JPH0375022B2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a mold for a disk base, and particularly to an injection compression mold.
The present invention relates to a disk base mold suitable for use in molding.

(Prior Art) Disc bases such as optical disc bases such as video discs and compact discs are usually manufactured by injection molding. In general, the injection molding includes a fixed mold and a movable mold in which a predetermined stamper is set by inner and outer stamper holding members, and which is moved toward and away from the fixed mold. is used. By injecting and molding a predetermined resin material into a product cavity formed between the molds of such a mold, a disk base onto which the information of the stamper is transferred is manufactured.

By the way, in such a molding die for a disk base, since it is necessary to mold the disk base with good dimensional accuracy, the fixed mold and the movable mold are adjusted to have high precision when closing the mold where the product cavity is formed. It is necessary to position it well. Therefore, in such molds, tapered surfaces that correspond to each other are usually provided on the outer periphery of the fixed mold and the movable mold, and the molds are aligned by taper fitting of these tapered surfaces. things are being done.

(Problem) However, in conventional molds for disk bases, these tapered surfaces are provided in a fixed position relative to the cavity members that form the product cavity of each mold (fixed mold and movable mold), and the mold When the mold is closed, they are fitted to provide a core-insulating function, but when the mold is opened, they are not fitted and the core-insulating function is not achieved. When pressing (compressing) after injecting the resin material into the product cavity (see item 1), the cavity member on the fixed mold side may come into contact with the inner circumferential surface of the outer stamper holding member at the peripheral edge of the cavity surface, causing it to snap. There was a problem that the life of the mold was shortened due to the galling phenomenon.

That is, the mold clamping device of an injection molding machine in which such a mold for a disk base is used generally includes a fixed platen 12 to which a fixed mold 10 is attached and a movable mold 14, as shown in FIG. It has a structure in which the movable platen 16 to which the movable platen 16 is attached faces horizontally. Then, while the movable platen 16 is guided by the guide rod 20, the ram 18 of the mold clamping cylinder
The molds 10 and 14 are opened and closed by being moved toward and away from the stationary plate 12 as the molds 10 and 14 move forward and backward.

Therefore, when the molds 10 and 14 are opened when the tapered surfaces are in a non-fitting state, the symbols shown in FIG. 4 are as follows:
As shown by θ, due to the existence of a sliding clearance between the movable platen 16 and the guide rod 20, the movable platen 16 and, by extension, the movable mold 14 are slightly inclined toward the fixed mold 10 side. This is unavoidable, and due to the inclination of the movable mold 14, it is unavoidable that the cavity member on the fixed mold 10 side comes into contact with the inner peripheral surface of the outer stamper holding member at the peripheral edge of the cavity surface. be. In particular, the molds 10 and 14 are slightly opened by the injection operation of the resin material of the product cavity, and after the resin material is injected, the movable mold 14 is pushed out to the mold closing position and a clamping operation is performed. In the injection compression molding that is carried out, the movable mold 14 is held in an inclined state by the resin material injected into the product cavity, that is, the peripheral edge of the cavity surface of the cavity member on the fixed mold 10 side is turned outward. Since there is a tendency for the pressing operation after injection to be forcibly performed while the stamper holding member remains in contact with the inner circumferential surface, the cavity surface of the cavity member on the fixed mold 10 side is A noticeable galling phenomenon occurred at the periphery.

In addition, when the conventional molding die for disk substrates as mentioned above is used for injection compression molding,
For the same reason as mentioned above, that is, the mold clamping operation after injecting the resin material into the product cavity is performed with the movable mold 14 in an inclined state.
There was also a problem in which the thickness of the disk base, which was a molded product, became thicker at the lower part of the mold (product cavity) where it was molded.

(Solution Means) Here, the present invention has been made against the background of the above-mentioned circumstances, and the gist thereof is to provide a fixed mold as described above, and a method for approaching the fixed mold. A predetermined stamper that is spaced apart includes a movable mold set by inner and outer stamper holding members, and by injecting a predetermined resin material into a product cavity formed between these molds, the information of the stamper is printed. For disk bases, the molds are aligned by tapered fitting of mutually corresponding tapered surfaces provided on the outer peripheries of the fixed mold and the movable mold for molding the disc base onto which is transferred. In the mold, the taper forming member on the fixed mold side or the movable mold side having the tapered surface is moved toward and away from the cavity member on the fixed mold side or the movable mold side. is provided so as to be movable in parallel a predetermined distance, and is provided with an urging means for urging the taper forming member in a direction in which it always protrudes from the cavity member, so that the mold closing position of the mold and the movable mold are aligned with each other. The tapered surfaces of these molds are held in a fitted state that keeps the molds centered between the mold closed position and the position where the molds are moved a predetermined distance in the mold opening direction.

(Function/Effect) According to such a mold for a disk base, the taper surfaces for centering on the fixed mold and movable mold sides are aligned with the mold closing position of those molds and the movable mold in its mold closing position. The molds are held in a fitted state between the position and the position where they are moved a predetermined distance in the mold opening direction, and during that time the molds are held in an aligned state, so the final stage of the mold closing operation, especially During the mold clamping operation after the injection operation of the injection material into the product cavity in injection compression molding, the movable mold is is held in a non-inclined state (parallel state) with respect to the fixed mold.

In other words, by using the disk base mold according to the present invention, it is possible to effectively avoid the movable mold from being closed while being tilted relative to the fixed mold, and therefore, This effectively prevents the cavity member from coming into contact with the inner circumferential surface of the outer stamper holding member at the peripheral edge of the cavity surface. Therefore, unlike the conventional molds mentioned above, it is possible to effectively prevent the galling phenomenon from occurring due to the contact between the molds when opening and closing the molds.Especially when used for injection compression molding, the mold This makes it possible to significantly improve the lifespan of.

Furthermore, when the mold according to the present invention is used for injection compression molding, the injection material can be injected while the movable mold is held parallel to the fixed mold, and the injection material can be injected in parallel to the fixed mold. Since it is possible to perform the clamping operation after the injection operation while maintaining the state, it is possible to avoid the problem of the movable mold due to the sliding clearance between the movable platen and the guide rod, unlike when using a conventional mold. There is no unevenness in the thickness of the molded product due to the inclination, and therefore there is an advantage that a disk base of better quality than before can be molded.

(Example) Hereinafter, in order to clarify the present invention more specifically, one example thereof will be described in detail based on the drawings. In addition, since the mold of this example is used in a mold clamping device similar to that in which a conventional mold is used, the configuration of the mold clamping device will be explained with reference to FIG. 4. .

First, FIG. 1 shows a sectional view of essential parts of a mold for a disk base according to the present invention in a closed state. Here, 22 and 24 are a fixed mold and a movable mold constituting the mold of this embodiment, and the corresponding surfaces are mirror surfaces 26 and 28, respectively.
mirror blocks 30, 32 as cavity members, and mirror blocks 30, 32
It is configured to include mold bodies 34 and 36 that hold the mold bodies. When the mold bodies 34 and 36 are brought into contact with each other at the outer portions of the mirror blocks 30 and 32 during mold closing, a product cavity 38 is formed with a predetermined gap between the mirror blocks 30 and 32.
is beginning to form. Note that the mirror surface 28 of the movable mirror block 32 has an inner stamper holding member (not shown) and an outer stamper holding member 40 on the inner and outer peripheries, respectively, as in the conventional mold.
A donut-shaped stamper 42 is provided, which is held by a donut-shaped stamper 42 and has a predetermined information pattern engraved thereon.
The information pattern of the stamper 42 is transferred to a disk substrate such as an optical disk substrate molded in the product cavity 38.

More specifically, each of the mold bodies 34 and 36 of the molds 22 and 24 has concentric circular recesses 44 and 46 having approximately the same diameter and a predetermined depth, respectively, located at opposing portions thereof. and those circular recesses 44, 46
It has annular flat surfaces 48 and 50 that are located at the opening periphery of the molds 22 and 24 and face each other in the opposite direction of the molds 22 and 24. Then, as shown in the figure, mold 2
When the molds 2 and 24 are closed, those mold bodies 3
The annular planes 48, 50 of 4, 36 are brought into abutment with each other.

On the other hand, the mirror blocks 30 and 32 are both substantially disk-shaped with a predetermined thickness, and are disposed in circular recesses 44 and 46 of mold bodies 34 and 36, respectively. And mold body 3
4 and 36 are brought into contact with the annular planes 48 and 50 during mold closing, the mirror surfaces 2 facing each other
6, 28, and even the mirror surface 26 on the fixed mold 22 side
A predetermined gap is formed between the stamper 42 and the stamper 42 disposed on the mirror surface 28 on the movable mold 24 side.

Further, each mirror block 30, 32 is provided with an annular notch that defines the outer periphery of the mirror surfaces 26, 28, and when the molds 22, 24 are closed, these notches are formed. As a result, an annular space is formed. The outer stamper holding member 40 is attached to the mirror block 32 on the movable side in such a manner that it is housed in the annular space, and an annular protrusion 56 formed on the inner circumferential surface of the outer stamper presser member 40 is attached to the movable mirror block 32 so that the outer circumference of the stamper 42 is restrained to the mirror block 32. As shown in FIG. 1, when the mold is closed, the space between the mirror blocks 30 and 32 is pressed against the inner peripheral surface 58 of the annular projection 56 of the outer stamper holding member 40. The product cavity 38 is adapted to be defined thereby forming the product cavity 38.

Here, the annular projection 5 of the outer stamper holding member 40 that defines the outer periphery of the product cavity 38 is
The inner circumferential surface 58 of the fixed mirror block 30 and the annular stepped portion 60 surrounding the mirror surface 26 of the fixed mirror block 30 are tapered surfaces that correspond to each other, and as shown in FIG. , 24 are closed in a molded state, a predetermined minute gap is formed between them. In addition, the molds 22, 2
When the mold 4 is closed, a predetermined minute gap is also formed between the opposing surfaces of the annular notch of the outer stamper holding member 40 and the fixed mirror block 30. As a result, the outer stamper holding member 40 and the fixed mirror block 30 are prevented from interfering with each other, and gas in the product cavity 38 is vented through the gap during injection molding. There is.

By the way, such molds require high dimensional accuracy for the disk base, which is the molded product.
When closing the mold, it is necessary to accurately position the fixed mold 22 and the movable mold 24. However, like molds that use the conventional taper fitting mechanism,
If the core alignment state of the molds 22 and 24 is to be ensured only when the molds 22 and 24 are closed, the molds 22 and 24
When the mold is opened and closed, due to the inclination of the movable mold 24 based on the sliding clearance between the movable platen 16 and the guide rod 20, the peripheral edge of the mirror surface 26 of the fixed side mirror block 30 touches the inner peripheral surface of the outer stamper holding member 40. Particularly during injection compression molding, when the mold is clamped (compressed) after the injection material is injected, it is unavoidable that galling occurs at the abutting portion. In addition, in injection compression molding, the movable mold 24 tends to be held in an inclined state by the resin material injected into the product cavity 38, so the movable mold 24 remains in an inclined state. When the above-mentioned pressing operation is performed, there is a problem in that the thickness of the molded disk base becomes uneven.

Therefore, in this embodiment, the mold body 34,
A taper fitting mechanism as described below is provided at the outer periphery of the annular planes 48, 50 of the molds 22, 24, and the molds 22, 24 are arranged in a closed position.
4 and the position where the mold opens to a predetermined dimension, the molds 22 and 24 are precisely aligned by the taper fitting mechanism, thereby preventing the above-mentioned problems. Efforts are being made to resolve the issue.

That is, in the mold of this example, the first
As shown in the figure, on the fixed mold 22 side, the outermost periphery of the mold body 34 is connected to the annular plane 48.
The inner peripheral surface of the annular notch is formed into a tapered surface 62 having a predetermined inclination angle, so that the tapered surface 62 is shaped like a mold main body 34 as in the conventional mold. is integrally formed.
However, on the movable mold 24 side, as shown in FIG. 1, a tapered surface 64 that fits with the tapered surface 62 on the fixed mold 22 side is not directly formed on the mold body 36. First, an outer peripheral ring 66 is provided as a taper forming member separately from the mold body 36.
It is formed on the inner peripheral surface of.

This outer circumferential ring 66 has a substantially cylindrical shape, and the tip side of its inner circumferential surface (fixed mold 22 side)
is a tapered surface 64 as described above, but the proximal end side is a cylindrical surface 68, and as shown in the figure, the stepped portion provided on the outer periphery of the movable mold body 36 The cylindrical surface 68 is slidably fitted to the cylindrical surface 70 . And here,
Both cylindrical surfaces 68 and 70 are machined with high precision to minimize the sliding clearance between them so that the outer ring 66 can move in the axial direction while maintaining high parallelism. It is being done. The outer ring 66 has a cylindrical surface 68 having the same length as the cylindrical surface 70 of the mold body 36, and when the molds 22 and 24 are closed, the cylindrical surface 68 has the same length as that shown in FIG. Tapered surface 6
The annular flat surfaces 48 and 50 of the mold bodies 34 and 36 are allowed to come into contact with each other while maintaining the fitted state of the mold bodies 2 and 64.

The outer circumferential ring 66 has a plurality of large-diameter portions 72 located at appropriate positions in the circumferential direction and penetrating in the axial direction, each having an opening on the distal end side having a large diameter over a predetermined length. A through hole 74 is formed. On the other hand, the stepped surface 76 of the movable mold body 36 on which the outer ring 66 is seated has a stepped surface 76 having a predetermined depth, located at a portion corresponding to the formation portion of each through hole 74 of the outer ring 66. A bottom hole 78 is formed. As shown in FIG. 1, each through hole 7 of the outer ring 66
4, a sliding sleeve 82 having an outward flange portion 80 at one end in the axial direction is connected to the large diameter portion 7.
The outer circumferential ring 66 is attached to the mold body 36 by being inserted from the second side and by standing the sliding sleeve 82 at the bottom of the bottomed hole 78 with bolts 84. In this embodiment, the outer circumferential ring 6 is the distance along its axis: α (usually,
It is designed to be able to move by about 1 to 2 mm).

Further, as shown in FIG. 1, a compression coil spring 86 is disposed in each bottomed hole 78 in a state that it is inserted into a sliding sleeve 82, and the outer peripheral ring 66 is connected to the compression coil spring 86. It is always biased toward the tip side, that is, toward the fixed mold 22 side by the coil spring 86. In this embodiment, this compression coil spring 86
The urging means is constituted by this.

Note that the outward flange portion 80 of the sliding sleeve 82 that restricts the movement of the outer circumferential ring 66 toward the distal end side,
The head of the bolt 84 fixing the sliding sleeve 82 to the mold body 36 is always accommodated within the large diameter portion 72 of the through hole 74, as shown.

According to such a taper fitting mechanism, the outer circumferential ring 66 is always urged toward the fixed mold 22 by the urging force of the compression coil spring 86, and the mold 22,
As shown in FIG.
Of course, in the closed state of molds 2 and 24, as shown in FIG. Even when opening, both molds 2
The tapered surfaces 62 and 64 of the molds 2 and 24 are held in a fitted state, and the molds 22 and 24 are well aligned.

Therefore, in normal injection molding, in which the resin material is injected into the product cavity 38 while the molds 22 and 24 are kept closed, the injection molding process shown in FIGS. As shown, the molds 22 and 24 are slightly opened by the injection operation of the injection material 88 into the product cavity 38, and after the resin material 88 is injected, the movable mold 24 is pushed out to the mold closing position. Even in injection compression molding where a clamping operation is performed, as shown in FIG. 2, the molds 22 and 24 are opened by injecting resin material 88 into the product cavity 38. If the opening distance is set to be equal to or less than α, the mirror block 30 on the fixed side will remain open when the molds 22 and 24 are opened and closed, regardless of the existence of the sliding clearance between the movable platen 16 and the guide rod 20. At the peripheral edge of the mirror surface 26, the outer stamper holding member 4
Therefore, it is possible to avoid contact with the inner circumferential surface 58 of the mold 22 and 24 in a good manner, and therefore, the galling phenomenon does not occur due to contact between the molds 22 and 24 when they are opened and closed, as in conventional molds. can be effectively prevented.

Furthermore, if the mold according to this embodiment is used for injection compression molding, as shown in FIG. Since the injection operation can be performed and the clamping operation can be performed after the injection operation while maintaining the parallel state, the gap between the movable platen 16 and the guide rod 20 can be reduced as in the case of using a conventional mold. This prevents uneven thickness of the disk base due to the inclination of the movable mold 24 due to the sliding clearance of the disc base.
Therefore, the quality of the disk substrate can be significantly improved compared to before.

By the way, when a compact disk with a diameter of 120 mm is molded by injection compression molding using a conventional mold, the upper and lower ends of the compact disk (the parts corresponding to the upper and lower ends of the product cavity 38)
However, there was a thickness unevenness of about 20 μm.
In the molded product using the mold of this example,
It has been recognized that the difference is almost "0" and almost no thickness unevenness occurs.

Although one embodiment of the present invention has been described in detail above,
This is a literal illustration, and it goes without saying that the present invention should not be construed as being limited to this specific example.

For example, in the embodiment described above, the outer circumferential ring 66 as a taper forming member was provided on the movable mold 24 side, but such an outer circumferential ring 66 was provided on the movable mold 24 side.
It is also possible to provide it on the side.

Further, in the above embodiment, an example was described in which the present invention was applied to a mold in which the outer circumference of the product cavity 38 was defined by the outer stamper holding member 40. The present invention can also be applied to a mold in which the portion is defined by a cavity defining member provided on the fixed mold 22 side.

In addition, although not listed one by one, various modifications,
Things that can be implemented with modifications, improvements, etc. are:
It goes without saying.

[Brief explanation of drawings]

FIG. 1 is a sectional view of essential parts of a mold according to the present invention in a closed state. Figures 2 and 3 are
FIG. 2 is a sectional view corresponding to FIG. 1 showing mutually different operating modes when the mold shown in FIG. 1 is used for injection compression molding. FIG. 4 is an explanatory diagram schematically showing a conventional mold clamping device. 12: Fixed plate, 16: Movable plate, 20: Guide rod, 22: Fixed mold, 24: Movable mold, 26,
28: Mirror surface, 30, 32: Mirror block (cavity member), 34, 36: Mold body, 38: Product cavity, 40: Outer stamper holding member, 4
2: stamper, 62, 64: tapered surface, 66: outer circumferential ring (taper forming member), 68, 70: cylindrical surface, 82: sliding sleeve, 86: compression coil spring (biasing means).

Claims (1)

[Scope of Claims] 1. Includes a fixed mold and a movable mold in which a predetermined stamper is set by inner and outer stamper holding members, the mold being moved toward and away from the fixed mold, Tapers corresponding to each other provided on the outer periphery of the fixed mold and the movable mold form a disk base onto which the information of the stamper is transferred by injecting a predetermined resin material into a product cavity formed in the mold. In a disk base mold in which the molds are aligned by tapered fitting of surfaces, a taper forming member on the fixed mold side or the movable mold side having the tapered surface is attached to the fixed mold. The cavity member on the side or the movable mold side is provided so as to be movable in parallel by a predetermined distance in the direction of approach and separation of the molds, while urging the taper forming member in a direction to always protrude from the cavity member. Means is provided so that the tapered surfaces of the molds move the molds between the mold closing position of the mold and a position where the movable mold moves a predetermined distance in the mold opening direction from the mold mold closing position. A mold for a disk base, characterized in that it is held in a mated state for centering.