Improved Process and Apparatus for the Production of Thin Sheets of Mirror Glass.
Year: 1899

page_text: Date of Application, 15th Mar., 1899
Complate Specification Left, 9th Jan., 1900-Accepted, 17th Feb., 1900
PROVISIONAL SPECIFICATION.
Improved Process and Apparatus for the Production of Thin Sheets of
Mirror Glass.
I, ANDRÉ DE MORIAMÉ, Engineer, of Ligny, Belgium, do hereby declare the
nature of this invention to be as follows:-
This invertion for an improved process and apparatus for the production of
thin sheets of mirror glass has for its object to provide a process and apparatus for
the production, hitherto unsuccessfully attempted, of thin sheets of cast glass with
perfectly even surfaces throughout, that can be worn away evenly all over in the
smoothing process, and thus form finished sheets of mirror glass of uniform.
strength and thickness, as distinguished from the productions of the kind
hitherto attainable, which, in consequence of the distortion of the thin plates, are
not only unequal when smoothed or polished, but in many places worn right
through, so that the production of thin sheets of cast mirror glass has up to the
present time been dependent upon obtaining a suitable sheet of glass exceptionally
and by chance, whereas the new process renders it possible to produce the finest
finished articles in large quantities without any limitation or exception.
In the accompanying two sheets of illustrative drawings:-
Fig. 1 is a longitudinal section of a molting furnace constructed according to
this invention,
Fig. 2 a cross section and
Fig. 3 a horizontal section of the same.
Fig. 4 is a horizontal section of an annealing furnace composed of two parallel
furnace bodies with adjoining cooling gallery.
Fig. 5 a longitudinal section of the one and
Fig. 6 a similar section of the other furnace body of the annealing furnace.
Fig. 7 being a cross section of the same at the point where the furnace bottoms
are carried over from the one into the other.
Fig. 8 is a cross section and
Fig. 9 a plan of the polishing apparatus.
The melting furnace a differs from those hitherto used in casting mirror glass
by the construction at each of its ends of a preliminary annealing furnace & the
advantage of which is that the melting furnace can be constantly kept at a high
temperature for melting and refining the molten glass in the melting pots c without
any interruption in the heating for the preliminary annealing of the cast glass
to be rolled out; the same heating gases passing from the melting furnace over
the preliminary annealing furnaces likewise keep the same steadily at the necessary
temperature for the preliminary annealing, whereby the furnace is kept in con-
tinuous action and consequently an uninterrupted casting and rolling out of plates
of mirror glass is rendered possible. The process will be readily understood by
reference to the drawing.
In the present example, provision is made for 36 melting pots c being placed
in the furnace. These pots can be put in and taken out in rows of G through the

page_text: <
side openings d whilst the preliminary annealing furnaces b are arranged to re-
ceive 4 melting pots and are conveyed through the flue e which also conveys the
furnace heating gases. The further arrangement of the gas flues is of no conse-
quence here and therefore not more fully explained.
The furnace is worked simultaneously at both sides in the following manner:
The two outermost melting pots of the first row in the melting furnace a are con-
veyed into the preliminary annealing furnace b, so that two melting pot places
in the melting furnace and two in the preliminary annealing surface are free.
Whilst now the two further melting pots, viz., the third and the fourth have been
taken out at the corresponding sides of the melting furnace and have taken up
the two empty places in the preliminary heating furnace, the two first one and two
are sufficiently cooled for casting and are now taken out of the preliminary anneal-
ing furnace, placed over the rolling table in front of the annealing furnace, and
emptied. At the same time, the two last melting pots, five and six of the first
row have been conveyed from the melting furnace into the preliminary anneal-
ing furnace, the first row of melting pot places being thus now free, so that, whilst
the melting pots three and four are conveyed from the preliminary annealing fur-
nace to the rolling table they are partially cooled, whereas the two first are again
filled with material and conveyed into the melting furnace in the place of melting
pots five and six, the interchanging of melting pots for each row and from one
Tow to another thus rendered possible occurring without interruption and con-
tinuing as long as may be desired, without any alteration of temperature for the
furnace, whereby, the alternate cooling and re-heating and the loss of heat result-
ing therefrom which make the working of the melting pots so tedious and expen-
sive are entirely avoided.
The plates rolled out thin on the casting table, arranged in front of the anneal-
ing furnace, but not shown in the drawing, are now conveyed in the order in
which they were made, and at the same continuous rate, for further treatment,
according to the special process described below,
ing furnace also hereinafter referred to.
The annealing furnace is distinguished from
constructed without a bottom this being repla
veying a certain number of furnace bottom p
interior of the furnace. For this purpose, tw
suitably constructed anneal-
dinary "Carcaisen" in being
à means of transport for con-
ich describe a circuit in the
lel running furnace bodies f
and
g are connected at the ends by two "bridging over bodies and i, so that
the furnace forms a four cornered gallery, which with the side i adjoins the final
cooling gallery k. As means for conveying the bottom plates or parts which
carry the thin rolled out sheets of mirror glass, any preferred arrangements may
be adopted, and in the present example, the known "Bievez" changing rails m
in combination with suitable sets of rollers are selected.
At the end of the annealing furnace body fan opening o is formed for intro-
ducing the evenly rolled out sheet glass pushed away from the casting table, on
to the first bottom plate 1. The plate is then brought by means of a stream of
heated gas, conveyed through a flue p, to a temperature which completely softens
the sheet of glass but does not melt it again, so that the sheet lies completely flat,
throughout on the fire-proof stone bottom (previously heated to the same tempera-
ture) which is quite even, and "levels out" in such a manner that there is not
the slightest unevenness, that is to say, the sheet is now quite flat throughout its
surface.
As soon as a fresh sheet is rolled out and ready to be introduced, the transport-
ing rails are set in motion in the known manner and the furnace bottom with the
glass sheet pushed rather more than one length towards the suitably cool part of
the furnace and there kept until the next following sheet is conveyed to its place
and the first simultaneously carried along a length further and placed in a corre-
spondingly cooler position and so on until the first bottom plate comes on to the
set of rollers of the "bridging over" piece i and is conveyed by this means to the
entrance of the cooling gallery k.

page_text: Here the glass sheet is already stiffened and can be removed from the bottom
plate without hesitation and taken direct on to the changing bars or rails of the
gallery and carried along, until completely cooled, to the polishing apparatus.
During this operation the bottom plate is carried back into the furnace body g
on to the set of rollers n of the "bridging over" piece where it is heated' again
to the high original temperature by means of a stream of heated gas introduced
through the flue g and conveyed back to the opening o for the purpose of renewing
the described circuit, from which it is easy to perceive that the number of bottom
plates introduced into the circuit of the annealing furnace or rather surface fur-
nace is the same as that of the melting furnace pots set in action.
The glass sheets now completely cooled and entirely even throughout their sur-
face would, on account of the weakness or in other words the thinness of the glass,
be in danger of being broken in the ordinary polishing process owing to the pres-
Bure being too great by reason of the weight of the polishing frame rotating on
them, whereas, by the new polishing process, all breakage is avoided, this being
due to the fact that the sheets of mirror glass are not polished on the upper sur-
face by means of the ordinary polishing apparatus but are firmly cemented for
this purpose to the under surfaces of polishing plates r, guided freely in a vertical
direction in a fixed frame and set in rotation around their axes by means of the
polishing table rotating below and in consequence of the combined effect of these
two movements are very rapidly and finely polished.
16
32
The fixed frame is composed of the four uprights u placed around the table and
connected by cross bars on which are eyes 10 serving to receive the pins &
of the rotating plates r and keep them in position, whilst the table & rotated on a
vertical shaft in a vertical bearing by means of suitable bevel wheels rotates
the plates around their axes. Instead of only a single large sheet of glass,
several small sheets can be polished by means of suitably formed plates.
Dated this 15th day of Verch 1800
improved Process and Apparatus for the Froduction of Thin sheets of
Mirror Glass.
I, ANDRÉ DE MORIAMÉ, Engineer, of Ligny, Belgium, 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:-
This invention for an improved process and apparatus for the production of
thin sheets of mirror glass has for its object to provide a furnace and apparatus for
the production, hitherto unsuccessfully attempted, of thin sheets of cast glass with
perfectly even surfaces throughout, that can be worn away evenly all over in the
sinoothing process, and thus form finished sheets of mirror glass of uniform
strength and thickness, as distinguished from the productions of the kind hitherto
attainable, which, in consequence of the distortion of the thin plates, are not
only unequal when smoothed or polished, but in many places worn right through,
so that the production of thin sheets of cast mirror glass has up to the present time
been dependent upon obtaining a suitable sheet of glass exceptionally and by
chance, whereas the new process renders it possible to produce the finest finished
articles in large quantities without any limitation or exception.
In the two sheets of illustrative drawings filed with the Provisional Specifi-
cation:
-

page_text: Fig. 1 is a longitudinal section of a melting furnace constructed according to
this invention,
Fig. 2 a cross section and
Fig. 3 a horizontal section of the same.
Fig. 4 is a horizontal section of an annealing furnace composed of two parallel
furnace bodies with adjoining cooling gallery.
Fig. 5 is a longitudinal section of the one and
Fig. 6 a similar section of the other furnace body of the annealing furnace.
Fig. 7 being a cross section of the same at the point where the furnace bottoms
are carried over from the one into the other.
Fig. 8 is a cross section and
Fig. 9 a plan of the polishing apparatus.
The melting furnace a differs from those hitherto used in casting mirror glass
by the construction at each of its ends of a preliminary annealing furnace 6 the
advantage of which is that the melting furnace can be constantly kept at a high
temperature for melting and refining the molten glass in the melting pots c without
any interruption in the heating for the preliminary annealing of the cast glass
to be rolled out; the same heating gases passing from the melting furnace over
the preliminary annealing furnaces likewise keep the same steadily at the necessary
temperature for the preliminary annealing, whereby the furnace is kept in in con-
tinuous action and consequently an uninterrupted casting and rolling out of plates
or mirror glass is rendered possible. The process will be readily understood by
reference to the drawing.
In the present example; provision is made for 36 melting pots c being placed
in the furnace. These pots can be put in and taken out in rows of 6 through the
side openings d whilst the preliminary annealing furnaces are arranged to re-
ceive 4 melting pots and are conveyed through the flue e which also conveys the
furnace heating gases. The further arrangement of the gas flues is of no conse-
quence here and therefore not more fully explained.
The furnace is worked simultaneously at both sides in the following manner:
The two outermost melting pots of the first row in the melting furnace a are con-
veyed into the preliminary annealing furnace b, so that two melting pot places
in the melting furnace and two in the preliminary annealing furnace are free
Whilst now the two further melting pots, riz., the third and the fourth have been
taken out at the corresponding sides of the melting furnace and have taken up
the two empty places in the preliminary heating furnace, the two first one and two
are sufficiently cooled for casting and are now taken out of the preliminary anneal-
ing furnace, placed over the rolling table in front of the annealing furnace, and
emptied. At the same time, the two last melting pots, five and six of the first
row have been conveyed from the melting furnace into the preliminary anneal-
ing furnace, the first row of melting pot places being thus now free, so that, whilst
the melting pots three and four are conveyed from the preliminary annealing fur-
nace to the rolling table they are partially cooled, whereas the two first are again
filled with material and conveyed into the melting furnace in the place of melting
pots five and six, the interchanging of melting pots for each row and from one
row to another thus rendered possible occurring without interruption and con-
tinuing as long as may be desired, without any alteration of temperature for the
furnace, whereby, the alternate cooling and re-heating and the loss of heat result-
ing therefrom which make the working of the melting pots so tedious and expen-
sive are entirely avoided.
The plates rolled out thin on the casting table, arranged in front of the anneal-
ing furnace, but not shown in the drawing, are now conveyed in the order in
which they were made, and at the same continuous rate, for further treatment,
according to the special process described below, to a suitably constructed anneal-
ing furnace also hereinafter referred to.
The annealing furnace is distinguished from the ordinary "Carcaisen" in being
constructed without a bottom this being replaced by a means of transport for con-

page_text: "
veying a certain number of furnace bottom plates which describe a circuit in the
interior of the furnace. For this purpose, two parallel running furnace bodies f
and y are connected at the ends by two "bridging over bodies and i, so that
the furnace forms a four cornered gallery, which with the side i adjoins the final
cooling gallery k. As means for conveying the bottom plates or parts 7 which
carry the thin rolled out sheets of mirror glass, any preferred arrangements may
be adopted, and in the present example, the known "Bievez" changing rails m
in combination with suitable sets of rollers are selected.
At the end of the annealing furnace bodyf an opening o is formed for intro-
ducing the evenly rolled out sheet glass pushed away from the casting table, on
to the first bottom plate . The plate is then brought by means of a stream of
heated gas, conveyed through a flue p to a temperature which completely softens
the sheet of glass but does not melt it again, so that the sheet lies completely flat
throughout on the fire-proof stone bottom (previously heated to the same tempera-
ture) which is quite eren, and "levels out" in such a manner that there is not
the slightest unevenness, that is to say, the sheet is now quite flat throughout its
surface.
As soon as a fresh sheet is rolled out and ready to be introduced, the transport-
ing rails are set in motion in the known manner and the furnace bottom with the
glass sheet pushed rather more than one length towards the suitably cool part of
the furnace and there kept until the next following sheet is conveyed to its place
and the first simultaneously carried along a length further and placed in a corre-
spondingly cooler position and so on until the first bottom plate comes on to the
set of rollers of the "bridging over" piece i and is conveyed by this means to the
entrance of the cooling gallery k.
Here the glass sheet is already stiffened and can be removed from the bottom
plate without hesitation and taken direct on to the changing bars or rails of the
gallery and carried along, until completely cooled, to the polishing apparatus.
During this operation the bottom plate is carried back into the furnace body g
on to the set of rollers n of the "bridging over" piece h where it is heated again
to the high original temperature by means of a stream of heated gas introduced
through the flue q and conveyed back to the opening o for the purpose of renewing
the described circuit, from which it is easy to perceive that the number of bottom
plates introduced into the circuit of the annealing furnace or rather surface fur-
nace is the same as that of the melting furnace furnace pots set in action.
The glass sheets now completely cooled and entirely even throughout their sur-
face would, on account of the weakness or in other words the thinness of the glass,
be in danger of being broken in the ordinary polishing process owing to the pres-
sure being too great by reason of the weight of the polishing frame rotating on
them whereas, by the new polishing process, all breakage is avoided, this being
due to the fact that the sheets of mirror glass are not polished on the upper sur-
face by means of the ordinary polishing apparatus but are firmly cemented for
this purpose to the under surfaces of polishing plates r, guided freely in a vertical
direction in a fixed frame and set in rotation around their axes by means of the
polishing tablet rotating below and, in consequence of the combined effect of
these two movements are very rapidly and finely polished.
66
The fixed frame is composed of the four uprights placed around the table and
connected by cross bars on which are eyes" to serving to receive the pins
of the rotating plates and keep them in position, whilst the table & rotated on a
vertical shaft y in a vertical bearing by means of suitable bevel wheels rotates
the plates around their axes. Instead of only a single large sheet of glass,
several small sheets can be polished by means of suitably formed plates.
As a matter of course, also, any other suitable form of construction of the polish-
ing apparatus can he employed, without going beyond the scope of the new
process so long as the principle of relieving the sheets of glass of weight and
consequent undue pressure, by the described means, for the purpose of handling
them without danger of breaking, is preserved.

page_text: Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:
:-
1. Process for producing thin sheets of cast mirror glass of uniform thickness
throughout, the distinguishing feature of which is that the cast glass prepared
in the melting furnace and rolled out into thin plates, upon entering the anneal-
ing furnace is heated and annealed again on a flat moving furnace bottom for the
purpose of being made quite even and being gradually further conveyed and
stiffened is conducted, upon leaving the annealing furnace, from the furnace
bottom and to the polishing apparatus, the furnace plate being brought back
and re-heated to the temperature required for the treatment of the next glass
plate entering the annealing furnace.
2. In the process claimed under Claim 1, a form of the melting furnace, dis-
tinguished by the attaching of two preliminary annealing furnaces to the ends of
the same, for enabling the work to be carried on continuously by means of a
single furnace and a single heating.
3. In connection with the process claimed under Claim 1, the form of the
annealing furnace or surface furnace, distinguished by two parallel furnace bodies
connected together at the top ends and furnished with suitable heating flues and
means of conveying the sheets of glass and the furnace bottoms bearing the same
for keeping a certain number of furnace bottoms in an uninterrupted circuit,
so that a re-heated furnace bottom always enters into the circuit in the place of
the preceding one for the purpose of receiving a sheet of evenly rolled out glass.
4. In the process indicated under Claim 1, the polishing process of the thin
sheets of cast glass, the distinguishing feature of which is that in order that the
sheets of glass may be relieved of weight and consequent undue pressure, they
are firmly cemented to the under surfaces of a set of rotating plates, set in motion
by a polishing table rotating beneath them, and freely guided in a vertical direc-
tion by a fixed frame and in consequence of the combined effect of the peculiar
rotating arrangement and the table are polished.
Dated this 9th day of January 1900.