JPH06328520A - Mold for molding half case for floppy disk - Google Patents

Abstract

PURPOSE:To make it possible to displace easily and largely the position of a weld line of an upper case for a floppy disk by providing a projection at a position corresponding to the thick part on the side or a label area of the upper case among the engraved faces of a mold corresponding to the rear face of the upper case. CONSTITUTION:A projection T serving as a projecting pin on the projected part 10a corresponding to a recessed part for storing a disk body on the engraved face 10 of a movable mold 1 corresponding to the rear face of an upper case 4, on the side of a label area 42 and on the thick part 45b between it and the outer edge of the upper case, is assembled in such a way that the apex face thereof is projected by the height (h) from the engraved face 10. As the flow rate of one of the left and right resin flows flowing in gaps corresponding to thick parts between each of both sides of the label area of the upper case and the outer edge of the upper case can be controlled by means of an optical projection, it becomes possible to displace largely the weld line of a molded item.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die for molding at least an upper case of a pair of upper and lower half cases for accommodating a magnetic storage disk body in a 3.5-inch micro floppy disk. Is.

[0002]

2. Description of the Related Art A 3.5-inch micro floppy disk is constructed by housing a magnetic storage disk in a pair of upper and lower plastic half cases.
The upper case 90 of the pair of upper and lower half cases is shown in FIG.
As shown in (a) and (b), a shutter area 91 and a label area 92 are provided on the front surface with two recesses, and a back surface is provided with a recess 93 for accommodating a magnetic storage disk body. In addition, it has a shape in which a window 94 for introducing the magnetic head is provided within the range of the disk body accommodating recess 93. In the shutter area 91, a shutter S indicated by a dashed line in the figure is mounted so as to be slidable in the left-right direction so as to close the window 94.

When the upper case 90 is molded with a two-point gate mold, the gates are arranged at two positions sandwiching the window 94 on the engraved surface of the mold on the surface of the upper case corresponding to the shutter area 91. (Numerals 91a and 91b in the figure (a) show the gate marks left on the surface of the upper case 90 which is a molded product). The molten resin injected from both gates into the cavity is divided into left and right as indicated by the double-dashed line arrow in the figure, and the label area 9 of the cavity is mainly used.
Two thick portions 95a between both sides of the upper case and the outer edge of the upper case,
It is filled through the part corresponding to 95b.

[0004]

In order to eliminate defective molding due to gas, the mold for molding the upper case 90 as described above is usually made of resin separated on the left and right sides of the engraved surface on the back side thereof. A gas vent is provided at a position where it is considered to finally merge (the reference numeral 93a in FIG. (B) indicates the trace of the gas vent left on the back surface of the upper case 90 which is a molded product).

However, when molding is actually performed, the weld line WL of the molded product, which indicates the joining position of the left and right resin flows, often deviates from the position of the gas vent. When the weld line WL deviates from the gas vent, degassing is not performed completely, so that it is not possible to prevent the occurrence of defective molding due to gas. It is possible to shift the position of the weld line WL by adjusting the amount of resin injected from the left and right gates. For example, when using a normal cold runner or a valve gate type hot runner, the temperature of the left and right runners It is technically difficult to change the amount of resin injected from the left and right runners as the position of the weld line WL is greatly displaced only by adjustment, and there is a problem that the construction will be troublesome.

The present invention has been made in view of the above circumstances, and the position of the weld line of the upper case for the floppy disk can be relatively easily and largely shifted, and the molding metal for the two-point gate can be relatively large. It is intended to provide a type.

[0007]

In order to solve the above problems, a mold for molding a half case for a floppy disk according to the present invention has at least a cavity for molding an upper case of a pair of upper and lower half cases. The upper case is provided within the recess for storing the disc body in the upper case, and corresponds to either one of the two thick portions between the label area and the outer edge of the upper case. It is characterized in that the engraved surface of the die on the back surface side is provided with a protrusion for restricting the flow of the molten resin.

[0008]

According to the mold for molding the half case for the floppy disk of the present invention having the above-mentioned structure, the mold is injected into the cavity from the two gates on the left and right, and the gap is provided between both sides of the label area of the upper case and the outer edge of the upper case. Since the flow rate of one of the left and right two resin flows flowing through the gap corresponding to the two thick portions can be regulated by the protrusion formed on the engraved surface of the mold on the back surface of the upper case corresponding to the thick portion, It is possible to greatly shift the weld line of the molded product, which shows the joining positions of the left and right resin flows.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. First, the shape of the upper case for a floppy disk will be described. As shown in FIGS. 5 (a) and 5 (b), the upper case 4 has a substantially square thin-walled surface, and a shutter area 41 on which a shutter S (shown by a chain line) is slidably mounted in the left-right direction. In addition to the two concave portions of the label area 42 to which the label is attached, the shutter area 41 has a rectangular window 44 for introducing the magnetic head. Gate marks 41a and 41b are seen on both sides of the window 44 in the shutter area 41, corresponding to the gates of the mold. The two thick portions 45a and 45b between the label area 42 and the outer edge of the upper case are provided with a hole 47a for a light protector and a hole 47 for identifying a floppy disk, respectively.
b is formed.

On the back surface of the upper case 4, an outer frame 46a is formed over almost the entire outer edge portion thereof, and an arcuate rib 46b is formed continuously with the outer frame 46a. Inside the rib 46b, a disk body housing recess 43 for housing the storage disk body is formed. An annular rib 46c that rotatably supports the storage disk body and a reinforcing rib 46d are concentrically formed in the center of the disk body storage recess 43. Further, in the disk body accommodating recess 43, at a position opposite to the window 44 across the ribs 46c and 46d, a trace 43a is seen corresponding to the gas vent provided in the mold.

For molding the upper case 4 having the above-mentioned shape,
As shown in FIGS. 2 and 3, the mold for molding the half case for the floppy disk of the present embodiment is a so-called four-piece mold in which two pairs of upper and lower half cases are simultaneously molded, for a total of four. There is a movable mold 1 having engraved surfaces 10 and 11 corresponding to the shapes of the back surfaces of the upper case 4 and the lower case.
(Fig. 2) and engraved surface 2 corresponding to the surface shape of both cases
And a fixed mold 2 (FIG. 3) having 0 and 21.

When the two molds 1 and 2 are fitted together on the mating surface, as shown in FIG. 4, the engraved surface 10 of the movable mold 1 corresponding to the back surface of the upper case 4 and the fixed mold corresponding to the front surface of the upper case 4. The two engraved surfaces 20 form a cavity C corresponding to the shape of the upper case. The engraved surface 10 of the movable die 1 corresponding to the shape of the back surface of the upper case 4 is shown in FIGS.
As can be seen from the above, the convex portion 10a corresponding to the concave portion 43 for storing the disc body, the convex portion 10b corresponding to the window 44 and contacting the engraved surface 20 of the fixed mold 2, the step portion 10c corresponding to the outer frame 46a,
Each of the ribs 46b to 46d has grooves 10d to 10f, holes 47a and 47b, and projections 10g and 10h that are in contact with the engraved surface 20 of the fixed mold 2.

Further, projecting pins p for projecting the upper case 4 which is a molded product from the movable mold 1 are incorporated in a plurality of positions on the engraved surface 10 in a state where the tip end surface thereof is flush with the engraved surface 10. And the groove 1 on the convex portion 10a corresponding to the disc body accommodating concave portion 43 and corresponding to the ribs 46c and 46d.
A gas vent v is installed at a position on the opposite side of the convex portion 10b corresponding to the window 44 with the 0e and 10f interposed therebetween so as to be flush with the convex portion 10a.

Further, on the convex portion 10a of the engraved surface 10 corresponding to the concave portion 43 for storing the disk body, between the label area 42 (shown by a chain double-dashed line in FIG. 1) and the outer edge of the upper case. A projection T, which also serves as a projecting pin, is incorporated in the portion corresponding to the thick portion 45b with the tip end surface projecting from the engraved surface 10 by a height h. On the other hand, the engraving surface 20 of the fixed die 2 corresponding to the surface shape of the upper case 4 is formed by a concave portion having the thickness of the upper case 4 as shown in FIG. 4, and the bottom surface thereof has a concave portion as shown in FIGS. , Shutter area 41,
Convex portions 20a and 20b corresponding to the label area 42 and concave portions 20c and 20d corresponding to the thick portions 45a and 45b are formed.

Reference numerals 20e, 20f, and 20g in FIG. 3 denote finished surfaces with which the convex portions 10b, 10g, and 10h abut, respectively. Further, in the convex portion 20a corresponding to the shutter area 41, at a position sandwiching the finishing surface 20e,
Two gates g1 and g2 are provided. The upper case 4 is formed by using the mold for forming the half case for the floppy disk of this embodiment, which includes the movable mold 1 and the fixed mold 2.
When molding is performed, the molten resin injected from the two gates g1 and g2 is divided into left and right as shown by the double-dashed line arrow in FIG. It is filled through the space of the cavity corresponding to the thick portions 45a and 45b.

At this time, mainly the gate g1 (gate mark 4
The resin flow on the left side in the figure is not regulated at all, but is mainly injected from the gate g2 (the gate corresponding to the gate mark 41b) and is thick. Since the resin flow on the right side flowing through the portion 45b is directly regulated by the protrusion T protruding into the cavity, the molding showing the confluence position of the resin flow on the left and right, which is deviated to the left in FIG. 6 (a). The position of the weld line WL of the product (shown by a long broken line in FIG. 5A) can be largely moved to the right as shown by the solid line.

Therefore, as shown by the solid line in FIG. 5 (b), the weld line WL is set to the range of the gas vent v provided on the engraved surface 10 of the movable die 1 (in the figure, the mark 43a left on the molded product is (Shown), the gas vent v completes the degassing, and the occurrence of defective molding due to the gas is prevented. Upper case 4 which is a molded product
As shown in FIG. 5 (b), the marks of the protrusion T are formed on the back surface of the concave portion 4
Although it remains as 3b, this concave portion 43b is hidden inside when the floppy disk is assembled, so that there is no problem in appearance.

The amount of movement of the weld line WL can be adjusted by changing the protrusion height h of the protrusion T or the sectional area of the protrusion T. In the case of the embodiment, since the protrusion T also serves as a protrusion pin and can be easily removed from the movable mold 1, the protrusion height h of the protrusion T can be changed by simply replacing the protrusion with another one having a different length. Moreover, the cross-sectional area of the protrusion T can be changed by exchanging with a pin having the same projecting height and a different projecting section in cross-sectional area. Therefore, according to this embodiment, there is an advantage that the movement amount of the weld line WL can be adjusted relatively easily.

Contrary to the above description, when the position of the weld line WL deviates to the right in FIG. 5A, the resin flow on the left side of the engraving surface 10 of the movable die 1 flows. The protrusion T may be provided at a position corresponding to the thick portion 45a. The description of the embodiment of the present invention is as above,
The present invention is not limited to the above embodiments.

For example, in the above-mentioned embodiment, the projection T also serves as a projecting pin, but in the present invention, the projection T is simply a pin incorporated in a mold with its tip projecting from the engraved surface. Good. Further, the protrusion does not have to be a pin, and for example, the protrusion can be formed directly on the engraved surface of the mold. Although the embodiment has shown the case of taking four pieces,
The mold for forming the half case for the floppy disk of the present invention is not limited to taking four dies. Take 2 for example, 6
It goes without saying that the structure of the mold for molding the half case for the floppy disk of the present invention can be applied to a multi-cavity mold other than the 4-cavity mold such as the 8-cavity mold.
The structure of the present invention can also be applied to a single-die mold for molding only one upper case.

In addition, various design changes can be made without changing the gist of the present invention.

[0022]

As described above in detail, in the mold for molding the half case for the floppy disk of the present invention, the two cases of the right and left gates are injected into the cavity for molding the upper case, so that the label area of the upper case is By restricting the flow rate of one of the two left and right resin flows that flow through the gap corresponding to the two thick portions between the both sides and the outer edge of the upper case by the protrusion that is provided at the location corresponding to the flow path, It is possible to shift the weld line of the molded product, which shows the joining positions of the left and right resin flows, more easily and more largely than ever before.

Therefore, according to the molding die of the present invention,
It is easy to align the position of the weld line with the gas vent provided on the engraved surface of the mold, and the degassing by the gas vent is completely performed, so that it is possible to mold the upper case in which defective molding due to gas is prevented. it can.

[Brief description of drawings]

FIG. 1 is a front view showing, on an enlarged scale, a part of an engraving surface of a movable die in an embodiment of a molding die for a half case for a floppy disk of the present invention.

FIG. 2 is a front view showing the entire engraving surface of a movable die of the molding die of the above embodiment.

FIG. 3 is a front view showing the entire engraving surface of a fixed die of the molding die of the above embodiment.

FIG. 4 is a partially enlarged cross-sectional view of a cavity formed by combining engraving surfaces of the movable die and the fixed die.

5A and 5B are views showing an upper case molded by the molding die of the above embodiment, FIG. 5A is a front view and FIG. 5B is a rear view.

6A and 6B are views showing an upper case molded by a conventional molding die, in which FIG. 6A is a front view and FIG. 6B is a rear view.

[Explanation of symbols]

 T protrusion 1 movable type (mold) 10 engraving surface 42 label area 45b thick part

Claims (3)

[Claims] 1. A pair of upper and lower half cases for accommodating a magnetic storage disk body, each having two recesses of a shutter area and a label area on the front surface and a recess for accommodating the magnetic storage disk body at the center of the back surface. At least a cavity for molding an upper case having a window for introducing a magnetic head is provided in the shutter area and within the range of the disk body accommodating recess, and the upper case surface side corresponding to the shutter area. In a molding die having gates for injecting a molten resin into a cavity in two places on the engraved surface of the die, which sandwich a window, within a range of the disc body accommodating concave portion and in a label area. The flow of molten resin is regulated on the engraved surface of the mold on the back side of the upper case that corresponds to either of the two thick parts between both sides of the upper case and the outer edge of the upper case. Mold half case for floppy disks, characterized in that a projection that. 2. The mold for molding a half case for a floppy disk according to claim 1, wherein the protrusion is constituted by a pin incorporated in the mold with its tip protruding from the engraved surface. 3. The mold for molding a half case for a floppy disk according to claim 2, wherein the pin also serves as a projecting pin for protruding the molded product from the mold.