JPH01258924A - Method of manufacturing optical disc - Google Patents

Abstract

PURPOSE:To obtain a high quality disc substrate without adhering chips by a process wherein, upon manufacturing an optical disc by injection molding, the part of a spool runner is cut-removed before cutting the gate communicating the runner and cavity, and after forming a substrate protecting film is formed, the separation of the runner is carried out through cutting the gate. CONSTITUTION:After molding an optical substrate 7, as a punch 21 is moved up and the upper end of the punch 21 reaches the inner peripheral edge part of a through hole 17 of a fixing side die 12, the part 28a of spool runner spaced apart away from a gate 60 is cut-removed. After that, the disc substrate 7 is taken out through an opening die and a substrate protecting film 30 is formed on the disc substrate 7. Following this, the remaining runner 28b is cut-removed from the disc substrate 7 through gate cutting. Inasmuch as in this manner, the part of the spool runner is cut-removed at the positions spaced apart away from the gate prior to the formation of the disc substrate protecting film, the chips do not adhere the surface of the disc substrate and a high quality molding article is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing an optical disc.

[Conventional technology]

Conventionally, injection molding of disk substrates for optical disks requires machining of a center hole at some stage during the substrate molding process, and the hole machining is performed after injection of the disk substrate is completed, as shown in FIGS. 7 to 9. Either the process is carried out while the disk substrate is still in the mold, or it is taken out of the mold after the injection of the disk substrate is completed and the process is carried out before the process of forming the substrate protective film. This is because the next step after the disk substrate injection molding process is the formation of a substrate protective film, so if the center hole is left unprocessed as shown in Figures 10 to 12, the sprue etc. will occupy a large space and the substrate will It becomes a special hindrance to the formation of the protective film.
This is because productivity will drop significantly.

[Problem to be solved by the invention]

However, the hole machining is done in the mold after the injection is completed.

If this is done, as shown in FIG. 9, during hole drilling, particles and chips tend to adhere to the disk substrate before the substrate protective film is formed, and the performance of the metal protective film is significantly degraded by the deposits. In addition, when drilling a hole in a mold, as shown in Figure 13, it is possible to avoid the inconvenience of chips adhering to the molding surface of the mold and causing molding defects in the disk substrate molded in the next shot cycle. do not have.

[Purpose of the invention]

The present invention has been made to solve the above problems,
The purpose is to prevent chips from adhering to a disk substrate before a step of forming a substrate protective film, and to obtain a disk substrate of good quality.

[Means to solve the problem]

The optical disc manufacturing method of the present invention includes injection molding a resin into a disc-shaped cavity, and then cutting off a sprue runner to form a central hole in a disc substrate. The method is characterized in that a part of the sprue runner is first cut and removed, then a substrate protective film is formed, and then the gate is cut and the runner is separated.

[Example] First, an example of an apparatus for implementing the method of the present invention will be described with reference to FIGS. 1 and 2.

In FIG. 1, 1 is a substrate protective film forming device, 2 is a gate cutting device, 3 is a tray cleaning device, and 4 is the substrate protective film forming device 1.
Then, the tray 5 is sequentially transferred to the gate cutting device 2 and the tray cleaning device 3.
This is a closed-loop tray conveying device that conveys. 6 is an injection molding machine which injection molds the disk substrate 7, and after the injection is completed, the sprue runner 2 is molded together with the acid disk substrate 7.
Part 28a of 8 is removed. Reference numeral 8 denotes a molded product transfer device such as a robot, which takes out the disk substrate 7 after removing a portion 28a of the sprue runner 28 from the injection molding machine 6 and transfers it to the tray conveyance device 4 on the inlet side of the substrate protective film forming device 1. supply to. Reference numeral 9 denotes a product take-out device such as a robot, which is provided to take out the disk substrate 7 on which the substrate protection film 30 has been formed, the gate 50 has been cut, and the remaining runners 28b have been removed.

The substrate protective film forming apparatus 1 is a vacuum evaporation apparatus A1. This is a sputtering device or the like, and a vacuum preparatory chamber 10 is installed in front and behind a sputtering chamber 11 when viewed in the tray transport direction, and a substrate protective film Ai is formed on the disk substrate 7 in the sputtering chamber 11.

The mold device of the injection molding machine 6 will be described with reference to FIG. 2. In the figure, reference numeral 12 denotes a stationary side mold, which is attached to a stationary platen 13 via a mounting plate 14. A sprue bush 15 is slidably fitted into the mounting plate 14 and resiliently supported on the fixed platen 13 side via a spring 16. This sprue bush 15 is attached to the fixed side mold 1.
It is slidably fitted into a through hole 17 bored in the center of 2. On the 1st, on the movable side mold, attach the mounting plate 2 to the movable platen 19.
It is attached via 0. A punch 21 is attached to the piston 22 and is slidably fitted into a through hole 23 formed in the center of the movable mold 18.

Reference numeral 24 denotes an annular cavity, which is formed from the fixed side mold 12 and the movable side mold 18, which are clamped by a mold clamping device (not shown). The sprue bush 15 and the punch 21 are arranged in the center of the substrate center hole molding portion surrounded by the cavity 24, and are opposed to each other. Reference numeral 25 denotes an ejector bin, which is slidably fitted into the sprue bush 15 and punch 21, and is biased with a return force by a spring 26. 27 is a nozzle of a plasticizing device.

When carrying out the present invention using the above-mentioned apparatus, the following steps are performed.

(1) Molten resin is injected through a nozzle 27 through a sprue runner 28 and a gage 1-50 into a cavity 24 formed by clamping the fixed mold 12 and the movable mold 16, and is kept under pressure and cooled. The disk substrate 7 of the optical disk is molded (see FIG. 3).

(2) When the nozzle 27 is moved backward while the mold clamping force is maintained, the sprue bush 15 remains stationary at the position shown in the left half of FIG. 2 only by the force of the spring 16. Next, the piston 2 is moved by the cylinder 29 built into the mounting plate 2o.
2, the punch 21, the sprue bush 15, and the resin portion sandwiched therebetween are integrated into the sprue bush 15, as shown in the right hand side of FIG.
When the upper end of the punch 21 reaches the inner peripheral edge of the through hole 17 of the stationary mold 12, the part 28a of the sprue runner located away from the gate 50 moves. It is cut and removed (see Figure 4).

In order to prevent the generation of chips during gate cutting in the subsequent process, it is preferable to perform preliminary gate cutting at the same time so that the gate 50 faces the axial end of the inner circumferential surface of the cavity.

(3) After cutting and removing the part 28a of the sprue runner 28, the mold clamping force is released and the mold is opened, and the disk substrate 7 is removed.
Take out. This disk substrate 7 is removed by a molded product take-out device 8.
The disk substrate 7 is transferred to a tray and fed into the substrate protective film forming apparatus 1 by the tray transport device 4 to form a substrate protective film CAR film 30 on the disk substrate 7 (see FIG. 5).

(4) Cut and remove the remaining runner 28b from the disk substrate 7 by gate cutting using the gate cutting bag W2 (see FIG. 6). This disk substrate 7 is taken out from the tray 5 by a product take-out device 9. Further, after the disk substrate 7 is removed from the tray 5, the /l film adhering to its surface is removed by the tray cleaning device 3, and the tray 5 is recycled and reused.

〔Effect of the invention〕

As described above, the present invention cuts and removes a portion of the sprue runner before forming the protective film on the disk substrate, so that the substrate protective film can be easily formed without being hindered by the sprue. Furthermore, since a portion of the sprue runner is cut and removed at a position away from the gate, chips will not adhere to the surface of the disk substrate or the molding surface of the mold.

Therefore, high-quality optical discs can be manufactured with high productivity.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an overview of the apparatus for implementing the present invention, FIG. 2 is a sectional view showing the main parts of the injection molding machine in the same apparatus, and FIG.
4, 5, and 6 are process diagrams of the method of the present invention, and Figures 7, 8, and 9 are process diagrams of the conventional method. Indicates the negative impact it has. Figure 10, 1st
Figures 1 and 12 are process diagrams of other conventional examples, and Figure 13 is the process diagram of the 9th example.
FIG. 2 is a schematic diagram showing the adverse effect that chips have on the molding of a disk substrate, corresponding to the figure; 7... Disk substrate, 28... Sprue runner, 30... Substrate protective film, 50... Gate. Figure 1 Figure 3 Figure 4 Preliminary gate (molding) Figure 7 Figure 10 (molding) Figure 5 Figure 6 (protective film formation) (Gate cutting) Figure 8 Figure 9 Figure 11 Figure 12

Claims (2)

[Claims] (1) After injection molding the resin into the disc-shaped cavity,
In an optical disk manufacturing method in which a sprue runner is cut off to form a center hole in a disk substrate, a part of the sprue runner is cut and removed before cutting a gate communicating between the runner and the cavity, and then a substrate protective film is formed. A method for manufacturing an optical disc, which comprises: cutting the gate and separating the runner after performing the above steps. (2) The method for manufacturing an optical disk according to claim 1, wherein the substrate is pre-cut so that the gate faces the axial end of the inner circumferential surface of the cavity before forming the substrate protective film.