JPS63307919A - Molding method for tape reel - Google Patents

Abstract

PURPOSE:To prevent flashes from being generated by using a tape reel mold without a parting line formed on the contact face by contact of mold on the fixed side with a mold on the movable side. CONSTITUTION:In molding a tape reel 1 of a perforated side plate consisting of a radial rib 9 and an outer peripheral rib 10, a molding die should be of a structure that a parting line 17 is not formed by contact of a mold 16 on the movable side with a mold 15 on the fixed side on the face to be in contact with the tape, or more preferably, should be of a structure that the parting line is formed on a tape reel rib rear side 14 on the opposite side to a core tube of the tape reel. By said arrangement, flashes are not generated particularly on the rib face in contact with the tape of the perforated section, and trouble such as breakage of the tape with the flashes, can be completely prevented.

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]

Tape reels used in home video tape recorders have slightly different shapes depending on the standard, but the basic structure is the same: a side plate that supports the tape on both sides, two rotating shafts for the tape winding core, and a power transmission section that receives power from the video deck. Contains. 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. High performance is required in terms of performance, durability, friction characteristics, etc. In order to meet these requirements, the side plate, tape winding core 9 rotating shaft, and power transmission part have traditionally been integrally molded using polyacecool 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 core, etc. are integrally molded, there are certain restrictions on the thickness, shape, etc. of the side plate and tape core due to the required properties. It is clear that there is.

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 and reel components, it is an extremely important issue how to strike a balance between various required performances and economic efficiency.

[Means for solving problems]

Therefore, the present inventors conducted various studies to solve such problems, and as a result, they obtained the present invention.

That is, the present invention provides a bearing for supporting a rotating shaft of a device;
The bearing connects a tape core concentric with the part, a plurality of radial ribs extending radially outward from an end of the tape core, and an outer end of each of the plurality of radial ribs. When integrally molding a tape reel component made of synthetic resin, which consists of concentric and continuous outer peripheral ribs raised to a constant thickness, the parting line where the stationary mold and the movable mold come into contact is the surface where the tape contacts. This is a tape and reel molding method characterized by using a tape and reel mold that does not exist in the past.

In such a tape reel molding method, burrs are likely to occur at the parting line where the cores of the stationary mold and the movable mold contact, and if these burrs occur on the surface that comes into contact with the tape, there is a risk of damaging the tape. be. In the present invention,
In order to prevent Paris from occurring at least on the contact surface of the tape, the parting line of the mold should be placed at a position away from surfaces such as ribs that come into contact with the tape, preferably on the back of the tape reel on the opposite side of the tape contact surface. Molding is carried out using a mold or a mold located 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 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 5 mm. Further, the ribs are not limited to linear shapes, but can also take any shape such as arcuate shapes or other curved shapes. 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 aesthetic 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. If you have a structure like this,
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.

The ends of each of the radial ribs extending from the end of the tape core are connected by an outer peripheral rib. This outer peripheral 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 (eg, polybutylene terephthalate, polyethylene terephthalate), and 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 assembling a video tape reel, a tape reel may be manufactured 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 tape reel component of the present invention, which was conventionally composed of a disk-shaped side plate of uniform thickness, is formed with radial ribs and an outer circumferential plate, so the weight of the tape reel can be significantly reduced compared to the conventional one. can be reduced to 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 and rigidity of the part is still maintained by the radial ribs, so it is possible to balance performance and economy, and it is also possible to reduce the load on the equipment rotation axis. It is extremely useful as it extends the life of the equipment.

Another advantage of the present invention is that the number of cavities can be increased in the same molding machine to shorten the molding cycle. 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, but when a tape reel component is configured as in the present invention, The projected area of the molded product will be smaller than that of conventional moldings, and this can be expected to increase the number of cavities.

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, a parting mold in which the movable mold and the fixed mold are in contact is used as a molding mold. By using a structure in which the 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 line is particularly in contact with the tape in the perforated area. There is no occurrence of flash on the surface of the ribs, and therefore, there is an effect of completely preventing accidents that would cause damage to the tape due to flash.

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 core 7 is provided on the outer periphery of the bearing portion 2 with a reinforcing plate 6 interposed therebetween. Its thickness is about 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 strip 8, from which nine radial ribs 9 extend radially. Its width is about 4mm
, the thickness 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 peripheral plate 10. Note that the outer peripheral surface of the outer peripheral rib 10 is provided with retaining teeth 1 for preventing reverse rotation of the reel.
1 is provided, and the lower surface of the outer peripheral rib 10 is provided with radial ribs 9 in order to reduce surface runout and increase rigidity.
(for example, about C=1.7 mm).

゛In the embodiment of the present invention shown in FIG.
The strip 8 formed at the end has a larger diameter than in the embodiment of FIG. An example of the diameter of the strip of the present invention is 45 mm, compared to the diameter of the conventional product, which is 3Q mm.
It is. 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. When the tape reel has a circular hole as shown in FIG. 6, the strength of the tape reel can be maintained well.

In particular, in the method of forming the tape reel component according to the present invention, in order to prevent the appearance of flakes on the surface in contact with the tape and damage the tape, the tape reel component is molded as shown in FIGS. 7(a) and 7(b). Fixed side mold 15 is placed on the back side 14 opposite to the side in contact with the tape.
The molding is performed using a mold having a parting line 17 of a movable mold 16.

Alternatively, as shown in FIG. 7(C), a parting line may be placed within the thick area of the radial rib 9, especially near the center of the wall thickness.
It may be molded using a mold having No. 7.

[Brief explanation of drawings]

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 AA' 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; FIGS.
C) is an explanatory diagram showing the positional relationship between the molded product and the parting line of the mold used in the method for molding the tape reel component according to the present invention. 1... Tape reel part 2... Bearing part 3... Teeth part 4... Rotating shaft 5... Protrusion 6... Reinforcement plate 7... Tape winding core end... Band-shaped body 9... Radial rib 10... Outer rib 11... Stop tooth 12... Toe piece 13... Hole portion 14... Tape reel back surface 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 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 the radial ribs and is concentric with the bearing part and has a constant thickness. A tape reel molding method characterized in that a tape reel mold is used in which a parting line where the mold and the moving side mold 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.