JPS5969258A - Polishing method of glass rod - Google Patents

Abstract

PURPOSE:To polish the glass rod surface into an optical column smooth face by clamping a glass rod of an optical fiber base material at both ends with rotary chucks and reciprocating an abrasion plate fitted with the abrasion paper, burnishing cloth, etc. for abrasion. CONSTITUTION:Both ends of a glass rod 21 to be machined are clamped by rotary chucks 3, 8. At the same time, a limiter switch 24 is set in such a position that it can be operated by an abrasion plate support bed 20 when the end of an abrasion plate 19 reaches a position very near the rotary chuck 8. Then, a chuck rotating motor 10 is rotated to rotate the glass rod 21 and also rotate an abrasion plate support bed moving motor 22, and the abrasion plate 21 is repeatedly reciprocated against the glass rod 21 along its whole length, thus the rod 21 is polished by the abrasion paper stuck to the abrasion plate 19. Finally, the burnishing cloth is stuck to the abrasion plate and the suspension of fine abrasion grains is fed through a liquid feed hose 25, then the glass rod 21 can be finished into an optical column smooth face.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for polishing a cylindrical glass rod, such as a preform for an optical fiber, to an optically smooth surface.

When manufacturing an optical fiber by drawing a cylindrical glass rod base material in a highly viscous state, the surface of the cylindrical glass rod base material must have an optically cylindrical smooth surface or the optical fiber will not be drawn. The surface may become uneven or the cross section may not be perfectly round. Therefore, it is necessary to make the surface of such a cylindrical glass rod an optically cylindrical smooth surface9.Therefore, as a conventional method to make such a cylindrical glass rod an optically cylindrical smooth surface, the glass rod is mounted on a rotating chuck. It was common practice to rotate the material while supporting it, cut it with a diamond tool, etc., and then polish it with abrasive grains, or simply melt the surface with flame to make it smooth.

Although this method can be applied to hard and strong glasses such as quartz glass, it is difficult to use a diamond bite for glass rods with low hardness and strength such as optical glass, fluoride glass, and chalcogenide glass. There are disadvantages in that deep cutting marks are formed and breakage occurs, and the polishing efficiency is poor, while flame-based methods tend to melt too much and become uneven, making it difficult to apply.

The present invention provides a method for polishing a glass rod, which enables even a lot of glass with low hardness and moderate strength to be polished into an optical cylindrical smooth surface efficiently and without fear of breakage. , the drawings will be explained in detail below.

FIG. 1 shows a configuration diagram of the polishing apparatus used in the present invention, in which 1 is a base, 2 is a rotary chuck fixed support stand erected on the base 1, and 3 is a rotating chuck supported by the rotary chuck fixed support stand 2. The chuck 4 is a rotary chuck movable support stand, which is supported by the base 1 and moves left and right while being guided by a rail 7 by the rotation of a feed screw rod 6 to which a handle 5 is fixed. 8 is a rotary chuck supported by a movable support base 4; 9 is a rotary chuck drive rotary belt; the other side thereof is hung on a rotary shaft 11 rotated by a chuck rotation motor 10. The rotating shaft 11 is provided with circumferential irregularities in the axial direction,
The inner surface of the belt 9 has projections and depressions that mesh with the projections and depressions of the rotating shaft 11. Reference numeral 112 denotes an abrasive plate support stand, and as shown in FIG.
An insertion hole 16 is provided, and two polishing plate holding pieces 17 are provided protruding from the upper part. 18 is a screw whose tip is inserted into a hole in the polishing plate holding piece 17 and screwed into a screw hole in the polishing plate 19;
A spring 20 is inserted into a screw 17 between the abrasive plate holding piece 16 and the abrasive plate 18, and elastically presses the abrasive plate 2o against a glass rod 21 whose both ends are held by a rotary chuck 3.8. Do it like this. 22 is a motor for rotating the screw rod and moving the polishing plate support 12, and a limiter switch 23 which is switched by the polishing plate support 12.
24, so that the polishing plate support base 12 is reciprocated. The limiter switches 23 and 24 are arranged at positions such that when the polishing plate 19 comes close to the rotary chucks 3 and 8, the motor 22 is actuated to reverse the direction of movement of the polishing plate support 12. The limiter switch 24 on the rotary chuck movable support base 4 side can be moved to match the length of the glass rod 21 since the rotary chuck 8 also moves when the movable support base 4 is moved to match the length of the glass rod 21. There is. 25 is a liquid feeding hose for feeding water or abrasive grain turbid liquid to the surface of the glass rod 21; 26 is a waste liquid receiver, which is placed on the waste liquid receiver support 27; The waste liquid that falls inside is directed to the outside.

The present invention uses the apparatus described above, and first, both ends of the glass rod 21 to be processed are held between the rotary chucks 3 and 8. At this time, the rotary chuck movable support base 4 is moved by turning the handle 5 according to the length of the glass rod 2, so that the glass rod 21 at that time can be clamped. At the same time, the limiter switch 24 is set at such a position that it can be operated by the polishing plate support 20 when the end of the polishing plate 19 comes very close to the rotary chuck 8. Further, waterproof abrasive paper is pasted on the abrasive plate 19. Therefore, when the chuck rotation motor 1° is turned to rotate the glass rod and the abrasive plate support table moving motor 22 is also rotated, the abrasive plate 19 is moved from the glass rod 21 to the point where the glass condo 210 is attached to the rotating chuck 3. 8. The abrasive paper attached to the abrasive plate 19 repeats reciprocating motion over the entire length up to the attachment point. At this time, water is sent from the liquid feeding hose to cool the glass rod 21 and wash away the polishing debris.

If the abrasive paper wears out before it has been sufficiently polished, it can be replaced with a new one.

If the initially used abrasive paper is too rough, polish in the same manner using abrasive papers with progressively finer grains.

Because the abrasive paper attached to the abrasive plate is used to polish the rod, even if it is a small glass rod with low hardness and strength, a wide area is polished at the same time without creating deep cutting marks, so there is no risk of breakage and the entire length is polished. . Finally, the polishing plate 19
A polishing cloth is attached to the abrasive cloth, and a lNj slurry of extremely fine abrasive grains is fed from the liquid feeding hose 25. The abrasive grains enter between the polishing cloth and the surface of the glass rod 21, and the polishing plate 19
By the reciprocating motion of the glass rod 21, the glass rod 21 is finely polished mainly by abrasive grains, and is finished into an optically cylindrical smooth surface.

In addition, various types of abrasive paper and polishing cloth can be replaced on one abrasive plate 19. Of course, it is also possible to prepare abrasive plates covered with various types of abrasive paper and polishing cloth, and replace the abrasive plates as needed.

To describe one example of polishing according to the method of the present invention, 30.4BaF
2-3.7GaF3-58. I ZrF4-3.8At
Core composition of F5-4SbF3 (?1to7%) and 29
．． 8F3aF2-3.6GaFs-56,92rF4-
A 9nx120mm fluoride cylindrical glass iron made of cladding of 5.7A/Fz-4SbF3 (ηto1%) was mounted on the apparatus shown in Figure 1, and while rotating at 36rpm using a rotary chuck, it was first heated to 400° water resistant. Abrasive paper was pasted on the polishing plate, the polishing plate support was moved at a speed of 5 mm/distance, and rough polishing was carried out while sending water from the liquid supply hose at 100 σ/distance. Next, number 600, 100
Polishing was carried out in the same manner using No. 0 and No. 1500 abrasive papers. Finally, the polishing cloth is pasted on the polishing plate, and the particle size is 0.0.
A solution in which 6 μm alumina abrasive grains were suspended was dropped from a water supply hose at a rate of 10 Hiroshi/Il + 1 #, and the material was polished for 2 hours under the same conditions as above. A glass rod matrix with an optically uniform surface could be obtained. Ta.

The glass rond base material whose surface has been made optically uniform in this way is coated with Teflon FEP and drawn at 3600C to achieve a relative refractive index difference of 0.2%, a core diameter of 34 μm, a cladding diameter of 150 μm, and a transmission loss of 2.557'. at, 12dB/K
A fluoride optical fiber of m was obtained.

Although the above description has been about glass iron polishing for optical fibers, it can also be used for polishing glass laser rods and the like.

According to the method of the present invention, as described above, since the polishing is first carried out using the abrasive paper attached to the abrasive plate, there is no fear of breakage even in the case of glass iron having low hardness and strength. Finally, since polishing is performed using a polishing cloth and an abrasive suspension of ultrafine particles, the glass rond surface can be polished to an optically cylindrical smooth surface. In addition, since the abrasive plate covered with abrasive paper or polishing cloth is reciprocated in the longitudinal direction of the glass rond to polish a wide area at the same time, it is possible to efficiently polish optical surfaces, including the case of hard glass ronds made of quartz glass, etc. Can be polished.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a glass rond polishing apparatus used in the method of the present invention, and FIG. 2 is an enlarged view of the polishing plate support portion of the same apparatus. 3.8... Rotating chuck, 10... Chuck rotation motor, 12... Polishing plate support base, 19... Polishing plate, 2
1...Glass iron, 22...Motor for moving the polishing plate support, 23.24...Remix switch, 25...
・Liquid transfer hose patent applicant Nippon Telegraph and Telephone Corporation

Claims (1)

[Claims] The glass rod is gripped by a rotary chuck at both ends and rotated, while the abrasive plate with abrasive paper attached is repeatedly moved back and forth in the longitudinal direction of the glass rod to polish it.Finally, a polishing cloth is attached. A method for polishing a glass rod, comprising repeatedly reciprocating a polishing plate, and simultaneously supplying an abrasive suspension of ultrafine particles to the surface of the glass rod according to the reciprocating polishing plate.