JPH0447832Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a reel for winding magnetic tape.
More specifically, the present invention relates to a magnetic tape reel with an improved hub constituting the reel.

[Prior Art] A reel for winding magnetic tape used in audio, video, computers, etc. has a hub that serves as the winding surface of the magnetic tape, and a reel on both sides of the hub to regulate both edges of the wound magnetic tape. It consists of a pair of flanges. The hub includes an inner cylinder having a hole into which a reel shaft of a recording/reproducing device is inserted, and an outer cylinder around which a magnetic tape is wound, which are integrally molded from a plastic resin such as ABS.

Figure 3 is a plan view of a conventional 1-inch hub.
FIG. 4 is a sectional view taken along the line AA in FIG. 3.

The hub 1 is an integrally molded product having an inner tube 2 and an outer tube 3, and the inner tube 2 is formed with a hole 4 into which a reel shaft of a recording/reproducing device is inserted. A groove 5 is formed in a substantially annular shape between the inner cylinder 2 and the outer cylinder 3.
Ribs 8 are provided within the groove 5 at equal intervals, defining the groove 5 to a predetermined length. The length of the outer cylinder 3 in the axial direction is shorter than the inner cylinder 2 by a length d at both ends thereof, and the outer cylinder 3 and the inner cylinder 2 are formed with a step. A pair of flanges 6 are fitted to both ends of the inner cylinder 2 and fixed with screws or the like to form a magnetic tape reel.

In order for the reel to be rotationally driven by the reel shaft, locking grooves 7 are formed at equal intervals on the inner peripheral surface of the inner cylinder 2.
A locking member protruding from the reel shaft enters the locking groove 7 and rotates the reel while locking the hub 1. Therefore, the inner cylinder 2
is thick so that the locking groove 7 can be formed,
On the other hand, the outer cylinder 3 only serves as a magnetic tape winding surface and a fixing surface for the flange 6, and does not directly receive the rotational driving force from the reel shaft, so the inner cylinder 2
It is molded thinner than the

However, such a large hub 1 with a diameter of 1 inch or more does not shrink uniformly after injection molding compared to a hub used for a compact cassette, etc., and especially the rib 8 which is the thickest part of the hub 1 The area near it solidifies last. This causes a problem that sink marks occur on the outer peripheral surface of the portion of the outer cylinder 3 having the ribs 8 and are recessed inward in the radial direction, making the peripheral surface of the outer cylinder 3 uneven. In addition, the cooling rate differs due to the difference in wall thickness between the inner cylinder 2 and the outer cylinder 3, and axial twist occurs between the inner cylinder 2 and the outer cylinder 3, causing the flange fixing surface of the outer cylinder 3 to become corrugated. When the flange 6 is fitted into the inner cylinder 2, the outer cylinder 3 and the flange 6 do not come into close contact with each other, and the flange 6
There is a problem in that it cannot be fixed perpendicularly to the outer cylinder 3. Therefore, even if magnetic tape is wound on a reel that has undergone such deformation, the magnetic tape will not be wound evenly, and the flange 6 will damage the tape side edge when unwinding and unwinding. The reel was extremely unreliable.

[Purpose of the invention] The purpose of the invention is to solve the above-mentioned conventional problems, and to provide a magnetic tape with a structure that prevents deformation after injection molding and ensures reliable winding and feeding of the magnetic tape. Our goal is to provide reels.

[Structure of the invention] The above object of the invention consists of a hub having an inner cylinder into which a reel shaft is inserted and an outer cylinder around which a magnetic tape is wound, and a pair of flanges provided on both sides of the hub. In the magnetic tape reel, the outer cylinder, which defines circumferential grooves at equal intervals between the inner cylinder and the outer cylinder, becomes thicker from both ends of the grooves toward the center, and This is achieved by a magnetic tape reel characterized in that the wall thickness is equal to that of the inner cylinder.

That is, since the outer cylinder has a thick wall portion that protrudes toward the center of the groove, the cooling rate of the outer cylinder is slowed down, and is cooled at approximately the same rate as the cooling rate of the inner cylinder. Deformation of the hub is thus prevented and reliable magnetic tape winding, take-up and delivery is ensured.

[Embodiments] The embodiments of the present invention will be described below based on the accompanying drawings.

FIG. 1 is a plan view of a hub of a magnetic tape reel, and FIG. 2 is a sectional view taken along line BB in FIG.

The hub 1 consists of an inner cylinder 2 and an outer cylinder 3, for example.
It is integrally molded by injection molding of plastic resin such as ABS. The inner cylinder 2 has a hole 4 into which a reel shaft of a recording/reproducing device is inserted, and a locking groove 7 into which a locking member of the reel shaft is inserted. The outer cylinder 3 is formed with a step difference from the inner cylinder 2, and is formed to be shorter by a length d than the inner cylinder 2 at both ends in the axial direction, and a pair of flanges 6 are fitted to both ends of the inner cylinder 2. It is fixed to the outer cylinder 3 with screws or the like.

A groove 5 is formed in a substantially annular shape between the outer cylinder 3 and the inner cylinder 2, and ribs 8 are provided at equal intervals within the groove 5, defining the groove 5 to a predetermined length. are doing.
The outer cylinder 3 defining the grooves 5 becomes thicker from both sides of each groove 5 toward the center, and is formed to have the same thickness as the inner cylinder 2 at the center of the groove 5. That is, the wall thickness of the outer cylinder 3 at both ends of the groove 5 is thin and is the minimum thickness part of the outer cylinder 3, and the wall thickness of all other parts is thicker than the outer cylinder wall thickness at both ends of the groove 5.

After injection molding, the hub 1 is cooled and solidified, but the area around the rib 8 of the outer cylinder 3 is slowly cooled. Further, since the outer cylinder 3 between the ribs 8 is thicker toward the middle portion in the circumferential direction, the cooling rate becomes slower as the thickness increases. Therefore, the portions of the outer cylinder 3 near the ribs 8 and between the ribs 8 are cooled in relatively approximately the same amount of time. Furthermore, since the central portion of the outer cylinder 3 between the ribs 8 has the same wall thickness as the inner cylinder 2, it is cooled in approximately the same time as the inner cylinder 2. Therefore, the outer cylinder 3 is cooled uniformly in the circumferential direction, no sink marks occur on the outer peripheral surface of the rib 8, and since the outer cylinder 3 and the inner cylinder 2 solidify almost simultaneously, the outer cylinder 3 and the inner cylinder 2 The two sides will not be twisted with respect to each other, and both side surfaces of the outer cylinder 3, which are the flange fixing surfaces, will not have a wave shape.

Since the inner cylinder 2 and outer cylinder 3 of the hub 1 contract uniformly, deformation is prevented, and the flanges can be fixed in alignment, and the tape winding surface is flat, so the magnetic tape can be wound well. can do.

[Effects of the invention] According to the invention, since the outer cylinder of the hub is thick from both ends toward the center of the portion defining the groove, the outer cylinder is cooled uniformly in the circumferential direction after injection molding. The material shrinks to ensure a flat surface with no sink marks on the outer circumferential surface or both side surfaces. In addition, since the wall thickness of the outer cylinder at the middle of each groove is equal to the wall thickness of the inner cylinder, the outer cylinder and the inner cylinder contract without twisting, and the flange is brought into close contact with the outer cylinder and the inner cylinder, and the tape is wound. It can be fixed perpendicular to the rotational surface. Therefore, damage to the magnetic tape during winding and unwinding is prevented, and good winding of the magnetic tape is ensured.

[Brief explanation of the drawing]

1 and 2 are a plan view and a sectional view of a hub of a magnetic tape reel according to the present invention, and FIGS. 3 and 4 are a plan view and a sectional view of a conventional hub. Codes in the figure: 1...Hub, 2...Inner cylinder, 3...Outer cylinder, 4...Hole, 5...Groove, 6...Flange, 7...
...Latching groove, 8...rib.

Claims (1)

[Scope of utility model registration request] A magnetic tape reel consisting of a hub having an inner cylinder into which a reel shaft is inserted and an outer cylinder around which a magnetic tape is wound, and a pair of flanges provided on both sides of the hub. The wall thickness of the outer cylinder defining circumferential grooves at equal intervals becomes thicker from both ends of the groove toward the center, and is configured to be equal to the wall thickness of the inner cylinder at the center. A magnetic tape reel with special features.