JPH06190873A - Die equipment for molding half case for floppy disk - Google Patents

Abstract

(57) [Summary] [Construction] The first resin gate 33 is provided on the side of the light protector holes 15 and 25 that is normally covered with a shutter, and outside the storage disk body storage units 18 and 28, and It is arranged on the engraved surface of the die 30 corresponding to the center of the half cases 10 and 20 as much as possible. Second resin gate 3
4 on the side of the write protector holes 15 and 25 of the portion to which the label is attached, and in addition, the storage disk body storage portion 1
It is arranged on the engraved surface of the mold 30 outside the parts 8 and 28 and as close to the center of the half cases 10 and 20 as possible. [Effect] The resin flow area from each gate is the same, there is no difference in the shrinkage ratio of the molded product, and there is no need to perform preform processing on the mold. The weld line also appears in a dispersed form without being concentrated at the final point, and not only is it strengthened in terms of strength, but it is also possible to perform degassing by gas vent processing by parting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die device for injecting a molten resin into a cavity in a mold to mold a half case for a floppy disk for accommodating a disk-shaped storage disk body. Regarding

[0002]

2. Description of the Related Art Conventionally, when molding a half case for a floppy disk for accommodating a disk-shaped storage disk body, a gate (resin injection port) is formed on the engraved surface of a mold corresponding to the four corners of the surface of the half case. ) Is provided, the molten resin is supplied to the cavity of the mold from these four gates to mold the half case. Therefore, the molten resin injected from the four gates flows toward the central portion of the half case.

FIG. 21 shows a half case for a floppy disk formed by the above-mentioned four-point gate. In the figure, 1 is a shutter (shown by a broken line), 2 is a shutter area where the shutter 1 is slidably mounted, 3 is a label area where a label is attached, 4a, 4b, 4c and 4d are resin injection marks. is there. However, when molding is performed with a four-point gate, especially in the upper case (see FIG. 21) where there is no through hole in the central part, degassing in the central part is likely to be insufficient, and a sagging surface occurs on the surface of the molded product. Alternatively, there is a problem that the molded product is warped because pressure is not uniformly applied to the molded product.

Therefore, in order to deal with the above problem, the gate of the molten resin to the cavity is usually covered with a shutter, outside the storage portion of the storage disk body, and at the center of the half case as much as possible. There is disclosed a technique of arranging two points on the engraved surface of a mold corresponding to the deviation and supplying a molten resin from the gate of these two points to a cavity of the mold to mold a half case (Japanese Patent Laid-Open No. 1-1999). 16692
No. 2).

FIG. 22 shows a half case of a floppy disk formed by the two-point gate. FIG. 3A is a plan view of the upper case, and FIG. 3B is a plan view of the lower case.
As is clear from the figure, the resin injection marks 4a and 4b are the shutter area 2 which is normally covered by the shutter 1 (shown by the broken line), and also outside the storage portion of the storage disk body.
Moreover, it remains as close to the center of the half case as possible.

[0006]

[Patent Document 1] Japanese Patent Application Laid-Open No. 1-16692
In the molding method using the two-point gate disclosed in Japanese Patent Publication No. 2, the resin can smoothly flow in the cavity and the gas can be discharged smoothly, and the molded product has defects such as sagging surface and warpage. Can be prevented. However, since the injection direction of the resin in the molding method using the above-mentioned two-point gate is only on the shutter side, the gas concentrates near the center line that longitudinally crosses the shutter area 2 and the label area 3 of the half case. The resin flow from the gate did not completely merge on the center line, and
As shown in (a) and (b), a weld line (we) is formed on the center line that vertically cuts the shutter area 2 and the label area 3.
ldline) WL occurs. Since the shutter area 2 is for mounting the shutter 1 and the label area 3 is a portion formed by thinning the thickness for attaching a label, the weld line WL is of a half case as described above. Shutter area 2 and label area 3
If it is located on the center line that runs through and, the strength of the molded product will be weakened.

Further, in the normal injection molding, the degassing is usually dealt with by subjecting the mold to a gas venting process, but as described above, the shutter area 2 of the half case is used.
In order to remove the gas concentrated on the center line that crosses the label area 3 and the label area section 3, the gas vent processing cannot handle it. For this reason, a slit-shaped block is attached to the engraved surface of the mold corresponding to the final point of the weld line WL in advance for degassing, which not only takes time to attach the block but also attaches the block of the molded product. Burrs were sometimes generated at the part corresponding to the joint part.

Further, since it is a two-point gate on the shutter side, the resin supply to the label area 3 is weak and a contraction difference between the shutter area 2 and the label area 3 occurs. It was necessary to perform preform processing such that the width of the engraving surface corresponding to the label area 3 of the mold was set to be wide in consideration of the difference in shrinkage. In view of the above, it is an object of the present invention to provide a mold device for molding a half case for a floppy disk, which can strengthen the strength of a molded product, can be degassed by a gas venting process, and does not require a preform process. .

[0009]

A means for solving the problems according to the present invention is to inject a molten resin into a cavity in a mold to form a half case for a floppy disk for accommodating a disk-shaped storage disk body. The first injection port for injecting the molten resin is on the side of the light protector portion that is normally covered by the shutter, and outside the storage portion of the storage disk body, and as much as possible. The second injection port for injecting the molten resin, which is arranged on the engraved surface of the mold corresponding to the center of the case, is on the light protector side of the part to which the label is attached, and moreover, the storage disk body. It is arranged on the engraved surface of the mold corresponding to the center of the half case as much as possible outside the storage part.

[0010]

With the arrangement of the injection ports of the above means for solving the problems, the resin flow areas from the respective injection ports are equal and there is no difference in the shrinkage rate of the molded product, and the length, width and corner area of the external dimension of the molded product are eliminated. Since there is little influence on the thickness of the shutter area and the thickness of the label area, it is not necessary to perform preform processing on the mold.

Further, since the weld line appears in a form of being dispersed without concentrating on the final point, not only is it strengthened in terms of strength, but also degassing is possible by gas vent processing by parting.

[0012]

EXAMPLES The present invention will be described in detail below based on examples. First, regarding the structure of the floppy disk, Fig. 1
This will be described in detail with reference to 8 and 19. 18A and 18B are views showing the upper case of the floppy disk. FIG. 18A is a plan view seen from the outside, and FIG. 18B is a plan view seen from the inside. 19A and 19B are views showing the lower case of the floppy disk, in which FIG. 19A is a plan view seen from the outside and FIG. 19B.
Is a plan view seen from the inside.

The floppy disk comprises a disk-shaped storage disk body (not shown) including an upper case 10 and a lower case 20.
To store and hold. As shown in FIG. 18, the upper case 10 is formed into a substantially square thin-walled surface, and a shutter area portion 12 on which a shutter 11 (shown by a broken line) is slidably mounted in the left-right direction is provided on the surface 10a side. ,
The label area portion 13 to which the label is attached and the label area portion 13 are each slightly recessed from the other portions. A rectangular magnetic head introduction window 14 is formed at the center of the shutter area 12. Further, a hole 15 for a light protector is formed outside the edge of the label area 13.

On the inner surface 10b side of the upper case 10,
An outer frame 16 is formed over substantially the entire outer edge portion,
Further, arc-shaped ribs 17 are formed so as to be continuous with the outer frame 16. As a result, the inside of the rib 17 serves as a disk body storage portion 18 for storing the storage disk body, and the rib 1
The outside of 7 and the upper right of FIG.
18A is a spring accommodating portion 19 for accommodating a spring (not shown) for urging the spring 1 to the right in FIG.

As shown in FIG. 19, the lower case 20 is formed in a substantially square thin-walled surface, and a circular through hole 21 is formed in the center thereof. On the front surface 20a side of the lower case 20, a shutter area portion 22 in which the shutter 11 is slidably mounted in the left-right direction and a label area portion 23 in which a label is attached are slightly recessed from other portions. It is provided in. A rectangular magnetic head introduction window 24 is formed at the center of the shutter area 22.
Are formed. A hole 25 for a light protector is formed outside the edge of the label area 23.

On the inner surface 20b side of the lower case 20,
An outer frame 26 is formed over almost the entire outer edge portion,
An arcuate rib 27 is formed so as to be continuous with the outer frame 26. As a result, the inside of the rib 27 serves as a disk body storage portion 28 for storing the storage disk body, and the rib 2
Shutter 1 is on the outside of 7 and in the upper left of FIG.
The spring accommodating portion 29 accommodates a spring (not shown) for urging 1 toward the left side in FIG.

A mold device for molding the upper case 10 and the lower case 20 of the floppy disk configured as described above will be described in detail with reference to the sectional view of FIG.
The molding die device includes a fixed die 30 having engraved surfaces for forming the surfaces 10a, 20a of the upper case 10 and the lower case 20, an inner surface 10b of the upper case 10 and the lower case 20,
And a movable mold 31 having an engraved surface for forming 20b.

The two injection ports (gates) 33 and 34 for injecting the molten resin into the cavity 32 formed between the fixed mold 30 and the movable mold 31 are provided in the fixed mold 30. It is placed at a predetermined position on the engraved surface. By the way, the 3.5-inch floppy disks commercially available today have a 4-point gate and a 2-point gate. The mold device for molding a half case for a floppy disk has recently been moved from a 4-point type to a 2-point gate type. This is because the 2-point gate has advantages over the 4-point gate in terms of cost, a large number of gates, and appearance. In terms of the size of the molded product, the standard is satisfied by applying the preform on the mold. Like this, 2
Although the number of point gate molding die apparatuses has been increasing, no matter which molding die apparatus is used and the arrangement is different, the gate positions are all two points on the shutter side. Certainly, if the gate position is placed on the shutter side, the resin injection marks will be invisible at the external appearance, which is good for customers. However, the molding apparatus for molding a two-point gate in which all gate positions are on the shutter side does not satisfy all of the mold manufacturing, moldability, and product function as described above.

Therefore, the applicant of the present invention can obtain what kind of molded product when molded with another gate, that is, one point on the shutter side and one point on the label side, and what is the difference from the molded product with two points on the shutter side. I tried molding with a possible 2-point gate. (Test content) Using the molding die apparatus having the four-point gates 1 to 3 shown in FIG. 17, the four-point gates were selectively used for molding. In FIG. 17, the gate is on the side of the holes 15 and 35 for the light protector in the portion of the shutter areas 12 and 22 that is covered by the normal shutter, and outside the storage portions 18 and 28 of the storage disk body, and The gates are arranged at positions corresponding to the centers of the half cases 10 and 20 as much as possible, and the gates are arranged at positions facing the gates with the magnetic head introduction windows 14 and 24 sandwiched between them, which are usually covered with a shutter. There is. The gate is on the side of the write protector holes 15 and 35 of the label area portions 13 and 23, and outside the storage portions 18 and 28 of the storage disk body, and as much as possible to the half cases 10 and 20.
The gate is located at a position corresponding to the center of
Shutter area parts 12 and 22 and label area part 1
It is arranged at a position facing the gate with a center line longitudinally crossing between the gate electrodes 3 and 23 interposed therebetween. Gate selection method (2-point gate) (shutter side gate) (label side gate) Example 1 Gate NO. Gate NO. Comparative Example 1 Gate NO. Gate NO. Comparative Example 2 Gate NO. Gate NO. Comparative Example 3 Gate NO. Gate NO. (1 point gate) (Shutter side gate) (Label side gate) Comparative Example 4 Gate NO. -Comparative Example 5 Gate NO. FIG. 1 shows a gate position corresponding to Example 1, FIG. 2 shows Comparative Example 1, FIG. 3 shows Comparative Example 2, FIG. 4 shows Comparative Example 3, FIG. 5 shows Comparative Example 4, and FIG. ing. Molding conditions (filling speed (sec)) (holding pressure (kg / cm ² )) Condition NO. 1 0.6 660 Condition NO. 2 0.6 440 Condition NO. 3 0.6 880 Condition NO. 4 0.4 660 Condition NO. 5 0.5 660 Condition NO. 6 0.5 440 Equipment used Molding machine: Sumitomo SYCAP SG-1500 MIII Temperature controller: SYSKO TURBU TD-U4-341 Resin: TORAY ABS 500X11 GRAY Hot runner: Century AMC Mold: 2 sets 4 point gate MFD Above gate A half case for a floppy disk was molded using the selection method, molding conditions, and equipment used, and the results of measuring the outer dimension length, width, and thickness of each corner area, shutter area, and label area were displayed. Shown in 1.

The thicknesses of the corner area, shutter area and label area of the molded product were measured at the measurement positions shown in FIGS. Measurement position Corner area thickness of molded product: P1 to P4 Shutter area thickness of molded product: P5, P6 Label area thickness of molded product: P7, P8

[0021]

[Table 1]

In the table, ◯ indicates that the outer dimension length and width of the molded product and the thicknesses of the corner area portion, the shutter area portion and the label area portion are within the tolerance, and x indicates the outer dimension of the molded product. It indicates that the dimensional length, width, and thickness of the corner area, shutter area, and label area are out of tolerance. The tolerances of the outer length and width of the molded product and the thicknesses of the corner area, shutter area and label area are shown below.

External dimension length tolerance of molded product: 93.93 ± 0.17 mm External dimension width tolerance of molded product: 90.15 ± 0.15 mm Corner area thickness tolerance: 1.65 ± 0.05 mm Shutter Area thickness tolerance: 1.355 ± 0.025
mm Label Area Thickness Tolerance: 1.45 ± 0.05 mm As is clear from Table 1, when Example 1 and Comparative Example 1 are compared, Comparative Example 1 has a dimension outside the tolerance as compared with Example 1. It was found that there are many places where the shrinkage occurs, and the shrinkage difference between the shutter area portions 12 and 22 and the label area portions 13 and 23 is large. That is, if the gate position is set to the condition of the first embodiment,
The shrinkage difference is small, and the mold size correction is small. Similarly, when Comparative Example 2 and Comparative Example 3 are compared, Comparative Example 2 has more dimensions than the Comparative Example 3 than the tolerance, and if the gate position is set to the conditions of Comparative Example 3, It was found that there is little difference in shrinkage and less modification of mold dimensions is required. Then, comparing Example 1 and Comparative Example 3, there was no great difference in product dimensions. In Comparative Examples 4 and 5, the resin was not completely filled, and the shutter area portion was significantly deformed (warped), which made measurement impossible.

That is, when the gate position is set to the conditions of Example 1 and Comparative Example 3, the resin flow areas from the gate are equal, and there is no difference in the shrinkage ratio of the molded product. Therefore, it is not necessary to preform the mold. In addition, the weld line (wel) of Example 1 and Comparative Examples 1 to 3 was used.
The position of d line) was also confirmed. 9 to 1
2 shows the positions of the weld lines in Example 1 and Comparative Examples 1 to 3. FIG. 9 shows Example 1, FIG. 10 shows Comparative Example 1, and FIG.
Corresponds to Comparative Example 2, and FIG. 12 corresponds to Comparative Example 3, respectively.

As is apparent from the figure, when molding is performed with one point on the shutter side and one point on the label side as in Example 1 and Comparative Examples 1 to 3, when molding is performed using the conventional two-point gate on the shutter side. As described above, it was found that the weld line WL does not appear on the center line that crosses the shutter area portions 12 and 22 and the label area portions 13 and 23, but appears in a dispersed form without being concentrated at the final point. Therefore, in the case of molding with one point on the shutter side and one point on the label side, the gas is generated in the shutter area portions 12 and 22 and the label area portions 13 and 23.
Instead of concentrating on the center line that runs through and, it is possible to support degassing by gas venting processing by parting.

However, in Comparative Examples 2 and 3, FIG.
Like 1 and 12, the weld line WL has a wall thickness of about 1.3.
Since it appears in the form of traversing the thin shutter areas 12 and 22 of 35 mm, the strength of the shutter areas 12 and 22 becomes weak. In addition, the weld line WL may appear near the reference hole 50 and a crack may occur in the reference hole 50.

That is, if the gate position is set to the condition of Example 1 or Comparative Example 2, the weld line WL crosses the shutter area portions 12 and 22, as shown in FIGS.
Moreover, since it does not appear in the vicinity of the reference hole 50, the strength of the shutter area portions 12 and 22 is increased, and moreover, cracks do not occur in the reference hole 50. Furthermore, from the gate positions of Examples 1 to 4 and Comparative Examples 1 to 3 described above, the filling rate was 9
The resin was injected at 5%, and it was examined how the positions where the resins from the two gates finally fuse, that is, the so-called short shot positions appear. 13 to 14 show the short shot positions of Example 1 and Comparative Examples 1 to 3. 13 corresponds to Example 1, FIG. 14 corresponds to Comparative Example 1, FIG. 15 corresponds to Comparative Example 2, and FIG. 16 corresponds to Comparative Example 3.

First, comparing Example 1 with Comparative Example 1, as is apparent from FIGS. 13 and 14, in Comparative Example 1, the short shot position SS is the hole 1 for the light protector.
It was found that the short shot position SS does not appear in the light protector portion in Example 1, while it appears around 5,25 (hereinafter referred to as the light protector portion). That is, with respect to the strength of the light protector portion, Example 1 is stronger than Comparative Example 1. Next, comparing Comparative Example 2 and Comparative Example 3, as seen from FIGS. 15 and 16, in Comparative Example 2, the short shot position S
S appears in the light protector portion, while Comparative Example 3
However, since the short shot position SS does not appear in the light protector portion, the strength of the light protector portion is higher in Comparative Example 3 than in Comparative Example 2. And Example 1
13 and 16, when the short shot position SS does not appear in the vicinity of the reference hole 50 in the first embodiment, as shown in FIGS. 13 and 16, the short shot position SS in the third comparative example. Appears in the vicinity of the reference hole 50, so that in Comparative Example 3, a crack may occur in the reference hole 50.

That is, if the gate position is set to the condition of the first embodiment, the short shot position SS does not appear near the light protector portion and the reference hole 50 as shown in FIG. 13, so that the strength of the light protector portion becomes strong, Moreover, cracks do not occur in the reference hole 50. Comprehensive determination From the above, the gate position of the conditions of the first embodiment, that is, as shown in FIG. 1, the first resin gate 33 is normally covered with the shutter on the light protector holes 15 and 25 side, Moreover, the storage disk storage unit 18,
The second resin gate 34 is arranged on the engraved surface of the mold 30 outside of 28 and as close to the center of the half cases 10 and 20 as possible, and the second resin gate 34 is provided in the hole 15 for the light protector of the portion to which the label is attached. 25 side, and outside the storage disk body storage portions 18, 28, and as much as possible to the half case 10,
If it is arranged on the engraved surface of the mold 30 corresponding to the center of 20, the strength of the molded product can be strengthened, and gas venting can be used for degassing, and preforming is not required. Therefore, the number of man-hours required for mold production is reduced, which leads to cost reduction.

The present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

[0031]

As is apparent from the above description, according to the present invention, the strength of the molded product can be strengthened, the gas venting treatment is sufficient for degassing, and the preform processing is not required. It has the excellent effect of reducing man-hours and reducing costs.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a gate position of a molding die device for a half case for a floppy disk according to a first embodiment.

FIG. 2 is a view showing a gate position of a molding die device of a half case for a floppy disk according to Comparative Example 1.

FIG. 3 is a diagram showing a gate position of a molding die device of a half case for a floppy disk according to Comparative Example 2.

FIG. 4 is a diagram showing a gate position of a molding die device for a half case for a floppy disk according to Comparative Example 3;

FIG. 5 is a view showing a gate position of a molding die device of a half case for a floppy disk according to Comparative Example 4.

FIG. 6 is a diagram showing a gate position of a molding die device of a half case for a floppy disk according to Comparative Example 5.

FIG. 7 is a diagram showing measurement positions of respective thicknesses of a corner area portion, a shutter area portion, and a label area portion of the upper case.

FIG. 8 is a diagram showing measurement positions of respective thicknesses of a corner area portion, a shutter area portion, and a label area portion of the lower case.

FIG. 9 is a diagram showing positions of weld lines in the first embodiment.

10 is a diagram showing the position of a weld line in Comparative Example 1. FIG.

11 is a diagram showing positions of weld lines in Comparative Example 2. FIG.

12 is a diagram showing positions of weld lines in Comparative Example 3. FIG.

FIG. 13 is a diagram showing a short shot position in the first embodiment.

14 is a diagram showing a short shot position in Comparative Example 1. FIG.

15 is a diagram showing a short shot position in Comparative Example 2. FIG.

16 is a diagram showing a short shot position in Comparative Example 3. FIG.

FIG. 17 is a diagram showing the positions of gates selected in the present molding test.

FIG. 18 is a plan view of an upper case for a floppy disk.

FIG. 19 is a plan view of a lower case for a floppy disk.

FIG. 20 is a cross-sectional view of a mold device for molding a half case for a floppy disk.

FIG. 21 is a plan view of a conventional half case for a floppy disk formed by a 4-point gate.

FIG. 22 is a plan view of a conventional half case for a floppy disk formed by a shutter-side two-point gate.

[Explanation of symbols]

 10 Upper Case 11 Shutters 12,22 Shutter Area 13,23 Label Area 15,25 Light Protector Hole 18,28 Disk Storage 20 Lower Case 30 Fixed Mold 31 Movable Mold 32 Cavity 33,34 Gate

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B29L 31:34 4F

Claims (1)

[Claims] 1. A method for injecting a molten resin into a cavity in a mold to form a half case for a floppy disk for accommodating a disk-shaped memory disk body, wherein the molten resin is injected. The first inlet for this is on the side of the light protector that is normally covered by the shutter, outside the storage of the storage disk, and as close as possible to the center of the half case. The second inlet for injecting the molten resin is located on the side of the light protector where the label is attached,
Moreover, the mold device for molding a half case for a floppy disk, which is arranged on the engraved surface of the mold corresponding to the center of the half case as much as possible outside the storage part of the storage disk body.