Method for producing a glass tube with a cross section of a noncircular form by reshaping

Method for producing a glass tube with a cross section of a noncircular form by reshaping, comprising at least the steps of:

• providing a glass tube having a longitudinal axis and an outer surface,
• heating the glass tube, providing at least one reshaping tool having an interior, which has a forming body with a forming area for reshaping the heated glass tube, the forming body comprising at least one open-porous material,
• setting a gas pressure in the interior of the at least one reshaping tool that is lower than 90 kPa, so that a negative pressure is produced on the forming area of the forming body, and
• reshaping the heated glass tube by applying a compressive force perpendicularly to the longitudinal axis of the glass tube, the compressive force being generated by the at least one reshaping tool and being applied to the outer surface of the glass tube,
• characterized in that the outer surface of the glass tube is fixed by the negative pressure on the forming area of the forming body.

Method for producing a glass tube with a cross section of a noncircular form by reshaping, comprising at least the steps of:

• providing a glass tube having a longitudinal axis and an outer surface,
• heating the glass tube, providing at least one reshaping tool having an interior, which has a forming body with a forming area for reshaping the heated glass tube, the forming body comprising at least one open-porous material,
• setting a gas pressure in the interior of the at least one reshaping tool that is lower than 90 kPa, so that a negative pressure is produced on the forming area of the forming body, and
• reshaping the heated glass tube by applying a compressive force perpendicularly to the longitudinal axis of the glass tube, the compressive force being generated by the at least one reshaping tool and being applied to the outer surface of the glass tube,
• characterized in that the outer surface of the glass tube being made to lie against at least part of the forming area by the negative pressure on the forming area of the forming body.