JPH03268918A - Mold for molding of disc - Google Patents

Abstract

PURPOSE:To contrive simplification of blanking of an inner circumference of a disc by moving smooth a sprue bushing, by holding movably the sprue bushing by a ball guide. CONSTITUTION:A ball guide 24 supporting turnably a ball 23 in a ball supporting hole 22 bored into a plate 21 is provided in a large-diameter part 5a of a through hole 5 provided in the central part of a stationary mold 1 and a large-diameter part 6a of a sprue bushing 6 is supported movably in an axial direction. Then molten resin through a molten resin casting part is cast into a cavity 4 through a hot runner 8 and gate 9. In this instance, though the sprue bushing 6 is heated by the molten resin and thermal expansion is performed, since the same is supported movably by a ball guide 24, the same is movable smoothly. Therefore, when a punch 13 is moved forward, the sprue bushing 6 is moved backward smoothly, blanking of an inner circumference of a disc 3 can be performed and impossibility of a movement of the sprue bushing which is caused by conventional galling can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a disk molding mold for molding a disk such as an optical disk.

(Prior Art) A mold for molding an optical disc has conventionally been constructed as shown in FIG. That is, 1 is fixed type, 2
is movable. Template plate of fixed mold 1] A cavity 4 for molding a disk 3 is provided at the joint portion of template a of fixed mold 1 and template plate 2a of movable mold 2. A through hole 5 is bored in the center of the fixed mold 1. This through hole 5 is formed by a step hole having a large diameter portion 5a, a medium diameter portion 5b, and a small diameter portion 5c from the outside to the inside.
A spool bushing 6 consisting of a stepped shaft having a medium diameter portion 6b and a small diameter portion 6C is inserted into the cavity 4 so as to be freely movable forward and backward. A hot runner 8 communicating with the molten resin injection part 7 is provided at a sixth portion of the spool bush 6, and this hot runner 8 communicates with the cavity 4 via a gate 9.

On the other hand, the movable mold 2 is provided with a through hole 10 opposite to the through hole 5. This through hole 10 is formed by a step hole having a large diameter portion 10a and a small diameter portion 10b from the outside to the inside. A punch 13 pressed by a punch driving section 12 is inserted into the cavity 4 so as to be freely movable forward and backward. An ejector pin 14 is inserted into the center of the punch 13 so as to be able to move forward and backward relatively, and a cylindrical pin 14 is inserted between the outer peripheral surface of the punch 13 and the inner peripheral surface of the through hole 10, as shown in FIG. A shaped stamper support member 15 is interposed so as to be movable forward and backward. The inner periphery of the stamper 16 located inside the cavity 4 is supported at the tip of the stamper support member 15. Note that 18 is an O-ring that seals between the stamper support member 15 and the through hole 10, and is formed to prevent air from leaking during mold release.

Furthermore, as shown in FIG. 9, the tip of the stamper support member 15 is formed into a cylindrical support part 19, and one support part is inserted into the circular holes 1 and 6a of the stamper 16 to support it. However, the support part 19 and the circular hole 1 of the stamper] 6.
6a, there is a clearance g of several tens of micrometers, and positioning is performed such that this clearance g is constant over the entire circumference of one support part.

(Problems to be Solved by the Invention) By the way, the conventional disk molding mold configured as described above has various problems as described below.

a. Before the molten resin injected into cavity 4 solidifies,
The punch 13 is moved forward and the spool bushing 6 is moved backward to punch the inner circumference of the disk 3. However, since the spool bushing 6 is provided with a hot runner 8, the spool bushing 6 thermally expands. Galling occurs between the spool bush 6 and the inner peripheral surface of the through hole 5, and the spool bush 6 may not move smoothly or become immovable, making it impossible to punch out the inner periphery of the disk 3.

b. The stamper 16 is supported by inserting the circular hole 16a into the cylindrical support part 19 of the stamper support member 15, but there is a clearance of several tens of μm between the support part 19 and the circular hole 16a of the stamper 16. g, the stamper 16 is lowered by the clearance of 2 due to its own weight.

Therefore, due to the displacement of the stamper 16, the recording on the disk 3 will also be displaced, resulting in defective molding.

C. Although the space between the stamper support member 15 and the through hole 10 is sealed with an O-ring 18 to prevent air from leaking during mold release, it becomes difficult to attach and detach the stamper support member 15, and it is difficult to attach and detach it by force. This may cause the O-ring 18 to come off or be damaged, and there is a risk that air may leak during mold release. In addition, the stamper support member 15
In order to facilitate the attachment and detachment of the movable die 2 and to prevent leakage, high precision is required in machining the through hole 10 of the movable mold 2, which is difficult to manufacture and causes an increase in cost.

This invention was made in view of the above-mentioned circumstances, and its purpose is to allow the spool bush to move smoothly and to facilitate punching of the inner periphery of the disc.
To provide a disk molding die which can prevent displacement of a stamper, prevent air from leaking between a stamper support member and a through hole during demolding, and allow easy demolding by air pressure.

[Structure of the Invention (Means and Effects for Solving the Problem) In order to achieve the above object, claim 1 provides a cavity for molding a disk between a fixed mold and a movable mold. At the same time, a spool bushing having a gate communicating with the hot runner is provided on the fixed mold so as to be able to move forward and backward with respect to the cavity, and a spool bushing that faces the spool bushing and that is movable back and forth with respect to the cavity is provided on the movable mold. In a disk molding die, a freely movable punch is provided, and the punch is moved forward and the spool bush is retreated to punch out the inner circumference of the disc.The spool bush is movably supported by a ball guide. There is a particular thing.

When the punch moves forward when punching the inner periphery of the disk, the spool bushing is guided by the ball guide and smoothly retreats, punching out the inner periphery of the disk.

According to a second aspect of the present invention, a stamper support member is provided in the movable mold to project into the interior of the cavity and support a circular hole in the stamper, and a clearance is provided between the circular hole in the stamper and the stamper support member, and a clearance is provided between the circular hole in the stamper and the stamper support member. This is because the circular hole is eccentrically downward.

When the circular hole of the stamper is fitted into the stamper support member, the stamper is positioned at a predetermined position by sliding downward by the amount of clearance due to the stamper's own weight.

According to a third aspect of the present invention, a through hole is provided in the movable mold, the stamper support member is inserted into the through hole, and a thin film is provided on the stamper support member to be brought into close contact with the through hole by air pressure during mold release. be.

According to a fourth aspect of the present invention, the thin film is brought into close contact with the inner circumferential surface of the through hole due to air pressure during mold release, thereby causing air leakage. An outer peripheral tapered surface is provided on the outer periphery of the rear end of the stamper support member,
A nest having an inner tapered surface that joins the outer tapered surface is inserted between the outer tapered surface and the inner circumferential surface of the through hole, and the nest is pressed in the insertion direction by a spring.

The nest is inserted between the outer peripheral tapered surface and the inner peripheral surface of the through hole by the biasing force of the spring, and the wedge action prevents air leakage.

(Embodiments) Hereinafter, each embodiment of the present invention will be described based on the drawings, or the same components as in the conventional art will be given the same numbers and the explanation will be omitted.

1 and 2 show a first embodiment, in which a large through hole 5 (I part 5 a
A ball support hole 22 bored in the plate 21...
A ball guide 24 rotatably supporting balls 23 is provided at the spool bushing 6, and the large diameter portion 6a of the spool bushing 6 is supported by the ball guide 24 so as to be movable in the axial direction.

According to the disk molding die configured as described above, when molten resin is injected from the molten resin injection part 7, the molten resin is injected into the cavity 4 via the hot runner 8 and the gate 9. At this time, the spool bushing 6 is heated by the molten resin and thermally expands, but since it is supported by the ball guide 24 of the spool bushing 6 so as to be freely forward and backward, it can be smoothly moved. Punch 1
When the spool bushing 3 moves forward, the spool bushing 6 moves back smoothly and the inner periphery of the disc 3 can be punched out, thereby eliminating the conventional inability to move the spool bushing due to galling.

FIG. 3 shows a second embodiment, in which a stamper 25 set in the cavity 4 is disk-shaped, and a circular hole 26 having a keyway 26a is provided in the center thereof. The circular hole 26 is formed in the support portion 1 of the stamper support member 15.
9 and the stamper 25 for 2 minutes (for example, 20 μ
m) and is eccentrically provided downward.

Therefore, when the circular hole 26 of the stamper 25 is fitted into the support part 19 of the stamper support member 15 and the key 19a is engaged and supported in the keyway 26a, the stamper 25 is shifted downward by the clearance 2 due to its own weight, and the The upward circumferential surface of the hole 26 comes into contact with the support part ]9, and the downward circumferential surface of the hole 26 is separated from the support part 19. That is, the position where the stamper 25 is shifted downward by the two clearances due to its own weight becomes the normal position, the stamper 25 can be positioned at a predetermined position, and recording deviations on the disc 3 can be prevented.

FIG. 4 shows a third embodiment, in which a punch 13 is inserted into a through hole 10 provided in a movable die 2 so as to be movable forward and backward relative to a cavity 4. An ejector pin 14 is inserted into the center of the punch 13 so that it can move back and forth relatively, and a cylindrical stamper support member 27 is inserted between the outer peripheral surface of the punch 13 and the inner peripheral surface of the through hole 10 so that it can move back and forth. It is freely mediated. The stamper 25 located inside the cavity 4 at the tip of the stamper support member 27
It supports the inner circumference of. Furthermore, the stamper support member 27
A thin film 28 is provided on the outer peripheral edge of the rear end portion, and this film 28 projects to the rear of the stamper support member 27. This thin film 28 has a wall thickness of 1 mm, is made of rubber with a hardness of 50 to 90H9, and is designed to bend when air pressure is applied.

That is, when releasing the disk 3 from the mold after molding, high pressure air flows into the through hole 10 from the air passage 29 provided in the movable mold 2.
This air passes between the inner circumferential surface of the stamper support member 27 and the punch 13 and presses the disk 3 to release it from the mold, but this air pressure causes the thin film 28 to expand and press against the inner circumferential surface of the through hole 10. closely adhere to. Therefore, air does not leak from between the stamper support member 27 and the through hole 10, and air pressure can be efficiently applied to the disk 3.

In the above embodiment, the thin film 28 was provided on the outer peripheral edge of the rear end of the stamper support member 27 and was made to protrude rearward of the stamper support member 27. However, as shown in FIG. A similar effect can be obtained by providing a thin film 30 made of a thin wall integrally with the outer circumferential edge of the stamper support member 27 at the rear end thereof and projecting the thin film 30 to the rear of the stamper support member 27.

FIG. 6 shows a fourth embodiment, in which a punch 13 is inserted into a through hole 10 provided in a movable die 2 so as to be movable forward and backward with respect to a cavity 4. An ejector pin 14 is inserted into the center of the punch 13 so as to be relatively movable back and forth, and a cylindrical stamper support member 27 is provided between the outer peripheral surface of the punch 3 and the inner peripheral surface of the through hole 10. It is freely intervening. The stamper 25 located inside the cavity 4 at the tip of the stamper support member 27
It supports the inner circumference of. Furthermore, the stamper support member 27
An outer periphery taper 31 is provided on the outer periphery of the rear end portion. A nest 33 having an inner circumferential tapered surface 32 that joins with the outer circumferential tapered surface 31 is inserted between the outer circumferential tapered surface 31 and the inner circumferential surface of the through hole 10 . moreover,
This nest 33 is pressed in the insertion direction by a spring 34 having a spring constant of 5 kg f/mm or more.

Therefore, when releasing the disk 3 from the mold after molding, high pressure air is pumped through the through hole 29 from the air passage 29 provided in the movable mold 2.
This air passes between the inner peripheral surface of the stamper support member 27 and the punch 13 and presses the disk 3 to release it from the mold. Since the stamper support member 27 and the through hole 10 are closed, air does not leak from between the stamper support member 27 and the through hole 10, and air pressure can be efficiently applied to the disk 3.

[Effects of the Invention] As described above, according to claim 1 of the present invention, the spool bushing can move smoothly and the inner periphery of the disk can be punched out easily.

Further, according to the second aspect, it is possible to prevent the stamper installed in the cavity from being misaligned, and it is possible to prevent misalignment of recording.

Furthermore, according to claims 3 and 4, air does not leak from between the stamper support member and the through hole during mold release, and the mold can be easily released by air pressure, and the mold can be manufactured easily, reducing costs. This has the effect of making it possible to achieve the following.

[Brief explanation of drawings]

1 and 2 show a first embodiment of the present invention, FIG. 1 is a vertical side view of a molding die, FIG. 2 is an enlarged sectional view of the main parts, and FIG. FIG. 4 is a front view of a stamper and a stamper support member showing a second embodiment of the present invention; FIG.
The figure is a longitudinal cross-sectional side view of a movable type showing a modification of the third embodiment;
FIG. 6 is a vertical side view of a movable mold showing a fourth embodiment of the present invention, FIG. 7 is a vertical side view of a conventional molding die, and FIG. 8 is a vertical side view of a conventional movable mold. FIG. 9 is a front view of a conventional stamper and a stamper support member. 1... Fixed type, 2... Movable type, 3... Disc,
4... Cavity, 5... Through hole, 6... Spool bush, 13... Punch, 24... Ball guide, 25... Stamper 26... Circular hole, 27...
- Stamper support member, 28.30...thin film, 31...
・Outer circumference tapered surface, 32... Inner circumference tapered surface, 33...
Nested, 34...Spring.

Claims (4)

[Claims] (1) A cavity for molding a disk is provided between a fixed mold and a movable mold, and a spool bush equipped with a gate communicating with a hot runner is provided in the fixed mold so as to be movable in and out of the cavity; For forming a disk, the movable die is provided with a punch that faces the spool bush and can move forward and backward with respect to the cavity, and the punch is moved forward and the spool bush is moved backward to punch out the inner periphery of the disk. A mold for forming a disk, characterized in that the spool bush is supported movably in the axial direction by a ball guide. (2) For disc molding, a cavity for molding a disc is provided between a fixed mold and a movable mold, and a stamper support member is provided in the movable mold to protrude into the cavity and support the circular hole of the stamper. In the mold,
A disk molding die, characterized in that a clearance is provided between the circular hole of the stamper and a stamper support member, and the circular hole of the stamper is eccentrically downward. (3) For disc molding, a cavity for molding a disc is provided between a fixed mold and a movable mold, and a stamper support member is provided in the movable mold to protrude into the cavity and support the circular hole of the stamper. In the mold,
A disk characterized in that the movable mold is provided with a through hole, and the stamper support member is inserted into the through hole, and a thin film is provided on the stamper support member to be brought into close contact with the through hole by air pressure when the mold is released. Molding mold. (4) For disc molding, a cavity for molding a disc is provided between a fixed mold and a movable mold, and a stamper support member is provided in the movable mold to protrude into the cavity and support the circular hole of the stamper. In the mold,
A through hole is provided in the movable mold, and when the stamper support member is inserted into the through hole, an outer peripheral tapered surface is provided on the outer periphery of the rear end of the stamper support member, and the outer peripheral tapered surface and the inner surface of the through hole are connected. A mold for forming a disk, characterized in that a nest having an inner circumferential tapered surface that joins the outer circumferential tapered surface is inserted between the outer peripheral surface and the outer circumferential tapered surface, and the nest is pressed in the inserting direction by a spring.