JPS6235820A - Optical disc mold - Google Patents

Abstract

PURPOSE:To obtain an optical disc mold of excellent adherence between a stamper and the movable side, by a method wherein the mirror-finished part of either one with which the stamper is provided so as to go along, of the fixed side or the movable side is magnetized. CONSTITUTION:A mirror plate 5 is magnetized with the preferable magnetic flux density of about 60 Gauss. As for the materials for the mirror plate 5 and for a stamper 6, any magnetic material can be employed fittingly. However, normally, Ni is used as the material for the stamper 6. When the stamper 6 is intended to be mounted to the mirror plate 5, firstly movable side fixing ring 8 and a holder 11 are dismantled from the force side part 4 of a mold. Secondly, the stamper 6 is attracted to the mirror plate 5. Thirdly, the holder 11 and movable side fixing ring 8 are respectively fitted to a mounting hole 9 and an annular groove 7. After the injection and solidification of resin, the hydraulic cylinder is operated so a fixed plate 1 and the fixed side 2 of the mold are parted so as to take a sprue out of the mold and, after that, to cut off the sprue by advancing a punch 12 by means of a hydraulic cylinder.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an injection molding machine, and particularly to an optical disc mold used for molding an optical disc.

(Prior Art) When molding an optical disk, a stamper is generally attached to a movable mold, but in the past, this stamper was only fixed mechanically.

(Problems to be Solved by the Invention) In the conventional example as described above, the stamper may not come into close contact with the movable mold, and may float on the stamper.

This will result in some areas. When the cavity is filled with molten resin in this state, the air between the stamper and the movable mold is adiabatically compressed, causing a mist-like pattern to appear on the molded product.
There was a problem.

The present invention was made to solve this problem, and an object of the present invention is to obtain an optical disc mold with good adhesion between a stamper and a movable mold.

(Means for Solving the Problems) The present invention is to magnetize the mirror surface portion of either the fixed mold or the movable mold to which the stamper is attached.

(Function) Since the mirror surface of either the stationary mold or the movable mold is magnetized, the stamper is attracted to the mirror surface, improving adhesion.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a fixed mold 2 is attached to the fixed plate 1, and a movable mold 4 is attached to the movable plate 3. A mirror-finished mirror plate 5 is attached to the bottom of the movable mold 4, and a stand bar 6 is attached along the mirror plate 5, as shown in FIG. Further, an annular groove 7 is formed around the mirror plate 5 so as to surround it, and a movable side fixing ring 8 is fitted into the groove 7. The fixing ring 8 is formed with an annular claw 8a, and the peripheral edge of the stand bar 6 is
It is pressed and fixed to the mirror plate 5 by the claws 8a. A mounting hole 9 passing through the mirror plate 5 is formed in the center of the mirror plate 5, and a holder 11 having a holding claw 11a at the tip thereof is fitted into the mounting hole 9. The tip of the holder 11 slightly protrudes from a through hole 12 formed in the center of the stand bar 6, and the holding claw 11a presses and fixes the center of the stand bar 6 to the mirror plate 5.

In Fig. 1 and Fig. Em2, 12 is a punch for cutting the sprue, 13 is a sprue ejector that can freely protrude from the end face of the punch 12 for ejecting the sprue, and 14 is a sprue ejector that penetrates through the center of the sprue ejector 13 and has a rear end attached to the punch 12. Fixed sprue gripping rod.

In the above, a case has been described in which the fixing ring 8 that presses the outer periphery of the stand bar 6 is provided, but the present invention is not limited to this, and the fixing ring 8 may not be provided as shown in FIG. 3.

Furthermore, what is important in the present invention is that the mirror plate 5 is made magnetic. As for the magnetic flux density, data was obtained from the results of experiments taking into consideration the attachment, detachment, and adsorption properties of the stand bar 6, that it is preferable to set the magnetic flux density to about 60 Gauss. The materials for the mirror plate 5 and the stand bar 6 may be appropriately selected as long as they are magnetic, but the material for the stand bar 6 is usually Ni.

Next, to describe the case where the stand bar 6 is attached to the mirror plate 5, the movable side fixing ring 8 and the holder 11 are removed from the movable side mold 4, the stand bar 6 is adsorbed to the mirror plate 5, and then the holder 1 and the movable side The fixing ring 8 is fitted into the mounting hole 9 and the annular groove 7, respectively. In the conventional example, when attaching the stand bar 6 using the holder 1 and the movable fixing ring 8, or when taking out the molded product by protruding it, air enters between the stand bar 6 and the mirror plate 5.
In the next cycle, this intruding air was adiabatically compressed.

After injection, after the resin has solidified, the sprue is ground out by activating a hydraulic cylinder (not shown) to separate the fixed plate l and the stationary mold 2, and then the punch 12 is moved forward by the hydraulic cylinder (not shown). Cut the sprue. The cut sprue is securely held by one gripping rod 14.

(Effects of the Invention) As is clear from the above, the present invention is a C in which the mirror surface portion to which the stand bar is attached is made magnetic, so that the stand bar is in close contact with the mirror surface portion, and therefore the stand bar and the mirror surface portion are magnetized. Almost no air enters between the molded product and the mirror surface portion, so that any adverse effects on the molded product caused by adiabatic compression of air, as in the conventional example, are completely eliminated.

In addition, conventionally, it was necessary to perform hundreds of injections to obtain a good product, but with the present invention, a good product can be obtained with just a few injections, which improves product yield and productivity. improves.

Furthermore, since adiabatic compression of air does not occur, the life of the standber is extended, and the cost of the standber can therefore be reduced.

[Brief explanation of drawings]

2...Fixed side mold 4...Movable side mold 5... Mirror plate 6... Standby Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] An optical disk mold characterized in that a mirror surface portion of either a fixed mold or a movable mold to which a stamper is attached is magnetized.