JPH0510210B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for molding a tape reel integrally molded from synthetic resin, and more specifically, the present invention relates to a method for molding a tape reel integrally molded from a synthetic resin, and more specifically, a tape reel side plate is formed of a hole formed by a radial rib and an outer circumferential rib. The present invention relates to a method for molding open tape reel parts, particularly tape reel parts for video tape recorders.

[Conventional technology and its problems]

The tape reel used in home video tape recorders has a slightly different shape depending on the standard, but its basic structure is the same: a side plate that supports the tape on both sides, a tape core winding, a rotating shaft, and a power source that receives power from the video deck. It includes a transmission section. Such tape reels are usually made of synthetic resin, but tape reels for video tape recorders are required to have shape accuracy such as the flatness of the reel, the roundness of the tape core, and to prevent static electricity. Noh,
High performance in terms of durability, friction characteristics, etc. is required. In order to meet these requirements, the side plate, tape core, rotating shaft, and power transmission part have traditionally been integrally molded using polyacetal resin, which has a relatively good balance of various properties. A method has been adopted in which only the side plates are molded from styrene resin and the two are combined.

By the way, when molding such a tape reel component, that is, a component in which the side plate, tape winding core, etc. are integrally molded, in view of the required characteristics,
It is clear that certain restrictions exist on the thickness, shape, etc. of the side plates and tape core. On the other hand, from the standpoint of reducing the manufacturing cost of the tape reel and increasing its economic efficiency, it is required to reduce the thickness of the side plates and the like to reduce the weight of the molded product. therefore,
When designing tape reel components, it is an extremely important issue how to balance various required performances with economic efficiency.

[Means for solving problems]

In order to solve these problems, the inventors of the present invention have conducted various studies and have developed the present invention. In other words, the present invention provides a bearing section that pivotally supports a device rotating shaft, a tape core concentric with the bearing section, a plurality of radial ribs extending radially outward from an end of the tape core, and a plurality of radial ribs extending radially outward from an end of the tape core. When integrally molding a tape reel component made of a synthetic resin, the tape reel component is made of a synthetic resin and consists of a continuous outer circumferential rib that connects the outer ends of each rib and is concentric with the bearing part and has a constant thickness.
This is a tape reel molding method characterized by using a tape reel mold in which a parting line where a stationary mold and a movable mold come into contact does not exist on the surface that contacts the tape.

In such a tape reel molding method, burrs are likely to occur on the parting line where the cores of the stationary mold and the movable mold contact, and if these burrs occur on the surface that contacts the tape, there is a risk of damaging the tape. be. In the present invention, in order to prevent burrs from forming at least on the contact surface of the tape, the parting line of the mold is placed at a position away from surfaces such as ribs that come into contact with the tape, preferably on the back surface of the tape reel on the opposite side of the tape contact surface. Molding is performed using a mold that exists, or a mold that exists at any location within the thick region of the rib, preferably near the center.

According to the present invention, the tape reel component includes a bearing section (power transmission section) that pivotally supports the rotating shaft of a device such as a video deck, and a cylindrical tape core around which the tape is wound. The bearing part and the tape winding core are concentric, and the tape winding core is provided around the outer periphery of the bearing part and winds or unwinds the tape by rotation of the rotating shaft of the device.

A plurality of ribs extend radially outward from the end of the tape core. There are no particular limitations on the number or shape of the ribs, but generally there are about 3 to 15 ribs, preferably 6 to 9 ribs, each having a width of 3 to 6 mm. In addition, the ribs are not only linear, but also arcuate,
It can also take any other shape such as a curved shape. Furthermore, the width of the ribs does not have to be uniform from the starting point to the ending point. The type of these materials is appropriately selected depending on the windability of the tape, the surface runout of the reel, the strength, the beauty of the appearance, the ease of manufacture, etc.

The shape of the tape core is usually cylindrical, and a tab piece for fixing the end of the tape is attached. A radial rib continues from the outer periphery of the cylindrical body near the end of the tape core, that is, one end of the cylindrical body. The strip may be continuous to the radial ribs. With such a structure, the tape can be dust-proofed. Moreover, one or more of these strip-shaped bodies may be provided at any arbitrary position between the winding core end and the outer circumferential rib depending on the purpose of use. Each end of the radial rib extending from the end of the tape core is connected by an outer peripheral rib. This outer circumferential rib is concentric with the tape core and is raised to a certain thickness in order to reduce surface runout and increase rigidity. That is, in the present invention, the side plate, which is a tape reel component, is formed by radial ribs and outer circumferential ribs, or further by a band-shaped body. The above-mentioned bearing portion, tape core, radial ribs, and outer circumferential ribs are integrally molded from thermoplastic resin. The thermoplastic resin used in the present invention includes polyacetal, polyester such as polybutylene terephthalate, polyethylene terephthalate, ABS,
Although polyamide etc. can be used, other thermoplastic resins can also be used depending on the purpose of use. Polyacetal is particularly suitable because of its high dimensional accuracy, stability, durability, and excellent friction properties. To give an example of how to assemble a video tape reel, a tape reel may be produced by combining the styrene resin molded part that becomes the other side plate with the tape reel portion of the present invention.

In this way, the present invention uses radial ribs and outer circumferential ribs to form the tape reel component, which was conventionally composed of a disk-shaped side plate with a uniform thickness.
The weight of the tape reel can be significantly reduced compared to conventional tape reels. That is, the weight of the conventional part is about 15g, whereas the weight of the part of the present invention is only 10g.

Even though the weight is reduced in this way, the strength of the parts,
Rigidity is still maintained by the radial ribs, thus achieving a balance between performance and economy, as well as reducing the load on the rotating shaft of the equipment.
It is extremely useful as it extends the life of the equipment.

Another advantage of the present invention is that the molding cycle can be shortened by increasing the number of cavities in the same molding machine. In other words, the number of cavities is determined by the cavity pressure during molding and the mold clamping force of the molding machine, and the size of the mold is also a factor in determining the number of cavities. In this case, the projected area of the molded product will be smaller than in the past, and it can be expected that the number of cavities will increase.

Accordingly, in the present invention, when molding the tape reel of the perforated side plate consisting of the radial ribs and the outer circumferential ribs as described above, the movable mold and the fixed mold are used as molding molds. By using a structure in which the contacting parting line does not exist on the surface in contact with the tape, preferably on the back side of the tape reel rib on the opposite side from the core of the tape reel, the parting line that is in contact with the tape reel can be particularly There are no burrs on the surface of the ribs that come into contact with the tape, which has the effect of completely preventing accidents that would cause damage to the tape due to burrs.

This will be explained in more detail below with reference to Examples.

In the embodiment of the present invention shown in FIG. 1, a flat disk-shaped tape reel component 1 has a bearing portion 2 at its center. As shown in FIG. 2, the bearing part 2 has a toothed part 3 on its inner surface that engages with the rotating shaft of the device, and is also provided with a rotating shaft 4 and a protrusion 5 on its upper part. This protrusion 5 is inserted into a hole provided in the other side plate (not shown) and then melted to assemble the tape reel. A tape winding core 7 is provided on the outer periphery of the bearing portion 2 with a reinforcing plate 6 interposed therebetween. Its thickness is approximately 1 mm or more so that it will not be deformed by the force of wrapping the tape. Further, it is preferable that the surface of the winding core 7 is smooth. The end of the winding core 7 is formed as a disc-shaped band 8, from which nine radial ribs 9 are formed.
extends radially. Its width is approximately 4 mm, and its thickness gradually decreases as it approaches the outer periphery. For example, a =
1.5~b=1.2mm. The ends of the radial ribs 9 are each connected by an outer circumferential rib 10. Note that the outer circumferential surface of the outer circumferential rib 10 is provided with retaining teeth 11 for preventing reverse rotation of the reel, and the outer circumferential rib 10
The lower surface of the radial rib 9 is thicker than the radial rib 9 in order to reduce surface runout and increase rigidity (for example, approximately c=
1.7mm)

In the embodiment of the invention shown in FIG. 3, the strip 8 formed at the end of the tape core 7 has a larger diameter than in the embodiment of FIG. An example of the diameter of the belt-shaped body of the present invention is the diameter of a conventional product.
It is 45mm compared to 30mm. Such a shape is more effective in dustproofing the tape wound on the tape reel.

FIG. 4 shows the tape fixing claw piece 12 attached to FIG. 1. Further, FIG. 5 shows an embodiment of a videotape reel according to the present invention, in which a semicircular toe piece, which is larger in shape than the toe piece in FIG. 4, is attached.

In FIG. 6, each radial rib 9 is configured to form a circular hole 13 between adjacent radial ribs. The shape of this hole is appropriately determined depending on the purpose of use, but is not particularly limited. 6th
When the tape reel has a circular hole as shown in the figure, the strength of the tape reel can be maintained well.

In particular, in the method for forming tape reel parts according to the present invention, in order to prevent burrs from appearing on the surface in contact with the tape and damaging the tape, the tape reel parts are in contact with the tape as shown in FIGS. 7a and 7b. Molding is performed using a mold in which a parting line 17 of a stationary mold 15 and a movable mold 16 is provided on the back surface 14 on the opposite side of the surface.

Alternatively, as shown in FIG. 7c, molding may be performed using a mold in which the parting line 17 is located within the thick region of the radial rib 9, particularly near the center of the wall thickness.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of the tape reel component according to the present invention, FIG. 2 is a sectional view taken along line A-A' in FIG. 1, and FIGS. FIG. 4 is a plan view showing another embodiment of the tape reel component according to the invention, FIG. 4 is a plan view showing an embodiment in which a tape toe piece is attached to FIG. 1, and FIGS. 7 a to c are tape reel components according to the invention. FIG. 2 is an explanatory diagram showing the positional relationship between the molded product and the parting line of the mold used in the molding method of FIG. 1...Tape reel parts, 2...Bearing section, 3...
...Tooth portion, 4...Rotating shaft, 5...Protrusion, 6...Reinforcement plate, 7...Tape winding core, 8...Strip-like body, 9...Radial rib, 10...Peripheral rib, 11...Stop teeth,
12... Towel piece, 13... Hole, 14... Back side of tape reel, 15... Fixed side mold, 16... Moving side mold, 17... Parting line.

Claims (1)

[Scope of Claims] 1. A bearing portion for pivotally supporting a device rotation shaft, a tape core concentric with the bearing portion, a plurality of radial ribs extending radially outward from an end of the tape core, and the plurality of radial ribs extending radially outward from an end of the tape core. When integrally molding a tape reel component made of a synthetic resin, the tape reel component is formed by connecting the outer ends of each of the radial ribs, and is concentric with the bearing part and has a continuous outer circumferential rib raised to a constant thickness. A tape reel molding method characterized by using a tape reel mold in which a parting line where a stationary mold and a movable mold come into contact does not exist on the surface that contacts the tape. 2. The tape reel molding method according to claim 1, which uses a tape reel mold in which the parting line is on the back surface of the tape reel opposite to the surface in contact with the tape.