JP2001066460A - Sleeve for optical fiber connection and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the discoloration and corrosion of the surface of a cylindrical metallic sleeve by forming a protective film on this surface. SOLUTION: A belt-like flat plate 10 of phosphor bronze is provided with a pair of pilot holes 11a and 11b. This belt-like flat plate 10 is blanked to a rectangular shape to form an external form of a work 13 connected at two points to a frame 12. Next, the work 13 is gradually bent to form the cylindrical sleeve 15 having a straight slit 14. The sleeve is then disconnected by cutting the sleeve at the two points connected to the frame 12. The protective film is formed on the inner peripheral surface of the cylindrical metalic sleeve 14 formed with the slit in the longitudinal direction. While the method of forming the protective film is representatively metal plating, the plating of non-metals, such as ceramics is possible as well. In such a case the nonmetallic surface on the flat plate is subjected to plating and, therefore, the entire surface is coated with a uniform film thickness and may be smoothly finished.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sleeve for connecting an end of an optical fiber and a method for manufacturing the same.

[0002]

2. Description of the Related Art In general, when optical fibers are connected to each other in an optical communication means using an optical fiber, an end of the optical fiber is covered with a cylindrical body called a ferrule, and this ferrule is covered with a cylindrical sleeve. The optical fiber is inserted by inserting it from both sides, and the ends of the optical fiber are connected by abutting the front surface of the ferrule from both sides.

FIG. 4 shows the shape of a general sleeve 1, which is formed as a cylindrical body having a linear slit 2 formed in the longitudinal direction. Since the slit 2 is provided, elasticity is imparted in the circumferential direction. When the ferrule 4 attached to the end of the optical fiber 3 is mounted on the sleeve 1, the ferrule 4 is elastically held.

[0004]

Incidentally, zirconia ceramics and phosphor bronze are often used as the material of the sleeve 1. Zirconia ceramics have the property of being stable against rust, discoloration, and the like, and also have the characteristic that dust is unlikely to adhere thereto, but have the problem of high price. On the other hand, phosphor bronze has a moderate elasticity and is inexpensive as compared with zirconia ceramics. However, it has problems such as discoloration of the surface and corrosion in long-term use.
Further, when the surface of the sleeve 1 is rough, the outer peripheral surface of the ferrule 4 may become black due to phosphor bronze metal powder while the ferrule 4 is being detached several times, or dust may adhere thereto. There was a risk of causing light loss.

Accordingly, an object of the present invention is to form a protective coating on the inner peripheral surface of a cylindrical metal sleeve, thereby avoiding the problems when using a metal sleeve such as the above-mentioned phosphor bronze, and using zirconia. An object of the present invention is to provide an inexpensive metal sleeve having properties comparable to ceramics. By the way, the conventional method of manufacturing a metal sleeve is a lace process in which a drill is cut into a round bar using an automatic machine and then a slit is formed, or a pipe that is pre-processed to the diameter of the sleeve is formed at predetermined lengths. Since the pipe was cut and slit into the pipe, uniform plating could not be formed on the surface of the sleeve processed into a cylindrical shape.

[0006]

In order to solve the above-mentioned problems, the present inventor has proposed a method of forming a metal sleeve by press working, in which the surface of the sleeve (the inner peripheral surface and the outer peripheral surface) is hardened. By forming the protective film, the above-mentioned problems of the conventional metal sleeve are avoided. More specifically, the invention according to claim 1 is a cylindrical metal sleeve having a slit formed in a length direction thereof, wherein a protective coating is formed on an inner peripheral surface thereof. The above-mentioned problem has been solved by the connecting sleeve.

According to the present invention, by forming a protective coating on the inner peripheral surface of the metal sleeve, the surface of the sleeve is improved, and the surface can be prevented from being discolored or corroded.
Further, dust and metal powder hardly adhere to the surface of the sleeve, and the surface of the ferrule does not become black, so that the communication performance is not impaired.

According to a second aspect of the present invention, in the optical fiber connecting sleeve according to the first aspect, the slit is formed in a wavy shape in the length direction.

According to the present invention, since the ferrule is held so as to be embraced alternately from the left and right, stable mounting can be obtained.

According to a third aspect of the present invention, in the optical fiber connecting sleeve according to the first aspect, the protective coating is formed by plating.

According to the present invention, the protective film can be formed by a simple means. As the plating method, for example, electroplating, chemical plating, metal spraying, room temperature diffusion / penetration plating, or the like can be used.

According to a fourth aspect of the present invention, in the optical fiber connecting sleeve according to the third aspect, the protective coating is a metal plating layer or a ceramic alloy layer.

According to the present invention, the surface hardness and the corrosion resistance can be increased, and the same properties as those of a conventional sleeve made of zirconia ceramics can be obtained.

According to a fifth aspect of the present invention, there is provided a method of forming a cylindrical metal sleeve having a slit formed in a longitudinal direction by press working. A method for manufacturing an optical fiber connection sleeve, wherein the sleeve is formed.

According to the present invention, by employing press working, a protective film having high surface hardness and high corrosion resistance can be easily formed on a flat work in the middle of press working.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an optical fiber connecting sleeve according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a sleeve forming step in the progressive press step in order. In step 1, a pair of pilot holes 11a,
11b, the step 2 and the step 3
Forming a contour of a work 13 connected to the frame 12 at two points by punching the work into a rectangular shape. In steps 4 to 6, a cylinder provided with a linear slit 14 by gradually bending the work 13 Forming a sleeve 15 in the shape of
Step 7 shows a step of cutting the sleeve 15 by cutting two portions connected to the frame 12.

In the present invention, a protective film is formed on the work 13 between the steps 3 and 4. At this stage, work 13
Since a flat surface is secured, it is easy to form a protective coating, and a protective coating having a uniform thickness can be formed on both surfaces of the work 13. Therefore, in the progressive press step, when the step 3 is completed, the press working is temporarily interrupted to move to the protective coating forming step, and after that, the process is returned to the progressive press step 4 and the remaining steps are performed. Then, the sleeve 15 having a protective coating formed on the surface (the inner and outer peripheral surfaces of the cylinder) is formed.

As a method of forming the protective film, metal plating is typical, but non-metal such as ceramics can also be plated. Plating is performed in various ways to improve the properties of the metal surface to be plated, such as increasing the surface hardness or smoothing the surface, but all methods are performed on a flat metal surface, so a cylindrical body is used. Unlike plating, the entire surface is coated with a uniform film thickness,
Also, it can be finished very smoothly. In the present invention, electroplating, chemical plating, metal spraying, room temperature diffusion / penetration plating, or the like can be employed as a metal plating treatment method. Also, non-metals such as ceramics can be plated using room temperature diffusion / penetration plating.

In the electroplating, the surface of the sleeve 15 can be plated with gold, silver, nickel, chrome, or the like. Since gold plating is soft as it is, it is desirable to perform plating as an alloy with silver or copper. Further, since silver plating is directly affected by sulfides and darkens, it is desirable to further thin-plate rhodium thereon. On the other hand, in nickel plating, plating can be easily performed by plating over copper plating. Further, chromium plating has particularly high surface hardness, and also has high wear resistance and heat resistance.

On the other hand, chemical plating utilizes substitution by a difference in ionization tendency of a metal and chemical reduction by a reducing agent,
A method of plating a metal without relying on an electric field, and is used when performing nickel plating, chrome plating, or the like. In addition, sodium hypophosphite is widely used as a reducing agent. In both of the electroplating and the chemical plating, the work 13, which has been completed up to the step 3, is continuously passed through a plating bath filled with a plating solution while being connected to the frame 12. A hoop plating method is used.

Further, in the metal spraying method, a metal powder or a metal wire is melted at a nozzle portion of a spraying machine and blown off using compressed air or hydrogen gas, and a metal protective film is attached and solidified on the surface of the work 13. It is a way to make it. The metal material used as the metal powder or the metal wire has a hardness equal to or higher than the phosphor bronze hardness.

In the room temperature diffusion / penetration plating method, a metal powder or a ceramic powder is sprayed onto the surface of the work 13 at a high speed to raise the surface temperature, and the elements in the composition of the metal powder or the ceramic powder are transferred to the work 13. The surface hardness and corrosion resistance can be increased by diffusing and penetrating the metal surface of No. 13 to form an alloy layer on the surface. In particular, when a ceramic powder is used, an alloy layer with the ceramic is formed, so that properties equivalent to those of a conventional sleeve made of zirconia ceramics can be obtained. Note that chromium or cobalt is used as the metal powder, and zirconia or alumina is used as the ceramic powder.

In the above-described plating step, a hard metal plating layer is formed on the surface of the work 13 to a uniform thickness or a ceramic alloy layer is formed. The metal plating layer and the alloy layer do not peel off from the surface of the sleeve 15 just to the extent that the bending in the step 6 is performed. Therefore, after such a plating step, even if the original material is phosphor bronze, the surface is not discolored or corroded even after long-term use, and the surface hardness is high and smooth. Therefore, metal powder of phosphor bronze, dust and the like hardly adhere to the outer peripheral surface of the ferrule.

In the above-described embodiment, the case where the metal plating layer or the ceramic alloy layer is applied to the surface of the work 13 during the press working step has been described. The same applies to the case where the above-described plating step has been completed. Even in this case, the metal plating layer is not peeled off by the punching process from the pressing step 1 to the step 3. The present invention is also applicable to the case where a protective film is formed on the surface of the sleeve 15 by means other than the plating described above.

FIGS. 2 and 3 show a second embodiment of the present invention. Sleeve 16 in this embodiment
Has a slit 17 formed in a wavy shape in the longitudinal direction. As shown in FIG. 3, in the step of punching and forming the outer shape of the work 18 on the strip-shaped flat plate 10 as shown in FIG. 3, the convex portion 19 is formed on the left central portion of the work 18 and the corresponding concave portion 20 is formed on the right central portion. By forming, the slit 17 having a wavy shape as shown in FIG. 2 can be formed at the time of bending. By forming such a wavy slit 17, the ferrule can be held so as to be embraced alternately from the left and right, so that more stable mounting is possible.

[0026]

As described above, according to the optical fiber connecting sleeve of the present invention, the protective coating is formed on the inner peripheral surface of the cylindrical metal sleeve having the slit formed in the longitudinal direction. In addition, the metal surface of the sleeve is improved, and the surface can be prevented from being discolored or corroded. Further, dust and metal powder hardly adhere to the surface of the sleeve, and the surface of the ferrule does not become black, so that the communication performance is not impaired.

Further, according to the method of manufacturing an optical fiber connecting sleeve according to the present invention, a cylindrical metal sleeve having a slit formed in a longitudinal direction is formed by pressing, and a bending process during the pressing is performed. Since the protective film is formed on the work when the process starts, a film having high surface hardness and high corrosion resistance can be surely formed by a simple method.

[Brief description of the drawings]

FIG. 1 is a process diagram of press working of an optical fiber connecting sleeve according to a first embodiment of the present invention.

FIG. 2 is a perspective view of an optical fiber connection sleeve according to a second embodiment of the present invention.

FIG. 3 is a view showing one step of press working of an optical fiber connection sleeve according to the second embodiment.

FIG. 4 is a perspective view showing a general use example when an end of an optical fiber is connected to a sleeve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Band-shaped flat plate 12 Frame 13,18 Work 14,17 Slit 15,16 Sleeve 19 Convex part 20 Concave part

Claims (5)

[Claims] 1. An optical fiber connection sleeve, comprising: a cylindrical metal sleeve having a slit formed in a longitudinal direction, wherein a protective coating is formed on an inner peripheral surface of the sleeve. 2. The optical fiber connecting sleeve according to claim 1, wherein said slit is formed in a wave shape in a longitudinal direction. 3. The optical fiber connection sleeve according to claim 1, wherein said protective coating is formed by plating. 4. The optical fiber connection sleeve according to claim 3, wherein said protective coating is a metal plating layer or a ceramic alloy layer. 5. A method for forming a cylindrical metal sleeve having a slit formed in a longitudinal direction by press working, wherein a protective film is formed on a work when a bending process is performed during press working. A method for producing an optical fiber connection sleeve, characterized by comprising: