Method and apparatus for making a profiled tubing and a sleeve

A method of forming a profiled tubing, comprising:

• disposing a mandrel adjacent to a surface of a tubing made of a glass material, the mandrel having a nozzle section with a select cross-sectional profile that will define a final cross-sectional profile of the tubing;
• discharging a gas from a porous circumferential surface of the nozzle section to create a film of pressurized gas between the nozzle section and the surface of the tubing, the film of pressurized gas exerting pressure on the surface of the tubing that is sufficient to locally deform the tubing into conformity with the nozzle section;
• advancing the film of pressurized gas along a length of the tubing;
• and
• heating the tubing such that in any local section of the tubing where the film of pressurized gas is exerting pressure, the local section of the tubing is at a viscosity at which the local section of the tubing can be deformed by the pressure;
• wherein the tubing has an initial circumference before being conformed to the nozzle section and a final circumference after being conformed to the nozzle section, and further comprising selecting the tubing such that a ratio of the initial circumference to the final circumference is between 0.7 and 0.95.

A method of forming a profiled tubing, comprising:

• disposing a mandrel adjacent to a surface of a tubing made of a glass material, the mandrel having a nozzle section with a select cross-sectional profile that will define a final cross-sectional profile of the tubing;
• discharging a gas from a porous circumferential surface of the nozzle section to create a film of pressurized gas between the nozzle section and the surface of the tubing, the film of pressurized gas exerting pressure on the surface of the tubing that is sufficient to locally deform the tubing into conformity with the nozzle section;
• advancing the film of pressurized gas along a length of the tubing;
• and
• heating the tubing such that in any local section of the tubing where the film of pressurized gas is exerting pressure, the local section of the tubing is at a viscosity at which the local section of the tubing can be deformed by the pressure;
• wherein deformation of the tubing into conformity with the nozzle section comprises stretching a wall of the tubing by 5 to 30%.