JPH0449151Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a glass lathe, and in particular to a rotation introduction terminal (for connecting a reaction gas supply system and a reaction tube) in a glass lathe for manufacturing optical fiber preforms. (rotary joint).

[Prior Art] Conventionally, in glass lathes for producing optical fiber base materials, a rotating system is used between the gas piping system and the reaction tube in order to introduce raw material gas and reaction gas such as pure oxygen into the rotating reaction tube. terminal is used. This rotation introduction terminal has a fixed system connected to the gas piping system and a rotating system connected to the reaction tube, and these are connected by a rotating seal portion.

[Problems that the invention aims to solve] However, the raw material gas is generally SiCl ₄ or GeCl ₄
Because the gas is extremely corrosive, even a small amount of raw material gas leaks from the rotary seal portion, the rotary introduction terminal will be severely corroded. Also,
If such an abnormality occurs, there is a risk that impurities will be mixed in during glass production, leading to quality deterioration of the optical fiber base material.

Furthermore, even if there is no leakage of the raw material gas, the raw material gas itself reacts with a small amount of air, moisture, etc. remaining in the reaction system and generates impurities, so it is necessary to frequently disassemble and clean the rotary introduction terminal. There was a problem that working efficiency was reduced and the service life of the rotation introduction terminal was short.

Thus, the object of the present invention is to provide a glass lathe that eliminates the problems of the prior art described above, eliminates the need for frequent disassembly and cleaning of the rotating introduction terminal, and enables the production of high-quality optical fiber base materials. It is in.

[Means for Solving the Problems] In order to achieve the above object, the glass lathe of the present invention rotates the reaction tube around its axis and connects the open end of the reaction tube to the reaction gas supply system through the rotation introduction terminal. In a glass lathe, the distal end of the gas introduction tube has an outer diameter smaller than the inner diameter of the reaction tube, and is inserted into the reaction tube and is formed by these tubes. The seal gas is flowed into the gap between the

[Function] With this configuration, the highly corrosive raw material gas guided through the gas introduction tube is directly supplied into the reaction tube from the opening at the tip of the gas introduction tube. Then, a rotary seal part is used to airtightly connect the reaction tube and the gas introduction tube by flowing seal gas into the gap formed between the tip of the gas introduction tube inserted into the reaction tube and the reaction tube. This prevents the raw material gas from coming into contact with. Therefore, the rotary seal part will not corrode and the raw material gas will not leak therefrom.

Note that the flow rate of the seal gas should be kept to the minimum necessary since its purpose is to obtain sealing properties; for example, when using pure oxygen, it should be approximately 10% or less of the total amount of pure oxygen required for the reaction. It is preferable.

[Examples] Examples of the present invention will be described below with reference to the accompanying drawings.

FIG. 3 is a schematic diagram of a glass lathe according to an embodiment of the present invention. A pair of rotary supports 2 and 3 are provided on a base 1, and a burner 4 that can move between these rotary supports 2 and 3 is provided. Each of the rotary supports 2 and 3 is provided with chucks 6 and 7 for gripping and rotating the reaction tube 5, respectively. Further, a rotation introduction terminal 9 is disposed on the outside of the rotation support base 2 for airtightly connecting the open end of the reaction tube 5 held by the chuck 6 to a gas introduction tube from the gas supply device 8.

The feature of the present invention is the rotation introduction terminal 9, and FIG. 1 shows the detailed structure of the rotation introduction terminal 9.

A gas introduction pipe 10 for introducing a reaction gas into the reaction tube 5 is connected to the gas supply device 8 .
This gas introduction tube 10 has an outer diameter smaller than the inner diameter of the reaction tube 5, and a predetermined length of the tip thereof is the reaction tube 5.
inserted inside. Further, a connector 11 is provided on the outer periphery of the root portion of the gas introduction pipe 10, and is fixed to a body 13 on a support portion 12 via this connector 11. The body 13 has a long through hole with an inner diameter larger than the outer diameter of the gas introduction tube 10, and the gas introduction tube 10 is passed through and fixed in this through hole. With this, body 1
A gap 14 is formed between the gas introduction pipe 10 and the gas introduction pipe 10 . Further, as shown in FIG. 2, a seal gas supply pipe 15 for introducing seal gas into the cavity 14 is provided on the side of the body 13, and this seal gas supply pipe 15 is connected to the gas supply device 8. It is connected.

Further, a housing 16 is fitted onto the outer periphery of the front portion of the body 13 via a rotary seal portion 17, and is configured to be rotatable about the central axis of the gas introduction pipe 10. Here, the rotary seal portion 17 is formed of an oil seal 18 made of fluorocarbon rubber or the like, a pair of bearings 19 and 20, a spacer 21, and a stop ring 22.
A cap 23 is attached to the front surface of the housing 16, and the cap 23 and the end of the reaction tube 5 are airtightly connected by a tube 24 made of fluorocarbon rubber. In addition, in the figure, 25 indicates a hose band.

That is, the gap 14 formed between the body 13 and the gas introduction pipe 10 is kept airtight by the oil seal 18 of the rotary seal part 17 and the tube 24, and reacts along the outer circumference of the gas introduction pipe 10. It is connected to the inside of the pipe 5, and the seal gas supply pipe 1
5 through the gap 14 into the gap 26 between the gas introduction tube 10 and the reaction tube 5.

Next, the operation of this embodiment will be described.

First, the reaction tube 5 is rotated at a predetermined rotational speed by the rotary supports 2 and 3 and heated by the burner 4. At this time, the housing 16 rotates with respect to the body 13 via the rotary seal portion 17.

In this state, a vaporizer (not shown) or the like disposed in the gas supply device 8 supplies raw material gas (SiCl ₄ , GeCl _{4 ,} etc.) together with a carrier gas and a purge gas through the gas introduction pipe 10 into the reaction tube 5 . The above carrier gas or purge gas is fed from the seal gas supply pipe 15 into the gap 26 between the reaction tube 5 and the gas introduction pipe 10 as a seal gas.

As a result, a reaction such as SiCl ₄ +O ₂ →SiO ₂ +2Cl ₂ progresses in the reaction tube 5, and SiO ₂ is further vitrified. At this time, since there is a flow of sealing gas toward the inside of the reaction tube 5 in the gap 26 between the reaction tube 5 and the gas introduction tube 10, the raw material gas supplied into the reaction tube 5 from the tip opening of the gas introduction tube 10 is Gap 26
The water does not flow backwards and reach the rotary seal portion 17.
That is, the rotary seal portion 17 is protected by seal gas.

In this way, it was possible to manufacture the optical fiber base material while significantly reducing corrosion of the rotary seal portion and generation of impurities due to raw material gas.

[Effects of the invention] As explained above, according to the present invention, the following excellent effects are exhibited.

(1) Since direct contact of raw material gas to the rotary seal part is avoided by the seal gas, corrosion of this rotary seal part is prevented.

(2) Therefore, the life of the rotation introduction terminal can be extended, and the frequency of disassembly and cleaning can be reduced, thereby improving work efficiency.

(3) Since the generation of impurities and gas leaks due to corrosion are prevented, it is possible to stably manufacture high-quality optical fiber base materials.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the configuration of a rotation introduction terminal used in a glass lathe according to an embodiment of the present invention, Fig. 2 is a view taken along the - arrow in Fig. 1, and Fig. 3 is a schematic diagram of the embodiment. FIG. 2 is an overall diagram showing the configuration. In the figure, 5 is a reaction tube, 8 is a gas supply device, 10 is a gas introduction tube, 13 is a body, 15 is a seal gas supply tube, 16 is a housing, 17 is a rotary seal part,
26 is a gap.

Claims (1)

[Scope of utility model registration request] In a glass lathe in which a reaction tube is rotated around its axis and the open end of this reaction tube is hermetically connected to a gas introduction tube connected to a reaction gas supply system through a rotating introduction terminal, the tip of the gas introduction tube is A glass lathe characterized in that the lathe has an outer diameter smaller than the inner diameter of the reaction tube and is inserted into the reaction tube and allows sealing gas to flow through the gap formed by these tubes.