JPH07329125A - Mold for molding optical disc and molding of optical disc using mold - Google Patents

Abstract

PURPOSE:To enable stable continuous molding not generating the taking-out deficiency of a sprue especially coming into question. CONSTITUTION:A sprue bush 3 being an integrated product and having a straight cross section in a conventional mold is constituted of four parts connected through compression springs 3a in this mold and has a taper surface gradually becoming a small diameter toward a cavity. The sprue bush 3 before molding is held in an expanding direction by the action of the compression springs 3a and a resin guide passage is not formed. That is, the outer diameter of the sprue bush 3 has a taper shape gradually becoming a small diameter from a nozzle touch side to a cavity side and is divided into some parts in the longitudinal direction thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk molding die and an optical disk molding method using the same, and more specifically to an optical disk capable of stable continuous molding without sprue removal failure. The present invention relates to a mold for molding a substrate and a molding method using the mold.

[0002]

2. Description of the Related Art Generally, in a mold for molding an optical disk substrate, an injection hole portion for guiding resin into a cavity is formed as one independent member, that is, a sprue bush. The sprue bush is manufactured as an integrated product, and is inserted and held in a fixed mold located on the injection cylinder side of the molding machine.

A known document describing a conventional optical disk molding die is, for example, Japanese Patent Laid-Open No. 54-1627.
There is 54 publication. In this publication, a casting mold formed between a movable mold and a fixed mold and an injection communicating with the casting mold at the time of casting to enable automatic cutting of the runner during the molding process. It is provided with a gate means which constitutes a gate and is slidably provided, and a movement driving means which moves the gate means to cut the runner.

FIG. 6 is a block diagram of a conventional optical disk molding die. In the figure, 21 is a fixed mold body, 22 is a fixed mirror surface, and 2 is a fixed mirror surface.
3 is a sprue bush, 24 is a holding plate, 25 is a temperature control channel for sprue bushing, 26 is a fixed mold, 27 is a movable mold body, 28 is a movable mirror surface, 29 is an outer peripheral ring, 30 is a gate cut rod, 31 is hydraulic pressure. Cylinder, 32 is a movable mold, and 33 is an injection cylinder.

Molding of an optical disk substrate is generally performed in the following steps. As for the mold, the fixed mold 26 is mounted on the mold mounting plate located on the injection cylinder side of the injection molding machine, and the movable mold 32 is mounted on the mold mounting plate located on the mold clamping mechanism side. The stamper serving as a transfer master is attached to the cavity surface of a fixed or movable mold.

With such a structure, the mold mounting plate located on the mold clamping mechanism side, that is, the movable mold 32, moves and contacts the fixed mold 26 to form a molding cavity. Next, the injection cylinder 33 advances, the nozzle located at the tip contacts the sprue bush 23 having a resin injection hole, and resin is injected into the molding cavity. During the process in which the injected resin is cooled and solidified in the cavity, the unnecessary gate portion including the sprue is cut from the optical disk substrate, which is a product, by the gate cutting mechanism 30 in the movable mold.

After that, when the movable mold 32 leaves the fixed mold 26 while holding the optical disk substrate and the gate portion (hereinafter, simply sprue) including unnecessary sprues, the optical disk substrate reaches a predetermined position. Take out the sprue from the mold and complete one step. Such a series of steps has already been automated and does not require operator intervention.

[0008]

However, in the series of automated steps in the conventional mold for optical disk molding, the obstacle is an unsuccessful removal of the optical disk substrate and the sprue. The cause is that one or both of the optical disc substrate and the sprue, which are originally to be restrained and held by the movable mold, also receive the restraining force from the fixed mold, and depending on the magnitude relation of the restraining forces, either one or both of them are restrained. This is a defect that remains in the fixed mold. In particular, since the projected area of the sprue in the mold is small, the binding force on the movable die side is relatively small, and the sprue is relatively weak against the binding force (disturbance) on the fixed die side.

The restraining force received from the fixed side means a minute cured resin of leak resin generated in the resin injection hole portion (nozzle touch side) of the sprue bush, which is an integral product, and scratches on the portion.
Or, due to scratches in the resin guideway in the sprue bush and pure frame release resistance (demolding failure) from the same part,
When these restraint forces exceed the restraint forces on the movable side, the sprue remains in the sprue bush on the fixed mold side.

If a strong undercut portion or the like is formed in order to strengthen the restraining force on the movable side, dust will be generated when the movable die is taken out from the mold side, resulting in deterioration of the substrate quality. Will end up. This kind of ejection failure
The mold temperature, which had been strictly controlled until then, was changed, and the time and material loss associated with preforming until it became stable again reached a level that cannot be ignored.

The present invention has been made in view of the above circumstances, and in order to solve the problem of sprue take-out failure which is particularly problematic, that is, the sprue fixed die residue, stable continuous operation without occurrence of pick-up failure An object of the present invention is to provide a mold for molding an optical disk and a method for molding an optical disk using the mold.

[0012]

In order to achieve the above object, the present invention provides (1) a fixed mold having a sprue bush having a resin injection hole at its center, and a fixed mold facing each other. And is attached to either one of the molds by a movable mold which is disposed so as to be able to come into contact with and separate from the fixed mold and forms a molding cavity with the fixed mold. In an optical disc molding die for molding a duplicate substrate of an optical disc by transferring a relief pattern from a stamper arranged in a cavity, the sprue bush outer diameter is
It has a taper shape in which the diameter gradually decreases from the nozzle touch side toward the cavity side, and is divided into several parts in the longitudinal direction, and further, (2) the connecting portion of each component constituting the sprue bush has Each part has an elastic member acting in a direction to expand with respect to the central axis,
Further, (3) in the fixed mold, a fitting hole of a member that fits with the sprue bush has a tapered shape in which a diameter becomes smaller from a nozzle touch side toward a cavity side,
In addition, the slope of the taper is substantially equal to the slope of the fitting surface of the sprue bush, and (4) the sprue bush slidably fitted in the fixed mold can slide. Or in the optical disc molding method using the optical disc molding die according to (5) claim 1, 2, 3 or 4, the nozzle touch pressure at the time of injection is expanded and held. The pressure is set to a value sufficient for the sprue bushes to be in close contact with each other, or (6) in the optical disc molding method using the optical disc molding die according to claim 1, 2, 3 or 4, It is characterized in that the gate cut pressure for separating the gate portion is set to a pressure sufficient for separating and enlarging the sprue bush integrally integrated.

[0013]

The optical disk molding die of the present invention having the above-described structure is provided with a fixed mold having a sprue bush having a resin injection hole at the center, and a fixed mold facing the fixed mold. A movable die which is disposed so as to be able to come into contact with and separate from the fixed die, and is attached to either one of the molds by a movable die which forms a molding cavity between the fixed die and the movable die. A die for molding a duplicate substrate of an optical disc by transferring a relief pattern from a stamper. (1) The sprue bush has a taper shape in which the outer diameter gradually decreases from the nozzle touch side to the cavity side, and the length is long. Is divided into a number of directions,
An elastic member that acts in a direction in which each component expands with respect to a central axis is provided at a coupling portion of each component that forms the sprue bush, and in the fixed mold, a member that fits with the sprue bush is fitted. The hole has a taper shape that becomes smaller in diameter from the nozzle touch side toward the cavity side, and its slope is almost the same as the slope of the mating surface of the sprue bush, so the sprue bush is divided except when resin is injected. Since it is held in the fixed mold, the sprue bushing does not generate any restraining force on the sprue on the fixed mold side, and the sprue bushing can stably hold and hold the movable mold side. (2) Since the fixed mold has a sprue bush sliding mechanism capable of slidingly moving the sprue bush fitted in a slidable manner, even if the above molding conditions cannot be adopted to ensure substrate quality, The sprue bush can be divided or integrated. (3) In the optical disc molding method using the optical disc molding dies of (1) and (2), the pressure that is sufficient for the sprue bushes that hold the nozzle touch pressure at the time of injection to be closely adhered and integrated. The sprue bushing that has been set and the gate cut pressure that separates the gate from the molded product is set to a pressure sufficient to separate and expand the sprue bushing, so the sprue bushing can be divided or integrated. Is performed in the normal molding process operation, and the sprue bush can be operated without using special control means.

[0014]

Embodiments will be described below with reference to the drawings. FIG. 1 is a block diagram for explaining an embodiment of an optical disk molding die according to the present invention. In the figure, 1 is a fixed mold body, 2 is a fixed mirror surface, 3 is a sprue bush, 3a is a compression spring, and 4 is a compression spring. Is a holding plate, 5 is a thrust bearing, 6 is a temperature control channel for sprue bushing, 7 is a fixed mold, 8 is a movable mold body, 9 is a movable mirror surface, 10 is an outer ring, 11 is a gate cut rod, and 12 is a hydraulic cylinder. , 13 are movable dies, and 14 is an injection cylinder.

The state shown in the figure shows before molding, and shows the state in which the movable mold 13 is separated from the fixed mold 7. The sprue bushing 3, which is a single piece and has a straight cross section in the conventional mold, is composed of four parts coupled through the compression spring 3a in the mold of the present invention, and the cross section faces the cavity side. The taper cross section has a gradually decreasing diameter. By the action of the compression spring 3a, the sprue bush 3 before molding is held in the expansion direction, and the resin guide path is not formed.

2 (a) to 2 (d) are views showing a tapered cross section of the sprue bush, FIG. 2 (a) is a sprue bush except when resin is injected, and FIG. 2 (b) is an arrow AA in FIG. View,
Figure (c) is a sprue bush at the time of resin injection, and Figure (d) is a view taken along the line BB of Figure (c). Figure (b) and Figure (d)
In, the sprue bush has a tapered cross section whose diameter gradually decreases toward the lower side in the figure.

FIG. 3 shows the resin injection state from the state of FIG.
It is a figure showing the time when it became what is called a state during molding. Reference numerals in the figure are the same as those in FIG. The sprue bush 3 which had been separated and enlarged until then is pushed toward the cavity side by the pressure of the injection cylinder 14 coming into contact for injection, and the sprue bush 3 is closely integrated due to the action of the tapered cross section of the fixed mold insertion hole, and is shown by a broken line in the drawing. The original resin guideway of the sprue bush is formed. In this state, conventional injection (injection) is performed.

FIG. 4 is a view showing a state in which molding is further progressed from the state of FIG. 3 and a sprue portion unnecessary for a product is cut. Reference numerals in the figure are the same as those in FIG. To cut the sprue, the gate cut rod 11 advances into the cavity by the pressure of the hydraulic cylinder 12, and separates the sprue portion from the optical disk substrate that is a product. At this time,
The sprue bush 3 receives the pressure of the hydraulic cylinder 12 via the injected and solidified resin and the gate cut rod 11.

As a result, the sprue bush 3 retracts to the injection cylinder 14 and, at the same time, is separated and expanded by the action of the built-in compression spring. At this point, the sprue is released from the sprue bush, in other words, various restraining forces received from the fixed mold, and thereafter, the undercut portion (not shown) provided on the gate cut rod 11 of the movable mold is released. ) Will be governed only by the binding force.

FIG. 5 is a diagram showing a process of taking out a product at the final stage of the molding process. Reference numerals in the figure are the same as those in FIG. The molded substrate 15 is held on the movable mold side by the sliding resistance with the outer peripheral ring 10, and the sprue 16 is also held on the movable mold side by the restraining force of the undercut portion. After that, the molding substrate 15 and the sprue 16 are taken out of the movable mold, and a series of molding steps are completed (return to the state of FIG. 1).

When performing continuous molding while the injection cylinder is in contact with the mold, or when molding is performed in a setting in which the contact pressure of the injection cylinder and the pressure at the time of gate cutting oppose each other, the fixed mold is used. A drive device for sliding the sprue bush is provided in the main body, and the sprue bush is slid in synchronization with the time of gate cutting or the time of moving the movable mold (mold opening) to perform the above operation.

[0022]

As is apparent from the above description, the present invention has the following effects. (1) Effects corresponding to claims 1, 2 and 3: a fixed mold having a sprue bush having a resin injection hole at its center, and a facing mold facing the fixed mold and contacting with and separating from the fixed mold. From a stamper that is operably arranged and is mounted on one of the molds by a movable mold that forms a molding cavity with the fixed mold and that is disposed in the molding cavity. A mold for transferring a relief pattern to mold a duplicate substrate of an optical disc. The sprue bush has a tapered outer diameter that gradually decreases from the nozzle touch side toward the cavity side, and is divided into several parts in the longitudinal direction. In the fixed mold, the sprue bushing is provided with an elastic member that acts in a direction in which each component expands with respect to a central axis, at a coupling portion of each component that constitutes the sprue bush. Fitting hole parts to be fitted with the,
It has a taper shape that becomes smaller in diameter from the nozzle touch side toward the cavity side, and its slope is almost the same as the slope of the mating surface of the sprue bush, so the sprue bush is divided except when resin is injected and the fixed metal Since it is held in the mold, there is no restraint force on the sprue on the fixed mold side due to the sprue bush, and it is stable and stable.
It can be restrained and held on the movable mold side. (2) Effect corresponding to claim 4: Since the fixed mold has a sprue bush sliding mechanism capable of slidingly moving the sprue bush fitted slidably,
In order to secure the substrate quality, the sprue bush can be divided or integrated even if the above molding conditions cannot be adopted. (3) Effects corresponding to claims 5 and 6: (1),
In the optical disc molding method using the optical disc molding die of (2), the pressure of the nozzle touch at the time of injection is set to a sufficient pressure so that the held sprue bushes are closely adhered and integrated. Since the gate cut pressure for separating the gate part from is set to a pressure sufficient to separate and expand the sprue bush which is closely integrated, splitting or unifying the sprue bush in the normal molding process operation Performed, the sprue bush can be operated without the use of special control means.

[Brief description of drawings]

FIG. 1 is a state diagram (No. 1) for explaining an embodiment of an optical disk molding die according to the present invention.

FIG. 2 is a diagram showing a sprue bush in the present invention.

FIG. 3 is a state diagram (part 2) of the optical disk molding die according to the present invention.

FIG. 4 is a state diagram (part 3) of the optical disk molding die according to the present invention.

FIG. 5 is a state diagram (part 4) of the optical disk molding die according to the present invention.

FIG. 6 is a configuration diagram of a conventional optical disk molding die.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fixed type main body, 2 ... Fixed mirror surface, 3 ... Sprue bushing, 3a ... Compression spring, 4 ... Holding plate, 5 ... Thrust bearing, 6 ... Temperature control channel for sprue bushing, 7 ... Fixed mold, 8 ... Movable type Main body, 9 ... Movable mirror surface, 10 ... Outer ring, 11 ... Gate cut rod, 12 ... Hydraulic cylinder, 13 ... Movable mold, 14 ... Injection cylinder, 15 ... Molded substrate, 16 ... Sprue.

Claims (6)

[Claims] 1. A fixed mold having a sprue bush having a resin injection hole at its center, and a fixed mold facing each other,
Inside the molding cavity, the fixed mold is attached to either one of the molds by a movable mold that is arranged so as to be able to come into contact with and separate from the fixed mold and forms a molding cavity with the fixed mold. In a mold for optical disc molding for transferring a relief pattern from a stamper arranged on a substrate to mold a duplicate substrate of an optical disc, the sprue bush has a taper shape in which the outer diameter gradually decreases from the nozzle touch side toward the cavity side. , And an optical disk molding die, which is divided into several parts in the longitudinal direction. 2. The optical disk molding according to claim 1, wherein an elastic member that acts in a direction in which each of the components that constitutes the sprue bush expands with respect to a central axis is provided at a coupling portion of the components. Mold. 3. In the fixed mold, a fitting hole of a member fitted with the sprue bush has a taper shape in which a diameter becomes smaller from a nozzle touch side toward a cavity side,
The optical disk molding die according to claim 1, wherein the taper has a slope substantially equal to a slope of the fitting surface of the sprue bush. 4. The mold for optical disk molding according to claim 1, wherein the fixed mold has a sprue bush sliding mechanism that allows the sprue bush fitted slidably to slide. . 5. The optical disk molding method using the optical disk molding die according to claim 1, 2, 3 or 4, which is sufficient for the sprue bushes that hold the nozzle touch pressure at the time of injection to be closely integrated. An optical disk molding method characterized in that the pressure is set. 6. An optical disk molding method using the optical disk molding die according to claim 1, 2, 3 or 4, wherein a sprue bush integrally integrated with a gate cutting pressure for separating a gate portion from a molded product is separated and enlarged. An optical disk molding method, characterized in that the pressure is set to a level sufficient to make the optical disk.