JPH0519902Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a tape reel for a magnetic tape cassette used in a video tape recorder (VTR) or the like.

[Conventional technology]

Tape reels for magnetic tape cassettes used in VTRs and the like are of the so-called two-piece type, consisting of an upper guide flange and a lower guide flange having a pivot portion integrally formed in the upper center of a central tube. On the other hand, the entire upper guide flange and lower guide flange of the tape reel are usually molded from synthetic resin, but since there is no need to take wear resistance into consideration that much, synthetic resin with particularly excellent wear resistance is not used. Therefore, even if the pivot portion is damaged by wear or the like due to rotation of the tape reel, there is no guarantee.

Therefore, a so-called three-piece type is known, in which a pivot member made of a different material with high wear resistance is separately molded from the lower guide flange, and the pivot member is fitted into the center of the upper part of the central cylinder of the lower guide flange. It is being That is, as shown in FIG. 6, this type of tape reel 1 consists of three pieces: an upper guide flange 2, a lower guide flange 3, and a pivot member 4. The lower guide flange 3 has a tape deck drive shaft ( (not shown), a reel hub 6 for tape winding disposed concentrically with the central cylinder 5 on the outside of the cylinder 5, and a plurality of reel hubs 6 connecting the central cylinder 5 and the reel hubs 6. A connecting rib 7 is integrally molded with the lower guide flange 3, and a fitting part 8 is formed at the center of the upper part of the central cylinder 5. In addition, the diameter of the reel hub 6 and the connecting rib 7 differ between long-time and short-time use.
It is shaped by changing the length of.

The pivot member 4 consists of a base 4a and a pivot shaft 4c that stands up on the upper surface 4b of the base 4a, and the base 4a is fitted into the fitting part 8 of the central cylinder 5. Then, the pivot shaft 4c of the pivot member 4 is made to protrude upward from the through hole 2a of the upper guide flange 2,
An upper guide flange 2 is welded to the upper surface of a central cylinder 5 to form a tape reel 1.

[Problem that the invention attempts to solve]

However, in the above-mentioned pivot member 4, since the gate for resin injection during molding is generally located on the side surface of the base 4a, injection marks of the gate may remain protruding from the side surface of the base 4a, or cavities may be formed. The synthetic resin material may bulge out and adhere to the tip of the gate after injection, and if this continues, the pivot member 4 cannot be fitted into the fitting portion 8 of the central cylinder 5.

Therefore, after molding the product, the base 4 of the pivot member 4
Since it is necessary to perform a cutting operation to remove protrusions such as injection marks protruding from a, a large number of man-hours are required, resulting in poor productivity.

The present invention was developed against the background of the above circumstances, and an object of the present invention is to provide a tape reel for a magnetic tape cassette that can be used with the pivot member left as cast.

[Means for solving problems]

In order to achieve the above object, the present invention provides a tape reel for a magnetic tape cassette in which a fitting part is formed in the upper part of the central cylinder of the tape reel, and the base of a pivot member is fitted into the fitting part. The pivot member is characterized in that a notch is provided on the side surface of the base thereof.

[Effect]

According to the above configuration, if the gate is located in the notch, even if a protrusion such as an injection mark is attached to the outer surface of the notch, the pivot member can be fitted into the fitting part of the central cylinder as it is. Therefore, the protrusion can be arranged in the space between the fitting part and the notch without directionality.

Therefore, the molded pivot member can be used as cast without having to cut off the protrusion, so cutting off work is not necessary, and the number of man-hours can be omitted and productivity can be improved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

The magnetic tape cassette 10 has a cassette main body 1 constructed by combining an upper half 11 and a lower half 12.
Two tape reels 15, 15 for supplying and winding the magnetic tape 14 are rotatably housed in the cassette 3, and the magnetic tape 14 is placed in front of the tape guide portions 13a, 13a of the cassette body 13. It is wound up and a front cover 13b is attached to the front part thereof so that it can be opened and closed.

The tape reel 15 includes an upper guide flange 16 having a through hole 16a in the center, a center tube 17, a reel hub 18 disposed concentrically with the center tube 17 on the outside of the tube 17, and a connection between the center tube 17 and the reel hub 18. The lower guide flange 20 is integrally formed with a plurality of connecting ribs 19, and is pressed by the tip of a plate-shaped reel restraining spring 21 that protrudes upward from the through hole 16a and is interposed between the upper half 11 and the tape reel 15. It is composed of three pieces including a pivot member 22.

The central cylinder 17 has a plurality of engagement ribs 17a on its inner periphery that engage with a drive shaft (not shown) of the tape deck.
The drive shaft fitting recess 17b has a protruding drive shaft fitting recess 17b, and a circular fitting part 23 into which the pivot member 22 is fitted is recessed in the upper part 17c of the central cylinder 17. Further, on the lower surface of the lower guide flange 20, a guide edge 20a that guides the drive shaft of the tape deck into the drive shaft fitting recess 17b and an engagement edge 20b that is loosely fitted into the mounting hole of the cassette body 13 are protruded concentrically. has been done.

The upper guide flange 16 has a flange portion 16b.
A protrusion 16c is provided in the center of the projecting part 16c, and a through hole 16a is provided in the center of the protrusion 16c.
The center cylinder 17 of the lower guide flange 20 is located on the lower surface of the lower guide flange 20.
A welding protrusion 16d is protrudingly provided to be welded to the upper part 17c.

The pivot member 22 has both guide flanges 1
The upper guide flange 1 is molded from a hard synthetic resin material that has better wear resistance than 6 and 20.
a pivot shaft 22 that protrudes upward from the through hole 16a of No. 6 and is pressed by the reel holding spring 21;
a, and a base portion 22b that is fitted into the fitting portion 23 of the central cylinder 17.

The pivot shaft 22a is formed into a conical shape with a rounded tip, and the base 22b has a groove 22c formed in the upper surface surrounding the pivot shaft 22a, and a tapered surface 22d formed in the lower edge. Furthermore, a planar notch 22e is formed in a part of the side surface.

When the pivot member 22 formed as described above is attached to the lower guide flange 20 by fitting the base portion 22b into the fitting portion 23 of the central cylinder 17, there is a gap between the notch portion 22e and the fitting portion 23. A half-moon-shaped space 24 is formed.

As shown in FIG. 4, the tip of a tunnel gate 30 that serves as an inlet for synthetic resin material for molding the pivot member 22 is located in the notch 22e, and this gate 30 is inserted into the movable mold 31. The other end of the tunnel gate 30, which is provided in an oblique direction and opens on the top surface, is connected to a runner 33 that is recessed in the bottom surface of the fixed mold 32.

A solution of a synthetic resin material for molding the pivot member 22 is injected from the tip of the gate 30 through a runner 33 into a cavity 34 defined by a movable mold 31 and a fixed mold 32.

In addition, injection marks may remain on the molded pivot member 22 at the portion where it connects with the tip of the gate 30, or injection marks may remain protruding from the tip of the gate 30 even after filling the cavity 34. Extra protrusion D on the outside of the product due to adhesion of resin material
However, in this embodiment, the gate 30 is located in the planar notch 22e formed in the base 22b, so in this case, the protrusion D is not formed in the notch 22e. Formed protrudingly.

Then, when the pivot member 22 with the protrusion D still attached is fitted into the fitting part 23 of the central cylinder 17,
Since the space 24 is formed between the notch 22e and the fitting part 23 as described above, the protrusion D is freely disposed in this space 24 without any directionality, and the protrusion D is located at the base of the pivot member 22. 22b can be fitted in a normal state without being hindered by the peripheral wall of the fitting part 23.

Therefore, the pivot member 22 can no longer be fitted due to the protrusion D or be fitted at an angle, as in the conventional case.
Since the functions of the tape reel 15 can be fully exhibited, the product accuracy of the tape reel 15 can be improved.

In addition, the pivot member 22 can be used as cast without cutting off the protrusion D, which eliminates product defects due to molding, eliminates the need for post-processing such as cutting off, and saves man-hours and reduces product costs. This can be reduced.

Note that the notch at the base of the pivot member of the present invention is not limited to the above-mentioned embodiments, and may have a shape other than a planar shape as long as it forms a space in which a protrusion can be placed between it and the fitting part. Other shapes are also acceptable.

[Effect of idea]

As explained above, the tape reel of this invention has
A fitting part is formed in the upper part of the central cylinder, and a notch part is provided on the side surface of the base of the pivot member to be fitted into the fitting part, and when the pivot member is fitted into the fitting part, the notch part and the pivot member are fitted into the fitting part. Since a space is formed between the fitting part and the notch, a gate made of synthetic resin material is placed in this notch.
Even if a protrusion such as an injection mark is attached to the notch, the protrusion is placed in the space between the fitting part and the pivot member when the pivot member is fitted, so the pivot member can be attached to the as-cast part. can be used as is, and the work of cutting off protrusions such as injection marks, which was required in the past, can be omitted, improving productivity and reducing product costs.

Furthermore, product defects due to assembly are eliminated,
The precision of the tape reel can be improved.

[Brief explanation of the drawing]

1 to 5 show one embodiment of the present invention, in which FIG. 1 is a perspective view of a pivot member, FIG. 2 is a plan view of a magnetic tape cassette with a portion of the upper half cut away, and FIG. The figure is a vertical cross-sectional view of the main parts of the tape reel.
FIG. 4 is a longitudinal sectional view showing the molded state of the pivot member, FIG. 5 is a plan view of the pivot member fitted into the fitting portion, and FIG. 6 is a longitudinal sectional view of the main part of a conventional tape reel. 10... Magnetic tape cassette, 15... Tape reel, 16... Upper guide flange, 17...
Central tube, 18... Reel hub, 20... Lower guide flange, 22... Pivot member, 22a...
Pivot shaft, 22b... Base, 22e... Notch, 23... Fitting part, 24... Space, 30...
Tunnel gate, 31...Movable type, 32...Fixed type, D...Protrusion part.

Claims (1)

[Scope of utility model registration request] In a tape reel of a magnetic tape cassette, a fitting part is formed in the upper part of the central cylinder of the tape reel, and a base part of a pivot member is fitted into the fitting part,
A tape reel for a magnetic tape cassette, wherein the pivot member is provided with a notch on a side surface of its base.