Method of Making Plate Glass.
Year: 1897

page_text: Date of Application, 24th Aug., 1897-Accepted, 2nd Oct., 1897
Method of Making Plate Glass.
I, CHARLES CORNELIUS HARTUNG, of 721 Olive Street, in the City of St. Louis,
State of Missouri, United States of America, Glass Worker, do hereby declare
the nature of this invention and in what manner the same is to be performed, to
be particularly described and ascertained in and by the following statement, and
illustrated in the accompanying drawings:-
:-
In the drawings, I have illustrated an apparatus for carrying my invention
into effect, which apparatus I have found to answer the purpose admirably, but,
it is obvious that there are other forms of apparatus which could, is advan-
tageously, be used, without in the least departing from the nature and principle
of my invention. Figure 1 of said drawings illustrates a top plan view of a
machine upon which my invention can be practiced. Figure 2 is a side eleva-
tional view. Figure 3 is an enlarged cross-sectional view of the roller.
Heretofore, the method most usually practiced in the manufacture of rolled
plate glass, contemplated the use of a bed plate or casting table and a roller, or
rollers which spread the molten glass out in sheet form on the table, after which
the glass was annealed. In practicing this old method of making plate glass,
the plate of glass would have an imperfect upper surface due, it is thought, to the
contraction of the molten glass after it has been spread on the casting table.
These imperfections existed in the form of waves or undulations on its upper
surface which extended longitudinally the sheet, making the glass of varying
thickness and rendering it less valuable than if such imperfections were not
present. These imperfections are always present in glass known in the market
as cathedral," "rough plate," "sky-light," and to my knowledge, although
many attempts have been made to remedy these defects in the manufacture of the
glass, I am not aware that such has ever been successfully accomplished.
"
I have discovered that if a rough, as distinguished from smooth roller be
employed to roll the glass, said glass after being rolled into plate form and per-
mitted to form its natural surface, this surface will, by reason of the heat still
contained in the body of the sheet of glass, become smooth and even, and thus not
present the imperfections to which I have referred. Briefly stated, therefore, my
invention may be said to consist in the method, herein described, of making plate
glass, first, by spreading the molten glass with a rough roller, permitting the
glass to form its own upper surface, making an even upper surface by reason of
the self-contained heat in the glass, and finally annealing the glass, whereby, a
smooth, even, and almost perfect surface is obtained.
In the drawings, A is the bed or casting table, and B the roller which prefer-
ably rests upon two straight fillets Caranged along the surface of the table. D is
a guide which rests upon the table in front of the roller and serves to limit the
width of the sheet of glass produced. At each end of the roller are hand wheels E,
by which it can be turned, and caused to roll along the table. The ends of the
roller are also provided with gears F which mesh with toothed racks arranged
along the sides of the table A. These racks and gears serve to keep the roller
correctly in position across the table.

page_text: So far as the above description goes, it relates to ordinary forms of glass rolling
machines, but my invention contemplates a roughened instead of a smooth roller.
The roughened roller used in connection with my invention is formed by roughen-
ing the surface in any manner, but preferably by corrugating the same longi-
tudinally. Glass rolled by such a roller temporarily bears the impression of the
roughened roller, but the self-contained heat in the newly rolled sheet causes the
upper surface of the glass to flow and seek its own proper level, thus obliterating
the impression made by the roughened roller. In practicing my invention, the
molten glass to be rolled is of the usual consistency, or heat.
In the experiments I have conducted relative to the practice of my invention,
I have found that rollers having varied degrees of roughness are to be used,
depending upon the thickness of the glass to be rolled. The heavier the glass,
the deeper may be the impressions, while with thinner glass, the impressions
should be shallow.
The resultant sheet of glass, made by the method herein described, and with
a single rough roller, has a surface which is smooth and even, compared with the
glass heretofore made. The longitudinally extending waves or undulations seem
to be broken at the surface, so that such waves are interrupted at nearly right
angles to their line of formation, and being thus broken up into short lengths,
as it might be called, when the upper surface of the glass forms its own surface
it will also correct any unevenness which otherwise would have been present in
the glass.
Having now particularly described and ascertained the nature of my invention
and in what manner the same is to be performed, I declare that what I claim is:
1. The method of making plate glass, the same consisting in spreading the
molten glass into plate form, cutting up, grooving, or impressing its upper surface
while it is being spread, and permitting the glass to form a smooth, even surface;
substantially as described.
2. The method of making plate glass, the same consisting in spreading the
molten glass into plate form, indenting, grooving, or forming an uneven upper
surface while the glass is still in a molten state, and permitting the glass to form
a smooth upper surface by reason of its self-contained heat; substantially as
described.
3. The method of making plate glass, the same consisting in spreading the
molten glass into plate form, indenting, cutting, or otherwise forming impressions
in its upper surface transversely the sheet, and permitting the glass to form its
own upper surface; substantially as described.
Dated the 24th day of August 1897