JP2003062743A - Spherical grinding device and spherical grinding method for ferrule - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device relating to machining technique for the top of a ferrule used for a connection of optical fibers, which permit spherical grinding with accuracy, steadily and efficiently. SOLUTION: A ferrule 8 is driven to rotate around the work axis, and the top of the ferrule 8 is ground spherically by the rim 24 of a cup wheel 15 at the top of the wheel spindle 9 which is supported with a tilting frame. The tilting frame is tilted around the tilting axis which is perpendicular to the work axis. A truing tool is attached to the tilting frame, and the outside angle of the cup wheel rim is trued slantwise preferably at angle 45 degree or less, so that the grinding face T of the cup wheel rim is kept in 0.5 to 0.8 mm for grinding the work. The truing motion is performed when a sensor detects a wear of the wheel rim. Because the face which does not contact with the work is trued to modify, dressing for the trued surface becomes unnecessary.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for performing spherical surface processing on the tip of a ferrule used in a connecting portion of an optical fiber.

[0002]

2. Description of the Related Art The diameter of a standard optical fiber used in an optical cable for information communication is about 125 μ, and a component called a ferrule is used at its connection end. Since the information is transmitted by the laser light passing through the core glass while totally reflecting the optical fiber, the connecting ends of the two optical fibers are simply butt-connected so that the light passes from one to the other. do it. However, since the optical fiber is very thin, and the connection loss at the connection portion and the reflection at the incident surface cause a ghost, the connection end is processed into a highly accurate spherical surface.

The above-mentioned ferrule used for connecting the optical fiber is a ceramic cylindrical member having a hole for inserting the optical fiber at the center, and its outer diameter is usually 2.5.
mm or 1.25 mm. The connecting end of the optical fiber is
The tip of the ferrule is processed so as to follow the tip surface of the ferrule after being inserted into the center hole of the ferrule having a spherical tip, so that it becomes necessary to process the tip of the ferrule into a highly accurate spherical surface. The spherical processing of the tip of the ferrule can be performed by using a cup-shaped grindstone in the same manner as the spherical processing of the lens.
The principle of this spherical surface processing method can be easily understood by assuming a state in which a cup (bowl) is placed obliquely on a spherical surface. The spherical surface to be machined is rotated around the machining center axis, and the cup-shaped grindstone that is obliquely in contact with the top is rotated around the center axis at high speed. The work is ground along the peripheral edge of the cup-shaped grindstone, and the grinding locus on the spherical surface has a twill shape.

There are two major differences between the spherical processing of the lens and the spherical processing of the tip of the ferrule. First, in lens processing, after performing spherical surface creation with a cup-shaped grindstone,
Since polishing work such as lapping is performed on the spherical plate, the influence of the wear of the cup grindstone on the spherical accuracy is small. Furthermore, a hard grindstone using an electrodeposition grindstone or a metal bond can be used as the grindstone. Therefore, wear of the grindstone is relatively small, and it is not necessary to frequently shape the grindstone. On the other hand, in the processing of the ferrule, since the grinding process with the cup-shaped grindstone is the final processing, the wear of the cup-shaped grindstone directly affects the spherical surface accuracy. In addition, in order to obtain high surface accuracy, a grindstone using resin bond and having relatively large wear is used. Therefore, frequent grinding and dressing of the grindstone are required to obtain an accurate processed shape.

The second difference is that the ferrule is much smaller than the lens. Ferrule diameter is approximately 2.
The diameter of the cup-shaped grindstone is 5 to 15 mm, while it is 5 mm or 1.25 mm. Moreover, the thickness of the peripheral edge of the cup-shaped grindstone using the resin bond is 2 due to the strength limitation.
There is about mm. Therefore, in the spherical processing of the lens, the peripheral edge of the cup-shaped grindstone is on the spherical surface to be processed, but in the grinding of the ferrule,
The tip of the ferrule is in contact with one point on the periphery of the cup-shaped grindstone. Therefore, the shape of the grinding surface of the cup-shaped grindstone greatly affects the processing accuracy, and frequent grinding and dressing of the grindstone are required.

A cup-shaped grindstone using a resin bond as a binder needs to have a grindstone thickness of about 2 mm at its peripheral edge. Therefore, in order to realize the line contact between the peripheral edge of the cup-shaped grindstone and the processed surface, the peripheral edge of the grindstone is conventionally shaped into a semicircle as shown in FIG.

[0007]

As described above, in the spherical grinding of the ferrule, the abrasion of the grindstone is large, and the peripheral edge of the grindstone needs to be shaped and dressed frequently, but the ferrule has a small surface to be machined. Since the machining time is short and the abrasion of the grindstone follows the spherical surface of the surface to be machined, the accuracy of the machined surface due to the abrasion of the grindstone is relatively moderate. Therefore, in an actual machining site, time-consuming shaping and dressing of the grindstone is omitted as much as possible, and in an extreme case, as shown in FIG. Since the grinding stone is used for processing, the deterioration of the processing accuracy due to the abrasion of the grinding stone poses a problem.

Therefore, an object of the present invention is to provide a spherical surface processing method and device for a ferrule tip which can efficiently perform spherical surface processing of a ferrule tip with high accuracy without variations in processing accuracy.

[0009]

SUMMARY OF THE INVENTION A spherical grinding apparatus of the present invention comprises a work shaft 25 for rotating a substantially cylindrical work (ferrule) 8 about its axis and a tilt shaft 6 orthogonal to the work shaft. A tilting frame 5 that tilts and a grindstone shaft 9 that drives the cup-shaped grindstone 15 to rotate about an axis that is orthogonal to the tilting axis and intersects with the work axis are provided. The tip of the work 8 is spherically processed by the peripheral edge 24 of the cup-shaped grindstone.

The spherical grinding apparatus of the present invention is provided with a grindstone shaping tool 21 on the tilting frame 5, and the grindstone is shaped by removing the outer corner of the peripheral edge of the cup-shaped grindstone with this shaping tool. To do.

A preferable shaping is performed by removing the outer edge of the peripheral edge of the cup-shaped grindstone 15 obliquely with a shaping tool 21 at an angle smaller than 45 degrees.

In the spherical surface grinding method of the ferrule of the present invention, the spherical surface grinding device equipped with the above means is used, and the grinding surface width T of the peripheral edge of the cup-shaped grindstone mounted on the grindstone shaft is 1 mm or less, preferably 0 by the shaping tool. The workpiece is machined while maintaining a constant width set to 0.5 to 0.8 mm or less.

More preferably, as the cup-shaped grindstone, a grindstone in which diamond abrasive grains are bonded by vitrified bond is used.

Separation devices 16 and 18 for separating the work shaft 25 and the grindstone shaft 9 when the work shaft 25 is loaded or unloaded,
By using a spherical grinding device equipped with a wear detection sensor 20 for detecting the wear amount of the grindstone periphery, the grinding tool peripheral edge removal by the shaping tool 21 at the time of mounting and dismounting of the workpiece is performed on condition that the sensor 20 detects the wear of the grindstone periphery. It is possible to perform a shaping operation with a constant algebra.

The above-described feature of the spherical surface processing method of the ferrule tip of the present invention is that the outer edge of the peripheral edge of the grindstone is removed by the shaping tool 21 so that the grinding surface width T of the peripheral edge of the grindstone that is substantially in contact with the surface to be processed is T. By making the width as small as possible and removing the surface that does not contact the work, the grinding stone peripheral edge is shaped, so dressing of the shaped surface becomes unnecessary,
Therefore, the dressing time can be saved.

By removing the outer edge of the grindstone edge by 45 degrees or less, preferably by making it as small as possible, the grinding surface width T can be reduced as much as possible without reducing the strength of the outer edge of the grindstone. It becomes possible to make it small. The grinding surface 24a formed on the inner side of the periphery of the grindstone comes into surface contact with the surface to be processed, and by setting this to a width of 1 mm or less, preferably about 0.5 to 0.8 mm or less, The required spherical accuracy of the ferrule tip can be realized.

If a grindstone using vitrified bond as a binder is used, the strength of the grindstone can be increased as compared with the resin bond, so that the grinding surface width T at the periphery of the grindstone can be made smaller. . Further, as a result, the thickness of the peripheral edge of the grindstone can be reduced to about 1.2 mm, so that the removal amount of the grindstone at the time of shaping the grindstone becomes small and the shaping time can be shortened.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the examples shown in the drawings. 3 and 4 are diagrams schematically showing the entire structure of the spherical surface processing apparatus, FIG. 3 is a side view, and FIG. 4 is a front view. A spindle case 2 is fixed in the vertical direction to a frame 1 of which only the upper end is shown.
A vertical work shaft 25 having the work chuck 3 mounted on the upper end thereof is rotatably supported and is rotationally driven by a motor (not shown) incorporated in the frame.

A case 4 of the tilting device is fixed on the frame 1. In the case 4, tilting frame 5 to FIG.
A tilting shaft 6 extending leftward is pivotally supported, and a handle 7 for turning the tilting frame 5 around the tilting shaft 6 by a desired angle by rotating a worm that meshes with a worm wheel fixed to this tilting shaft. Is provided. Tilt axis 6
And the work shaft 25 intersect at a right angle in the same plane. Although not shown in detail in the drawing, the tilt frame 5 is provided in the case 4.
It has a built-in guide device and lock device to achieve high position accuracy. The tilt axis 6 is exactly aligned with the tip of the ferrule 8 held by the work chuck 3.

The tilting frame 5 is a plate-like member having a home-base shape when viewed from the front, and a tilting shaft 6 is fixed to the lower part thereof. A grindstone shaft 9 to be described later is provided on the upper portion of the tilting frame 5.
An X-axis guide 10 is provided in a direction orthogonal to the X-axis guide 10, and an X-axis slide 11 is movably mounted along the X-axis guide. The X-axis slide 11 is provided with a Z-axis guide 12 in a direction parallel to the grindstone shaft 9, and the Z-axis slide 13 sliding along the Z-axis guide is equipped with the grindstone shaft 9 and the grindstone shaft drive motor 14. There is. Grindstone axis 9 axis and work axis 2
The axis of 5 is on a plane orthogonal to the tilt axis 6. A cup-shaped grindstone 15 is attached to the lower end of the grindstone shaft 9. X
The shaft slide 11 is screwed into an X-axis ball screw 17 that is driven in the reverse direction by an X-axis servomotor 16, and the Z-axis slide 1
The reference numeral 3 is screwed onto a Z-axis ball screw 19 which is driven in the reverse direction by a Z-axis servomotor 18. Therefore, the NC device controls the X-axis servomotor 16 and the Z-axis servomotor 18 to move and set the position of the cup-shaped grindstone 15. Since the X-axis guide 10 is fixed to the tilting frame 5, by tilting the tilting frame 5, X
The axial direction and the Z-axis direction are also inclined.

A photoelectric sensor 20 and a shaping grindstone 21 are mounted on the lower left portion of the tilting frame 5 in FIG. The photoelectric sensor 20 is a transmission type sensor including a light transmitter and a light receiver which are arranged at intervals in the direction perpendicular to the paper surface of FIG. 4, and detects the tip of the cup-shaped grindstone 15. The shaping grindstone 21 is a short cylindrical grindstone having an outer peripheral surface as a grinding surface, and is rotationally driven by a shaping motor 22.
Is inclined about 30 degrees with respect to the X-axis and is positioned in a plane orthogonal to the tilt axis 6 including the center of the grindstone axis 9.

The cup-shaped grindstone 15 is, as shown in FIG.
In a state in which the tilting frame 5 is tilted by the tilt angle θ, the peripheral edge 24 of the tilting frame 5 contacts the tip of the ferrule 8 held by the work chuck 3 to perform spherical processing of the ferrule tip. The peripheral edge 24 of the grindstone is a grinding surface 24a that contacts the tip of the ferrule,
The outer shaping surface 24b is provided, and the shaping surface 24b
Is formed by obliquely cutting the outer corner of the peripheral edge of the cup-shaped grindstone on the outer periphery of the shaping grindstone 21 shown by an imaginary line in FIG. 1, and the inner part that is not cut is the grinding surface 24a having the width T. The width of the grinding surface 24a is about 0.5 to 0..0 when a grindstone bonded by vitrified bond is used.
It is 8 mm.

The shaping grindstone 21 shapes the grindstone periphery at a necessary timing so that the width T of the grinding surface is maintained at a predetermined width. Specifically, when the work (ferrule) 8 held by the work chuck 3 is replaced, when the Z-axis slide 13 is retracted, the X-axis slide 11 is simultaneously moved to the left in FIG. The Z-axis slide is moved slightly forward, and from the advanced position counted by the NC device and the detection position of the grindstone tip by the photoelectric sensor 20, the grinding surface 24 is detected.
When the wear of the grindstone is detected by detecting the wear amount of a, the Z-axis slide 13 is further advanced to bring the peripheral edge of the grindstone into contact with the shaping grindstone 21, thereby cutting the shaping surface 24b and performing grinding. The width T of the surface 24a is kept constant.

The processing cycle of the ferrule 8 is 15
It takes about a second, and a pallet with a large number of ferrules is placed on the right side of the work chuck 3 in Fig. 3, and two workpieces are provided on the tip of the robot arm for loading and unloading. The operation of transporting the work to the work chuck 3 and the processed work 3
The work is attached and detached by performing one reciprocating motion of the arm, which is removed from the pallet and set in the pallet. The shaping of the cup-shaped grindstone described above is performed during the work exchanging operation of the robot arm.

In a cup-shaped grindstone using vitrified bond as a binder, the thickness W of the peripheral edge of the grindstone is 1.2 mm.
It can be made as thin as possible. By reducing the angle of the shaping surface 24b with respect to the grinding surface 24a, the width T of the grinding surface can be sufficiently reduced without reducing the strength of the grinding wheel peripheral edge due to the removal of the outer corner portion of the grinding wheel peripheral edge. With this, it is possible to realize accurate spherical surface machining based on the principle of spherical surface generation (curve generation) by a cup-shaped grindstone.

Further, since the shaping surface 24b is a surface that does not contact the tip of the ferrule, that is, a surface that does not contribute to processing, it is not necessary to perform dressing (dressing), and since only the shaping operation is required, the dressing step is unnecessary, The cup-shaped grindstone can be shaped in a short time, and by performing this shaping operation when exchanging the work, it is possible to prevent the productivity from being reduced due to the shaping of the grindstone. In terms of shapeability, it is advantageous to use an aerated hole type (bond bridge type) grindstone. Therefore, a diamond bridge is used as the cup-shaped grindstone and a vitrified bond is used as the bond bridge bond type. Most preferably, the whetstone of

[Brief description of drawings]

FIG. 1 is a sectional side view showing the relationship between a ferrule tip and a cup-shaped grindstone during grinding.

FIG. 2 is an explanatory view showing movement of a cup-shaped grindstone between a processing position and a shaping position.

FIG. 3 is a side view showing a main part of a spherical surface processing device.

4 is a front view of the device of FIG.

FIG. 5 is a cross-sectional side view showing the relationship between the cup-shaped grindstone whose peripheral edge is shaped into a semicircular section and the ferrule tip.

FIG. 6 is a view similar to FIG. 5 showing a work grinding state in which the cup-shaped grindstone of FIG. 5 is worn.

[Explanation of symbols]

5 Tilt frame 6 Tilt axis 8 ferrules 9 Wheel axis 15 cup-shaped grindstone 16 X-axis servo motor 18 Z-axis servo motor 20 Photoelectric sensor 21 shaping wheel 24 rim 25 work axis T grinding surface width

Claims (6)

[Claims] 1. A work shaft (25) for rotationally driving a substantially cylindrical work (8) about its axis, and a tilting frame (5) tilting about a tilting shaft (6) orthogonal to the work shaft, And a grindstone shaft (9) for driving the cup-shaped grindstone (15) to rotate about an axis orthogonal to the tilt axis and intersecting with the work axis, and the peripheral edge of the cup-shaped grindstone attached to the tip of this grindstone shaft ( In the spherical grinding device of the ferrule that spherically processes the tip of the work (8) in 24), a grinding stone shaping tool (21) is provided on the tilting frame, and the shaping tool removes the outer corner of the peripheral edge of the cup-shaped grinding stone. A spherical surface grinding device for a ferrule that shapes the whetstone by doing the above. 2. The spherical grinding device according to claim 1, wherein the grindstone shaping tool (21) shapes the grindstone by obliquely removing the outer edge of the peripheral edge of the cup-shaped grindstone at an angle smaller than 45 degrees. 3. A grinding surface width of a peripheral edge of a cup-shaped grindstone mounted on a grindstone shaft by using the spherical grinding apparatus according to claim 1 or 2.
A method of spherically grinding a ferrule, which comprises shaping a workpiece by shaping with a shaping tool such that (T) is maintained at a constant width of 1 mm or less. 4. The spherical grinding method according to claim 3, wherein a cup-shaped grindstone in which diamond abrasive grains are bonded with a vitrified bond is used. 5. A contact / separation device (16, 18) for separating the work shaft (25) from the grindstone shaft (9) when the work shaft is attached to and detached from the work shaft (25), and the amount of wear of the grindstone periphery. The spherical grinding device according to claim 1 or 2, further comprising a wear detection sensor (20) for detecting the. 6. The spherical grinding apparatus according to claim 5, wherein the shaping tool (21) removes the peripheral edge of the grindstone when the workpiece is loaded / unloaded on condition that the sensor (20) detects wear of the peripheral edge of the grindstone. 5. The spherical grinding method according to claim 3, wherein the shaping operation is performed with a constant value.