JPH0664889B2 - Hub for tape cassette and manufacturing method thereof - Google Patents

Description

The present invention relates to a tape cassette hub and a manufacturing method thereof.

[Conventional technology]

A pair of hubs is rotatably arranged in a tape cassette for housing the magnetic tape, and a magnetic tape (not shown; hereinafter also simply referred to as “tape”) is wound around the hubs. Has become. Although such a hub is molded from synthetic resin, in the conventional manufacturing method, the hub is generally molded integrally, so that a so-called “sink” occurs at a portion where the wall thickness is relatively large, and as a result, the hub outer peripheral surface is formed. The roundness and verticality of can not be secured. If the tape is wound around the outer peripheral surface of such a hub in a layered state and left unattended, the tape may be bent along the shape of the outer peripheral surface of the hub, the tape running becomes unstable, and the sound quality is deteriorated during recording and reproduction. It can also cause

Attempting to eliminate such defects in hub molding,
For example, as disclosed in Japanese Patent Laid-Open No. 59-110080, there has been proposed a manufacturing method in which a hub is molded by a method other than integral molding. In this manufacturing method, as shown in FIG. 5, the hub 1 is divided into an inner ring body 2 and an outer ring body 3 and individually molded. Then, a step (groove) 4 is formed in the outer ring body 3 as a means for integrally connecting the two and 3, and the inner ring body 2 is formed in this step.
Of the outer ring 5 of the inner ring 2 to increase friction by fitting the ridge 7 of the inner ring 2 or the outer ring 5 of the inner ring 2 as shown in FIG. I am trying to prevent the gap. Incidentally, 6 is a locking claw.

Next, a method of manufacturing the conventional hub 1 will be described with reference to FIGS. 7 to 10. 7 to 10 are sectional views in each step of the mold 10 for manufacturing the hub 1.
As shown in these figures, mold 10 is roughly divided into moving mold 1
It is composed of a primary molding upper die 12 and a secondary molding upper die 13. Then, the moving mold 11 includes the upper and lower molds 12 and
It is capable of reciprocating between 13 lower positions.
An insert 21 is provided at the center of the movable die 11, and a penetrating pin 15 and a projecting pin 16 are alternately arranged on the outer side in the radial direction thereof, and further, on the outer side in the radial direction of the inner ring body 2. A sleeve 17 for forming the protrusion 7 and the outer race 3 is provided. Further, a nest 21 is provided in the center of the upper die 12 for primary molding.
Is arranged, a cavity (mold body) 24 for molding the inner ring body is arranged on the outer side in the radial direction, and a sleeve 18 for forming the protrusion 7 of the inner ring body 2 is further provided on the outer side thereof. .

The upper die 12 for primary molding and the movable die 11 having the above construction are
Combined as shown, the space between both dies 11 and 12 (2 in FIG. 8)
The molten synthetic resin is injected into 5) and then cooled to form the inner race 2 having the ridges 7 on the outer peripheral surface. After the inner race 2 is cooled and solidified, the movable mold 11 is moved in the arrow Y direction and the upper mold 12 is moved in the arrow X direction to open both molds 11 and 12 as shown in FIG. At this time, due to the resistance between the inner ring body 2 and the plurality of penetrating pins 15, the inner ring body 2 is moved to the upper mold 13 for secondary molding together while being attached to the movable mold 11 to carry out the secondary molding process. Move on to.

As shown in FIG. 9, the secondary molding upper die 13 has a nest 23 arranged in the center thereof, a cavity (die body) 26 on the outer side in the radial direction, and an outer ring on the outer side thereof. A sleeve 19 for body shaping is provided. At this time, the moving mold
The sleeve 17 on the eleventh side is separated from the inner ring body 2 and moved slightly downward to form the outer ring body 3. In this state, the molten synthetic resin is injected into both spaces. At the time of this secondary molding, the inner ring body 2 is positioned by a plurality of penetrating pins 15, the outer peripheral portion of which serves as a mold, and is relatively shaped along the outer peripheral portion (protrusion 7) of the inner ring body 2. A thin outer ring body 3 is formed.

In this way, the hub 1 including the inner ring body 2 and the outer ring body 3
After the hub 1 is cooled and solidified, the moving die 11 is moved to the arrow Y
Direction, the upper mold 13 is moved in the direction of arrow X to open both molds 11 and 13 as shown in FIG. Also at this time, the hub 1 is attached to the moving mold 11 and the molds 11 and 13 are separated from each other by the resistance between the inner race 2 and the plurality of penetration pins 15. Then, when the upper die 13 rises to a predetermined position, the moving die
By projecting all the projecting pins 16 from the 11 side at the same time, the hub 1 is separated from the moving mold 11, and the projecting arm (not shown) is moved in the arrow Z direction, and then all projecting pins 16 are pulled. Then, the movable die 11 is moved to a position below the primary molding die 12 shown in FIGS. 7 and 8 to prepare for the next primary molding. By repeating such a series of operations, the hub 1 including the inner ring body 2 and the outer ring body 3 is continuously mass-produced.

The rough surface of the inner ring body 2 in the hub 1'shown in FIG. 6 is realized by, for example, forming a rough inner surface portion of the upper die 12 facing the outer peripheral surface 5 of the inner ring body 2. .
In FIGS. 8 and 10, the same components as those in FIGS. 7 and 9 are designated by the same reference numerals, and detailed description thereof will be omitted.

[Problems to be Solved by the Invention]

In the above-mentioned conventional manufacturing method, two molds, that is, the upper mold 12 for molding the inner ring body and the upper mold 13 for molding the outer ring body are required. Therefore, the structure of the manufacturing apparatus as a whole becomes complicated and expensive. ,
Since the moving mold 11 is moved between the upper and lower molds 12 and 13, there is also a drawback that time efficiency is poor. Further, as shown in FIG. 6, by making the outer peripheral surface 5 of the inner race 2 rough, both races 2,
In the manufacturing method of the hub 1'which has no relative displacement in the axial direction of 3,
There is a problem that when the inner ring body 2 is released from the upper die 12 after being solidified by injection and solidification, it tends to cause a problem, and if the release is improved, the effect of preventing the axial displacement is reduced. It was

[Means for Solving the Problems]

According to the present invention, by injecting the molding resin for the inner ring body before the molding resin for the outer ring body is cooled and solidified, at least a part of the outer peripheral portion of the inner ring body is formed with the infiltration part formed in the outer ring body. By providing a hub for a tape cassette in which the inner ring body is fitted and fixed to the outer ring body by the penetration part and a manufacturing method thereof, the above problems are solved.

〔Example〕

The tape cassette hub and the manufacturing method thereof according to the present invention will be described with reference to FIG. 1 and subsequent drawings. FIG. 1 is a plan view of a tape cassette hub 30 of the present invention, and FIG. 2 is a sectional view taken along one-dot chain line AA in FIG. As shown in these drawings, the hub 30 of the present invention is roughly divided into an inner ring body 32 having a locking claw 6 and a notch 8 for locking the tape end formed on a part of the outer peripheral surface thereof. It consists of an outer ring 33.
Reference numeral 34 denotes an intruding portion integrally formed with the inner ring body 32. By forming this intruding portion 34 on the outer ring body 33 side by several mm, the relative position between the inner ring body 32 and the outer ring body 33 is formed. The displacement is completely prevented not only in the axial direction but also in all directions. As described above, the hub 30 of the present invention is composed of the inner ring body 32 and the outer ring body 33 in that the conventional hubs 1 and 1'shown in the fifth and sixth illustrations.
The same applies to the fact that this does not cause "sinking" at the time of molding, but not only that, but it is possible to completely prevent relative positional deviation between the inner ring body 32 and the outer ring body 33. As described in, the manufacturing apparatus is simplified and the time efficiency is improved.

The biggest difference between the molding die 20 for the hub 30 of the present invention and the conventional die 10 shown in FIGS. 7 to 10 is that in the conventional manufacturing die 10, the upper die is the inner die and the outer die. It has two for molding,
Therefore, a means for moving the lower moving mold 11 between the two molds 12 and 13 is also required. The inner race 2 is first molded and then the outer race 3 is molded to manufacture the hub 1. It was However, in the hub manufacturing method of the present invention, it is possible to realize the production of the excellent hub 30 as described above by molding the outer ring body first and then molding the inner ring body, and in the die 20, the upper metal mold is used. Both the outer ring body 33 and the inner ring body 32 can be molded by one type of upper and lower molds 41 and 42 without providing two types of molds (fixed molds).

Next, a specific method for manufacturing the hub 30 will be described with reference to FIGS. 3 and 4. 3 and 4 are cross-sectional views of the mold 20 in each step for manufacturing the tape cassette hub 30 of the present invention. In both figures, the same components as those in FIGS. 7 to 10 are designated by the same reference numerals, and detailed description thereof will be omitted. In addition, in both figures, illustration of a part of the configuration such as the penetration pin and the protruding pin is omitted. 43 is a movable core, and by forming the movable core up and down, the molding spaces 25 and 27 of both the outer ring body 33 and the inner ring body 32 are formed.

First, in order to mold the outer ring body 33, the upper and lower molds 42 and 41 are overlapped with each other as shown in FIG. 3, and the movable core 43 constituting the lower (moving) mold 41 is moved upward (direction of arrow X). Let me die
Molten synthetic resin is injected and cooled in a space 25 formed by abutting against 42. Then, before the resin of the outer ring body 33 is completely solidified, the movable core 43 is moved downward (in the direction of the arrow Y) to a predetermined position as shown in FIG. 4, and the space 27 is formed by the molten synthetic resin for the inner ring body. Inject. In that case, if the resin for the inner ring body is injected after the resin of the outer ring body 33 is sufficiently solidified, the pressure penetration of the resin for the inner ring body into the outer ring body 33 does not occur as indicated by the arrow 35 in FIG. Therefore, in the method of the present invention, the cooling of the resin for the outer race is slowed down,
Further, the portion where the infiltration portion 34 is formed is made thick.

The increase in time due to slow cooling and solidification is
This is shorter than the time required to move the movable mold 11 between the upper molds 12 and 13 in the conventional method. It should be noted that instead of slowing the cooling and solidification, it is better to speed up the downward movement of the movable core 43. Specifically, it is preferable to move the movable core 43 and inject the resin for the inner ring body within 2 seconds after molding the outer ring body 33 (completion of resin filling). Further, since cooling and solidification occur first from the outer side in contact with the molds 41, 42, the infiltration part 34 generated by injecting the resin for the inner race is
It will always be possible to form in the central part where the solidification is slow, and both wheels 32,3
The shape is such that the fitting of 3 is performed sufficiently well. Although a part of the outer ring body 33 is formed to be thick, since the inner ring body molding resin is injected at a high pressure before the outer ring body 33 is completely cooled and solidified, the penetration portion 34 is formed. ,
As a result, the outer ring body 33 also plays a role of preventing sink marks from occurring. In this way, the tape cassette hub 30 according to the present invention is manufactured in a shorter time than the conventional manufacturing method. The molding resins may be of the same type or of different types, such as a combination of POM and ABS.
Resins that are difficult to adhere to each other can be integrally bonded.

[Effect]

The tape cassette hub and the manufacturing method thereof according to the present invention have the following excellent features.

It is possible to manufacture a hub that does not cause sink marks during molding and that can completely prevent positional deviation between the inner ring body and the outer ring body.

In the conventional method, two molds are required, and only one mold is required, which is economical, the manufacturing apparatus is simplified, and the time efficiency can be improved.

There is no need to make the joints between the inner and outer ring bodies rough, and there is no hindrance to the release of the molded product from the mold during molding, improving productivity.

[Brief description of drawings]

1 is a plan view of a tape cassette hub of the present invention, FIG.
1 is a cross-sectional view taken along the alternate long and short dash line AA in FIG. 1, FIGS. 3 and 4 are cross-sectional views of a mold in each step for manufacturing the tape cassette hub of the present invention, FIG. 5 and FIG. FIG. 6 is a sectional view of a hub manufactured by a conventional method, and FIGS.
The drawings are cross-sectional views in each step of a mold showing a conventional hub manufacturing method. 17 to 19 …… Sleeve, 20 …… Mold, 25,27 …… Resin molding space, 30 …… Hub, 32 …… Inner ring, 33 …… Outer ring,
34 …… Infiltration part, 41 …… Lower mold, 42 …… Upper mold, 43 …… Movable core.

Claims (2)

[Claims] 1. A hub for a tape cassette, which is manufactured by a two-color molding method and comprises an outer ring body and an inner ring body, wherein the molding resin for the inner ring body is injected before the molding resin for the outer ring body is cooled and solidified. As a result, at least a part of the outer peripheral portion of the inner ring body is formed with an intruded portion protruding into the outer ring body, and the inner ring body is fitted and fixed to the outer ring body by the intruded portion. Hub for tape cassettes. 2. In a hub for a tape cassette manufactured by a two-color molding method, before the primary side molded product is cooled and solidified,
Shafts of the primary side and secondary side molded articles are obtained by molding the secondary side molded article and injecting part of the secondary side molded article into the semi-molten primary side molded article by injection pressure to solidify. A method of manufacturing a hub for a tape cassette, which is characterized in that it is formed by a combined body of both molded products having no relative displacement in the direction.