Patent ID: 6134920
Filing Date: 2000-10-24
Classification: C03B

Abstract:
A method of plastically forming an axially extended zone of the interior surface of a hollow glass tube heated to its forming temperature, comprising the following steps:a) bringing the hollow glass tube and a generally cylindrical embossing mandrel connected to a driving shaft together at a predetermined start position for the embossing mandrel inside the glass tube;b) bringing the embossing mandrel and the interior surface of the glass tube into contact in an area in which the zone is to be formed;c) providing a relative rolling off planetary motion between the embossing mandrel and the glass tube while plastically forming the zone of the glass tube and creating depressions therein, the rolling off planetary motion comprising (i) rotating the embossing mandrel around the longitudinal axes of the embossing mandrel and the glass tube, (ii) rotating the embossing mandrel around its longitudinal axis and rotating the glass tube around its longitudinal axis, or (iii) rotating the glass tube around the longitudinal axes of the glass tube and the embossing mandrel; andd) separating the glass tube and the embossing mandrel.