JP2683757B2 - Glass base material support method and support structure thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention fixes a starting preform for forming a glass preform when producing a glass preform for an optical fiber by, for example, the VAD method or the OVD method. The present invention relates to a glass base material supporting method and a glass base material supporting structure.

<Prior art> As a glass base material manufacturing method, for example, the VAD method (Vapour
phase Axid Deposition) or OVD method (Outside Vapo
ur phase deposition) is known, for example, by forming glass fine particles such as quartz around the starting base material, and then heating and transparentizing the obtained starting material / glass fine particles composite, for example, an optical fiber. , We have obtained a glass base material used for glass substrates. At this time, the starting material / glass fine particle composite is subjected to a transparentizing treatment by connecting one end portion of the starting material to a supporting rod provided in a heating device. In the above method, various methods for supporting and fixing the starting material for forming the glass base material are known, and an example of the supporting structure is shown in FIGS. 3 and 4. As shown in FIG. 3 showing an example of a conventional supporting structure, a fitting opening 10b having a diameter substantially the same as that of the starting base material 11 is formed in the lower end portion 10a serving as a grip portion of the supporting rod 10, and this fitting is performed. A pin locking hole 10c facing the pin locking hole 11b provided on the upper end 11a of the starting base material 11 inserted into the joint 10b is provided. As a result, the starting base metal 11
Is inserted into the fitting port 10b, and the pin locking hole 11b and the pin locking hole
The starting base material 11 is fixed to the support rod 10 by inserting the pin 12 in the direction perpendicular to the axis while making the same with 10c.

Further, in the figure, reference numeral 13 indicates a glass particle deposit body deposited on the starting base material 10, reference numeral 14 indicates a core tube, and reference numeral 15 indicates a heater.

As shown in FIG. 4 showing an example of another conventional supporting structure, the head 21a of the starting base material 21 is attached to the lower end 20a of the supporting rod 20.
Is provided with a notch 22 for inserting and fixing
The head 21a of 21 is inserted and locked in the notch 22 so that the upper end of the starting base material 21 is fixed.

<Problems to be Solved by the Invention> However, the conventional methods for supporting the starting base material have the following problems.

When the starting base material and the glass fine particle composite are heated, the portion supporting the starting base material is simultaneously heated, and at the time of the heating, a constant stress is constantly applied to cause deformation of the starting base material. It becomes impossible to detach from the support rod due to the dropping of the starting base material or thermal expansion.

Also, in order to increase the outer diameter of the starting base material and eliminate heat conduction, the outer diameter of the starting base material is increased.
When the material cost is increased or the glass microparticles are formed, the heat capacity of the starting base material becomes large and sufficient heating cannot be performed, so that there is a problem that the glass microparticles cannot be formed well.

Furthermore, the distance from the end of the starting base material to the start of deposition of glass particles is lengthened so that the joint between the support rod where the stress is concentrated and the starting base material is not exposed to high temperatures. Since the length of the glass base material that can be manufactured is limited, it is necessary to substantially reduce the length of the glass particle deposit body. In view of the circumstances described above, the present invention is
An object of the present invention is to provide a glass base material supporting method and a glass base material supporting structure, which are particularly susceptible to thermal deformation and do not deform the supporting portion of the starting base material, and which are intended to lengthen the glass particulate deposition portion. .

<Means for Solving the Problems> The constitution of the method for supporting a glass preform of the present invention for achieving the above-mentioned object is as follows: when glass fine particles are deposited around the starting preform and then heated to be transparent and vitrified. In the method for supporting a glass base material, in which the end portion of the starting base material rotated around the vertical axis is engaged and supported by the starting base material support rod, the relationship between the starting base material support rod and the starting base material is It is characterized by engaging and supporting while cooling and cooling the joining / supporting part, and the structure of the supporting structure of one glass base material is the end of the starting base material that is rotated around the vertical axis during glass base material manufacturing. In a supporting structure of a glass base material, which is engaged and supported by engaging a portion with a locking hole formed at an end portion of the starting base material support rod, the glass base material is pierced in the axial direction of the starting base material support rod and is also supported. A cooling gas flow path communicating with the rod locking hole is provided in the starting base metal support rod. It is characterized by having.

<Operation> When glass particles are deposited on the starting base material and then vitrified, cooling gas is introduced into the engaging / supporting portion between the starting base material support rod and the starting base material through the gas flow passage, The engagement / support portion is cooled.

<Embodiment> Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

The same members as those of the conventional example are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 1, a starting base material support rod (hereinafter referred to as “support rod”) 100 has a gas passage 101 axially penetrating a central portion in a radial direction, and a fitting port 100 b of the support rod 100. The cooling gas G from a gas supply source (not shown) is introduced into the fitting port 10b. Examples of the cooling gas G for this cooling include inert gases such as nitrogen and helium.

Therefore, by the introduced cooling gas G, the support rod 10
The upper end portion of the starting base material 11 engaged and supported by the pin 12 at the fitting opening 100b at the lower end portion of 0 is cooled, and the glass viscosity of the support rod 100 and the starting base material 11 is increased when the glass is transparentized at high temperature. Is prevented from rising and thermal deformation is prevented.

Next, another embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 2, in the support rod 200 according to the present embodiment, a gas flow passage 210 that axially penetrates the central portion in the radial direction is communicated with a notch portion 202 formed in the support rod 200. The cooling gas G is introduced into the notch 202 as in the above-described embodiment.

Then, the head portion 201a of the starting base material 201 engaged in the cutout portion 202 is cooled by the cooling gas G. Further, in this starting base material 201, a gas flow path 211 is formed which axially penetrates the radial center portion of the upper end portion of the base material 201,
The cooling gas G introduced into the notch 202 of the support rod 200 is introduced into the starting base material 201, and the upper end portion of the starting base material 201 is further cooled from the inside. Therefore, in this embodiment, the gas flow path 210 and the starting base material 201 formed in the supporting rod 200 are formed.
By providing the communication member 212 that communicates with the internal gas flow path 211, the cooling gas G is directly sent efficiently. The communication member 212 is capable of moving up and down in the gas passage 210 formed in the support rod 200, and has gas passages 212a facing the gas passages 210 and 211 in the axial direction, respectively. Starting material in notch 202 formed in 200
When the 201 is engaged, it is moved upward in the drawing to be locked, and then it is lowered to communicate with the starting base material 201 gas flow passage 211.

As described above, by using the glass base material support structure according to the present embodiment, the durability of the support rod and the starting base material against heat is improved. Further, as shown in FIG. 1, the part 1 from the end of the starting base material to the start of forming the glass particle deposit 13 can be made shorter than before, and the effective base material length L that can be processed is reduced. It can be larger than before. Therefore, it is possible to make the base metal longer without significantly improving the equipment.

In the embodiment shown in FIG. 1 described above, a gas passage for introducing and cooling the cooling gas G is not provided at the upper end portion of the starting base material 11, but the gas passage is formed as in this embodiment. Of course, it may be formed.

Further, in the present embodiment, a gas flow path was formed in the central portion of the shaft of the supporting rod to cool the engaging / supporting portion between the starting base material and the supporting rod, but the method of the present invention does this. There is no limitation, and for example, a gas introduction pipe may be provided so as to be supplied to the engagement / support portion of the support rod and the starting base material for cooling, and the point is a structure for efficiently cooling the support portion. Any of them can be used.

<Test Example> Hereinafter, a test example showing the effect of the present invention will be described with reference to a comparative example.

Test Example This test was performed using the glass base material supporting device shown in FIG. 1 described above.

First, the tip has an outer diameter of 18φ mm and a length of 40 mm, and the outer diameter is 19φ.
mm 200 mm from the top edge of the starting base metal around the 900 mm long starting base metal
Using the glass base material with glass particles deposited from the position of, the end of this starting base material is supported by a pipe-shaped support rod with an inner diameter of 18.5φmm and an outer diameter of 30φmm, and the inner diameter is provided in the direction orthogonal to the axis.
A ceramic pin having an outer diameter of 4φ mm was inserted and fixed in the 4.5φ mm pin insertion hole. Next, the inside of the furnace core tube was heated to a high temperature while flowing the cooling gas through the cooling gas passage formed in the support rod at a rate of 20 l / min to make the glass transparent.

As a result, no deformation was observed in the supporting rod and the engaging / supporting portion of the starting base material.

Comparative Example The starting base material was supported using a conventional supporting rod having no cooling gas passage, and the same operation as in the above-mentioned test example was performed.

When the glass was made transparent, the upper part of the starting base material was stretched to a minimum diameter of about 10 mm, and the pin hole for locking the support rod and the starting base material was also deformed into an elliptical shape.

Further, in this comparative column, in order to prevent the deformation of the starting base material, it is necessary to deposit the glass fine particles with a length l of 400 mm or more from the upper end of the starting base material, which is more producible than the test example. Length L which is effective base metal length to win is 200m
It was necessary to make it shorter than m.

<Effects of the Invention> As described above in detail with the examples and test examples,
According to the present invention, it is possible to prevent thermal deformation of the support rod and the starting base material, and it is possible to increase the length of the base material for effective use without significant improvement.

[Brief description of the drawings]

FIG. 1 is a schematic view of a glass base material support structure according to an embodiment of the present invention, and FIG. 2 is a schematic view of a glass base material support structure according to another embodiment, FIGS. Each shows the schematic of the support structure which concerns on a prior art example. In the figure, 100 and 200 are supporting rods for the starting base metal, 11,201 are the starting base metal, 101, 210 and 211 are cooling gas passages, and G is cooling gas.

Claims (3)

(57) [Claims] 1. An end portion of a starting base material rotated around a vertical axis is engaged by a starting base material support rod when glass particles are deposited around the starting base material and then heated to be transparent and vitrified. In a method of supporting a glass base material for joining and supporting, a glass base material characterized by engaging and supporting while engaging and supporting portions of the starting base material support rod and the starting base material with cooling gas. Support method. 2. A glass mother which engages and supports by engaging an end portion of a starting mother material rotated around a vertical axis during manufacturing of a glass mother material with a locking hole formed in an end portion of a supporting rod for the starting mother material. In a supporting structure for a material, a glass is characterized in that a cooling gas flow path is provided in the starting base material supporting rod, the cooling gas passage penetrating in the axial direction of the starting base material supporting rod and communicating with the locking hole of the supporting rod. Base material support structure. 3. The glass base material support structure according to claim 2, wherein the starting base material support rod is provided with a gas flow passage.
A support structure for a glass base material, wherein a gas flow passage communicating with the gas flow passage is formed at an upper end portion of a starting base material to be supported.