JPH0258710B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a tape winding hub that is incorporated into a cartridge case. The purpose of the present invention is to obtain a high-precision hub that does not cause any turbulence and has good roundness and perpendicularity.

[Conventional technology]

For example, a tape cartridge as shown in FIG. 1 has drive shaft insertion holes 2, 2 vertically penetratingly provided on the left and right sides of the center of a cartridge case 1, and a pair of drive shaft insertion holes 2, 2 to be wound on the left and right sides of the inside of the case 1. Plastic hubs 4, 4 are rotatably arranged, and the tape 3 is led out from one hub 4 to the front of the case and wound around the other hub 4. This form is substantially the same in ultra-small tape cartridges, so-called microcassettes, and in particular, the hub 4 is similar both in function and form.

The hub 4 used therein has a hub hole 5 in the center that penetrates in the vertical direction, and a total of six hub claws 6 are spaced at equal intervals on the inner peripheral surface of the hub hole 5. A clamp hole 8 is recessed in one place of the circular outer peripheral side surface 16 in the vertical and width directions, and an elastically deformable plastic clamp piece 9 is inserted into the clamp hole 8 by attaching the tape 3 to the clamp hole 8.
The hub 4 is press-fitted from the radial direction by sandwiching the end of the hub 4 (specifically, the end of the leader tape).
The ends of the tape are connected to each other by locking.

However, although the hub 4 has a hub hole 5 in the center, it is a solid body that is considerably thick in the radial direction and the vertical and width directions. Moreover, since it has a hub pawl 6 and a clamp hole 8, the wall thickness in the radial direction is not necessarily uniform.
Nevertheless, conventional hubs 4 have been integrally molded from plastic.

[Problem to be solved by the invention]

As a result, the circular outer circumferential side surface 16 of the hub 4 is deformed by heat shrinkage during mold molding, so-called sink marks (often in the shape of a hollow in the vertical and width directions), and the roundness of the hub outer circumferential side surface 16, especially the verticality. If the tape 3 is left wrapped in layers around the outer circumferential side surface 16 and left unsecured, the tape 3 will be deformed to match the shape of the outer circumferential side surface 16, causing instability in tape running. This has an adverse effect on track deviation and other electromagnetic conversion characteristics.

In addition, in a tape cartridge such as the illustrated example in which the A side and the B side are used upside down,
As a whole, the top and bottom are the same shape, and the left and right are symmetrical, so when playing on sides A and B, you can check the feeding side hub 4 and the winding side hub 4, and check the amount of tape wound on each hub 4 left and right. The hub 4 that is visible through the drive shaft insertion hole 2 and the transparent window 10 attracts considerable attention. No, the conventional hub 4 is supposed to call attention to the user, but since these are integrally molded at the same time, the color that is most effective for calling attention is not the same. There was room for improvement in this respect as well. Although it would be possible to make color prints or paste printed films on appropriate locations on the hub 4 as a makeshift measure, such makeshift means would cause discoloration, peeling, etc., and would not be suitable for actual use in terms of appearance and performance. I don't.

[Means to solve the problem]

As a result of repeated discussions and studies on how to solve the various problems of the conventional art, the inventors of the present invention discovered that the inner and outer parts of the hub 4, that is, the central part of the hub 4 and the outermost circumference of the hub 4, By separately molding and integrating the outermost peripheral portion of the hub 4, the outermost peripheral portion of the hub 4 can be made as thin as possible in the radial direction over the entire circumference, so that the roundness of the hub outer peripheral side surface 16 and He realized that verticality could be well ensured, and finally completed a hub structure that embodies this, leading him to propose the present invention.

Incidentally, in standard video tape cartridges, a flanged tape reel with flanges above and below the hub is installed inside the cartridge case, but whether the tape reel is a single flange type or a double flange type. Well, it is also possible to mold the hub and then integrally join the separate flanges by ultrasonic welding, or, as will be described later, after primary molding the hub inner ring, it is possible to include the flange on the outer periphery of the inner ring. It should be added that since it is also possible to secondarily mold the hub outer ring body, the present invention also extends to the molding of such a flanged tape reel.

〔Example〕

Hub Structure Next, the structure of the hub 4 obtained by the present invention will be explained first. In FIGS. 2 to 6, each hub 4 has a relatively thick wall that constitutes the main body of the central portion. It consists of an inner ring body 11 and a thin outer ring body 12 which is integrally connected to the outer periphery of the inner ring body 11 and constitutes the outermost periphery of the hub 4. The inner ring body 11 has the hub hole 5 and the hub pawl 6 in the center, and has a recess 14 at one location on the substantially circular outer circumferential side surface 13. The outer ring body 12 is connected to the flesh wall part 15 of the clamp hole 8 which is fitted into the recess 14 of the inner ring body 11, and is connected to the flesh wall part 15, and the outer peripheral side surface 16 is formed into a perfectly circular vertical surface. 11 and a ring portion 17 connected to the outer circumferential side surface 13 of 11. In FIG. 2, the dotted portion indicates the outer ring body 12.

The inner ring body 11 and the outer ring body 12 are made of different colored but preferably identical plastic materials, for example polyacetal resin, by a two-color molding method. That is,
After primary molding of the inner ring body 11, the outer ring body 12 is secondarily molded around the outer circumference of the inner ring body 11, using the inner ring body 11 as a core.
The inner ring body 11 and the outer ring body 12 are fused and integrated at the boundary line. The specific mold structure and molding method will be described later.

If the ring part 17 of the outer ring body 12 is too thick, the outer peripheral side surface 1
6, and if it is too thin, it will be affected by the sink marks generated on the inner ring 11. Therefore, the radial thickness t of the ring 17 is 0.1 mm to 5 mm, preferably 0.5 to 2.5 mm, and more specifically, Approximately 1.0 mm is preferable. In FIGS. 2 and 3, stepped surfaces 19, 19 are formed on the upper and lower end surfaces of the inner ring body 11 inwardly from the outer circumferential side surface 13 at the quartering points of the outer circumference, and the outer ring body 12
The ring portion 17 has flanges 20, 2 facing inward from the upper and lower ends of the inner periphery at respective positions corresponding to the formation positions of the stepped surface 19.
0 are connected in series, and the upper and lower flanges 20, 20 are connected to the stepped surfaces 19, 19 in a wrap-around manner at four locations, thereby preventing the inner ring body 11 and the outer ring body 12 from shifting in position, especially in the vertical direction. ing. In addition, arcuate grooves 21 are formed at appropriate intervals on the outer circumferential side surface 13 of the inner ring body 11 in the vertical and widthwise directions, and on the inner circumferential surface of the outer ring body 12, the grooves 21 are tightly fitted. The connecting protrusions 22 are provided to protrude in the longitudinal direction, and due to the radial biting action of these grooves 21 and the protrusions 22, the outer ring body 12 is lifted off from the inner ring body 11 during and after molding, and the hub outer peripheral side surface 16 This prevents deformation and irregularity of roundness. Since the protrusion 22 has a constricted base end, it is possible to effectively prevent sink marks from occurring on the outer circumferential side surface of the area where the protrusion 22 is present.

Further, a dovetail groove 23 is formed in the inner bottom surface of the recess 14 of the inner ring body 11 in the vertical width direction, and a part 24 of the clamp hole wall part 15 of the outer ring body 12 is inserted into the dovetail groove 23 during molding. It is designed to be connected in a tight fit state, and prevents the wall portion 15 of the clamp hole 8 from floating away in the radial direction. During plastic molding, sink marks and gate marks are likely to appear near the injection gate, so the injection gate P when molding the outer ring body 12 is set at the inner bottom of the clamp hole 8.

Method for Molding Hub Next, a method for specifically molding the hub 4 having the above structure will be described with reference to FIGS. 7 to 12.

Figures 7 to 9 show the primary forming process of the inner ring body 11, and Figures 10 to 12 show the outer ring body 12.
This shows the secondary forming process. The mold is equipped with a total of four ejector pins 26, and the inner ring body 1
First, inserts 2 for forming each lower surface of the outer ring body 12
A lower movable mold 30 consisting of 7, 28, 29;
An inner ring consisting of inserts 32, 33, and 34, which is provided with ejecting pins 31 facing each pin 26 of the movable mold 30 and molds the outer peripheral surface (including the recess 14 and the outer peripheral side surface 13) and the upper surface of the inner ring body 11. The outer ring body 1 is provided with an upper mold 35 for molding the body and ejecting pins 36 facing each pin 26 of the movable mold 30.
2 (including clamp hole 7 and outer peripheral side surface 16)
Inserts 37, 38, which mold the outer peripheral surface and the upper surface.
An upper mold 40 for molding an outer ring body consisting of 39 is prepared. The movable mold 30 rotates on a horizontal plane, and the upper mold 35 for molding the inner ring body and the upper mold 40 for molding the outer ring body are disposed at separate positions.

In FIG. 7, first, the movable mold 30 and the upper mold 35 for molding the inner ring body are combined, and both molds 30,
A plastic material (for example, white) is injected into the inner ring body 11 to form the primary molding. At this time, each ejecting pin 26, 31 equipped on both molds 30, 35
are vertically opposed to each other, and stepped surfaces 19, 19 are formed at the positions of the outer periphery quarters of the upper and lower end surfaces of the inner ring body 11 by the protruding end surfaces of these ejecting pins 26, 31, respectively.
form the top and bottom.

In FIG. 8, after the inner ring body 11 is cooled and solidified in both molds 30 and 35 to the extent that it can be ejected, both molds 30 and 35 are opened. At this time, each ejecting pin 31 on the upper mold 35 side The inner ring body 11, which has been primarily formed by protruding downward from the upper mold 35, is transferred to the moving mold 3.
Separate together with 0.

Next, as shown in FIG. 9, after separating the movable mold 30 from the upper mold 35, without protruding the inner ring body 11 onto the movable mold 30 (the sprue runner of the plastic material for primary molding does protrude), Moving mold 30
Rotate the chisel.

In FIG. 10, the movable mold 30 supporting the inner ring body 11 is rotated and positioned directly below the upper mold 40 for molding the outer ring body, and then the movable mold 30 and the upper mold 40 are combined, and the movable mold Each ejector pin 26 on the 30 side is slightly sunk downward. The ejecting pins 36 on the upper mold 40 side, which are opposite to the pins 26, are also set slightly apart from the stepped surfaces 19 on the upper end surface of the inner ring body 11. Thus both molds 3
A plastic material (for example, yellow) for secondary molding is injected into the inner ring 11 as a core, and an outer ring 12 is second formed around the outer periphery of the inner ring 11. At this time,
At the same time, the flanges 20 are extended inwardly from the upper and lower ends of the inner circumferential surface of the outer ring body 12 and connected to each stepped surface 19 of the inner ring body 11 in a wrap-around manner by the protruding end surfaces of the upper and lower ejecting pins 26 and 36. molded.

In FIG. 11, after the outer ring body 12 is solidified in both molds 30 and 40, both molds 30 and 40 are opened. At this time, each ejecting pin 36 on the upper mold 40 side
is projected downward to separate the product hub 4 after secondary molding from the upper mold 40 together with the movable mold 30.

Next, as shown in FIG. 12, the product hub 4 is ejected from the movable mold 30 using the ejector pin 26 equipped thereon, and the sprue runner of the plastic material for secondary molding is also ejected at the same time.

Thereafter, the movable mold 30 rotates and is positioned directly below the upper mold 35 for forming the inner ring body, returning to the original state shown in FIG. 7. By repeating this series of operations, it is possible to continuously form two-color molded hubs. When the above-described molding method is used, it has become possible to manufacture a hub 4 whose front and back sides are exactly the same in shape, including the ejector pin marks.

Further, FIG. 13 shows another modification of the hub 4 obtained by the method of the present invention, which corresponds to the above-mentioned FIG. In order to more effectively prevent floating in the radial direction, a through hole 43 is provided between the upper and lower stepped surfaces 19, 19 of the inner ring body 11, and a plastic material for molding the outer ring body 12 is inserted into the through hole 42. is starting to go around. However, based on the same purpose, recesses 44, 44 are formed in the upper and lower stepped surfaces 19, 19 as shown in FIG. 14 to improve the engagement with the collar 20, which is connected to the stepped surfaces 19 in a wrap-around manner. You can do it like this.

In addition, it is preferable that the inner ring body 11 and the outer ring body 12 be molded from the same plastic material with different colors.
Both 11 and 12 may be the same color. When using different plastic materials, e.g. polyacetal resin and acrylonitrile-butadiene-
It is conceivable to combine it with a styrene copolymer resin. Furthermore, it goes without saying that the movable mold 30 may be one that moves back and forth in a straight line on a horizontal plane.

〔effect〕

As explained above, in this invention, the inner ring body 1
1 is first formed, and then the outer ring body 12 is second formed around the outer circumference of the inner ring body 11 into a thin, almost uniform shape over the entire circumference, so that the resulting product hub 4 is a thick inner ring. Even if sink marks occur on the outer peripheral side surface 13 of the body 11 during primary molding, the sink marks can be removed by removing the sink marks from the outer ring body 12.
This will be absorbed during secondary molding, and the roundness and perpendicularity of the hub outer circumferential side surface 16 can be effectively and reliably ensured. Therefore, the tape 3 can be neatly wound around the outer circumferential side surface 16 of the hub without any residual deformation, and the electromagnetic conversion characteristics can be improved. In particular, since the outer circumferential side surface 16 of this type of hub 4 almost entirely serves as a winding surface for the magnetic tape, the upper and lower center portions of the outer circumferential side surface 16 as well as the upper and lower end portions are covered during molding. If sink marks occur, the tape edges may become deformed, tape running becomes unstable,
This causes track deviation and other adverse effects on other electromagnetic conversion characteristics. However, in the hub according to the present invention, stepped surfaces 19, 19 are formed only at the outer end portions of the upper and lower end surfaces of the inner ring body 11, and the stepped surfaces 1
9, 19 only, the upper and lower collars 20, 20 of the outer ring body 12
The inner ring body 11 and the outer ring body 12 are integrally connected by going around the inner ring body 11 and the outer ring body 12. Therefore, due to the presence of the stepped surface 19 and the collar 20, it is possible to reliably prevent the inner ring body 11 and the outer ring body 12 from shifting vertically even when subjected to a drop impact, etc., and also to prevent the inner ring body 1
Since the amount of wrap around of the collar 20 relative to the end face of the outer ring body 12 can be reduced only at the outer end portion as shown in FIG. Therefore, the perpendicularity and roundness over the entire circumference of the hub outer circumferential side surface 16 can be ensured with extremely high accuracy between the upper and lower sides. In addition, as described above, the flange 20 formed on the outer ring body 12 is coupled to the stepped surfaces 19 discontinuously formed at approximately equal intervals on the outer ends of the upper and lower end faces of the inner ring body 11 in a wrap-around manner, so that the inner ring body 11 and the outer ring Since the distance between the joints of the bodies 12 can be kept constant, the contractile force of the outer ring body 12 can be equally divided, and the hub can be formed with high roundness.

In addition, since the inner ring body 11 and the outer ring body 12 are molded in two steps, it is easy to make both 11 and 12 different colors if necessary. This comparison inevitably draws the attention of the viewer, and is useful for determining the relative positional relationship between the feeding-side hub 4 and the winding-side hub 4 in a tape cartridge as shown in the illustrated example, which is used upside down. valid and each hub 4
It is convenient for visually confirming the direction of rotation, and has a great design effect.

[Brief explanation of the drawing]

FIG. 1 is an external perspective view generally illustrating a tape cartridge. 2 to 6 show the structure of the hub obtained by the present invention, in which FIG. 2 is a plan view, FIG. 3 is a sectional view taken along line A-A in FIG. 2, and FIG. 2 is a sectional view taken along the line B-B in FIG. 2, FIG. 5 is a plan view of the inner ring body forming the hub, and FIG. 6 is a plan view of the outer ring body forming the hub. 7 to 12 are cross-sectional views showing the mold structure and its operation for implementing the present invention, and FIGS.
The figures up to the figures sequentially show the primary forming process of the inner ring body constituting the hub, and FIGS. 10 to 12 sequentially show the secondary forming process of the outer ring body forming the hub. FIGS. 13 and 14 are sectional views corresponding to FIG. 4, showing different modifications of the hub obtained by the present invention. 1... Cartridge case, 3... Tape, 4
...Hub, 5...Hub hole, 6...Hub pawl, 8...
Clamp hole, 9... Clamp piece, 11... Inner ring body, 12... Outer ring body, 13... Outer peripheral side of inner ring body, 14... Recess in inner ring body, 15... Flesh wall of clamp hole, 16... ...Outer peripheral side surface of outer ring body, 17...
Ring part of outer ring body, 19...Stepped surface on inner ring body side, 20
...The tsuba on the outer ring body side.

Claims (1)

[Claims] 1 A thick inner ring body 11 having a hub hole 5 in the center and a hub pawl 6 protruding from the inner peripheral surface of the hub hole 5, and a substantially circular outer peripheral side surface 13; The stepped surfaces 19, 19 are discontinuously formed on the outer ends of the upper and lower end surfaces of the inner ring body 11 at approximately equal intervals, and flanges 20, 20 are formed on the upper and lower inner periphery ends of the outer ring body 12. A hub for tape cartridges connected in a wrap-around manner.