Sumitomo Electric Industries, Limited

Iwao Okazaki

Takashi Yamazaki

Tatsuya Konishi

Takahiro Saito

Satoshi Yoshikawa

Masatoshi Hayakawa

Tadashi Enomoto

Makoto Aoki

Shinji Ishikawa

Manabu Shiozaki

Tetsuya Haruna

Ichiro Tsuchiya

Katsuyuki Tsuneishi

Keisei Morita

Motohide Yoshida

Kazuyuki Soma

Yoshihiro Morimoto

Fumio Yoshimura

Yuuki Shibuya

Norihiro Uenoyama

Masaru Furusyou

This seal structure of a wire drawing furnace for an optical fiber is for sealing a gap between an upper end opening of the wire drawing furnace for an optical fiber and a glass base material for an optical fiber inserted from the upper end opening into a furnace core tube. This seal structure has: a plurality of blade members circumferentially arranged in contact with a circumferential side surface of the glass base material for an optical fiber; a guide member, provided around the plurality of blade members, for allowing the plurality of blade members to slide linearly toward the circumferential side surface of the glass base material for an optical fiber; and a pushing/pulling action mechanism that causes the blade members to move in the radial direction of the glass base material for an optical fiber. The center of gravity of the plurality of blade members is located behind the tip surface of the guide member.

Seal structure of wire drawing furnace for optical fiber, and production method for optical fiber

A method for manufacturing an optical fiber coats a first resin on a glass fiber drawn from a glass base material, and cures the first resin to form a first coating. The method includes causing the glass fiber to travel at a first velocity during a first time period, increasing the velocity from the first velocity to a second velocity during a second time period following the first time period, and maintaining the velocity at the second velocity during a third time period following the second time period. A relationship 1.0<TB/TB<=11.0 stands, where TBdenotes a thickness of the first coating in the increasing, from a start of coating the first resin to a time when the velocity reaches a third velocity higher than the first velocity and lower than the second velocity, and TBdenotes a thickness of the first coating in the maintaining.

Method for manufacturing optical fiber

An optical fiber manufacturing method includes a first process of passing a glass fiber through a fiber path. The fiber path is formed through a cooling tube that is housed in a first casing. The method also includes a second process of leading the glass fiber into a second casing before leading into the first casing. The first process includes supplying a first dry gas, having a dew point lower than the temperature of the cooling tube, into a first dry space formed between the first casing and the cooling tube. The second process includes supplying a second dry gas into a second dry space formed inside the second casing so as to cause air pressure in the second dry space to be higher than air pressure in an external space. The dew point of the second dry gas is lower than the dew point in the external space.

Optical fiber manufacturing method and optical fiber manufacturing apparatus

An optical fiber drawing method where a glass base material passes through an opening provided in a drawing furnace from the material side and drawing is performed by suspending and descending the material into the drawing furnace while being sealed by a sealing mechanism provided in the vicinity of the opening, in which a first portion of the sealing mechanism seals a gap between an outer peripheral surface of the material and an inner surface of the opening when drawing starts and a tapered portion of the material starts passing through the first portion, and a second portion is disposed above the first portion before sealing by the first portion becomes ineffective, and then conduction between inside and outside of the drawing furnace is carried out to prevent fluctuation of pressure inside the furnace immediately after disposing the second portion and the conduction is interrupted when the material further descends.

Optical fiber drawing method and drawing apparatus

An optical fiber manufacturing method includes a process of passing a glass fiber through a fiber path before applying a resin. The glass fiber is drawn from a glass preform, the fiber path is formed through a cooling tube, and the cooling tube is housed in a casing and is cooled by a coolant. The process includes supplying a dry gas into a dry space formed between the casing and the cooling tube. The dry gas has a first dew point lower than the temperature of the cooling tube. The process includes measuring, by a dew point meter, a second dew point at one or both of an inlet and an outlet of the fiber path. The process includes controlling the temperature of the coolant in the cooling tube such that the temperature of the cooling tube is higher than the second dew point measured by the dew point meter.

In a method for manufacturing an optical fiber, a dummy rod is connected to a vicinity of an upper end of a glass preform which includes a diameter-reduced portion at an upper portion thereof, and the glass preform is heated to be melt in a drawing furnace to draw an optical fiber. A cap member is provided at a position of the diameter-reduced portion, and an upper end of the cap member is disposed close to a lower end of the dummy rod. When an orthogonal coordinate axis is set, in which an outer diameter ratio of the cap member to the glass preform is set as a horizontal axis x, and an outer diameter ratio of the dummy rod to the glass preform is set as a vertical axis y, the x and the y satisfy an expression y&#x2265;0.1527&#xd7;x.

A seal structure of an optical fiber drawing furnace for sealing a gap between an upper end opening of the optical fiber drawing furnace and an optical fiber glass preform inserted from the upper end opening, includes a plurality of blade members, a support mechanism for supporting the plurality of blade members, and a pressing operation mechanism for individually pressing the plurality of blade members in a radial direction of the optical fiber glass preform so as to bring distal ends of the plurality of blade members into contact with a side surface of the optical fiber glass preform, wherein a pressing force at the time of bringing the plurality of blade members into contact with the optical fiber glass preform is set at 0.1 to 10 N per blade member.

Seal structure of optical fiber drawing furnace, and method for drawing optical fiber

Capacity of space in a drawing furnace is decreased so as to reduce variations in pressure in the furnace and also the side of an insertion port of a glass perform is stably sealed. When drawing is started, an outer peripheral surface of the optical fiber glass preformis sealed with a first seal partof the seal mechanism. After a vicinity of a taper part of the optical fiber glass preformstarts to pass through the first seal part, switching to a second seal partarranged above the first seal partis performed, and an outer peripheral surface of a sleeve memberfixed so as to surround an outer periphery of the dummy rodis sealed with the second seal part

Optical fiber drawing method and optical fiber drawing apparatus

An apparatus includes a susceptor and a protective pipe. A gas containing 50% or more of argon or nitrogen is used as a gas to be supplied into the susceptor. The protective pipe has a heat insulating region () enclosed with a heat insulator () with a length of Db (mm) at the upper section thereof and a non-heat insulating region () not enclosed with any heat insulators at the lower section thereof. The temperature of the glass fiber at the outlet of the protective pipe becomes 1700&#xb0; C. or less. The outer diameter of the glass fiber at the outlet of the protective pipe is within a range of the target outer diameter of the glass fiber+6 &#x3bc;m or less.

Optical fiber producing method and apparatus and optical fiber

The present invention provides a glass preform heating furnace in which the occurrence of arching is suppressed. The glass preform heating furnace is equipped with a susceptor (); a slit heater (); an insulator; and a furnace body, wherein, in the case that the space between the slit heater () and the susceptor or between the slit heater () and the conductive member closest to the slit heater is D, that the maximum value of the electric field in this space is E, that the number of the slits in the slit heater is N, that the slit width of the slit heater is S, and that the maximum value of the electric field in the slit space is E, the values of D, N and S are set so that E&#x2267;Eis established.

Glass preform heating furnace

Based on an intermediateA in which a cladding portionis formed on the outer periphery of a core portion, a pair of holesandare provided parallel to the z axis on both sides of the core portionwithin the cladding portion, and an intermediateis thereby fabricated. In this intermediate, a width Ry in the y-axis direction is made smaller than a width Rx in the x-axis direction. Moreover, a cylindrical stress applying partis inserted into a holeof the intermediate, and a cylindrical stress applying partis inserted into a holethereof. Thus, a preformis formed. These materials are drawn and integrated together, and a polarization maintaining optical fiber is thereby manufactured.

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Yokohama, Japan

Iwao Okazaki