JP2003212551A - Method and apparatus for manufacturing glass preform - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for manufacturing a glass preform in which a fine glass particle deposit is formed based on an outside vapor deposition method and it is made into clear glass. <P>SOLUTION: An accumulative layer 3 of the fine glass particle is formed on a starting glass rod 1 rotating while reciprocating in an axial direction by a burner 9 for producing the fine glass particle. Then, the accumulative layer 3 is heated to obtain the clear glass. The accumulative layer 3 is made into the clear glass whenever the starting glass rod 1 reciprocates by a heating means 12 arranged at one side or both sides of the burner 9. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a glass base material in which glass particles are deposited on a starting glass rod by flame hydrolysis and then vitrified into a transparent glass.

[0002]

2. Description of the Related Art OVD method (external vapor deposition method) is known as a method for producing a cylindrical glass preform such as an optical fiber. In this method, for example, a starting glass rod is reciprocally moved in the axial direction in a reaction vessel and is rotated while a glass raw material gas such as SiCl ₄ or GeCl _{4 is} supplied to the outer periphery thereof, a fuel gas such as H ₂ and O ₂ or the like. It is sprayed from a burner together with the auxiliary gas of No. 3, and glass fine particles are generated and deposited by a flame hydrolysis reaction to prepare a glass fine particle deposit body. Then, the glass fine particle deposit is dehydrated and fired in a sintering furnace or the like to be a transparent glass.

Conventionally, a step of producing a glass particulate deposit body composed of a deposited layer of glass particulates in a reaction vessel, and then transferring the glass particulate deposit body to a transparent furnace to obtain transparent vitrification is performed. When transferring from the reaction vessel to the sintering furnace, the glass particle deposit immediately after being produced is at a high temperature, so it will be taken out from the reaction vessel after the temperature has dropped to some extent, and time is required for this. .
Then, the glass particulate deposit is taken out of the reaction vessel,
The transfer to the next sintering furnace and the attachment to the sintering furnace are performed, but the working time for this is required. Further, since the glass fine particle deposit body is in a mechanically brittle state, there is a risk of being scratched or damaged during these operations.

In the sintering furnace, after the glass particulate deposit is attached, the temperature required for vitrification (eg 16).
It takes time to raise the temperature to about 00 ° C. When the temperature is raised at once, bubbles may be generated in the transparentized glass due to the difference in density between the inner part and the outer part of the deposited layer of glass particles. In order to improve this, 1100 ℃ ~
After preliminary calcination at 1300 ° C., main calcination at 1400 ° C. to 1600 ° C. (see JP-A-61-97141), or dehydration treatment at 1100 ° C. to 1400 ° C. and then 1
A transparent glass is formed at 500 ° C to 1900 ° C (JP-A-61).
In some cases, a stepwise heat treatment such as the one described in Japanese Patent Publication No. 72644) is required.

In the VAD method (method with a vapor phase axis), there is known a method in which a glass fine particle deposit is produced and subsequently subjected to a heat treatment to form a transparent vitrification (for example, JP-A-58).
-9835). According to this method, since the sintering furnace is not transferred from the reaction vessel, it is possible to avoid shortening the manufacturing time and damaging the glass particulate deposit. However, since the VAD method deposits glass fine particles in the axial direction to produce a glass fine particle deposit, it is possible to sequentially heat the deposited portions in the axial direction to form transparent vitrification. On the other hand, in the OVD method, glass particles are deposited in the radial direction of the starting glass rod while moving the starting glass rod and the burner relatively in the axial direction. Therefore, heat treatment for transparent vitrification is performed until the final layer is deposited. Therefore, it is impossible to carry out a treatment by continuous heating like the VAD method.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and a method and a method for producing a glass base material capable of producing a glass particle deposit by the OVD method and at the same time making it vitrified. The object is to provide a device.

[0007]

According to the method for producing a glass preform of the present invention, a glass fine particle deposition burner is used to form a deposited layer of glass fine particles on a starting glass rod that reciprocates in the axial direction and rotates. A method for producing a glass base material, which comprises heating a deposited layer of fine particles to form transparent glass,
It is characterized in that the deposited layer of glass particles is made into transparent glass every time the starting glass rod reciprocates by the heating means arranged on one side or both sides of the burner for producing glass particles.

The glass base material manufacturing apparatus of the present invention is
It is a glass base material manufacturing device that forms a deposited layer of glass particulates on a starting glass rod that reciprocates in the axial direction and rotates with a burner for producing glass particulates, and heats the deposited layer of glass particulates to form transparent glass. The heating means is arranged on one side or both sides of the burner for producing fine glass particles, and the deposited layer of fine glass particles is transparentized by the heating means every time the starting glass rod reciprocates.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIG. FIG. 1A is a schematic view showing an example in which an electric heater is used as the heating means of the glass base material manufacturing apparatus.
(B) is a view showing a cross section of a burner for producing glass particles to be used. In the figure, 1 is a starting glass rod, 2 is a dummy rod, 3 is a deposited layer of glass fine particles, 4 is a supporting rod, 5 is a lifting / lowering rotating device, 6 is a reaction vessel, 7 is an upper core tube, 8 is a lower core tube, 9 is a burner for producing fine glass particles, 10 is an exhaust pipe,
Reference numeral 11 is a gas introduction pipe, and 12 is a heating means.

The starting glass rod 1 serves as a base material for depositing glass fine particles on the outer peripheral surface, and is made of a glass material similar to the glass formed on the outer peripheral surface.
When manufacturing a glass preform composed of a core part and a clad part for an optical fiber, it is possible to use only a core glass doped with germanium or the like to increase the refractive index, or a core rod made of a core glass and a clad glass. .

Dummy rods 2 also made of a glass material are connected to both ends of the starting glass rod 1 by fusion bonding, and one dummy rod (upper side) is fixed to a support rod 4 and is suspended and supported. The support rod 4 is rotated and reciprocally moved in the vertical direction by an elevating / rotating device 5 to drive and control the starting glass rod 1. The glass base material manufacturing apparatus has an upper furnace core tube 7 (also referred to as an upper chimney when heating means is not provided) above the reaction vessel 6 and a lower furnace core tube 8 (downside when heating means is not provided) below. It also has a chimney). The reaction vessel 6, the upper core tube 7 and the lower core tube 8 are all made of quartz.

Glass particles are produced in the reaction vessel 6.
A plurality of burners 9 for producing fine glass particles for
Has been. The burner 9 for producing fine glass particles is, for example,
Three burners are provided at 150 mm intervals. This moth
The burner 9 for producing lath particles is shown in the cross section of FIG.
As shown in FIG._FourAnd GeC
l_Four) Jetting port 9a, the sealing gas on the outside
A port 9b for ejecting (Ar) is provided.
It On the outside of the port 9b, hydrogen gas (H ₂)
Port 9c for ejecting oxygen and oxygen gas (O₂)
A large number of small ports 9d that spout
And a port 9e are provided coaxially. Also, anti
Discharge the glass particles etc. floating in the container 6
An exhaust pipe 10 is provided.

The upper furnace core tube 7 is provided with a gas introduction tube 11 for introducing chlorine gas and helium gas for promoting dehydration and sintering of the deposited layer of glass fine particles. In addition, the gas introduction pipe 11
May be provided on the lower reactor core 8 side, or may be provided on both the upper reactor core 7 and the lower reactor core 8. Exhaust of these gases is performed by the exhaust pipe 10 provided in the reaction vessel 6, but a dedicated exhaust pipe may be provided separately. The upper core tube 7 and the lower core tube 8 are
Both ends 3a and 3b of the deposited layer 3 of glass particles have a length that can be accommodated at the same time, and they are integrally sealed in the upper and lower sides of the reaction vessel 6 in a sealed manner. In the present invention, the heating means 12 is arranged outside either one or both of the upper core tube 7 and the lower core tube 8. FIG. 1 shows an example in which the heating means 12 is attached only to the lower furnace core tube 8 side and an electric heater 13 is used as the heating means 12.

The electric heater 13 includes, for example, a heater element 13a such as a carbon resistor covered with a heat insulating material 13b.
A metal furnace body 13c made of stainless steel or the like is used. In the heating means 12, the distance D between the end of the heater element 13a that contributes to actual heating and the end of the burner 9 for producing glass particles closest to the end is 100 mm to.
It is preferable to arrange so as to be 300 mm. If the distance D is less than 100 mm, the heating means 12 may be deteriorated by the heat of the flame of the burner 9 for producing glass particles. Further, when it exceeds 300 mm, it takes too much axial movement time to make the deposited layer 3 of glass particles into a transparent glass, and the apparatus itself becomes large, resulting in poor productivity.
If the heating means is a burner, the lower limit side is 20 mm.
As mentioned above, when the heating means is a laser, the lower limit side is 10 mm.
The above is preferable.

The axial length E of the heater element 13a that actually contributes to the heating of the heating means 12 is preferably 50 mm to 200 mm in the case of an electric heater. In addition,
The burner preferably has a diameter of 30 mm to 200 mm, and the laser has a diameter of 1 mm to 100 mm. In order to uniformly make the deposited layer 3 of glass fine particles into transparent glass, it is necessary to move each part of the deposited layer 3 of glass fine particles back and forth by the length of the heater element 13a that contributes to heating. If the heater element 13a is too long in the axial direction, the distance for reciprocating movement becomes long, and it takes time and the apparatus becomes large in size, which is not good in productivity. However, even if it is too short, the heating necessary for making it into a transparent glass cannot be performed, so the above range is preferable.

Next, a method of manufacturing the glass preform with the manufacturing apparatus having the above-mentioned structure will be described. First, one of the dummy rods 2 attached to both ends of the starting glass rod 1 is attached to the supporting rod 4 of the elevating and rotating device 5, and the elevating and rotating device 5 moves the starting glass rod 1 downward while rotating it. At the stage where the starting glass rod 1 has entered the reaction vessel 6, the production of glass particles is started by the burner 9 for producing glass particles, and the deposition layer 3 of the first layer of glass particles is formed on the outer peripheral surface of the starting glass rod 1. (Hereinafter, referred to as the first deposition layer 3) are sequentially formed along the axial direction.

The deposited layer 3 of the first layer, which has been deposited, sequentially enters the lower furnace core tube 8 from the lower end 3a side thereof,
It is heated at a high temperature by the heating means 12 arranged outside the. By this heating, the first deposited layer 3 is dehydrated and transparent vitrification proceeds. Further, the inside of the lower furnace tube 8 is in an atmosphere containing chlorine gas and helium gas introduced from the gas introduction tube 11, and the dehydration and transparent vitrification of the first deposited layer 3 are promoted. First layer of deposition layer 3
When the upper end 3b of the starting glass rod 1 passes through the heating means 12, the starting glass rod 1 is reversed from the downward movement to the upward movement.

When the moving direction of the starting glass rod 1 is reversed to the upward direction, the first deposited layer 3 is heated by the heating means 12.
Is heated again and transparent vitrification is performed. By this reciprocating heating, the vitrification of the first deposited layer 3 is completed, and the burner 9 for producing fine glass particles is moved by the upward movement.
The second layer of glass fine particles is deposited on the transparent vitrified glass layer. The second deposited layer 3 sequentially enters the upper core tube 7 to form the lower end 3a of the deposited layer.
At the end of the deposition, the starting glass rod 1 is reversed from the upward movement to the downward movement at the start.

On the side of the upper core tube 7 as well as the lower core tube 8,
In the case where the heating means 12 is arranged, the second deposited layer 3
Is dehydrated in the same manner in the upper furnace tube 7 to be transparent vitrified. When the heating means 12 is not provided in the upper furnace core tube 7 as shown in FIG. 1, the upper furnace core tube 7 serves as an evacuation chamber for depositing glass particles in a predetermined range.

With the downward movement of the starting glass rod 1,
Following the formation of the second deposited layer, the third deposited layer is formed. Next, the second and third layers of the glass particulate deposited layer 3 enter the lower furnace tube 8 and are dehydrated by the heating means 12 to be transparent vitrified in the same manner as the first layer of the deposited layer 3. After that, the same reciprocating movement causes the glass glass particles to be repeatedly deposited and vitrified every time the starting glass rod 1 reciprocates, thereby manufacturing a glass base material having a predetermined outer diameter.

According to the above-mentioned method for producing a glass base material, transparent vitrification is performed every time a thin deposited layer of glass particles is formed. Therefore, the deposition of glass particles and the transparent vitrification thereof are carried out simultaneously. Will be done. Therefore, as in the conventional method, a glass particle deposit is prepared in a reaction vessel,
It is possible to perform the two processing operations of transferring this to a sintering furnace and making it transparent glass in one processing operation, and it is possible to reduce the manufacturing time and the amount of work. Also,
Since there is no need to transfer from the reaction vessel to the sintering furnace,
This does not cause damage to the glass particulate deposit.
Further, since each thin deposited layer of glass particles is made into transparent glass, the problem of leaving voids inside the glass can be solved.

Next, a specific example (1) according to the embodiment of FIG. 1 will be described. The electric heater 13 of the heating means has an axial length E of the carbon heater element 13a.
However, it was arranged so that the distance D between the lower end of the glass fine particle generating burner 9 closest to the upper end of the heater element and the lower end of the heater element was 100 mm. The starting glass rod 1 was a core rod composed of a core glass and a clad glass, and had a diameter of 30 mm and a length of 500 mm. Dummy rods 2 of the same diameter are attached to both ends of this starting glass rod 1.
Was welded, and one dummy rod was attached and fixed to the support rod 4. The elevating and rotating device 5 moves the starting glass rod 1 to 40
50mm / min while rotating at rpm
At a speed of 1300 mm in the vertical direction (the length of the glass particulate deposition layer 3 is 1100 mm + the heating distance of the heating means is 200 m).
It was moved. In addition, chlorine gas (Cl ₂ ) 2SLM, helium gas (H
e) 30 SLM was supplied through the gas introduction pipe 11.

The burner 9 for producing fine glass particles in the reaction vessel 6 was provided with three burners having a diameter of 30 mm at intervals of 150 mm. Burner 9 for producing each glass particle
Is a glass raw material of silicon tetrachloride (SiCl ₄ ) 4 to 6
SLM (standard liter / min), hydrogen gas (H ₂ ) for forming a flame of 50 to 80 SLM, oxygen gas (O ₂ ) of 40 to 80 SLM, and argon (Ar) as a sealing gas of 6 SLM were supplied. . For the electric heater 13, the power supply was adjusted so that the temperature of the heater surface at the center of the heater was 1600 ° C. The deposition and transparent vitrification were repeated until the increased weight of glass reached 10 kg, and the time required for this was 11H.

As a comparative example, the heating means 12 shown in FIG.
Was removed, and only glass fine particles were deposited. After that, dehydration firing was performed in a sintering furnace with a heater length of 400 mm. As the starting glass rod 1, a core rod having a diameter of 30 mm and a length of 500 mm, which was the same as in Example 1, was used, dummy rods 2 were welded to both ends thereof, and one dummy rod was supported by a support rod 4.
40 rpm of the starting glass rod 1 by the elevating / rotating device 5.
While rotating at a rotation speed of m, it was moved vertically by 1100 mm at a speed of 50 mm / min.

The burner 9 for producing fine glass particles in the reaction vessel 6 was provided with three burners having a diameter of 30 mm at intervals of 150 mm. Burner 9 for producing each glass particle
Is a glass raw material of silicon tetrachloride (SiCl ₄ ) 4 to 6
SLM, hydrogen (H ₂ ) for forming a flame of 50 to 8
0 to 20 SLM and oxygen (O ₂ ) were supplied at 40 to 80 SLM, and further 6 SLM of argon (Ar) was supplied as a gas for sealing. The deposition was repeated so that the increased weight of glass was 10 kg, and the time required for this was 8H. Further, this was dehydrated and fired in another sintering furnace to form a transparent glass, and the time required for this was 8H. It took 16 hours from the start of the deposition of the glass particles to obtain a transparent glass base material.

In FIG. 2, an oxyhydrogen burner is used as the heating means.
A specific example 2 will be described below. The symbols in the figure are
Detailed description using the same reference numerals as used in FIG.
Is omitted. In this example, the heating means 12 is, for example,
For example, make four mounting holes around the lower furnace tube 8
The burner 14 for heat is attached and comprised. Each heating bar
The ner 14 actually contributes to the heating of the deposited layer of glass particles.
The spread of the flame (corresponding to the axial length E of the heating means)
It was adjusted to be about 80 mm. Also a heating bar
The gnar 14 is the glass closest to the top of the burner spread.
The distance D from the lower end position of the fine particle generation burner 9 is 2
It was set so as to be about 0 mm. And heating four
Hydrogen (H₂) 100 SL
M, oxygen (O ₂) Of 50 glass is supplied to
The temperature of the surface of the deposited layer was set to 1550 ° C.
In addition, a gas introduction pipe 11 is installed in the reaction vessel and the core tube.
Chlorine gas (Cl₂) 2SLM, helium gas (H
e) Supplied 30 SLM.

As the starting glass rod 1, a core rod made of core glass and clad glass having a diameter of 30 mm and a length of 500 mm was used as in the example of FIG. Dummy rods 2 having the same diameter were welded to both ends of this starting glass rod 1, and one dummy rod was attached and fixed to the support rod 4. The elevating and rotating device 5 moves the starting glass rod 1 to 100 rpm.
While rotating at a rotation speed of 1, the glass was moved vertically at a speed of 50 mm / min by 1200 mm (the length of the deposition layer 3 of glass particles is 1100 mm + the heating distance of the heating means is 100 mm).

The burner 9 for producing fine glass particles in the reaction vessel 6 has a burner 3 having a diameter of 30 mm, as in the example of FIG.
Books were placed at 150 mm intervals. Each of the burners for producing fine glass particles contains silicon tetrachloride (Si
Cl ₄ ) for ₄ to 6 SLM, hydrogen (H ₂ ) for forming a flame of 50 to 80 SLM, and oxygen (O ₂ ) to 40.
˜80 SLM and 6 SLM of argon (Ar) as a gas for sealing were supplied. Increased weight of glass is 10
The deposition and the transparent vitrification were repeated until Kg was reached, and the time required for this was 10H. In the example of FIG. 2 described above,
An example using an oxyhydrogen burner as the heating burner has been shown, but the same effect can be obtained by using another burner, for example, a plasma burner.

FIG. 3 shows an example in which a high-power high-power laser is used as the heating means, which will be described as a third specific example. The reference numerals in the figure are the same as those used in FIG. In this example, as the heating means 12, for example, a laser beam passage hole is provided in the lower core tube 8.
The surface of the deposition layer 3 of glass particles is heated by the laser light of the high-power laser 15. A YAG laser was used as the high-power laser 15, and the YAG laser was installed such that the laser light was at a distance of about 30 mm from the lower end position of the glass particulate generation burner 9 closest to the reaction vessel 6. The spot diameter of the laser beam was set to 20 mm, and the surface temperature of the glass particle deposition layer 3 at the laser irradiation point was set to 1550 ° C. In addition, chlorine gas (Cl ₂ ) ₂ SLM and helium gas (He) 30 SLM are introduced into the reaction vessel and the core tube through the gas introduction pipe 11.
Was supplied.

As the starting glass rod 1, a core rod made of a core glass and a clad glass having a diameter of 30 mm and a length of 500 mm was used as in the example of FIG. Dummy rods 2 having the same diameter were welded to both ends of this starting glass rod 1, and one dummy rod was attached and fixed to the support rod 4. The elevating and rotating device 5 moves the starting glass rod 1 to 100 rpm.
While rotating at a rotational speed of 1 mm, it was moved at a speed of 50 mm / min in the vertical direction by 1150 mm (the length of the deposition layer 3 of glass particles was 1100 mm + the heating distance of the heating means was 50 mm).

The burner 9 for producing fine glass particles in the reaction vessel 6 has a burner 3 having a diameter of 30 mm, as in the example of FIG.
Books were placed at 150 mm intervals. Each of the burners for producing fine glass particles contains silicon tetrachloride (Si
Cl ₄ ) for ₄ to 6 SLM, hydrogen (H ₂ ) for forming a flame of 50 to 80 SLM, and oxygen (O ₂ ) to 40.
˜80 SLM and 6 SLM of argon (Ar) as a gas for sealing were supplied. Increased weight of glass is 10
The deposition and the transparent vitrification were repeated until Kg was reached, and the time required for this was 9.5H.

[0032]

As is apparent from the above description, according to the present invention, the deposition of glass fine particles and the transparent vitrification can be simultaneously carried out in the manufacturing apparatus including the reaction vessel, which shortens the manufacturing time and the work. The amount can be reduced. Also,
The occurrence of damage to the glass base material can be reduced, and the problem of leaving voids inside the glass can be solved.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating an outline of an embodiment of the present invention and a specific example (1).

FIG. 2 is a schematic diagram illustrating a specific example (2) of the present invention.

FIG. 3 is a schematic diagram illustrating a specific example (3) of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Starting glass rod, 2 ... Dummy rod, 3 ... Deposited layer of glass fine particles, 4 ... Support rod, 5 ... Lifting / rotating device, 6 ... Reaction vessel, 7 ... Upper core tube, 8 ... Lower core tube, 9 ... Glass Burner for producing fine particles, 10 ... Exhaust pipe, 11 ... Gas introduction pipe, 1
2 ... Heating means, 13 ... Electric heating heater, 14 ... Heating burner, 15 ... High power laser.

Claims (8)

[Claims] 1. A glass mother which forms a deposited layer of glass fine particles on a starting glass rod that reciprocates in the axial direction and rotates by a burner for producing glass fine particles, and heats the deposited layer of the glass fine particles to form transparent glass. A method of manufacturing a material, characterized in that a heating means arranged on one side or both sides of the burner for producing glass fine particles makes the deposited layer of the glass fine particles transparent glass every time the starting glass rod reciprocates. A method for manufacturing a glass base material. 2. The method for producing a glass base material according to claim 1, wherein the deposited layer of the glass fine particles is heated in an atmosphere containing chlorine gas and an inert gas to form a transparent glass. 3. The length of the heating means in the longitudinal direction is 200 m.
m or less, The manufacturing method of the glass base material of Claim 1 or 2 characterized by the above-mentioned. 4. The method for producing a glass preform according to claim 1, wherein the distance between the heating means and the burner for producing glass particles is 300 mm or less. 5. The method for producing a glass preform according to claim 1, wherein an electric heater is used as the heating means. 6. The method for producing a glass preform according to claim 1, wherein a heating burner is used as the heating means. 7. The method for producing a glass preform according to claim 1, wherein a high-power laser is used as the heating means. 8. A glass mother which forms a deposited layer of glass fine particles on a starting glass rod which reciprocates in the axial direction and rotates by a burner for producing glass fine particles, and heats the deposited layer of the glass fine particles to form transparent glass. In the apparatus for manufacturing a material, heating means is arranged on one side or both sides of the burner for producing glass particles, and each time the starting glass rod reciprocates, the deposited layer of glass particles is vitrified by the heating means. A glass base material manufacturing apparatus characterized by the above.