JPS5942392B2 - Cassette case manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a cassette for storing a magnetic tape cassette.

This type of cassette case has a structure in which two cases 1 and 2 are combined together, as shown in FIG.

That is, a box-shaped pocket 3 for storing a magnetic tape cassette (not shown) is provided on the inner surface of the case 1, and both side plates 3a and 3b in the width direction of the pocket 3 are inserted between the side plates 2a and 2b of the case 2. The bottom plate 2c of the case 2 is provided with a notch 4 corresponding to the rotation radius of the pocket 3, and the pocket 3 is rotated through the notch 4. The structure is such that case 2 is closed by case 1. Cases 1 and 2 are
Normally, it is constructed from a plastic molded product, but when viewed as a cassette case, the top plate 1a of the case 1 is the front part that attracts the most attention, and the quality of its finish determines the commercial value of the cassette case. I will do it. Therefore, when molding the case 1, conventionally, a resin injection port was provided on the side plate 3a or 3b of the pocket portion 3 so that the resin injection mark P1 was not visible from the front. FIG. 2 is a partial schematic sectional view of the mold in this case, where 5 is a mold cavity, 6 is a mold core, T is a mold slide core, and 8 is a runner pull. The resin injected from part A passes through the runner pull 8 and enters the mold cavity 5, mold slide core 6 and slide The product portion 9 formed by the core T is injected as shown by the arrow c. However, as mentioned above, if the resin is injected from the lateral direction of the side plate 3a (or 3b) of the case 1,
As shown in FIG. 3, a resin portion 14 formed by the runner pull 8 remains between the molded products 10 to 13 of the case 1.

This resin portion 14 is redundant after molding, and needs to be removed from the molded products 10 to 13 that form the case 1. Therefore, in the conventional molding method, the resin portion 14 equal to the volume of the runner spool 8 is wasted, resulting in a disadvantage of increased costs. In particular, due to the recent rise in oil prices, the price of resin has increased significantly, and in order to reduce product costs, it is necessary to avoid waste of resin as much as possible.
Improvement is strongly desired. In order to eliminate such waste of resin and at the same time automate the molding process, a molding method without runner pull, that is, a runnerless molding method, is being attempted. However, in the case of this runnerless molding method, it is necessary to inject the resin from directly above, so when trying to mold a force set case using the runnerless molding method, the resin injection gate must be installed on the soil plate 1a of the case 1. I don't get it,
Gate marks remain on the top plate 1a, which serves as the product surface, resulting in a drawback that the product value is reduced. Furthermore, since the top plate 1a of the case 1 is thin, the resin does not flow smoothly, resulting in flow marks and the like. For this reason, despite the above-mentioned advantages of the runnerless molding method, when molding force set cases, the molding method using runner pulls still has to be used. The present invention solves the above-mentioned conventional technical problems, and enables a force setting case to be manufactured at a low cost without causing wastage of resin or reduction in product value, and in addition, the flow of the resin is smooth and no flow marks occur. The purpose is to provide a manufacturing method.

In order to achieve the above object, the method for manufacturing a force setting case according to the present invention uses a mold to manufacture a force setting case which is a resin molded product having a pocket portion for storing a magnetic tape cassette inside. , using a mold having a resin injection gate in which at least a portion of the hole diameter overlaps the edge of the slide core in a portion corresponding to a corner of the top plate constituting the pocket portion; It is characterized in that a resin injection port is provided above the resin injection port, and resin is directly supplied from the resin injection port to the resin injection gate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The content of the present invention will be specifically described below with reference to the accompanying drawings, which are examples.

FIG. 4 is a plan view of the case 1 obtained by the manufacturing method according to the present invention, in which a resin injection gate mark P2 remains at the corner of the upper surface plate 1a of the case 1, which is to be a plastic case.

This position is generally padded and embossed to prevent damage to the puta, so as shown in Figure 1, the case 2
Even when it is commercialized in combination with the gate mark P2, the gate mark P2 is not noticeable and does not impair the commercial value. FIG. 5 is a partial schematic cross-sectional view of a mold for explaining the manufacturing method according to the present invention, taken along the line B1--B1 in FIG. 4.

In the figure, 15 is the mold cavity, 16 is the mold core,
17 is a mold slide core, 18 is a torpedo, 19 is a product portion formed by the above-mentioned members, and f is a resin injection gate. As described above, the resin injection gate f is provided at a portion corresponding to the corner of the top plate 1a of the case 1,
At this time, a portion of the hole diameter of the gate f is provided so as to overlap the edge 17a of the slide core 17. A torpedo 18 is positioned above the resin injection gate f to form a resin injection port, and resin is directly supplied from the resin injection port to the resin injection gate f. With this configuration, the resin supplied through the side of the torpedo 18 that is kept warm is transferred from the gate f to the product section 1.
9, the edge 17a of the slide core 17, as shown by arrows D and e, has an upper surface portion 19a corresponding to the upper surface plate 1a of the case 1, and a rear surface portion corresponding to the side plates 3a, 3b or the back plate. Since the flow is divided into 19b, the flow of the resin becomes very smooth. As a result, troubles such as flow marks that occur due to the thin wall thickness when the soil flows only on the soil surface part 19a, overfilling that occurs when the soil flows only on the back surface part 19b, movement obstruction of the slide core 17, or soil Surface portion 19a
Various troubles such as the occurrence of weld marks can be effectively prevented, and it becomes possible to manufacture force set cases of high quality and high commercial value. In addition, with the above configuration, as shown in FIG. 6, when obtaining a plurality of products, resin injection gates P3 to P6 can be provided for each product 21 to 24, so runnerless molding is possible. It becomes possible,
Waste of resin due to runner pulls is eliminated, the process can be easily automated, and force set cases can be manufactured efficiently and at low cost.

As described above, the method for manufacturing a force setting case according to the present invention is suitable for manufacturing a force setting case which is a resin molded product having a pocket portion for storing a magnetic tape set inside using a mold. , a mold having a resin injection gate in which at least a portion of the hole diameter overlaps the edge of the slide core is used in a portion corresponding to the corner of the top plate constituting the pocket portion; Since a resin injection port is provided above and the resin is directly supplied from the resin injection port to the resin injection gate, the following effects can be obtained.

(1) Since the resin injected from the gate is divided at the edge of the slide core, the flow of resin becomes extremely smooth, resulting in flow marks on the top plate, overfilling on the back plate or side plate, and accompanying slides. It is possible to prevent troubles such as core movement obstruction and weld marks on the top plate, and to manufacture a force setting case of high quality and high commercial value.

(2) Since a runnerless molding method can be adopted, there is no waste of resin due to runner pulls, the force set case can be manufactured at low cost, and the process can be automated, improving mass productivity.

(3) Since the resin injection gate mark is located at the corner of the top plate where it is less noticeable, the commercial value of the force setting case is not impaired.

[Brief Description of the Drawings] Fig. 1 is a perspective view of a conventional force setting case, Fig. 2 is a partial schematic sectional view of a mold for manufacturing a conventional force setting case, and Fig. 3 is a perspective view of a conventional force setting case. Plan view of the obtained molded product, No. 4
The figure is a plan view of a force set case obtained by the manufacturing method according to the present invention, FIG. 5 is a partial schematic sectional view of a mold for explaining the manufacturing method according to the present invention, and FIG. 6 is a mold FIG. 1...Case, 1a...Top plate, 15
...Mold cavity, 16...Mold core, 17...Slide core, 17a...
・Edge, f...Resin injection gate.

Claims (1)

[Claims] 1. When manufacturing a cassette case, which is a resin molded product, which has a pocket portion for storing magnetic tape cassettes inside using a mold, a hole diameter is A mold having a resin injection gate at least a portion of which extends over the edge of the slide core is used, a resin injection port is provided above the resin injection gate, and the resin injection port is connected to the resin injection gate. A method for manufacturing a cassette case characterized by directly supplying resin.