JPH0216022A - Ferrule injection molding die - Google Patents

Abstract

PURPOSE:To prevent the thickening of the front end section of a ferrule by forming a bush of a heat-insulating material, mounting the outer circumference of the bush to a template in an airtight manner and installing a bend between the outer circumference in 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 shaping the side fronter than the flange section 11 of a ferrule 1. A sprue bush 51 is set up to the template 5, and a sprue 52 is formed. A bush 6 is shaped so that the cavity 55 formed by the template 5 is interrupted substantially by a perpendicular, and the bush 6 is composed of an external body 62 and an internal body 64 shaped by a heat-insulating material, and formed in double structure. The external body 62 of the bush 6 is fitted to the template 5 in an airtight manner through a heat-resistant O ring 61. A clearance 63 shaped between the external body 62 and the internal body 64 bears the function of a bend. The quenching of the front end section of the ferrule 1 is inhibited by forming the bush 6 of the heat-insulating material, and the cooling of a molded form is balanced excellently, thus suppressing thickening at the front end section of the ferrule 1.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a ferrule injection mold in which a bushing is formed of a heat insulating material to suppress thickening at 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 Q/< section 15 is a guide when attaching the optical fiber.

Such a ferrule 1 is used to form an FC connector, and there is also a ferrule 1 having a form without the rear part 13 of the flange portion 11 (FIG. 4). In addition, 12 is the flange part 11
This is a groove 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 the mold, as shown in Fig. 3, the ferrule 1
A center pin 2 having an outer shape corresponding to the internal cavity is provided in the cavity, and a bush 4 is provided on the mold plate 3 forming the cavity, so that the tip of the narrow diameter portion 21 of the center pin 2 is inserted when the mold is clamped. There were known things that made it look like this.

However, when the ferrule 1 is injection molded using a conventional mold, there is a problem that the tip end 17 of the resulting ferrule 1 becomes thicker. In optical connectors that require control on the micron order for optical fiber axis alignment, the thickening of the tip of the ferrule 1 hinders reproducibility in repeated attachment and detachment of the optical connector. Even if the ferrule has a chamfered tip as shown in FIG. 4, the rear portion 17 becomes thicker as shown in FIG. 5, which again causes a problem of inhibiting reproducibility.

There is a proposal to make the tip of the ferrule convex spherical to avoid the thickening problem, but making the tip of the ferrule convex reduces the contact area, which increases the contact pressure and makes the optical fiber more likely to be damaged. Undesirable. There are also other drawbacks, such as the contact surface being prone to slipping. In addition, it is difficult to manufacture a mold having a cavity for injection molding such a ferrule. It is possible to create a mold by electroforming, but it has the drawback of poor durability due to material constraints.

Means for Solving the Problems The present invention overcomes the above-mentioned problems with ferrules by forming the bushing with a heat insulating material.

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 present invention provides a mold for injection molding a ferrule, into which the tip of the narrow diameter portion of the center pin is inserted, and the bush is made of a heat insulating material.

Actions and Effects In FIG. 6, 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 plates 5, 8
The outer shape of the ferrule 1 is formed based on the outer shape of the cavity formed by the bushing 6 and the bushing 6. The bushing 6 is made of a heat insulating material, which suppresses rapid cooling of the tip of the molded product.

As a result, cooling of the molded product is well balanced, thickening at the tip of the molded product is suppressed, and ferrules with excellent dimensional accuracy can be mass-produced by injection molding. Furthermore, an optical connector equipped with such a ferrule has excellent attachment/detachability and reproducibility.

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, 49811 IIl, the total length is 14-, the outer diameter of the flange portion 11 is 4, 2 wm, and the length is 3 wa
The length of the rear part 13 of the flange part is 3 m, the diameter of the large hole part 14 in the internal cavity is 11111%, and the length of the tapered part 15 is 1
m1 diameter of small diameter part 16 0.126ma+, length 1.5+w
A ferrule 1 having the specifications shown in FIGS. 1 and 2 with a as a standard dimension is molded. Note that the mold is vertically symmetrical via the center pin 7 in the figure.

The template 5 is the fixed side, and the flange 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 the cavity 55 formed by the template 5 in a vertical plane. Also, Bush 6
consists of an outer body 62 and an inner body 64 made of a heat insulating material, and has a double structure.

As shown in FIG. 7, the outer body 62 of the bushing 6 is airtightly attached to the template 5 via a heat-resistant O-ring 61. The vent function is performed by a gap 63 provided between the outer body 62 and the inner body 64. Note that the inner body 64 has an insertion hole 65 for the narrow diameter portion 71 of the center pin 7 at its center.

The template 8 is a movable side, and has a cavity portion 81 for forming the rear i13 of the flange portion 11 in the ferrule 1.
have.

The center pin 7 includes a small 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. When the mold is clamped, the tip of the narrow diameter portion 71 of the center pin 7 is inserted into the insertion hole 65 of the bushing 6.

An ejector pin 91 is attached to the plate 9 of the receiver, and the molded ferrule is ejected when the mold is opened. The ejector bin 91 is made of a ring body corresponding to the thick part of the ferrule 1.

Incidentally, 100 shots of a ferrule made of polyphenylene sulfide were injection molded using the above mold, and the variation in the outer diameter at the tip was examined, and the variation was within 19 m from the standard dimension. Moreover, no cracks were generated on the outer periphery of the tip.

The mold of the present invention is for injection molding a ferrule for an optical connector, and is not particularly limited except that the bushing is formed of a heat insulating material. Therefore, the positions of the sprue and gate, the shape and position of the ejector bin, etc. may be determined as appropriate. In addition, as illustrated in FIG. 4, the shape and dimensions of the ferrule may be determined as necessary, such as by molding the ferrule into a ferrule without the rear part 13 of the flange portion 11 or a ferrule with a chamfered tip. You may do so.

In the above-mentioned embodiment, the bushing has a double structure and a vent is provided in its thick part, but the bushing may be made as a single piece and a gap is provided between the outer periphery and the template to form a vent. Moreover, you may combine them.

As in the above-mentioned embodiment, a method in which a vent is provided in the thick part of the bushing and the outer periphery of the bushing is airtightly attached to the template prevents the formation of flakes on the outer periphery of the tip of the ferrule to be molded. Inhibition III L is advantageous for manufacturing ferrules with even better dimensional accuracy. Therefore, it is advantageous for manufacturing optical connectors that are excellent in attachment/detachability and reproducibility.

The heat insulating material for forming the bushing may be determined as appropriate. Any material may be used as long as it can slow down the cooling rate of the part of the molded product, which corresponds to the tip of the ferrule, and is particularly susceptible to rapid cooling. Among these, it is preferable to make the cooling rate as equal as possible to the cooling rate in other parts of the molded article.

The heat insulating material may be formed of a heat insulating material with poor thermal conductivity, or may exhibit heat insulating properties based on its structure, such as having a porous structure. Of course, a heat insulating structure may be formed using a heat insulating material. If the material exhibits heat insulating properties based on its structure, it is desirable to make at least the surface in contact with the molding resin smooth. Common materials used to form the bush include ultra-heat resistant plastics such as aromatic polyamide, polyimide, polyphenylene sulfide, polybenzimidazole, and ceramics. When a ceramic sintered body is formed, it can normally be used as is, but if the surface has large irregularities due to holes etc., it is preferable to smoothen the surface that will come into contact with the molding resin.

The molding resin 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 part: Large hole part 15: Tapered part 16: Small hole part 5°8: Template 55.81. Cavity: Bush 62: Outer body 64: Inner body 65: Insertion hole 7: Center pin 71: Small diameter part 72: Tapered part 73: Large diameter part: Receptacle is plate

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. 1. A mold for injection molding a ferrule, into which a tip end of a narrow diameter portion is inserted, and the bushing is made of a heat insulating material.