Patent ID: 7600399

Claim:
A method for producing a cylindrical glass body in a vertical drawing process, said method comprising: a method step in which a glass blank is supplied to a heating zone, and softened therein zonewise, and a glass strand is drawn off using a draw-off device at a controlled drawing speed from the softened area, said draw-off device comprising a first draw-off unit having rolling bodies rolling on said glass strand and being distributed around the circumference thereof, said rolling bodies of said draw-off device including a reference rolling body and at least one auxiliary rolling body, said reference rolling body and said auxiliary rolling body or bodies each having a respective varying torque acting thereon dependent on a variable weight of the drawn-off glass strand, the drawing speed being controlled by setting a speed of said reference rolling body, said draw-off device further comprising at least one additional draw-off unit including a plurality of additional rolling bodies each rolling on the glass strand, wherein a value correlated to the torque acting on said reference rolling body is determined and the determined value is used as a setpoint torque based on which the torque acting on said at least one auxiliary rolling body and the torques acting on said additional rolling bodies of said at least one additional draw-off unit are adjusted so as to equalize the torque acting on said reference rolling body and the torques acting on said at least one auxiliary rolling body and said additional rolling bodies and so that all of the rolling bodies exert the same forces on the glass strand, and wherein said value is determined repeatedly or continuously, and the setpoint torque is a variable setpoint torque used to repeatedly or continuously adjust the torques of said at least one auxiliary rolling body and said additional rolling bodies as the glass strand depending therefrom changes in weight as the cylindrical glass body is drawn.