A method for homogenizing glass includes the method: providing a cylindrical blank composed of the glass having a cylindrical outer surface that extends along a longitudinal axis of the blank between a first end face and a second end face, forming a shear zone in the blank by softening a longitudinal section of the blank and subjecting it to a thermal-mechanical intermixing treatment, and displacing the shear zone along the longitudinal axis of the blank. The displacement of the shear zone along the longitudinal axis of the blank is superimposed by a simultaneous oscillating motion of the shear zone along the longitudinal axis of the blank. The first end of the blank is rotated at a first rotational speed and the second end of the blank is rotated at a second rotational speed. An oscillating motion of the shear zone is generated by periodically varying the first and/or second rotational speed.

A method for homogenizing glass includes the method: providing a cylindrical blank composed of the glass having a cylindrical outer surface that extends along a longitudinal axis of the blank between a first end face and a second end face, forming a shear zone in the blank by softening a longitudinal section of the blank and subjecting it to a thermal-mechanical intermixing treatment, and displacing the shear zone along the longitudinal axis of the blank. The displacement of the shear zone along the longitudinal axis of the blank is superimposed by a simultaneous oscillating motion of the shear zone along the longitudinal axis of the blank. The first end of the blank is rotated at a first rotational speed and the second end of the blank is rotated at a second rotational speed. An oscillating motion of the shear zone is generated by periodically varying the first and/or second rotational speed.

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 glass tube element having a hollow cylindrical section with a shell having an outer diameter is provided. A first ratio is a difference value to a mean value. The difference value is a difference of a minimal and maximal value of the outer diameter. The mean value is a mean of the minimal and maximal values. A sub-section having a start, an end, and a distance of 1 meter measured along a straight line from the start to the end and intersecting with a center axis of the sub-section at the start and the end. The sub-section having, for every point of the center axis, a shortest distance to the straight line. A second ratio of a specific distance to 1 meter, the specific distance being defined as a largest of all shortest distances. A product of the first and second ratio is smaller than 4×10.sup.−6.

Methods for producing articles from a glass tube include securing a working end of the glass tube in a glass tube holder of a converter having a plurality of processing stations including a heating station and a forming station. An initial length of the glass tube includes a plurality of serial segments, each of the plurality of serial segments corresponding to one article and having an article number. The methods include heating the working end of the glass tube in the heating station, adjusting an amount of heating of the glass tube in the heating station based on the article number at the working end of the glass tube, and forming a feature of the article in the forming station. Adjusting the amount of heating based on the article number reduces variation in tube temperature, article dimensions, or both, from one article number to the next article number.

Methods for producing articles from a glass tube include securing a working end of the glass tube in a glass tube holder of a converter having a plurality of processing stations including a heating station and a forming station. An initial length of the glass tube includes a plurality of serial segments, each of the plurality of serial segments corresponding to one article and having an article number. The methods include heating the working end of the glass tube in the heating station, adjusting an amount of heating of the glass tube in the heating station based on the article number at the working end of the glass tube, and forming a feature of the article in the forming station. Adjusting the amount of heating based on the article number reduces variation in tube temperature, article dimensions, or both, from one article number to the next article number.

Methods for producing glass articles from glass tube includes securing a glass tube in a holder of a converter; rotating the glass tube; and passing the glass tube through processing stations, which include at least a heating station and a forming station, to form one or more features at a working end of the glass tube. An active time is an amount of time the glass tube is engaged with a heating element or a forming tool while in a processing station, and an exposure index for the processing station is the rotational speed of the glass tube multiplied by a number of heating elements or forming tools in the processing station multiplied by the active time. An absolute difference between the exposure index and a nearest integer is less than or equal to 0.30, which reduces temperature and dimensional inhomogeneity around a circumference of the glass tube.

Systems for producing articles from glass tube include a converter having a base with a plurality of processing stations and a turret moveable relative to the base. The turret indexes a plurality of holders for holding the glass tubes successively through the processing stations. The systems further include a gas flow system or a suction system for producing a flow of gas through the glass tube during one or more heating, forming, separating or piercing operations. The flow of gas through the glass tube produced by the gas flow system or suction system may be sufficient to evacuate or purge volatile constituents of the glass from the glass tube and/or pierce a meniscus formed on the glass tube during separation, thereby reducing the Surface Hydrolytic Response (SHR) of the interior surface of the glass tube and articles made therefrom.