Schott Ag

Friedrich-Georg Schroeder

Gerhard Hahn

Martin Taplan

Wolfgang Schmidbauer

Herwig Scheidler

Bernd Hoppe

Falk Gabel

Otmar Becker

Dietmar Wennemann

Torsten Gabelmann

Harald Striegler

Helga Goetz

Ioannis Kosmas

Michael Bug

Roland Hochhaus

Dieter Schoenig

Veit Luther

Thoralf Johansson

Petra Grewer

Jan-Peter Ortmann

Hans-Walter Abraham

Hermann Lemm

Michael Glasenapp

Bernd Weitzel

Thomas Schuler

Guenther Siebenhaar

A lithium-containing, transparent glass-ceramic material is provided. The material has low thermal expansion and has an amorphous, lithium-depleted, vitreous surface zone. The zone is at least 50 nm thick on all sides and encloses a crystalline interior, which has high transmission. The material includes a transition region connecting the zone and the interior.

Transparent lithium glass-ceramic material, production and use thereof

The method produces a reshaped glass-ceramic article by forced reshaping of a flat green glass part during a ceramicizing process with temporarily lowered viscosity due to crystallization heat. To perform the forced reshaping economically the forced reshaping takes place in a continuous oven for ceramicizing and in an oven section in which the viscosity of the green glass part is temporarily lowered as a result of crystallization heat. An apparatus for performing the process is provided in the continuous oven including different active reshaping devices and/or a hollow mold. The method produces glass-ceramic articles with undamaged surfaces corresponding to surfaces produced during the making of the green glass part (smooth or structured, e.g. knobbed).

Method for reshaping glass-ceramic articles, apparatus for performing the method and glass-ceramic articles made thereby

The apparatus performs a forced reshaping of a flat green glass part during a ceramicizing process in which the viscosity of the glass is temporarily lowered due to crystallization heat. The apparatus includes a continuous furnace () for the ceramicizing process: a reshaping device (') provided with activating openings (); and vertically movable pressure-operated reshaping tools () arranged in the reshaping device (&#x2032;). The furnace () is provided with lateral openings () for temporarily connecting activating lines () to the activating openings () of the reshaping device (&#x2032;) in a sealed manner in order to operate the reshaping tools () by supplying pressurized air to the reshaping device or by producing a low pressure in the reshaping device (&#x2032;).

In the process for partially shaping, a glass/glass ceramic article () is held on a planar support plate () by suction. The glass/glass ceramic article is heated to soften it, so that it has a viscosity below 10dPa&#xb7;s. After the softening one or more shaping dies () is or are moved upward through an opening or respective openings () in the support plate to form raised regions in the softened glass/glass ceramic article (). The suction force is produced by a low pressure in a hollow compartment () below the support plate () and acts on the glass/glass ceramic article () by means of a gap (G) formed between each shaping die () and the support plate. Additional openings can be provided in the support plate and/or in one or more of the shaping dies to assist in applying the suction force to the glass/glass ceramic article. After solidification of the softened glass/glass-ceramic article the shaping die or dies () is or are withdrawn. Then the partially shaped glass/glass ceramic product is removed by compressed air and/or mechanically with lifting members (). An apparatus for performing this process is also described.

Process for partial shaping of flat glass or glass-ceramic articles and apparatus for performing same

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Ingelheim, Germany

Friedrich-Georg Schroeder