Patent ID: 8776548

Claim:
A method, comprising: obtaining a tubular glass pre-form having a tubular pre-form wall with an open end, a closed end, and a middle section between the open end and the closed end, all aligned in a longitudinal direction, the middle section of the glass pre-form including at least a first midsection and a second midsection adjacent to the first midsection, the open end of the glass pre-form opening into a cavity extending into the pre-form at least through the second midsection to the first midsection; heating the first midsection of the glass pre-form by centripetally applying heat from a localized heat source to the first midsection of the glass pre-form; blowing a gas into the open end to expand the cavity at the heated first midsection and to blow the heated first midsection, thereby substantially laterally expanding a diameter of the cavity in the first midsection of the glass pre-form and thinning the pre-form wall in the first midsection; blowing a gas against an exterior surface of the glass pre-form to limit expansion of the first midsection to a desire width; longitudinally drawing the heated first midsection in the longitudinal direction of the glass pre-form, thereby thinning the pre-form wall in the first midsection; advancing the pre-form in the longitudinal direction relative to the localized heat source such that: (i) at least a portion of the first midsection of the perform is advanced longitudinally away from the localized heat source and the heat therefrom is no longer centripetally applied to such portion, and (ii) the second midsection of the perform is advanced longitudinally toward and into proximity with the localized heat source and the heat from the localized heat source is centripetally applied to the second midsection of the glass pre-form; and repeating the heating, blowing, and drawing steps on the second midsection.