JPH02253207A - Production of ferrule for optical fiber connector - Google Patents

Abstract

PURPOSE:To enhance mass productivity and to increase the connecting stability of a coated optical fiber to a ferrule by forming a capillary from zirconia ceramics as a stock by injection molding and sintering means. CONSTITUTION:The capillary raw material 4' of a prescribed length which is bored with a prepd. hole 1a at the center, is subjected to chamfering 2 on the front surface and is formed with a tapered hole 3 at the center of the rear surface is produced from the zirconia ceramics as the stock by the injection molding and sintering means. After the prepd. hole 1a of the capillary raw material 4' is finished by hole polishing to a microhole 1 for insertion of the optical fiber 5a and is centered by outside diametral polishing and finishing. A sleeve 6 made of a stainless steel of a truly cylindrical shape subjected to the polishing for centering is produced in the same manner and the rear end side of the capillary 4 is press-fitted and fixed to the fitting hole 7 at the front end thereof in such a manner that the respective axial lines align to each other. The assembly work of the ferrule F is thus completed.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a method of manufacturing a ferrule for an optical fiber connector used for detachably connecting optical fibers.

B. Conventional technology Optical fibers have cores made of materials such as quartz glass with an extremely small diameter, so extremely sophisticated connection technology is required to accurately align and connect the axes of the optical fibers. Met.

Conventionally, in order to align and connect optical fibers, the center of the optical fiber core is aligned with the center of the cylindrical plug based on the outer diameter of the cylindrical plug, and then the center of the optical fiber core is aligned within the cylindrical plug. Optical fiber connectors that have a ferrule with a perfectly circular outer periphery inserted as a core are widely used.

Conventionally, the ferrule used in the optical fiber connector is manufactured through the steps shown in FIG.

First, a conventional capillary manufacturing process will be explained.

A long cylindrical capillary raw material 14' is made from alumina ceramics by extrusion molding and sintering. This capillary raw material 14' has a diameter of 0.1 mm to 0.0 mm at its center.
Drill a pilot hole 11 of about 11 mm. Of course, the outer diameter and pilot hole dimensions of the capillary raw material 14' are made slightly larger in preparation for later polishing. Then, it is cut to a predetermined length.

Next, after polishing the pilot hole 11 and polishing the outer diameter, the taper hole 13 is placed at the rear end of the capillary raw material 14''.
Open. This tapered hole 13 is for facilitating the insertion of an optical fiber, and its cutting angle is 90 degrees and the diameter of the rear surface is 0.8 mm in the finished dimensions. Note that drilling of this tapered hole is performed using a drill.

Finally, the tip of the capillary raw material 14' is chamfered 12. This chamfering 12 serves to facilitate insertion into an adapter that connects optical fiber connectors, and the finished dimensions are such that the notch angle is 30 degrees and the width is 0.5 to 0.6 mm.

In this way, from the capillary raw material 14' to the capillary 1
4 is finally completed.

On the other hand, as shown in FIG. 8, the cylindrical sleeve 16 into which the capillary 14 is press-fitted is made of stainless steel, and has a accommodating portion 17 for the capillary 14 at the tip, a collar 18 at the center or rear end, and a light beam at the rear end. Each is provided with a tapered hole 20 to facilitate insertion of the fiber wire. Of course, both the outer diameter and inner diameter of the sleeve 16 are centered so that the center of the sleeve 16 and the optical fiber axis are precisely aligned.

Then, the capillary 14 is placed in the tip accommodating portion 17 of the sleeve 16 and fixed with adhesive.

Conventional ferrule F' is assembled as described above.

Problems to be Solved by the Invention Since the conventional ferrule F' for an optical fiber connector is manufactured as described above, it has the following drawbacks.

b) In the conventional ferrule F' for connectors, the capillary 14 is made by extrusion molding using alumina ceramics, which is a particularly hard material among ceramics.
3 and chamfering 12, etc., the work is extremely difficult and time consuming, and therefore poses a problem in mass production.

As mentioned above, since hard alumina ceramics are used, when forming the tapered hole 13 with a drill, a drill with an acute cutting edge tends to break the cutting edge (therefore, only drills with an obtuse cutting edge could be used.

Therefore, as mentioned above, the tapered hole 13 of the conventional capillary 14 has a cutting angle of 90 degrees and a rear diameter (aperture) of 0.8 m.
m, but the outer diameter of the corresponding optical fiber (nylon jacket) is usually around 0.9 mm, which has the disadvantage that it is difficult to insert the optical fiber smoothly. .

Especially when drilling holes using a drill, taper hole 13
The processing of the intersection between the optical fiber insertion hole (prepared hole 11) and the optical fiber insertion hole (prepared hole 11) was not successful, and a so-called burr-like appearance occurred in that area.
There was a risk of damaging the optical fiber.

To avoid this, conventional techniques have been used, such as measuring the distance until the tip of the optical fiber hits the intersection, marking it on the outside of the optical fiber (nylon jacket), and then inserting it. However, this caused a significant decrease in work efficiency.

c) In the conventional ferrule F', the entire small capillary 14 is completely inserted into the tip of the cylindrical sleeve 16 and fixed with adhesive, so the assembly of the ferrule F' is not only complicated and time-consuming. , it was quite difficult to align the centers accurately.

2. Means for solving the above-mentioned problems The present invention provides a method for manufacturing a ferrule for an optical fiber connector that eliminates the above-mentioned drawbacks. A ceramic cylindrical capillary 4 having a chamfer 2 and a tapered hole 3 concentrically communicating with the microhole 1 at the center of the rear, and a metal to which the rear side of the capillary 4 is press-fitted. Alternatively, in a method of manufacturing a ferrule for an optical fiber connector comprising a cylindrical sleeve 6 made of plastic, the capillary 4 is molded from zirconia ceramics by injection molding and sintering means, and a tapered hole is formed at the center of the rear part of the capillary 4. 3 is polished to a cutting angle of 30 to 60 degrees and a rear surface diameter of 1.0 to 1.2 mm, and then the rear end of the capillary 4 is press-fitted into the fitting hole 7 of the sleeve 6. It is characterized by being fixed.

First, a pilot hole 1a is drilled in the center, a chamfer 2 is applied to the front surface, and a tapered hole 3 is formed in the center of the rear surface. A capillary raw material 4' of a predetermined length is made of zirconia ceramic material. Manufactured by injection molding and sintering means.

After that, the prepared hole 1a of the capillary raw material 4' is polished to form a minute hole 1 for inserting the optical fiber 5a, the outer diameter is polished for centering, and the end face is polished to have a chamfered 2 on the front surface.
The notch angle is 30 degrees, the width is 05 to 0.8 mm, the notch angle of the tapered hole 3 on the rear surface is 30 to 60 degrees, and the rear diameter is 1
．． Finish to 0~1°2mm. The tapered hole 3 may be a combination of a straight hole 3a and a tapered hole 3b.In this way, when the optical fiber 5a is inserted into the microhole 1 of the capillary 4 formed, the insertion operation can be performed extremely smoothly. , the optical fiber 5a will not be damaged.

Next, a true cylindrical stainless steel sleeve 6 which has been subjected to centering and polishing processing in the same manner is manufactured, and the rear end side of the capillary 4 is inserted into the fitting hole 7 at the tip thereof so that their axes coincide with each other. Press-fit and fix the ferrule F to complete the assembly work.

In the ferrule F of the present invention, as shown in FIG.
The optical fiber core 5 enters into the position a and is fixed at that position.
connection stability is increased.

EXAMPLE Hereinafter, one example of implementing the present invention will be explained in order of manufacturing steps with reference to the drawings.

(1) Capillary manufacturing process Using zirconia ceramic as a raw material, injection molding and sintering are used to make a pilot hole 1a in the center as shown in Fig. 2 (1), a chamfer 2 on the front surface, and a chamfer 2 on the rear surface. A raw material 4' having tapered holes 3 formed therein is manufactured.

Of course, the length, outer diameter and prepared hole dimensions of the capillary raw material 4' are made slightly larger in preparation for later polishing.

First, the length of the capillary raw material 4' is 10.6 to 10.7
mm, and then the end face is polished to a predetermined length of 10 mm.

The diameter of the prepared hole 1a of the Shapirari raw material 4′ is 0°11mm.
Then, the diameter of the minute hole for inserting the optical fiber 5a is set to a predetermined diameter by the hole polishing that is performed thereafter.

The diameter of this microhole is approximately 0.1 mm, which is slightly larger than the outer diameter of the optical fiber 5a.

The outer diameter of the capillary raw material 4'' is 2.58 to 2.60 mm, and the outer diameter is polished (centered) to a perfect circle of 2499 mm.

Next, the chamfer 2 made on the front surface of the capillary raw material 4' is
It is intended to facilitate insertion into a cylindrical adapter that connects optical fiber connectors, and a notch angle of 30 degrees with a polished end face and a diameter of 0.5 to 0.8 mm is suitable.

A tapered hole 3 formed at the center of the rear surface of the capillary raw material 4' is for facilitating insertion of the optical fiber 5a, and is concentrically opened to communicate with the microhole 1.

This tapered hole 3 has a small roundness (Ro, 2 mm) at the corner where it intersects with the micro hole 1 in the end face polishing that is performed afterwards.
At the same time, the cutting angle is 30 to 60 degrees and the rear diameter is 1.0 to 1.2 mm.

The embodiment shown in Figure 1.2 has a cutting angle of 30 degrees and a rear diameter of 1.2 degrees. Omm, the embodiment shown in Fig. 3 has a cutting angle of 60 mm.
The diameter of the rear surface is 1.2 mm.

Since the present invention uses injection molding instead of drilling, it is possible to form the tapered hole 3 with an acute angle and a smooth inner surface as described above.

Therefore, the insertion of the optical fiber 5a can be performed extremely smoothly, and there is no risk of damaging the optical fiber 5a. Since the tip of the jacket 5b enters the tapered hole 3 having a rear diameter of 1.0 to 1.2 mm, the stability of the connection of the optical fiber 5 increases.

Through the above steps, capillary raw material 4' is transferred to capillary 4.
is finally completed, but other embodiments of the capillary 4 may be as shown in FIG. 4.5.

That is, a straight hole 3a is provided at the center of the rear part of the capillary 4, and a tapered hole 3b is connected to the inside of this straight hole 3a. The diameter of this straight hole 3a is 1.0 like the tapered hole 3.
~1.2 mm, and the length is lO~2.0 mm. The tapered hole 3b has the same diameter and cutting angle as the tapered hole 3.

Of course, the microhole 1 for inserting the optical fiber 5a, the tapered hole 3b, and the straight hole 3a all communicate concentrically.

In this embodiment, as shown in FIG. 6, when the optical fiber 5a is inserted into the capillary 4, the tip of the jacket 5b completely enters the straight hole 3a, so that the insertion work can be performed extremely smoothly, and the addition and Optical fiber core #i!
5 and the stability of the optical fiber 5a increases when so.

Note that the cutting angle of the tapered hole 3.3b as described above is 3.
The angle of 0 to 60 degrees is selected as the optimum angle for guiding the optical fiber 5a.

Moreover, if the diameter is less than 1.0 to 1.2 mm, it will hinder the entry of the optical fiber core 5, while if it is more than this, the amount of adhesive for fixing will increase and there is a risk that the precision of the fiber will be affected. many.

(2) Sleeve manufacturing process: The process of manufacturing the capillary 4 involves fixing the rear end of the capillary 4 in the correct size.
Using stainless steel, a fitting hole 7 for the capillary 4 is formed at the tip of the large diameter portion 6a, a collar 8 with an engaging recess 8a is formed on the outer periphery of the fitting hole 7, and a collar 8 with an engaging recess 8a is formed in the small diameter portions 6, b. A through hole 9 for the optical fiber coated wire 5 communicating concentrically and a tapered hole 10 for facilitating insertion of the optical fiber coated wire 5 are formed at the rear end thereof.

Note that the outer and inner diameter dimensions of the sleeve 6 are similar to that of the capillary 4.
It is ground with high precision to minimize eccentricity when installed.

(3) Assembly process Finally, an assembly process is performed in which the rear end of the capillary 4 manufactured in the above process is completely fitted into the fitting hole 7 of the sleeve 6 and fixed with adhesive, and the ferrule F is completed.

Further, as actual steps, a step of inserting and fixing the optical fiber core 5 and the optical fiber 5a into the ferrule F and an end face polishing step of simultaneously polishing the tip surfaces of the optical fiber 5a and the capillary 4 are required.

(1) Effects of the Invention As described above, the ferrule for an optical fiber connector according to the present invention is made by injection molding and sintering a capillary with a shape similar to that of a finished product using zirconia ceramics.
It eliminates the need for extremely troublesome and time-consuming operations such as drilling and chamfering, and is extremely suitable for mass production.

In addition, since it is injection molding that does not require a drill rather than conventional extrusion molding, the cutting angle and rear diameter of the tapered hole 3 can be finished with ideal dimensional accuracy of 30 to 60 degrees and 1.0 to 1.2 mm. The optical fiber 5a can be inserted smoothly, and the optical fiber 5a is less likely to be damaged during insertion.

Furthermore, the connection stability of the optical fiber core 5 to the ferrule F is increased.

Furthermore, since the capillary 4 is larger and easier to handle than conventional products, and a partial press-fitting method into the sleeve 6 is adopted, assembly of the ferrule F is also facilitated.

Thus, the present invention has many advantages, such as greatly shortening the processing and assembly time as a whole, improving yields, and mass-producing high-quality products at low cost.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing a state in which an optical fiber core 5 is connected to a ferrule F showing an example of the implementation of the present invention, and FIG.
), (2), and (3) are longitudinal sectional views showing the manufacturing process of the ferrule F of the present invention, FIGS. 3 to 5 are longitudinal sectional views of various capillaries 4, and FIG. 6 is a longitudinal sectional view of the capillary 4 shown in FIG. Vertical cross-sectional views showing the state in which the optical fiber core 5 is connected to the ferrule F used, FIGS. 7(a) to 7(e) are the conventional ferrule F'
FIG. 8 is a partially cutaway side view of a conventional ferrule F'. Main symbols in the diagram: Micro holes...Prepared holes, chamfers 3b, 10...Tapered holes...Straight holes, capillaries, capillary raw materials, optical fiber cores, optical fibers, jackets, sleeves, fitting holes, holes Insertion hole 1 / LA / 2 / 3, A 4 / 5 / 5 A / 5B / 6 / 7 / 8 / 9 / F Ferrule

Claims (2)

[Claims] (1) A microhole 1 for inserting an optical fiber is drilled in the center, a chamfer 2 is provided on the front surface, and the microhole 1 is formed in the center of the rear part.
It consists of a ceramic cylindrical capillary 4 each having a tapered hole 3 that communicates concentrically with the capillary, and a metal or plastic cylindrical sleeve 6 into which the rear side of the capillary 4 is press-fitted. In the method for manufacturing a ferrule for an optical fiber connector, the capillary 4 is made of zirconia ceramics by injection molding and sintering, and the tapered hole 3 at the center of the rear part is cut with a cutting angle of 30 to 60 degrees and a diameter of the rear surface. A ferrule for an optical fiber connector characterized in that the ferrule is polished to a thickness of 1.0 to 1.2 mm, and then assembled by fixing the rear end of the capillary 4 to the fitting hole 7 of the sleeve 6. Production method. (2) The center of the rear part of capillary 4 has a diameter of 1.0 to 1.2
mm, a straight hole 3a with a length of 1.0 to 2.0 mm is provided,
A ferrule for an optical fiber connector according to claim (1), characterized in that a tapered hole 3b having a cut angle of 30 to 60 degrees and the same diameter as the straight hole 3a is connected to the inside of the straight hole 3a. manufacturing method.