EP0231397A1

EP0231397A1 - Grinder for core of optical connector and core grinding method

Info

Publication number: EP0231397A1
Application number: EP86904925A
Authority: EP
Inventors: Toshihiro Furukawa Electric Co. Ltd. Ochiai; Akihiro Furukawa Electric Co. Ltd. Ohtake; Izumi Nippon Telegram & Telephone Co. Ltd Sankawa
Original assignee: Furukawa Electric Co Ltd; Nippon Telegraph and Telephone Corp
Current assignee: Furukawa Electric Co Ltd; Nippon Telegraph and Telephone Corp
Priority date: 1985-08-07
Filing date: 1986-08-07
Publication date: 1987-08-12
Anticipated expiration: 2006-08-07
Also published as: WO1987000785A1; KR930007108B1; EP0231397A4; CA1322457C; NZ217135A; DE3684135D1; JPS6234762A; KR870700454A; EP0231397B1; AU6200086A

Abstract

Technique for grinding an end surface of a core (2) of an optical connector used for connecting an optical fiber (11), to grind the same into a convex surface. A grinder (3) is proy- ided with at least a layer (4) of a low-elasticity material, and a grinding layer (5) laminated unitarily on the upper surface of the layer (4). The JIS-A hardness and Shore hardness of the layer (4) of the low-elasticity material are set to be not less than 50° and not more than 60°, respectively. When the surface of such a grinder and the end surface of the core (2) of an optical connector are brought into contact with each other with a suitable pressing force, the surface of the grinder (3) Is recessed to form a concave surface. Accordingly, the end surface of the core (2) of the connector can be ground into a convex surface by utilizing this recession.

Description

TECHNICAL FIELD

This invention relates to a grinder for optical connector ferrule used to connect optical fibers to one another or an optical connector to other optical components in a convex spherical shape, and a method for grinding the end face of the ferrule.

BACKGROUND ART

Optical connectors have been used to connect optical fibers to one another or an optical connector to other optical components with reproducibility.
A general optical connector has ferrule, and other component in combination. When this optical connector is attached to an optical fiber, the ferrule is attached to the outer periphery of the end of a predetermined optical fiber, the end face of the ferrule is then ground together with the . end of the optical fiber, and they are then associated in other connector component.
In this case, the end face of the ferrule and the end of the optical fiber are ground to reduce a connecting loss.
A physically contacting method which has been recently voted has the step of directly and physically contacting only the ferrule of optical fibers when connecting the optical fibers through an optical connector to reduce the connecting loss to smaller value.
To periorm this physically contacting method, it is necessary to grind the end face of a ferrule in a convex spherical shape at grinding time, i.e., when grinding the end face of the ferrule together with the end of an optical fiber, and to project the ferrule of the optical fiber disposed at the axial center of the end face oi the ferrule from the other portion.
Means shown in Fig. 7 is a representative example of grinding the end face of the ferrule of an optical connector in a convex spherical shape.
When grinding according to the grinding means in Fig. 7, a grinder 1 hving a recess grinding surface lA is rotated by a grinder rotating unit (not shown), the ferrule 2 of the optical connector is rotated by a ferrule rotating unit (not shovn), the end side of the ferrule is rocked (in a pendulum motion) through a ferrule rocking unit (not shown), and the end face of the ferrule 2 is then ground in a convex spherical shape in this moving state while pressing the end face of the ferrule 2 to the grinding surface 1A of the grinder 1.
In the conventional example described above, not only the grinder rotating unit and the ferrule rotating unit but also the ferrule rocking unit are required. Thus, a facility cost for grinding is increased, and four systems such as the rotation of the grinder, the rotation of the ferrule, the rocking of the ferrule and the pressing force of the ferrule to the grinder must be controlled. Therefore, the controlling difficulty is enhanced, and accurate controllability is required for the rocking motion of the ferrule to form a desired convex sphere surface on the end face of the ferrule.
An object of this invention (first embodiment) is to provide a grinder adapted to grind the end face of the ferrule of an optical connector in a convex spherical shape.
Another object of this invention (second embodiment) is to provide the grinder which has sufficient strength and can be readily operated.
Still another object of the invention (third embodiment) is to provide a method of grinding the end face of the ferrule of the optical connector in a predetermined convex sphere surface by a simple control.

DISCLOSURE OF THE INVENTION

In order to achieve the object of the first embodiment of the invention, there is provided according to the invention a grinder for grinding the end face of the ferrule of an optical connector in a convex spherical shape comprising a low-elastic substance layer and a grinding layer laminated on the surface of the low-elastic substance layer formed on the grinder in such a manner that the hardness of the low-elastic substance layer is defined in a range equal to or larger than 50' of JIS-A hardness to 60' or less of Shore hardness.
When the end face of the ferrule of the optical connector is ground through the grinder of the first embodiment, the grinder and the ferrule are respectively rotated to press the end face of the ferrule of the optical connector to the surface of the grinder. In this case, the ferrule is held perpendicularly to the surface of the grinder, and the end face of the ferrule is ground in this state.
The grinder of the first embodiment comprises a low-elastic substance layer and a grinding layer laminated on the surface of the low-elastic substance layer to provide an elastically deformable laminated layer structure. Thus, when the end face of the ferrule is pressed in contact on the surface of the grinder as described above, the surface of the grinder pressed with the end face of the ferrule is recessed, and the end face of the ferrule is ground in a predetermined shape by the recessing effect.
More specifically, since the grinding layer and the low-elastic substance layer are partly elastically deformed by the pressing force of the end face of the ferrule to cause the surface of the grinder to be formed in a recess spherical shape, the end face of the ferrule is ground similarly to the state pressed by the grinding surface having a concave sphere surface, and the end face of the ferrule is thus finished in the opposite shape to the recess sphere surface, i.e., in the convex sphere surface.
In this case, the radius of the convex sphere surface (the end face of the ferrule) is determined mainly according to the hardness of the low-elastic substancp layer and the pressing force of the end face of the ferrule to the surface of the grinder, and since the hardness of the low-elastic substance layer is determined in a range equal to or higher than 50' of JIS-A hardness to 60° or less of Shore hardness, the preferable convex sphere surface can be formed as will be described in more detail later.
To achieve the object of the second embodiment of the invention, there is provided according to the invention a grinder for grinding the end face of the ferrule of an optical connector in a convex spherical shape comprising a low-elastic substance layer, a grinding layer laminated integrally on the surface of the low-elastic substance layer, and a hard substance layer laminated on the back surface of the low-elastic substance layer in such a manner that the hardness of the low-elastic substance layer is defined in a range equal to or higher than 50' of JIS-A hardness to 60 or less of Shore hardness.
The grinder of the second embodiment of the invention can be used similarly to the first embodiment to grind the end of the ferrule of the optical connector in a preferable convex spherical shape, and since the grinder has the hard substance layer, its strength is proved by the hard substance layer, and the grinder can be readily attached to or detached from a grinder rotating unit.
To achieve the object of the third embodiment, there is provided according to the invention a method of grinding the end face of the ferrule of an optical connector in a convex spherical shape by a grinder having at least a low-elastic substance layer and a grinding layer laminated integrally on the surface of the low-elastic substance layer in such a manner that the hardness of the low-elastic substance layer is defined in a range equal to or higher than 50° of JIS-A hardness to 60° or less of Shore hardness, comprising the steps of rotating the grinder and the ferrule at the axial centers thereof as a center, and pressing the end face of the ferrule held perpendicularly to the surface of the grinder to recess the surface of the grinder, thereby grinding the end face of the ferrule in the convex spherical shape.
According to the grinding method of the third embodiment, the grinder defined on the surface thereof in such a manner that the hardness of the grinding layer is defined in a range equal to or higher than 50° of JIS-A hardness to 60° or less of Shore hardness is used, and the end face of the ferrule is ground in the predetermined shape, while recessing the surface of the grinder by the end face of the ferrule pressed to the grinder. Therefore, the surface of the grinder of rotating state may be contacted under a suitable contacting pressure with the end face of the ferrule, and it is not accordingly necessary to move the ferrule in a special manner while grinding, but the contacting pressure of the ferrule to the rotating grinder in an ordinary state may be merely controlled to finish the end of the ferrule in a predetermined convex spherical shape by a simple control.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a lateral sectional view showing a first embodiment of a grinder according to the present invention, Fig. 2 is a lateral sectional view showing a second . embodiment of a grinder according to the invention, Figs. 3 and 4 are side and plan views showing an example of the grinding arrangement using the grinder of the invention, Fig. 5 is a view showing the relationship between the radius of convex sphere surface (of the end face of the ferrule) and the hardness of the low-elastic substance layer, Fig. 6 is a view showing the relationship between the radius of convex sphere surface and the contact loss, and Fig. 7 is an explanatory view of a conventional grinding method.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment of a grinder and a grinding method according to the present invention will now be described in more detail with reference to the accompanying drawings.
A grinder 3 shown in Fig. 1 of the first embodiment of the invention comprises a low-elastic substance layer 4, and a grinding layer 5 laminated integrally on the surface of the low-elastic substance layer 4.
The low-elastic substance layer 4 is formed of an arbitrary low-elastic material such as a soft rubber, a soft plastic or a composite material thereof, and defined in the hardness in a range equal to or higher than 50° of JIS-A hardness to 60° or less of Shore hardness.
The grinding layer 5 is formed, for example, of a diamond lapping film.
The low-elastic substance layer 4 and the grinding layer 5 are integrally laminated through suitable means as will be described below.
The means includes, for example, bonding means of a bonding agent, thremal fusion-bonding means of a hot press or hot melt, or clamping means of a clamp such as a bolt and a nut, or a clip (a spring clip on a calking clip).
The bonding means and the thermal fusion-bonding means of the abovementioned means employ known method suitably.
When the clamping means employ the bolt and the nut, the low-elastic substance layer 4 and the grinding layer 5 are integrally laminated through the bolt which penetrates the layers 4 and 5 and the nut which is clamped with the bolt, and when the clip is used, both the layers 4 and 5 are engaged by the clip at the edges thereof.
A plate-like hard substance layer may be detachably laminated as required on the lower surface of the low-elastic substance layer 4 in the grinder 3.
In this grinder 3, when the end face of the ferrule 2 of the optical connector is pressed to the surface of the grinder 3, the grinder 3 has a property that the pressed portion of the grinder 3 is recessed by the pressing force of the end face of the ferrule 2 to readly grind the end face of the ferrule by this property in a convex spherical shape.
The grinder 2'shown in Fig. 2 is constructed according to the second embodiment of the invention, and not only comprise a low-elastic substance layer 4 and a grinding layer 5 integrally laminated, but comprises a hard substance layer 20 integrally laminated on the back surface of the low-elastic substance layer 4.
A low-elastic substance layer 4 and a grinding layer 5 in Fig. 2 are defined the same as those which have been r already described with respect to the first embodiment in Fig. 1 in such a manner that the hardness of the low-elastic substance layer 4 is defined in a range equal to or higher than 50' of JIS-A hardness to 60' or less of Shore hardness.
The hard substance layer 20 is formed, for example, of arbitrary material such as metal, hard rubber, hard plastic, fiber reinforced plastic, reinforced glass, ceramics or composite material thereof.
Means for integrally laminating the low-elastic substance layer 4, the grinding layer 5 and the hard substance layer 20 suitably include bonding means, thermal fusion-bonding means, or clamping means.
Figs. 3 and 4 show a concretely modified example of a grinding machine in which the grinder 3 of Fig. 1 is attached.
The grinding machine has a rotary disc 6 rotatably driven in a horizontal state, which disc 6 is rotated about its rotational shaft 7 through a motor (not shown) and its transmission system (not shown).
The grinder 3 having the abovementioned property is attached to the upper surface of the rotary disc 6.
A supporting plate 9 which is extended on the grinder 3 and reciprocates circularly in a horizontal direction is provided on a stand 8 disposed perpendicularly to the disc 6 adjacently.
The plate 9 rotatably supports a ferrule holder 10 on the upper surface at the end side, and places a ferrule rotating mechanism 12 for rotating the ferrule holder 10 around its axial center on the plate 9.
The ferrule rotating mechanism 12 has a motor 14 supported through a bracket 13 on the plate 9, a pulley 16 supported to the output shaft 15 of the motor 14, and an endless belt 17 engaged over the pulley 16 and the pulley 10A of the holder 10.
The ferrule 2 of the optical connector is mounted on the outer periphery of the end of the optical fiber 11, pressed on the surface of the grinder 3 rotatably through the plate 9, and detachably set to the center of the ferrule holder 10.
When the grinding method of the third embodiment of the invention is executed by the grinding machine of Figs. 3 and 4 in which the grinder 3 is attached and the ferrule 2 of the optical connector is set as described above, i.e., when the ferrule the method is performed as below.
The end face of the ferrule 2 to be ground is pressed to the surface of the grinder 3, and the surface of the grinder 3 pressed with the end face of the ferrule is recessed by the pressing force.
Then, the ferrule 2 held through the ferrule holder 10 in this state described above is rotatably reciprocated at 360' or larger by the ferrule rotating mechanism 12, and the grinder 3 is simultaneously rotated in an arbitrary one direction such as in a counterclockwise direction.
When the end face of the ferrule is ground while partly recessing the surface of the grinder 3 by the end face of the ferrule 2, the edge of the end face of the ferrule 2 is gradually not ground by the recessed surface, and recessed surface gradually changes in the shape, and the end face of the ferrule 2 is eventually ground in a convex spherical shape.
It is preferable to move the supporting plate 9 to alter the position of the ferrule 2 on the grinder 3 at such grinding time, and thus prevents the grinding surface of the grinder 3 from local and concentrical wearing.
When grinding the ferrule the radius R of the end face (convex sphere surface) of the ferrule is determined by the hardness of the low-elastic substance layer 4 and the pressing force of the ferrule 2 to the grinder.
Fig. 4 shows the relationship between the hardness of the low-elastic substance layer 4 made of urethane of 1 mm thick and the radius R of the convex sphere surface.
In Fig. 5, plotted small circles designate example by a plastic ferrule and plotted triangles indicate example by metal-ceramic composite ferrule.
The range of the hardness of the low-elastic substance layer 4 of the invention can be reliably expressed with JIS-A hardness and Shore hardness. Accordingly, even in the example of Fig. 5, the hardness of the low-elastic substance layer 4 is indicated with both the hardnesses.
Fig. 6 shows the relationship between the radius R of the convex sphere surface and the connecting loss of the connector.
As apparent with reference to Fig. 6, it is understood that stable physical contact is provided with R ₌ 250 mm or less in case of the plastic ferrule, and with R = 150 mm or less in case of the metal-ceramic composite ferrule.
As apparent by referring to Fig. 5, the conditions that the preferable value of the radius R of the end face (convex sphere surface) of the ferrule is such that the hardness of the low-elastic substance layer 4 is defined in a range equal to or higher than 50° of JIS-A hardness to 60° or less of Shore hardness.
If the hardness of the low-elastic substance layer 4 is less than 50° of JIS-A, it was confirmed that the end face of the optical fiber was not preferably ground.
From the abovementioned result, the hardness of the low-elastic substance layer 4 is concluded to be defined in a range equal to or higher than 50° of JIS-A hardness to 60° or less of Shore hardness.
When the method of the third embodiment of the invention is executed by the grinder 3 in Fig. 2, i.e., when the grinder 3 of Fig. 2 is used as in Figs. 3 and 4, the end face (convex sphere surface) of the ferrule can be ground to expect the stable physical contact, thereby satisfying the strength of the grinder itself and the handling easiness.
In the method of Fig. 3 and 4 described above, the grinder 3 is held at a predetermined position and the end face of the ferrule 2 is pressed in contact on the surface of the grinder 3 disposed at the predetermined position. However, this invention is not limited to the particular embodiment. For example, the surface of the grinder 3 may be pressed to the end face of the ferrule 2 disposed at a predetermined position, or relative pressing forces may be acted on both the ferrule 2 and the grinder 3.

INDUSTRIAL APPLICABILITY

Since the grinder of the first embodiment is constituted by integrally laminating the grinding layer on the surface of the low-ealstic substance layer having a feature in the hardness, the surface of the grinder is recessed at the pressed portion when the end face of the ferrule of the optical connector is pressed to the surface of the grinder, and the end face of the ferrule can be ground in a convex spherical shape by utilizing the recessing characteristic.
Since the grinder of the second embodiment is constituted by integrally laminating the grinding layer on the surface of the low-elastic substance layer having a feature in the hardness and the hard substance layer is also integrally laminated on the back surface of the low-elastic substance layer, the end face of the ferrule can be ground in a desired convex spherical shape, the strength of the grinder can be proved by the hard substance layer to enhance the handling easiness.
Since the grinding method of the third embodiment is constituted by the steps of rotating the grinder and the ferrule when grinding the end face of the ferrule with the grinder having a predetermined elasticity, and merely pressing the end face of the ferrule to the surface of the grinder but it is not necessary to apply a special movement like rocking to the ferrule, the grinding control can be ready to obtain a desired convex sphere surface, thereby satisfying the grinding machine in a simple construction.

Claims

1. A grinder for grinding the end face of the ferrule of an optical connector in a convex spherical shape; comprising a low-elastic substance layer and a grinding layer laminated on the surface of the low-elastic substance layer formed on the grinder in such a manner that the hardness of the low-elastic substance layer is defined in a range equal to or larger than 50° of JIS-A hardness to 60° or less of Shore hardness.

2. A grinder according to claim 1, wherein said low-elastic substance layer and said grinding layer are laminated integrally through a bonding agent.

3. A grinder according to claim 1, wherein said low-elastic substance layer and said grinding layer are laminated integrally through a thermal fusion-bonding.

4. A grinder according to claim 1, wherein said low-elastic substance layer and said grinding layer are laminated integrally through a clamp.

5. A grinder for a ferrule of an optical connector according to any of claims 1 to 4, wherein said low-elastic substance layer is formed of rubber, plastic or composite material thereof.

6. A grinder for grinding the end face of the ferrule of an optical connector in a convex spherical shape; comprising a low-elastic substance layer, a grinding layer laminated integrally on the surface of the low-elastic substance layer, and a hard substance layer laminated on the back surface of the low-elastic substance layer in such a manner that the hardness of the low-elastic substance layer is defined in a range equal to or higher than 50° of JIS-A hardness to 80° or less of Shore hardness.

7. A grinder according to claim 6, wherein said low-ealstic substance layer and said grinding layer are laminated integrally through a bonding agent.

8. A grinder according to claim 6, wherein said low-elastic substance layer and said grinding layer are laminated integrally through a thermal fusion-bonding.

9. A grinder according to claim 6, wherein said low-elastic substance layer and said grinding layer are laminated integrally through a clamp.

10. A grinder for a ferrule of an optical connector according to any of claims 6 to 9, wherein said low-elastic substance layer is formed of rubber, plastic or composite material thereof.

11. A grinder according to any of claims 6 to 9, wherein said hard substance layer is formed of metal, hard rubber, hard plastic, fiber reinforced plastic, reinforced glass, ceramic or composite material thereof.

12. A method of grinding the end face of the ferrule of an optical connector in a convex spherical shape by a grinder having at least a low-elastic substance layer and a grinding layer laminated integrally on the surface of the low-elastic substance layer in such a manner that the hardness of the low-elastic substance layer is defined in a range equal to or higher than 50° of JIS-A hardness to 60° or less of Shore hardness; comprising the steps of rotating the grinder and the ferrule at the axial centers thereof as a center, and pressing the end face of the ferrule held perpendicularly to the surface of the grinder to recess the surface of the grinder, thereby grinding the end face of the ferrule in a convex spherical shape.