Heating – Work chamber having heating means – Tortuous – branched or baffled heating flue means within or...
Patent
1998-02-20
2000-01-18
Paschall, Mark
Heating
Work chamber having heating means
Tortuous, branched or baffled heating flue means within or...
445 45, 445 66, F27B 516
Patent
active
060152885
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to ovens for the heat treatment of glass articles and, more specifically, to tunnel type ovens for continuous treatment of cathode ray tubes at the same time as gases contained within the tube are evacuated, commonly referred to as "exhaust ovens".
2. Description of the Related Art
One example of an exhaust oven for this purpose is described in U.S. Pat. No. 4,752,268.
The heating and cooling of the shaped glass envelope forming the tube to minimise stresses therein and its evacuation which subjects the walls to substantial external pressure is a critical operation. The demand for larger and flatter cathode ray tubes, particularly for domestic high definition "flat screen" television receivers, has increased the processing problems and the need for ovens giving economical production and minimum damage or wastage of these high value components.
The object of the invention is to provide an exhaust oven for cathode ray tubes which is particularly effective and reliable in operation to provide economical and consistent production.
SUMMARY OF THE INVENTION
An exhaust oven for heat treating and simultaneously evacuating cathode ray tubes includes a tunnel structure with a through passageway and temperature control apparatus for providing regulated heating and/or cooling of the atmosphere in one or more longitudinal zones of the passageway. The oven also includes apparatus for conveying the tubes along the passageway and exhaust ducts operatively connected to the necks of the tubes during conveyance to evacuate gases therefrom. Baffles within at least one of the longitudinal zones of the passageway circulate the atmosphere about the exterior of the tubes. The baffles include at least one inlet directing a flow of atmosphere to impinge onto the face of the screen panel of each tube and one or more outlets in adjacent spaced relationship to side edges of said panel and/or to the neck of the tube for exit of the flow of atmosphere from the baffles.
According to one aspect of the invention there is provided an exhaust oven for heat treating and simultaneously evacuating cathode ray tubes as defined by claim 1 of the appended claims.
According to another aspect,the invention comprises a cathode ray tube as defined by claim 10 hereof.
BRIEF DESCRIPTION OF THE DRAWINGS
An example of the invention is now more particularly described with reference to the accompanying drawings, wherein:
FIG. 1 is a lateral cross-section of a heating zone of a CRT exhaust oven,
FIG. 2 is a longitudinal section of part of said zone on line 2--2 of FIG. 1, and
FIG. 3 is a diagrammatic plan view of the oven and its transport means.
The exhaust oven comprises a tunnel structure 10 having outer structural walls 12 lined with insulating material 14 to define a through passage 16 which is rectangular in lateral section.
DETAILED DESCRIPTION OF THE INVENTION
Transport means comprises a track 18 having vertically spaced upper and lower guide rails 20, 22 immediately below and to one side of structure 10 and extending in a continuous loop from the tunnel exit 24 round to the tunnel entrance 26 (FIG. 3). There are loading and unloading stations 28, 30 along the part of track 18 outside structure 10.
A train of vacuum carts 32 runs on track 18, each cart being provided with an upwardly projecting support 34 which projects into the bottom part of passage 16 through a longitudinal slot 36 in the floor of structure 10. Each support 34 incorporates an exhaust duct and is operatively connected to the neck 38 of the glass envelope of a cathode ray tube (CRT) 40 so that the latter is transported along passage 16 by movement of the cart with its large area screen panel 42 directed upwards and maintained generally centrally of the passage lower half substantially spaced from its walls. Each tube is further supported and located by a respective cage 44.
During transport through the oven, vacuum carts 32 are operated automatically in known manner to exhaust the interior of each
REFERENCES:
patent: 3884667 (1975-05-01), Schraven
patent: 4028052 (1977-06-01), Verhoeven et al.
patent: 4752268 (1988-06-01), Kataoka et al.
patent: 4979919 (1990-12-01), Toyama
patent: 5201682 (1993-04-01), Nakagawa et al.
patent: 5588830 (1996-12-01), Josefsson et al.
Paschall Mark
Stein Atkinson Stordy Limited
Wilson Gregory A.
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