Glass manufacturing – Processes – Reshaping or surface deformation of glass preform
Reexamination Certificate
1999-05-20
2001-10-16
Colaianni, Michael P. (Department: 1731)
Glass manufacturing
Processes
Reshaping or surface deformation of glass preform
C065S107000, C065S110000, C065S034000, C065S036000, C065S044000, C065S045000, C065S054000, C065S067000, C065S068000, C065S086000, C065S087000, C065S093000
Reexamination Certificate
active
06301932
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to glass articles and forming, and particularly to a method for forming glass envelopes, i.e., glass articles, possessing enclosed internal channels, for use in light emitting neon display devices.
DESCRIPTION OF THE RELATED ART
Neon lighting devices are disclosed in U.S. Pat. No. 4,584,501 (Cocks et al.), U.S. Pat. No. 4,990,826 (Cocks et al.), U.S. Pat. No. 5,036,243 (Cocks et al.). Generally, these patents disclose multifaceted lighting devices comprising glass or other vitreous plates which are hermetically sealed together to form a device with internally enclosed channels. These channels are thereafter evacuated and backfilled with an inert gas such as neon and thereafter ionized through the provision of a series of electrodes.
Generally, the method for forming the glass component of these prior art neon lighting devices involves cutting channels in a bottom glass plate followed by hermetically sealing, via the use of a glass frit, a glass top plate to this channeled glass bottom plate. Various methods are used to cut the channels into the bottom glass plate including grinding, etching and sand blasting through an adhesive rubberized mask exhibiting a pattern identical in shape to the desired channel pattern. The result of this cutting and subsequent fritting is that formation of the glass component of these lighting devices is an expensive and inefficient process with the resultant glass component being too heavy for use in those applications where weight is a concern, e.g., automotive applications.
Other more recent flat type lighting devices are disclosed in U.S. Pat. Nos. 5,041,762 (Hartai), 5,220,249 (Tsukada) and 5,223,262 (Lynn et al.). However, each of these references produces the glass body in generally the same manner, two glass plates fritted or sealed together. For example, Tsukada discloses a pair of transparent plates assembled and sealed together by a solder glass with a groove formed on the surface of one of the transparent glass plates thereby forming a discharge channel.
Recently, an improved method for forming glass bodies for use as discharge lighting devices has been disclosed in U.S. Pat. App., Ser. No. 08/634, 485 (Allen et al.); co-assigned to the instant assignee, and herein incorporated by reference. Briefly, this method, as illustrated in
FIG. 1
involves two, separately delivered and deposited, molten glass ribbons, i.e., a sealing ribbon laid over the top of the already deposited channel-forming ribbon. This method involves the use of separate glass delivery systems each having its own set of glass delivery rollers and associated glass gobs. For very thin products/thin ribbons, the difficulty with this method is that in order to maintain a time-efficient process, the rollers must be spaced very close together and run a very high speed, e.g. rollers spaced 12 in. apart and moved at a speed of about 17″/sec. As such, any additional processing which must be done to the first ribbon must be accomplished in a very short, unmanageable period of time, i.e., before the delivery and deposit of the second/sealing ribbon, thus making the process somewhat inflexible. For instance, additional processing such as, the application and release of a vacuum to the underside of the ribbon to enhance conformance and/or the application and release of a vacuum to create and maintain pockets in the channel-forming ribbon for later delivery of air to support the sealing ribbon. It therefore became necessary to design a process which is far less dependent upon the roller spacing, thus allowing greater flexibility.
As such, the principal objective of the present method is to provide for an improved, more flexible method of forming the glass component for use in neon lighting devices; one which is simpler, more efficient, and less dependent on roller spacing than the prior art multiple ribbon method.
SUMMARY OF THE INVENTION
Accordingly, the present invention for forming glass articles containing internally enclosed channels comprises the following steps: (a) delivering and depositing a first length of a molten glass ribbon to a surface of a mold having a mold cavity possessing at least one channel-forming groove and a peripheral surface, wherein the first length of ribbon overlies the mold cavity and the peripheral surface, (b) causing the first length of ribbon to substantially conform to the contour of the mold cavity thereby forming at least one channel in the first length, (c) delivering and depositing a second length of the molten glass ribbon to the exposed surface of the earlier deposited first length of molten glass ribbon.
The viscosity of the molten glass ribbon at delivery is between about 1000 to 5000 poise so that the following is achieved: (1) the second length of the molten glass ribbon bridges, but does not sag into complete contact with the entire surface of the channel of the first length of the molten glass ribbon; and, (2) a hermetic seal is formed between the first and second lengths of the molten glass ribbon wherever they contact.
REFERENCES:
patent: 805610 (1905-11-01), White
patent: 3347652 (1967-10-01), Giffen
Allen Stephen R.
Anderson James G.
Kiphut Robert J.
Trentelman Jackson P.
Colaianni Michael P.
Corning Incorporated
Gheorghiu Anca C.
Peterson Milton M.
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