JPH0620580Y2 - Injection mold for shutter for floppy disk - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial application field" The present invention relates to an injection mold for molding a shutter of a micro floppy disk with resin.

"Prior Art" Generally, as shown in Figs. 5 and 6, a case of a micro-floppy disc has a resin upper half 1 and a lower half 2 for accommodating a storage disc body and outer peripheries of these halves 1 and 2. And a shutter 3 made of stainless steel and having a U-shaped cross section which is slidably attached to the portion. When not in use, the shutter 3 closes the magnetic head inlets 4 and 5 of the halves 1 and 2. Has become.

However, in the case provided with such a stainless steel shutter 3, the resin of each half 1 and 2 is slightly scraped at the edge of the shutter 3 when the shutter is opened and closed, and the scraps adhere to the magnetic disk body to write / write information. It has been pointed out that there are drawbacks such as the possibility of obstructing reading and the high manufacturing cost.

In order to solve this problem, the inventors of the present invention devised to reduce the weight of the shutter by molding the shutter with resin and soften the contact with the half to suppress the generation of shavings. An injection molding die as shown in (3) was actually manufactured and an attempt was made to manufacture a resin shutter. In the figure, reference numeral 10 is a fixed template in which the cavity insert 11 is incorporated,
Reference numeral 12 denotes a movable die plate in which a rectangular plate-shaped core portion 12A is vertically formed, and 13 is a movable side slide core slidably attached along the movable die plate 12, and these slide cores 13 and 13 are An unillustrated angular pin separates the core portion 12A from the core portion 12A when the die is opened and approaches the core portion 12A when the die is closed.

A cavity 14 having the same shape as that of the metal shutter 3 and having side plate molding portions 14A parallel to each other is defined between the cavity insert 11, the core portion 12A, and each slide core 13. Further, an injection nozzle N which penetrates the cavity insert 11 and the fixed mold plate 10 and communicates with the bottom plate molding portion 14B of the cavity is provided.

"Problems to be solved by the invention" However, when the above-mentioned mold is actually used, the resin is not sufficiently injected into the side plate molding portion 14A of one of the cavities 14, and the side plate of the molded shutter is chipped. It was confirmed that the defective shape frequently occurred. Further, even when the molding is successful, each side plate of the molded shutter has a shape that closes toward the front end side due to internal stress, and there is a problem that it takes time and effort to mount the shutter on the cassette half.

Therefore, as a result of the inventors' detailed examination of the cause of the molding failure, in this mold, the molten resin injected from the injection nozzle N flows into the one side plate molding portion 14A as soon as possible due to some reason. When the inner pressure increases, the thin core portion 12A is pressed, and the core portion 12A inclines toward the other side plate molding portion 14A side to narrow the flow path as shown by the chain double-dashed line in the figure, resulting in poor resin filling. As a result, it was revealed that defective shutter molding would occur.

[Means for Solving the Problems] The present invention has been made to solve the above problems, and provides a floppy disk shutter including a pair of side plates facing each other and a bottom plate connecting the side plates in a U-shaped cross section. An injection molding die for integrally molding, which includes a fixed mold plate, a rectangular plate-shaped core part vertically projecting from a movable mold plate facing the fixed mold plate, and both sides of the core part. Between the pair of slide cores provided so as to be able to approach and separate from each other, a cavity that forms the entire shape of the shutter is defined, and the fixed template is provided with an injection nozzle that communicates with the bottom plate molding portion of the cavity, Further, the space between the side plate forming parts of the cavity is formed so as to gradually widen from the bottom plate forming part side toward the tip side of the side plate forming part, thereby improving the strength against collapse of the core part. .

[Embodiment] An embodiment of the injection mold according to the present invention will be described below with reference to FIGS. 1 and 2.

The mold of this embodiment is for molding the floppy disk shutter 15 shown in FIGS. 3 and 4. The shutter 15 will be described. 15A is a side plate, and 15B is a bottom plate that connects the side plates 15A in a U-shape. Each side plate 15A has a window 16 for introducing a head, and one side plate 15A Lower half 2 on the inside
Two guide protrusions 17 that fit in the guide grooves 6 (see FIG. 6) are formed, and a hook portion 18 to which a shutter closing spring is connected is integrally formed on the inner surface of the bottom plate 15B.

The mold of this embodiment has a cavity insert 2 as shown in FIG.
The fixed mold plate 20 in which 1 is incorporated, the movable mold plate 22 that is arranged to face the fixed mold plate 20 and has a rectangular plate-shaped core portion 22A vertically protruding, and slides on the movable mold plate 22. A pair of movable side slide cores 23 that are movably attached are provided, and these slide cores 23 are attached to the fixed die plate 20 by an angular pin (not shown), and the side surface of the core portion 22A when the die is opened. Is separated from the fixed mold plate 20 while being close to the core portion 22A when the mold is closed.
It comes in contact with the inclined surface 20A and is prevented from moving backward. Then, the cavity insert 21, the core portion 22A,
A cavity 24 having a shape corresponding to the shutter 15 is defined between the slide cores 23.

The cavity 24 is composed of a pair of flat plate-shaped side plate molding portions 24A having a uniform void thickness and a bottom plate molding portion 24B connecting the side plate molding portions 24A in a U-shaped cross section. It is formed so as to gradually expand from the child 21 side toward the movable template 22 side. That is, the core portion 22A is formed thick on the movable template 22 side, and the cavity surface of each slide core 23 also has a core portion 22A.
It is formed on the inclined surface corresponding to A.

Here, the distance W2 between the tips of the side plate molding portions 24A, 24A
Is set to a value such that the side plates 15A of the molded shutter 15 approach each other due to internal stress and are substantially parallel to each other. This interval W2 is difficult to specify because the optimum value changes depending on the type of resin, the injection conditions, the size of the shutter 15, etc., but in the experiments conducted by the present inventors, the width W1 of the bottom plate molding portion 24B was determined.
It has been found that a range of 2 to 2.5 times is suitable.
If it is more than 2.5 times, the space between the side plates 15A, 15A of the molded shutter 15 is widened so that it cannot be used. On the other hand, if it is less than 2 times, the conventional defects are not improved.

Further, on the cavity surface of each slide core 23, the window portion forming protrusion 2 that abuts the core portion 22A in the mold closed state.
5 are provided respectively, and one slide core 23 comes into contact with the core portion when the mold is closed, and the guide protrusion 17
And the convex portion 26 forming the hook portion 18 is formed.

Further, as shown in FIG. 2 (a plan view of the front end surface of the core portion), four protruding pins 27 that can be retracted from the center of the front end surface of the core portion 22A are penetrated into the movable mold plate 22 at equal intervals. On the other hand, three injection nozzles N that penetrate the fixed mold plate 20 and the cavity insert 21 and open at equal intervals in the bottom plate molding portion 24B are provided. In FIG. 2, 28 is the gate.

In order to use the injection molding die having the above structure, first, in the mold closed state shown in the drawing, ABS melted from each nozzle N ...
A resin such as the above is injected, and when the resin is sufficiently solidified, the fixed mold plate 20 and the movable mold plate 22 are opened. Then, each slide core 23 retracts from the molded product along the movable mold plate 22 by the angular pin, and then the molded product is released from the molded product by the ejection pins 27.

According to the above mold, the nozzle N ...
Even if the resin flows into the one side plate molding portion 24A earlier due to some reason when the molten resin is injected into the core, the thickness of the core portion 22A is thicker on the movable template 22 side, and the strength against collapse is the same as that of the conventional product. Since it is higher than
It is possible to prevent defective molding of the shutter 15 because A does not fall to the side plate molding portion 24A side and block the flow path.

Further, the shutter 15 formed by this mold is deformed in a direction in which the side plates close to each other due to internal stress after the mold is released, and becomes substantially parallel. Therefore, there is an advantage that the upper and lower halves can be easily mounted when the floppy disk is assembled.

The present invention is not limited to the above-described embodiment, but the detailed shape of the shutter, the operating structure of each slide core, and the like may be appropriately changed.

[Advantage of Invention] As described above, according to the injection molding die for the shutter for the floppy disk of the present invention, when the molten resin is injected from the nozzle into the bottom plate molding portion of the cavity, both are caused by some cause. Even if the resin does not flow into the side plate molding part of at a uniform flow rate, the thickness of the core part is thick on the base end side,
Since the strength against falling down is high, the core part does not fall down to one side plate forming part side to block the flow path, and defective molding such as chipping of the shutter side plate can be prevented.

Also, the shutter molded with this mold, after releasing the mold,
Since the side plates are deformed in the direction of closing each other by the internal stress and become substantially parallel to each other, there is an advantage that the half plates can be easily mounted when the floppy disk is assembled.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of an injection molding die according to the present invention,
FIG. 2 is an explanatory view of the main part, and FIGS. 3 and 4 are a side view and a plan view showing a shutter molded by this mold. Further, FIGS. 5 and 6 are a plan view and a bottom view showing a general floppy disk, and FIG. 7 is a sectional view showing a problem of a conventional injection molding die. 15 ... Shutter, 15A ... Side plate, 15B ... Bottom plate, 20 ... Fixed mold plate, 21 ... Cavity insert (part of fixed mold plate), 22 ... Movable mold plate, 22A ... Core part, 23 ... Movable slide core, 24 ... Cavity, 24A ... Side plate molding part, 24B ... Bottom plate molding part.

Claims (1)

[Scope of utility model registration request] 1. An injection molding die for integrally molding a shutter for a floppy disk, which comprises a pair of side plates facing each other and a bottom plate connecting the side plates in a U-shaped cross section.
A fixed mold plate, a rectangular plate-shaped core portion vertically projecting from a movable mold plate facing the fixed mold plate, and a pair of slide cores provided so as to approach and separate from both surfaces of the core portion. A cavity forming the overall shape of the shutter, an injection nozzle communicating with the bottom plate forming part of the cavity is provided in the fixed mold plate, and the gap between the side plate forming parts of the cavity is the bottom plate forming part. An injection molding die for a shutter for a floppy disk, which is formed so as to gradually expand from the side of the side plate toward the tip side of the side plate molding portion.