JPH11199238A - Glass particle deposition equipment - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To efficiently deposit glass particles on a peripheral side surface of a target rod at a high speed. SOLUTION: When a glass fine particle flow 22 from a glass fine particle generation burner 21 is sprayed on a side surface of a target rod 11 to form a glass fine particle deposition layer 12 around the target rod 11, the weight of the target rod 11 is measured by weight. The measured value output is sent to the controller 42, the motor 43 is rotated according to the deposition weight, and the rotating shafts 37, 38 are rotated in the opposite directions via the rotation driving mechanism 39, and the glass fine particle deposition is performed. When the layer 12 becomes larger as shown by the dotted line, the front halves 35 and 36 of the upper and lower covers 31 and 32 are rotated and spread as shown by the dotted line accordingly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass particle deposition apparatus for generating and depositing glass particles by utilizing a gas phase reaction process, and more particularly to depositing glass particles around a round target rod. The present invention relates to a so-called external device for depositing glass fine particles.

[0002]

2. Description of the Related Art In order to increase the thickness of a cladding layer of a glass base material for an optical fiber, a core at a central portion and a part of the cladding are formed by a VAD method and are made vitrified and then transparentized by an external device. 2. Description of the Related Art A glass fine particle layer serving as a clad is deposited around a glass rod. The secondary glass particle deposition process in this external device is a chamber evacuated by an exhaust gas treatment facility (referred to as a deposition chamber) for the purpose of stabilizing the flow of glass particles and preventing adhesion of dust and the like.
Is done within.

[0003] That is, as shown in FIG. 3, a round bar-shaped transparent glass rod is held as a target rod 11 so as to rotate, and a burner 21 is directed toward the side of the target rod 11.
Place. Fuel gas containing hydrogen gas and oxygen gas is fed into the burner 21 to generate an oxyhydrogen flame. Fine particles of silicon dioxide (glass fine particles) are generated by introducing a glass material gas such as silicon tetrachloride into the flame and causing a hydrolysis reaction. The glass fine particle flow 22 is sprayed on the side surface of the target rod 11 to deposit glass fine particles on the side surface. The target rod 11 is rotating, and the burner 21 reciprocates in the axial direction of the target rod 11 as shown by an arrow, whereby the glass fine particle deposition layer 12 grows in a columnar shape on the side surface of the target rod 11. Will be.

[0004] The deposition chamber 30 includes covers 31 and 32 forming two side walls (upper and lower side walls in the figure) so as to sandwich the target rod 11 from the side. In addition,
Sidewalls are also provided near both ends of the target rod 11, but are omitted in the figure. The covers 31 and 32 cover the target rod 11 so as to have openings 33 and 34 on the front side and the back side, respectively. These openings 33, 34
Are provided at positions facing each other with the target rod 11 interposed therebetween.

An opening 33 on the front side is an opening for introducing the glass fine particle flow 22 into the chamber 30, and the chamber 3 for the glass fine particle flow 22 ejected from the reciprocating burner 21.
The target rod 11 is long in the axial direction of the target rod 11 so as not to hinder the inflow of the target rod 11 into the inside (and the reciprocating movement of the burner 21). The opening 34 on the back is an exhaust opening, and is connected to a suction pipe (not shown) connected to an exhaust gas treatment facility.

[0006]

However, the conventional apparatus for depositing fine glass particles (external device) has a problem that the deposition rate of glass fine particles and the yield of raw materials are not so good.

At the start of deposition, there is no deposited layer around the target rod, but at the end of deposition, a deposited layer having a predetermined thickness is formed. As described above, since the outer diameter of the glass fine particle deposition layer gradually increases, the velocity of the airflow around the glass fine particle deposition layer greatly changes between the initial stage and the final stage of the deposition. The deposition rate and raw material yield of the glass particles are affected by the exhaust air volume of the deposition chamber and the airflow around the deposited glass particle deposition layer. This means that the airflow is not always optimal. In particular, when the speed of the airflow around the deposition layer is low at the beginning of the deposition, the contact area between the flow of the glass particles and the target surface becomes small, and the deposition rate becomes low. As for this deposition rate, the deposition rate at the beginning of the deposition was the rate-determining stage.

[0008] In view of the above, it is an object of the present invention to provide a glass particle deposition apparatus capable of improving the deposition rate of glass particles and improving the yield of raw materials.

[0009]

In order to achieve the above object, a burner for producing glass fine particles which is moved in the axial direction of the target rod while spraying the glass fine particles on the side surface of a rotating round rod-shaped target rod, The deposition chamber covering the target rod of the target chamber, and both side walls of the deposition chamber covering both sides of the target rod sandwiching the target rod from the side, in a direction away from the target rod according to the growth of the glass fine particle deposition layer. And a moving mechanism.

[0010] In the deposition chamber, both side walls covering the both sides of the target rod so as to sandwich the target rod from the side, and the target rod is deposited on the side surface of the target rod according to the growth of the glass fine particle deposition layer. Moved away from Therefore, when the outer diameter of the glass fine particle deposition layer gradually increases, the gap between the target rod and both side walls increases accordingly. A predetermined distance can be maintained between the surface of the layer and both side walls, so that the airflow around the glass particle deposition layer can be stabilized and the speed of the airflow can be increased. As a result, the speed of the airflow around the deposition layer is low at the beginning of the deposition and the deposition rate is not low, so that the deposition rate can be improved throughout the deposition process and the material yield can be increased.

[0011]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an apparatus for depositing glass fine particles (an external device) according to the present invention.
FIG. 4 is a schematic cross-sectional view of a cross section taken along a plane perpendicular to the axis of the target rod and viewed from an end of the target rod. In this figure, the portions corresponding to FIG. 3 are denoted by the corresponding numbers. The round target bar 11 is held perpendicularly to the plane of the drawing and rotated. A burner 21 for generating glass fine particles is arranged toward a side surface of the target rod 11, and a glass fine particle flow 22 from the burner 21 is supplied to the target rod 11.
The target rod 11 can be reciprocated in the axial direction (a direction perpendicular to the paper surface) while being further sprayed. As a result, a glass fine particle deposition layer 12 is formed on the side surface of the target rod 11.

The deposition chamber 30 covers the target rod 11 and the glass particle deposition layer 12, and has a front opening 33 and a back opening 34. The glass fine particle flow 22 ejected from the burner 21 is introduced from the front opening 33, and a suction pipe from an exhaust gas treatment facility (not shown) is connected to the rear opening 34 and exhausted.
As a result, the glass fine particle flow 22 ejected from the burner 21 changes the target rod 11 and the glass fine particle deposition layer 12.
, A flow of air toward the opening 34 on the back surface is further formed.

The upper cover 3 of the deposition chamber 30
The first half 35 is attached to a rotating shaft 37 so as to rotate about the shaft 37. Similarly, the front half 36 of the lower surface cover 32 is attached to a rotating shaft 38 so as to rotate around the rotating shaft 38. These rotating shafts 37 and 38 are simultaneously rotated in opposite directions by a rotation driving mechanism 39 that transmits the rotating force of the motor 43. This rotation drive mechanism 39
Although shown here as being constituted by a gear mechanism, it can be constituted by an appropriate mechanical mechanism such as a belt pulley mechanism or a cam link mechanism.

The weight of the target rod 11 to which the glass fine particle deposition layer 12 has adhered is measured by a weight measuring device 41. This can be done, for example, by measuring the weight of a holder (not shown) that holds the target rod 11 at both ends. The measured weight value output thus measured is sent to the controller 42, and the motor 43
Control.

By measuring the weight of the target rod 11 in advance and subtracting it from the measured weight, the deposited weight of the glass fine particles can be determined. The opening width is controlled according to the deposition weight as shown in FIG. Here, the opening width is the width of the front opening 33 (upper and lower opening widths). According to the characteristics shown in FIG. 2, the opening width is set to 100 mm at the beginning of the deposition, and the opening width is gradually widened when the deposition weight exceeds 1 kg and 300 m when the deposition weight becomes 3 kg.
m. Here, the target rod 11
Has an outer diameter of 15 mm, and the outer diameter of the glass particle deposition layer 12 when the deposition weight reaches 6 kg is 120 mm.

That is, at the beginning of the deposition,
The front halves 35, 36 of the lower covers 31, 32 are positioned as shown by solid lines in FIG. When the deposited weight exceeds 1 kg, the controller 42 rotates the motor 43 to rotate the rotating shafts 37 and 38 via the rotation driving mechanism 39, and the upper and lower portions are moved in the direction in which the front opening 33 is opened as indicated by the dotted line. The first half 35, 36 of the lower cover 31, 32 is rotated.

Therefore, when the thickness of the glass fine particle deposition layer 12 formed on the side surface of the target rod 11 is small,
The front opening 33 is in a more closed state, and the upper and lower covers 31, 32 (35, 36) are separated from the target rod 11.
Although the distance to the inner surface is short, when the deposition proceeds and the glass fine particle deposition layer 12 becomes thicker as indicated by the dotted line, the upper / lower cover 31 opens the front opening 33 accordingly. , 32 rotate, and the upper and lower covers 31, 32 move from the target rod 11.
The distance to the inner surface of (35, 36) increases. As a result, the surface of the glass particle deposition layer 12 and the upper and lower cover 3
The gap between the inner surfaces of the first and second (35, 36) is the glass fine particle deposition layer 12 from the initial stage of the deposition to the end of the deposition.
Irrespective of the change in the thickness of the glass fine particles, the air flow becomes constant to a certain extent (for example, about 90 mm), and the state of the air flow around the glass fine particle deposition layer 12 can always be close to the optimum state.

As described above, during the deposition in which the thickness of the glass particle deposition layer 12 changes, the glass particle deposition layer 12
Can improve the state of the airflow around it, so that the deposition rate can be improved and the yield of the raw material can be increased.
For example, in the experimental example, the deposition rate is conventionally about 10 g / mi.
n was increased to about 12 g / min, and the raw material yield was increased by about 30%. Further, even when the deposition progresses and the glass fine particle deposition layer 12 becomes thicker, the surface of the glass fine particle deposition layer 12 and the upper / lower cover 31, 32 (35, 3
Since the gap between the inner surface and the inner surface of (6) can be maintained at a certain distance or more, the outermost glass particle deposition layer
When 2 is made into a transparent glass to form a clad layer, the number of bubbles generated in the clad layer can be reduced.

It should be noted that the above describes one embodiment of the present invention, and it goes without saying that the present invention is not intended to be limited to this description. For example, while the distance from the target 11 is changed by rotating the first half 35, 36 of the upper / lower cover 31, 32, in the deposition chamber, both side walls covering the both sides of the target rod so as to sandwich the target rod from the side. The portion may be any structure that can be moved in a direction away from the target rod in accordance with the growth of the glass fine particle deposition layer that grows by depositing on the side surface of the target rod. 3
It is not limited to using 2.

[0020]

As described above, according to the apparatus for depositing fine glass particles of the present invention, the deposition rate can be increased as a whole from the beginning to the end of the deposition, and the raw material yield can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention.

FIG. 2 is a graph showing control characteristics of an opening width of upper and lower covers.

FIG. 3 is a schematic perspective view showing a conventional glass particle deposition device (external device).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Target rod 12 Glass fine particle deposition layer 21 Glass fine particle generation burner 22 Glass fine particle flow 30 Deposition chamber 31 Top cover 32 Lower cover 33 Front opening 34 Back opening 35 First half of upper cover 36 First half of lower cover 37, 38 Rotation Shaft 39 Rotation drive mechanism 41 Weight measuring device 42 Controller 43 Motor

Claims (1)

[Claims] 1. A burner for generating glass fine particles which is moved in the axial direction of a target rod while spraying glass fine particles on a side surface of a rotating round rod-shaped target rod; a deposition chamber for covering the target rod; A glass comprising: a mechanism for moving both side walls of the position chamber, which cover both side surfaces of the target rod so as to sandwich the target rod from the side, in a direction away from the target rod in accordance with the growth of the glass fine particle deposition layer. Particle deposition device.