JPH01130372A - Tape reel - Google Patents

Abstract

PURPOSE:To improve the yield of molding and the mass-productivity by repeatedly forming projecting parts and recessed parts on the outside peripheral surface of a reel hub inner cylinder part and coupling the inner cylinder part and an outer cylinder part by ribs provided in positions of recessed parts. CONSTITUTION:With respect to a tape reel 72, a reel hub 75 consists of an inner cylinder part 46 and an outer cylinder part 47, and ribs 70 which couple and reinforce both cylinder parts 46 and 47 are provided in positions of recessed parts 49 on the outside peripheral surface of the inner cylinder part. A mold 86 used to form this tape reel 72 is provided with a slit 85 in the position of a thick projecting part 53 of a wall part 82. Consequently, though the injection pressure acts on a wall part 82a opposite to a gate 62 at the time of injecting a resin 60, cracks do not occur in the bottom part of the slit to considerably improve the durability of the mold because the slit 85 is formed in the position of the projecting part 53 which is thick and has a high strength. Thus, the yield of molding and the mass-productivity are improved.

Description

[Detailed description of the invention] B. Industrial application fields The present invention relates to tape reels.

As shown in FIGS. 6 and 7, a conventional tape cassette for a video tape recorder, for example, has a lower half 32 containing a pair of left and right reel hubs 15 and 45 around which a magnetic tape 31 is wound, and each reel hub. It has a structure in which an upper half 34 to which a leaf spring 33 that presses and holds is fixed is joined. Reel hub 15.45, reel flange 1.4
1. Each reel structure is formed by a pivot 25,28. In the figure, 35 and 36 are a pair of left and right transparent windows.

In such a tape cassette 30, the reel hub 1
Lower flange 42.43 with 5.45 and upper flange 1.
41 separately, and then integrate them,
A magnetic tape 31 is wound around each reel hub. For example, as for the lower flange 42 (the same applies to 43), as shown in FIG.
The inner cylinder part 46 has a convex part 48 on its outer peripheral surface.
A repeating pattern of and recesses 49 is formed.

The two cylindrical portions 46 and 47 are radially connected and reinforced by a thin lip 50 provided at the position of the convex portion 4B. Note that an annular welding pedestal 17 for welding and fixing the upper seven flange is provided on the upper surface of the inner cylindrical portion 46;
A pivot mounting portion 20 is provided inside thereof via a ring-shaped projection 18 . In addition, the reel flange 420
The peripheral edge is provided with a stopper [66] that fits into a stopper when it is housed in a cassette half (not shown). Further, the wall portion 47 is formed with a fitting groove 47a for fitting and fixing the end portion of the wound tape with a clamping tool (not shown).

To mold the flange 42, a mold having a pattern opposite to that shown in FIG. 8 is used. As such a mold, as shown in FIGS. 9 to 11, the inner cylindrical portion 46 is
A wall portion 52 corresponding to the gap 51 between the outer cylindrical portion 47 and the outer cylinder portion 47 is provided, and a convex portion 53 (a pattern opposite to the concave portion 49 described above) and a concave portion 54 (a pattern opposite to the convex portion 48 described above) is provided on the inner surface of this wall portion. and reverse pattern), the above-mentioned lip 50 is formed in the recess 54.
A gold plate 56 is used in which a slit 55 corresponding to the size of the gold plate 56 is formed. In FIG. 11, -dotted chain lines 57,58,59 indicate
The molds combined with the mold 56 are shown, and during molding, resin 60 is injected through the gate 61 of the mold 57. Note that 62 in the figure is a hole for inserting an ejector pin.

However, the injection pressure at this time reaches several hundred to nine, and the resin from the gate 61 flows around the space 63 between the molds, particularly in the metal wall portion 52a located on the opposite side of the gate 61. is subjected to extremely large pressure from both sides by the flowing resin. As a result, the 10th
As shown in the figure, the part where the slit 55 is located is a concave part 54 and is quite thin, so its strength is low, and a crack 64 appears in this thin part (the lowest part of the slit 55), causing the mold 56 to break. Resulting in. In some cases, the wall portion 52 may break.

OBJECTS OF THE INVENTION An object of the present invention is to provide a tape reel that improves the molding yield, has sufficient strength, and is suitable for mass production.

The surface is formed into a repeating shape of convex parts and concave parts along the circumferential direction, and the inner cylinder part and the outer cylinder part are connected to each other by a lip provided at the position of the recess part. This relates to a tape reel.

E, Example Embodiments of the present invention will be described below with reference to the drawings.

However, parts common to those of the conventional example described in FIGS. 6 to 11 may be given common reference numerals and explanations thereof may be omitted.

In the tape reel (lower flange) 72 of this embodiment shown in FIGS. 1 to 3, the reel hub 75 has an inner cylinder part 46 and an outer cylinder part 4.
Although it consists of 7, it connects both cylindrical parts 46 and 47,
It is extremely important that the reinforcing lip 70 is provided at the position of the recess 49 on the outer peripheral surface of the inner cylinder. This also applies to the other lower 7 lunges.

Note that the pivot 25 is inserted and housed in the pivot mounting portion 20 of the reel hub 75. The reel 7 lunge 1 is placed on this, and at this time, the positional relationship of each member is as follows.

That is, the protrusion 26 of the pivot 25 penetrates the hole 3 and protrudes upward, and its apex protrudes to a position higher than the upper surface 1a. Here, the chain line in FIG. 3 represents the leaf spring 33. The base 27 of the pivot 25 is the mounting part 2
0 and is positioned by the mounting portion 20 and the recess 7. The protrusion 9 of the reel 7 flange 1 is placed within the wall 47, and the reel flange 1 is placed on the protrusion 18. At this time, the fusion pedestal 17 and the fusion protrusion 8
come into contact with. When positioning is completed in this way,
Using an ultrasonic welding device, a vibrating horn is applied to the welding protrusion 8 to apply ultrasonic energy, thereby welding the flange 1 to the hub T5, resulting in the state shown in FIG. 3. shall be.

In the above, the pivot 25 is made of polyoxymethylene (polyacetal) which has high wear resistance. On the other hand, the reel hub 75, which does not come into direct contact with the leaf spring 33, is made of AB8 resin (acrylonitrile-butadiene-styrene copolymer resin) K, and the reel flange 1 is made of JinS resin (acrylonitrile-styrene copolymer resin). It is molded.

To mold the tape reel (lower flange) 72 of the tape cassette according to this embodiment, a mold 86 as shown in FIGS. 4 and 5 is used. This gold M186 differs from the mold 56 described above in that a slit 85 is provided in the wall portion 82 at the position of the thick convex portion 53. Therefore, when injecting the resin 60 as shown in FIG. 5, even if injection pressure is applied to the wall 82a on the opposite side to the gate 61, the slit 85 is formed in the thick and strong protrusion 530. Therefore, the above-mentioned cracks do not occur at the bottom of the slit 85 (or in the vicinity thereof), and the durability of the mold is greatly improved. As a result, the molding yield is greatly improved and mass productivity is excellent.

Although the present invention has been illustrated above, the embodiments described above can be further modified based on the technical idea of the present invention.

For example, the above-described uneven shape of the reel hub may have other patterns, and the positions, shapes, and sizes of the lips may also be varied. Further, in the above example, the gate 61 of the mold was placed around the reel hub, but it will be understood that the present invention is highly effective in this case. However, the gate may of course be located at the center of the reel hub. In addition, in the above-mentioned embodiment, the pivot may be integrally provided on the reel hub side.

Effects of the Invention As described above, the present invention is provided with a lip that connects to the outer cylindrical portion at the concave position of the outer peripheral surface of the inner cylindrical portion of the reel hub, so the mold used for molding the reel hub has a convex wall thickness. A slit corresponding to the lip above can be provided in the wall of the
The bottom of the slit (
(or in the vicinity), no cracks occur, and the durability of the mold is greatly improved. This greatly improves the molding yield and provides excellent mass productivity.

[Brief explanation of the drawing]

Figures 1 to 5 show embodiments of the present invention. Figure 1 is a plan view of the lower 7 lunges, and Figure 2 shows the upper 7 lunges fixed to the reel hub side. Plan view, Figure 3 is a sectional view taken along the line m-m in Figure 2, Figure 4 is a plan view of the mold, and Figure 5 is a cross-section of the mold during molding taken along the line v-v in Figure 4. It is a diagram. 6 to 11 show conventional examples, in which FIG. 6 is a plan view of a tape cassette for a video tape recorder, FIG. 7 is a sectional view taken along the line ■-■ in FIG. 6, and FIG. 8 is a plan view of the lower flange, Figure 9 is a plan view of the mold, Figure 10 is a side view of the mold, and Figure 11 is a cross-sectional view of the mold during molding along line XI-XI in Figure 9. be. In addition, in the symbols shown in the drawings, 1...... Upper flange 2
5・・・・・・・・・・・・・・・ Pivot 46...
・・・・・・・・・・・・ Inner cylinder part 47・・・・・・
......Outer cylinder part 48.54... Convex part 49.53... Concave part 57.58.59.86... Mold 61. ...
・・・・・・・・・・・・ Kate 62・・・・・・・・・
・・・・・・ Ejector pin insertion hole TO・・・・・・
・・・・・・・・・ Reply T2・・・・・・・・・・・・
...Lower 7 lunges 75...
・ Reel No Fu 82・・・・・・・・・・・・・・・
Wall portion 85 is a slit. Agent: Hiroshi Aisaka, Patent Attorney, ↓Memme-9, ``J'' Figure 7, Figure 9, Figure 1, O, Figure 11, Hess Mouse, Figure 11

Claims (1)

[Claims] 1. In a tape reel provided with a reel hub for winding the tape, the reel hub consists of an inner cylinder part and an outer cylinder part, and the outer circumferential surface of the inner cylinder part has repeated convex parts and concave parts along the circumferential direction. What is claimed is: 1. A tape reel, wherein the inner cylindrical part and the outer cylindrical part are connected to each other by a rib provided at the position of the recess.