JP2592092B2 - Optical disc manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing an optical disk.

[Conventional technology]

Conventionally, injection molding of a disk substrate of an optical disk requires machining of a center hole in some process during molding of the substrate, and the hole machining is performed after the injection of the disk substrate is completed as shown in FIGS. The process has been performed within the substrate, or taken out of the mold after the completion of the injection of the disk substrate, until the substrate protective film forming step. This is because the next step of the disk substrate injection molding process is the formation of a substrate protective film, so if the central hole is not processed as shown in FIGS. This is because it hinders the formation of the protective film, and significantly lowers the productivity.

[Problems to be solved by the invention]

However, if the hole processing is performed in the mold after the injection is completed,
As shown in FIG. 9, burrs and chips are likely to adhere to the disk substrate before the formation of the substrate protective film when drilling holes, and the performance of the metal protective film is significantly reduced by the adhered substance. In addition, when drilling is performed in the mold, chips are adhered to the molding surface of the mold as shown in FIG. 13, thereby avoiding the inconvenience that molding defects occur on the disk substrate formed in the next cycle shot. Absent.

[Object of the invention]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to prevent chips from adhering to a disk substrate before a substrate protective film forming step and to obtain a high quality disk substrate.

[Means for solving the problem]

An optical disk manufacturing method according to the present invention is directed to a method for manufacturing an optical disk in which a resin is injected into a disk-shaped cavity and then a sprue / runner is cut to form a central hole of a disk substrate. In addition, a part of the sprue / runner is cut and removed, and then, after forming a substrate protective film, the gate is cut to separate the runner.

〔Example〕

First, an example of the apparatus for carrying out the method of the present invention is shown in FIGS.
Description will be given along the figure.

In FIG. 1, reference numeral 1 denotes a substrate protective film forming apparatus, 2 denotes a gate cutting apparatus, 3 denotes a tray cleaning apparatus, and 4 denotes a substrate which is sequentially transported to the substrate protective film forming apparatus 1, the gate cutting apparatus 2, and the tray cleaning apparatus 3. It is a closed loop tray transport device. Reference numeral 6 denotes an injection molding machine, which injects a disk substrate 7 by injection molding, and after injection is completed, a sprue / runner molded together with the disk substrate 7
Part 28a of 28 is removed. Reference numeral 8 denotes a molded article transfer device such as a robot, which is a part of the sprue / runner 28 from the injection molding machine 6.
The disk substrate 7 from which the 28a has been removed is taken out and supplied to the entrance side of the substrate protective film forming apparatus 1 in the tray transport device 4. Reference numeral 9 denotes a product take-out device such as a robot which forms the substrate protective film 30 and cuts the gate 50 to remove the residual runner 28.
It is provided to take out the disk substrate 7 from which b has been removed.

The substrate protective film forming apparatus 1 is an Al sputtering apparatus or the like, which is a vacuum evaporation apparatus.
Are continuously provided before and after the sputtering chamber 11, and an Al film as a substrate protective film is formed on the disk substrate 7 in the sputtering chamber 11.

The mold apparatus of the injection molding machine 6 will be described with reference to FIG. 2. In the figure, reference numeral 12 denotes a fixed mold, and a fixed platen 13 is attached to a mounting plate 14.
Is mounted via. Reference numeral 1 denotes a sprue bush, which is slidably fitted into the mounting plate 14 and has a fixed platen 13.
It is resiliently supported on the side via a spring 16. The sprue bush 15 is slidably fitted in a through hole 17 formed in the center of the fixed mold 12. Reference numeral 18 denotes a movable mold, which is mounted on a movable platen 19 via a mounting plate 20. Reference numeral 21 denotes a punch mounted on the piston 22 and slidably fitted in a through hole 23 formed in the center of the movable mold 18. Reference numeral 24 denotes an annular cavity, which is formed by the fixed mold 12 and the movable mold 18 which are clamped by a mold clamping device (not shown). The sprue bush 15 and the punch 21 are arranged at the center of the substrate center hole forming portion surrounded by the cavity 24 and face each other. 25 is an ejector pin,
It is slidably fitted into the sprue bush 15 and the punch 21 and is urged by a spring 26 to return. 27 is a nozzle of the plasticizer.

When practicing the present invention using the above device,
According to the following steps.

(1) A molten resin is injected from a nozzle 27 through a sprue / runner 28 and a gate 50 into a cavity 24 formed by clamping the fixed mold 12 and the movable mold 16 to each other to perform pressure-holding and cooling to form an optical disk. The disk substrate 7 is formed (see FIG. 3).

(2) When the nozzle 27 is retracted while holding the mold clamping force, the sprue bush 15 is stationary at the position shown in the left half of FIG. Next, when the punch 21 is raised by the cylinder 29 built in the mounting plate 20 via the piston 22, the punch 21, the sprue bush 15 and the resin portion sandwiched therebetween are integrally formed as shown in the right half of FIG. When the upper end of the punch 21 reaches the inner peripheral edge of the through-hole 17 of the fixed mold 12 and moves by overcoming the spring force pressing the bush 15, a part 28a of the sprue runner located at a position away from the gate 50 is reached. Is cut and removed (see FIG. 4). Note that, in order to prevent generation of chips in the gate cut in the subsequent step, it is preferable to perform preliminary gate cut simultaneously so that the gate 50 faces the axial end of the inner peripheral surface of the cavity.

(3) After cutting and removing a part 28a of the sprue runner 28, the mold clamping force is released to open the mold, and the disk substrate 7 is taken out. The disk substrate 7 is transferred to a tray by the molded product removal device 8 and sent to the substrate protective film forming device 1 by the tray transport device 4 to form a substrate protective film (Al film) 30 on the disk substrate 7 (FIG. 5). reference).

(4) The residual runner 28b is cut off from the disk substrate 7 by gate cutting by the gate cutting device 2 (see FIG. 6). The disk substrate 7 is taken out of the tray 5 by the product take-out device 9. After the tray 5 is taken out of the disk substrate 7, the Al film adhered from the surface thereof is removed by the tray cleaning device 3, and the tray 5 is circulated and reused.

〔The invention's effect〕

As described above, according to the present invention, since a part of the sprue runner is cut and removed before forming the protective film on the disk substrate, the substrate protective film can be easily formed without disturbing the sprue. Further, since a part of the sprue runner is cut off at a position away from the gate, chips do not adhere to the surface of the disk substrate and the molding surface of the mold.

Therefore, a high quality optical disk can be manufactured with high productivity.

[Brief description of the drawings]

FIG. 1 is a plan view showing an outline of an apparatus for carrying out the present invention, FIG. 2 is a sectional view showing a main part of an injection molding machine in the apparatus, and FIG.
FIGS. 4, 4, 5 and 6 are process diagrams of the method of the present invention, FIGS. 7, 8 and 9 are process diagrams of a conventional example, and FIG. Indicates adverse effects. Fig. 10, 11
FIG. 12 is a process chart of another conventional example, and FIG. 13 is a schematic view corresponding to FIG. 9, showing the adverse effect of chips on the formation of a disk substrate. 7 ... Disc substrate, 28 ... Sprue runner, 30 ...
... Substrate protective film, 50 ... Gate.

Claims (2)

(57) [Claims] In a method for manufacturing an optical disk, wherein a resin is injected into a disk-shaped cavity, and a sprue / runner is cut off to form a central hole of a disk substrate, a sprue is cut before cutting a gate connecting the runner and the cavity. A method for manufacturing an optical disk, comprising cutting off a part of the runner, forming a substrate protective film, and then cutting the gate to separate the runner. 2. A method for manufacturing an optical disk according to claim 1, wherein before forming the substrate protective film, preliminary cutting is performed so that the gate faces an axial end of the inner peripheral surface of the cavity. .