Glass manufacturing – Processes – Utilizing parting or lubricating layer
Reexamination Certificate
2000-02-25
2003-01-14
Colaianni, Michael (Department: 1731)
Glass manufacturing
Processes
Utilizing parting or lubricating layer
C065S025100, C065S025400, C065S029150, C065S110000, C065S182100, C065S182200, C198S493000, C198S721000, C406S070000, C406S088000, C266S103000, C266S111000, C266S274000
Reexamination Certificate
active
06505483
ABSTRACT:
This invention relates generally to glass sheets and more particularly to apparatus for conveying heated glass sheets to glass forming stations.
The invention is particularly applicable to and will be described with specific reference to a transport system in which glass sheets are conveyed from a furnace to a female ring mold of a press bending station in an integrated manner therewith. However, the invention in its broader sense has application to the conveyance of glass sheets throughout the stages of the glass forming or treating process and in a yet broader sense may be used for conveying any thin sheets of material.
All of the above cited patents do not, per se, form any part of the present invention. They are referenced and incorporated herein so that details relating to known methods and apparatus of bending or forming glass sheets and known strip flotation techniques need not be further described or set forth in detail in the Detailed Description of the Invention.
BACKGROUND
Producing panes of glass for automotive vehicles and the like is a specialized, sophisticated and complex manufacturing process which is constantly subjected to increasingly stringent requirements. The glass must, of course, satisfy numerous safety requirements. Automotive styling trends now require complicated glass curvature shapes, all of which must be made free from surface defects and of high optical quality to permit a distortion free view through the window even though the surfaces can have curvatures in two directions perpendicular to one another. Demands for vehicle weight reduction and increased fuel economy have consistently driven the thickness of the sheet down from traditional levels for laminated glass products such as automotive windshields of about 5 millimeters (two sheets of glass of 2.2-2.3 mm in thickness) to levels around 3 millimeters (two sheets of glass 1.6 mm or less in thickness). Similarly, heat strengthened and/or tempered glass sheets used in, for example, automotive back lights and sidelights are now produced at thicknesses well below 3 mm. Finally, production demands require the glass be produced at relatively short cycle times.
One conventional way to form glass sheet shapes and to which this invention is directed in its preferred embodiment is to form a glass sheet into its configuration by a press bending system in which the pressing step occurs outside the furnace. This system will produce a continuous rapid succession of glass sheets provided that each step in the process can occur rapidly. It has been found to be increasingly difficult to manufacture thin glass sheets of complex shape free of optical distortion. While optical distortion may occur during shaping or bonding, it has been determined that heat-softened glass sheets, especially thin sheets, are susceptible to both distortion and loss of shape from a variety of causes while supported on conventional rollers used in the glass forming process. More particularly, the glass sheets are believed most highly susceptible to distortion when they are transferred by conveyor rollers from the exit end of the furnace to the female ring mold member of a press bending station. The conveyor rollers in this section of the process have an inner, hollow, stationary core member and an outer, flexible, load-carrying sleeve rotatable about the inner core. The conveyor rolls are disclosed and described in U.S. Pat. No. 3,905,794 incorporated herein by reference. The rolls are specially sized and driven so as to be integrated with the female mold ring configuration such as shown in
FIG. 10
of the ′922 patent. Reference can be had to U.S. Pat. No. 5,004,492 for a further description.
It has long been known to float metal strip and the like produced in continuous strip lines by jet streams of gas emitted from pressure pads which produced specially configured jets. A description of the theory and a discussion of pertinent prior art pressure pad designs is set forth in the ′329 patent, which patent including the references incorporated therein by reference are likewise incorporated herein by reference. Specifically, a prior art pressure pad design illustrated in the ′329 patent and especially adapted for heating, supporting and conveying thin and thick metal strip is utilized in this invention. As a general observation, suspending a continuous, moving strip of rigid material (typically metal) is significantly different than suspending discrete, moving items having a plastic mass, substance or consistency that is semi-viscous and easily deformable and are literally ejected, serially, from one work station to another. As a more specific observation, pressure pad configurations used in continuous strip lines and the like are generally orientated transverse to the direction of strip travel and spaced from one another to allow heated gases to escape after they have impinged and supported the strip and effected heat transfer therewith, i.e., spent.
Air flotation systems have long been used in glass manufacturing processes where the glass in its semi-viscous, heat softened condition is transported and shaped. In glass systems utilizing an external bending press, air distribution systems have long been used in the male press mold to bend the glass sheet and retain it under vacuum for transfer to subsequent stations such as shown by the glass patents incorporated herein by reference. Air flotation systems have also been used to support glass sheets conveyed in the processing line and reference can be had to U.S. Pat. Nos. 4,432,782 to Seymour; 4,612,031 to Bennett et al.; 5,009,695 to Kuster et al.; and, 5,078,776 to Kajii et al. These systems generally illustrate a plurality of apertures formed in or extending from metal surfaces configured to the desired cross-sectional shape of the sheet. The sheets are floated on the individual jet streams emanating from the apertures, i.e., orifices. For reasons discussed in the Detailed Description that follows, it is not desired to use a plurality of jet orifices to transfer the glass sheets.
SUMMARY OF THE INVENTION
Accordingly, it is a principal object of the present invention to provide a gas flotation system for transporting glass sheets, for example, from one station to another in a glass processing system.
This object along with other features of the invention is achieved in a transfer station for conveying glass sheets traveling in a given direction. The transfer station includes a plurality of pressure pads with each pad having a pair of longitudinally-extending slot nozzles transversely spaced from each other by a baffle plate. The slot nozzles are angled to oppose one another and the baffle plate provides a static surface area supporting the overlying sheet surfaces whereby the glass sheets are supported in the transfer station. Significantly, the static pressure area provides a heat transfer area to maintain the glass sheets at a desired uniform temperature by controlling the temperature of the gases in a plenum directing a gas under pressure at a set temperature to the pressure pads.
In accordance with another aspect of the invention, the travel of the glass sheets are in a longitudinal direction. Particularly, when the invention is used to float thin glass sheets or sheets that are to be formed, the direction of flow of the glass sheets is along a longitudinal work flow axis. The slotted nozzles are parallel one another and generally aligned with, but at an angle to the longitudinally-extending work flow axis so that any specific glass surface area is not constantly exposed to jet impingement as the glass sheets travel through the glass processing system. Constant gas impingement of any surface area has the potential for optically distorting the glass sheet, which could become significant for thin glass sheets.
In accordance with an important aspect of the invention, at least certain pressure pads have an angled edge transversely extending jet nozzle adjacent their longitudinal ends so that the gas emanating from the edge jet nozzle is effective to transition the
Dunifon Thomas A.
Hoetzl Max
Rozevink Larry L.
Colaianni Michael
Nawalanic Frank J.
Schurr Donald A.
Surface Combustion, Inc.
LandOfFree
Glass transportation system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Glass transportation system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Glass transportation system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3026903