JPH07102499B2 - Method and device for processing spherical surface of end face of cylindrical workpiece - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber connector, a method and an apparatus for processing an end surface of a cylindrical optical material such as glass or ceramics into a convex spherical shape.

[0002]

2. Description of the Related Art FIG. 3 shows a schematic structure of a connecting portion between optical fiber connectors whose end faces are mirror-polished into a convex spherical shape. When the end faces of the optical fiber connector in which the single mode optical fiber 9 made of quartz is inserted into the glass ferrule 14 is connected to propagate an optical signal, the optical loss caused by the gap between the end faces 10 of the optical fiber is suppressed as much as possible. There is a need to. Currently, as a method for realizing a low-loss connection, the connector end face 8 is formed into a convex spherical mirror surface to form an optical fiber end face 10.
PC (Physical Control)
ACT) Polished connectors are widely used.

Generally, as shown in FIGS. 4 (a) and 4 (b), a PC-polishing connector is first processed by a grinding process using a rotary grindstone 11 or a lapping method using loose abrasive grains. The end surface 8 is formed in a conical shape. next,
The elastic sheet 13 having the fine abrasive grains 12 is attached to the connector end surface 8
The elastic sheet 13 is locally deformed and the polishing action of the fine abrasive grains 12 is applied to finish the surface into a smooth spherical surface (for example, Japanese Patent Publication No. 4-2388). This polishing process is usually performed in several steps, and the fine abrasive grains 12 to be used are successively reduced in diameter to form a desired convex spherical surface and at the same time reduce the surface roughness.

[0004]

However, the above-described spherical surface processing method has a problem that many steps are required to form the end surface of the connector into a desired spherical shape, which requires a long time. Particularly, in the polishing process for obtaining a smooth spherical surface, the elastic sheet 13 and the fine abrasive grains 12 on the sheet are used.
In order to always maintain the polishing ability of No. 1 in an appropriate state, the elastic sheet 13 and the abrasive grains 12 must be frequently replaced,
Therefore, there was a problem of low productivity.

The object of the present invention is to solve such a conventional problem, and to form not only an optical fiber connector, but also a spherical surface capable of highly efficiently forming a convex spherical surface on the end surface of a cylindrical optical material such as glass or ceramics. It is to provide a processing method and apparatus.

[0006]

According to the present invention, there is provided a spherical surface machining method for an end surface of a cylindrical work piece, which comprises rotating a cylindrical work piece in contact with a work surface of a rotary grindstone having an outer peripheral cross section formed in a concave arc shape. It is characterized in that a convex spherical surface is formed on the end surface of the workpiece by the grinding action of the concave arc-shaped work surface of the grindstone.

Further, the spherical surface machining device for the end surface of the cylindrical work piece of the present invention includes a working grindstone for working the cylindrical work piece, a correction grindstone for adjusting the shape of the working surface of the working grindstone, and the work piece. It has a mechanism for rotating the processing grindstone and the correction grindstone respectively, and arranges the working surfaces of the outer circumferences of the processing grindstone and the correction grindstone in a state where the rotation axes of both are orthogonal to each other, and brings them into contact with the working surface of the working grindstone A moving mechanism that forms a concave arc-shaped cross-sectional shape is provided, and the workpiece is arranged by matching the radial direction of the concave arc of the working surface of the working grindstone with the rotation axis of the workpiece,
It is characterized in that a moving mechanism for bringing the work surface having the concave arc shape into contact with the workpiece is provided.

[0008]

1 and 2 are a schematic perspective view illustrating a spherical surface processing method of the present invention and a plan view showing a spherical surface processing apparatus of the present invention, respectively.

The spherical surface processing method of the present invention is greatly different from the conventional method in that it is preformed on the working surface 4 by the running motion of the working surface 4 and the grinding action of the working surface 4 obtained by the rotary motion of the workpiece 1. The concave arc shape is transferred to the end surface 8 of the workpiece 1 to obtain a smooth convex spherical surface. Further, in the method of the present invention, in order to properly maintain the grinding ability of the work surface 4, increase the tool life, and reduce the frequency of exchanging the processing grindstone 2, the DC power supply 7 is used to machine the grinding grindstone 2 and the outer circumference of the grinding grindstone 2. A voltage was applied between the convex arcuate negative electrodes 6 installed in the vicinity, the weakly conductive grinding liquid 5 was supplied, and the electrolytic grinding was applied to the working grindstone 2.

By forming a concave arc shape on the work surface 4, the working grindstone 2 can be repeatedly used until the grindstone portion shown by the spots in FIG. 1 is consumed. Therefore, frequent replacement of tools such as the abrasive grains 12 and the elastic sheet 13 in the conventional method is not required, and a large number of workpieces 1 can be continuously processed.

Next, in the spherical surface processing apparatus of the present invention, the positional relationship between the processing grindstone 2 and the correction grindstone 3 is such that the rotation axes of the two are orthogonal and the running directions of the outer peripheral work surfaces of both grindstones are orthogonal. By making the working grindstone 2 and the correction grindstone 3 contact with each other while maintaining this positional relationship, a concave arc-shaped cross-sectional shape is formed on the work surface 4 of the working grindstone 2. The radius of curvature of the concave arc of the work surface 4 was set to a required value by changing the radius of the correction grindstone 3.

After forming the concave arc shape on the work surface 4, the positional relationship is maintained such that the radial direction of the concave arc and the rotation axis of the work piece 1 are matched with each other, and the work surface 1 and the work piece 1 rotating are rotated. Contacted. If the grinding ability of the work surface 4 is properly maintained, a convex spherical surface having a radius of curvature of the concave arc of the work surface 4 and thus a radius of curvature equal to the radius of the correction grindstone 3 is formed on the end surface 8 of the work piece 1. Was done. Furthermore, when the shape of the work surface 4 is deformed by the progress of the grinding process and the good convex spherical end face 8 cannot be obtained, the work grindstone 2 and the correction grindstone 3 are again brought into contact with each other, whereby the work surface 4 Could be easily corrected to the exact concave arc shape.

In the spherical surface processing apparatus of the present invention, the work surface 4
In order to properly maintain the grinding ability of the machine and increase the tool life to reduce the frequency of exchanging the processing wheel 2, the processing wheel 2 of metal bond and the correction wheel 3 having a low degree of bonding such as resin bond
Was used. Then, a voltage is applied from the DC power supply 7 between the working grindstone 2 and the negative electrode 6 having a convex arc shape installed in the vicinity of the outer circumference of the working grindstone 2 to supply the weakly conductive grinding fluid 5 to the working grindstone 2. An electrolytic dressing was applied.

Further, excessive electrolytic dressing rapidly elutes and removes the bonding material of the metal-bonded grindstone 2, depleting the grindstone 2 and destroying the concave arc shape of the work surface 4. The electrolytic dressing action was added only when the end surface 8 of was processed into a convex spherical surface. When the work surface 4 was modified to have a concave arc-shaped cross section, the addition of electrolytic dressing was stopped. By repeating this cycle to process the work piece 1, the shape of the work surface 4 is deformed due to excessive addition of electrolytic dressing, the wear of the processing grindstone 2 is rapidly reduced, and the shape of the work surface 4 is corrected. Excessive wear of the processing grindstone 2 could be suppressed, and the end surface 8 could be processed into a convex spherical surface having a small surface roughness.

In the spherical surface processing apparatus of the present invention, when the end surface 8 is brought into contact with the concave arc-shaped work surface 4 to form a convex spherical surface, the work 1 is made into a constant cut while being brought into contact with the work surface 4. 20 and a constant pressure mechanism 21 for bringing the workpiece 1 into contact with the work surface 4 while applying constant pressure. The work grindstone 2 and the work piece 1 are constantly subjected to rotational runout and vibration, so that the convex spherical shape of the end face 8 is distorted or uneven. The present invention has an effect of suppressing the above-mentioned distortion and unevenness.

That is, the spherical surface processing apparatus of the present invention transfers the concave arc shape formed on the work surface 4 to the end surface 8 of the workpiece 1 to obtain a convex spherical surface. Normally, the work piece 1 has a processing stone 2
Grinding is often performed while giving a constant cut in the radial direction, and therefore, if the grinding wheel 2 or the workpiece 1 has rotational runout or vibration, intermittent grinding is performed and the spherical surface 8 has a convex spherical shape. There will be distortion and unevenness. However, in the grinding in the constant pressure state, the step of firstly roughening the end face 8 by making a constant cut with the workpiece 1 and then contacting with the constant pressure to finish the convex spherical surface is performed. Rotational shake and vibration were absorbed and suppressed. As a result, intermittent grinding can be prevented and a smooth convex spherical surface can be formed on the end face 8.

Next, examples of the present invention will be described, including specific processing conditions. Bronze bond and mesh 4000 diamond abrasive grains are used for the processing grindstone 1, and the outer diameter is 75
mm and the thickness was 5 mm. The modified grindstone 3 is a resin bond, and a diamond abrasive grain of mesh 3000 is used for the outer shape 4
The one having a thickness of 0 mm and a thickness of 5 mm was used. As the columnar workpiece 1, an optical fiber connector in which a quartz single mode optical fiber 9 was inserted into a glass ferrule 14 as shown in FIG. 3 was used.

First, the rotation speed of the processing grindstone 2 is set to 2000 rp.
m, the rotary motor 19 of the correction grindstone 3 is rotated at 100 rpm, the stage 15 is moved to bring the correction grindstone 3 closer to the direction of the processing grindstone 2, and both are brought into contact with each other while supplying the grinding fluid 5 to work the processing grindstone 2. A concave arc surface having a radius of curvature of 20 mm was formed on the surface 4. The concave arc shape of the work surface 4 is the grinding wheel 2
A bond having a radius of curvature equal to that of the correction grindstone 3 was formed without being affected by the bond material and the abrasive grains of the correction grindstone 3.

Next, while supplying the grinding liquid 5 between the negative electrode 6 and the working grindstone 2, a DC voltage was applied from the power supply 7 during this period, and the work surface 4 was subjected to electrolytic dressing.
In this embodiment, immediately before performing the convex spherical surface machining of the end surface 8 of the workpiece 1, electrolytic dressing with an electrolytic current value of 2 A for 15 seconds is added to project abrasive grains distributed on the surface of the work surface 4,
The grinding ability of the work surface 4 was in a good state.

Then, while the workpiece 1 is being rotated, it is brought into contact with the processing grindstone 2 at a constant speed by a constant cutting mechanism 20 using a pulse stage to make rough contact, and then,
The workpiece 1 was brought into contact with each other for 5 seconds while applying a load of 500 g to the workpiece 1 by the constant pressure mechanism 21 using an air cylinder. The addition of this constant load was effective in removing the abrasive grains particularly protruding from the work surface 4 to evenly align the protrusion of the abrasive grains on the surface of the work surface 4 and suppress the scratches generated on the end surface 8. . The workpiece was rotated at 50 rpm by the reversing motor 18 and processed while being reversed every 1.5 rotations. Finally, the constant pressure mechanism 21 was used to apply a low load of 100 g to the work piece 1 to bring it into contact with the work surface 4 for another 10 seconds to finish the end surface 8 of the work piece 1.

The radius of curvature of the spherical surface formed on the end face 8 is equal to the radius of curvature of the concave arc of the working surface 4 of the working grindstone 2 and is 20 mm.
Thus, a smooth convex spherical surface having a surface roughness of 0.08 μmRmax or less and having no distortion was obtained. In the present embodiment, the work piece 1 used the optical connector made of glass, but the same good convex spherical surface was obtained even if the optical connector made of the zirconia ceramics as the ferrule 14 shown in FIG. 4 was used. .

When the end surface 8 of the workpiece 1 is ground without adding electrolytic dressing to the working grindstone 2, the grinding ability of the working surface 4 of the working grindstone 2 cannot be properly maintained, and the end surface 8 is a surface. The surface became a satin finish with a roughness of 0.2 μm Rmax or more. Further, even if electrolytic dressing is added, when the workpiece 1 and the work surface 4 are brought into contact with each other only by giving a certain depth of cut, intermittent grinding occurs due to rotational runout of the processing grindstone 2 and the end surface 8 has a convex spherical shape. Distortion or unevenness occurred.

Next, in order to re-correct the concave arc shape of the work surface 4 which has collapsed due to the processing of the end surface 8, the addition of electrolytic dressing is temporarily stopped and the stage 15 is moved to bring the correction grindstone 3 into contact with the working grindstone 2. Let By this correction work, the outer diameter of the grindstone 2 was decreased by 3 μm. However, processing grindstone 2
When the end surface 8 was processed without adding any electrolytic dressing to the work surface 4, the work surface 4 was excessively ground and the concave arc shape was largely destroyed. Further, when the shape of the work surface 4 was also corrected while the electrolytic dressing was added, the metal bond material of the processing grindstone 2 was excessively removed. Therefore, the outer diameter of the grindstone 2 was reduced from 5 μm to 8 μm for each shape modification.

After modifying the working surface 4 to have a precise concave arc-shaped cross-sectional shape, the electrolytic dressing action is added again,
The end surface 8 of the second workpiece 1 was ground into a convex spherical surface.
When the processing cycle shown in the above example was repeated and the workpiece 1 was continuously processed until the grindstone portion of the processing grindstone 2 was consumed, the radius of curvature was 20 mm and the surface roughness was 0.08 μmRm.
A smooth convex spherical surface of ax or less could be obtained with high reproducibility for 1000 workpieces.

The spherical surface processing time per optical fiber connector in this embodiment was reduced to 1/2 or less as compared with the time required to obtain a similar spherical surface quality using the conventional method. Also, the loss time required to replace tools is 1 /
It could be reduced to 50 or less.

[0026]

As described above, according to the present invention, the end surface of the columnar material such as the optical fiber connector made of glass, ceramics or the like can be processed into a convex spherical surface in a shorter time than the conventional method. Also, the frequency of exchanging machining tools can be greatly reduced, and the productivity of spherical machining can be greatly improved.

[Brief description of drawings]

FIG. 1 shows a perspective view illustrating a spherical surface processing method of the present invention and a plan view showing a spherical surface processing apparatus of the present invention.

FIG. 2 shows a perspective view illustrating a spherical surface processing method of the present invention and a plan view showing a spherical surface processing apparatus of the present invention.

FIG. 3 is a diagram showing a schematic configuration of an optical fiber connector.

FIG. 4 is a plan view showing a conventional spherical surface processing method.

[Explanation of symbols]

 1 Workpiece 2 Processing grindstone 3 Correcting grindstone 4 Working surface 5 Grinding liquid 6 Electrode 7 Power supply 8 End face 9 Optical fiber 10 Fiber end face 11 Rotating grindstone 12 Abrasive grains 13 Elastic sheet 14 Ferrule 15 Stage 16 Machining part cover 17 Chuck 18 Inversion motor 19 rotary motor 20 constant cutting mechanism 21 constant pressure mechanism

Claims (4)

[Claims] Claim: What is claimed is: 1. An end surface of a work piece is brought into contact with a work piece of a cylindrical grindstone whose outer peripheral cross section is formed into a concave arc shape by contact-rotating a work piece having a cylindrical shape with a grinding action of the work surface of the grindstone with the concave arc shape. A method for processing a spherical surface of an end surface of a cylindrical workpiece, characterized in that a convex spherical surface is formed on the surface. 2. A processing grindstone for processing a cylindrical workpiece,
There is a correction grindstone that adjusts the shape of the working surface of this processing grindstone, and a mechanism that rotates the workpiece, the processing grindstone, and the correction grindstone, respectively. A moving mechanism for forming a concave arc-shaped cross-sectional shape on the working surface of the working grindstone by placing them in contact with each other, and the radial direction of the concave arc of the working surface of the working grindstone and the workpiece. A spherical surface machining device for an end surface of a cylindrical work piece, wherein a work piece is arranged with the rotation axes aligned with each other, and a moving mechanism for bringing the work surface having the concave arc shape into contact with the work piece is provided. 3. The working grindstone is a metal bond grindstone, the correction grindstone is a grindstone with a low degree of bonding, and a convex arcuate electrode for adding an electrolytic dressing action is provided on the concave arcuate work surface of the working grindstone. The spherical surface processing apparatus for an end face of a cylindrical workpiece according to claim 2. 4. A constant cutting mechanism for bringing the workpiece into contact with a concave arcuate work surface of the machining grindstone while making a constant cut, and a concave arcuate work surface of the machining grindstone while applying a constant pressure. 4. A spherical surface machining device for an end surface of a cylindrical work piece according to claim 2, further comprising a constant pressure mechanism for contacting the work piece.