Heat transfer method in glass sheet bending oven and a bending o

Details Heat transfer method in glass sheet bending oven and a bending o Heat transfer method in glass sheet bending oven and a bending o

1998-08-18

1999-11-02

Chin, Peter

Glass manufacturing

Processes

Reshaping or surface deformation of glass preform

65106, 65111, 65118, 65273, 65290, 65291, 65307, 65361, 34430, 34629, 432 77, 432 78, 432120, 432144, 432145, 432152, C03B 23023

Patent

active

059748338

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The invention relates to a heat transfer method and an applicable glass bending furnace having a top array of successive heating sections and a bottom array of successive cooling sections in which air heated by hot bent glass sheets is drawn from the cooling sections and blasted into the heating sections.


BACKGROUND OF THE INVENTION

Previously known from the Finnish patent 68390 is intensification of heat transfer in a double-decker glass bending furnace, where heat transfer is effected vertically between sections one on top of another by means of radiation and gravitational convection. The bottom of the mold carrier wagons is open enabling radiation and convection from the hot glass sheet on the bottom track section to the colder glass sheet on the top track section.
Further, a method to intensify heat transfer is known from patent FI-81331, where in comparison with the above solution, fans are installed to increase heat transfer from the bottom track section to the top track section.
Not even the last mentioned solution has turned out effective enough, because it works effectively only for a few seconds when the mold carrier wagons have reached a new position. There is then during this short moment enough difference of temperature for significant heat transfer. However, since the mold carrying wagons always stay for a time span of 1.5-3 minutes in a section before they are shifted over to the next section, the use of fans is quite useless.


SUMMARY OF THE INVENTION

A method and bending furnace as per this invention offer a significant improvement of heat transfer and significantly longer lasting heat transfer per each cycle.
According to the invention, glass sheets on bending molds in mold carrying wagons are conveyed through the heating sections and then through the cooling sections by mold carrying wagons. Hot air produced by the hot bent glass sheets is drawn from the cooling sections and then blasted in a direction opposite the direction of travel of the mold carrying wagons to colder glass sheets in the heating sections. In particular, the heated air is blasted into a heating section which precedes the heating section directly above the cooling section from which the hot air is drawn by means of air channels and fans. A return air channel system is used to return air from a given heating section into the cooling section directly below the heating section or adjacent thereto.
By means of the method and bending furnace of this invention the transfer of heat from the bottom track section to the top track section and the glass therein is instensified to a considerable extent. A substantial portion of intensification is based on the increased available temperature difference between the bottom track glass and the top track glass, to which air is blasted from the bottom track section.


BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention is disclosed with reference to the enclosed drawing, where
FIG. 1 shows a bending furnace schematically in a side view; and
FIG. 2 shows a perspective view of successive bending furnace sections with bottom track and top track.
The arrows in the schematic view of FIG. 1 show the travel direction of mold carrying wagons and the glass sheets upon them in furnace 1. For instance, on the top track there are six sections 2, where the glass sheet is heated, and a section, where bending takes place and where the mold carrying wagon is lowered onto the bottom track. There are, for instance, on the bottom track six cooling sections 3. In the figure two mold carrying wagons 13 are illustrated by way of example.
FIG. 2 is a view of some sections 6 and 7, which are individually-built, successive segments joined together to form a successive furnace. There is a floor 4 between the top track and the bottom track. On both sides of sections 6,7 there are wheels 11 partly embedded in insulation 10 and fastened by bearings to roll for conveyance of the mold carrying wagons 13. At least as one wagon end, the mold carrying wagons 13 have an insulat

REFERENCES:
patent: 3431095 (1969-03-01), Ross
patent: 3711265 (1973-01-01), Jadin
patent: 4497645 (1985-02-01), Peltonen
patent: 4755204 (1988-07-01), Boardman et al.
patent: 4986842 (1991-01-01), Peltonen
patent: 5066320 (1991-11-01), Lehto et al.
patent: 5292355 (1994-03-01), Nikander
patent: 5472469 (1995-12-01), Yli-Vakkuri et al.
patent: 5679123 (1997-10-01), Bennett et al.

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