Heraeus Quarzglas Gmbh & Co Kg

Rene Sowa

Jan Vydra

Ralph Sattmann

Martin Trommer

Oliver Ganz

Clemens Schmitt

Peter Bauer

Udo Peper

Norbert Cibis

Anke Schuster

In a known process for producing a quartz glass cylinder, a porous soot tube, which is sintered to form the quartz glass cylinder, is produced by depositing SiOparticles on an outer cylindrical surface of a support, which rotates about the longitudinal axis thereof and has a layer of silicon carbide (SiC layer). In order on this basis to specify a support having a high resistance to fracture, which firstly can easily be removed and which secondly presents a low risk of contamination for the soot body, the invention proposes that the SiC layer is treated at a high temperature in an oxygen-containing atmosphere before the SiOparticles are deposited, in such a manner that an SiOprotective layer having a thickness of at least 0.1 &#x3bc;m is produced by oxidation.

Process for producing a quartz glass cylinder and also support for carrying out the process

A known method for producing a cylinder of quartz glass comprises a soot depositing process, in which SiOparticles are deposited on an elongate carrier rotating about an axis of rotation with formation of a porous, hollow-cylindrical soot body, and a sintering process in which the soot body comprising an inner bore with inner wall, a longitudinal axis, an upper end and a lower end is held suspended in vertical orientation in a furnace, a holding element being provided for holding purposes, which projects from the upper end into the inner bore of the soot body and acts on a bearing provided in the inner bore. Starting from this, to indicate a method by means of which even heavy bodies of porous SiOwith a small inner diameter can be safely held during sintering, it is suggested according to the invention that the bearing should be provided as an expanding bearing having at least one spreading element which is movable against the inner wall of the inner bore and which under the action of the holding element performs a movement with a movement component in a direction perpendicular to the longitudinal axis of the soot body and is pressed against the inner wall.

Method for producing a cylinder of quartz glass and holding device for carrying out the method

The production of an optical component from quartz glass by elongation of a coaxial arrangement of a core rod and a hollow cylinder is known. The arrangement is thus introduced into a heating zone, such that the lower end begins to partly soften and the component drawn from the softened part. According to the invention, a pseudo-continuous method for the formation of the restriction in the inner passage of the hollow cylinder on which the core rod is supported, is disclosed, whereby an upper hollow cylinder is fused end on with a lower hollow cylinder to form an axial composite cylinder, a core rod is introduced into the lower hollow cylinder and the axial cylinder composite partly softened and elongated to form the optical component. A drawing bulb extending to the upper hollow cylinder forms, within which the inner passage at least partly collapses with formation of the restriction and the upper cylinder is then separated off from the drawn optical component at a separating plane and then elongated together with a core rod to form an optical component.

Method for production of an optical component from quartz glass

The production of an optical component from quartz glass, by elongation of a coaxial arrangement of a core rod and a hollow cylinder of a given length, is known. The arrangement is thus introduced into a heating zone with a vertical orientation, such that the lower end begins to partly soften and the component is drawn downwards from the softened part. The hollow cylinder has an inner passage, provided with a restriction in the region of the lower end thereof, on which the core rod is supported. Several methods are disclosed for formation of the restriction in which the inner passage () is mechanically machined to a final dimension and, in one version of the method, the restriction in the inner passage () is generated by means of softening the lower end face of the hollow cylinder, swaged against a tool and thus folded inwards with formation of a peripheral bead ring.

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Pouch, Germany

Rene Sowa