JPH10120428A - Apparatus for regulating pressure of dehydration sintering furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus, capable of carrying out the nearly accurate pressure regulation and excellent in aspects of durability. SOLUTION: This apparatus for regulating the pressure of a dehydration sintering furnace 10 comprises a pressure regulating chamber 2 connected through a communicating tube 1 to the sintering furnace 10 for carrying out the dehydration and sintering of a soot preform and making a gas in the sintering furnace 10 flow thereinto, a pressure sensing means 3, provided in a part of the communicating tube 1 and used for sensing the pressure of the gas passing through the communicating tube 1 and a soleniod valve 4 for suitably discharging a part of the gas to the outside when the pressure of the gas flowing from the sintering furnace 10 into the pressure regulating chamber 2 exceeds a prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dehydration and sintering furnace for dehydrating and sintering a preform (soot preform) used for manufacturing optical fibers, and more particularly to adjusting the internal pressure of the dehydration and sintering furnace to a constant value. The present invention relates to a pressure adjusting device capable of performing the pressure adjustment.

[0002]

2. Description of the Related Art As is well known, in the VAD method, which is known as one of the methods for manufacturing an optical fiber, a seed rod (quartz rod) is used.
After soot is deposited on the base material to form a base material (hereinafter referred to as a soot preform), the soot preform is dehydrated and sintered at a high temperature. A furnace is used.

As shown in FIG. 2, this sintering furnace 10 includes:
It is provided with a heater 100 for heating and shuts off the flow of air from the outside to keep it almost airtight, so that a dehydration gas such as helium gas or the like is sent into the inside from an appropriate intake port 10A. In order to perform a uniform dewatering / sintering action, the internal pressure needs to be kept almost constant.

Therefore, this sintering furnace 10 is provided with, for example, FIG.
As shown in FIG. 1, a bag-shaped air reservoir (formed of a heat-resistant material) communicated via a communication pipe 101 (hereinafter referred to as an air bag 1).
A pressure adjusting device 105 including a weight 104 pivotally supported by an arm 103 to apply a weight to the air bag 102 from above is known. Here, reference numeral 11 denotes a soot preform, and reference numeral 12 denotes a chuck for holding the seed rod 11A.

In this pressure adjusting device, the weight 104
Is constantly acting on the air bladder 102, whereby the air bladder 102 is maintained at a substantially constant internal pressure. When the internal pressure of the sintering furnace 100 increases (for example, a pressure difference of 10 to 20 mmH ₂ O or more), the air bag 102
, A dehydration gas or the like flows in from the internal pressure difference. Then, when the pressure difference with the sintering furnace 10 becomes substantially zero, the pressure is balanced and the flow into the air bag 102 is stopped, and the pressure in the sintering furnace 10 returns to almost the original standard pressure. That is.

[0006]

However, in such a pressure adjusting device, since the weight of the weight acting directly on the air bag from above is used, accurate pressure adjustment and further durability and the like are not achieved. There are many problems.

[0007] In view of the above circumstances, the present invention can perform almost accurate pressure adjustment.
It is an object of the present invention to provide a pressure adjusting device for a dehydration sintering furnace which is excellent in durability.

[0008]

That is, the present invention relates to a pressure regulating chamber which is connected and connected to a sintering furnace for dehydrating and sintering a soot preform by a communication pipe, and into which a gas flows from the sintering furnace. A pressure detecting means provided at a part of the communication pipe for detecting a pressure of a gas passing through the communication pipe; and a gas detecting means for detecting a pressure of a gas flowing from the sintering furnace into the pressure adjusting chamber when the pressure exceeds a predetermined value. And an automatic exhaust valve for appropriately exhausting a part of the outside to the outside.

[0009]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram showing a pressure adjusting device of a dehydration sintering furnace according to the present invention. The pressure adjusting device of this embodiment includes a pressure adjusting chamber 2 connected to a dehydration sintering furnace 10 by a communication pipe 1, a pressure detector 3 provided in the communication pipe 1, and an electromagnetic valve 4 provided in the pressure adjusting chamber 2. And a control unit 5.

The communication pipe 1 is made of a suitable heat-resistant material (having a small diameter), and has an appropriate pressure detector 3 resistant to high temperatures therein. The pressure detector 3 is preferably installed near the pressure adjustment chamber 2 as much as possible in order to suppress the influence of high temperature from the dehydration sintering furnace 10.

The pressure adjusting chamber 2 is formed of an appropriate heat-resistant material and has an appropriate volume capable of absorbing pressure fluctuations, and a part thereof is provided with an exhaust port 2A. It should be noted that the pressure adjustment chamber 2 is usually set and maintained at almost the same internal pressure as the standard pressure value of the dehydration sintering furnace 10. Therefore, the electromagnetic valve 4 is attached to the exhaust port 2A, and the opening and closing operation is controlled by a control signal from the control unit 5.

The control unit 5 has an input connected to the pressure detector 3 and an output connected to the solenoid valve 4.
When a detection signal output when the pressure detector 3 exceeds a certain pressure is input, a control signal is output to the solenoid valve 4 to open the solenoid valve 4.

Therefore, according to this embodiment, when the internal pressure of the dehydration sintering furnace 10 rises and exceeds the reference pressure value (set to an appropriate value exceeding the standard pressure value), the pressure detector 3 is activated. A detection signal corresponding to the pressure value is output to the control unit 5.

Then, while this signal is being input, a predetermined control signal is output from the control unit 5 to the solenoid valve 4 to open the solenoid valve 4, and the dehydration gas and the like are discharged to the outside. When the gas is exhausted and reduced to a constant internal pressure, that is, a standard pressure value, the exhaust operation stops.

As a result, the internal pressure of the dehydration sintering furnace 10 can return to the original standard pressure value.

[0017]

As described above, according to the present invention, the pressure at which the gas flows into the sintering furnace is connected to and connected to the sintering furnace for dehydrating and sintering the soot preform by the communication pipe. A control chamber, a pressure detecting means provided in a part of the communication pipe, for detecting a pressure of a gas passing through the communication pipe, and a pressure of a gas flowing from the sintering furnace into the pressure control chamber exceeds a predetermined value. Since an automatic exhaust valve for appropriately exhausting a part of this gas to the outside is provided, the pressure value of the dehydrating gas in the communication pipe is detected by the pressure detecting means and output to the control unit as a detection signal, and the control is performed. When the section detects that the pressure exceeds a predetermined pressure, it outputs a control signal to open the automatic exhaust valve and appropriately discharge high-pressure gas from the pressure adjustment chamber. The pressure can be adjusted to almost accurate pressure, and this pressure adjustment chamber Preferable in terms of durability because there is no need to use the air bag, such as the come.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a pressure adjusting device according to the present invention.

FIG. 2 is a schematic configuration diagram showing a conventional pressure adjusting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Communication pipe 2 Pressure adjustment chamber 3 Pressure detector 4 Solenoid valve 5 Control part 10 Dehydration sintering path 11 Soot preform

Claims (1)

[Claims] A sintering furnace (10) for dehydrating and sintering a soot preform (11) is connected and connected with a sintering furnace (1) by a communication pipe (1), and a pressure adjustment for gas to flow from the sintering furnace (10). A chamber (2) and a part of the communication pipe (1), wherein the communication pipe (1) is provided.
Pressure detection means (3) for detecting the pressure of gas passing through
And an automatic exhaust valve (4) for appropriately exhausting part of the gas to the outside when the pressure of the gas flowing from the sintering furnace (10) into the pressure adjusting chamber (2) exceeds a predetermined value. A pressure adjusting device for a dehydration sintering furnace.