Overflow downdrawn glass forming method and apparatus

Patent No. 6,889,526

Issued: May 10, 2005
Filed: August 8, 2002

Inventor: Pitbladdo; Richard B. (6949 Bentgrass Dr., Naples, FL 34113)


One embodiment of the present invention is an improved sheet glass forming apparatus. In another embodiment, a precise thermal control system redistributes the flow of molten glass at the weirs to counteract the degradation of the sheet forming apparatus which inevitably occurs during manufacturing. In yet another embodiment, the invention introduces a counteracting force to the stresses on the trough in a manner such that the thermal creep which inevitably occurs has a minimum impact on the glass flow characteristics of the forming trough. Another embodiment creates a variable external cross-section which provides hydraulic stresses that are in opposition to the surface tension and body force stresses and thus, reduces the influence of surface tension and body forces. In an alternative embodiment, the glass is preferentially cooled across its width to create forming stresses during solidification, which ensures that the glass sheet drawn is inherently flat. In an additional embodiment, the internal pressure is adjusted in each of the major components of the forming apparatus such that the pressure difference across any leakage path to the forming zone is essentially zero. Therefore, air leakage in the apparatus is minimized even though the cracks and openings exist during initial operation and develop during manufacturing.

This application claims an invention that was disclosed in one of the following provisional applications:

1) Provisional Application No. 60/310,989, filed Aug. 8, 2001, entitled "SHEET GLASS FORMING DEVICE";
2) Provisional Application No. 60/316,676, filed Aug. 31, 2001, entitled "SHEET GLASS FORMING DEVICE";
3) Provisional Application No. 60/318,726, filed Sep. 12, 2001, entitled "SHEET GLASS FORMING APPARATUS";
4) Provisional Application No. 60/318,808, filed Sep. 13, 2001, entitled "SHEET GLASS FORMING APPARATUS";
5) Provisional Application No. 60/345,464, filed Jan. 3, 2002, entitled "SHEET GLASS FORMING APPARATUS"; and
6) Provisional Application No. 60/345,465, filed Jan. 3, 2002, entitled "SHEET GLASS FORMING APPARATUS".

The benefit under 35 USC 119(e) of the United States provisional applications is hereby claimed, and the aforementioned applications are hereby incorporated herein by reference.

This application claims an invention related to U.S. application Ser. No. 09/851,627, filed May 9, 2001, entitled "SHEET GLASS FORMING APPARATUS". The aforementioned application is hereby incorporated by reference.


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