Improvements in Leers or Annealing Furnaces for Sheet or Plate Glass.
Year: 1892

page_text: Date of Aplication, 26th July, 1892-Accepted, 27th Aug., 1892
COMPLETE SPECIFICATION.
Improvements in Leers or Annealing Furnaces for Sheet or Plate
Glass.
I, JAMES WILLIAM BONTA, of Wayne, Delaware County, in the State of
Pennsylvania, one of the United States of America, Mechanical Engineer, do
hereby declare the nature of the said invention and in what manner the same is
to be performed, to be particularly described and ascertained in and by the following
statement:-
"2
The object of my invention is to so construct a leer or annealing furnace for
sheet or plate glass that the furnace bottom, when being heated to the required
temperature for receiving the rolled plate glass, will not "heave or expand
irregularly so as to throw the bottom off a true surface, thereby overcoming an
objection to ordinary furnace bottoms built up of solid material, and insuring the
preservation of the true level of the glass at all stages of annealing thus enabling
me to produce the original plate with the use of less glass in rolling and materially
reducing the subsequent grinding to obtain perfect surfaces.
In the accompanying drawings
Fig. 1, is a transverse sectional view of my improved leer or annealing furnace
on the line 1-2, Fig. 2.
Fig. 2, is a longitudinal sectional view.
Fig. 3, is a plan view of a portion of the table-supporting structure of the
leer; and,
Fig. 4, is a perspective view of one of the ventilated bricks of said supporting
structure.
In leers for annealing plate-glass a solid table is usually made, the top of the
table being composed of a layer of salmon bricks, and gas is introduced through
side openings until the furnace is heated to the desired temperature, the glass being
then placed directly upon the brick table, and the leer is then allowed to gradually
cool.
In furnaces or leers at present in use, in which the table or bottom of the
furnace is built up solid, portions of this solid mass of brick and mortar are inore
dense than other portions, hence the table, on heating the furnace, is caused to
expand unequally, and unevenness in the table therefore results, which unevenness
is reproduced in the plate which is being annealed, hence the original plate has to
be of considerably greater thickness than the finished plate to provide for grinding
off these irregularities.
I overcome this difficulty in the following manner, and am enabled to make the
original glass plate much thinner than heretofore owing to the special construction
of the furnace.
A, is the furnace having the table B, an arched roof and gas inlets a, and
provided with doors b, b, at each end in the ordinary manner.
B, is the table on which rests the glass to be annealed, this table being simply
a layer of salmon or soft bricks. Supporting the table is a row of bricks D, and
between these bricks are ventilating spaces e, which extend to the undersides of
the salmon bricks B. The bricks D, are made in the present instance as shown in
When these
Fig. 4, having ribs d. d. at each side, forming the air-channels c.
bricks are placed together, therefore, they form a floor as shown in Fig. 3, ventilated
throughout by the air channels or spaces c.
The bricks D, are supported by a series of foundation walls E, which are at
such a distance apart as to form air passage ways I, extending from the front to
the rear of the furnace and communicating with the air-spaces c, in the bricks D,
and also at one end with an outlet-flue I¹.

page_text: During the operation of the furnace, air it blown into the flues I, from nozzles s,
on a blast pipe S, which, in connection with the ventilating character of the
bricks D, serves to prevent any such heating of the supporting structure formed
by said bricks, as to cause the said structure either to "heave" or "sag," hence
the soft brick table B, mounted on the bricks D is kept at its proper and uniform
level during the annealing operation, and as unevenness in the glass plate is
thereby likewise prevented, I am enabled to roll said plate much thinner than
usual in the first instance, as the same margin does not have to be allowed for the
subsequent grinding.
In some instances the blast-pipe may be dispensed with and openings made in
the wall to admit air, and in this case the natural draft of the flue will be
sufficient.
It will be understood that I do not limit myself to the special construction of
leer shown, and to the precise form of ventilated bricks described, as the support
for the table may be made in any manner and of any material which will properly
ventilate the table.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed I declare that what I
claim is-
1. The combination in a leer or furnace for annealing sheet or plate-glass, of the
flat bed or table on which the sheet or plate of glass is laid, and a supporting
structure for said table having air spaces open only at the bottom, whereby the
supporting structure is ventilated without unduly cooling the table, substantially as
specified.
2. The combination in a leer or furnace for annealing sheet or plate glass, of the
flat bed or table on which the sheet or plate of glass is laid, and a supporting
structure for said table having air spaces open only at the bottom, and a foundation
having air-circulating passages communicating with said air-spaces, substantially
as specified.
3. The combination in a leer or furnace for annealing sheet or plate glass, of the
flat bed or table on which the sheet or plate of glass is laid, and a supporting
structure for said table having air spaces open only at the bottom, and a foundation
having air passages communicating with said air spaces, and air jet pipes and
outlets, whereby a circulation of air through said passages is effected, substantially
as specified.
4. The combination in a leer or furnace for annealing sheet or plate glass, of the
flat bed or table on which the sheet or plate of glass is laid, and a supporting
structure for said table composed of bricks having ribs at the ends, whereby, when
said bricks are assembled, air spaces are formed in the supporting structure,
substantially as specified.
Dated this 22nd day of July 1892.
DAY, DAVIES & HUNT,
321, High Holborn, London, W.C., Agents for the Applicant.