JPH0216021A - Ferrule injection molding die - Google Patents

Abstract

PURPOSE:To prevent the generation of a burr to the front end of a ferrule by mounting the outer circumference of a bush to a template in an airtight manner and installing a bend between the outer circumference of the bush and the inserting hole of a center pin. CONSTITUTION:A template 5 is positioned on the fixing side, and has a cavity section 55 for forming the side fronter than the flange section 11 of a ferrule 1. A sprue bush 51 is mounted to the template 5, and a sprue 52 is shaped. The bush 6 is formed so that the cavity 55 shaped by the template 5 is interrupted substantially by a perpendicular, and set up to the template 5 in an airtight manner. That is, the bush 6 is formed in double structure by an external body 62 and an internal body 64, the external body 62 is fitted through a heat- resistant O ring 61, and the bush is shaped in airtight structure. Consequently, a section between the template 5 and the bush 6 is sealed and is not operated as a bend, thus preventing the generation of a burr in the outer circumferential section of the front end of the ferrule 1 acquired. A clearance 63 shaped between the external body 62 and the internal body 64 bears the function of the bend.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a mold for injection molding a ferrule, which prevents the formation of cracks due to vents on the outer circumference of the tip of a ferrule for an optical connector.

BACKGROUND OF THE INVENTION As illustrated in FIGS. 1 and 2, a ferrule used for forming an optical connector that is essential for connecting optical fibers in optical communications, etc. has a tapered part with a small hole 16 and a wide hole 14 inside. It is known that the cylinder body 1 has a hollow structure that communicates through a tube 15 and has a flange portion 11 on the outer periphery. The flange portion 15 functions as a guide for the attached optical fiber. The ferrule 1 described above is used for forming an FC connector, and there is also a type without the rear part 13 of the flange portion 11 (FIG. 4). Note that 12 is a groove provided in the flange portion 11 to prevent rotation.

As optical communications begin to spread into homes, large-scale demand for such ferrules is predicted, and there is an urgent need to provide mass production technology.
This has become an important issue.

BACKGROUND ART Conventionally, injection molding methods have been proposed to meet the demands for mass production technology described above.

As shown in FIG. 3, the mold is provided with a center pin 7 having an outer shape corresponding to the internal cavity of the ferrule 1 described above in the cavity, and a bush 4 provided on the template 2 in which the cavity is formed. When clamping the mold, the tip of the narrow diameter portion 71 of the center pin 7 is inserted,
In addition, it is known that a gap 3 is provided between the outer periphery of the bushing 4 and the template 2, and this gap is used as a vent.

However, when the ferrule 1 is injection molded using a conventional mold, resin enters the vent 3 between the outer periphery of the bushing 4 and the template 2, and there is a problem in that the outer periphery 17 of the tip of the ferrule 1 is formed. Ta.

In optical connectors that require control on the order of microns for optical fiber axis alignment, there is large variation in the periphery 17 of the ferrule tip, and this, combined with shrinkage of the molded product, becomes a fatal defect. Furthermore, reproducibility is inhibited when repeatedly attaching and detaching the optical connector.

Even if the ferrule has a chamfered tip as shown in Fig. 4, a crack will still occur on the outer periphery 17 as shown in Fig. 5.
cause the same problem.

In order to avoid the above-mentioned paring problem, there has been proposed a mold in which a center pin insertion hole is directly formed in the mold plate without using the bushing method. However, it is difficult to manufacture the mold with high dimensional accuracy, and the molded ferrule has the disadvantage of poor dimensional accuracy. It is possible to create a mold by electroforming, but
The drawback is that it lacks durability due to material constraints.

Means for Solving the Problems The present invention overcomes the above problems with ferrules by attaching the outer periphery of the bushing to the template in an airtight manner and providing a vent between the outer periphery of the bushing and the center pin insertion hole. This is what I did.

That is, the present invention is for injection molding a ferrule for an optical connector, which is composed of a cylindrical body having a flange portion, and has a structure in which a cavity inside the cylindrical body has a small hole portion and a large hole portion communicating with each other via a tapered portion. A center pin having an outer shape corresponding to the internal cavity of the ferrule is installed in the cavity of the mold, and a button is provided on the mold plate forming the cavity, so that when the mold is clamped, The tip of the narrow diameter portion of the center pin is inserted, and the outer periphery of the bushing is airtightly attached to the template, and the outer periphery of the bushing and the narrow diameter portion of the center pin are inserted. The present invention provides a ferrule injection mold characterized by having a vent between the insertion hole and the insertion hole.

Actions and Effects In FIGS. 6 and 7, by injecting molding resin into the cavity, the internal cavity of the ferrule 1 is formed based on the center pin 7 provided in the cavity, and the mold plate 5
．． The outer shape of the ferrule 1 is formed based on the outer shape of the cavity formed by the bushing 8 and the bushing 6.

The outer periphery of the bush 6 is airtightly attached to the template 5, so that the space between them does not function as a vent, and no flaking occurs on the outer periphery of the tip of the molded ferrule 1.

The function of the vent is between the outer periphery of the bushing 6 and the insertion hole 65 of the center pin narrow diameter part 71, that is, between the bushing 6 and the insertion hole 65 of the center pin narrow diameter part 71.
The gap 63 provided in the thick part of the wall plays this role. Therefore, this position corresponds to the thick portion at the tip of the obtained ferrule 1. This part does not harden as quickly as the outer periphery of the molded article (corresponding to the outer periphery of the bush), so it maintains a fluid state well, and only a small amount of flaking occurs. Furthermore, even if we assume that a gap occurs, the center side of the molded product corresponding to the thick part at the tip of the ferrule will have a large sink mark or dent due to shrinkage. The impact is reduced.

As a result of the above, it is possible to obtain a ferrule that is mass-produced by injection molding and has excellent dimensional accuracy, ease of attaching and detaching the optical connector, and reproducibility of attaching and detaching the optical connector. The sink marks and dents mentioned above are problems within the tolerance range of the dimensions of the molded product, and are based on a microscopic viewpoint of micron oak or smaller.

Embodiment FIG. 6 illustrates a mold for injection molding a ferrule according to the present invention. 5 and 8 are templates, 6 is a bushing, 7 is a center pin, 9
The uke is a board. With this mold, the outer diameter of the cylindrical body 1 is 2,498 m, the total length is 14-, the outer diameter of the flange part 11 is 4,2 wra, and the length is 3III111.
The length 3-1 of the rear part 13 of the flange part is 1 mm in diameter of the large hole 14 in the internal cavity, the length of the tapered part 15 is 1 mm, and the diameter of the small diameter part 16 is 0. Ferrule 1 with the specifications shown in Figures 1 and 2, with standard dimensions of f26+n+n and length 1.5m.
is formed. In addition, the mold has center pin 7 in the diagram.
It is symmetrical through the top and bottom.

The template 5 is the fixed side, and the 7 run part 11 of the ferrule 1
It has a cavity portion 55 for forming a more anterior side. A sprue bush 51 is attached to the template 5 and a sprue 52 is provided. Molding resin injected from a nozzle (not shown) is supplied into the cavity 55.81 by sequentially valves the sprue 52, runner 53, and gate 54.

The bushing 6 is formed so as to substantially block a cavity 55 formed by the template 5 on a vertical plane, and is attached to the template 5 in an airtight manner. That is, as shown in FIG. 7, the bushing 6 is formed into a double structure by an outer body 62 and an inner body 64, and the outer body 62 is attached via a heat-resistant O-ring 61 to form an airtight structure. As a result, the space between the template 5 and the bush 6 is sealed, so that the space between them does not function as a vent, and the formation of cracks on the outer periphery of the tip of the resulting ferrule 1 is prevented. The vent function is performed by a gap 63 provided between the outer body 62 and the inner body 64. The inner body 64 has an insertion hole 65 at its center for receiving the tip of the narrow diameter portion 71 of the center pin 7 when the mold is clamped.

The template 8 is on the movable side and has a cavity portion 81 for forming the rear portion 13 of the flange portion 11 in the ferrule 1.
have.

The center pin 7 includes a narrow diameter portion 71, a tapered portion 72, and a large diameter portion 73, and has a shape corresponding to the internal cavity of the ferrule 1. The center pin 7 is fixed to the plate 9 so that its axial center coincides with the center of the cavity 55.81 described above.

An ejector pin 91 is attached to the plate 9 of the receiver, so that the molded ferrule 1 is ejected when the mold is opened. Ejector bin 91 is ferrule 1
Consists of a ring body that corresponds to the thick part of the

By the way, 100 shots of ferrules made of polyphenylene sulfide were injection molded using the above-mentioned mold, and the shape and variation of the outer periphery of the tip were investigated. There was no problem with the outer periphery of the tip, and the ferrule was 1lffi compared to the standard outer diameter. The degree of variation was within

In the present invention, a vent is provided in the thick part of the bushing,
There are no particular limitations on the mold, except that the outer periphery of the bushing is airtightly attached to a mold plate and the ferrule for an optical connector is injection molded.

Therefore, the positions of the sprue and gate, the shape and position of the ejector bin, etc. may be determined as appropriate. Also,
As illustrated in FIG. 4, the shape and dimensions of the ferrule 1 may be determined as necessary, such as forming a ferrule without the rear part 13 of the flange portion 11 or forming a ferrule with a tapered tip. You may do so.

Although the bush has a double structure with a vent in the above embodiment, the present invention is not limited to this, and it is sufficient if the bush has a vent in its thick part. The material for forming the bushing may be metal or a heat insulating material such as ceramic. A bushing made of a heat insulating material or a heat insulating structure such as porous material is preferable in terms of suppressing rapid cooling of the tip of the molded product, improving the heat radiation balance of the entire molded product, and improving the dimensional accuracy of the resulting ferrule.

On the other hand, the resin for forming the ferrule is preferably one with excellent moldability and dimensional stability, and polyphenylene sulfide, polyether sulfone, etc. are preferably used, but the resin is not limited thereto and may be determined as appropriate.

[Brief explanation of the drawing]

Fig. 1 is a front view of a structural example of the ferrule, Fig. 2 is a side sectional view thereof, Fig. 3 is an explanatory sectional view of a conventional example, Fig. 4 is a side sectional view of another structural example of the ferrule, and Fig. 5. 6 is an explanatory sectional view of another conventional example, FIG. 6 is a sectional view of an embodiment, and FIG. 7 is an enlarged sectional view of the bushing. 1: Ferrule (cylindrical body) 11: Flange portion 14: Large hole portion 15: Tapered portion 16: Small hole portion 5.8: Template 55.81: Cavity 6: Push 61: Heat resistant ring 62: Outer body 63: Vent 64: Inner body 65: Insertion hole 7: Center pin 71: Small diameter portion 72: Tapered portion 73: Large diameter portion 9: Receiving plate Figure 10 Figure 2 Patent applicant Mitsubishi Cable Industries, Ltd.

Claims (1)

[Claims] 1. A mold for injection molding a ferrule for an optical connector, which is composed of a cylindrical body having a flange part, and has a structure in which a cavity inside the cylindrical body has a small hole part and a large hole part connected through a tapered part. A center pin having an outer shape corresponding to the inner cavity of the ferrule is installed in the cavity of the mold, and a bush is provided on the mold plate forming the cavity, so that the center pin has a bush when the mold is clamped. The tip of the narrow diameter portion is inserted, and the outer periphery of the bush is airtightly attached to the template, and the outer periphery of the bush and the insertion hole of the narrow diameter portion of the center pin are connected. A mold for ferrule injection molding, characterized by having a vent in between.