JP3309668B2 - Mold for resin shutter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for molding a resin shutter of a magnetic disk such as a floppy disk or a magneto-optical disk formed by injection molding of a thermoplastic resin.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 3, a diskette of a magnetic disk has a resin shell 2 for accommodating a storage disk 1 and a U-shaped cross section slidably mounted on an outer peripheral portion of the shell 2. And a resin shutter 3 in the shape of a letter. Then, in a non-use state extracted from a magnetic disk unit (not shown) connected to a computer or the like, the magnetic head inlets 4 of each shell 2 are closed by the resin shutter 3, and the storage disk 1 is externally mounted. It is designed to protect from dust and the like.

As shown in FIG. 4, a resin shutter 3 used for such a magnetic disk 5 comprises a pair of opposed side plates 6, 7 and a connecting portion 8 for connecting the side plates 6, 7 to each other. It is common to integrally mold into a U-shaped cross section having a certain thickness. A window 9 is provided in each of the side plate portions 6 and 7 of the resin shutter 3 so as to communicate with the magnetic head inlet 4 provided in the shell 2.
Are provided with small windows 11 and 12 for forming slide projections housed in rail grooves (not shown) provided in the shell 2 so as to protrude toward the inner surface side. The spring hooking projection 13 is formed using one of the small windows 11.

The resin shutter 3 having such a configuration is generally formed by a molding die 14 as shown in FIGS. As shown in FIG. 5, the molding die 14 is, for example, a fixed die 16 fixed to an upper fixed die plate 15, and is brought into and away from the fixed die plate 15 from below. A movable mold 18 attached to the movable mold plate 17.

The movable mold 18 is composed of three divided molds 20, 21, and 22. These are a core mold 20 fixed to the movable mold plate 17, and a core mold 20 mounted on the movable mold plate 17 so as to be movable in the horizontal direction, and the slide mold 19 moves the movable mold plate 17. And a pair of slide molds 21 and 22 which are brought into and out of contact with the slide mold 20. Reference numeral 19a denotes a guide part that constitutes the slide mechanism 19, and 19b denotes a spring that urges the slide die in the horizontal direction.

[0006] As shown in FIG.
A recess 16a for molding the connecting portion 8 of the resin shutter 3
Is provided on each slide mold 21, 22 for forming the side plate portions 6, 7 of the resin shutter 3.
a, 22a are provided.

As shown in FIG. 5, a pair of slide molds 21 and 22 have a pair of inclined surfaces 21b arranged so as to gradually decrease the width toward the fixed mold 16 arranged above.
22b are provided respectively. On the other hand, locking blocks 23 and 24 having inclined surfaces 23a and 24a that come into contact with the inclined surfaces 21b and 22b when the mold is closed are provided on both sides in the horizontal direction of the fixed mold 16 opposed to the inclined surfaces 21b and 22b. ing. These inclined surfaces 21b,
22b, 23a and 24a allow the slide dies 21, 2
2 is a core mold 2 that resists the urging force of the spring 19b according to the mold clamping force between the fixed mold plate 15 and the movable mold plate 17.
It is configured to be pressed toward zero.

The fixed mold 16 and the locking blocks 23 and 24 are fixed to the fixed mold plate 15 by fastening means such as bolts, with an appropriate shim 25 for position adjustment therebetween. . When the fixed mold 16 and the movable mold 18 are closed, the slide dies 21, 22 and the fixed mold 16, the slide mold 21,
The core mold 22 and the core mold 20 are pressed tightly.

As a result, the cavity 26a of the connecting portion 8 is formed by the recess 16a of the fixed die 16 and the upper end surface 20a of the core mold 20 shown in FIG. Also, the concave mold wall surfaces 21a, 22a of the slide molds 21, 22 and the core mold 20
Of the side plate portions 6 and 7 by the side surface 20b of
b, 26c are formed.

These cavities 26a, 26b, 26
c has a substantially constant cross-sectional shape, and the cavities 26a of the connecting portions 8 have cavities 26b of the side plate portions 6 and 7 at both ends in the width direction (that is, the thickness direction of the core mold 20). 26c. Also,
The fixed mold 16 forming the cavity 26a of the connecting portion 8 is provided with a gate 27 for injecting the molten resin supplied from an injection molding machine (not shown) into the cavity 26a.

In order to mold the resin shutter 3 of FIG. 3 with the molding die 14 having the above-described structure, the movable mold plate 17 is operated with respect to the fixed mold plate 15 as shown in FIG. With the mold 16 and the movable mold 18 closed, molten resin is injected from the injection molding machine into the formed cavity 26. The injected molten resin is applied to the gate 2 as shown in FIG.
7 is introduced into the cavity 26a of the connecting portion 8, and the two side plate portions 6, while expelling the air in the cavity 26,
7 and are flowed toward the lower ends of the cavities 26b, 26c of the side plates 6, 7, respectively. Then, the molten resin is cooled and cured while being completely filled in the cavity 26, whereby the resin shutter 3 having a U-shaped cross section is formed.

Since the side plates 6 and 7 have extremely small thicknesses of 0.35 to 0.38 mm, the cavities 26b of the side plates 6 and 7 are formed during molding.
In order to reach the molten resin to the lower end of 26c, an extremely high injection pressure is required. For this reason, in order to form the pair of side plate portions 6 and 7 into uniform thickness dimensions, the molten metal injected from the gate 27 into the cavity 26a of the connecting portion 8 and distributed to the cavities 26b and 26c of the side plate portions 6 and 7 is formed. It is necessary to set the resin flow balance evenly.

[0013]

However, in the conventional molding die 14, the cavities 2 of the two side plates 6, 7 are formed.
If the molten resin is not allowed to flow simultaneously and evenly into the 6b, 26c at a uniform flow rate, the resin pressure in each of the cavities 26b, 26c will be different, and a flat plate-like shape with the upper end face 20a as a free end will be used. It is conceivable that the core mold 20 is deformed by the pressure difference between the cavities 26b, 26c of the both side plate portions 6, 7. Here, the core mold 20 is provided with the cavities 26 b and 26 of the pair of side plate portions 6 and 7.
c, the cavities 26b, 2b of the side plates 6, 7
7 includes a thin plate portion 20A shown in FIG. 7 and a thick plate portion 20B extending at a base end of the thin plate portion 20A and supporting the thin plate portion 20A. The portion 20A is formed with a uniform thickness up to both ends in the width direction (the directions of arrows A and B in the figure). That is, as shown in FIG. 6, the cavities 26b and 26c are actually
Is formed by the thin plate portion 20A, it is conceivable that the thin plate portion 20A is deformed by the pressure difference between the cavities 26b and 26c. As a result, in the cavities 26b (26c) of the side plates 6, 7 on the side where the resin pressure is high,
There is an inconvenience that a large amount of molten resin flows in and the thickness of one side plate portion 6 (7) is thickened.

In particular, in the resin shutter 3, since the small windows 11 and 12 for forming the slide projections are provided on only one of the side plate portions 6, both side plate portions 6 and 7 are provided.
There is an area difference between them. For this reason, it is difficult to balance the flow rate of the molten resin to both cavities 26b and 26c only by forming the designed thickness dimensions of the cavities 26b and 26c of both side plate parts 6 and 7 uniformly.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a molding die for a resin shutter capable of equalizing the thickness of two side plates connected by a connecting portion. It is an object.

[0016]

According to a first aspect of the present invention, there is provided a resin shutter molding die having a pair of opposed side plate portions and a connecting portion connecting the side plate portions, and having a U-shaped cross section. A molding die for integrally molding a resin shutter, comprising: a fixed mold having a cavity of a connecting portion and a gate communicating with the cavity; and a pair of molds which are brought into contact with and separated from the fixed mold and communicate with the cavity of the connecting portion. A movable mold forming a cavity of the side plate portion, and the movable mold is disposed in a direction intersecting a core mold disposed between the cavities of the side plate portion and a moving direction of the movable mold with respect to the core mold. A pair of slide dies that are separated from and separated from each other to form a cavity of a side plate portion with the core mold, wherein the core mold has a thin plate portion disposed between the cavities of the pair of side plate portions; Extends to the base end of the to support the thin plate Characterized in that it comprises a plate portion and a pair of support walls which are fixed to the thick plate portion with at both ends in the width direction of the thin plate portion is opposed is fixed.

Therefore, even when the molten resin is injected under high pressure into the cavity of the pair of side plates formed in the gap between the core mold thin plate and the pair of slide molds, the thin plate of the core mold remains The pair of support walls prevent deformation in the thickness direction.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a molding die for a resin shutter according to the present invention will be described below with reference to FIGS. The resin shutter molding die 100 of this embodiment is obtained by improving the configuration of the core die 20 in the conventional resin shutter molding die shown in FIG. Therefore, the same parts as those in the conventional example are denoted by the same reference numerals, and description thereof will be omitted. In the present embodiment, the movable mold 18 shown in FIG. 5 is a movable mold 50, and its core mold 20 is a core mold 40.

FIG. 2 is a view of the movable mold 50 of the molding die 100 of the present embodiment as viewed from the fixed mold 16 shown in FIG. 5, and the movable mold 50 shown in FIG. In the movable die 18, a core die 20 is improved. The core mold 40 includes cavities 26b of the pair of side plates 6,7,
26c, which is disposed between the side plates 6 and 7
b and 26c together with the pair of slide dies 21 and 22, and a thick plate portion 42 extending to the base end 41a of the thin plate portion 41 and supporting the thin plate portion 41 as shown in FIG.
And a pair of support walls 43, 43 fixed to the opposite ends of the thin plate 41 in the width direction (arrows A, B), respectively, and fixed to the thick plate 42. ing.

The thick plate portion 42 is a plate-like portion which is thicker than the thin plate portion 41, and the thin plate portion 41 is provided so as to extend on the center line of the distal end surface 42a.

The support walls 43, 43 have their wall surfaces 43a,
The thin plate portion 41 is joined so as to be orthogonal to both end surfaces in the width direction, and its base end surfaces 43b, 43b are joined to both end portions in the width direction of the distal end surface 42a of the thick plate portion 42. Also,
The support walls 43 are formed in a tapered shape from the base end to the front end. In the present embodiment, the thin plate portion 41, the thick plate portion 42, and the support wall portions 43 are integral members.

As shown in FIG. 2, the pair of slide dies 21 and 22 are arranged so that the concave wall surfaces 21a and 22a are opposed to both side surfaces 41b and 41b of the thin plate portion 41, respectively. Both sides 21b, 21 in the B direction
b, 22b, 22b are fitted by contacting the wall surfaces 43a, 43a of the pair of support wall portions 43, 43.

In the molding die 100 of the present embodiment, the core die 40 is configured as described above. Therefore, when the resin shutter 3 shown in FIG. 4 is to be injection molded, the core die shown in FIG. The thin plate portion 41 of the mold 40 is firmly supported by the support wall portions 43, 43 as compared with the related art.

Accordingly, as shown in FIG. 6, the molten resin is injected at a high pressure into the cavity 26a of the connecting portion 8 of the resin shutter 3 communicating with the cavities 26b and 26c of the pair of side walls 6 and 7, and the cavity 26a is discharged. Even when the high-pressure molten resin flows into the cavities 26b and 26c of the pair of side walls 6 and 7 through the thin plate 41 of the core mold 40 as shown in FIG. Deformation in the thickness direction (directions of arrows C and D) is prevented. Therefore, the thickness of the two side plates 6 and 7 can be made uniform. Thereby, the quality of the resin shutter 3 shown in FIG. 4 can be improved. In addition, since the adjustment work for equalizing the thickness of the side plate portions 6 and 7 can be reduced or omitted, the molding work can be simplified.

In the above embodiment, the molding die 100 for molding the resin shutter 3 having a U-shaped cross section has been described. However, for example, another molding die having a thin U-shaped cross section or a bent cross-sectional shape may be used. The present invention may be applied to the case of molding an arbitrary molded article, and may adjust the resin flow rate in the cavity. In addition, although the fixed mold 16 and the movable mold 50 are arranged vertically, the arrangement may be reversed, or alternatively, arranged left and right.

[0026]

As described above in detail, according to the resin shutter molding die of the first aspect, the pair of side plate portions formed in the gap between the thin plate portion of the core die and the pair of slide dies. Even when the molten resin is injected into the cavity with high pressure, the thin plate portion of the core mold is prevented from being deformed in the thickness direction by the pair of support walls. Therefore, the thickness of the two side plates connected by the connecting portion can be made uniform.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a core mold of a molding die of a resin shutter according to the present invention.

FIG. 2 is a plan view showing a joint state between a core mold and a slide mold in FIG. 1;

FIG. 3 is a front view showing an example of a magnetic disk.

FIG. 4 is a perspective view showing an example of a resin shutter.

FIG. 5 is a vertical sectional view showing a molding die for molding the resin shutter of FIG. 4;

FIG. 6 is an enlarged sectional view showing the molding die of FIG. 5;

FIG. 7 is a perspective view showing a core mold of the molding mold of FIG. 6;

[Explanation of symbols]

 Reference Signs List 3 resin shutter 6, 7 side plate portion 8 connecting portion 16 fixed die 21, 22 slide die 26, 26a, 26b, 26c cavity 27 gate 40 core die 41 thin plate portion 41a base end 42 thick plate portion 43 support wall portion 50 movable Mold 100 Mold

Claims (1)

(57) [Claims] 1. A molding die for integrally molding a resin shutter having a pair of U-shaped sections having a pair of opposed side plates and a connecting portion for connecting the side plates. A fixed mold having a cavity and having a gate communicating with the cavity, and a movable mold which is brought into contact with and separated from the fixed mold to form a pair of side plate cavities communicating with the cavity of the connecting portion. Along with the movable mold, a core mold disposed between the cavities of the side plate portion, and a core mold which is moved toward and away from the core mold in a direction intersecting with a direction of approaching and separating the movable mold. And a pair of slide dies forming a cavity of the side plate portion, wherein the core die extends to a thin plate portion disposed between the cavities of the pair of side plate portions and a base end of the thin plate portion. A thick plate portion which is located and supports the thin plate portion; A molding die for a resin shutter, comprising: a pair of support walls fixed to and opposed to both ends in the width direction of the thin plate, respectively, and fixed to the thick plate.