JP2003103576A - Mold assembly for injection-molding disc base and method for injection-molding disc base - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a sectional pattern which is a part of a movable half of a mold to be moved backward during injecting a synthetic resin, in a process to injection-mold an optical disc base using a toggle mechanism which moves the movable half to a cavity side half. SOLUTION: A set cavity is formed of the sectional pattern 3B elastically supported with a specified space left to a mold base 3A fixed to a movable platen 2 mounted through the toggle mechanism 1 and the movable platen 2, a cavity-ring 15 elastically fitted to the sectional pattern 3B and the cavity side half 5. Further, a one shot worth of synthetic resin is injected into the set cavity and in this case, the set cavity is made an enlarged cavity by moving the movable half 3 backward until the movable half 3 comes into contact with the movable platen 2 by a synthetic resin injection force. After that, the movable half 3 in contact with the movable platen 2 is advanced as it is to compress the cavity down to the size of the set cavity. Thus the method for injection- molding the optical disc base is as described.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a CD (compact disc), a DVD (digital versatile disc), and an MD.
The present invention relates to an injection molding die apparatus for manufacturing a disk base such as a (mini disk) and an injection molding method using the apparatus.

[0002]

2. Description of the Related Art Conventionally, disk single plates constituting optical disks such as CDs, DVDs and MDs are manufactured by injection molding. For example, a DVD single disk has a thickness of 0.
It is extremely thin, about 6 mm, and extremely precise molding is required to manufacture such a thin disk single plate. The injection molding is performed by synthesizing polycarbonate or the like in a cavity (a space in which synthetic resin is enclosed) formed by a fixed mold whose position is fixed and a movable mold which can come into contact with and separate from the fixed mold. It is to inject and harden resin.

Particularly, in the injection molding of the optical disc substrate, the injection resistance of the synthetic resin into the cavity is relaxed,
Moreover, in order to accurately transfer the information data of the stamper and to ensure a uniform density distribution of the synthetic resin, the synthetic resin was injected while retracting the movable mold with a slight resistance, and then became slightly larger than the set cavity. A so-called injection compression molding method is adopted in which the movable mold is compressed against the fixed mold until the cavity has the size of the original set cavity.

A hydraulic device is also used as a moving means for moving the movable mold with respect to the fixed mold in the injection compression molding. However, this hydraulic device is easily affected by the temperature of the hydraulic oil and pollutes the working environment. In addition, since hydraulic equipment uses a large amount of hydraulic oil, sufficient safety management is required, and if it exceeds a certain amount, it must be managed by a legal safety manager. It's troublesome. For this reason, the electric toggle mechanism is generally adopted.

[0005]

However, in the above-mentioned toggle mechanism, the movable die is brought into contact with the fixed die and pressure is generated immediately after which the lock state is established. Therefore, when the injection force of the synthetic resin, that is, the reaction force due to the injection filling force acts, the movable die cannot be naturally retracted.

The present invention has been made in view of the above technical background with the intention of solving the above problems.
In injection molding of a disk substrate in which a movable mold moves with respect to a fixed mold by a toggle mechanism, it is intended to allow a separation mold, which is a part of the movable mold, to be slightly retracted when a synthetic resin is injected. ..

[0007]

SUMMARY OF THE INVENTION The inventors of the present invention have, as a result of intensive studies to solve the above-mentioned problems, have provided a movable die with an elastic mechanism to solve the conventional problems. The inventors have found that they can be solved, and completed the present invention based on this finding.

That is, the present invention comprises (1) a mold clamping mechanism, a movable mold attached to the mold clamping mechanism via a movable platen, and a fixed mold forming a cavity together with the movable mold. The movable mold exists in a disk-based injection molding mold device provided with a separation mold that is elastically supported with a fixed gap with respect to a mold base fixed to a movable platen.

And (2), the mold clamping mechanism is present in the disk-based injection molding die device which is a toggle mechanism for clamping.

Further, (3) the present invention resides in a disk-based injection molding mold apparatus in which an elastic body is provided between the mold base and the separation mold.

Further, (4) the disk-based injection molding die device in which the elastic body is a coil-shaped spring.

Further, (5) the disk base injection molding die apparatus has a constant gap formed between the die base and the separation die of 25% to 35% of the size of the set cavity. .

Further, (6), the toggle mechanism exists in a disk-based injection molding die device driven by a servomotor.

Further, (7), the present invention resides in a disk-based injection molding die device in which a cavitation is elastically attached to a separation die of a movable die.

Further, (8), a separation mold which is elastically supported in a state in which there is a fixed gap with respect to a mold base fixed to the movable platen and attached via a toggle mechanism and the movable platen, A setting cavity is formed by a cavity ring that is elastically attached to a separation mold and a fixed mold, and one shot of synthetic resin is injected into the setting cavity, and it can be moved by the synthetic resin pouring input at that time. The mold is retracted until it abuts the movable platen to make the set cavity a larger augmented cavity, and then the movable die in contact with the movable platen is advanced as it is to compress the cavity to the size of the set cavity. A disk-based injection molding method characterized by the above.

Further, (9), the increasing cavity larger than the setting cavity is 25% of the setting cavity.
It lies in the disk-based injection molding method which is 35% in size.

Further, (10) a disk-based injection molding method in which the movable platen is moved with respect to a fixed mold by a toggle mechanism driven by a servomotor.

In accordance with the present invention, the present invention can naturally employ a mold apparatus having a structure in which two or more selected from the above 1 to 6 are combined.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a disk-based injection molding die apparatus and a disk-based injection molding method of the present invention will be described with reference to FIG.

This disk-based injection molding die device is
It comprises a toggle mechanism 1 for mold clamping, which is a mold clamping mechanism, a movable mold 3 supported by a movable platen 2, and a fixed mold 5 supported by a fixed platen 4, and the movable mold is , A separation mold 3 which is elastically supported with a constant gap with respect to the mold base 3A fixed to the movable platen.
It has B.

The toggle mechanism is a self-locking mechanism that passes a certain point (dead point) in the operation process.

The toggle mechanism 1 employed in the present invention has a ball screw 1b fixed to the output shaft of a servomotor 1a and a ball screw 1 at the center as shown in FIG.
Output rod 1c screwed to b, link 1d, one end of which is swingably connected to the end of output rod 1c, link 1
e, a link 1f and a link 1g swingably connected between the outer peripheral portion of the substrate 1h fixed to the servomotor 1a and the other end of the link 1d or the other end of the link 1e, and the back part of the movable platen 2. The outer periphery and the other end of the link 1d or the link 1e
The link 1i and the link 1j are swingably connected to the other end of the link.

In the toggle mechanism 1, when the servomotor 1a rotates in the normal direction and the ball screw 1b rotates in the normal direction, the output rod 1c screwed to the ball screw 1b advances toward the fixed mold 4. The forward movement of the output rod 1c causes the links 1d and 1e to stand up (output rod 1
The angle formed by the link 1f and the link 1i and the angle formed by the link 1g and the link 1j gradually increase, and finally become substantially linear with each other, that is, the movable mold 3 is described later. The state shown in FIG. 2B is obtained, which is in the mold closing position. In addition, by rotating the servo motor 1a in the reverse direction from this state, the movable mold 3
Immediately retreats.

A movable platen 2 is attached to each end of the link 1i and the link 1j constituting the toggle mechanism 1. An annular separation mold fixture 6 is fixed by screws 7 to the mold base 3A of the movable mold fixed to the movable platen 2. A shaft rod 9 is fixed to the centers of the movable platen 2 and the mold base 3A via a sleeve 8. A movable sleeve 10 having a three-step outer diameter, which has a larger diameter toward the movable platen side, is slidably fitted into the shaft rod 9.

The separation mold 3B, which is a part of the movable mold 3, is
In a state where the movable sleeve 10 is slidably accommodated in the internal space, the movable sleeve 10 is detachably attached to the die base portion 3A by the detachable die attaching tool 6. Separation mold 3B is mold base 3A
The configuration that can be attached in a state that is slidable with respect to and that does not slip out is as follows, for example.

That is, the collar portion 6a is provided inside the separation mold fixture 6.
Is integrally provided, and a separation mold 3B corresponding to the collar portion 6a.
A certain range of the outer circumference of is smaller than the other parts. Also,
The inner space of the separation mold 3B is formed with three different inner diameters corresponding to the three outer diameters of the movable sleeve 10. In addition, at the end of the small diameter portion of the movable sleeve 10, the fixed mold 5
Also, a sprue 11 for introducing a synthetic resin, which is formed to fill a space between a nozzle 19 for injection molding and a cavity, which will be described later, is formed (see FIG. 3B). Here, the sprue 11 is immediately separated from the disk substrate D.

Between the mold base 3A and the separation mold 3B,
A coil-shaped spring 12 which is an elastic body is provided, and the separation die 3B is elastically supported by the spring 12 with a constant gap L ₂ with respect to the die base 3A. In this case, the separation mold 3B has a collar portion 6a of the separation mold fixture 6.
Is stopped by means of which a constant gap L ₂ is defined. The constant gap L _{2 of} 1 is the gap L of the setting cavity S.
_It is preferably about 25% to 35% of ₀ .

That is, when the molded product is a disk substrate, the gap L ₂ is usually 1 mm or less, for example 0.2.
It is about mm. The elastic body may be replaced with, for example, an air cushion that uses fluid pressure instead of the spring.

The surface of the separating mold 3B is mirror-finished, and an annular groove is formed on the outer peripheral portion of the mirror surface. An annular cavity ring 15 is elastically attached to the spring holding hole 13 of the annular groove via a coiled spring 14. The cavity 15 defines a cavity 16 which is a space for injection and filling of synthetic resin together with the separation mold 3B and the fixed mold 5.

On the other hand, the fixed mold 5 is fixed to the fixed platen 4 with screws 17. A concave portion having a mirror-finished flat surface is formed on the surface of the fixed mold 5.
The stamper 18 to which information is applied is received and fixed by a stamper fixing mechanism (not shown). At the center of the fixed mold 5, a hole 5a is formed, which has a larger inner diameter on the outlet side and can receive the portion to be the sprue 11. Also,
A large hole (runner) 4a is also formed in the central portion of the fixed platen 4, and the nozzle 19 and the sprue 11 of the injection molding device are formed.
Can be connected in a communication state.

Next, with reference to FIGS. 2 and 3, an explanation will be given of a method of injection molding a disk base using the mold apparatus constructed as described above.

In FIG. 2A, the movable mold 3 is in a mold open position separated from the front of the fixed mold 5, and the nozzle 19 of the injection molding device is separated from the rear of the fixed mold 5. Wait,
FIG. 6 is a view showing a state where a stamper 18 is held by a fixed mold 5. In this state, when the ball screw 1b of the toggle mechanism 1 rotates forward, the movable platen 2 and the movable mold 3 advance toward the fixed mold 5, and finally, the movable mold 3 shown in FIG. The separation mold 3B, which is a part of the above, stops with the fixed mold 5 maintaining a predetermined gap L ₀ .

At this time, the cavity ring 15 is elastically pressed against the surface of the stamper 18 supported by the fixed mold 5 by the force of the spring 14. The space defined by the separation mold 3B, the fixed mold 5, and the cavity ring 15 that keeps the predetermined gap L ₀ is the setting cavity S. In this case, since the spring 12 is sufficiently strong, it is not compressed and the distance L ₂ is maintained. The spring force of the spring 12 is stronger than that of the spring 14. One shot of synthetic resin (for example, polycarbonate) is injected into the set cavity S. The state shown in FIG. 1 (A) above is the first half of the injection filling step in which a part of the synthetic resin is injected.

Further, the remaining synthetic resin is set in the set cavity S.
Once injected, the injection pressure of the synthetic resin causes the separation
The mold 3B abuts the mold base 3A against the force of the spring 12.
To the state shown in FIG. 2C (that is, L
₂Is zero). Separate mold 3B and fixed mold 5 at this time
Gap L between₁Is the above-mentioned predetermined gap L₀Greater
As a result, an augmented setting cavity is formed. here
Therefore, from the viewpoint of ensuring a uniform density distribution of the resin, L₁Is
L₀It is preferable to increase the size by 25% to 35%.
Yes. For example, if the molded product is a disk substrate as in the present invention,
If L₀Is 0.6 mm, L ₁Is about 0.8 mm.

After that, the ball screw 1b of the toggle mechanism 1 is slightly rotated in the forward direction so that the movable mold 3 in contact with the movable platen 2 has a cavity with a set cavity size as shown in FIG. 3 (A). Until, that is, movable mold 3
The resin is slightly advanced until the gap between the fixed mold 5 and the fixed mold 5 reaches a predetermined gap L _0, and the synthetic resin injected and filled in the cavity is compressed.

When the ball screw 1b of the toggle mechanism 1 is rotated in the reverse direction after the synthetic resin in the cavity is solidified, as shown in FIG.
The disk base D can be taken out by moving to a mold opening position separated from the front of the disk.

According to the disk-based injection molding method described above, when the synthetic resin is injected into the set cavity S, the separating mold 3B is retracted by the injection force (injection filling pressure) of the synthetic resin, and the cavity is set. Since the volume is larger than that of the cavity (interval between increased setting cavities; L ₀ + L ₂ ), the synthetic resin can be reasonably injected and filled into the cavity with a necessary and minimum filling resistance.

Then, due to the subsequent restoring movement of the separation mold 3B, a compressive force acts on the synthetic resin in the cavity, so that the synthetic resin is uniformly filled in the cavity. Therefore, in the molded disc substrate, residual stress in the substrate due to unnecessary filling resistance can be sufficiently reduced, and the pit shape of the stamper can be reliably transferred.

Although the present invention has been described above, the present invention is not limited to the embodiments, and other modifications can be made without departing from the essence thereof. Figure 1
The structure shown in FIG. 3 is a structural diagram for simply explaining the principle of the present invention. For example, the mounting structure of the separation mold mounting tool 6, the spring, etc. can naturally adopt other modes.

Further, the invention can be applied to an injection molding machine equipped with a hydraulic means for controlling the position of a die other than the toggle mechanism. Further, although the injection molding die apparatus and the injection molding method for injection molding the disk base are shown, the injection molding die apparatus and the injection molding method for members other than the disk base are also applicable. In that case, the distance between the movable platen and the separation mold is set according to the size of the molded product. Further, it is equally possible to adopt a mold in which the movable platen and the mold base are integrated (when the movable platen also serves as the mold base).

[0041]

As described above, according to the present invention, the movable metal mold is driven by the injection filling pressure of the synthetic resin injected into the cavity, although the movable metal mold adopts the toggle mechanism in which it is difficult to slightly retract. The mold, that is, the separation mold, can be slightly retracted, and the volume of the cavity can be increased. Therefore, the injection filling resistance of the synthetic resin into the cavity is alleviated, and the synthetic resin can be reasonably filled in the cavity. Further, by the subsequent restoring movement of the movable mold, the compressive force uniformly acts on the synthetic resin in the cavity, and a uniform density distribution of the synthetic resin can be secured.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a disk-based injection molding die device of the present invention.

FIG. 2 is a vertical cross-sectional view illustrating a molding process up to an injection filling process by the disk-based injection molding mold device of the present invention, (A) when the movable mold is in the mold opening position,
(B) shows the first half of the injection filling process, and (C) shows the second half of the injection filling process.

FIG. 3 is a vertical cross-sectional view for explaining a molding process after the compression process by the disk-based injection molding die device of the present invention,
(A) is for the compression process, and (B) is for the process of taking out the disk substrate with the movable mold at the mold open position.

[Explanation of symbols]

1 ... Toggle mechanism 1a ... Servo motor 1b ... Ball screw 1c ... Output rod 1d, 1e, 1f, 1g, 1i, 1j ... Link 1h ... substrate 2 ... Movable platen 3 ... Movable mold 3A ... Mold base 3B ... Separate mold 4: Fixed platen 5 ... Fixed mold 6 ... Separate mold attachment 7 ... screw 8 ... Sleeve 9 ... Axis rod 10 ... Movable sleeve 11 ... Sprue 12 ... Spring 13 ... Spring holding hole 14 ... Spring 15 ... Caviring 16 ... Cavity 17 ... screw 18 ... Stamper 19 ... Nozzle D ... Disk base S ... Setting cavity

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masao Hirosawa             11-5 Sakosanbancho, Tokushima City, Tokushima Prefecture Stock Association             Company Kitanouchi (72) Inventor Toshihiro Kayahara             1 Mitsubishi Materi, 3 Koganecho, Niigata City, Niigata Prefecture             Al Niigata Works F term (reference) 4F202 AH38 CA11 CB01 CB29 CK18                       CK25 CL42 CL49                 4F206 AH38 JA03 JL02 JN34 JN35                       JQ06 JQ81 JT05                 5D121 DD05 DD18

Claims (10)

[Claims] 1. A mold clamping mechanism, a movable mold attached to the mold clamping mechanism via a movable platen, and a fixed mold forming a cavity together with the movable mold, wherein the movable mold is movable. A mold apparatus for disk-based injection molding, comprising a separation mold which is elastically supported in a state having a certain gap with respect to a mold base fixed to a platen. 2. The mold device for disk-based injection molding according to claim 1, wherein the form clamping mechanism is a toggle mechanism for clamping. 3. The mold apparatus for disk-based injection molding according to claim 1, wherein an elastic body is provided between the mold base and the separation mold. 4. The mold device for disk-based injection molding according to claim 3, wherein the elastic body is a coil-shaped spring. 5. The disk-based injection molding according to claim 1, wherein the fixed gap formed between the mold base and the separation mold is 25% to 35% of the size of the set cavity. Mold equipment. 6. The disk-based injection molding die apparatus according to claim 2, wherein the toggle mechanism is driven by a servomotor. 7. The mold device for disk-based injection molding according to claim 1, wherein the cavitation is elastically attached to the separation mold of the movable mold. 8. A separation die, which is elastically supported with a certain gap with respect to a die base fixed to the movable platen and attached via a toggle mechanism and a movable platen, and an elastic pressure on the separation die. A cavity is formed by the cavitation and the fixed die that are attached to each other, and one shot of synthetic resin is injected into the setting cavity. It is characterized in that the set cavity is made to be a larger expanded cavity by abutting on the movable platen, and then the movable die in contact with the movable platen is advanced as it is to compress the cavity to the size of the set cavity. Disc-based injection molding method. 9. The disk-based injection molding method according to claim 8, wherein the expanded cavity larger than the set cavity has a size of 25% to 35% of the set cavity. 10. The disk-based injection molding method according to claim 9, wherein the movable platen is moved with respect to the fixed mold by a toggle mechanism driven by a servomotor.