JP3161266B2 - Injection compression mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection compression molding die for molding an optical disk such as a mini disk which is a disk-shaped optical record carrier.

[0002]

2. Description of the Related Art In an optical disk such as a mini disk, a stamper as an original recording information is disposed in a cavity formed between a fixed mold and a movable mold, and a molten resin is injected and filled and cured. It is generally manufactured by The objective is to improve the transfer rate of information to the optical disk formed from the stamper, to reduce the birefringence, to equalize the pressure difference between the inner and outer circumferences in the radial direction, and to compensate for the amount of shrinkage during cooling. There has been proposed an injection compression molding method for forcibly pressing a resin filled in a cavity.

[0003] As a mold for an optical disk employed in the injection compression molding method, a mold having one cavity for molding an optical disk between a fixed mold and a movable mold is generally used. The movable mold is provided with a core mold constituting a part of the inner surface of the cavity so as to be movable in the mold clamping direction. By pressing the core mold toward the cavity, the volume of the cavity is reduced, and the resin in the cavity is compressed.

In this case, the pressurizing means for pressing the core mold toward the cavity is constituted by, for example, a hydraulic cylinder, and is provided in an injection molding machine to which the optical disc mold is mounted. Then, in the injection molding machine, a pressing force for pressing the core mold is generated using a hydraulic pressure for performing mold clamping.

[0005]

By the way, in such an optical disk mold, a plurality of cavities for molding an optical disk are provided in one mold in order to improve production efficiency. It is conceivable to perform multi-cavity. In this case, a movable mold having a plurality of core molds capable of changing the volume of each cavity is provided.

However, if such an optical disk mold is used, the injection molding machine must be equipped with a plurality of hydraulic cylinders for pressing a plurality of core dies. In addition to the large size, the conventional equipment, that is, a general-purpose injection molding machine, cannot be effectively used, and there is a disadvantage that a new dedicated optical disc machine must be introduced.

Further, as a hydraulic cylinder for performing injection compression molding, a hydraulic cylinder having a large sectional area capable of generating a considerable pressure is required. Therefore, in the case of performing multi-cavity, it is conceivable that the space between the cavities becomes large, and the size of the mold becomes large, the runner length for supplying the resin to each cavity increases, and the like.

When the size of the mold is increased, the thickness of the mold must be increased in order to maintain the rigidity of the mold, which may increase the weight. When the length of the runner is increased, a heating means for keeping the molten resin flowing in the runner in a molten state must be provided over a wide range, and a more complicated structure and Inconvenience is considered.

Further, when all the hydraulic cylinders are simultaneously operated by utilizing the hydraulic pressure of the injection molding machine, the following disadvantages can be considered. That is, since the thickness of the stamper disposed in the cavity varies according to the amount of information and the like held therein, when changing the core mold by the same amount of movement at the same pressure, It is difficult to optimize all the molding conditions in each cavity. Therefore, it is desired that the molding conditions are finely adjusted and balanced for each cavity to improve the quality of products in all cavities.

The present invention has been made in view of the above-mentioned circumstances, and aims at improving rigidity and thus product accuracy by constructing a compact mold, and in addition, simplifying the structure of an injection molding machine. It is an object of the present invention to provide an injection compression molding die that can adopt a general-purpose machine.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention comprises a fixed mold and a movable mold which are brought into contact with and separated from each other to form a plurality of cavities at the time of mold clamping. In addition, a core mold that constitutes a part of the inner surface of each cavity and is disposed so as to be movable in the mold clamping direction, and a pressing unit that presses the core mold toward the cavity is provided for each cavity. There has been proposed an injection compression molding die in which the pressurizing means includes a plurality of cylinders arranged in series.

In the above-mentioned injection compression molding die, it is effective if the pressing means is connected to control means for individually operating each pressing means based on a mold clamping completion signal.

[0013]

According to the injection compression molding die of the present invention, the movable die is brought into close contact with the fixed die, so that a plurality of cavities are formed between the two dies. When the pressurizing means is operated while the cavity is filled with the molten resin, the core mold forming a part of the inner surface of the cavity is pressed so as to reduce the volume of the cavity, and the inside of the cavity is pressed. Will be compressed. As a result, the pressure difference between the moldings formed in the cavity is made uniform. For example, when the molded body is an optical disk, the pressure difference generated between the inner and outer circumferences is made uniform in the radial direction, so that the product accuracy is improved, the transfer rate of information from the stamper is improved, and at the same time, the pressure difference is reduced. A high-quality birefringent optical disk is formed.

In this case, since the pressurizing means for pressing the core mold is provided on the movable mold, the injection molding machine to which the injection compression molding mold is attached is operated with respect to the pressurizing means of the mold. It is possible to adopt a general-purpose machine for supplying a fluid. In addition, since the pressurizing means is configured by arranging a plurality of stages of cylinders in series, the generated pressing force is distributed to each stage, so that the diameter of the entire pressurizing means is reduced, and the dimension between the cavities is reduced. And the mold can be made small and highly rigid. As a result, the quality of the molded article as a product can be further improved.

In the above-mentioned injection compression molding die, if the pressurizing means is connected to a control means for individually operating each pressurizing means based on a mold-clamping completion signal, the control is issued from the injection molding machine. The compacts in each cavity are individually compressed at the optimal timing and pressure based on the mold-clamping completion signal, and the molding conditions in all cavities can be adjusted optimally. Thereby, the quality of all the molded bodies molded in the plurality of cavities is improved.

[0016]

FIG. 1 shows an embodiment of an injection compression molding die (hereinafter simply referred to as a molding die) according to the present invention.
3 will be described with reference to FIG. The molding die 1 according to the present embodiment is an injection compression molding die for an optical disk, and as shown in FIG. 1, is attached to an injection molding machine (not shown), and is connected to each other by the operation of the injection molding machine. Fixed mold 2 to be released
And a movable mold 3. Between the fixed mold 2 and the movable mold 3, a cavity 4 for molding a plurality of (for example, four) optical discs (molded bodies) in a clamped state is formed.

The fixed mold 2 is a mold fixed to a fixed side mounting plate (not shown) of an injection molding machine, and includes a plurality of nozzles 5 for injecting a molten resin into each cavity 4,
And a manifold 7 for distributing the molten resin supplied from the injection molding machine to each nozzle 5 via the runner 6.

The fixed mold 2 has a ring-shaped stamper retainer 9a for fixing the outer periphery of the stamper 8 to a surface which forms one inner surface of each cavity 4, and a support sleeve 9b for fixing the inner periphery of the stamper 8. And are attached.
The stamper holder 9a and the support sleeve 9b allow the stamper 8 to move the surface on which the information is imprinted into the cavity 4
Each cavity 4 can be attached inward. The lower surface of the fixed mold 2 constitutes the upper inner surface of the cavity 4.

The movable mold 3 is a mold fixed to a movable mounting plate (not shown) of the injection molding machine, and includes a plurality of core molds 10 movably provided in a mold opening direction. Pressurizing means 11 capable of independently displacing molds 10
And a control means 12 connected to the pressurizing means 11 for receiving a signal from the injection molding machine and supplying an appropriate hydraulic pressure to each pressurizing means 11, and a sleeve 13 of the fixed mold 2. Cut mechanism 14 for pushing and cutting the gate from below and an ejector mechanism 15 for pushing the sprue
And the like. In FIG. 1, reference numeral 14a is a gate cut sleeve, 14b is a cylinder, 15a is an ejector pin, 15b is a pressing rod, 15c is a spring, and 19 is disposed around the core mold 10 to support the movement of the core mold 10. And a cavity ring forming an inner peripheral surface of the cavity 4.

The core mold 10 is, for example, fixed to the inside of the movable mold 3 and arranged in a fitted state in a sliding sleeve 17 having a plurality of steel balls 16 arranged on an inner peripheral surface thereof. By this operation, the steel ball 16 can be slightly displaced in the vertical direction while rolling on the outer peripheral surface thereof. As shown in FIG. 1, the pressurizing means 11 is composed of a plurality of (for example, two) hydraulic cylinders (cylinders) 18.

The hydraulic cylinders 18 are mounted in series with each other, and generate a pressing force simultaneously in the same direction by the hydraulic pressure supplied from the control means 12. That is, each hydraulic cylinder 18 is configured to distribute the pressure receiving area of the piston 18a for generating the required pressing force according to the number of stages of the hydraulic cylinder 18. As a result, the outer diameter of each hydraulic cylinder 18 is formed to be slightly larger than the outer diameter of the cavity 4 for molding the optical disk, and the mutual interval of the plurality of cavities 4 is reduced. Is possible.

The control means 12 is provided, for example, as shown in FIG.
As shown in the figure, a timer 12a operated based on a signal transmitted from the injection molding machine, and the timer 12a
And a hydraulic adjustment unit 12b that adjusts the hydraulic pressure supplied to the hydraulic cylinder 18 in accordance with the drive signal from the
, Ie, for each cavity 4.
The timer 12a transmits a signal to the hydraulic pressure adjusting unit 12b so as to generate a hydraulic pressure after a set time delay from receiving the mold completion signal of the injection molding machine. Further, the timing of the pressure increase to the hydraulic cylinder 18 during the injection of the resin is also instructed to the hydraulic adjustment unit 12b.

One timer 12 in the control means 12
FIG. 3 is a time chart showing the operation status of the hydraulic pressure adjustment unit 12b. According to this time chart, when the mold closing completion signal (second mold closing) is transmitted from the injection molding machine, the core mold 10 is first operated by the operation of the timer 12a (one-pressure delay timer). A signal (1 pressure) to the hydraulic pressure adjustment unit 12b is transmitted after a preset time has elapsed.

When this one-pressure signal is transmitted, the hydraulic cylinder 18 (core compression cylinder) is operated, and the resin filled in the cavity 4 is compressed. Next, every time a predetermined time set in the timer 12a elapses, the two pressures, three pressures,
Pressure..., Up to six pressure signals are transmitted to the pressure adjusting unit 12b,
The hydraulic pressure supplied to the hydraulic cylinder 18 is increased. Then, prior to the start of the mold opening operation of the injection mold (the mold opening start), the core mold 1 to the hydraulic cylinder 18 is transmitted to the hydraulic cylinder 18 by a mold opening signal (not shown) transmitted from the injection molding machine.
The hydraulic pressure supplied in the zero protruding direction is changed to a very weak pressure such that the core mold 10 does not retreat. Thereafter, the hydraulic pressure for operating the core mold 10 in the return direction is supplied to the hydraulic cylinder 18 simultaneously with the end of the product ejector pin protrusion time (not shown).

In the molding die 1 according to the present embodiment, since the timer 12a and the hydraulic pressure adjusting unit 12b operated as described above are provided for each cavity 4,
Each core mold 1 for compressing the resin in each cavity 4
It is possible to individually set the operation timing of 0. Therefore, for example, the quality of the molded product may differ depending on the molding conditions for each cavity 1 such as when the thickness of the stamper 8 differs for each cavity 4. The operation timing of the core mold 10 for compressing the resin in each cavity 4 can be adjusted to an optimum state according to the workmanship.

As a result, the optical disc as a molded product molded in all the cavities 4 can be made uniform and of high quality. Further, according to the molding die 1 according to the present embodiment, the pressing means 11 for pressing each core die 10 is provided in the molding die 1 attached to the injection molding machine.
Control means 12 for individually operating the pressurizing means 11 are provided. Therefore, any injection molding machine may be used as long as it can transmit several types of signals such as a mold closing / mold opening completion signal and a hydraulic pressure to the molding die 1, and even if a special injection molding machine is developed or modified. Instead, the present invention can be applied to a general-purpose injection molding machine that has been conventionally used, and an optical disc can be molded by multi-cavity molding.

According to the molding die 1 of the present embodiment, the pressing means 11 for pressing the core die 10 is constituted by connecting a plurality of hydraulic cylinders 18 in series. Thus, the dimension between the cavities 4 can be reduced by reducing the outer diameter dimension. Therefore,
The length of the runner 6 provided on the fixed mold 2 can be reduced, and the number of heating members such as heaters for holding the runner 6 in a heated state can be reduced to simplify the mold structure. Besides, it is possible to prevent the weight of the entire molding die 1 from increasing and to maintain the rigidity of the molding die 1 by a compact design to improve the product accuracy.

In this embodiment, the four-piece molding die 1 is described. However, the present invention is not limited to this, and it is applicable to two, three, five or more molding dies 1. It may be. Further, the pressure means 11 is exemplified by one in which two hydraulic cylinders 18 are connected in series, but instead of this, if, for example, three, four,. In addition to this, it is also possible to increase the pressing force. In this case, the dimension increases in the mold opening direction, so that the design may be appropriately made while considering the balance between the two.

Further, the molding die 1 according to the present invention includes a pressing means 11 for pressing the core die 10 and a control means 12 for adjusting the operation timing of the pressing means 11. Therefore, other configurations such as the structure of the fixed mold 2 and the movable mold 3, the structure of the ejector mechanism 15, the structure of the gate cut mechanism 14,
The support structure and the like of the core mold 10 may be arbitrarily changed. In addition, although an injection compression molding die for molding an optical disk has been described as an example, the present invention may be applied to molding any other molded body instead.

[0030]

As described above in detail, the injection compression molding die according to the present invention is movable toward and away from the fixed die to form a plurality of cavities between the fixed die and the mold during clamping. In the mold, for each cavity, pressurizing means is provided for pressing a core mold, which constitutes a part of the inner surface thereof and is movably arranged in the mold clamping direction, toward the cavity, and the pressurizing means is arranged in a plurality of stages in series. Since it is constituted by cylinders arranged, the pressing force of the core mold on each cavity can be adjusted individually, and even in the case of multi-cavity, each cavity is brought close to make the mold itself compact. The effect that it can comprise is produced.

As a result, it is possible to improve the product accuracy of the molded body without reducing the rigidity of the mold, and to eliminate the difference generated for each cavity by individually adjusting the pressing force of the core mold. That is, since a plurality of molded products obtained by one injection compression molding can be molded uniformly and with high quality, production efficiency can be significantly improved.

Furthermore, if the pressurizing means is connected to control means for individually operating each pressurizing means based on the mold-clamping completion signal, general-purpose injection molding which has been conventionally used or has no special specifications. The present invention has an effect that the molding can be performed at a high production efficiency by applying to a molding machine. Therefore, investment in new equipment such as introduction of a special injection molding machine or new design can be reduced as much as possible, and product cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of an injection compression molding die according to the present invention.

FIG. 2 is a block diagram showing a control unit connected to a pressurizing unit of the injection compression molding die of FIG.

FIG. 3 is a time chart showing operation timings of the injection compression molding die of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molding die (injection compression molding die) 2 Fixed die 3 Movable die 4 Cavity 10 Core die 11 Pressurizing means 12 Control means 18 Hydraulic cylinder (cylinder)

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-220598 (JP, A) JP-A-61-125824 (JP, A) JP-A-6-208734 (JP, A) 254916 (JP, A) JP-A-61-188122 (JP, A) JP-A-61-229520 (JP, A) JP-A-5-169512 (JP, A) Full-scale application Showa 56-18200 (JP, U) Japanese Utility Model Application Showa 49-39871 (JP, U) Japanese Utility Model Application Hei 3-39530 (JP, U) Registered utility model 3011097 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 45 / 00-45/84

Claims (2)

(57) [Claims] 1. A fixed mold and a movable mold which are mutually contacted and separated to form a plurality of cavities at the time of mold clamping. The movable mold forms a part of an inner surface of each cavity and is formed in a mold clamping direction. A movable core mold and a pressurizing means for pressing the core mold toward the cavity are provided for each cavity, and the pressurizing means includes a plurality of cylinders arranged in series. An injection compression molding die, comprising: 2. The injection compression molding die according to claim 1, wherein said pressurizing means is connected to control means for individually operating each pressurizing means based on a mold completion signal.