KR100737596B1 - Soot removing apparatus for mcvd-process and soot removing method using the same - Google Patents

Abstract

A soot removing device for an MCVD(Modified Chemical Vapor Deposition) process and a method thereof are provided to smoothly discharge soot by removing soot particles that are not deposited in a silica tube through a soot removing rod and also removing soot particles stuck to the front end of the soot removing rod through a cleaning unit. A soot removing device for preventing silica soot discharged at a silica tube(100) from being piled up in an exhaust inner tube(110) during an MCVD process for making an optical fiber preform is composed of a soot removing rod(200) contacted to an inner wall of the inner tube; a first driving unit(300) for rotating the soot removing rod oppositely to the rotational direction of the silica tube; a second driving unit(400) moving the soot removing rod forward or backward for the inner tube by reciprocating the first driving unit; and a cleaning unit(500) removing the soot piled up in the end of the soot removing rod when the backward movement of the soot removing rod is finished.

Description

Soot removing apparatus for MCVD-process and soot removing method using the same}

The following drawings, which are attached to this specification, illustrate exemplary embodiments of the present invention, and together with the detailed description of the present invention, serve to further understand the technical spirit of the present invention. It should not be construed as limited to.

1 is a cross-sectional view showing a manufacturing process of an optical fiber base material using a modified chemical vapor deposition (MCVD) according to the prior art.

2A and 2B are cross-sectional views showing the configuration of a soot removal apparatus for MCVD according to the prior art.

Figure 3 is a schematic cross-sectional view showing the configuration of the soot removal apparatus for MCVD process according to a preferred embodiment of the present invention.

4 to 7 are cross-sectional views sequentially showing the operation of the soot removal apparatus for MCVD process according to a preferred embodiment of the present invention.

<Description of Major Reference Marks in Drawing>

100. Quartz tube 110. Inner tube 200 Suitcase rod

300. First drive means 400 Second drive means 500 Cleaning means

The present invention relates to a soot removing apparatus used in the manufacture of an optical fiber base material, and more particularly, to a modified chemical vapor deposition (MCVD) process for smoothing the discharge of undeposited soot during the preparation of an optical fiber base material using a crystal chemical vapor deposition method. It relates to a soot removal device.

Representative process technologies for manufacturing optical fiber base materials by vapor deposition generally include Vapor-Phase Axial Deposition (VAD), Outside Vapor Deposition (OVD), and Modified Chemical Vapor Deposition (MCVD). Can be mentioned.

Among them, the MCVD method is a method of sequentially forming a clad and a core by internal deposition. More specifically, a carrier gas is injected into a hollow tube together with a reactor gas, and a base material is heated using a heat source to form the inside of the base material. In the optical oxidation matrix manufacturing method to form a clad and core by repeatedly performing the deposition due to the thermal oxidation in the layer unit.

1 schematically shows a deposition process of a clad / core, which is a main process of the MCVD method.

1, the MCVD method is rotary quartz tube (1) into the SiCl _4, GeCl _4, PoCl ₃ such as the reaction gas (See a solid line arrow), the injection with an oxygen box and, at the same time, heat gel (Thermophoresis) in which The quartz tube 1 is heated by repeatedly reciprocating the heat source 3 along the longitudinal direction (axial direction) of the quartz tube 1 so that the reactant 2 (suit) is deposited on the inner wall of the tube. The deposition process proceeds in such a way that the deposition layer 4 is formed. Here, the reaction in which the soot is produced is represented as follows.

SiCl ₄ (g) ₊ O ₂ (g) → SiO ₂ (s) + 2Cl ₂ (g)

GeCl ₄ (g) + O ₂ (g) → GeO ₂ (s) + 2Cl ₂ (g)

The MCVD method has the advantage of relatively less internal contamination due to external foreign matters compared to the external deposition method, whereas silica soot not deposited inside the quartz tube during the deposition process accumulates in the exhaust tube, resulting in tube clogging. There is a vulnerability that can occur.

In the actual MCVD process, silica particles are deposited in the quartz tube by thermal phenomena only 40-50%, and the remaining amount of the remaining reactive oxides which are not deposited are discharged as they are in the soot discharge stage or the quartz tube. It is laminated on the inner wall of the elongated exhaust tube, that is, the inner tube.

When the silica soot is laminated on the inner wall of the inner tube, it is difficult to control the outer diameter or the internal pressure of the produced base material because the exhaust is not made smoothly. Therefore, it is necessary to stop the manufacture of the optical fiber base material and to remove the silica soot deposited on the inner wall of the inner tube. There is a problem.

As an alternative to the soot lamination problem as described above, a method of removing a soot widely used in the related art may include a method of scraping an inner wall of an inner tube using a soot removing rod as shown in FIGS. 2A and 2B.

2A and 2B, the conventional soot removal apparatus is connected to the soot removal rod 20 installed through the soot removal rod 20 installed to contact the inner wall of the inner tube 10 and the coupler to remove the soot. It is provided with a motor 30 for providing a rotational force to the rod (20).

Referring to the operation of the soot removal device of the above configuration is as follows. That is, the carrier gas is injected into the quartz tube 11 having the hollow together with the reactor body, and the soot 40 is deposited inside the quartz tube 11 by heating the quartz tube 11 using the heat source 50. And sintered. At this time, the heat source 50 reciprocates along the longitudinal direction of the quartz tube 11 at the connection point between the quartz tube 11 and the exhaust tube 12.

On the other hand, the soot not deposited in the quartz tube 11 is discharged along the inner tube 10. Since the inlet temperature of the inner tube 10 is relatively lower than that of the quartz tube 11, the soot may be formed by thermophoresis. It is deposited on the inlet side of the inner tube 10. In order to remove the soot deposited in the related art, the inner wall of the inner tube 10 is mechanically scraped while the soot removing rod 20 is continuously rotated in a direction opposite to the rotation direction of the inner tube 10. ) The soot 40 stacked on the inner wall was removed.

However, the gases and soots passing through the exhaust tube 12 maintain a high temperature and the tip 13 of the soot removal rod is relatively low so that there is a high temperature difference between the soot and the soot stripping rod 13. As shown in FIG. 2B, the soot is easily attached to the end 13 of the soot removing rod and the inner tube 10 is rather formed due to the soot deposited on the end 13 of the soot removing rod when the soot is not efficiently removed. There was a clogging issue.

The present invention has been made to solve the above problems, in the manufacture of the optical fiber base material by a crystal chemical vapor deposition method, the discharged soot is laminated to the end of the soot removal rod to block the exhaust tube or grow the optical fiber base material due to the soot mass It is an object of the present invention to provide a soot removing apparatus and soot removing method capable of preventing contamination in a tube.

In order to solve the above problems, the present inventors inject gas from the gas injection means disposed at the end of the soot removal rod to remove the soot while rotating the soot removal rod and at the same time the gas is injected from the gas injection means to the end of the soot removal rod The company developed a suit removal apparatus that can prevent the suit from being attached to the suit, and filed a patent application (2005-0124017) on December 15, 2005. The inventors and others have subsequently developed a soot removal apparatus suitable for producing an optical fiber base material while efficiently removing the soot and completed the present invention.

That is, the soot removing apparatus according to the present invention is a device for preventing the silica soot discharged from the quartz tube from being laminated on the exhaust inner tube during the MCVD process for fabricating the optical fiber base material, and removing the soot installed in contact with the inner wall of the inner tube. A first driving means for rotating the soot removing rod in a direction opposite to the rotation direction of the quartz tube, a second driving means for reciprocating the first driving means to advance or retract the soot removing rod with respect to the inner tube; And cleaning means for removing the soot deposited at the tip of the soot removal rod upon completion of the retraction of the soot removal rod.

Preferably, the second drive means comprises a hydraulic cylinder, a transfer rail and a shelf, the first drive means is mounted to the transfer rail, and the shaft of the hydraulic cylinder is coupled to the first drive means, and the hydraulic One driving means is reciprocated on the transfer rail to provide translational force to advance or retract the soot removal rod relative to the inner tube.

On the other hand, the soot removal method according to the present invention uses an exhaust tube bonded to a quartz tube and an inner tube installed therein, and a removal apparatus having a soot removal rod and cleaning means inserted into the inner tube to scrape off the silica soot. A method of removing a soot, comprising: rotating a soot removal rod to scrape the soot laminated to the inner tube inner wall, and retreating the soot removal rod from the inner tube while the deposition heat source returns to the process starting point, Approaching the cleaning means to the tip of the soot removal rod, operating the cleaning means to remove the silica soot adhered to the front end of the soot removal rod, and returning the soot removal rod to its original position before the deposition heat source is transferred in the process direction. Advancing to.

Preferably, the soot removal rod is rotated at a speed of 10 to 60 rpm, and is also retracted or advanced at a speed of 100 mm / min to 6000 mm / min.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

3 is a view schematically showing the configuration of a soot removal apparatus for an MCVD process according to a preferred embodiment of the present invention.

Referring to FIG. 3, the present invention includes an exhaust tube 100a extending from the quartz tube 100, an inner tube 110 installed inside the exhaust tube 100a, and a soot removal rod installed inside the inner tube 110. 200, the first driving means 300 for providing a rotational motion force to the soot removal rod 200, the second driving means 400 for providing a translational movement force to the soot removal rod 200, and the soot removal rod And cleaning means 500 for removing the silica soot 700 attached to the end of the 200.

The soot removal rod 200 is in contact with the inner wall of the inner tube 110 and is installed in the inner tube 110 so that its tip is located approximately at the inlet 700 of the soot 700 of the inner tube 110.

The soot removal rod 200 has a circular cross section perpendicular to the axial direction, but the present invention is not limited thereto, and the soot removing rod 200 may have an elliptical shape or a polygonal shape. When the cross section of the soot removal rod 200 is circular, its diameter is preferably 7 to 10 mm.

In addition, the soot removal rod 200 is made of a metal material is more advantageous than other materials, such as plastic in terms of strength and heat resistance. Preferably, the soot removal rod 200 is made of stainless steel (SUS).

Additionally, the soot removal rod 200 is smoothly surface treated to prevent the soot 700 from sticking to its surface.

The first driving means 300 is connected to the rear end of the soot removal rod 200 via the coupler 310 and provides a rotational motion force opposite to the rotation direction of the quartz tube 100. As the first driving means, it is preferable that a motor is used, but is not limited thereto. Of course, all other rotary power generators may be used.

The second driving means 400 is equipped with the first driving means 300 and moves the first driving means 300 and the soot removing rod 200 to the left and right. Specifically, the second driving means 400 retreats or advances the soot removal rod 200 from the inner tube 110. Since the soot removing rod 200 is connected to the first driving means 300, the first driving means 300 is mounted on the second driving means 400 to perform a translational movement, and thus the soot removing rod 200 is provided. The inner tube 110 is withdrawn or drawn into the inner tube 110.

For example, the second driving means 400 includes a hydraulic cylinder (not shown), a transfer rail (not shown) and a shelf (not shown). The first driving means 300 is mounted on the transfer rail, and the shaft of the hydraulic cylinder is coupled to the first driving means 300 so that the first driving means 300 moves forward or backward on the transfer rail by hydraulic pressure. However, the present invention is not limited thereto.

The cleaning means 500 removes the silica soot 700 mounted on the shelf of the second driving means 400 and attached to the end 210 of the soot removal rod 200. Here, the cleaning means 500 is fixedly disposed ahead of the first driving means 300 in the advancing direction of the soot removal rod 200. Therefore, when the soot removing rod 200 is retracted from the inner tube 110, the end 210 thereof is disposed in a straight line in a direction perpendicular to the traveling direction of the cleaning means 500 and the soot removing rod 200. do. The cleaning means 500 removes the silica soot in contact with the end of the soot removing rod 200 in the form of a heat resistant brush and attached to the end of the soot removing rod 200 in a physical manner. Although not shown in the drawing, the clickable means 500 is connected to a separate driving means and is translated in the up and down directions with respect to the soot removal rod 200.

Next, a method of removing the soot using the soot removal apparatus according to a preferred embodiment of the present invention will be described.

4 to 7 are diagrams sequentially showing the soot removal process according to the present invention.

4 to 7, first, the soot forming gas and oxygen mixed gas are introduced into the quartz tube 100 while the quartz tube 100 is rotated, and the quartz tube 100 is used by using the heat source 600. Heat).

The soot forming gas introduced into the quartz tube 100 (see arrow A in FIG. 4) is oxidized by heat conducted from the surface of the quartz tube 100 to generate a soot, which is in the quartz tube 100. Moves to a relatively low temperature region and is deposited on the inner wall of the quartz tube 100 by thermophoresis.

Clad soot particles deposited at least one or more layers on the inner wall of the quartz tube 100 are subsequently sintered and vitrified by an approaching heat source to form a sintered layer.

This soot deposition and sintering process is repeated continuously until the desired clad and core have the desired thickness.

At this time, the soot not deposited in the quartz tube 100 is transferred to the exhaust tube 100a. Since the inner tube 110 is provided in the exhaust tube 100a, the silica soot 700 transferred to the exhaust tube 100a is stacked on the inlet side of the inner tube 110.

In order to remove the silica soot 700 stacked in the inner tube 110, as shown in FIG. 4, the soot removing rod 200 is operated by operating the first driving means 300. Rotate in the opposite direction of rotation. Then, the soot removal rod 200 mechanically scratches the inner wall of the inner tube 110 to remove the stacked soot 700. At this time, the rotation speed of the soot removal rod 200 is preferably 10 to 60rpm.

Meanwhile, a part of the silica soot 700 stacked on the inlet side of the inner tube 110 is removed from the inner tube 110 and discharged out of the exhaust tube 100a, but a part is attached to the front end of the soot removing rod 200. (See B of FIG. 4).

Next, referring to FIG. 5, when the heat source moves from the end of deposition of the quartz tube 100 to the start of deposition (see arrow a in FIG. 5), that is, the quartz tube 100 and the exhaust tube 100a. When away from the junction of), the soot removal rod 200 is retracted by the second driving means 400 and withdrawn from the inner tube 110. Here, the soot removal rod 200 is preferably moved at a speed of 100mm / min ~ 6000mm / min.

Then, as shown in FIG. 6, the cleaning means 500 is raised to the end point of the soot removal rod 200.

The shear of the soot removal rod 200 is in contact with the raised cleaning means 500 (see FIG. 6C), and the silica soot adhered to the front end of the soot removal rod 200 by the rotation of the cleaning means 500 ( 700) are removed.

When the soot removal operation is completed by the method described above, as shown in FIG. 7, the cleaning means 500 before the heat source starts to move again from the deposition start point toward the deposition end point (see arrow b in FIG. 7). Lower to the original position, the second driving means 400 is operated so that the tip of the soot removal rod 200 comes to the inlet of the inner tube (110). At this time, the soot removal rod 200 is preferably moved at a speed of 100mm / min ~ 6000mm / min. Then, when the heat source 600 starts to be transferred in the process progress direction and the soot deposition and sintering process is started, the first driving means 300 is operated to start the soot removal operation.

The soot removal operation described above performed in the process of returning the heat source 600 to the starting point of the process is repeated until the manufacture of the optical fiber base material is completed.

Although the invention has been described above by means of limited embodiments and drawings, the invention is not limited thereto and will be described below by the person skilled in the art and the technical spirit of the invention. Various modifications and variations are possible without departing from the scope of the appended claims.

According to the present invention, not only the soot particles that are not deposited in the quartz tube during the preparation of the optical fiber base material are removed through the soot removing rod, but also by removing the soot particles attached to the front end of the soot removing rod using a separate cleaning means, It can make the discharge smooth. Therefore, it is possible to improve the yield and quality of the optical fiber base material manufacturing using the MCVD process.

In addition, when manufacturing a large-diameter optical fiber base material, by increasing the discharge of the soot particles increased due to the reaction gas flowing in a large amount to improve the manufacturing stability to improve the large-diameter optical fiber base material manufacturing yield as well as cost reduction effect.

Claims (9)

An apparatus for preventing silica soot emitted from a quartz tube from being deposited on an exhaust inner tube during an MCVD process for manufacturing an optical fiber base material, A soot removing rod installed to contact the inner wall of the inner tube; First driving means for rotating the soot removal rod in a direction opposite to the rotation direction of the quartz tube; Second driving means for reciprocating the first driving means to advance or retract the soot removing rod with respect to the inner tube; And And a cleaning means for removing the soot deposited on the tip of the soot removal rod upon completion of the retreat of the soot removal rod. The method of claim 1, The second driving means includes a hydraulic cylinder, a transfer rail and a shelf, The first driving means is mounted on the transfer rail, and the shaft of the hydraulic cylinder is coupled to the first driving means so that the first driving means is reciprocated on the transfer rail by hydraulic pressure so that the soot removing rod is moved against the inner tube. A soot removal device for providing forward or backward translational motion. The method of claim 1, And the cleaning means comprises driving means for providing translational movement force in the up and down directions with respect to the soot removal rod. The method of claim 1, And the cleaning means is a brush having heat resistance. A method of removing a soot using a removal apparatus having an exhaust tube bonded to a quartz tube and an inner tube provided therein, and a soot removing rod and cleaning means inserted into the inner tube to scrape the silica soot, (a) rotating the soot removal rod to scrape off the soot laminated to the inner wall of the inner tube; (b) retracting the soot removal rods from the inner tube and approaching the cleaning means to the tip of the soot removal rods while the deposition heat source returns to the process starting point; (c) operating the cleaning means to remove silica soot adhered to the front end of the soot removal rod; And and (d) advancing the soot removing rod to its original position before the deposition heat source is transferred in the process progress direction. The method of claim 5, In the step (a), the soot removal rods, characterized in that for rotating at a speed of 10 to 60rpm. The method of claim 5, In the step (b) or (d), the soot removal rod retreat or advance at a rate of 100mm / min ~ 6000mm / min. The method of claim 5, In the step (c), the soot removing method, characterized in that the cleaning means by using a cleaning method to scrape the silica soot attached to the front end of the soot removal rod by a physical method. The method of claim 5, In the step (b), the cleaning means is a soot removal method characterized in that the translation movement in the up, down direction with respect to the soot removal rod.

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