JP2003267736A - Sintering furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shielding device which is structured so that the part in which clouding has occurred can be easily replaced, in order to cope with the occurrence of the clouding in a shielding device for shielding the internal space of a core tube and providing airtight to the portion where a deposited body of glass fine particles is housed. <P>SOLUTION: A sintering furnace 10 has a carbon core tube 11 housing the deposited body of glass fine particles 1 in which glass fine particles are deposited and the shielding device 30 for shielding the core tube 11, wherein the deposited body of glass fine particles 1 housed in the core tube 11 is heated to undergo dehydration/sintering. The shielding device 30 is provided with replaceable sleeves 36 and 37 on a part of the inner wall, and is designed such that when the clouding has occurred due to the product attached during the operation of the sintering furnace 10, only the sleeves 36 and 37 are replaced. Such a structure eliminates the operation in which the sintering furnace 10 is disassembled and the whole shielding device 30 is replaced, and allows the cloudy part to be renewed without excessively reducing the rate of operation of the sintering furnace 10. <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 sintering furnace for producing a glass base material used as a preform for an optical fiber or the like by dehydrating / sintering a glass particulate deposit to form a transparent glass.

[0002]

2. Description of the Related Art As a method for manufacturing a cylindrical glass preform used as a preform for optical fibers, for example, OVD is used.
The method (external vapor deposition method) is known. This method
The starting material glass rod such as SiCl ₄ and GeCl ₄ , the fuel gas such as H ₂ and the supporting gas such as O ₂ are ejected from the burner while reciprocating and rotating the starting glass rod in the reaction vessel in the axial direction. Then, by hydrolyzing and oxidizing in the flame of the burner, a base material of glass particles is generated, and this is deposited on the outer circumference of the starting glass rod to prepare a glass particle deposit body (soot body). After that, the glass particle deposit is transferred to a sintering furnace and dehydrated /
A transparent glass is formed by sintering.

Dehydration treatment is carried out by, for example, adding SiCl in a sintering furnace.
It is carried out by heating the glass fine particle deposit while flowing a chlorine-based dehydrating agent such as ₄ together with He gas,
Further, the subsequent sintering treatment is performed by heating the glass fine particle deposit in an inert gas such as He gas under a higher temperature atmosphere than the dehydration treatment.

FIG. 3 is a view for explaining a sintering furnace for dehydrating / sintering the glass particle deposit body (soot body) as described above to form a transparent glass, and the operation of the dehydration / sintering process. FIG. 3 (A) to FIG. 3 (D) sequentially show the operation of accommodating the glass particle deposits in the sintering furnace in a schematic configuration diagram. In FIG. 3, 1 is a glass particle deposit, 10 is a sintering furnace as an apparatus, 11 is a carbon furnace core tube, 12 is a quartz furnace core tube, 13 is a furnace body which is a part of the sintering furnace, 20 Is an elevating device, 21 is a hanging rod, 22 is a storage case upper lid, and 30 is a furnace core tube shielding device (gate valve).

FIG. 4 is a schematic side view for explaining the internal structure of the shielding device (gate valve) 30 in the sintering furnace 10 shown in FIG. 3, in which 31 is a shielding device main body and 31a.
Is a flange portion, 31b is a sleeve-shaped valve storage case, 3
2 is a valve element, 33 is a valve element support member, 34 is a light source, and 35 is an optical sensor.

As a sintering furnace for dehydrating / sintering the glass particulate deposit, the one having a structure as shown in FIGS. 3 and 4 is usually used. In the sintering furnace 10, a carbon-made furnace core tube 11 and a quartz-made furnace core tube 12 whose surfaces are airtightly penetrated through a furnace body 13 are arranged coaxially, and a carbon furnace core tube is connected to these connecting portions. A shielding device 30 for shielding 11 from the quartz furnace core tube 12 is provided. The carbon furnace core tube 11 is arranged inside the furnace body 13, and the furnace body 13 includes
A heater (not shown) and a heat insulating material around the heater are arranged. The glass particle deposit 1 is housed in this and heated to perform dehydration / sintering treatment on the glass particle deposit 1. In the dehydration / sintering process of the glass particle deposit body using the sintering furnace 10 as described above, as shown in FIG. The glass particulate deposit 1 is suspended and supported (FIG. 3A), and the elevating device 20 is operated to store the glass particulate deposit 1 inside the furnace core tubes 11 and 12 (FIG. 3B to FIG. In FIG. 3 (D), a small dehydration / sintering process is performed.

In the sintering furnace 10, the carbon furnace core tube 1 is connected to the carbon furnace core tube 11 and the quartz furnace core tube 12 at the connecting portion.
1. A shielding device 30 shown in FIG. 4 for shielding the inner space of
Is provided. The shielding device 30 includes a valve body 32 supported by a valve body supporting member 33 such as a rod as a shield, and the valve body 32 is integrally formed with a sleeve-shaped valve storage case 31b and a quartz flange portion 31a. It is housed in the shield device main body 31. As shown in FIG. 3 (D), when the glass particle deposit body 1 is housed in the carbon furnace core tube 11, the dehydration / sintering process is performed with the valve body 32 moved to the open side. To do.

In the sintering furnace 10 as described above, in order to confirm the storage state of the glass particle deposit 1, the light source 34 for detecting the glass particle deposit 1 and the vicinity of the outer periphery of the shielding device body 31 are provided. An optical sensor 35 is provided. The light source 34 and the optical sensor 35 are provided outside the shielding device body 31 so as to face each other with the shielding device body 31 interposed therebetween. When the light source light emitted from the light source 34 passes through the quartz shielding device body 31 and is received by the optical sensor 35 on the opposite side, the presence or absence of the glass particulate deposit 1 is detected, and the carbon furnace is thus detected. Core tube 11
The position of the glass particle deposit body 1 is checked during the storage operation of the glass particle deposit body 1 with respect to.

As described above, in the shielding device 30 having the quartz shielding device main body 31 and the valve body 32, the glass fine particle deposit 1 is detected by light, and the inside of the shielding device 30 is passed through the shielding device 30. An operator or the like visually observes the state of the glass particulate deposit 1 and the state of the inner surface of the carbon furnace core tube 11.

[0010]

In the above-described sintering furnace, deposits adhere to the inner surface of the sintering furnace as the sintering furnace operates, and the quartz shielding device 30 also becomes cloudy due to the deposits. . The above-mentioned deposit is the dehydrating agent SiCl
₄ and the O ₂ in water and in the air contained in the glass particles deposit 1 is believed to be a SiO ₂ produced in response to as shown in the following reaction scheme. SiCl ₄ + O ₂ = SiO ₂ + 2Cl ₂ SiCl ₄ + 2H ₂ O = SiO ₂ + 4HCl

The above-described position detection function by the optical sensor and the function that enables visual observation are impaired by the fogging of the shielding device 30. Therefore, when the above-mentioned fogging occurs, the shielding device 30 itself is replaced. is doing.

Further, an oxidation resistant coating (SiC, etc.)
The components not subjected to the above process react with oxygen in the atmosphere in a high temperature atmosphere of 400 ° C. or higher inside the furnace core tube 11 made of carbon to be oxidized and consumed, so that the sintering furnace is replaced when the shielding device 30 is replaced. It is necessary to lower the temperature of the whole, and the operating rate of the equipment decreases. Further, the work of installing the shielding device 30 itself needs to be installed accurately so that the processing gas, which is a toxic gas, does not leak to the outside. Therefore, a considerable work time is required, which causes a decrease in the operating rate of the sintering furnace. Has become.

The present invention has been made in view of the above-mentioned circumstances, and in a sintering furnace for dewatering / sintering glass particulate deposits (soot body) to obtain transparent glass, the inside of the furnace core tube is In order to cope with the occurrence of fogging in the shielding device for shielding the space and hermetically storing the accommodating portion of the fine glass particle deposit, the fogging portion is configured to be easily replaced. This eliminates the work of disassembling the sintering furnace and replacing the entire shielding device, which enables regeneration of the cloudy portion without significantly reducing the operating rate of the sintering furnace. The purpose is to provide a furnace.

[0014]

A sintering furnace of the present invention has a furnace core tube for accommodating a glass particle deposit body in which glass particles are deposited, and a shielding device for shielding the furnace core tube, In a sintering furnace for heating and dehydrating / sintering a glass particulate deposit housed in a furnace core tube, a part of an inner wall of the shielding device is configured as a replaceable member in a sintering furnace. And

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic side view for explaining an example of the internal structure of a shielding device in a sintering furnace according to the present invention, in which 36 is an upper sleeve and 37 is a lower sleeve. Other parts having the same functions as those in FIG. 4 are denoted by the same reference numerals as those in FIG. According to this embodiment, a sleeve (upper sleeve 36, lower sleeve 37) that can be easily removed is provided inside the shielding device 30.
That is, the quartz sleeves 36 and 37 are arranged on the inner peripheral surface of the portion of the quartz shielding device main body 31 through which the glass particle deposit body 1 passes. The upper sleeve 36 and the lower sleeve 37 are arranged above and below the valve body 32, respectively.

Si produced by the operation of the sintering furnace 10
When the shielding device 30 is fogged due to the adherence of O ₂ , conventionally, it was necessary to replace the shielding device 30 itself. However, according to the configuration of the present invention, the upper sleeve 36 and the lower sleeve 36 are By replacing one or both of the sleeves 37 as needed, the function recovery process can be performed by a simple operation.

Basically, the optical sensor 35 as described above is used.
Since the detection of the glass particulate deposit 1 and the visual observation of the internal state by the above are performed at the portion where the upper sleeve 36 is provided, the upper sleeve 36 may be replaced in order to deal with fogging. At this time, by moving the valve body 32 to the shielding position, the upper sleeve 36 can be replaced without lowering the temperature inside the carbon furnace core tube 11, and the operating rate of the sintering furnace 10 can be significantly increased. It is possible to regenerate the cloudy portion without lowering the temperature. Further, since the arrangement portion of the lower sleeve 37 does not affect the position detection of the optical sensor 35, the replacement frequency may be less than that of the upper sleeve. When replacing the lower sleeve 37, since the valve body 32 needs to be moved to the open position, the inside of the carbon furnace core tube 11 is cooled, but since the replacement of the lower sleeve 37 is simple, It is possible to minimize the decrease in the operating rate of the sintering furnace.

In the upper sleeve 36 and the lower sleeve 37, only the light passing portion and the visually observing portion of the optical sensor are made of quartz, and the other portions are made of carbon to form a window-like light transmitting portion. It can also be configured as a member having. Similarly, the shielding device body 31 may be made of quartz only in a necessary portion and carbon in the other portion.

FIG. 2 is a schematic side view for explaining another example of the shielding device in the sintering furnace according to the present invention, in which 38 is a gap provided between the sleeve and the main body of the shielding device. In addition, other parts having the same functions as those in FIG. 1 are denoted by the same reference numerals as those in FIG. In the present embodiment, as shown in FIG. 1, a predetermined gap 38 is provided between the sleeve (upper sleeve 36, lower sleeve 37) for coping with fogging and the inner wall of the shielding device main body 31 in the disposing portion of the sleeve. Is provided.

In this embodiment, by providing a gap 38 between each of the sleeves 36 and 37 and the inner wall portion of the shielding device main body 31 as described above, the sleeves 36 and 37 can be efficiently replaced. be able to. Here, by constantly flowing an inert gas such as He inside the gap 38, unnecessary reactions in the gap 38 are suppressed to surely prevent fogging of the inner wall surface of the shielding device main body 31. You can

Further, the structure in which the gap 38 is arranged as shown in FIG. 2 is the upper sleeve 3 in the structure shown in FIG.
6 or the lower sleeve 37, and the gap 38 may be disposed only on the upper side or the lower side of the valve body 32.

[0022]

As is apparent from the above description, according to the present invention, in the sintering furnace for dehydrating / sintering the glass particulate deposit body (soot body) to obtain transparent vitrification, In order to cope with the occurrence of fogging in the shielding device for blocking the storage portion of the glass particulate deposit, the sintering device is configured so that the fogging portion can be easily replaced. The work of disassembling the furnace and replacing the entire shielding device is unnecessary, and thereby the clouded portion can be regenerated without significantly lowering the operation rate of the sintering furnace.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an internal configuration example of a shielding device in a sintering furnace according to the present invention.

FIG. 2 is a schematic view showing another example of the internal configuration of the shielding device in the sintering furnace according to the present invention.

FIG. 3 is a schematic configuration diagram for explaining a dehydration / sintering operation of a sintering furnace for dehydrating / sintering a glass particle deposit body (soot body) to obtain transparent vitrification.

4 is a schematic side view showing the internal structure of a shielding device (gate valve) in the sintering furnace shown in FIG.

[Explanation of symbols]

10 ... Sintering furnace, 11 ... Carbon furnace core tube, 12 ... Quartz furnace core tube, 30 ... Shielding device, 31 ... Shielding device main body part, 31
a ... Flange portion, 31b ... Valve storage case, 32 ... Valve body,
33 ... Valve support member, 34 ... Light source, 35 ... Optical sensor, 3
6 ... Upper sleeve, 37 ... Lower sleeve, 38 ... Gap.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takehiko Kito             Sumitomoden 1 Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa             Ki Industry Co., Ltd. Yokohama Works (72) Inventor Yuji Kakeda             Sumitomoden 1 Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa             Ki Industry Co., Ltd. Yokohama Works F-term (reference) 4G014 AH21                 4G021 CA12

Claims (5)

[Claims] 1. A glass fine particle deposit housed inside the furnace core tube, comprising: a furnace core tube for accommodating a glass particle deposit body in which glass fine particles are deposited; and a shielding device for shielding the furnace core tube. A sintering furnace for heating and dehydrating / sintering a body, wherein the shielding device has a valve body for shielding the furnace core tube, and constitutes a part of an inner wall of the shielding device. A sintering furnace characterized in that the members to be replaced are replaceable. 2. The sintering furnace according to claim 1, wherein in the shielding device, the members are provided on an upper portion and a lower portion of the valve body, respectively. 3. The sintering furnace according to claim 1, wherein the member has a sleeve shape. 4. The member and a part of the shielding device are made of a material capable of transmitting light in a predetermined wavelength range, and the sintering furnace is configured to shield the shielding device from outside the shielding device via the member. A light source that emits light toward the inside of the device, and an optical sensor that faces the light source through the shielding device and receives the emitted light from the light source, and the shielding device is based on a detection result of the optical sensor. The sintering furnace according to any one of claims 1 to 3, wherein the presence or absence of the glass particulate deposit in the interior is detected. 5. The replaceable member is arranged so that a gap is formed at least at a part between the replaceable member and the main body of the shielding device to which the member is attached, and the sintering furnace is provided with respect to the gap. The sintering furnace according to any one of claims 1 to 4, further comprising means for flowing an inert gas.