JPH08156035A - Disk substrate molding tool - Google Patents

Abstract

PURPOSE: To prevent defective molding of a disk substrate such as burr, dragging, etc., by a method wherein an interval of vents in actual molding is made adjustable. CONSTITUTION: Vents 6, 7 are formed between an outer periphery presser ring 5 and a surface of a stamper, and between the presser ring 5 and a tapered outer periphery 11a of a mirror surface 11 of a fixed side mirror block 12. A groove 40 is formed on a surface opposed to a stamper of the outer periphery presser ring 5, a micro-sheathed heater 41 is fitted to the groove 40, and a power source is connected to its connector part 42 via a converter. In order to thermally expand the outer periphery presser ring 5 according to thermal expansion of the fixed side mirror block 12, a power source having a specified voltage is supplied to the micro-sheathed heater 41 to heat the outer periphery presser ring 5 at a specified temperature, and the vents 6 are formed at specified intervals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for molding a disk substrate, and more particularly to a mold for molding a disk substrate in which a vent is formed between the mold and the outer peripheral pressing ring of the stamper. .

[0002]

2. Description of the Related Art Compact discs, video discs,
Discs such as magneto-optical discs as information recording media have their respective sizes according to their types, and a mold corresponding to the standard of each disc substrate is used to mold a disc substrate of a desired type. .

As shown in FIG. 1, a disk substrate molding die includes a fixed die 1 having a mirror surface 11 formed thereon, and the fixed die.
Mirror surface of fixed mold 1
1 and a movable mold 2 having a mirror surface 21 facing it,
The cavity 3 is formed by clamping both molds 1 and 2. In the center of the fixed mold 1, sprue bush
14 is provided, and the stamper 4 is held on the mirror surface 11, 21 of either the fixed mold 1 or the movable mold 2. In general, the stamper 4 has its inner peripheral edge held by the flange portion of the stamper holder 32, and its outer peripheral edge held by the outer peripheral pressing ring 5.

The fixed mold 1 and the movable mold 2 are formed by attaching mirror blocks 12 and 22 having mirror surfaces 11 and 21 to plates 10 and 20, respectively, and are provided with a temperature adjusting mechanism. This temperature adjustment mechanism is a mirror block
The temperature adjustment grooves 16 and 27 are formed on the surface opposite to the mirror surfaces 11 and 21 of 12,22, and the cover plates 17 and 28 are attached so as to seal the temperature adjustment grooves 16 and 27 in a watertight manner to form a flow path. It supplies and circulates a temperature control medium such as water or oil having a predetermined temperature to the flow path. For example, when molding a compact disc having a diameter of 120 mm, the temperature of the mirror surface is generally adjusted to 80 to 90 ° C. There is.

[0005] A sprue bush is formed by heating and melting the molding material.
As shown in FIG. 4, the mirror block 12 and the outer peripheral pressing ring are used to release the air in the cavity 3 and to release the gas generated from the molding material from the cavity 3 when the cavity 3 is injected and filled through the cavity 14. A vent 6 having a space α is formed between the stamper 5 and the vent 5, and a vent 7 having a space β is formed between the stamper and the outer peripheral pressing ring.

In the disk substrate molding die configured as described above, injection compression molding is generally performed in which the mold clamping force is changed after the injection filling and the mold is slightly opened.

If the intervals α and β of the vents 6 and 7 are too large, burrs occur on the disk substrate, and if they are too narrow, various molding defects and galling occur due to insufficient gas escape, so it is necessary to set them accurately.

[0008]

In the above-mentioned mold for molding a disk substrate, the temperature of the mirror surfaces 11,21 is adjusted by supplying and circulating a temperature adjusting medium to the temperature adjusting grooves 16,27 of the mirror blocks 12,22. However, since the temperature of the outer peripheral pressing ring 5 is due to the heat transfer from the mirror blocks 12 and 22, the temperature of the outer peripheral pressing ring 5 is set to the mirror surfaces 11 and 21 when molding the above-mentioned compact disc having a diameter of 120 mm, for example. It is about 10 ° C lower than the temperature.

In a mold for molding a disk substrate having a diameter D of 120 mm, the size T of the outer peripheral pressing ring 5 shown in FIG. 4 is set to 10 mm, and the interval α between the vents 6 is 15 μm.
, The gap β of the vent 7 is set to 10 μm, the linear expansion coefficient of the outer peripheral pressing ring 5 is set to 11 × 10 ⁻⁶ / ° C., and the temperature difference between the mirror blocks 12, 22 and the outer peripheral pressing ring 5 is set to 1
If the temperature is set to 0 ° C, venting due to thermal expansion during actual molding 6
The change of the interval α of the and the interval β of the vent 7 can be obtained by the following formula. Vent β = 10 mm × 10 ° C. × 11 × 10 ⁻⁶ / ° C. = 0.001 mm = 1 μm Vent α = 120 mm × 10 ° C. × 11 × 10 ⁻⁶ / ° C. = 0.013 mm = 13 μm

The interval β between the vents 7 is 1 μ due to thermal expansion.
There is no big problem because only 10 μm initially set after changing by m becomes 9 μm. However, the interval α of the vent 6 is reduced to 13 μm from the initially set 15 μm due to the difference in thermal expansion between the mirror blocks 12 and 22 and the outer peripheral pressing ring 5 due to the temperature difference of 10 ° C. There was a problem in that various venting defects and galling occurred on the molded disk substrate due to insufficient escape of air generated in the cavity 3 and the gas generated from the molding material because the vent was almost eliminated. Since the difference in the coefficient of thermal expansion in the radial direction due to the temperature difference between the mirror blocks 12 and 22 and the outer peripheral pressing ring 5 is proportional to the diameter of the disk substrate to be molded, for example, the diameter of a video disk with a diameter of 300 mm, When molding a large-sized disk substrate, the vent should be set between the initial setting and the actual molding.
The interval α of changes more greatly.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a die for molding a disk substrate, which can adjust the vent during actual molding to a set interval. Is.

Another object of the present invention is to prevent molding defects such as burrs and galling on the disk substrate by enabling adjustment of the vent during actual molding.

[0013]

In order to solve the above problems, a disk substrate molding die according to the present invention is a fixed die having a mirror surface, and can be moved back and forth with respect to the fixed die. A movable die having a mirror surface opposite to the mirror surface of the fixed die, and a stamper at least the outer peripheral edge of which is held on the mirror surface of either the fixed die or the movable die by an outer peripheral pressing ring; A mold for forming a disk substrate, comprising a temperature adjusting mechanism for the fixed mold and the movable mold, and a vent is formed between the outer peripheral pressing ring attached to one mold and the other mold, The outer peripheral pressing ring is provided with temperature adjusting means.

[0014]

The fixed mold and the movable mold are combined and clamped, and the formed cavity is injection-filled with the molding material that is heated and melted. At this time, the temperature of the mold is adjusted to the optimum temperature for forming the disk substrate by the temperature adjusting mechanism, and the outer peripheral pressing ring is adjusted to the predetermined temperature by the temperature adjusting means. The mold and the outer peripheral pressing ring are thermally expanded by a predetermined amount according to the set temperature, and the interval of the vent formed between the outer peripheral pressing ring attached to one mold and the other mold is adjusted. be able to.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a disk substrate molding die according to the present invention will be described with reference to FIGS. As shown in the cross-sectional view of FIG. 1, the mold for molding a disk substrate includes a fixed mold 1 and a movable mold 2 which are arranged to face each other.
A cavity 3 is formed by clamping the mold 2, and the outer peripheral edge of the stamper 4 is held by either the fixed mold 1 or the movable mold 2 by the outer peripheral pressing ring 5. 4 is held by movable mold 2.

The fixed mold 1 is a fixed platen (not shown).
Fixed plate 10 attached to the
The fixed side mirror block 12 having the mirror surface 11 formed thereon, which is detachably attached to the fixed side mirror block 12, the mescutter 13 provided at the center of the fixed side mirror block 12, and the nozzle (not shown) carried by the mescatter 13 is attached to the fixed side mirror block 12. It is provided with a sprue bush 14 which is brought into contact with and introduces the molten resin into the cavity 3. Note that reference numeral 15 in FIG. 1 indicates a locate ring.

The fixed-side mirror block 12 is formed with a groove 16 which is opened on the surface opposite to the mirror surface 11, and a cover plate 17 is attached so as to seal the open portion of the groove 16 in a watertight manner, and is attached on the outer periphery thereof. The frame 18 is fitted. Cover plate 17
The temperature control medium such as steam, heating oil, or cooling water is supplied and circulated to the groove 16 whose opening is watertightly closed by the groove 16 and constitutes a temperature control mechanism of the fixed mold 1. Fixed side mirror block 12
The outer circumference 11a of the mirror surface 11 is formed in a tapered shape.

The movable mold 2 has a movable plate 20 attached to a movable plate (not shown) which can move back and forth with respect to the fixed mold 1, and a mirror surface 21 detachably attached to the movable plate 20. And a movable mirror block 22 in which the ejector pin 23, the punch 24, and the ejector sleeve 25 are inserted in the center of the insert 26 so as to project therefrom.

The movable-side mirror block 22 is, like the fixed-side mirror block 12, a groove opened to the surface opposite to the mirror surface 21.
27 is formed, a cover plate 28 is attached so as to seal the open portion of the groove 27 in a watertight manner, and the fixed mold 1 is attached to the outer periphery thereof.
A mounting frame 29 formed so as to be aligned with the mounting frame 18 is fitted. The groove 27, whose opening is watertightly closed by the cover plate 28, supplies and circulates a temperature control medium such as steam, heating oil or cooling water to form a temperature control mechanism of the movable mold 2.

The stamper 4 has its inner peripheral edge held by the stamper holder 32, and its outer peripheral edge held by the outer peripheral pressing ring 5, whereby the movable side mirror block of the movable mold 2 is held.
It is detachably attached to the mirror surface 21 of 22.

The stamper holder 32 has a stamper on the outer circumference of the tip.
A flange portion for pressing the inner peripheral edge of 4 is formed, and a screw portion 34 that is screwed into a screw 33 is formed at the base end portion because a bevel gear of a stamper holder holding device (not shown) is provided. And is fitted over the insert 26. Stamper holder
The screw 32 holds the inner peripheral edge of the stamper 4 so as to press the inner peripheral edge of the stamper 4 against the mirror surface 21 of the movable side mirror block 22 by screwing the screw portion 34 into the female screw 33 of the stamper holder holding device. It is removed from the movable mold 2 by releasing the screwing of the stamper holder holding device to the female screw 33.

The outer presser ring 5 has a stamper on its inner circumference.
A claw portion 5a for pressing the outer peripheral edge of 4 is formed and attached to the retainer ring 29 by a bolt 36.
The tip of the claw portion 5a is formed in a tapered shape that is inclined so as to match the tapered outer circumference 11a of the mirror surface 11 of the fixed-side mirror block 12, and the tip of the claw portion 5a and the mirror surface of the fixed-side mirror block 12 are formed. Vents 6 and 7 having predetermined intervals α and β are formed between the tapered outer circumference 11a of 11 and between the claw portion 5a and the surface of the stamper 4 (see FIG. 4).

As shown in FIGS. 3 and 4, on the surface of the claw portion 5a of the outer peripheral pressing ring 5 facing the stamper 4, as shown in FIGS.
An annular groove 40 is formed over the entire circumference, and a micro sheath heater 41 as a temperature adjusting means is attached along the groove 40 in a spiral shape by silver brazing or casting. The connector portion 42 of the micro sheath heater 41 is inserted into a hole penetrating the outer peripheral pressing ring 5 in the radial direction, and one end thereof is connected to a power source (not shown) via a transformer such as a sliderac. . For example, when forming a substrate of a compact disk with a diameter of 120 mm, 300 to 500 W of electric power is supplied to the microseeds heater to heat the outer peripheral pressing ring 5 to a predetermined temperature for thermal expansion, and the outer peripheral pressing ring 5 and the fixed side. A vent 6 is formed at a predetermined interval between the mirror surface 11 of the mirror block 12 and the tapered outer circumference 11a.

The disk substrate molding die according to the present invention is
The temperature adjusting means provided on the outer peripheral pressing ring is not limited to the above-described embodiment, as long as it can heat the outer peripheral pressing ring 5 to a predetermined temperature so that the vents 6 can be arranged at predetermined intervals. For example, the temperature adjusting groove may be formed in the outer peripheral pressing ring to circulate and supply the heat medium. Further, in this embodiment, the stamper 4 and the outer peripheral pressing ring 5 for holding the stamper 4 are attached to the movable mold 2, but the fixed mold 1 can also be attached.

[0025]

According to the present invention, the thermal expansion of the outer peripheral ring can be adjusted by providing the outer peripheral pressing ring with the heating means as described above, and the interval of the vent during the actual molding can be adjusted. Therefore, it is possible to obtain an effect such that it is possible to prevent a molding defect such as a burr that occurs when the interval between the vents is too large, or a galling that occurs when the vent interval is too narrow. .

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view of a disk substrate molding die.

FIG. 2 is an enlarged sectional view of a main part of a disk substrate molding die according to the present invention.

FIG. 3 is a sectional front view showing a part of an outer peripheral pressing ring of a disk substrate molding die according to the present invention.

FIG. 4 is an enlarged view of a main part showing a vent.

[Explanation of symbols]

 1 Fixed mold 2 Movable mold 3 Cavity 4 Stamper 5 Outer peripheral pressing ring 11 Mirror surface 16 Temperature adjusting groove (temperature adjusting mechanism) 21 Mirror surface 27 Temperature adjusting groove (temperature adjusting mechanism) 41 Micro sheath heater (temperature adjusting means)

Claims (1)

[Claims] 1. A fixed mold having a mirror surface, and a movable mold having a mirror surface which is provided so as to be able to approach and retreat with respect to the fixed mold and has a mirror surface facing the mirror surface of the fixed mold. A stamper having an outer peripheral edge held on a mirror surface of one of a fixed mold and a movable mold by an outer peripheral pressing ring, and a temperature adjusting mechanism for the fixed mold and the movable mold are provided, and the stamper is attached to one mold. A disk substrate molding die in which a vent is formed between the outer peripheral pressing ring and the other die, wherein the outer peripheral pressing ring is provided with temperature adjusting means.