A sealing arrangement for a drawing furnace including a vertical center hole with surrounding heating elements for receiving a glass preform including a tapered portion connected to an extension rod. A sealing with an opening is arranged on top of the furnace. The arrangement includes an outer annular bushing arranged on top of the furnace and an inner annular bushing with a first and an opposing second vertical end. The inner bushing is positionable to surround at least part of the tapered portion with the first end positioned to the region of the beginning of the tapered portion and the second end includes protrusions on the outer surface. As the inner bushing is inserted in the outer bushing it is arranged to be movable within the outer bushing and the protrusions form supports for holding the second end of the inner bushing above the center hole.

A system for positioning an optical preform in a furnace is provided that includes an upper muffle and a downfeed handle assembly with a tube defining a first end and a second end, the second end extending into the upper muffle. A handle is disposed within the tube. A second end of the handle extends into the upper muffle and a seal assembly is positioned around both the tube and the handle. The first end of the handle extends through the seal assembly and a drive assembly is coupled with the downfeed handle.

A method of forming an optical fiber, the method including heating a forming region of the optical fiber preform within a pressure device while exposing the forming region to a total pressure of about 500 atm or greater, directing the optical fiber preform in a downstream direction along a process pathway to form the optical fiber, and traversing the optical fiber through an aperture of a nozzle to maintain the total pressure of about 500 atm or greater within the pressure device.

The invention relates to an apparatus. In order to achieve efficient sealing, the apparatus includes a sealing with a plurality of sealing elements arranged generally in a ring configuration around a center opening. Each sealing element includes a sealing surface facing the center opening. At least one chamber is included for receiving sections of the sealing elements. An inlet to a fluid source provides the at least one chamber with fluid in order to generate an overpressure acting on the sections of the sealing elements received in the at least one chamber, and for pressing and moving the sealing surfaces of the sealing elements towards the center opening.

An apparatus for drying and/or consolidating an at least partially porous optical fibre preform, including: a furnace having a muffle tube extending along a vertical axis and forming a muffle chamber configured to house a preform, the muffle tube having a muffle upper opening at its top side, which is configured to allow passage of the preform; a hollow connection member having an inner diameter configured to allow passage of the preform and extending along the vertical axis, the connecting member being removably connected to the muffle tube at the muffle opening; a hood positioned on top of the connection member, the hood being removably connected to or integral with the connection member, the hood having an interior space in vertical alignment with the connection member, in which the hood includes a hood lid closing the hood at its top, in which the hood lid includes a through-hole axially aligned with the muffle opening, the hood lid through-hole being configured for the passage of a cylindrical supporting rod of a supporting handle for the suspension of the preform, and a sealing assembly including a first sealing element housed within the interior space of the hood and a second sealing element on top of the hood lid, both the first and the second sealing element being substantially centred on the vertical axis, in which the first sealing element and second sealing element include a respective first and second ring-shaped seal and a first and second expansible member having a generally tubular shape configured to allow passage of the supporting rod and to expand, contract and bend, in which each first and second ring-shaped seal is located radially inward of the respective first and second expansible member and operatively connected thereto, the respective ring-shaped seals being sized to directly contact the supporting rod.

An apparatus for drying and/or consolidating an at least partially porous optical fibre preform.

Embodiments are directed to systems and methods for material processing in a low gravity environment, and an optical fiber formed in a low gravity environment. The system established the control of both the temperature and the temperature gradients to compensate for the effects of microgravity environment. The control of the neck-down region during the fiber draw in microgravity through the controlled temperature distribution in the work volume delivers steady-state process for microgravity manufacturing.

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 preform 11 is sealed with a first seal part 17 of the seal mechanism. After a vicinity of a taper part of the optical fiber glass preform 11 starts to pass through the first seal part 17, switching to a second seal part 18 arranged above the first seal part 17 is performed, and an outer peripheral surface of a sleeve member 20 fixed so as to surround an outer periphery of the dummy rod 12 is sealed with the second seal part 18.

A flexible sealing assembly (100) for an optical fiber draw furnace (500) comprising a first plurality of curved ring sections (110) arranged in a circular arrangement and a plurality of tension loaders (114) exerting continuous radially inward force on at least one curved ring section. Each curved ring section of the first plurality of curved ring sections (110) is separated from each other and defined by the same radius of curvature. Further, the first plurality of curved ring sections (110) is radially movable such that the first plurality of curved ring sections (110) creates a seal between a glass preform (504) and a vertical hollow body (506) in the optical fiber draw furnace (500). The diameter of the glass preform (504) varies.

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.