JP2001062878A - Ultrasonic injection mold for optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the amplitude of ultrasonic waves transmitted in the radial direction of a cavity as small as possible. SOLUTION: In an ultrasonic injection mold for an optical disk having a movable side mold 4, a fixed side mold 3, the disk molding cavity 6 formed between the contact surfaces 3a, 4a of the movable and fixed side molds 4, 3, the stamper 15 arranged to the bottom part of the cacity 6 to form a pit to the surface of a disk and the ultrasonic generating means 7 attached to the mold side mold 4 or the fixed side mold generating means 7 attached to the movable side mold 4 or the fixed side mold 3 in order to apply ultrasonic waves to the cavity 6 at a time of injection molding, one or a plurality of slits 20 are formed on the circumference of a circle within the region L where in the direction crossing the diameter direction of the cavity 6. The slits 20 are pref. formed at places of nλ/4 (n=1, 3, 5 ...) from an ultrasonic input part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic injection molding die for an optical disk, and more particularly, to an ultrasonic injection molding die for an optical disk which has excellent transferability and can effectively prevent the occurrence of birefringence and warpage. .

[0002]

2. Description of the Related Art An optical disk such as a CD or a DVD includes a movable mold, a fixed mold, and a circular cavity for molding a disc formed on an abutting surface of the movable mold and the fixed mold. A resin, such as molten polycarbonate, is injected into a mold having a stamper for forming irregularities (pits) on the surface of the disk, which is disposed at the bottom of the cavity, and molded.

[0003] When a thin product is obtained by injection molding as in the above-mentioned optical disc, the flowability of the molten resin in the cavity is improved to prevent the occurrence of uneven filling, and defects such as shrinkage deformation and birefringence are caused. Must be prevented. In order to prevent the occurrence of such defects, for example, Japanese Patent Application Laid-Open
No. 661, the relationship between the equivalent diameter (D) of the mold and the wavelength (λ) of the ultrasonic vibration is D <0.
Injection molding is performed so as to be 6λ.

However, in the conventional ultrasonic molding method described above, since only the longitudinal vibration is used, the diameter of the surface (the contact surface between the fixed mold and the movable mold) on which the cavity of the optical disk molding mold is formed (the diameter of the cavity). When the length of the ultrasonic wave (usually about 210 mm) is set to １ ／ or more of the resonance wavelength (λ) of the ultrasonic wave (for example, 130 mm or more at a frequency of 19 KHz in a SUS mold), vibration transmitted in the radial direction occurs. Therefore, the fixed portion of the mold and the mounting portion of the nozzle cannot be matched with the "node" of vibration (the point where the amplitude becomes 0), and there is a problem that it is difficult to hold the mold and the nozzle.

In the conventional ultrasonic molding die structure,
Since only longitudinal vibration is used, the thickness of at least one wavelength is necessary for the movable mold and the fixed mold as a whole, and the total thickness is 400 mm or more when the vibration direction converter is included. For this reason, there is also a problem that it cannot be mounted between the die plates of the production machine (30-ton injection molding machine).

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is directed to an ultrasonic injection molding die for an optical disk for injection molding an optical disk. Ultrasonic injection for optical discs that can maintain good transferability by keeping the amplitude as small as possible, and can hold molds and nozzles between die plates well while preventing birefringence and shrinkage deformation. An object is to provide a molding die.

[0007]

In order to solve the above problems, an ultrasonic injection molding die for an optical disk according to the present invention comprises a movable die, a fixed die, and a contact between the movable die and the fixed die. A cavity for forming a disk formed on the surface, a stamper disposed at the bottom of the cavity for forming pits on the surface of the disk, and the movable metal for applying ultrasonic waves to the cavity during injection molding. An ultrasonic injection molding die for an optical disk having a mold or ultrasonic generating means attached to the fixed die, wherein the cavity is formed in a region where the cavity of the movable die and the fixed die is formed. And one or a plurality of slits are formed in a direction intersecting the radial direction. By forming the slit, the thickness of the portion is reduced, so that vibration is suppressed at that portion. Therefore, the amplitude of the vibration transmitted in the radial direction of the cavity can be reduced.

[0008] The slit is used to change the wavelength of the ultrasonic wave whose transmission direction has been changed inside the movable mold or the fixed mold to λ.
When the ultrasonic wave is input to the movable mold or the fixed mold from the ultrasonic input unit, nλ / 4 (n = 1,
3,5 ...). Here, the “ultrasonic input unit” refers to a portion where the ultrasonic generating means or the vibration direction converter comes into contact with the movable mold or the fixed mold. At nλ / 4 (n = 1, 3, 5...), the amplitude of the vibration resonance becomes a node. By forming a slit at this position, the amplitude of vibration transmitted in the radial direction can be minimized.

Particularly, in a large-diameter mold, a plurality of rows are preferably formed inward from the outer peripheral edge of the cavity along the radial direction of the cavity. Also in this case, the amplitude of the vibration transmitted in the radial direction can be further reduced by providing at the position where the amplitude of the resonance becomes a node, that is, at nλ / 4 (n = 1, 3, 5,...). .

It is preferable that the ultrasonic wave generating means is provided at an input end of a vibration direction converter having an output end connected to the ultrasonic input section of the movable mold or the fixed mold. Vibration direction converters are LL type, LLL type, RL type
It can be any of shapes. By using the vibration direction converter, the input vibration can be amplified and output to the mold, and the longitudinal vibration having a larger amplitude can be given to the cavity to improve the fluidity.

Further, the movable mold and the vibrating direction converter or the fixed mold may be provided with product release means for releasing the injection molded product from the cavity. As a releasing means, a protruding pin that protrudes into the cavity when the mold is opened is generally used. By using such a product releasing means, it is possible to reliably release the molded product from the mold.

[0012] In particular, if the release means is configured to release the product from the cavity by vibrating the movable mold or the fixed mold having the stamper, a taper is formed on the irregularities of the stamper. This makes it possible to form the irregularities at a high density, thereby forming a disk capable of recording a large amount of information.

It is preferable that the movable mold and the fixed mold are guided by a spigot type guide means at the time of closing or opening the mold. As a guide for the mold when opening and closing the mold, a guide post provided on one side of the mold
A guide post method in which a guide pin provided in the other side of the mold is inserted, and an inlay method in which a conical pin provided in the other side of the mold is fitted into a conical hole provided in one side of the mold. However, the present inventor conducted a comparative experiment between the guide post method and the spigot method, and as a result, it was found that the spigot method had a greater effect of suppressing the vibration of the nozzle joint on the fixed mold side.

The ultrasonic wave generating means generates transverse vibration or radial vibration transmitted in the radial direction of the cavity, in addition to longitudinal vibration, in the entire fixed mold and movable mold. Is preferred. In addition to longitudinal vibration, transverse vibration or vibration transmitted in the radial direction of the cavity is added to make the vibration complex, so that the thickness of the movable mold and the fixed mold is smaller than when only longitudinal vibration is used. Less than half. Further, the movable mold and the vibrating direction converter or the fixed mold may be provided with a punch means for punching (punching) a predetermined portion of an injection-molded product. A protruding product releasing means may be configured.

A supporting member is inserted into the slit,
It is preferable that one end of the support member supports the bottom of the slit during injection molding. In this case, the width t of the gap between the support member and the inner wall of the slit is 0.1
It is preferable to set the range of mm <t <0.3 mm. The other end of the support member may be attached to a fixed mold fixing member for fixing the fixed mold or a movable mold fixing member for fixing the movable mold. An attachment member may be provided near the mold, and the support member may be attached to the attachment member.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an ultrasonic injection mold for an optical disk according to the present invention will be described below in detail with reference to the drawings. It should be noted that the present invention is not limited at all by the following embodiments, and can be variously modified within the scope of the present invention.

[First Embodiment] FIG. 1 shows a first embodiment of the present invention.
FIG. 2 is a side view showing a cross section of a part of the ultrasonic injection molding die for an optical disk according to the embodiment, and FIG. 2 is a diagram illustrating a displacement waveform of vibration transmitted through the die in FIG.

[Injection Molding Machine] In an injection molding machine to which the ultrasonic injection molding die for an optical disk of the present invention is applied, a molten resin is pressed into a mold, and the resin is formed into a shape corresponding to a cavity shape. And all ultrasonic injection molding machines for optical disks that are molded and removed from the mold. In the injection molding machine of this embodiment, the fixed mold 3 and the movable mold 4 described in detail below are first clamped under no load, and then the molten resin is injected from the nozzle 1 into the cavity 6 at high pressure. Then, the fixed mold 3 and the movable mold 4 are slightly opened. Thereafter, compression molding is performed while applying a mold clamping pressure to the movable mold 4, and a molded product is taken out after cooling. The ultrasonic wave is applied during the period from the start of the injection of the resin to the cooling, and at the time of release after the mold is opened.

[Mold] As shown in FIG. 1, the ultrasonic injection molding mold for an optical disk according to this embodiment has a fixed mold 3 having a sprue 5 on a center axis X, and a fixed mold 3 opposed to the fixed mold 3. And a movable mold 4 arranged in the same manner.

The fixed die 3 is fixed to the fixed die fixing plate 2 by the fixed die holding member 13, and the movable die 4 is fixed to the movable die fixing plate 9 by the movable die holding member 10.
Further, the movable mold fixing plate 9 is attached to the tip of the piston rod of the hydraulic cylinder 11, and moves the movable mold 4 forward and backward with respect to the fixed mold 3 as the piston rod moves forward and backward. The mold clamping and mold opening of the movable mold 4 are performed.

A circular cavity 6 for molding an optical disk is formed on the contact surfaces 3a and 4a where the fixed mold 3 and the movable mold 4 contact each other. A stamper 15 for forming irregularities (pits) on the surface of the optical disk is disposed at the bottom of the cavity 6 on the movable mold 4 side. A cooling water passage 16 is formed around the cavity 6 inside the fixed mold 3 and the movable mold 4.

[Form of Outer Peripheral Edge of Mold] The outer peripheral edges of the fixed mold 3 and the movable mold 4 have stepped portions 3b each having a reduced thickness in a thickness direction (a direction parallel to the X-axis). , 4b are formed. Here, the relationship between the cross-sectional area of the stepped portions 3b and 4b and the cross-sectional area of the portion where the stepped portions 3b and 4b are not formed is preferably as follows. That is, the stepped portion 3
b, 4b, and II-II, II'-II 'passing through portions where the stepped portions 3b, 4b are not formed, with respect to the cross-sectional area of the portion cut along the II, I'-I' lines passing through It is preferable that the cross-sectional area of the portion cross-sectional along the line is formed in the range of 0.85 to 0.95 times.

Flanges 3c and 4c are further formed on the outer peripheral side of the stepped portions 3b and 4b. Flanges 3c, 4
c is a fixed mold fixing plate 2 and a movable mold fixing plate 9 respectively.
Is a fixing part for fixing the fixed mold 3 and the movable mold 4 to the fixed mold 3. In the stepped portions 3b and 4b, the amplitude of the vibration transmitted in the radial direction of the cavity 6 becomes a node. Therefore, it is preferable that the thickness of the flange portions 3c and 4c provided on the outer peripheral side is made as thin as possible. In consideration of the pressure applied to the flange portions 3c and 4c during mold clamping, 5 mm to 1 mm
It is preferably 0 mm. In addition, the flange portions 3c, 4
In order to reduce the pressure shared by c as much as possible,
It is preferable that the movable mold holding member 10 and the fixed mold holding member 13 contact not only the flange portions 3c and 4c but also the stepped portions 3b and 4b.

[Slit] A slit 20 is formed in the fixed mold 3 and the movable mold 4 from the surface facing the fixed mold fixed plate 2 and the movable mold fixed plate 9 toward the cavity 6. The slit 20 is formed on the circumference in the radial region L (see FIG. 2) of the fixed mold 3 and the movable mold 4 in which the cavity 6 is formed. The slit 20 is provided in the cavity 6
The part where the vibration wave transmitted in the radial direction of the node becomes a node, that is,
From the center of the cavity 6 on the X-axis passing through the part (ultrasonic input part) where the vibration direction converter 8 and the movable mold 4 come into contact with each other,
Nλ / 4 (n = 1, 3, 5,...) In the radial direction of the cavity 6
However, it is preferable to form it at a position closest to the outer peripheral edge of the cavity 6. If the slit 20 is formed at this position, the maximum vibration suppressing effect can be obtained.

The radial width W of the cavity 6 of the slit 20
Is preferably not more than 10 mm, and is preferably not more than 0.1 mm so that the opposing opening edges of the slit 20 do not come into contact when the dies 3 and 4 are vibrated. Further, the depth of the slit 20 is preferably about half the thickness of the molds 3 and 4.

The shape of the slit 20 and how to arrange it in the fixed mold 3 and the movable mold 4 are arbitrary. FIG. 3 is a plan view of a mold showing the shape and arrangement of the slit 20. In the example shown in FIG. 3A, a single slit 20 is formed in an annular shape concentric with the cavity 6. FIG.
In the example shown in (b), a plurality of slits 20 formed by equally dividing the circumference are arranged along the concentric circle of the cavity 6. In the example shown in FIG.
Are arranged in two rows along concentric circles having different diameters of a radius nλ / 4 (n = 1, 3, 5,...). FIG. 3 (c)
In the case of the example shown in FIG.
Is preferably formed along a concentric circle of the cavity 6 having a radius of nλ / 4 (n = 1, 3, 5...).

It is preferable that the cross-sectional shape of the slit 20 is appropriately selected according to the amplitude of vibration and the metal forming the dies 3 and 4. As shown in FIG. 4 (a), the cross-sectional shape of the slit 20 may be formed in an upward U-shape, but FIG.
It is preferably formed in a U-shape as shown in FIG. Further, as shown in FIG. 4C, the wall surface facing the slit 20 may be inclined.

The nozzle 1 for supplying the molten resin to the cavity 6 is connected to the inlet of the sprue 5 of the fixed mold 3. Examples of the resin injected from the nozzle 1 include optical amorphous thermoplastic resins such as polycarbonate, polymethyl methacrylate, and amorphous polyolefin used for manufacturing optical disks.

[Guide System for Opening / Closing Mold] When performing injection molding, it is necessary to accurately position the fixed mold 3 and the movable mold 4 relative to each other. In order to accurately move the movable mold 4 with respect to the fixed mold 3 during mold clamping, the fixed mold 3
Alternatively, a guide post (or guide hole) provided on one of the movable molds 4 and a guide pin provided on the other of the fixed mold 3 or the movable mold 4 and inserted through the guide post. And a conical hole provided in the other of the fixed mold 3 or the movable mold 4 in a conical hole provided in one of the fixed mold 3 and the movable mold 4. There is a spigot type in which the pin is fitted.

As will be described later, the present inventor conducted an experiment to determine which of the guide post method and the spigot method has the greater vibration suppression effect. As a result, it was found that the guide method of the spigot type was more excellent in the vibration suppressing effect at the nozzle connection portion on the fixed mold side. Therefore,
In the mold of this embodiment, the contact surface 4a of the movable mold 4
A convex portion 17 having a trapezoidal cross section is formed continuously along the circumference surrounding the cavity 6, and a concave portion 18 having a trapezoidal cross section into which the convex portion 17 is fitted is formed on the contact surface 3 a of the fixed mold 3.

The maximum width of the tip of the convex portion 17 (the portion where the convex portion 17 protrudes from the contact surface 4a) can be about 10 mm, but the amplitude of the vibration of the portion where the nozzle 1 contacts the fixed mold 3 is set. Is preferably made as small as possible, and preferably about 4 to 5 mm. Note that the convex portion 17 can be provided at any position as long as it is outside the cavity 6. In addition, fixed mold 3
Alternatively, a protrusion may be provided on one of the movable molds 4 and a recess may be provided on the other.

[Vibration direction converter and vibrator] Movable mold 4
The vibration direction converter 8 is mounted on the central axis X on the surface facing the hydraulic cylinder 11. Vibration direction converter 8
Can orthogonally transform the vibration input from the vibration input surface and output it from the vibration output surface. A vibrator 7 as a vibration source is attached to an end face of one of the two vibrating bodies 8a and 8b constituting the vibrating direction converting body 8 which is orthogonal to the central axis X.
The end face of the vibrating body 8 b parallel to the movable mold 4 is in contact with the movable mold 4.
In the vibration direction converter 8, it is preferable that the output side vibration body 8b is formed to be slightly longer than the input side vibration body 8a. By doing so, it becomes possible to amplify the input vibration from the vibrating body 8a and output it from the end face of the vibrating body 8b.

The vibration direction converter 8 may be any of a multi-dimensional vibration direction converter such as an LL converter, an LLL converter, or an RL converter. The output of the vibrator 7 is 1.
It is preferable to use the one having about 2 Kw, but when the molds 3 and 4 become large, a plurality of, for example, three vibrators 7 are attached to this vibration input end by using an RL converter, The total output of the vibrator 7 can be tripled.

The vibration output from the vibrator 7 preferably generates not only longitudinal vibration but also horizontal vibration or radial vibration transmitted in the radial direction of the cavity in the whole mold. By using these combined vibrations, the thickness of the mold can be reduced. The frequency generated by the vibrator 7 may be about 1 KHz to 1 MHz, but it is preferable to output ultrasonic waves of about 10 KHz to 100 KHz in consideration of noise and the output of the vibrator. The amplitude of the ultrasonic wave output from the vibrator 7 is determined according to the fatigue strength of the metal forming the fixed mold 3 or the movable mold 4 with respect to the ultrasonic vibration. For example, the maximum amplitude when using a stainless steel material is about 20 μm, the maximum amplitude for duralumin is about 40 μm, and the maximum amplitude for titanium alloy is about 1 μm.
00 μm.

The vibration generated by the vibrator 7 is converted in the orthogonal direction by the vibration direction converter 8 as shown in FIG. In this case, the vibration direction converter 8 and the stationary mold 3 are positioned so that the antinode of vibration resonance is located at the joint between the vibration direction converter 8 and the stationary mold 3. Further, the cavity 6 is located at the antinode of vibration resonance. By doing so, the cavity 6 can be vibrated at the maximum amplitude,
The flow of the molten resin can be optimized.

[Product Release Means] In the case of injection molding of a thin molded article having fine irregularities (pits) on the surface, such as an optical disk, the molded article may have a pit deviation from the cavity 6 when the mold is opened. It is preferable to provide a product release means so that the release can be surely performed without causing the release. In this embodiment, a protruding pin 12 as a product release means is fixed to a movable mold fixing plate 9, and the tip thereof is inserted through the vibration direction converter 8 and the movable mold 4 along the central axis X to form a cavity 6.
Extending to The protruding pin 12 is provided in the cavity 6.
The cylinder (not shown) can be moved forward and backward to eject and remove the molded product formed therein. Also,
The protruding pin 12 is protruded through the molded product by a punch mechanism 25 using the cylinder as a driving body when performing drilling on the molded product molded in the cavity 6.

As the product releasing means, the above-mentioned projecting pin 1 which comes and goes in the cavity 6 when the mold is opened is used.
Although 2 is common, other means such as a robot hand for directly taking out a molded product may be used. Further, the movable mold 4 may be vibrated, or a combination of the vibration of the movable mold 4 and air blow may be used. The use of the release means by vibration eliminates the necessity of forming a punch taper in the irregularities of the stamper 15 and enables the irregularities to be formed at a high density, thereby forming a disk capable of recording a large amount of information. Becomes possible.

[0038]

Next, the result of an experiment performed using the ultrasonic injection molding die for an optical disk according to the first embodiment of the present invention will be described in comparison with a comparative example. (1) The guide method for opening and closing the mold with the fixed mold 3 and the movable mold 4 shown in FIG.
The amplitude of each part was measured for Example 1 in which an ultrasonic wave of 9.5 KHz was output. As a result, the amplitude of the fixed part of the movable mold (vertical / horizontal direction) 0.79 μm / 0.35 μm The amplitude of the fixed part of the fixed mold (vertical / horizontal) 0.25 μm / 0.11 μm Nozzle connection part Was 0.42 μm.

(2) As Comparative Example 1, a fixed mold and a movable mold having the same shape as those in (1) having no slit were used, the guide method was an in-row method, and a frequency of 19.5 KHz from the vibrator was used. Sound waves were output. As a result of measuring the amplitude of the same part as in (1), the amplitude of the fixed part of the movable mold (vertical / horizontal) 1.0 μm / 10 μm The amplitude of the fixed part of the fixed mold (vertical / horizontal) 0. The amplitude of the 35 μm / 3.5 μm nozzle connection was 9.0 μm. It can be seen that the horizontal amplitude of the fixed portion and the amplitude of the nozzle connection portion are large, and the vibration loss from the mold is extremely large. The vibrator 7 was overloaded and stopped oscillating.

(3) As Comparative Example 2, the same mold as in (1) was used, and a guide system was used as a guide post system, and ultrasonic waves having a frequency of 19.5 KHz were output from a vibrator.
As a result of measuring the amplitude of the same part as (1), the amplitude of the fixed part of the movable mold (vertical direction) 1.9 μm The amplitude of the fixed part of the fixed mold (vertical direction) 1.7 μm The amplitude of the nozzle connection part 3. 4 μm. The amplitude of the nozzle connection part is increased about eight times as compared with (1), and if molding is performed as it is, there is a possibility that air may be drawn in from the nozzle 1 to cause molding failure.

As is clear from the above results, the fixed mold 3
And a slit 20 is formed in the movable mold 4 and the cavity 6 is formed by adopting an inlay system as a guide system.
The amplitude of the vibration transmitted in the radial direction can be reduced, and a good molded product can be obtained.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a side view showing a cross section of a part of the ultrasonic injection molding die for an optical disk according to the second embodiment of the present invention, and FIG. 6 is provided with a slit of the ultrasonic injection molding die for an optical disk of FIG. FIG. In the second embodiment, the portions where the slits 20 of the fixed mold 3 and the movable mold 4 are provided are
It is supported by the support member 30.

That is, when the slit 20 is formed on the back side of the area where the cavity 6 is formed as in the fixed mold 3 and the movable mold 4 of the present invention, the amplitude of the radial vibration can be effectively reduced. Although it is possible, since the thickness of the portion is reduced, the fixed mold 3 and the movable mold 4 are easily bent by the internal pressure of the cavity 6 during injection molding. Since the bending of the molds 3 and 4 causes variation in the thickness of the molded product, in this embodiment, the supporting member 3 is used.
That is, the portion where the slit 20 is formed is supported from behind by the 0, so that the bending of the molds 3 and 4 is reduced.

The support member 30 has one end fixed to the fixed mold fixing plate 2.
And the other end is fixed to the movable mold fixing plate 9 by a bolt, welding, or the like, and the other end is fixed to the slit 2 of the fixed mold 3 and the movable mold 4.
0 is in contact with the bottom 20b. Inner wall 2 of slit 20
As shown in FIG. 6, a slight gap is formed between the support member 30 and the support member 30 so that the inner wall 20a does not contact the support member 30. The width t of the gap is such that the inner wall 20a of the slit 20 when the molds 3 and 4 are vibrated.
To the extent that the support member 30 does not come into contact with
It is preferably larger than mm. When vibration is applied to the molds 3 and 4, the inner wall 20a of the slit 20 and the support member 3
In order to keep the rigidity of the support member 30 as high as possible within a range in which 0 does not make contact, the width t is less than 0.5 mm,
In particular, it is preferable that the thickness be less than 0.3 mm.

Further, the material of the support member 30 has a Young's modulus large enough to suppress the bending of the portion where the slit 20 is formed against the pressure in the cavity 6, and has a fixed metal. It is preferable that the mold 3 and the movable mold 4 have the same coefficient of thermal expansion as the thermal expansion coefficient (for example, the same material as the fixed mold 3 and the movable mold 4). If the coefficient of thermal expansion of the support member 30 is too small compared to the fixed mold 3 and the movable mold 4, the other end of the support member 30 separates from the bottom of the slit 20 during injection molding, and the portion where the slit 20 is formed is sufficiently removed. You can't support it. If the coefficient of thermal expansion is too large compared to the fixed mold 3 and the movable mold 4, the support member 30 pushes the bottom 20b of the slit 20 with an excessive force during injection molding. To increase the deflection.

FIG. 7 is a plan view showing the arrangement of the support members 30. FIG. As shown in FIG.
May be provided over the entire slit 20, but if bending can be effectively suppressed at the portion where the slit 20 is formed, a predetermined interval is provided between the slits 20 as shown in FIG. Preferably, a plurality (for example, four) may be provided at equal intervals.

[0047]

EXAMPLES Hereinafter, the results of experiments performed using the ultrasonic injection molding die for an optical disk according to the second embodiment of the present invention will be described in comparison with comparative examples. (1) The support member 30 shown in FIG. 5 is provided, and the guide method for opening and closing the molds of the fixed mold 3 and the movable mold 4 is the in-row method.
The maximum value and the minimum value of the amount of deflection were measured for Example 2 in which ultrasonic waves of Hz were output. As a result, the internal pressure of the mold was 5.5 MPa. The flexure of the mold was 7 μm at the maximum and 1 μ at the minimum. (2) The same guide method as that of the second embodiment is used, and a case where a supporting member is provided and no ultrasonic wave is output
The maximum and minimum values of the amount of deflection were measured. The results are shown below. Comparative Example 3 (with support member, no ultrasonic output): Mold inner pressure 8.7 MPa Deflection amount of mold Maximum 14 μm Minimum 2 μ (3) The same guide method as in Example 2, except that no support member is provided. The same case as in Example 1 was set as Comparative Example 4, and the maximum value and the minimum value of the deflection amount were measured. The results are shown below. Comparative Example 2 (No support member, no ultrasonic output): Mold internal pressure 8.7 MPa Deflection amount of mold Maximum 22 μm Minimum 12 μ As can be seen from the comparison result of more than, support member 30 was provided, and ultrasonic waves were further applied. By applying the voltage, the amount of bending of the molds 3 and 4 could be significantly reduced.

[Third Embodiment] A third embodiment of the present invention will be described with reference to FIG. FIG. 8 is a side sectional view of a part of an ultrasonic injection molding die for an optical disk according to a second embodiment of the present invention. In this embodiment,
An attachment plate 35 for the support member 30 is provided near the movable mold 4 so as to face the movable mold 4. The mounting plate 35 is firmly fixed to the movable mold holding member 10 by bolts, welding, or the like. The other end of the support member 30 is fixed to the mounting plate 35. Then, as in the second embodiment, one end of the support member 20 is inserted into the slit 20 and the slit 2
0 abuts on the bottom 20b.

By providing the mounting plate 35 near the movable mold 4, the length of the support member 30 on the movable mold 4 side can be made shorter than that of the support member 30 of the second embodiment. Therefore, the compression strain in the axial direction of the support member 30 at the time of injection molding can be reduced, and the bending of the portion where the slit 20 is formed can be further reduced.

[0050]

According to the present invention, the amplitude of the vibration transmitted in the radial direction of the cavity is effectively reduced, the flow of the molten resin is kept good, the transferability is kept good, and the birefringence and shrinkage deformation are suppressed. Generation can be prevented, and vibration loss from the mold can be prevented as much as possible, so that the mold and the nozzle can be favorably held. In addition, the bottom of the slit formed in the mold is supported by a support member, and since the pressure inside the mold is reduced by applying ultrasonic waves, the increase in bending of the mold due to the decrease in wall thickness is suppressed, An optical disk with small thickness variations can be obtained.

[Brief description of the drawings]

FIG. 1 is a partially sectional side view schematically showing an ultrasonic injection molding die for an optical disk according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a displacement waveform of vibration transmitted through the mold of FIG. 1;

FIG. 3 is a plan view of a mold showing an arrangement of slits.

FIG. 4 is a diagram showing a cross-sectional shape of a slit.

FIG. 5 is a side view showing a cross section of a part of an ultrasonic injection molding die for an optical disk according to a second embodiment of the present invention.

6 is an enlarged view of a portion provided with a slit of the ultrasonic injection molding die for an optical disk of FIG. 5;

FIG. 7 is a plan view showing an arrangement of support members.

FIG. 8 is a side sectional view of a part of an ultrasonic injection molding die for an optical disk according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle 2 Fixed mold fixing plate 3 Fixed mold 4 Movable mold 5 Sprue 6 Cavity 7 Vibrator 8 Vibration direction converter 9 Movable mold fixing plate 10 Movable mold holding member 11 Hydraulic cylinder 12 Projecting pin (product release) Means) 15 stamper 17 convex portion 20 slit 20a inner wall of slit 30 support member 35 mounting plate (mounting member)

Continued on the front page (72) Inventor Tetsuya Iida 6-1-1 Fujimi, Tsurugashima-shi, Saitama Pioneer Corporation (72) Inventor Noriyoshi Shida 6-1-1 Fujimi, Tsurugashima-shi, Saitama Pioneer Corporation Within the Research Institute (72) Keiji Suga Innovator, 6-1-1-1 Fujimi, Tsurugashima-shi, Saitama Prefecture (72) Inventor Kenichi Ishiguro 2680 Nishihanawa, Tatomicho, Nakakoma County, Yamanashi Prefecture Pioneer Video Corporation (72) Inventor Yasunobu Higashiya 2680 Pioneer Video Co., Ltd., 2680 Nishi-Hanawa, Tatomi-cho, Nakakoma-gun, Yamanashi Prefecture Coast No. 1 1F term (reference) 4F202 AH79 CA11 CB01 CK06 CM02

Claims (13)

[Claims] 1. A movable mold and a fixed mold, a disc molding cavity formed on an abutting surface of the movable mold and the fixed mold, and a pit disposed on the bottom of the cavity and formed on a surface of the disc. An ultrasonic injection molding die for an optical disc, comprising: a stamper for forming a mold; and ultrasonic generating means attached to the movable die or the fixed die for applying ultrasonic waves to the cavity during injection molding. A mold, wherein one or more slits are formed in a direction intersecting a radial direction of the cavity on a back side of a region where the cavity of the movable mold and the fixed mold is formed. Ultrasonic injection molding die for optical disks. 2. When the wavelength of the ultrasonic wave transmitted in the radial direction of the cavity is λ, the ultrasonic wave is input to the movable mold or the fixed mold from an ultrasonic input unit for nλ / 4 ( The slit is formed at a position where n = 1, 3, 5,...
Ultrasonic injection molding die for an optical disk according to item 1. 3. The ultrasonic injection molding die for an optical disk according to claim 1, wherein a plurality of said slits are formed inward from an outer peripheral edge of said cavity. 4. The ultrasonic generator according to claim 1, wherein said ultrasonic generator is provided at an input end of a vibration direction converter having an output connected to said ultrasonic input section of said movable mold or said fixed mold. Item 7. An ultrasonic injection molding die for an optical disk according to any one of Items 1 to 3. 5. A product releasing means for releasing an injection-molded product from the cavity to either the vibration direction converter or the fixed mold to which the movable mold and the ultrasonic wave generating means are attached. The ultrasonic injection molding die for an optical disk according to any one of claims 1 to 4, further comprising: 6. The product release means according to claim 5, wherein the product release means is configured to release the product from the cavity by vibrating the movable mold or the fixed mold having the stamper. The ultrasonic injection molding die for an optical disc according to the above. 7. The vibration direction converter or the fixed mold to which the movable mold and the ultrasonic wave generating means are attached,
7. An ultrasonic injection molding die for an optical disk according to claim 1, further comprising a punch means for punching a predetermined portion of the injection molded product. 8. The optical disk according to claim 1, wherein the movable mold and the fixed mold are guided by a spigot-shaped guide means when the mold is closed or the mold is opened. Ultrasonic injection molding die. 9. The ultrasonic generator generates a transverse vibration or a radial vibration transmitted in a radial direction of the cavity, in addition to a longitudinal vibration, in the whole of the fixed mold and the movable mold. An ultrasonic injection molding die for an optical disk according to any one of claims 1 to 8. 10. A super optical disk according to claim 1, wherein a support member is inserted into said slit, and one end of said support member supports a bottom portion of said slit during injection molding. Sonic injection mold. 11. The optical disk according to claim 10, wherein a width t of a gap between the support member and an inner wall of the slit is in a range of 0.1 mm <t <0.3 mm. Ultrasonic injection mold. 12. The other end of the support member is attached to a fixed mold fixing member for fixing the fixed mold or a movable mold fixing member for fixing the movable mold. 12. The ultrasonic injection mold for an optical disk according to 10 or 11. 13. The ultrasonic injection for an optical disk according to claim 10, wherein an attachment member is provided near the fixed mold or the movable mold, and the support member is attached to the attachment member. Molding mold.