JPS63206911A - Metallic mold device for production of magnetic disk substrate - Google Patents

Abstract

PURPOSE:To improve the mold release properties and to prevent the deformation or warp of a magnetic disk substrate when it is released from a metallic mold, by blowing the heated air into the metallic mold at the mold release time. CONSTITUTION:An air blowing means 4 consists of the air paths 12 formed into the heat boards 11 set above and under a metallic mold main body 6 and an air blowing machine which feeds the air into the paths 12 via pipes 20 and a dispenser 13. Then the air heated properly in the paths 12 of the boards 11 is blown into the center of a metallic mold 2 by a sprayer 7 and through gaps 3a and 3b of an ejector pin inserting hole 9. Thus a vacuum state is eliminated between a molded magnetic disk substrate 1 and the mold 2. As a result, the mold release properties can be improved and the deformation or warp of the substrate 1 can be avoided when it is released from the mold 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a magnetic disk substrate molding device for injection molding a magnetic disk substrate in a state before forming an underlayer and a magnetic layer of a magnetic disk (hard disk).

[Background technology]

Conventionally, magnetic disks called hard disks have been used as recording media for computers, personal computers, word processors, and the like. There is currently a movement to reduce costs by shifting from aluminum alloy magnetic disk substrates to those using heat-resistant plastic materials as magnetic disk substrates for this type of magnetic disk.

The surface roughness required for resin magnetic disk substrates is R, □
The surface roughness is less than 0.08μm and the flatness is less than 10μm/Φ951, which requires extremely precise injection molding technology.Since the surface roughness is transferred to the surface roughness of the injection mold, mirror finishing of the mold is required. It is thought that this can be handled with technology.

There are various factors that cause flatness, such as thermal deformation due to non-uniform resin fluidity, stress deformation due to poor mold release, etc., and no solution has been found yet.

In particular, when the surface of the mold is mirror-finished, the mold is in close contact with the magnetic disk substrate, which is a molded product, and when the mold is pushed up with an ejector pin, the interior momentarily becomes a vacuum state. If this is pushed up forcibly, deformation will occur.

Therefore, we considered blowing air during demolding, but due to the nonuniform temperature of the supplied air, the temperature distribution of the demolded magnetic disk substrate becomes nonuniform, causing subtle deformation. The flatness required for magnetic disk substrates is so strict that even such subtle deformations cannot be used.

[Purpose of the invention]

An object of the present invention is to provide a magnetic disk substrate molding device that is free from deformation during mold release, provides sufficiently stable flatness, and has good mold releasability.

[Disclosure of the invention]

The magnetic disk substrate molding device of the present invention includes a mold for injection molding a magnetic disk substrate, an air blowing means for blowing air into a cavity from a gap between constituent members of the mold, and a blowing means for blowing air into a cavity from a gap between constituent members of the mold. It is equipped with an air heating means for heating the air.

According to this configuration, by blowing heated air into the mold at the time of mold release, the vacuum state between the molded magnetic disk substrate and the mold is eliminated, and the mold releasability is improved. Therefore, deformation and warping of the magnetic disk substrate during demolding can be prevented. Furthermore, since heated air is blown in, unlike the case where cold air is blown in, temperature non-uniformity of the released magnetic disk substrate is eliminated, and the flatness is further improved.

Furthermore, since mold releasability is improved, workability is also improved.

Embodiment An embodiment of the present invention will be explained based on FIGS. 1 and 2. This magnetic disk substrate molding device includes a mold 2 for injection molding a magnetic disk substrate 1, an air blowing means 4 for blowing air into a cavity 2a from gaps 3a and 3b between constituent members of the mold 2. The air heating device 5 is provided with an air heating device 5 for heating the air blown by the air blowing device 4. FIG. 2 shows a molded magnetic disk substrate 1, in which a center hole lb is formed in the center by secondary processing and the gate 1a is removed.

The mold 2 has a mold body 6 and a sprue 7, each of which constitutes the mold, and an ejector pin 8 is inserted into an ejector pin insertion hole 9. The mold body 6 is a stationary mold body 6a.
and a movable mold body 6b. The air blowing means 4 includes an air passage 12 in a hot platen 11 provided above and below the mold body 6, and a blower (not shown) that blows air into this air passage 12a via a pipe 20 and a dispenser 13.

The heating plate 11 has a heater lO embedded therein, and the heater 10 is controlled by a temperature controller 14 to heat the air in the air passage 12 to an appropriate temperature. The temperature controller 14 is connected to a temperature sensor 19 provided in the mold body 6. Air heating means 5 using these heating plates 11, heaters 10, etc.
is configured.

The air passages 12 for the upper and lower heat g111 open into gaps 3c and 3d between these heating plates 11 and the mold body 6, respectively.
c and 3d communicate with the gaps 3a and 3b. The gap 3a is formed between the ejector pin 8 and the ejector pin insertion hole 9. The gap 3b is formed between the sprue 7 and the mold body 6. Gap 3a, 3
b is approximately 0,005 to 0.01 mm, respectively. There is an air passage 12 between the lower heating plate 11 and the mold body 6.
A gap 3 that communicates the opening of the ejector pin insertion hole 9 with the ejector pin insertion hole 9.
A sealing material 16, 17 is provided to seal d. A sealing material 15 is provided between the upper heat 111 and the mold body 6 to seal the gap 3c. The sealing materials 15 to 17 are made of O-rings or the like.

According to this configuration, by blowing air moderately heated in the air passage 12 in the heating plate 11 into the center of the mold 2 through the gaps 3a and 3b between the sprue 7 and the ejector pin insertion hole 9, the magnetic The vacuum state between the disk substrate 1 and the mold 2 is eliminated, and mold releasability is improved. Therefore,
Deformation and warping of the magnetic disk substrate 1 during demolding can be prevented. Since heated air is blown, unlike the case where cold air is blown, temperature non-uniformity of the released magnetic disk substrate 1 is eliminated, and the flatness is further improved.

Furthermore, since mold releasability is improved, workability is also improved. By using the dispenser 13, air is blown in a timely manner at the same time as the mold is opened. Since the air is heated in the air passage 12 within the heating plate 11, it can be heated uniformly. Also, a gap 3a between the sprue 7 and the ejector pin insertion hole 9 located on the fixed side and the movable side of the mold 6, respectively.
, 3b, so that it is uniformly supplied to both the upper and lower surfaces of the molded magnetic disk substrate I over the entire circumference. As a result, the mold releasability and the flat k1 degree can be further improved.

〔Effect of the invention〕

According to the magnetic disk substrate mold device of the present invention, by blowing heated air into the mold during demolding,
The vacuum state between the molded magnetic disk substrate and the mold is eliminated, improving mold releasability. Therefore, deformation and warping of the magnetic disk substrate during demolding can be prevented. Furthermore, since heated air is blown in, unlike the case where cold air is blown in, temperature non-uniformity of the released magnetic disk substrate is eliminated, and the flatness is further improved. Furthermore, since mold releasability is improved, workability is also improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a perspective view of the magnetic disk substrate. 1... Magnetic disk substrate, 2... Mold, 3a, 3b
...Gap, 4.Air supply means, 5.Air heating means, 6.Mold body, 7.Sprue, 8.
...Ejector pin, 11...Heating plate

Claims (1)

[Claims] A magnetic mold comprising a mold for injection molding a magnetic disk substrate, an air blowing means for blowing air into the cavity from a gap between the constituent members of the mold, and an air heating means for heating the air blown by the air blowing means. Disc substrate mold equipment.