Improvements in the Manufacture of Sheet or Window Glass.
Year: 1889

page_text: Date of Application, 3rd Sept., 1889-Accepted, 5th Oct.. 1889
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Sheet or Window Glass.
We, MERRITT WASHINGTON GRISWOLD of 27 Beekman Street, Merchant, and
WALTER BUTLER ATTERBURY of the Cotton Exchange, Broker, both in the City and
State of New York in the United States of America, do hereby declare the nature
of our invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
This invention relates to an improved process for producing window or sheet glass
by the flattening of glass cylinders, and has for its object to obtain with greater
ease rapidity and economy a better quality of glass than by the methods heretofore
employed.
It consists in spreading open the divided glass cylinders as they become ductile in
the furnace by means of a blast of hot air steam or gas directed within the cylinder to
produce an expansion thereof and an unfolding of its divided edges as is hereinafter
more fully described and explained in the accompanying drawings which illustrate an
apparatus which may be employed in the process.
Figure 1 is a sectional plan view of a furnace of customary form adapted to the
flattening of glass cylinders, and a portion of the annealing lear which extends there-
from in line Z-Z of figure 3.
Figure 2 is a vertical radial section on an enlarged scale in line X-X of figure 1.
Figure 3 a transverse section in line Y-Y of figure 2; and
Figure 4 is a detached view in perspective, illustrating the cylinder of glass in
process of being opened out and flattened by the pneumatic pressure exerted upon its
inner face.
Similar letters indicate like parts in all of the figures.
A is a wheel or annular flattening table carrying a series of radially disposed
flattening stones B, B1, B2, and mounted upon and secured to a vertical spindle C to
revolve within a suitable circular furnace or oven D, having an annealing lear Di
extending therefrom. The whole being constructed and arranged substantially in the
manner well known to the art.
F is the receiving door.
G-G the doors through which access is had to the apparatus for expanding and
flattening the glass.
H-H sight holes provided on each side of said doors. I the finishing door, and J
the door for the lear.
K, (see fig. 2), represents a hot air or gas chamber formed transversely over the
furnace or oven D, above the doors G-G, and which is made to communicate with
said furnace or oven through passages k-k, formed in the walls thereof immediately
within each-door G, the opening of each of said passages into the furnace D being
made to correspond in size and to register with the outer doorway.
Within each of said openings, a tuyere L of any suitable refractory material is
fitted for the purpose of controlling and directing the flow of air, steam or gas from
the chamber K into the ends of the cylinder brought within range thereof. Each
tuyere is formed with a central opening m, adapted to be closed by a plug n, and
with a concentric annular opening p, and is rounded at its front end to fit with a close
joint into a counterpart circular seat R which will permit of a limited rotary move-
ment of the tuyere whereby it may be inclined to any direction or inclination of the
jets of air or gas issuing therefrom, to be changed more or less as may be required.
This may be accomplished by means of a wedged piece s, introduced under the rear
end of the tuyere as shown in fig. 2.

page_text: Each tuyere may also be moved to and from the table A, so as to admit of adjust-
ment with reference to the length of the glass cylinder to be brought between them
as shown by dotted line in fig. 2.
The chamber K is connected by means of a pipe T, with a hot blast stove or
furnace, an air-compressor, or a steam or gas generator of any suitable character, not
shown in the drawings and which need not herein be described; it being understood
that the air, steam or gas is preferably heated to a working temperature by any
suitable means before being admitted to the tuyeres L-L, and is supplied thereto
under sufficient pressure to produce a strong blast or jet when issuing from said
tuyeres into the furnace.
A narrow longitudinal slit or opening W, is formed between the upper chamber K
and the furnace to register with the slit in the glass cylinder E, brought and held
in range of the tuyeres L-L upon the revolving table A.
This narrow extended opening is controlled by a suitable valve W', which permits
it to be wholly closed. V-V represents vents formed through the top of the furnace
on each side of the tuyeres so as to allow of an escape of the inflowing jets and allow
of the expansion of the glass cylinder under the action of said jets.
In the operation of the apparatus a longitudinally slitted cylinder of glass E, is
inserted into the furnace or oven D, through the door F, and placed radially, with
the longitudinal slit therein uppermost, upon the proximate flattening stove B. The
wheel or table A is then turned to bring the cylinder into line opposite the
tuyeres LL, which are preferably so adjusted as that the mouth of each shall be
brought close to the proximate end of the cylinder. Ordinarily the cylinder after
being properly heated in the customary manner is spread open at this point by means
of tools or mechanical appliances which force apart the divided edges of the cylinder
and bear them down flat upon the stone.
In this method of flattening the glass, the outside of the cylinder being the hottest
because more immediately exposed to the direct beat in the furnace, and consequently
more mobile and yielding than the inner surface, is apt to become ridged, or corru-
gated or lumpy and in a measure therefore imperfect, as it is compressed in the
process of flattening out its convexity.
By our process the divided cylinder is prevented from falling or lapping down
and is gently and evenly spread open until it flattens down upon the stone by forcing
into it through the tuyeres L-I, strong blasts or currents of air, gas or superheated
steam preferably at a temperature which renders the inner concave surface softer and
more yielding than the outer convex surface, and said inner surface being extended as
it is straightened out, will be thereby drawn out into a perfectly true even and
beautiful smooth surface; whilst the outer surface will retain its original perfect
condition and be improved by the condensation of its particles.
The glass is truly and evenly flattened with great rapidity and with a resultant
finish superior to that produced by the ordinary methods. As occasion may require
an auxilliary current of air or gas may be introduced through the extended slit W,
directly over the open seam in the cylinder E, as the latter begins to open so as to
facilitate its expansion under the influence of the jets from the tuyeres. The glass
plate thus produced by the opening and flattening of the cylinder E, under a pressure
of air or gas is carried forward by the intermittent revolution of the wheel or table A,
to a point opposite the door I, where it is smoothed down by the customary appliances;
and it is finally brought opposite the end of the annealing lear D', into which it is
delivered as usual to be tempered and finished in the customary manner which it is
not necessary to describe.
It is evident that the expanding jets, blasts or currents of air, gas or super-heated
steam, may be introduced into the open ends of a slitted cylinder E, in a suitable oven
or furnace by means of tuyeres or nozzles of various descriptions, with or without
immediate connections with a hot air chamber K, as described; and that inflamable
or inflamed gases may be employed under pressure, instead of air, gases or steam,
heated wholly by external appliances.

page_text: Whilst it is preferable to employ in the process as described, blasts of air, gases, or
steam, heated to a temperature which will render the glass ductile and cause its inner
surface to be softer than the outer surface, we contemplate, when the cylinders are
already heated in the furnace to a proper temperature to render them sufficiently
ductile, opening and flattening them by jets or blasts of cold air or gases.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
:-
I. The within described process of flattening divided glass cylinders which consists
in subjecting them when ductile to a blast of air, gas or steam introduced into the
cylinder substantially in the manner specified.
II. The within described process of flattening divided glass cylinders which consists
in subjecting them to a sufficient degree of heat to make them plastic and then sub-
mitting them to a blast of air or gas forced into the cylinder under a pressure
sufficient to produce a separation or divergence of the opposite sides of the ductile
cylinder.
III. The process of softening the inner concave surface of a divided glass cylinder,
which consists in heating the same by means of a blast of air, gas or dry steam
applied directly thereto with power sufficient to produce a separation and divergence
of the opposite sides of the ductile cylinder substantially in the manner and for the
purpose herein set forth.
Dated this Eighth dow of Inly 1880
MERRITT WASHINGTON GRISWOLD.
WALTER BUTLER ATTERBURY.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicants.