JP3094404B2 - Mold for half-molding of floppy disk case - 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 forming a case half of a floppy disk, and more particularly to a mold for forming a case half of a floppy disk which provides a case half with a small thickness of a disk guide rib near a shutter portion. About the type.

[0002]

2. Description of the Related Art A micro floppy disk is formed by rotatably storing a disk-shaped record carrier in a diskette formed by connecting a thin upper diskette half and a lower diskette half as a case half. Each of these diskette halves is a resin molded product. 4 to 7 are plan views showing the lower diskette half and the upper diskette half. The lower diskette half 1 has a substantially rectangular flat plate shape, and a frame wall 2 is formed at a peripheral portion. On the inner surface of the lower diskette half 1, a shallow circular concave recording carrier storage section 3 is formed. A plurality of arc-shaped disk guide ribs 4 are formed at the periphery of the record carrier housing 3 so as to project therefrom. A central portion of the record carrier housing 3 has a circular shape into which a hub of the record carrier is fitted. Opening hole 5 is formed. At the same time, an opening window 6 for introducing a head is formed in the center of the front part of the lower diskette half 1 and is located in the recording carrier storage part 3. Further, the record carrier accommodating section 3 is formed with an L-shaped lifter positioning projection 7, a lifter lifting projection 8, and a pair of lifter receiving projections 9. These ridges 7, 8 and 9 are arranged in the order described above with respect to the direction of rotation of the record carrier. At the same time, the lifter receiving ridges 9 extend in a tangential direction of a circle concentric with the record carrier accommodating section 3, and are provided with lifter lifting ridges 8.
Has a direction perpendicular to the lifter receiving ridge 9. On the inner surface of the lower diskette half 1, fixing bosses 10, 11, 12, 13 and positioning bosses 14, 15, 16 are protrudingly formed at four corners located outside the record carrier storage portion 3, respectively. ing. Further, at a front portion of the lower diskette half 1, a shutter mounting portion 17 for mounting a shutter (not shown) for opening and closing the opening window 6;
A spring built-in portion 18 for urging the shutter in the closing direction is formed. The lower diskette half 1
A write protector mounting portion 19 for mounting a write protector (not shown) is formed at one corner of the rear portion, and an opening 20 for discriminating the storage capacity of a floppy disk is formed at the other corner. Have been. The outer surface of the lower diskette half 1 has a shutter mounting surface.
A concave portion 21 is formed on the front portion, and a label surface 22 is formed on the rear end side. Further, a groove 17A for sliding the shutter for opening and closing the opening window 6 is formed in the front part of the shutter assembly 17 so as to penetrate the plate material. Note that 2
3 and 24 are gate marks on the lower diskette half 1. The gate traces 23 and 24 are always hidden by the shutter. 25 is a trace of gas release.

On the other hand, the upper diskette half 31 also has a substantially rectangular flat plate shape, and a frame wall 32 is formed at a peripheral portion. The inner surface of the upper diskette half 31 is formed with a shallow circular concave recording carrier storage portion 33. A plurality of arc-shaped disk guide ribs 34 are formed at the periphery of the record carrier storage portion 33 so as to protrude therefrom.
At the center of 33, an annular projection 35 is formed in which the hub of the record carrier is fitted. At the same time, an opening window 36 for head introduction is formed in the center of the front part of the upper diskette half 31 at the position above the recording carrier storage part 33. Further, a plurality of lifter receiving ridges 37 are formed in the record carrier accommodating portion 33 at positions corresponding to the lifter receiving ridges 9 of the lower diskette half 1. In addition, fixing bosses 38, 39, 40, 41 and positioning bosses 42, 43, 44 are formed on the inner surface of the upper diskette half 31 at four corners located outside the record carrier accommodating portion 33, respectively. ing. Further, at the front of the upper diskette half 31, there are formed a shutter mounting portion 45 for mounting a shutter (not shown) for opening and closing the opening window 36, and a spring mounting portion 46 for urging the shutter in the closing direction. ing. A write protector mounting portion 47 for mounting a write protector (not shown) is formed at one corner of the rear portion of the upper diskette half 31, and the storage capacity of the floppy disk is formed at the other corner. Opening for identification 48
Are formed. Also, the upper diskette half 31
On the outer surface, a shutter assembly 49 is formed at the front, and a label surface 50 is formed at the rear thereof in a concave shape.
In addition, 51 and 52 are gate marks on the upper diskette half 31. The gate traces 51 and 52 are always hidden by the shutter. Also, 53 and 54 are traces of gas release.

FIGS. 8 and 9 show an example of a molding die for forming the lower diskette half 1 of such a micro floppy disk. FIG. 8 is a sectional view of the lower diskette half 1 taken along the line AA in FIG. 4, and FIG.
It is an enlarged view which shows the core member which forms the B part of middle lower diskette half 1. 8 and 9, reference numeral 61 denotes a cavity member serving as a first mold, 62 denotes a core member serving as a second mold, and the cavity member 61 and the core member 62 as mold members are arranged in a vertical direction in FIG. The cavity 63 which is opened and closed to form the lower diskette half 1
Is formed inside. In particular, the cavity member 61
Are formed on the outer surface of the lower diskette half 1, and the core member 62 is formed on the inner surface of the lower diskette half 1. In the cavity member 61, two resin passages 64 and 65 are formed for one cavity 63. These resin passages 64 and 65 are connected to spears 66 and 66, respectively.
67, with a direct gate 6
8, 69 open to the cavity 63 in the thickness direction of the lower diskette half 1. And both gates 68, 69
Both front corners 23 outside the record carrier storage 3,
It opens to the position corresponding to 24. The core member 62 has a substantially hemispherical recess 62 directly below the direct gates 68 and 69.
A is formed. A plurality of degassing nests (not shown) are fixed, thereby forming a degassing slit corresponding to the degassing mark 25 at the rear of the recording carrier storage part 3 in the cavity 63. Reference numeral 70 denotes a concave portion for forming the disk guide rib 4, and a gate 6
It is formed close to 8,69. Reference numeral 71 denotes a projection for forming the opening window 6. In addition, upper diskette half 31
Has basically the same structure.

[0005]

In the mold for molding the lower diskette half 1 of this micro floppy disk, the recording carrier storage portion 3 of the lower diskette half 1 is used.
The lower diskette half 1 is opened in the thickness direction of the lower diskette half 1 at a position corresponding to both front corners outside the gate 6.
8 and 69 are arranged, so lower diskette half 1
On the inner surface side, bulging portions 23 and 24 as gate marks are formed due to the substantially hemispherical protruding portion 62A.
Due to the influence of 24, the plate thickness of the disk guide rib 4 in the vicinity is likely to increase. Since the gate traces 23 and 24 are covered by the shutter from the outer surface side, the disc guide ribs 4
When the thickness of the shutter is large, there is a problem that the shutter cannot be opened and closed smoothly. Also, if the plate thickness of the disc guide rib 4 is too thin, there is a problem that the shutter is likely to come off this time. As described above, strict control of the thickness of the shutter portion is required. For example, in the case of the standard size of the thickness of the disc guide rib 4 of 1.33 mm, about ± 0.025 mm
Is within the allowable range, and its manufacture is extremely difficult.

In addition, in the case of the lower diskette half 1, a groove 17B for sliding the shutter for opening and closing the opening window 6 is formed in the front part of the outer surface of the lower diskette half 1 by penetrating the plate material at the shutter assembly part 17. The portion C in front of the groove 17B has a problem that the mechanical strength is not sufficient. In addition, since the space between the mold cavities 63 in the groove 17B is extremely small, the resin is difficult to fill in the portion C in front of the groove 17B. If the mechanical strength at a location forward of the groove 17B is low, there is a problem that the locking strength of the shutter at the time of falling is not sufficient. There is also a problem that this portion is easily damaged. Therefore, it is conceivable to design the plate in a portion thicker than the groove 17B so as to have a predetermined plate thickness. However, in this case, the disk guide rib 4 near the bulging portions 23 and 24 described above may be designed. There is a problem that the tendency of the plate thickness to become thicker becomes more prominent. In addition, by performing electrical discharge machining, etc.
It is conceivable to adjust the thickness in μm units. However, since the electric discharge machining process is extremely complicated, a diskette half of a floppy disk, particularly a lower diskette half 1, whose thickness can be easily controlled without performing electric discharge machining is provided. A mold is desired.

The present invention has been made based on the above problems, and an object of the present invention is to provide a mold for molding a case half of a floppy disk in which the thickness of a shutter portion of a diskette half of a floppy disk can be easily controlled. Aim. Another object of the present invention is to provide a mold for molding a case half of a floppy disk, in which the thickness of a portion in front of the groove for shutter slide on the outer surface of the lower diskette half can be easily controlled.

[0008]

According to a first aspect of the present invention, there is provided a mold for molding a case half of a floppy disk, comprising: a recording carrier accommodating portion having a substantially rectangular flat shape and a shallow circular concave shape on an inner surface; A mold half for forming a case half of a floppy disk having an arc-shaped disk guide rib protruding from a peripheral edge of the case half, wherein the mold includes a first mold forming an outer surface of the case half, and an inner surface. And a second mold forming the case half, the first mold having an opening in a thickness direction of the case half at a position close to the disk guide rib at both corners at a front portion of the recording carrier accommodating portion. The second mold has a recess forming the disc guide rib, and the recess adjacent to the gate has a shallow bottom portion in which the depth of the recess is smoothly reduced. Things.

In the mold for molding a case half of a floppy disk according to a second aspect of the present invention, the shallow portion has a maximum of 20 to
This is a decrease of 30 μm.

[0010]

In the mold for forming a case half of a floppy disk according to claim 1, the depth of a concave portion of the mold forming a disk guide rib close to the gate is smoothly reduced near the gate. Therefore, the disk guide rib does not become thick, and the disk guide rib is substantially restored by the shallow portion to form a substantially flat surface.

In the mold for molding a case half of a floppy disk according to the present invention, the shallow bottom portion may have a maximum height of 20 mm.
Since the thickness of the disk guide rib is reduced by about 30 μm, the thickness of the disk guide rib near the gate can be more accurately defined, and the disk guide rib can be restored more flat.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to FIGS. FIG. 1 is a sectional view showing a molding die according to a first embodiment of the present invention for forming a lower diskette half 1 which is one case half of a floppy disk, and is a sectional view taken along line AA in FIG. FIG. 2 is an enlarged view of a core member forming part B in FIG. Since the mold of this embodiment has almost the same structure as that of FIGS. 8 and 9 described above, the corresponding parts are denoted by the same reference numerals, and the description thereof will be omitted. In the mold according to the present embodiment, the shallow portion 70 that is smoothly reduced in a substantially half-moon shape with the position closest to the gate 68 as the apex in the concave portion 70 for forming the disk guide rib 4.
A is formed. For this reason, the resin injected from the gate 68 is stored in the substantially hemispherical concave portion 62A and then intensively flows into the adjacent concave portion 70, but the shallow bottom portion 70A
Thereby, the error in the thickness direction can be greatly reduced. In addition, the disk guide rib 4 hardly loses due to the shallow bottom portion 70A, but is substantially restored by the inflow of the resin, and becomes a substantially flat surface. In particular, it is preferable that the maximum reduction amount t of the shallow portion 70A is 20 to 30 μm. By setting the maximum reduction amount t within the above range, the thickness of the disk guide rib 4 near the gate 68 can be more accurately defined, and the disk guide rib 4 can be made flatter. In FIG. 2A, the shallow bottom portion 70A is shown in a net shape for convenience of explanation. In this embodiment, only the lower diskette half 1 has been described, but the present invention can be similarly applied to the upper diskette half 31. It is particularly suitable for the lower diskette half 1. As shown in FIG. 5, the lower diskette half 1 has a shutter mounting surface 21 for mounting a shutter, and a groove 17A serving as a slide groove of the shutter in front of the opening window on the outer surface. The portion C in front of the groove 17A tends to be thin. For this reason, it is desirable that the cavity member 61 or the core member 62 be partially thinned so that the cavity 63 is partially thickened so that the thickness at the portion C becomes a predetermined value. The thickness of the disk guide rib tends to be further increased. However, by using the mold of this embodiment, the disk guide rib 4 does not become thick near the gate marks 23 and 24 even if the thickness of the portion C in front of the groove 17A is partially increased. .

Next, a mold device for molding a case half of a floppy disk incorporating the mold of this embodiment will be described with reference to FIG. 101 is fixed type, 102
Is a movable mold, and the fixed mold 101 and the movable mold 102 move up and down with respect to each other in the figure to open and close, and form a cavity 63 in the shape of the lower diskette half 1 or the upper diskette half 31 therebetween during mold clamping. However, in the present mold apparatus, the lower diskette half 1 and the upper diskette half 31 are formed simultaneously. In FIG.
The cavity 63 on the right side in the figure is for the upper diskette half 31, and the cavity 63 on the left side in the figure is for the lower diskette half 1. Hereinafter, a portion between the fixed die 101 and the movable die 102 is referred to as a first parting line PL1.
The fixed mold 101 has a fixed mold plate 103 and a fixed mold plate.
A first fixed-side receiving plate 104 attached to the back surface (upper surface in the figure) of the first fixed-side receiving plate 103; a second fixed-side receiving plate 105 attached to the back surface of the first fixed-side receiving plate 104; Fixed side receiving plate 10
5, a fixed-side mounting plate 107 mounted via a spacer block 106 to the fixed-side platen of the injection molding machine, the second fixed-side receiving plate 105 and the fixed-side mounting plate 10
7 and a manifold 108 disposed between the first and second manifolds. The fixed mold plate 103 is formed by fitting a cavity member 61 forming an outer surface of the lower diskette half 1 or the upper diskette half 31 into a frame plate 109. These cavity members 61 are fixed to the first fixed-side receiving plate 104 by bolts 110 from between the two fixed-side receiving plates 104 and 106 (hereinafter, referred to as a second parting line PL2). The second fixed-side receiving plate 105 is moved from the second parting line PL2 to the spacer block 106 by bolts 111.
It is fixed to. Further, the fixed side mounting plate 107 is fixed to the spacer block 1 by bolts 112 from outside (upper side in the figure).
Fixed to 06. Further, a plurality of spacers 113 and 114 are interposed between the fixed-side mounting plate 107 and the second fixed-side receiving plate 105 and the manifold 108. Note that the manifold 109 has a built-in heater 115.

A locating ring 116 is fixed to the outer surface of the fixed-side mounting plate 107, and a sprue bush 117 is fixed to the inner side of the locating ring 116 so as to penetrate therethrough. This sprue bush
The lower end of the drawing 117 is connected to the manifold 108. A runner communicating with a sprue 118 in the sprue bush 117 is provided in the manifold 108.
119 are formed. Spears 66 and 67 are connected to the lower side of the manifold 108. That is, through-holes 120 are formed in the cavity members 61 of the fixed-side receiving plates 104, 105 and the fixed-side mold plate 103, and spears 66, 67 built in spear bushes 121 embedded in the through-holes 120. Is joined to the lower surface of the manifold 108 at the outlet of the runner 119.
The inside of the through hole 120 is a runner of the manifold 108.
The lower end is opened to the cavity 63 as gates 68 and 69. The upper end of the spear bush 121 has a flange portion 122 for supporting the spears 66 and 67 from below in the figure. The flange portion 122 is located on the second fixed-side receiving plate 105 and has a through hole 120.
The lower end of the drawing is in contact with the upward step surface 123 formed in
Is in contact with the upwardly-facing stepped surface 124 formed at the bottom.

On the other hand, the movable mold 102 has a movable mold plate 130.
And a movable-side receiving plate 131 attached to the back (lower side in the figure) of the movable-side mold plate 130; and a movable-side of the injection molding machine attached to the back of the movable-side receiving plate 131 via a spacer block 132 and a support 133. And a movable side mounting plate 134 mounted on the side platen. The movable mold plate 130 includes a core member 62 which forms the inner surfaces of the lower diskette half 1 and the upper diskette half 31 in the frame plate 135, and these core members 62.
Are fitted with a base plate 136 that supports the plate from below. The base plate 136 is fixed to the core member 62 with bolts 137. The movable receiving plate 131 is fixed to the base plate 136 by bolts 138. Furthermore, the movable side mounting plate 13
4 is fixed to the movable-side receiving plate 131 by bolts 139 penetrating the spacer block 132 and the support block 133. The movable-side receiving plate 131 and the movable-side mounting plate 134
The protruding plates 140, 141 are relatively supported vertically between them. These protruding plates 140, 141
Are fixed to each other by bolts 142. And
A protruding pin 143 is fixed to the protruding plates 140, 141. These protruding pins 143 are
The movable side mold plate 130 is slidably penetrated in the vertical direction in the figure, and the front end faces the cavity 63. A return pin 144 is also fixed to the protruding plates 140, 141. The return pin 144 slidably penetrates the movable-side receiving plate 131 and the frame plate 135 of the movable-side mold plate 130, and the tip thereof faces the first parting line PL1. On the other hand, on the frame plate 109 of the fixed mold 101, a return pin
145 is fixed. Also, the springs 146 wound around the return pins 144 cause the protruding plates 140, 141
Is biased downward with respect to the movable-side receiving plate 131 in the figure.
Further, on the lower surface of the protruding plate 141, a protruding rod receiver 147 is fixed.
Penetrates the movable-side mounting plate 134. A guide pin 148 is fixed to the frame plate 109 of the fixed die 101, while a guide bush 149 into which the guide pin 148 is removably inserted is fixed to the frame plate 135 of the movable die 102. Have been.

Next, the operation of the above configuration will be described.
At the time of molding, the fixed mounting plate 107 is mounted on the fixed platen of the injection molding machine, the movable mounting plate 134 is mounted on the movable platen of the injection molding machine, and the nozzle of the injection molding machine is connected to the sprue bush 117. Then, fixed 10
After clamping the mold 1 and the movable mold 102, the molten resin is injected from the nozzle of the injection molding machine. This resin is supplied from sprue 118 to manifold 108, runner 119, spear bush.
The air flows into the cavity 63 from the gates 68 and 69 in order through the inside 121 and the through hole 120 of the cavity member 61. Then, the shapes of the lower diskette half 1 and the upper diskette half 31 are formed. At this time, the gates 68 and 69 are opened at positions corresponding to the two front corners of the diskette halves 1 and 31 on the outside of the record carrier storage portion 3. Since a substantially hemispherical concave portion 62A is formed immediately below 69, substantially hemispherical bulging portions 23 and 24 are formed in both diskette halves 1 and 31, respectively. The thickness of the disk guide ribs in the vicinity tends to increase. However, in the present embodiment, the depth of the concave portion 70 for forming the disk guide rib 4 close to the bulging portions 23, 24 is determined by setting the position closest to the bulging portions 23, 24 to the vertex. The resin injected from the gates 68, 69 is stored in the gate traces 23, 24 formed in a substantially hemispherical shape, and then formed adjacently, since the shallow bottom portion 70A is smoothly reduced in a substantially half-moon shape. , But the error in the thickness direction is significantly small. In addition, in the disk guide rib 4, the above-mentioned shallow bottom 70
A drop hardly occurs due to A, and the flow is substantially restored by the inflow of the resin, and a substantially flat surface is obtained. In particular, by setting the maximum reduction amount t of the concave portion 70 in the depth direction due to the shallow bottom portion 70A to 20 to 30 μm, for example, an error in the thickness of the disk guide rib of 1.33 mm can be made within a range of ± 0.025 mm. In addition, the disk guide rib 4 can be more accurately restored to the flat state. In particular, in the case of the lower diskette half 1, a shutter mounting surface 21 for mounting a shutter, and a groove as a slide groove of the shutter in front of the opening window on the outer surface.
17A is formed, and the mechanical strength is likely to be reduced in the portion C in front of the groove 17A. As a countermeasure against this, the cavity member is adjusted so that the thickness in this part becomes the specified one.
61 or the core member 62 is partially thinned and the cavity 63
Even if the part is thickened, the bulging part 23, 23
This is preferable because the plate thickness of the disk guide rib 4 near 24 does not greatly increase. When the resin is filled into the cavity 63 in this way, the fixed mold 101 and the movable mold 102 are opened after the filled resin is solidified. At this time,
The molded diskette halves 1 and 31 are fixed 101 first.
Then, the ejection rod of the injection molding machine pushes the ejection rod receiver 147 of the ejection plates 140 and 141, so that the ejection plate 140,
The diskette halves 1 and 31 are protruded by the protruding pins 143 which rise together with the protruding plates 140 and 141, and are separated from the movable mold 102. Thereafter, the mold is closed again. By repeating the above molding cycle, the upper and lower diskette halves 1 and 31 can be manufactured continuously.

As described above in detail, the mold half for molding the case half of the floppy disk according to the first embodiment has a substantially rectangular flat shape and a shallow circular concave recording carrier storage portion 3 on the inner surface.
33, arc-shaped disk guide ribs 4 and 34 protruding from the periphery of the record carrier storage sections 3 and 33, and an opening window for head introduction formed at the front center of the record carrier storage sections 3 and 33. A mold half for forming the lower diskette half 1 or the upper diskette half as a case half of the floppy disk having the diskette halves 6 and 36, wherein the first metal forming the outer surface of the lower diskette half 1 or the upper diskette half 1 and 31 is formed. A cavity member 61 serving as a mold, and a core member 62 serving as a second mold forming an inner surface, wherein the cavity member 61 is close to the disk guide ribs 4 and 34 in front of the outside of the recording carrier storage sections 3 and 33. Gates 68 and 69 which are opened in the thickness direction of the diskette half at positions where the core member 62
The recesses 70 forming the disc guide ribs 4 and 34 and the shallow bottom portions 70A in which the recesses 70 formed in the recesses 70 close to the gate have smoothly reduced depths are used. Even if the resin spreads in the thickness direction of the disc guide rib 4 due to the influence, the error in the thickness direction can be greatly reduced. Moreover, the disk guide ribs 4, 34 have a substantially flat surface with the shallow portion being substantially restored. In particular, the maximum reduction amount t of the shallow bottom portion 70A of the concave portion 70 of the core member 62 is set to 20 to 30.
By setting the thickness to μm, the thickness of the disk guide ribs 4 in the vicinity of the gate traces 23 and 24 can be more accurately defined, and the disk guide ribs can be restored to a flatter shape. Further, even if the portion C in front of the slide groove 17B of the shutter of the lower diskette half 1 is thickened, the plate thickness near the gate does not increase.

Although the present invention has been described with reference to the accompanying drawings, the present invention is not limited to this, and can be appropriately modified within the scope of the present invention. For example, in the above embodiment, two gates are provided for one diskette half, but one gate may be provided in some cases. In the above embodiment, for convenience of explanation, the case where the upper and lower diskette halves 1 and 31 are formed has been described. However, the upper and lower diskette halves 1 and 31 are divided into three or more rows by the runner portion. It is possible to form a plurality of pieces, such as molding one by one or six pieces.

[0019]

According to the first aspect of the present invention, there is provided a mold for half-forming a case of a floppy disk, wherein the recording carrier accommodating portion has a substantially rectangular flat shape and a shallow circular concave shape on the inner surface, and protrudes from the periphery of the recording carrier accommodating portion. A mold half for forming a case half of a floppy disk having a circular arc-shaped disk guide rib, the mold including a first mold forming an outer surface of the case half, and a second mold forming an inner surface of the case half. Wherein the first mold has a gate which is opened in the thickness direction of the case half at a position close to the disk guide rib at both front corners of the record carrier accommodating portion. The second mold has a concave portion forming the disk guide rib, and the concave portion close to the gate has a shallow portion in which the depth of the concave portion is smoothly reduced. Due to the gate trace In the thickness direction of the disk guide ribs also spreads out the resin, without the disc guide rib is thick,
The disk guide ribs are substantially restored at the shallow portion and become substantially flat.

In the case half mold for a floppy disk according to the second aspect of the present invention, since the shallow portion is reduced by 20 to 30 μm at the maximum position, the thickness of the plate near the gate can be more accurately determined. And the disk guide ribs can be made flatter.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of a mold for half-forming a case of a floppy disk according to a first embodiment of the present invention.

FIG. 2 is an enlarged view showing a core member of a mold for half-molding a floppy disk according to the first embodiment.
(a) is a plan view, and (b) is a sectional view taken along line DD of (a).

FIG. 3 is a cross-sectional view showing a mold device incorporating the case half-molding mold according to the first embodiment.

FIG. 4 is a plan view showing an inner surface of a lower diskette half.

FIG. 5 is a plan view showing the outer surface of a lower diskette half.

FIG. 6 is a plan view showing the inner surface of the upper diskette half.

FIG. 7 is a plan view showing the outer surface of the upper diskette half.

FIG. 8 is a sectional view of a main part showing a conventional mold for half-molding a floppy disk.

9A and 9B are enlarged views showing a core member of a mold for half-molding a case of a floppy disk according to the conventional example, wherein FIG. 9A is a plan view, and FIG. 9B is a sectional view taken along line DD of FIG. Show.

[Explanation of symbols]

 1 Lower diskette half (case half) 3,33 Record carrier storage part 4,34 Disk guide rib 31 Upper diskette half (case half) 61 Cavity member (first mold) 62 Core member (second mold) 68 , 69 gate 70 recess 70A shallow bottom

Claims (2)

(57) [Claims] 1. A method for forming a case half of a floppy disk having a substantially rectangular flat and shallow circular concave record carrier storage portion on an inner surface and an arc-shaped disk guide rib protruding from a peripheral edge of the record carrier storage portion. A mold, wherein the mold comprises:
A first mold forming an outer surface of the case half; and a second mold forming an inner surface of the case half. A gate that opens in the thickness direction of the case half at a position close to the guide rib, the second mold has a recess forming the disk guide rib, and the recess near the gate has the recess. A mold for half-forming a case half of a floppy disk, wherein a shallow bottom portion in which the depth of the concave portion is smoothly reduced is formed. 2. The mold according to claim 1, wherein said shallow portion is reduced by 20 to 30 μm at a maximum point.