WO1989002419A1 - A device for the removal of a powdery substance accumulating in a tubular back portion of an optical fiber preform during the manufacture thereof - Google Patents

A device for the removal of a powdery substance accumulating in a tubular back portion of an optical fiber preform during the manufacture thereof Download PDF

Info

Publication number
WO1989002419A1
WO1989002419A1 PCT/FI1988/000145 FI8800145W WO8902419A1 WO 1989002419 A1 WO1989002419 A1 WO 1989002419A1 FI 8800145 W FI8800145 W FI 8800145W WO 8902419 A1 WO8902419 A1 WO 8902419A1
Authority
WO
WIPO (PCT)
Prior art keywords
screw structure
back portion
tubular back
manufacture
preform
Prior art date
Application number
PCT/FI1988/000145
Other languages
French (fr)
Inventor
Reijo Frantsi
Original Assignee
Oy Nokia Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Oy Nokia Ab filed Critical Oy Nokia Ab
Publication of WO1989002419A1 publication Critical patent/WO1989002419A1/en

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
    • C03B37/018—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD] by glass deposition on a glass substrate, e.g. by inside-, modified-, plasma-, or plasma modified- chemical vapour deposition [ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod
    • C03B37/01846—Means for after-treatment or catching of worked reactant gases

Definitions

  • This invention relates to a device for removing the powdery substance accumulating in a tubular bac portion of an optical fiber preform during the manu ⁇ facture thereof, comprising a screw structure follow ⁇ ing the inner surface of said tubular back portion.
  • the removing structure may consist of a screwlike cleaner disposed in the ex ⁇ haust tubee so as to draw excessive soot out of the tube while the tube rotates.
  • a screw struc- ture of this kind has certain drawbacks. Firstly, the soot tends to accumulate merely on the lower edge of the tube due to the force of gravity, so it cannot be moved very efficiently by means of this kind of screw. Secondly, if the screw is such that it follows the in- ner surface of the exhaust tube too accurately or if too much soot has stuck thereto, it may affect the exhaust tube mechanically, which may cause damage to the preform.
  • the object of the present invention is to pro- vide a device for the removal of a powdery substance accumulated in the tubular back portion of an optical fiber preform during the manufacture thereof, which device does not have the drawbacks of the above-men ⁇ tioned structural solutions known from the prior art and by means of which the exhaust tube can be kept open automatically and reliably.
  • the screw structure comprises a gas con- duit provided with orifices opening towards the open end of the tubular back portion.
  • dry gas such as N2 gas
  • the soot in the exhaust tube is exposed to a gas flow which tends to remove the soot out of the exhaust tube.
  • the effect of the gas flow is made even more efficient by the use of a screw structure following the inner surface of the exhaust tube and moving relative to the exhaust tube during the rotation of the preform.
  • a further im ⁇ portant advantage is that the exhaust tube now can be filled with the dry gas, which prevents moisture from entering the preform tube and, on the other hand, cools the screw structure, thus preventing the soot from melting on the surface thereof.
  • Preferred structural solutions of the screw structure include a pipe wound in the form of a spiral or a hollow fin having the shape of a spiral thread and arranged around a central axis such as a central pipe.
  • a gas conduit is automatically formed in the screw structure, and the orifices re ⁇ quired for the introduction of gas can be provided therein simply by boring.
  • the screw structure may comprise a rotating juncture which enables the screw structure to be rotated relative to the exhaust tube. If this rotation takes place in a direction reverse to the rotation of the preform it- self, the effect facilitating the emptying of the exhaust tube can be obtained at a substantially lower rate of rotation than that of the preform.
  • the figure shows an optical fiber preform 1 to be manufactured e.g. by a MCVD process, a tubular back portion 2 called an exhaust tube being attached to the preform.
  • the preform 1 and the exhaust tube 2 attached thereto are rotated in the direction shown by the arrow A in the figure usually at a rate between about 10 and about 100 revolutions per minute.
  • gases are introduced into the interior of the preform and deposited on the inner surface of the preform into a glass layer forming the cladding and core of the optical fiber preform.
  • Part of the react- ing gases and vapours enter the exhaust tube 2, where ⁇ in they tend to accumulate.
  • the exhaust tube is provided with a screw structure 3 according to the invention.
  • the screw structure comprises a pipe 3 wound in the form of a spiral and comprising orifices 5 which open towards the open end of the exhaust tube
  • the screw structure 3 is formed by a pipe, a gas conduit 4 is automatic- ally defined therewithin, into which conduit dry gas or gas mixture, such as nitrogen, is now introduced according to the invention.
  • the amount of this gas flow may be e.g. between 2 and 10 litres per minute.
  • the soot tending to accumulate in the exhaust tube 2 can be efficiently moved towards the open end of the exhaust tube 2 and removed therethrough.
  • the entrance of moisture within the preform 1 is prevented, which can also be regarded as a major advantage of the inven- tion.
  • the screw structure 3 may comprise a rotating juncture 6 which enables the screw structure to be rotated with respect to the ex ⁇ haust tube 2.
  • This rotation which takes place in the direction indicated by the arrow B shown in the fig- ure, is reverse to the direction of rotation of the preform 1.
  • the rate of rotation of the screw structure 3 in the direction of the arrow B may be rather low, such as one revolution per minute. Since the function of this rotation is to make the removal of soot more efficient, the rate of rotation can be increased if the formation of soot is abundant.
  • the screw structure 3 can be rotated by conventional means known per se, such as an electric motor through a belt, for in ⁇ stance.
  • the figure does not show any example of such a rotating structure fully obvious to one skilled in the art.
  • the figure show the gas source supplying the gas to be introduced into the gas conduit 4 of the screw structure 3.
  • Such a gas source may be e.g.

Abstract

This invention relates to a device for removing a powdery substance accumulating in a tubular back portion (2) of an optical fiber preform (1) during the manufacture thereof, comprising a screw structure (3) following the inner surface of said tubular back portion (2). In order to provide an efficient removal structure which does not affect the preform mechanically or in any other way, the screw structure (3) according to the invention comprises a gas conduit (4) provided with orifices (5) opening towards the open end of the tubular back portion (2). Preferably the structure is a pipe (3) wound in the form of a spiral.

Description

A device for the removal of a powdery substance ac¬ cumulating in a tubular back portion of an optical fiber preform during the manufacture thereof
This invention relates to a device for removing the powdery substance accumulating in a tubular bac portion of an optical fiber preform during the manu¬ facture thereof, comprising a screw structure follow¬ ing the inner surface of said tubular back portion. During the manufacture of an optical fiber pre¬ form by a MCVD process or the like by growing the pre¬ form within a quartz tube, it is of vital importance to ensure that the tubular auxiliary element attached to the back portion of the preform will not be clogged by the powdery substance (soot) accumulating therein during the process of manufacture. Conventionally, this function has been carried out fully manually by scraping off the soot accumulated in this tube called an exhaust tube at regular intervals during the anu- facture e.g. by means of a glass rod so as to prevent the clogging of the exhaust tube. The clogging of the exhaust tube would result in a pressure increase within the preform and damage the preform. Since the preform is rotated during the manufacture thereof in a so called lathe at a rate of rotation e.g. between 10 and 100 revolutions per minute, the removing structure may consist of a screwlike cleaner disposed in the ex¬ haust tubee so as to draw excessive soot out of the tube while the tube rotates. However, a screw struc- ture of this kind has certain drawbacks. Firstly, the soot tends to accumulate merely on the lower edge of the tube due to the force of gravity, so it cannot be moved very efficiently by means of this kind of screw. Secondly, if the screw is such that it follows the in- ner surface of the exhaust tube too accurately or if too much soot has stuck thereto, it may affect the exhaust tube mechanically, which may cause damage to the preform.
The object of the present invention is to pro- vide a device for the removal of a powdery substance accumulated in the tubular back portion of an optical fiber preform during the manufacture thereof, which device does not have the drawbacks of the above-men¬ tioned structural solutions known from the prior art and by means of which the exhaust tube can be kept open automatically and reliably.
The above object is achieved by means of a de¬ vice according to the invention, which is character¬ ized in that the screw structure comprises a gas con- duit provided with orifices opening towards the open end of the tubular back portion. When introducing dry gas, such as N2 gas, into the gas conduit defined in the screw structure and comprising orifices opening towards the open end of the exhaust tube, the soot in the exhaust tube is exposed to a gas flow which tends to remove the soot out of the exhaust tube. The effect of the gas flow is made even more efficient by the use of a screw structure following the inner surface of the exhaust tube and moving relative to the exhaust tube during the rotation of the preform. A further im¬ portant advantage is that the exhaust tube now can be filled with the dry gas, which prevents moisture from entering the preform tube and, on the other hand, cools the screw structure, thus preventing the soot from melting on the surface thereof.
Preferred structural solutions of the screw structure include a pipe wound in the form of a spiral or a hollow fin having the shape of a spiral thread and arranged around a central axis such as a central pipe. In this way, a gas conduit is automatically formed in the screw structure, and the orifices re¬ quired for the introduction of gas can be provided therein simply by boring.
In order to make the operation of the device according to the invention even more efficient, the screw structure may comprise a rotating juncture which enables the screw structure to be rotated relative to the exhaust tube. If this rotation takes place in a direction reverse to the rotation of the preform it- self, the effect facilitating the emptying of the exhaust tube can be obtained at a substantially lower rate of rotation than that of the preform.
In the following the device according to the invention will be described in more detail with re- ference to the attached drawing, whose figure illus¬ trates the general structure and operational principle of the device according to the invention.
The figure shows an optical fiber preform 1 to be manufactured e.g. by a MCVD process, a tubular back portion 2 called an exhaust tube being attached to the preform. During the manufacture of the preform 1, the preform 1 and the exhaust tube 2 attached thereto are rotated in the direction shown by the arrow A in the figure usually at a rate between about 10 and about 100 revolutions per minute. During the process of manufacture, gases are introduced into the interior of the preform and deposited on the inner surface of the preform into a glass layer forming the cladding and core of the optical fiber preform. Part of the react- ing gases and vapours enter the exhaust tube 2, where¬ in they tend to accumulate. In order to keep it open, the exhaust tube is provided with a screw structure 3 according to the invention. In the embodiment shown in the figure, the screw structure comprises a pipe 3 wound in the form of a spiral and comprising orifices 5 which open towards the open end of the exhaust tube
2 and which are disposed particularly in the end por¬ tion adjacent to the preform 1. As the screw structure
3 is formed by a pipe, a gas conduit 4 is automatic- ally defined therewithin, into which conduit dry gas or gas mixture, such as nitrogen, is now introduced according to the invention. The amount of this gas flow may be e.g. between 2 and 10 litres per minute. By means of the introduction of gas, the soot tending to accumulate in the exhaust tube 2 can be efficiently moved towards the open end of the exhaust tube 2 and removed therethrough. Furthermore, the entrance of moisture within the preform 1 is prevented, which can also be regarded as a major advantage of the inven- tion. As appears from the figure, the screw structure 3 may comprise a rotating juncture 6 which enables the screw structure to be rotated with respect to the ex¬ haust tube 2. This rotation, which takes place in the direction indicated by the arrow B shown in the fig- ure, is reverse to the direction of rotation of the preform 1. The rate of rotation of the screw structure 3 in the direction of the arrow B may be rather low, such as one revolution per minute. Since the function of this rotation is to make the removal of soot more efficient, the rate of rotation can be increased if the formation of soot is abundant. The screw structure 3 can be rotated by conventional means known per se, such as an electric motor through a belt, for in¬ stance. The figure does not show any example of such a rotating structure fully obvious to one skilled in the art. Nor does the figure show the gas source supplying the gas to be introduced into the gas conduit 4 of the screw structure 3. Such a gas source may be e.g. a gas bottle filled with pressurized gas and provided with suitable valves. The device according to the invention has been described above only on the basis of one exemplifying embodiment, and it is to be understood that many structural modifications can be made therein without, however, deviating from the basic principles of the invention, that is, from the gas flow created by means of a dry gas and a relative rotational movement be¬ tween the soot removal device and the preform.

Claims

Claims t
1. A device for removing a powdery substance accumulating in a tubular back portion (2) of an opti- cal fiber preform (1) during the manufacture thereof, comprising a screw structure (3) following the inner surface of said tubular back portion (2), c h a r a c¬ t e r i z e d in that the screw structure (3) com¬ prises a gas conduit (4) provided with orifices (5) opening towards the open end of the tubular back por¬ tion (2) .
2. A device according to claim 1, c h a r a c¬ t e r i z e d in that the screw structure is a pipe (3) wound in the form of a spiral.
3. A device according to clair.ι 1, c h a r a c¬ t e r i z e d in that the screw structure comprises a hollow fiή having the shape of a spiral thread and ar¬ ranged around a central axis.
4. A device according to the claims 1, 2 or 3, c h a r a c t e r i z e d in that the screw structure (3) comprises a rotating juncture (6) for enabling the screw structure (3) to be rotated.
PCT/FI1988/000145 1987-09-11 1988-09-12 A device for the removal of a powdery substance accumulating in a tubular back portion of an optical fiber preform during the manufacture thereof WO1989002419A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI873952 1987-09-11
FI873952A FI78891C (en) 1987-09-11 1987-09-11 Apparatus for removing powdery material collected in the tubular rear part in the manufacture of an optical fiber blank

Publications (1)

Publication Number Publication Date
WO1989002419A1 true WO1989002419A1 (en) 1989-03-23

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1988/000145 WO1989002419A1 (en) 1987-09-11 1988-09-12 A device for the removal of a powdery substance accumulating in a tubular back portion of an optical fiber preform during the manufacture thereof

Country Status (2)

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FI (1) FI78891C (en)
WO (1) WO1989002419A1 (en)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0845442A1 (en) * 1996-12-02 1998-06-03 Alcatel Apparatus for manufacturing an optical fibre preform
US6363754B2 (en) * 1998-06-24 2002-04-02 Mansoo Choi MCVD method and apparatus using an elongated gas feeding device
KR100456125B1 (en) * 2001-12-06 2004-11-06 엘지전선 주식회사 Apparatus for efficiently removing shoot, for the preparation of optical fiber preform
EP1535884A1 (en) * 2003-11-27 2005-06-01 Samsung Electronics Co., Ltd. Method and apparatus for manufacturing optical fiber preform
KR100556317B1 (en) * 2002-08-07 2006-03-03 엘에스전선 주식회사 Prevention device of soot blocking by using the difference of rotation speed between inner and outer tube in MCVD equipment
EP1801081A1 (en) 2005-12-22 2007-06-27 Draka comteq B.V. Device and method for manufacturing an optical preform
KR100737596B1 (en) 2006-03-06 2007-07-10 엘에스전선 주식회사 Soot removing apparatus for mcvd-process and soot removing method using the same
NL1033763C2 (en) * 2007-04-26 2008-10-28 Draka Comteq Bv Device and method for manufacturing an optical preform.
NL1034059C2 (en) * 2007-06-29 2008-12-30 Draka Comteq Bv Method for manufacturing an optical fiber preform using a vapor deposition process.

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4278459A (en) * 1980-03-03 1981-07-14 Western Electric Company, Inc. Method and apparatus for exhausting optical fiber preform tubes
US4635314A (en) * 1985-04-15 1987-01-13 Itt Corporation Arrangement for removing glass soot from an exhaust tube during optical preform fabrication

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4278459A (en) * 1980-03-03 1981-07-14 Western Electric Company, Inc. Method and apparatus for exhausting optical fiber preform tubes
US4635314A (en) * 1985-04-15 1987-01-13 Itt Corporation Arrangement for removing glass soot from an exhaust tube during optical preform fabrication

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
CHEMICAL ABSTRACTS, Vol. 107, (1987), abstract No. 101 591 b; & JP,A,62 138 338. *

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0845442A1 (en) * 1996-12-02 1998-06-03 Alcatel Apparatus for manufacturing an optical fibre preform
FR2756556A1 (en) * 1996-12-02 1998-06-05 Alsthom Cge Alcatel INSTALLATION FOR MANUFACTURING AN OPTICAL FIBER PREFORM
US5972115A (en) * 1996-12-02 1999-10-26 Alcatel Optical fiber preform fabrication installation
US6363754B2 (en) * 1998-06-24 2002-04-02 Mansoo Choi MCVD method and apparatus using an elongated gas feeding device
KR100456125B1 (en) * 2001-12-06 2004-11-06 엘지전선 주식회사 Apparatus for efficiently removing shoot, for the preparation of optical fiber preform
KR100556317B1 (en) * 2002-08-07 2006-03-03 엘에스전선 주식회사 Prevention device of soot blocking by using the difference of rotation speed between inner and outer tube in MCVD equipment
EP1535884A1 (en) * 2003-11-27 2005-06-01 Samsung Electronics Co., Ltd. Method and apparatus for manufacturing optical fiber preform
EP1801081A1 (en) 2005-12-22 2007-06-27 Draka comteq B.V. Device and method for manufacturing an optical preform
KR100737596B1 (en) 2006-03-06 2007-07-10 엘에스전선 주식회사 Soot removing apparatus for mcvd-process and soot removing method using the same
NL1033763C2 (en) * 2007-04-26 2008-10-28 Draka Comteq Bv Device and method for manufacturing an optical preform.
EP1988062A1 (en) 2007-04-26 2008-11-05 Draka Comteq B.V. Device and method for manufacturing an optical preform
US8192808B2 (en) 2007-04-26 2012-06-05 Draka Comteq, B.V. Apparatus and method for manufacturing an optical preform
NL1034059C2 (en) * 2007-06-29 2008-12-30 Draka Comteq Bv Method for manufacturing an optical fiber preform using a vapor deposition process.
EP2008978A1 (en) 2007-06-29 2008-12-31 Draka Comteq B.V. A method for manufacturing a preform for optical fibres by means of a vapour deposition process
US8168267B2 (en) 2007-06-29 2012-05-01 Draka Comteq B.V. Method for manufacturing a preform for optical fibres by means of a vapour deposition process

Also Published As

Publication number Publication date
FI873952A0 (en) 1987-09-11
FI873952A (en) 1989-03-12
FI78891C (en) 1989-10-10
FI78891B (en) 1989-06-30

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