Patent DE-102006015223-B3 (DE)
Title: Production of glass tube comprises redrawing glass tube preform with initial profile and recasting of glass tube preform into glass tube with another profile
Inventor: BUELLESFELD FRANK
IPC: C03B23/055
Filed: 2006-03-30
Granted: 2007-08-30
Abstract: The production of a glass tube (6) comprises redrawing a glass tube preform (4) with an initial profile and recasting of the glass tube preform into a glass tube with another profile. The glass tube preform traverses a hot zone (1) to form a drawn bulb-shaped structure (5), and the glass tube preform, which is downstream to the drawn bulb-shaped structure, is recast to the glass tube by a pair of rollers (7). The position of the rollers is adjusted to be parallel and/or perpendicular to the direction of drawing of the glass tube during the drawing of the preform glass tube. The production of a glass tube (6) comprises redrawing a glass tube preform (4) with an initial profile and recasting of the glass tube preform into a glass tube with another profile. The glass tube preform traverses a hot zone (1) to form a drawn bulb-shaped structure (5), and the glass tube preform, which is downstream to the drawn bulb-shaped structure, is recast to the glass tube by a pair of rollers (7). The position of the rollers is adjusted to be parallel and/or perpendicular to the direction of drawing of the glass tube during the drawing of the preform glass tube. A measured variable that represents the perimeter of the glass tube with another profile, is determined and on the basis of the measured variable, a first process parameter is regulated in such a manner that the perimeter of the glass tube is constant. The first process parameter is specified by adjusting rollers in the direction of drawing of the glass tube, forming the width of a roller gap by the pair of rollers or applying a positive pressure to an interior of the drawn bulb-shaped structure. The position of the rollers is adjusted by shifting the same parallel to the direction of drawing of the glass tube. The glass tube preform is recast to a rectangular glass tube in such a manner that a dimension of the other profile is longer in a direction perpendicular to the roller gap than in a direction parallel to the roller gap. The glass tube preform exhibits a circular initial profile and/or the glass tube with the other profile is an oval pipe. A pre-determined wall thickness of the glass tube is adjusted by changing the positive pressure. A second measured variable, which represents an external dimension of the glass tube in the direction of the roller gap or perpendicularly to it, is determined and on the basis of the second measured variable, a second process parameter is regulated in such a manner that the external dimension of the glass tube in the direction of the roller gap is constant and the temperature of the hot zone and/or the feed velocity and/or the withdrawal velocity of the glass tube preform is altered. The pair of rollers and/or a process parameter is adjusted before activating the regulation in a control range corresponding to the other profile. The process parameter is specified on the basis of the rapidly cooled down redrawn glass tube. A proportional integral differential (PID) controller is used for regulation. The glass tube preform is passed through the hot zone with a first pre-determined velocity and the glass tube with the other profile is withdrawn with a constant second velocity. An independent claim is included for a device for the production of a glass tube.