JPH08161856A - Injection molding method of case for recording carrier - Google Patents

Abstract

PURPOSE: To obtain an injection molding method of a case for recording carriers capable of molding upper and lower cases of different materials one of which consists of a transparent or translucent resin and the other consists of an opaque resin with one metal mold. CONSTITUTION: The same metal mold 10 is provided with a cavity 11 for molding the upper case and a cavity 12 for molding the lower case. The opaque molten resin is fitted into either one of these cavities and the transparent or translucent molten resin into the other cavity, respectively, and these resins are injection molded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for injection molding a plastic record carrier case containing a tape-shaped record carrier or a disk-shaped record carrier.

[0002]

2. Description of the Related Art As a case for a record carrier of this type, a transparent plastic molded article generally has a poor impact resistance, so that it is not a good idea to make both the upper and lower cases transparent. Therefore,
For example, a tape cartridge of an auto-reverse type is known in which the entire lower case of the main body case is molded with an opaque resin and the entire upper case is molded with a transparent resin so that the record carrier can be seen through from the outside. (For example, Japanese Utility Model Publication No. 4-19643). In this way, the upper case and the lower case, which are made of different materials, are injection-molded by different molds. Items that can be set with the same mold were limited to those of the same material.

[0003]

However, in the case where the upper case and the lower case are injection-molded by separate molds, the mold cost and the molding cost are very high.
An object of the present invention is to inject a case for a record carrier capable of reducing mold cost and molding cost in a case where one of the upper case and the lower case is molded with transparent or semitransparent resin and the other is molded with opaque resin. It is to provide a molding method.

[0004]

According to a first aspect of the present invention, when a record carrier case consisting of a plastic upper and lower case is injection molded, a cavity for molding the upper case and a lower case are formed in the same mold. A molding cavity is provided side by side, and one of the cavities is filled with an opaque molten resin, and the other cavity is filled with a transparent or translucent molten resin, and injection molding is performed. According to a second aspect of the present invention, in injection-molding a record carrier case composed of a plastic upper and lower case, a cavity for upper case molding and a cavity for lower case molding are provided side by side in the same mold. Filling one cavity with an opaque molten resin to perform primary molding of either the upper or lower case having a notch in a part, and passing the transparent or translucent molten resin from the notch through the runner to the other cavity. And then second-molding the other case.

[0005]

According to the first aspect of the present invention, the upper case and the lower case made of different materials can be injection-molded with one mold, one of which is transparent or translucent resin and the other of which is opaque resin. According to the second aspect of the present invention, an opaque lower case or upper case in which only the notch is transparent or translucent, and an entirely transparent or translucent upper case or lower case are formed of the same metal. Can be obtained in molds.
The transparent or semi-transparent cutout can be used as a portion through which the optical path is passed when an optical sensor detects whether or not the deck is properly loaded in actual use.

[0006]

【Example】

(First Embodiment) FIG. 1 is a plan view showing an example of the cavity arrangement of a set-up die used to carry out the injection molding method for a record carrier case according to the present invention, and FIG.
It is a line sectional view. FIG. 4 shows a case 1 of an 8 mm video tape cartridge as a concrete example of the case for the record carrier.
This tape cartridge constitutes a main body case 1 by abutting and integrally combining an upper case 2 made of a transparent or translucent resin and a lower case 3 made of an opaque resin. A tape-shaped record carrier 5 wound around a pair of left and right reels 4 is built in the main body case 1, and the tape-shaped record carrier 5 is provided from one reel 4 to one of the tape outlets 6 on the front and left sides of the main body case 1. From the front side of the case to the other reel 4 through the other tape outlet 6.
To be wound up. A front cover 7 and a back cover 8 for protecting the tape are attached to the front side of the main body case 1.

1 and 2, one die 1
Two cavities 11 for molding the upper case and two cavities 12 for molding the lower case are arranged side by side at 0. A runner 13 of a hot runner system is provided between the cavities 12 for molding the lower case, and a sprue 14 and a nozzle 15 for primary molding are provided at the center of the runner 13. In addition, another part 1 of the cavity 12 for molding the lower case
Another trunk runner 16 of the same hot runner system is provided between 2A, and a sprue 17 for secondary molding is provided at the center of this trunk runner 16. The other place 12A of the cavity 12 is, for example, a place where the horizontal bottom wall 3a and the vertical wall 3b corresponding to the bottom side of the tape outlet 6 of the lower case 3 intersect. Other places 12 of this cavity 12
As shown in FIG. 2 (A), a slide core 19 for forming a notch and a nozzle 20 for secondary forming are vertically arranged in A, and the location 12A and a cavity for forming an upper case are set in A. A branch runner 21 is provided between the branches 11.

Thus, as shown in FIG. 2A, the slide core 19 is advanced into the cavity 12 for molding the lower case, and the sprue 14 for primary molding is used to remove the opaque molten resin for molding the lower case. The lower case 3 is primarily molded by filling the cavity 12 of FIG. As the opaque resin, for example, a material having excellent impact resistance in which butadiene rubber is mixed with polystyrene is used. Next, as shown in FIG. 2B, the slide core 19 is retracted, and the transparent or translucent molten resin is removed from the secondary molding sprue 17 by the recess of the slide core 19. 22 and the cavity 11 for molding the upper case, the notch 22 is closed by the transparent or semitransparent closing plate 23 as shown in FIG. 3, and all other parts are opaque in the lower case. 3 and the upper case 2 which is entirely transparent or translucent is obtained. Examples of the transparent or translucent resin include polystyrene, which is compatible with the primary molding material of the lower case 3 described above.

(Second Embodiment) FIG. 5 shows a second embodiment.
Also in this embodiment, two cavities 11 for molding the upper case and two cavities 12 for molding the lower case are arranged side by side in one mold 10. A runner 13 of a hot runner system is provided between the cavities 12 for molding the lower case, and a sprue 14 and a nozzle 15 are provided at the center of the runner 13. A hot runner system runner 24 is also provided between the upper case molding cavities 11 and a sprue 25 is provided at the center of the runner 24.
And a nozzle 26. In the mold configured as described above, the opaque molten resin is filled from the sprue 14 into the lower case molding cavity 12 so that the lower case 3 can be formed.
At the same time, the upper case 2 can be molded by filling the cavity 11 for molding the upper case from the sprue 25 with the transparent or translucent molten resin.

[0010]

According to the invention of claim 1 of the present invention,
An upper case molding cavity and a lower case molding cavity are provided in the same mold, and one of the cavities is filled with an opaque molten resin, and the other cavity is filled with a transparent or translucent molten resin. By injection molding, upper and lower cases made of different materials, one of which is transparent or semi-transparent resin and the other of which is opaque resin, can be molded by one mold, and each mold is molded by a separate mold. This is advantageous because it can be significantly reduced compared to the cost and molding cost.

According to the second aspect of the present invention, a lower or upper case in which only some of the notches are made of transparent or semitransparent resin and all other portions are made of opaque resin,
The upper and lower cases, which are entirely made of transparent or translucent resin, can be injection-molded with a single mold, and also in this case, the mold cost and molding cost can be reduced.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of a cavity arrangement of a mold used for carrying out an injection molding method of a record carrier case of the present invention.

2 is a sectional view taken along the line AA in FIG. 1, where (A) is a primary molding state diagram and (B) is a secondary molding state diagram.

FIG. 3 is a partial cross-sectional view of a lower case.

FIG. 4 is an external perspective view of an 8 mm video tape cartridge.

FIG. 5 is a plan view showing a cavity arrangement example of a mold of another embodiment.

[Explanation of symbols]

 1 Case for Record Carrier 2 Upper Case 3 Lower Case 10 Mold 11 Cavity for Molding Upper Case 12 Cavity for Molding Lower Case 21 Runner 22 Notch

Claims (2)

[Claims] 1. When injection-molding a record carrier case composed of a plastic upper and lower case, a cavity for upper case molding and a cavity for lower case molding are provided side by side in the same mold, and one of the cavities is provided. An injection molding method for a case for a record carrier, characterized in that an opaque molten resin is filled in the other cavity and a transparent or semitransparent molten resin is filled in the other cavity. 2. When injection molding a record carrier case composed of a plastic upper and lower case, a cavity for upper case molding and a cavity for lower case molding are provided side by side in the same mold, and one cavity is made opaque. A step of primary molding one of upper and lower cases having a notch in a part by filling it with molten resin, and filling the other cavity from the notch with a runner through the runner It consists of the process of secondary molding the case,
Injection molding method for record carrier case.