JP2754847B2 - Video cassette half - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a video cassette half provided as a part of a video cassette tape for a VTR.

2. Description of the Related Art A video cassette tape for a VTR is composed of two video cassette halves, an upper video cassette half 1 as shown in FIG. 1 and a lower video cassette half 2 as shown in FIG. The video tape wound on a reel is housed in a box-shaped video cassette case.

Each of the upper video cassette half 1 and the lower video cassette half 2 includes a rectangular face plate 3 and a side plate 4 provided on an outer edge portion of one face of the face plate, and is generally formed by injection molding. To be
On the outer surface of these cases, that is, on the center of the other surface of the face plate 3, a gate portion 5 into which a molten resin is injected at the time of injection molding is set.

Also, tapping bosses 6 provided with screw portions for connecting the two video cassette halves are provided on the inner surfaces of the video cassette halves 1 and 2, that is, on one surface of the face plate 3.
, A guide wall 7 for guiding the tape reel, a projection 8 for fixing a pinch roller and other accessory parts, and the like. Further, a confirmation window 9 for confirming the remaining amount of the tape is provided on the face plate of the upper video cassette half 1, and a reel hole 10 for fitting a tape reel is provided on the face plate of the lower video cassette half 2.

On the inner surfaces of the video cassette halves 1 and 2, ribs 11 are formed from the vicinity of the back surface of the gate portion 5, and are joined to the side plate 4 at a joining portion 12. In addition, the rib 11 generally has the same rib thickness from the joint 12 to the other end.

[Problems to be Solved by the Invention] When a video cassette half having such a configuration is molded by injection molding, the side plate is often in a state opposite to a joint portion with a rib and clearly in a state other than the other portion. Parts with different patterns, so-called flow marks and weld marks, occur.

The following causes can be considered for generation of these flow marks and weld marks. In other words, when injection molding a relatively wide molding such as the video cassette half, the molten resin injected from the molding die must be filled up to every corner of the cavity formed by the die. Injected at relatively high pressure. For this reason, the pressure of the molten resin tends to be excessive at a portion near the gate portion of the molding object, for example, at a portion such as the rib portion of the video cassette half as compared with other portions.

On the other hand, there are two possible routes for the molten resin to reach the junction from the gate. One is a path that flows from the gate to the rib, and reaches the joint from the rib side, and the other is a path from the gate through the face plate,
This is the route that reaches the joint from the side plate side.

And the molten resin injected from the gate plate at high pressure,
Each of these two paths leads to the junction,
Here they meet and fuse. At this time, the resin at the joint may be in a higher pressure state to be in a fusion state different from other parts, or the respective molten resins that have passed through the two paths may not be completely fused. Such a portion appears on the surface of the molded object as a flow mark or a weld mark.

When these flow marks and weld marks are generated, the appearance is impaired, and the resin is segregated at the flow mark or the weld mark, and the strength may be unstable. For this reason, it has been an important issue to prevent the occurrence of these flow marks and weld marks.

Means for Solving the Problems The present invention has been made to solve the above-mentioned problems, and comprises a rectangular face plate and a side plate standing upright on an outer edge portion of one surface of the face plate. A video cassette half for molding by injecting molten resin from a gate portion set at the center of a face plate, wherein a rib is formed at an intersection of the face plate and the side plate, and a rib at a junction between the rib and the side plate. The thickness is set to 1/3 to 1/2 of the rib thickness of the other portions.

According to the present invention, the molten resin injected from the molding die during the injection molding flows from the gate portion to the rib portion, reaches the joining portion from the rib side, and passes from the gate portion to the face plate portion. The joint reaches the joint through two paths from the side plate to the joint.

At this time, the molten resin that has flowed from the gate to the side plate through the face plate is filled into the joint in the same manner as in the above-described conventional example, but the molten resin that has flowed from the rib is the rib end of the joint. Is reduced to 1/3 to 1/2 of the rib thickness of the other portions, the amount of the molten resin flowing into the joint portion is suppressed.

For this reason, the molten resin is prevented from being in a high pressure state at the joint as in the past, and the molten resins that have passed through the two paths are completely fused with each other, so that flow marks and weld marks are generated. Can be prevented.

If the thickness of the rib end portion of the joining portion is larger than 1/2 of the rib thickness of the other portion, the amount of the molten resin flowing into the joining portion is not sufficiently suppressed. Therefore, a flow mark or a weld mark may be generated. On the contrary, the thickness of the rib end of the joint is
If the rib thickness is less than 1/3 of the thickness of the other portion, the strength of the joining portion becomes insufficient, and the half may be damaged.

[Embodiment] A video cassette half according to the present invention comprises a video cassette case composed of upper and lower two video cassette halves, similarly to the conventional example. The configuration is substantially the same as the conventional example shown in FIG. 1 and FIG.

That is, each of the video cassette halves 1 and 2 includes a rectangular face plate 3 and a side plate 4 provided on an outer edge of one surface of the face plate 3. That is, on one surface of the face plate 3, a tapping boss 6 provided with a screw portion for connecting the upper and lower video cassette halves, a guide wall 7 for guiding a tape reel, a pinch roller and other attached parts are fixed. Projections 8 are provided. Further, a confirmation window 9 for confirming the remaining amount of the tape is provided on the face plate 3 of the upper video cassette half 1, and a reel hole 10 for fitting a tape reel is provided on the face plate 3 of the lower video cassette half 2.

Further, since the video cassette halves 1 and 2 are formed by injection molding, a gate portion 5 at the time of injection molding is set on the outer surface thereof, that is, the center of the other surface of the face plate 3.

Further, ribs 11 are provided on the inner surfaces of the video cassette halves 1 and 2 from near the back side of the gate portion 5 and are joined to the side plate 4 at a joint portion 12.

FIG. 3 is a perspective view showing the rib portion, and is a perspective view of the cross section AA shown in FIG. 1 as viewed in the direction of the arrow, and as shown in FIG. Is set to 1/3 to 1/2 of the rib thickness L of the other portions.

For example, in a video cassette half for VHS, the thickness L of the rib is generally set to 0.8 to 1.2 mm. The rib of the conventional video cassette half is connected to the side plate while keeping this thickness.

Therefore, as one embodiment of the present invention, the thickness L of the ribs other than the joint 12 is set to 1.2 mm, and the thickness l of the rib 11 at the end of the rib 11 at the joint 12 is set to 0.5 mm. Was injection-molded, and the occurrence rates of flow marks and weld marks at this time were measured and compared with those of the conventional example.

In addition, as for the injection molding mold for molding the video cassette half of the present embodiment, the mold of the conventional mold, in which the width of the groove for molding the end of the rib connected to the joining portion is reduced to 0.5 mm, is used. used.

As a result of injection molding the video cassette half of the present invention with such a mold, the occurrence rate of flow marks and weld marks, which was conventionally 80 to 90%, was reduced to 10 to 20% in the present embodiment. . At this time, there was no occurrence of a defect or the like in strength at the joint.

Thus, the rib thickness at the end of the rib joined to the side plate is
By setting the thickness of the ribs in other parts to 1/3 to 1/2, of the molten resin injected from the gate at a high pressure, the amount of the molten resin flowing into the joint through the ribs is suppressed. Can be. On the other hand, the molten resin flowing from the face plate portion to the joint portion through the side plate is filled as in the related art,
The molten resin flowing from the two paths is completely fused and united at the joint between the rib and the side plate.

For this reason, in the video cassette half of the present invention, it is possible to reduce the occurrence of flow marks and weld marks appearing on the side plates, and to prevent the loss of aesthetic appearance and the lack of strength of the joint portion caused by these. be able to.

In addition, the present invention is to modify the other parts of the mold and other devices only by narrowing the part of the injection molding mold for molding the video cassette half in which the rib end of the joint is molded. Since there is no need, there is an advantage that it can be easily implemented.

Furthermore, in the present invention, the object is to prevent a flow mark or a weld mark generated at the joint between the rib and the side plate through which the high-pressure molten resin flows near the gate, but other joints such as guides Even when a flow mark or a weld mark is generated at a joint portion between a wall and a side plate, it is possible to prevent the generation by applying the present invention.

[Effects of the Invention] As described above, according to the present invention, the molten resin passing through the rib portion and the molten resin passing through the side plate from the face plate portion are completely fused at the joining portion and integrated, so that this portion is formed. The flow mark and the weld mark generated on the side plate can be prevented, and the appearance of the side plate surface can be prevented from being spoiled, and the strength of the joint can be prevented from becoming unstable.

In addition, the present invention can be easily implemented without changing other parts by narrowing a part of the injection mold where the rib end is formed.

[Brief description of the drawings]

FIGS. 1 and 2 are plan views showing a video cassette half of the present invention. FIG. 1 shows an upper video cassette half, and FIG. 2 shows a lower video cassette half. FIG. 3 is a perspective view of the video cassette half cut along the section AA in FIG. 1 and viewed in the direction of the arrow. The basic configuration of the conventional video cassette half is substantially the same as that of FIGS. 1 and 2. 1 upper video cassette half, 2 lower video cassette half, 3 face plate, 4 side plate, 5 gate unit, 11 rib, 12 joint, l rib at joint Rib thickness at the end, L ... Rib thickness at portions other than the joint.

Claims (1)

(57) [Claims] 1. A face plate having a rectangular shape and side plates erected on an outer edge of one face of the face plate, and molded by injecting a molten resin from a gate portion set at a central portion of the face plate. A video cassette half, wherein a rib is formed at an intersection of the face plate and the side plate, and a rib thickness at a joining portion between the rib and the side plate is 1/3 to a rib thickness of other portions. A video cassette half characterized by being 1/2.