JP2001091783A - Slit sleeve for optical communication and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a slit sleeve 10 for optical communication small in a connection loss when an optical fiber connector is composed. SOLUTION: In the slit sleeve 10 for optical communication in which a slit 11 is provided in the longitudinal direction of its cylindrical body, the roundness of the inner peripheral surface 12 is specified to 1 μm or less, moreover the straightness in the longitudinal direction of the inner peripheral surface 12 is specified to 1 μm or less, further the degree of concentricity between the outer peripheral surface 13 and the inner peripheral surface 12 of the slit sleeve 10 is specified to 10 μm or less and moreover the surface roughness of the inner peripheral surface 12 is specified to Rma×0.5 μm or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a split sleeve for optical communication used for connecting optical fibers in optical communication or the like.

[0002]

2. Description of the Related Art As shown in FIG. 3, the structure of an optical connector for connecting optical fibers is such that ferrules 41 each having an optical fiber 40 inserted therein are inserted from both ends of a split sleeve 10 and abutted. The above ferrule 41,
As the material of the split sleeve 10, ceramics such as alumina and zirconia, metals, plastics and the like are used.

As shown in FIG. 2, the conventional general split sleeve has a cylindrical body provided with a slit 11 in the longitudinal direction, and an inner peripheral surface 12 of which is slightly smaller than the outer diameter of the ferrule 41 and is precisely polished. (Japanese Unexamined Patent Application Publication No.
Reference). When the ferrule 41 is inserted into the split sleeve 10, the split sleeve 10 is elastically deformed and slightly spreads, so that the ferrule 41 can be firmly gripped by the inner peripheral surface 12 of the split sleeve 10.

When the split sleeve 10 is formed of ceramics, a ceramic raw material is formed into a cylindrical shape by extrusion or the like, fired, and then the inner and outer peripheral surfaces are ground to form a slit 31 by processing. Was manufactured.

[0005]

However, in the conventional split sleeve 10, when a pair of ferrules 41 into which the optical fiber 40 is inserted are inserted from both ends of the split sleeve 10 and brought into contact with each other, the individual split sleeve 10 The connection loss varies, and the roundness, straightness, concentricity,
There is a problem that it is difficult to obtain stable optical characteristics even if the dimensional accuracy of each part alone such as the inner peripheral surface roughness, the outer diameter dimension, and the inner diameter dimension is improved.

[0006]

In view of the above, the present invention provides
In the optical communication split sleeve provided with a slit in the longitudinal direction of the cylindrical body, the roundness of the inner peripheral surface is 1 μm or less, and the straightness of the inner peripheral surface in the longitudinal direction is 1 μm or less.

That is, it has been found that the above problem can be solved particularly by setting the roundness and straightness within the above ranges.

In the split sleeve, the concentricity between the outer peripheral surface and the inner peripheral surface is 10 μm or less, and the surface roughness of the inner peripheral surface is Rmax 0.5 μm or less.

Further, the present invention is characterized in that, as a method for processing the inner peripheral surface of the split sleeve, after rough polishing by honing processing, final finishing processing is performed by pin polishing.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a split sleeve 10 according to an embodiment of the present invention. The split sleeve 10 is made of a material such as ceramics such as alumina or zirconia, phosphor bronze, or plastics, is provided with a slit 11 in a longitudinal direction in a cylindrical body, and its inner peripheral surface 12 is slightly smaller than the outer diameter of the ferrule to be inserted. It is precisely polished into a circle with a small inside diameter.

As shown in FIG. 3, the split sleeve 10 of the present invention has a ferrule 41 into which an optical fiber 40 is inserted from both sides.
By inserting and abutting each other, an optical connector for coupling the optical fibers 40 to each other can be obtained.

The dimensional accuracy of each part is such that the roundness of the inner peripheral surface 12 is 1 μm or less and the straightness of the inner peripheral surface 12 in the longitudinal direction is 1 μm.
Hereinafter, the concentricity between the outer peripheral surface 13 and the inner peripheral surface 12 is 10 μm or less, and the surface roughness Rmax of the inner peripheral surface 12 is 0.5 μm.
It is as follows.

Here, the reason why the roundness of the inner peripheral surface 12 is set to 1 μm or less is that when the roundness of the inner peripheral surface 12 exceeds 1 μm, a portion of the split sleeve 10 that grips the ferrule of the inner peripheral surface 12 is formed. It is not constant, and conversely the roundness of the inner peripheral surface 12 is infinite
This is because the ferrule 41 is gripped on the entire inner peripheral surface 12 as the distance from the inner peripheral surface 12 increases, and the connection loss can be reduced.

The straightness of the inner peripheral surface 12 in the longitudinal direction is 1 μm.
When the straightness of the inner peripheral surface 12 exceeds 1 μm, when the ferrules 41 are butted from both sides of the split sleeve 10, the center deviation of the optical fibers 40 at the center position of the ferrule end surface occurs, Conversely, as the straightness in the longitudinal direction of the inner peripheral surface 12 approaches zero as much as possible, the ferrules 41 on both sides are fixed on the inner peripheral surface 12 of the split sleeve 10 in a straight line, and the connection loss can be reduced. Because we can.

Next, the concentricity between the outer peripheral surface 13 and the inner peripheral surface 12 is set to 10 μm because the concentricity between the outer peripheral surface 13 and the inner peripheral surface 12 exceeds 10 μm. As a result, the outer peripheral surface of the ferrule 41 cannot be evenly gripped. Conversely, as the concentricity between the outer peripheral surface 13 and the inner peripheral surface 12 approaches zero as much as possible, the inner peripheral surface 12 of the split sleeve 10 becomes uniform in the circumferential direction. This is because the ferrule 41 is gripped in a short time, and the connection loss can be reduced.

Finally, the surface roughness of the inner peripheral surface 12 is calculated as Rmax
The reason why the thickness is set to 0.5 μm or less is that the surface roughness of the inner peripheral surface 12 is R
If the thickness exceeds max 0.5 μm, the portion of the inner peripheral surface 12 of the split sleeve 10 that grips the ferrule is not constant due to the unevenness of the surface, and conversely, as the surface roughness of the inner peripheral surface 12 approaches zero as much as possible, the inner peripheral surface This is because the ferrule 41 is gripped by the entirety of the joint 12, and the connection loss can be reduced.

Accordingly, with the dimensional accuracy of each part of the split sleeve 10, the roundness of the inner peripheral surface 12 is 1 μm or less, the straightness of the inner peripheral surface 12 in the longitudinal direction is 1 μm or less, and the outer peripheral surface 13 and the inner peripheral surface 1
By setting the concentricity with No. 2 to 10 μm or less and the surface roughness of the inner peripheral surface 12 to Rmax 0.5 μm or less, an excellent effect can be obtained in connection loss, which is the most important optical characteristic.

Here, a method of measuring each dimension will be described.

The roundness is measured by using a roundness measuring device and rotating the split sleeve 10 while the stylus is in contact with the inner peripheral surface 12 of the split sleeve 10 to measure the deflection of the stylus. The straightness is measured by using a contact-type shape measuring instrument, by bringing a stylus into contact with the inner peripheral surface 12 of the split sleeve 10, and measuring the deflection of the stylus while moving the stylus in the longitudinal direction. The concentricity is measured by using a concentricity measuring device, rotating the split sleeve 10 on the V-groove, and measuring the displacement of the inner peripheral surface 12 on the enlarged image. The surface roughness of the inner diameter surface 12 is measured by using a contact-type shape measuring instrument, by bringing a stylus into contact with the inner peripheral surface 12 of the split sleeve 10 and measuring the deflection of the stylus while moving the stylus in the longitudinal direction.

Next, a method for manufacturing the split sleeve 10 of the present invention will be described.

A raw material containing zirconia as a main component and containing yttria, alumina, titania, calcia and the like is formed into a cylindrical shape in advance by extrusion molding, press molding, or injection molding, and is baked and hardened in a firing step. Next, the outer peripheral surface 13
Is ground with a diamond grindstone using a cylindrical grinder, and the inner peripheral surface 12 is polished by honing using a diamond grindstone and pin polishing using diamond abrasive grains so as to have a predetermined inner diameter. Finally, the slit 11 is ground with a diamond grindstone using a surface grinder.

The polishing of the inner peripheral surface 12 is characterized in that both the honing and the pin polishing are performed, whereby the dimensional accuracy described above can be obtained for the first time. Hereinafter, the details will be described with reference to FIG.

FIG. 4 (a) is a conceptual diagram showing honing processing. A diamond grindstone 31 is attached to a tapered portion of a horn 30 having a tapered tip, and the horn 30 is rotated to fix a fixing jig 32. The diamond grindstone 31 of the horn 30 is brought into contact with the inner diameter of the split sleeve 10 fixed to the horn 30, and the load of the horn 30 is applied to the inner diameter of the split sleeve 10.

By the way, in the split sleeve 10 subjected to only the honing, the straightness of the inner peripheral surface 12 is poor, and the connection loss is also poor. The reason why the straightness of the inner peripheral surface 12 is deteriorated is that both the horn 30 and the fixing jig 32 have high rigidity, and the concentricity between the inner diameter center of the split sleeve 10 and the center of the horn 30 is zero.
This is because the displacement does not affect the longitudinal undulation of the inner peripheral surface 12 of the split sleeve 10.

FIG. 4 (b) is a conceptual diagram showing the polishing of a pin. Diamond abrasive grains 21 mixed with an oily slurry are applied to a pin 20 having a tapered tip, and the pin 20 is rotated. The tapered surface of the pin 20 is brought into contact with the inner peripheral surface 12 of the split sleeve 10 fixed to the fixing jig 22,
A load is applied to the split sleeve 10 in the direction of the tapered surface of the pin 20.

The split sleeve 10 polished only by the pin has poor roundness of the inner peripheral surface 12 and poor average connection loss. The reason why the roundness of the inner peripheral surface 12 is deteriorated is that when a load is applied to the split sleeve 10, the load is not completely parallel to the pin, so that the eccentricity is equal to the roundness of the inner peripheral surface 12 of the split sleeve. It is affecting the degree.

On the other hand, in the inner peripheral surface processing method of the present invention, the inner peripheral surface 12 is first roughly polished by honing shown in FIG. By performing the finishing, both the roundness of the inner peripheral surface and the cylindricity of the inner peripheral surface become 1 μm or less, and the connection loss can be significantly reduced.

The processing method of the present invention is an example. In addition to ceramics, the above-described dimensions can be applied to a phosphor bronze split sleeve formed by bending a flat plate by precision press working or a plastics split sleeve formed by precision injection molding. The same effect can be obtained by any method as long as accuracy can be obtained.

Next, in a processing method for setting the concentricity of the inner peripheral surface 12 and the outer peripheral surface 13 of the split sleeve 10 to 10 μm or less, a rod-shaped metal pin is inserted into the inner peripheral surface 12 and the outer peripheral surface of the metal pin is used as a reference. This is achieved by cutting the outer diameter of the outer peripheral surface 13 of the split sleeve 10.

The inner surface 12 has a surface roughness Rmax0.
The method of reducing the diameter to 5 μm or less is achieved by setting the average particle diameter of the diamond abrasive grains 21 to 1 to 2 μm in the pin polishing as the final processing of the inner peripheral surface 12.

[0032]

EXAMPLE Here, an experiment was conducted by the following method.

As an embodiment of the present invention, the inner peripheral surface is shown in FIG.
After rough polishing by honing shown in FIG. 4, a split sleeve made of zirconia, which is finally finished by pin polishing shown in FIG. 4B, is prepared. As a comparative example, a split sleeve made of zirconia, which is finally finished only by the conventional honing, And a zirconia split sleeve that was finally polished only by pin polishing was prepared.

The inside diameter of each of the three types of split sleeves is 2.49.
3 mm, outer diameter is 3.2 mm, length is 11.4 mm, 100 pieces are prepared for each, and the roundness of the inner circumferential surface 12, the straightness of the inner circumferential surface 12, the concentricity of the inner and outer circumferential surfaces, the inner circumference The surface roughness and connection loss of the surface were measured. The maximum value was calculated for the roundness of the inner peripheral surface, the straightness of the inner peripheral surface, the concentricity of the inner and outer peripheral surfaces, and the surface roughness of the inner peripheral surface, and the average value was calculated for the connection loss.

As the ferrule into which the optical fiber used for the measurement was inserted, the ferrule in which the concentricity between the core portion of the optical fiber and the outer peripheral surface of the ferrule was set to 0 was used.

Table 1 shows the results. As described above, the split sleeve which has been processed to the final finish only by the conventional honing process has a poor straightness of the inner peripheral surface and a poor average value of connection loss. or,
In the case of the split sleeve which has been performed from rough polishing to final polishing only by conventional pin polishing, the roundness of the inner peripheral surface is poor, and the average value of connection loss is also poor.

On the other hand, in the present invention, the roundness of the inner peripheral surface,
Both the cylindricity of the inner peripheral surface is 1 μm or less, and the average value of the connection loss is remarkably small and a good value.

[0038]

[Table 1]

FIG. 5 shows the distribution of connection loss of the above three types of split sleeves.

As described above, the split sleeve of only the honing process and the split sleeve of only the pin polishing process have a large splice loss value and a large variation, whereas the split sleeve of the present invention has an average splice loss value. It can be confirmed that the variation is small as well as small.

Therefore, after the inner peripheral surface of the optical communication split sleeve provided with a slit in the longitudinal direction of the cylindrical body is roughly polished by honing, and finally finished by pin polishing, the inner peripheral surface is perfectly round. Both the degree and the straightness of the inner peripheral surface can be reduced, and an excellent effect on the connection loss value, which is the most important optical characteristic, can be obtained.

[0042]

As described above, according to the present invention, in an optical communication split sleeve provided with a slit in the longitudinal direction of a cylindrical body, the roundness of the inner peripheral surface is 1 μm or less, and the longitudinal direction of the inner peripheral surface is reduced. By setting the straightness to 1 μm or less, the connection loss can be reduced and the variation thereof can be reduced.

Further, the inner peripheral surface can be processed by rough finishing by honing and then by final finishing by pin polishing, whereby the split sleeve having the above surface accuracy can be easily obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an optical communication split sleeve of the present invention.

FIG. 2 is a perspective view showing an optical communication split sleeve of the present invention.

FIG. 3 is a cross-sectional view showing a structure of a general optical connector for connecting optical fibers to each other.

FIG. 4A is a conceptual diagram illustrating pin polishing, and FIG. 4B is a conceptual diagram illustrating honing processing.

FIG. 5 is a graph showing a distribution state of connection loss of an optical connector using the optical communication split sleeve of the present invention and a comparative example.

[Explanation of symbols]

 10: split sleeve 11: slit 12: inner peripheral surface 13: outer peripheral surface t: wall thickness 20: pin 21: diamond abrasive grain 22: fixing jig 30: horn 31: diamond grinding stone 32: fixing jig 40: optical fiber 41: ferrule

Claims (3)

[Claims] 1. An optical communication split sleeve provided with a slit in a longitudinal direction of a cylindrical body, wherein an inner peripheral surface has a roundness of 1 μm or less, and an inner peripheral surface has a longitudinal straightness of 1 μm or less. Characteristic split sleeve for optical communication. 2. The split sleeve for optical communication according to claim 1, wherein the concentricity between the outer peripheral surface and the inner peripheral surface is 10 μm or less, and the surface roughness of the inner peripheral surface is Rmax 0.5 μm or less. 3. An optical communication split sleeve in which a slit is provided in a longitudinal direction of a cylindrical body, wherein the inner peripheral surface is roughly polished by honing and then subjected to final finishing by pin polishing. Method of manufacturing split sleeve.