Methods of forming a glass tube are described. In one embodiment, the method includes heating a glass boule to a temperature above a glass transition temperature of the glass boule, drawing the glass tube from the glass boule in a vertically downward direction, and flowing a pressurized gas through a channel of the glass boule as the glass tube is drawn. The glass boule includes an outer surface defining an outer diameter of the glass boule and a channel extending through the glass boule defining an inner diameter of the glass boule. Drawing the glass tube decreases the outer diameter of the glass boule to an outer diameter of the glass tube and flowing the pressurized gas through the channel increases the inner diameter of the glass boule to an inner diameter of the glass tube. Glass boules, glass tubes, and apparatuses for making the same are also described.

Methods of forming a glass tube are described. In one embodiment, the method includes heating a glass boule to a temperature above a glass transition temperature of the glass boule, drawing the glass tube from the glass boule in a vertically downward direction, and flowing a pressurized gas through a channel of the glass boule as the glass tube is drawn. The glass boule includes an outer surface defining an outer diameter of the glass boule and a channel extending through the glass boule defining an inner diameter of the glass boule. Drawing the glass tube decreases the outer diameter of the glass boule to an outer diameter of the glass tube and flowing the pressurized gas through the channel increases the inner diameter of the glass boule to an inner diameter of the glass tube. Glass boules, glass tubes, and apparatuses for making the same are also described.

An apparatus (100) for making glass tubing (200) of a desired non-circular cross-sectional profile (cf FIG. 3) includes a mandrel (101) adapted for positioning proximate heat-softened tubing. The mandrel (101) has a nose (102) and a nozzle section (120) with a chosen profile that will define a final cross-sectional profile of the tubing. The nozzle section (120) has a feed chamber (140) for receiving a gas from a source (207) and a porous and/or foraminous circumferential surface (132,134) through which the gas can be discharged to an exterior of the mandrel. The gas discharges to the exterior of the mandrel, forming a film of pressurized gas in the gap (314, 318) between the porous circumferential surface (132,134) and the heat-softened tubing (200). A method of forming tubing having a non-circular cross-sectional profile using the apparatus is also provided. A glass sleeve made from the reshaped or formed tubing is also disclosed: a monolithic sleeve made of parallel, opposite, flat and smooth front and back covers for use in an electronic device (cf FIG. 13). Some glass-ceramic materials may also be suitable for the tubing, such as transparent beta spodumene.

An apparatus (100) for making glass tubing (200) of a desired non-circular cross-sectional profile (cf FIG. 3) includes a mandrel (101) adapted for positioning proximate heat-softened tubing. The mandrel (101) has a nose (102) and a nozzle section (120) with a chosen profile that will define a final cross-sectional profile of the tubing. The nozzle section (120) has a feed chamber (140) for receiving a gas from a source (207) and a porous and/or foraminous circumferential surface (132,134) through which the gas can be discharged to an exterior of the mandrel. The gas discharges to the exterior of the mandrel, forming a film of pressurized gas in the gap (314, 318) between the porous circumferential surface (132,134) and the heat-softened tubing (200). A method of forming tubing having a non-circular cross-sectional profile using the apparatus is also provided. A glass sleeve made from the reshaped or formed tubing is also disclosed: a monolithic sleeve made of parallel, opposite, flat and smooth front and back covers for use in an electronic device (cf FIG. 13). Some glass-ceramic materials may also be suitable for the tubing, such as transparent beta spodumene.

A shaped tube (50,51) for use as a component in the fabrication of an antiresonant hollow core optical fibre, the shaped tube having a side wall with a transverse cross-sectional shape comprising a number of major curved portions (52) alternating with the same number of minor substantially straight portions (54), each curved portion (52) having an inwardly curving shape, and each straight portion (54) being equidistant from a central longitudinal axis of the shaped tube (50,51).

In a method of manufacturing a tube of quartz glass by molding a hollow cylinder having a wall thickness of at least 20 mm, the cylinder is continuously fed under rotation about a rotational axis into a heating zone at a relative feed rate V.sub.C, softened and radially expanded under the effect of a gas pressure. A tube strand is continuously formed and is withdrawn at a withdrawal rate V.sub.T. In order to mold thick-walled initial hollow cylinders of quartz glass into tubes with larger diameter, the gas pressure is used as an actuating variable of a diameter regulation for the tube outer diameter or for a geometrical correlated parameter thereof, and in a pressure build-up phase the gas pressure is gradually increased from a lower initial value to a higher final value, and that the following applies to the ratio of V.sub.C and V.sub.T:V.sub.T=V.sub.C±0.2.Math.V.sub.C.

A method of forming an opaque quartz glass component is provided. The method includes (a) providing a starting preform made of quartz glass; (b) heating at least a portion of the starting preform to a predetermined temperature at which the quartz glass of the starting preform has a viscosity in a range of 10E2 to 10E12 poise; and (c) deforming at least a portion of the heated preform at the predetermined temperature to change a shape and/or dimension(s) of the heated perform in order to form the opaque quartz glass component. The starting preform and the heated preform have respective densities of at least 2.15 g/cm.sup.3 and at least 2.10 g/cm.sup.3. The starting perform and the opaque quartz glass component have respective direct spectral transmissions of approximately 0.1-1% and 0.2-3% in the wavelength range of λ=190 nm to λ=4990 nm at a wall thickness of 3 mm and a diffuse reflectance of at least 60% in a wavelength range of λ=190 nm to λ=2500 nm.

A method of forming an opaque quartz glass component is provided. The method includes (a) providing a starting preform made of quartz glass; (b) heating at least a portion of the starting preform to a predetermined temperature at which the quartz glass of the starting preform has a viscosity in a range of 10E2 to 10E12 poise; and (c) deforming at least a portion of the heated preform at the predetermined temperature to change a shape and/or dimension(s) of the heated perform in order to form the opaque quartz glass component. The starting preform and the heated preform have respective densities of at least 2.15 g/cm.sup.3 and at least 2.10 g/cm.sup.3. The starting perform and the opaque quartz glass component have respective direct spectral transmissions of approximately 0.1-1% and 0.2-3% in the wavelength range of λ=190 nm to λ=4990 nm at a wall thickness of 3 mm and a diffuse reflectance of at least 60% in a wavelength range of λ=190 nm to λ=2500 nm.

A method for forming a hollow cylinder, in a single step or in as small a number of steps as possible, into a quartz glass tube with a large outer diameter and high dimensional stability is provided. The cylinder, while rotating about a rotation axis, is softened in portions in a heating zone which is moved at a relative feed rate Va, and the softened portion is radially expanded by a centrifugal force and/or an internal overpressure applied in the hollow cylinder bore so as to form a deformation zone. The tube is continuously shaped with an outer diameter D2 which is greater than that of the hollow cylinder D1. The radial expansion of the softened portion is carried out at a location-dependent radial expansion rate Vr, the profile of which along the deformation zone has a maximum value Vr,max which is smaller than two times the feed rate Va.

A method for forming a hollow cylinder, in a single step or in as small a number of steps as possible, into a quartz glass tube with a large outer diameter and high dimensional stability is provided. The cylinder, while rotating about a rotation axis, is softened in portions in a heating zone which is moved at a relative feed rate Va, and the softened portion is radially expanded by a centrifugal force and/or an internal overpressure applied in the hollow cylinder bore so as to form a deformation zone. The tube is continuously shaped with an outer diameter D2 which is greater than that of the hollow cylinder D1. The radial expansion of the softened portion is carried out at a location-dependent radial expansion rate Vr, the profile of which along the deformation zone has a maximum value Vr,max which is smaller than two times the feed rate Va.