JPS5923260Y2 - Tape reel for video cassette - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a tape reel for video cassette tape.

In general, this type of tape reel is made of plastic, and one of the flanges is provided at both ends of a bubble around which the magnetic tape is wound, one of which is molded separately from the bubble, and the rear column and the corresponding free end of the bubble are exposed to ultrasonic waves. It is fixed by welding etc.

Conventionally, during the installation process, the central cylindrical portion of the free end of the bub was often damaged.

Therefore, the present applicant discloses the present invention with the main purpose of investigating the cause and taking countermeasures to provide a tape reel with sufficient strength.

A tape reel according to an embodiment of the present invention is shown in FIG. 1 and subsequent figures, but in order to understand the strength problems, the known components will be explained first.

The bubble 1 has one flange 2 integrally molded with plastic at one end, and the other end is a free end 3.
Separate flange 4 injection molded separately from plastic
is attached to the rear pillar.

The illustrated tape reel is an example in which the outer peripheral surface of the bubble 1 is largely divided into two halves 1a and lb, but the two halves are generally snap-locked to each other. Stopping means 5a.

5b, and the circumferential surfaces 6a and 6b together form the outer circumferential surface of the bub around which the tape is wound.

Generally, this structure also serves to hold the tape end (not shown), and the tape end is held between the two halves 1a and lb when the two halves 1a and lb are assembled.

However, in other tape reels, one half 1a is formed into a cylindrical shape that covers almost the entire circumference, and a space formed radially inward from a slightly spaced part in the circumferential direction is used as the tape holding hole. There are some things that can be done, and either one is fine for the purpose of the proposal.

There is an inner cylindrical portion 7 relative to the outer peripheral surface portions 1a, lb of the bub, and in the tape reel shown, this inner cylindrical portion 7 is further divided into two concentric portions, namely, a central cylindrical portion 8 and a radially outer cylinder thereof. I am admonishing the wall part 9.

The interior of the inner cylinder portion 7 consisting of these two portions 8 and 9 has a structure shown in the cross section taken along the line III--III in FIG.

That is, a receiving hole 1 into which a well-known reel holding shaft (not shown) on the tape transport side of the tape is fitted.

is opened at the end of the bub that is not visible in FIG. A plurality of engagement ribs 11 (generally 60
(six at 40° intervals or nine at 40° intervals) for engagement with complementary ribs (not shown) on the reel engaging shaft.

This reel shaft receiving hole 10 and the rib 11 on its inner wall surface...
is also clearly shown in the perspective view from the back of FIG.

The central cylindrical portion 8 has a small papillary projection 12 at the center tip on the front surface side, which, as is well known, comes into contact with an elastic presser piece (not shown) on the cassette case side. This is to ensure smooth reel rotation.

From this small protrusion, a wall section 14 that stands up in the axial direction is formed through the upper surface section 13 that tapers slightly downward, progresses downward, expands in the radial direction midway in the length direction, and forms a connecting annular section 15. and continues to the cylinder wall portion 9.

On the inner periphery of the cylindrical wall portion 9, a plurality of bosses 16 are provided at appropriate intervals in the circumferential direction (in the case shown, there are six bosses 16 at intervals of 60').
protrudes in the axial direction.

On the other hand, in the separate flange 4, a central opening 17 is opened in the center, through which the small protrusion 12 and the upper surface part 13 that supports the small protrusion 12 are removed.
The peripheral edge part 18 is lowered by one step, and as shown by the imaginary line in the third national possession, the outer peripheral part 1a at the free end 3 of the bub.
, lb and the upper surface step of the cylinder wall portion 9, and a bore 19 is correspondingly provided in the peripheral edge portion 18 to allow the boss 16 on the bubble side to pass through.

Therefore, after fitting the peripheral edge 18 of the flange 4 into the step at the free end of the bub and causing the boss 16 to protrude from the bore 19, a jig is placed on the boss and ultrasonically vibrated to crush it and the flange is The work involves clamping the boss between the crushed head and the free end of the bub.

Conventionally, during such vibration machining, cracks often appeared in the central cylindrical portion 8, and dimensional properties such as roundness tended to deteriorate.

After investigating the cause of this, we found that the main cause of this was the non-uniformity of the strength distribution at the free end of the bubble or the large difference in wall thickness.

In the conventional tape reel, first of all, in the cross-sectional view of FIG.
The interior above, ie, the portion surrounded by the imaginary line 20, was solid.

Therefore, this wall thickness was extremely thick compared to other parts.

Second, the upper surface portion 13 starting from the root of the small protrusion 12
and the connecting peripheral portion 21 . with the axial wall portion 14 . The axial wall portion 14 and the connecting peripheral edge portion 22 of the connecting annular portion 15 are both connected linearly, forming a so-called acute angle.

As described above, stress during vibration machining is applied to the acute corner 21.
22, and the mass inside it is significantly different from the mass in other parts, so an equivalent vibration system is created, and the specific frequency during vibration machining is determined by the bond compliance with the mass in other parts. Resonance was likely to occur, and even at the corners 21 and 22, stress concentration sites were generated, causing distortion and cracks.

Therefore, in the present invention, the upper interior 20 of the reel shaft receiving space 10 in the bubble 1 (in the embodiment, the central cylindrical portion 8 to the inner cylindrical portion 7) is formed into a hollow blind hole, and the small protrusion 12 and the upper surface portion 13 are formed into a hollow blind hole.
In the first configuration, the axial wall portion 14 has a wall thickness that is not significantly different from other portions.

In addition, the surface-to-surface connecting portions of each surface of the inner cylinder portion 7, for example 2
1.22 is rounded and connected with a curved surface to eliminate sharp corners.

Furthermore, the connecting portions 23 between the walls of the interior formed by the internal space 20 are also rounded so as not to form acute angles.

The tape knoll manufactured by the present applicant, which has taken the above measures, shows almost no cracking or distortion during vibration, and the stress is evenly distributed. Due to the uniformity of the thickness, we have succeeded in maintaining a sufficiently high roundness of each part as it changes over time.

In order to manufacture even the integral flange 2 with high roundness, the back of the shaft engaging rib 11 should also be thinned out, as disclosed separately by the applicant, although this is slightly different from the purpose of the present invention.

This lightening appears as a depression 24 when viewed from the front.

In addition, since the tape reel having the above-mentioned effects has a homogeneous strength distribution, there is no need to limit the method to ultrasonic welding, and the inner cylindrical portion 7 is the central cylindrical portion. 8 and a cylindrical wall portion 9, the wall portion 14 of the central cylindrical portion is separated from the cylindrical wall portion 9.
The gist of the present invention can be achieved as is if the central cylindrical portion 8 is considered as the outer circumferential surface of the inner cylindrical portion 7 or as the inner cylindrical portion 7 itself.

[Brief Description of the Drawings] Fig. 1 is an exploded perspective view of one embodiment of the tape reel of the present invention, Fig. 2 is a perspective view of a bub and an integral flange seen from the back side, and Fig. 3 is an exploded perspective view of an embodiment of the tape reel of the present invention. FIG. 2 is a sectional view taken along the line III in FIG. In the figure, 1 is a buff, 2 and 4 are flanges, 7 is an inner cylinder part,
12 is a small projection, 13 is an upper surface portion, 14 is an axial wall portion, 20
21, 22, and 23 are hollow portions or spaces, and 21, 22, and 23 are surface-to-plane connection peripheral portions.

Claims (1)

[Claims for Utility Model Registration] A plastic bubble has flanges at both ends, at least one of the flanges is molded as a separate piece that is attached to the corresponding free end of the bubble, and the center of the upper surface of the free end of the bubble has flanges. A small protrusion that engages with the elastic holding piece of the cassette case is provided, and a reel shaft receiving hole that opens at the other end and extends halfway along the axial height toward the free end is provided inside the bubble. A tape reel for a video cassette tape, wherein a portion inside the bubble above the reel shaft receiving space is also hollow and continues into the receiving space up to the inside of the small protrusion, and the small protrusion is A tape reel for a video cassette tape, characterized in that the connection portion between each surface of the supporting upper surface portion and the axial wall surface portion around the upper surface portion is a curved surface.