24 is the sprue bush 1
It is difficult to completely crush the resin material 38 located between the sprue bush 16 and the sprue bush 16, even if the sprue bush 16 and the male cutter 24 have a stroke capable of coming into contact with the sprue bush 16. As shown in FIG. 2, an extremely thin film-like resin layer 40 having a thickness of about 0.1 mm or less, which can be easily cut by ejecting operation of an ejector sleeve 22 described later, is formed. . In this sense, the forward movement of the return cylinder causes the male cutter 24 to substantially abut the sprue bush 16.

As is clear from the above description, here, the return cylinder (not shown) provided at the base end portion of the male cutter 24 constitutes a cutter pushing-out means for moving the male cutter 24 forward.

When the male cutter 24 is substantially brought into contact with the sprue bush 16, the resin material 38 in the cavity 14 and the sprue bush 16 is cooled and solidified in that state. Then, when the resin material 38 in the cavity 14 and the sprue bush 16 is solidified after the preset cooling / solidifying period has elapsed, the movable mold 12 is fixed to the fixed mold 1.
The mold 18 is opened from 0, and the disk 18 solidified in the cavity 14 and the sprue resin 32 solidified in the sprue bush 16 are released from the fixed mold 10.

On the cavity forming surface on the movable mold 10 side, a stamper (not shown) in which predetermined information is engraved is arranged as in the conventional disk molding mold.
Information of the stamper is transferred to the disk 18 molded therein by the solidifying action of the resin material 38.

When the molds 10 and 12 are opened, as shown in FIG. 3, a suction pad 42 for sucking the disk 18 between the molds 10 and 12 and a sprue for gripping the sprue resin 32. The chuck 44 is inserted. And
As shown in FIG. 4, first, only the suction pad 42 is sucked onto the disk 18.

When the suction pad 42 is sucked onto the disc 18, the ejector sleeve moving means (not shown)
The ejector sleeve 22 is projected from the retracted position to the projected position, the disc 18 is released from the movable mold 12 (stamper), and the central hole 20 of the disc 18 is punched out by the release operation of the disc 18. To be

That is, the disc 18 solidified in the cavity 14 and the sprue resin 32 solidified in the sprue bush 16 that are ejected by the ejecting operation of the ejector sleeve 22 are, as described above, the sprue bush 16 and the male cutter. Very thin resin layer 40 between 24
The sprue resin 32 solidified in the sprue bushing 16 is only connected by the resin connecting portion 46 which is a solidified portion of the male sprue bushing 16 (see FIG. 3). Since the male cutter 24 is held as it is by the engagement with the annular groove 34 formed in the above, by the releasing operation of the disc 18 from the movable mold 12,
As shown in FIG. 4, the ejector sleeve 22
The sprue resin 32 solidified therein is very easily cut from the disc 18 at the outer peripheral edge of the resin connecting portion 46, so that the central hole 20 of the disc 18 is punched out.

When the disk 18 is released from the movable mold 12 by the ejecting operation of the ejector sleeve 22 and the central hole 20 of the disk 18 is punched out, the ejector pin 30 is then ejected as shown in FIG. The sprue resin 32 is separated from the male cutter 24 by being ejected from the retracted position to the protruding position by the pin 30 moving means, and separated from the movable mold 12. Then, in that state, the sprue resin 32 is grasped by the sprue chuck 44, and in the grasped state, after the ejector sleeve 22, the ejector pin 30 and the male cutter 24 are retracted to their respective retracted positions (see FIG. 6), Adsorption pad 42
And the sprue chuck 44 is pulled out from between the molds 10 and 12, and the disk 18 and the sprue resin 32 are taken out of the mold. Then, first, the gripped state of the sprue resin 32 is released and the sprue resin 32 is dropped and accommodated in a predetermined container, and then the disc 18 is transferred to a predetermined stocker to complete a series of molding cycles. That is, the disc 18 having the central hole 20 in which the information of the stamper is transferred to one side can be obtained.

Thus, when molding the disk 18 using the mold of this embodiment, as described above, the male cutter 24 is operated by the male cutter 24 while the resin material 38 is still flowable.
6, the male cutter 24 and the sprue bush 16 are brought as close as possible to each other so that the male cutter 24 and the sprue bush 16 are made as close to each other as possible, and an extremely thin resin layer 40 is formed between their facing surfaces. 38 is cooled and solidified, then
When the disc 18 is released from the movable mold 12 by the ejecting operation of the ejector sleeve 22, the resin connecting portion 46, which is the solidified portion of the resin layer 40, is cut at its outer peripheral edge portion, and the central hole 20 of the disc 18 is formed. Since it is formed by punching, unlike the conventional mold, the male cutter 24 does not plunge into the female cutter to cause a galling phenomenon, and the male cutter 24 is caused by such a galling phenomenon. The cutter 24 is not damaged. That is, the frequency of damage to the male cutter 24 is reduced by the amount that does not cause galling with the female cutter. Therefore, the frequency of replacement of the male cutter 24 is reduced by that amount, and maintenance of the mold is reduced. It will be easy to manage.

When molding the disk 18 using the mold of this embodiment, the extremely thin film-like resin connecting portion 46 solidified between the facing surfaces of the male cutter 24 and the sprue bush 16 as described above is used. When the disc 18 is released from the movable mold 12, the disc 18 is simply cut at its outer peripheral edge portion.
Since the central hole 20 of the
The cut end of 0 is extremely smooth, and as shown in FIG. 7, the burrs formed on the axial end edge of the central hole of the disk when the conventional mold is used (see FIG. 8). Formation is avoided and, therefore, compared to disks molded using conventional molds,
A disc 18 having a central hole 20 with a significantly improved cut state is obtained.

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, and various changes and modifications are made without departing from the spirit of the present invention. Of course, it can be implemented in a modified form.

For example, in the above-mentioned embodiment, the cutter pushing-out means for moving the male cutter 24 forward is constituted by the returning cylinder for moving the male cutter 24 forward and backward.
While the cutter pushing-out means is composed of a simple protruding means such as a single-acting cylinder, the male cutter 24 is returned to the retracted position by a biasing means such as a spring or the sprue bush 16
It is also possible to use the resin pressure of the resin material 38 injected therein.

Also, the protruding position of the male cutter 24 is
Is preferably in contact with or substantially in contact with the sprue bush 16, but the male cutter 2 is slightly forward of the position in which the sprue bush 16 is exactly in contact.
It is also possible to set the protruding position of 4.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing a main part of an example of a mold used in a disk molding method according to the present invention, and FIG. 2 shows a protruding state of a male cutter of the mold of FIG. First
FIG. 3 is a view corresponding to the drawing, and FIG. 3 is a view showing a movable mold of the mold of FIG. 1 together with a suction pad and a sprue chuck inserted between a fixed mold and a movable mold. FIG. 4 is a corresponding view, FIG. 4 is a view corresponding to FIG. 1 showing a movable mold of the mold shown in FIG. 1 in a releasing state of a disk, and FIG. 5 is a mold shown in FIG. It is a figure corresponding to FIG. 1 which shows the movable metal mold | die in the mold release state of a sprue resin,
FIG. 6 is a view corresponding to FIG. 1 showing the movable mold of the mold of FIG. 1 immediately before the disk and the sprue resin are taken out of the mold, and FIG. FIG. 6 is a cross-sectional view of a main part for explaining a formation state of a central hole of a disc molded using the mold of FIG. FIG. 8 is a view corresponding to FIG. 7 of a disk molded by using a conventional mold. 10: Fixed mold, 12: Movable mold 14: Cavity, 16: Sprue bush 18: Disc, 20: Central hole 22: Ejector sleeve, 24: Male cutter 26: Gate, 30: Ejector pin 32: Sprue resin, 34 : Annular groove 46: Resin connection part

Claims (1)

[Claims] 1. A predetermined resin material is provided in a donut-shaped cavity formed between a fixed mold and a movable mold through an inner hole of a sprue bush concentrically arranged on the fixed mold side. By injecting, a doughnut-shaped disc to which predetermined information is transferred is molded in the cavity, while an ejector sleeve arranged on the movable mold concentrically with the sprue bush is projected to move the disc to the movable position. A disk which is released from the mold and projects an ejector pin arranged in the center of the ejector sleeve to release the sprue resin portion of the disk center hole solidified in the sprue bush from the movable mold. In the molding method, the tip of the sprue bush is always protruded toward the cavity side with respect to the fixed mold. A male cutter having the same outer diameter as that of the sprue bush and having a function of holding the sprue resin portion of the disc center hole between the ejector sleeve and the ejector pin. At the time, it is provided so as to be movable between a retracted position forming an annular gate having a predetermined gap with the sprue bush and an advanced position capable of substantially contacting the sprue bush, and further injected into the cavity. A cutter pushing means capable of advancing the male cutter from the retracted position to a position where it substantially abuts the sprue bush is provided against the pressure of the resin material, and the resin material is injected after the resin material is injected. While the material is still in a fluidized state, move the male cutter to the advanced position by the cutter pushing means, The resin material is cooled and solidified to eject the disc by the ejector sleeve, and the film-shaped resin connecting portion formed between the facing surfaces between the male cutter and the sprue bush is attached to the ejector. A disk molding method comprising cutting with a sleeve to separate the disk from the sprue resin portion.