JPS5945612B2 - Support method for rod for optical transmission line spinning - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for supporting a preform rod of an optical transmission line;
In particular, the present invention relates to a method of supporting a rod for optical transmission line spinning, which allows vertical spinning by holding a preform rod in a movable holder.

In a conventional method for supporting a rod for spinning optical transmission lines, the preform rod is fixed to a holding metal fitting, and the holding metal fitting is configured to be movable only in the vertical direction via a movable screw. Therefore, the spinning rod fixed to the holding metal fitting is supplied into the heating furnace through the holding metal fitting by rotating the movable screw, and is formed to be melt-spun in the heating furnace. The portion where the preform rod is held by the holding metal fitting and a small portion on the heating furnace side near the holding metal fitting do not enter the heating furnace. Therefore, apart from the preform rod, a holding glass rod made of quartz or the like is fused to the preform rod to hold the holding part of the holding fitting and a small portion on the heating furnace side near the holding fitting. It is well known that a method of spinning all of the rods is used. However, in the process of fusing the preform rod and the holding glass rod, it is desirable that both rods be fused without eccentricity, but it is unavoidable that the two rods become slightly eccentric during fusion. Therefore, due to the above-mentioned fusing error, the center of the preform rod does not match the center of the heating furnace during the stretch spinning process, and the preform rod is sent eccentrically through the heating furnace, resulting in spinning. As a result, the wire diameter of the optical transmission line fluctuates and the resin coating layer immediately after spinning is deflected. The present invention was made in order to solve the above-mentioned drawbacks, and the preform rod holding fittings are moved horizontally so that the central axes of the preform rod and the furnace are almost aligned due to the tensile force during spinning. It is an object of the present invention to provide a new method for supporting a freely movable optical transmission line spinning rod.

The method for supporting an optical transmission line spinning rod according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a perspective view showing an example of a conventional method for supporting a rod for optical transmission line spinning, in which a holding fitting 2 holding a preform rod 3 is movable vertically by rotation of a movable screw 1. The preform rod 3 is equipped with a nut 21 and a guide rod 22, and the preform rod 3 held by the holding metal fitting 2 is sent into a heating furnace 4, melted, and pulled by a pinch roller 6 for spinning. As mentioned above, the holding part of the preform rod 3 fuses the glass rod 31 made of quartz glass or the like and the preform rod 3 at the welding part 32, but generally during the welding, both rods are A slight eccentricity between the two is unavoidable, and it is therefore very difficult to align the center of the preform rod 3 with the center of the heating furnace 4. The eccentric rod will be eccentric to the center of the heating furnace, and the temperature distribution in the furnace will not match the center of the preform rod, which may cause fluctuations in the wire diameter of the optical transmission line after spinning. Often. In addition, optical transmission lines with varying wire diameters are coated with silicone resin, etc. (primary coat) immediately after spinning.
When performing this, there is a disadvantage that unevenness occurs in the film thickness of the resin coating. In the figure, 5 indicates the primary coat portion. FIG. 2 is a perspective view showing an embodiment of the method for supporting an optical transmission line spinning rod according to the present invention, and the same reference numerals are used for parts having the same functions as those in the previous figure.

As can be seen in the figure, by rotating the movable screw 1, the holding fitting 2 holding the preform rod 3 moves vertically, which is similar to the device used in the conventional method. Unlike the conventional fixed support, the holding part 7 of the rod 3 uses a spherical holding part 7 which is movably attached to the holding fitting 2 so that it can be horizontally movable supported. When the metal fitting 2 is lowered and the preform rod 3 is melt-spun in the heating furnace 4,
The tensile force of the pinch rollers 6 ensures that the center of the brief rod 3 always remains in the center of the heating furnace 4 during spinning. Therefore, even if the fused part 32 between the preform rod 3 and the holding glass rod 31 is slightly eccentric, since the holding part 7 is movable, the center of the furnace and the center of the spinning rod always coincide, so that The temperature distribution of the preform rod 3 becomes uniform, and variations in the wire diameter of the spun optical transmission wire are reduced, and the adverse effects caused by uneven thickness of the primary coat can also be eliminated. Another method of holding the preform rod in a movable manner is to hang the preform rod 3 with a metal wire, but since the temperature of the heating furnace is as high as 2000°C or more, it is difficult to hold the preform rod 3 due to convection. However, the preform rod will sway, making this application impossible.
As explained above, by applying the method for supporting an optical transmission line spinning rod according to the present invention, the process of fusing the preform rod and the holding glass rod can be simplified.
Since slight eccentricity is corrected by the tensile force of the pinch roller, fluctuations in the diameter of the optical transmission line can be reduced and the primary coat can be made uniform in thickness.

Therefore, it is possible to provide an inexpensive, high-performance optical transmission line, which is extremely advantageous especially when applied to the production of long optical transmission lines.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of a conventional method for supporting an optical transmission line spinning rod, and FIG. 2 is a perspective view showing an embodiment of a method for supporting an optical transmission line spinning rod according to the present invention. be. 1: Movable screw, 2: Holding metal fitting, 3: Preform rod, 4: Heating furnace, 5: Next coating section, 6: Pinch roller,
7: Movable holding part, 21: Movable nut, 22: Guide rod,
31: Glass rod for holding, 32: Fusion part.

Claims (1)

[Claims] 1. In a preform rod support device for supplying a preform rod of an optical transmission line into a heating furnace, a spherical holder is provided on the support device so that the spinning end of the preform rod can be moved freely in the horizontal direction. 1. A method for supporting an optical transmission line spinning rod, comprising: holding the spinning rod in the spherical holder, and stretching and spinning substantially in the direction of gravity.