JPH0817022B2 - Shutter molding method for disc cassette - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a disk cassette having a flexible disk housed in a hard case, and more particularly, a shutter for opening and closing a head insertion opening.

[Background technology and problems]

There is known a magnetic disk cassette in which a flexible magnetic disk having a diameter of 3.5 inches is housed in a hard case and digital data can be recorded and reproduced in this state. A shutter is attached to the magnetic disk cassette so as to be openable and closable in order to protect the magnetic disk. That is, the shutter is opened only during operation, the magnetic disk is exposed through the slot-shaped head insertion opening provided in the case, and when not operating, the shutter is closed and the opening is closed. By closing the opening in this way, foreign matter and dust are prevented from entering the case, and the magnetic disk in the case is protected.

Conventionally, this shutter has a U-shaped cross section made of metal such as stainless steel. A long hole having substantially the same shape as the opening of the case was formed in the shutter, and this shutter was slidably attached to the case. This shutter needs to be attached to the case so that it slides smoothly and does not easily come off from the case. Further, it is necessary to prevent dust from entering the cassette by uniformly adhering to the outer surface of the case and completely closing the opening. Therefore, the height of the opening of the shutter that holds the cassette case and the height of the guide projection in the shutter must be strictly determined to correspond to the standardized thickness of the cassette case.

A conventional shutter is made of metal such as stainless steel, and is processed by performing processes such as punching, bending, and deburring on a flat plate of stainless steel. However, since the stainless steel flat plate is stored in a rolled state, stress may remain and it may be deformed. Therefore, it is difficult to perform highly accurate processing in the bending process.

Further, in the conventional shutter, when the shutter is attached to the case or when the shutter slides on the hard case, the hard case may be scraped by the guide projections, and dust generated by this may get into the case. was there. Further, since the metallic material is used, it is difficult to color the shutter and print the display of the manufacturer on the shutter. As described above, the conventional shutter has a large number of manufacturing steps, and the dimensional accuracy is severely required. Therefore, the shutter has to be expensive.

These problems can be solved by using a synthetic resin shutter. However, when the guide projections are integrally formed, the projections are erected at a right angle between the upper plate and the lower plate of the shutter. There was a difficult problem.

[Object of the Invention]

Therefore, an object of the present invention is to provide a method of molding a shutter of a disk cassette, in which a guide projection can be integrally molded with the shutter without using a mold having a complicated structure.

[Means for solving the problem]

The present invention is a shutter which has a U-shaped cross section so as to sandwich a case in which a disc is rotatably housed, and which is slidably attached to the case for opening and closing a head insertion opening provided in the case. In order to form the upper plate and the lower plate of the shutter and the side plate connecting the upper plate and the lower plate, the upper plate, the lower plate and the side that are the inner surface side of the U-shaped cross section of the shutter. The core for forming the inner surface side of the face plate is arranged, and the cavity for forming the outer surface side of the upper surface plate, the lower surface plate and the side surface plate, which are the outer surface side of the U-shaped cross section of the shutter, is made Of the shutter, the upper plate of which is substantially continuously connected to the inner wall of the side plate, and the lower plate of the shutter, and the inner wall of the side plate facing the inner side of the lower plate at the lower end of the notch. Extends in a substantially parallel direction In order to form a protrusion, the cavity is provided with a slide core insertion port on the side where the bottom plate of the shutter is formed, and the core has
On the surface forming the inner wall of the side plate of the shutter, and at the position corresponding to the slide core insertion opening, a recess and a step formed on the bottom surface of the recess are provided, and from the slide core insertion opening of the cavity. A disc, which is inserted, slides in the cavity, has a slide core whose tip fits into the recess of the core, and is injection-molded with a synthetic resin using the core, the cavity, and the slide core. This is a method for forming a cassette shutter.

According to the present invention, the notch is provided, and the slide core is inserted through the notch so that the protrusion can be formed. Therefore, the structure of the mold is simple, and the shutter having the protrusion can be easily molded. .

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1A and 1B are a top view and a bottom view of the entire magnetic disk cassette having a shutter molded according to the present invention.

In FIGS. 1A and 1B, 1 is an upper shell and 2 is a lower shell. The upper shell 1 and the lower shell 2 are
For example, it is an ABS resin molded product containing an antistatic agent. A liner made of non-woven fabric such as rayon is attached to the inner surfaces of the upper shell 1 and the lower shell 2 by thermal welding or ultrasonic welding in order to prevent the magnetic disk from being dropped out, worn and static electricity. The outer peripheral portion of the upper shell 1 and the outer peripheral portion of the lower shell 2 are joined by ultrasonic welding, and the magnetic disk 3 is housed in a case in which the upper shell 1 and the lower shell 2 are united. The magnetic disk 3 is a flexible magnetic disk based on a disk-shaped polymer film and having a magnetic layer formed uniformly on the lower surface thereof. A circular opening is formed in the center of the magnetic disk 3,
A ring-shaped center plate 4 is fixed to this opening. A substantially square motor shaft insertion hole 5 is formed in the center of the center plate 4, and a rectangular position regulating pin insertion hole 6 is provided at a position offset from the insertion hole 5 by a predetermined distance.
Are formed. Circular opening 7 in the center of the lower shell 2
Is formed, and the center plate 4 is arranged in the opening 7 with some play. Oblong holes 8 and 9 are formed in the upper shell 1 and the lower shell 2, and the magnetic disk 3 is exposed from the oblong holes 8 and 9.

Recesses 10 and 11 are formed on the outer surfaces of the upper shell 1 and the lower shell 2 including the portions where the long holes 8 and 9 are formed,
A shutter 12 having a U-shaped cross section shown in FIG. 2 is slidably mounted in the recesses 10 and 11. A guide groove 13 is provided along the side edge portion of the outer surface of the lower shell 2, and a projection protruding inside the shutter 12 is guided in the guide groove 13. As shown by the solid lines in FIGS. 1A and 1B, the slot 9 for inserting the head, the slot 8 for inserting the head pad, and the slots 14 and 15 formed in the shutter 12 coincide with each other, and A used state in which the disk 3 is exposed to the outside, and an unused state in which the elongated holes 8 and 9 are closed and the magnetic disk 3 is covered by the shutter 12 as shown by phantom lines in FIGS. 1A and 1B. Shutter 12 so that
Slides. The shutter 12 protects the magnetic disk 3 and prevents dust from entering.

Further, a lug 16 for preventing erroneous erasure is provided at one corner portion of the lower shell 2, and if the lug 16 is folded and removed, it cannot be erased. This lower shell 2
A pair of positioning holes 17 and 18 are provided at the two corners of the disk for positioning when the magnetic disk cassette is mounted on the disk recorder body. One of the positioning holes 17 is a long hole so that even if there is some error in the position of the hole, it can be tolerated. The other two corners not provided with the positioning holes 17 and 18 serve as reference planes, and the magnetic disk cassette is supported at the reference positions at the four corners. In this state, the magnetic disk 3 is rotated by a motor to record or reproduce a digital signal or an analog signal.

FIG. 2 is a front view, a bottom view and a side view of the shutter 12. The shutter 12 includes a top plate 21, a side plate 23, and a bottom plate 22.
Is integrally molded. The shutter 12 is made of a thermoplastic synthetic resin having excellent elasticity, low frictional resistance, and relatively high strength, such as polyoxymethylene resin. The shutter 12 has a U-shaped cross section, and when it is detached from the case, as shown in FIG. 2C and FIG.
And the lower surface plate 22 are close to each other.

The upper plate 21 and the lower plate 22 have elongated holes 14 and 15, respectively. The lower surface plate 22 is formed with, for example, two rectangular cutouts 24 and 25, and along the inner edges of the cutouts 24 and 25, so as to face the side surface plate 23, a guide projection 26 and
27 are formed. Further, the side plate 23 is formed with a protrusion 28 for locking the spring, which protrudes inward.

The opening of the shutter 12 is widened, and the shutter 12 is mounted so that the case is inserted through the opening. In this mounted state, the inner surfaces of the upper plate 21 and the lower plate 22 are the surfaces of the upper shell 1 and the lower shell 2, respectively. The shutter so that
12 pinch the case. A spring is interposed between the inside of the side plate 23 of the shutter 12 and the end surface of the case.
The shutter 12 is the recess 10 of the upper shell 1 and the lower shell 2.
Sliding through 11 and 11, the slots 8 and 9 are opened and closed. When the magnetic disk cassette is not used, the upper plate 21 and the lower plate 22 of the shutter 12 close the elongated holes 8 and 9 due to the tension of the spring interposed between the shutter 12 and the cassette case, and the magnetic disk 3 is closed by the shutter 12. Be kept covered by.

As described above, the upper plate 21 and the lower plate 22 of the shutter 12 are arranged so as to be closer to each other toward the peripheral edge of the opening end. It is evenly adhered to the bottom surfaces of the recesses 10 and 11 of the lower shell 2.

FIG. 4 is an enlarged view of a part of the magnetic disk cassette shown in FIG. The protrusion 27 of the shutter 12 is slidably inserted into the guide groove 13, and the protrusion 26
Is similarly slidably inserted into the guide groove 13. One end 32 of the spring 31 is inserted and locked in a recess 33 formed in the cassette shell. The other end 34 of the spring 31 is locked to the spring locking projection 28 of the shutter 12.

FIG. 4 shows a state in which the shutter 12 is biased to a non-use position by the spring 31. When the magnetic disk cassette is mounted on the disk recorder main body at the time of use, the shutter 12 is automatically moved against the spring force of the spring 31 by the operating portion of the disk recorder main body along with the sliding operation at the time of mounting. Then, the elongated holes 14 and 15 of the shutter 12 and the elongated holes 8 and 9 of the upper shell 1 and the lower shell 2 are in the same operating state.

The present invention relates to a method of molding the shutter 12 of the disc cassette as described above. Shutter 12
Specifically, it is molded by injection molding. Injection molding is performed by injecting a synthetic resin from a gate into a space formed by two molds including a core and a cavity.

The mold for this purpose is to form the core 42 and the cavity 44 for forming the overall shape of the shutter 12 and the elongated holes 14 and 15 of the shutter 12, respectively, as shown in FIGS. The slide cores 51 and 52 and the projections 26 of the shutter 12 for forming the projections 26 of the shutter 12
And a slide core 56 for forming the protrusion 28.

The notch 24 corresponding to the position of the slide core 55 is formed to form the protrusion 26 inside the shutter 12,
A notch 25 corresponding to the position of the slide core 56 is formed to form the protrusion 27 and the protrusion 28 inside the 12. Here, the protrusion 27 is formed in contact with the peripheral portion of the cutout 25, and the protrusion 28 is formed in the inner space corresponding to the position of the cutout 25.
Is projected from. Therefore, one slide core 56 can form both of the two protrusions 27 and 28.

5A and 5B are a front view and a side view of a mold for molding the shutter 12 described above. FIG. 6 is of FIG.
AA 'line sectional view, FIG. 7 is a BB' line sectional view of FIG. 5, 8
The drawing is a sectional view taken along the line CC 'in FIG. The core 42 fitted in the cavity 44 includes the upper plate 21, the lower plate 22, and the lower plate 22 of the shutter 12.
It has a convex portion 41 having the same shape as the internal space formed by the side surface plate 23. A gate 58 for injecting the molten synthetic resin into the mold is provided at the top of the cavity 44.

As shown in FIG. 8, on the tip surface of the convex portion 41 of the core 42,
Recesses 45, 46 into which the ends of the slide cores 55, 56 are inserted are provided. The concave portion 45 has a depth equal to the width of the convex portion 41 as shown in FIG. 6, and the concave portion 46 has a depth to the formation position of the protrusion 28 as shown in FIG. Steps 47 and 48 are formed on the bottom surfaces of the recesses 45 and 46, respectively. The shapes of the step portions 47 and 48 correspond to the protrusions 26 and 27, respectively.

A slide core insertion opening having a shape corresponding to the elongated holes 14 and 15 of the shutter 12 is formed on the front surface and the back surface of the cavity 44, and the slide cores 51 and 52 are slid through these insertion openings. On the front surface of the cavity 44, as shown in FIGS. 5 and 10, slide core insertion ports 59, 60 into which rod-shaped slide cores 55, 56 are respectively inserted are formed. The positions of the slide cores 55 and 56 are the notches 24 and 25 of the shutter 12.
Becomes As shown in FIG. 7, a step portion 57 having a shape corresponding to the protrusion 28 of the shutter 12 is formed at the tip of the convex portion 41 of the core 42 that abuts the tip of the slide core 56.

Molten resin, such as polyoxymethylene resin, is injected from the gate 58 into the mold, and slide cores 51, 52
This resin flows into the space between the core 44 and the cavity 44 into which the holes 55 and 56 are inserted. Then, the resin is cooled and solidified in the mold. In this case, regarding the surface temperature of the mold, the surface temperature of the cavity 44 is set lower than the surface temperature of the core 42. Therefore, this solidification starts from the resin around the cavity 44.

After the liquid resin is cooled and solidified in the mold, the slide cores 51, 52 and 55, 56 are slid laterally by a predetermined distance as shown in FIG. The mold is separated as shown in FIG. The shutter 12 having the shape shown in FIG. 2 is taken out of this mold. In other words, the liquid resin is poured into the gap between the cavity 44 and the core 42, so that the top plate 21, the bottom plate 22, and the side plate
23 is formed.

As shown in FIG. 5, slide cores 51 and 52 are inserted into the cavity 44, and resin does not flow into this portion, and elongated holes 14 and 15 are formed therein. Slide core 55
And 56 are inserted in the cavity 44, and the resin does not flow into this portion, and the notches 24 and 25 are formed therein. A step portion 47 is formed in the concave portion 45 at the tip of the convex portion 41 of the core 42, and a gap is formed by the step portion 47 while the core 42 and the slide core 55 are in contact with each other, and the resin flows into this gap. The protrusion 26 is formed. As shown in FIG. 6, FIG. 7 and FIG. 8, a step portion 48 is formed in the concave portion 46 at the tip of the convex portion 41 of the core 42, and the step portion 48 forms the core 42 and the slide core 56.
A void is formed while and are in contact with each other, and the resin flows into this void to form the protrusion 27. At the same time, since the step 57 is formed at the tip of the protrusion 41, the resin flows into the step 57 and the protrusion 28 is formed.

As described above, the surface temperature of the mold is controlled so that the surface temperature of the cavity 44 is lower than the surface temperature of the core 42.
Therefore, the resin in the vicinity of the surface of the cavity 44 contacts the core 42.
The resin is solidified faster than the resin in the vicinity of the surface. Therefore,
The volume reduction near core 42 occurs later than the volume reduction near cavity 44. This distortion is released after it is taken out of the mold, so that the shutter 12 is released as shown in FIG.
And, as shown in FIG. 3, it is curved inward so that the opening end becomes narrow.

Although the shutter 12 has two guide protrusions in this embodiment, the guide protrusion is not limited to two, and three guide protrusions may be provided, for example.

〔The invention's effect〕

According to the present invention, since the shutter is made of synthetic resin, the manufacturing process can be simplified and the manufacturing cost can be reduced. Further, according to the present invention, the notch 24 corresponding to the position of the slide core 55 is formed in order to form the projection 26 for guiding the shutter, and the projection 27 for guiding is formed in the slide core 56. The notch 25 corresponding to the position is formed. Therefore, there is an advantage that the structure of the mold for integrally molding these guide protrusions 26 and 27 with the shutter is not complicated.

[Brief description of drawings]

FIG. 1 is a top view and a bottom view of an example of a disc cassette to which the present invention can be applied, FIG. 2 is a front view, a bottom view and a side view of a shutter in this disc cassette, and FIG. 3 is a sectional view of the shutter. FIG. 4 is a partially enlarged view of the shutter, FIG. 5 is a front view and a side view of an example of a mold for molding the shutter in one embodiment of the present invention, and FIGS. 6, 7, and 8 are A sectional view of an example of a die for molding a shutter in one embodiment of the present invention, and FIGS. 9 and 10 are sectional views used for explaining an example of a die for molding a shutter in one embodiment of the present invention. . 1: Upper shell, 2: Lower shell, 3: Magnetic disk, 12: Shutter, 13: Guide groove, 21: Top plate, 22: Bottom plate, 23: Side plate, 24, 25: Notch, 26, 27: Protrusion, 31: Spring, 42: Core, 44: Cavity, 51, 52, 55, 56: Slide core

Claims (1)

[Claims] 1. A U-shaped cross-section so as to sandwich a case in which a disk is rotatably accommodated, and is slidable in the case for opening and closing a head insertion opening provided in the case. In the method for forming a shutter to be mounted, the shutter is the inner surface side of the U-shaped section in order to form an upper plate and a lower plate of the shutter and a side plate connecting the upper plate and the lower plate. The core for forming the inner surface side of the upper surface plate, the lower surface plate and the side surface plate is arranged, and the outer surface of the upper surface plate, the lower surface plate and the side surface plate which is the outer surface side of the U-shaped cross section of the shutter. A cavity for forming a side is arranged so as to be movable relative to the core, and a cutout portion is provided on the lower surface plate of the shutter, the upper end of which is substantially connected to the inner wall of the side surface plate, this In order to form a protrusion extending in a direction substantially parallel to the inner wall of the side plate toward the inner side of the lower plate at the lower end of the cutout portion, the slide core is formed in the cavity on the side where the lower plate of the shutter is formed. The core is provided with an insertion opening, and the core has a concave portion and a stepped portion formed on the bottom surface of the concave portion on the surface forming the inner wall of the side plate of the shutter and at a position corresponding to the slide core insertion opening. And a slide core that is inserted from the slide core insertion opening of the cavity, slides in the cavity, and has its tip fitted in the recess of the core. A method of molding a shutter for a disk cassette, which is characterized in that it is injection-molded with a synthetic resin by using.