Abstract: A method for using a temperature control loop in order to further develop process control during elongation of a cylindrical preform such that a component strand with high dimensional accuracy can be drawn even in the presence of temperature-effective defects during the elongation process: (a) the continuous measurement of a first temperature value, Ttop, at an upper measuring point on the surface of the cylindrical preform; (b) the continuous measurement of a second temperature value, Tbottom, at a lower measuring point; (c) calculation of a temperature distribution in the region between the measuring points Ttop and Tbottom, and determination of a modelled deformation temperature, Tmodel, using an algorithmic model taking with first and the second temperature values as model input parameters, and the modelled deformation temperature, Tmodel, as a regulating variable and the heating-zone temperature Toven as a manipulated variable for the temperature-control loop.

Abstract: A method for using a temperature control loop in order to further develop process control during elongation of a cylindrical preform such that a component strand with high dimensional accuracy can be drawn even in the presence of temperature-effective defects during the elongation process: (a) the continuous measurement of a first temperature value, Ttop, at an upper measuring point on the surface of the cylindrical preform; (b) the continuous measurement of a second temperature value, Tbottom, at a lower measuring point; (c) calculation of a temperature distribution in the region between the measuring points Ttop and Tbottom, and determination of a modelled deformation temperature, Tmodel, using an algorithmic model taking with first and the second temperature values as model input parameters, and the modelled deformation temperature, Tmodel, as a regulating variable and the heating-zone temperature Toven as a manipulated variable for the temperature-control loop.

Abstract: The present invention refers to a drawing method for producing cylindrical components of quartz glass in that a quartz glass strand is drawn off in the direction of a drawing axis from a shaping zone of soft quartz glass mass and sections having a cutting length are separated from the quartz glass strand, and the cylindrical components are produced from the sections.

Abstract: In a known drawing method for producing cylinder-shaped components from quartz glass, a quartz glass strand (10) is drawn in the direction of a drawing axis (12) from a deformation region of a quartz glass mass (9) and pieces having a cutting length (S) are separated therefrom. The cylinder-shaped components are produced from the pieces. In order to provide a simple drawing method for producing quartz glass components, wherein the effects of geometric disruptions, in particular variations in diameter and material rejects, are reduced, the separation of the quartz glass strand (10) is carried out at a separating position (T), wherein the distance of the separating position from the deformation region (9) is set in a way such that a disruption of the quartz glass strand geometry created by the separation lies in an end region of the component to be produced or between two neighboring components during a subsequent separation.

Abstract: In a known method for producing a tube of quartz glass by elongating a hollow cylinder of quartz glass having an outer diameter AD, said cylinder is continuously supplied to a heating zone with a vertically oriented heating tube having an inner diameter d, with the proviso that the diameter ratio d/AD is set to a value ranging from 1.02 to 1.7. The hollow cylinder is softened therein zonewise, and a tubular strand is drawn off from the softened region and shortened to obtain the tube. Starting therefrom, in order to optimize the dimensional stability of the quartz glass tube obtained, it is suggested according to the invention that the heating zone should have a length L which is set such that the ratio L/d is smaller than 0.9.

Abstract: According to a known vertical drawing method for producing a cylindrical glass body, the cylinder longitudinal axis of the glass cylinder is adjusted by hand in relation to the longitudinal axis of a heating tube. The aim of the invention is to optimize the stability of said glass body.

Abstract: In a known method for producing a tube of quartz glass by elongation, a hollow cylinder of quartz glass is continuously supplied to a heating zone, softened therein zone by zone, and a tube strand is drawn in the direction of a drawing axis out of the softened region by using a roll puller, the roll puller comprising a frame by which a plurality of puller rolls are fixed, which are rotatable around a rotation axis and which are distributed over the circumference of the tube strand and adjoining the tube strand with their cylindrical outer surface.

Abstract: In a known method for producing a cylindrical glass body in a vertical drawing process, a glass blank is softened in a heating zone and drawn off as a glass strand by means of a draw-off device at a controlled drawing speed, the draw-off device comprising a first draw-off unit with rolling bodies rolling on the glass strand and being distributed around the circumference thereof, the rolling bodies being formed by a reference rolling body and at least one auxiliary rolling body, the drawing speed being controlled via the speed of the reference rolling body.

Abstract: In a known method for producing a tube of quartz glass by elongating a hollow cylinder of quartz glass 6b having an outer diameter AD, said cylinder is continuously supplied to a heating zone with a vertically oriented heating tube having an inner diameter d, with the proviso that the diameter ratio d/AD is set to a value ranging from 1.02 to 1.7. The hollow cylinder is softened therein zonewise, and a tubular strand is drawn off from the softened region and shortened to obtain the tube. Starting therefrom, in order to optimize the dimensional stability of the quartz glass tube obtained, it is suggested according to the invention that the heating zone should have a length L which is set such that the ratio L/d is smaller than 0.9.

Abstract: According to a known vertical drawing method for producing a cylindrical glass body, the cylinder longitudinal axis of the glass cylinder is adjusted by hand in relation to the longitudinal axis of a heating tube. The aim of the invention is to optimise the stability of said glass body.

Abstract: A resistance furnace has a tubular heating element with a vertically-oriented longitudinal axis. The heating element has a shell surface defined by an upper side and a lower side and surrounding a furnace chamber. The heating element is connected to at least two supply terminals by which heating current is introduced at power supply points into the heating element. The supply terminals include a surrounding upper annular collar adjacent the upper side of the shell surface, and also a surrounding lower annular collar adjacent the lower side of the shell surface.

Abstract: In a known method for producing a cylindrical glass body in a vertical drawing process, a glass blank is softened in a heating zone and drawn off as a glass strand by means of a draw-off device at a controlled drawing speed, the draw-off device comprising a first draw-off unit with rolling bodies rolling on the glass strand and being distributed around the circumference thereof, the rolling bodies being formed by a reference rolling body and at least one auxiliary rolling body, the drawing speed being controlled via the speed of the reference rolling body.

Abstract: A known resistance furnace comprises a tubular heating element having a vertically oriented longitudinal axis, which comprises a shell surface defined by an upper side and a lower side and surrounding a furnace chamber, and which is connected to at least two supply terminals by means of which heating current is introduced at power supply points into the heating element. Starting from the above, in order to provide an electric resistance furnace, in particular a high-performance resistance furnace which is characterized by small manufacturing and maintenance efforts and by a high operational reliability, and which permits the reproducible adjustment of an axially and radially homogeneous temperature profile within the furnace, it is suggested according to the invention that the supply terminals should comprise a surrounding upper annular collar (7) in the region of the upper side (11) and a surrounding lower annular collar (8) in the region of the lower side (12).

Abstract: In a known method for the manufacture of a solid quartz glass cylinder (18) by drawing from a hollow quartz glass cylinder (5) in a vertical drawing process, the hollow cylinder (5) is passed to a heating zone (4), softened therein in one area after the other and the solid cylinder (18) is drawn off from the softened area (15) with a reduced inside pressure (P1) being maintained in the inside bore (19) of the hollow cylinder (5) versus an outside pressure (P2) applied on the outside thereof.

Abstract: In a known method for the manufacture of a tube made of a vitreous material, especially of quartz glass, a hollow cylindrical semifinished product made of a vitreous material is carried essentially vertically to a heating zone, wherein it is heated and drawn off downwards—without the use of tools—to the tube by forming a transitional area from semifinished product to tube, while diameter and wall thickness of the tube are continuously measured, and the tube's measured geometrical data being used to generate a control signal with the aid of which a pressure difference is regulated between pressure P1 in the interior space of the semifinished product, the transitional area and the tube, as well as pressure P2 in the heating chamber which is regulated in the heating zone at least in the transitional area from semifinished product to tube and its adjacent tube area.

Abstract: A glass blank is sent to a heating zone where it is softened region by region and drawn continuously in a controlled manner as a drawing bulb is formed. Estimates of at least one controlled variable are predicted free of dead time; in addition, at least one geometric variable of the component which can be correlated with the controlled variable is measured continuously, and the measurement values thus obtained are used to adjust the predicted estimates. On the basis of the predicted estimates thus adjusted, the nominal-actual deviation of the controlled variable is determined and converted to a change in a controlling variable. To ensure the production of a component with especially high dimensional accuracy, a geometric variable is measured at a first measurement site in the area of the drawing bulb for the prediction of the estimate, and the temperature of the drawing bulb be measured and used as a controlled variable.