Improvements in the Method of and Apparatus for Manufacturing Plate Glass.
Year: 1891

page_text: Date of Application, 24th Nov., 1891-Accepted, 24th Dec., 1891
COMPLETE SPECIFICATION.
Improvements in the Method of and Apparatus for Manufacturing
Plate Glass.
A communication by ROGER SHERMAN PEASE, of Minneapolis, in the County of
Hennepin and State of Minnesota, United States of America.
1, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for
Foreign Patent Solicitors, 6, Lord Street, Liverpool and 6, Bank Street
Manchester, both in the County of Lancaster, and 323 High Holborn in the
County of Middlesex, Civil Engineer, 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 relates to the manufacture of plate glass, and consists primarily
in pouring the metal directly upon the moulding table or bed from pots, within the
furnace or melting oven, so as to avoid the necessity of either first drawing off the
metal from a tank or of removing the pots from the oven and subjecting them to
changes of temperature.
In the annexed drawings-
Figure 1 is a longitudinal sectional view of a pot furnace arranged for carrying
out the invention, the moulding bed being represented as standing beneath the pot
chamber ready to receive the molten metal.
Figure 2 a transverse sectional view showing one of the pots in the act of being
emptied.
Figure 3 a perspective view showing the end of the furnace or moulding table
and the car or table which conveys the glass from the moulding table to the
annealing oven.
Figure 4 a view illustrating the preferred form of the pot.
Figure 5 a sectional view showing the preferred construction and arrangement.of
closure for the opening through which metal is poured, and indicating the relation
of the pot thereto.
Many attempts have been made hitherto to simplify and cheapen the manufacture
of plate glass, and particularly to render the melting process continuous.
With this object in view some have proposed the use of tanks-adapted to contain
a large quantity of molten metal, and to maintain the same in proper working
condition, the design being to draw from the tank the quantity required for.the
formation of one sheet after another, and to supply materials to the tank or to the
melting chamber in proportion to the withdrawal of molten metal therefrom.
In some cases it has been proposed to tap the tank through its bottom-or,in line
with its bottom through one side; but experience has proved that this plan.is.open
to a very serious objection, which is that wherever molten glass-flows through,an
opening in the bottom or wall of a tank, the opening becomes rapidly enlarged,
the fireclay fusing with or being eaten by the molten glass, and the opening being
very rapidly enlarged, so that it is difficult to properly close: it or to regulate the
flow of glass through it.
Others, recognising the above difficulty, have proposed to tip the entire tank, or
to lower one side thereof, so that the molten metal may flow over its edge,,but
provision has usually been made for delivering the metal into portable pots whence
it was to be poured upon the moulding table.
Mr. Pease proposes to avoid the difficulties attending these several ‚plans,—
enlargement of the tap.or opening on the one hand, or the expensive construction
involved in.a tipping tank on the other, by making use of pots and so arranging
them that their contents may be discharged directly on to the, moulding or casting
table without removing the pots from the furnace; and he, has found by practical

page_text: tests that this plan is admirably adapted to the manufacture of plate glass, and
effectually overcomes the difficulties encountered by prior plans.
Referring now to the drawings-
A, indicates a melting oven or chamber containing a series of pots B, which may
be of any suitable capacity, and which are advisably arranged in two rows or
groups, one row at either side of the furnace or oven close to the outer walls
thereof.
Thus arranged, the pots may be readily charged and tipped to discharge their
contents through openings C formed in the side walls of the furnace or oven, and
normally closed by suitable caps or stoppers D, such as are used to close the
working holes of pot furnaces.
E indicates an opening through the floor or bottom of the oven or chamber B,
which opening extends parallel with the side or end walls of the oven, and is
located midway between said walls, the pots B being arranged to face said
openings so that when tipped, their contents shall flow through the same without
coming in contact with the walls or edges thereof.
The opening E may be closed by bricks or blocks F of fire clay laid over the
same; and manipulated by means of a suitable rod in the hands of the workman,
or, as is preferred, the opening may be of the form indicated in Figure 5, and
closing doors or gates G employed to close the opening E.
The bottom or floor of the chamber A is made of fire clay or fire brick, and
inclines downward toward the opening E, as shown in Figures 2 and 5, this for the
double purpose of causing any drip or waste that may occur to flow to the
opening E and also to afford free space for the tipping of the pots to any extent
desired.
As indicated in Figures 1, 2, and 5, the floor of the chamber or oven A is
provided with a backing or support a, of iron or other suitable metal, and in the
preferred form represented in Figure 5 the floor drops or inclines downward toward
the opening E, both inside and outside.
Hinged to the backing a at suitable points are the doors or gates G which are
counterweighted so as to close automatically and to remain closed except when
forcibly drawn open by the attendants, the meeting line of the two doors being so
formed that the gates may swing down one after another without locking or
binding.
A convenient form is represented in Figure 5 where the meeting line is oblique
to a vertical plane, but obviously the meeting line may be a curved instead of a
straight line or plane.
The counterweights C'may be caused to act with any desired force so that if
desired the gates shall remain closed, even though the contents of one or more of
the pots be discharged thereon through the breaking of a pot or otherwise.
To open the gates G, chains or cables H are preferably provided which pass
about pulleys and thence to the front of the furnace or other convenient point
where they may be provided with hand-holes or attached to levers by which
to pull upon them and draw upward the counterweights G', whereby the gates may
be opened.
As indicated in Figure 5, the gates G are formed with metal backings and
faced with fire clay so as to withstand the high heat within the oven or
chamber A.
A single gate may be substituted for the double gates shown, but the double
gates are preferred because of the greater compactness or the smaller amount of
vertical space required it being desirable that the moulding or casting table I be
brought as near to the bottom of the chamber A as practicable.
In practice it will be found desirable to employ as many gates (double or single)
as there are pairs of pots, so that only that portion of the opening E which is
directly in front of the pot or pots to be poured need be opened at any one time.
Without such provision there would be a serious waste of heat and an undue
cooling of the pots and the metal therein.

page_text: In order to bring the moulding or casting table I as near to the bottom of the
chamber as is practicable, the Hoor of said chamber is mounted upon iron beams or
girders, which are in turn carried upon columns or piers so as to leave a free space
below the chamber for the moulding or casting table and permit access to said space
when required.
The moulding or casting table is essentially the same as heretofore used, and
is mounted upon tracks or wheels and arranged to run into and out of the space
beneath the chamber upon suitable rails, as indicated in Figures 1, 2 and 3.
Jindicates the roller by which the glass is rolled out and caused to assume the
proper thickness upon the bed or table, which latter is furnished as usual with side
guards or ways upon which the ends of the roller travel, and by which the
thickness of the sheet is determined.
At the forward or outer end of the table are raised ribs or ways e, which serve
to elevate the roller when its work is completed, and afford space between it and
the table for the passage of the sheet from the table to the annealing oven, or to a
transfer car K, by which the sheet is carried to the annealing oven.
Mounted in suitable standards or bearings at the forward or outer end of the
moulding or casting table I, is a transverse shaft L provided with cranks or
winches by which to rotate it, and with sprocket wheels d, as best shown in
Figures 1 and 3.
At the rear end of the table is a similar shaft M provided with wheels e, which
may be either grooved pulleys or sprocket wheels.
Passing about the pulleys de at each side of the table are chains N which have
attached to them the boxes or bearings of the roller J, so that as the shaft Lis
turned in one or the other directions, the roller J will be caused to traverse the
table in one or the other direction as desired.
O indicates a guard resting upon the bed or table I, and having a perforated lug
or ear through which passes the journal of the roller J, so that the guard is carried
with the roller in its movements forward and backward, there being a similar guard
at each end of the roller to prevent the molten glass from flowing over the sides of
the table as the roller advances.
The arrangement of the roller chains and shafts above set forth is peculiarly
advantageous in connection with this method of operation, for the reason that the
backward as well as the forward movement of the roller may be caused without
drawing the moulding table out from beneath the chamber or oven A, whereas
prior constructions would necessitate the drawing out of the moulding or casting
table, or the use of some other means in addition to the ordinary chains by which
the roller is drawn forward to recede the same.
While the chamber has been described as having a central opening with a series
of pots on either side thereof, it must be distinctly understood that Mr. Pease does
not restrict himself to this arrangement, as he may obviously use a single row of
pots or he may arrange the pots in other ways, for instance in a semicircular group,
in a single straight line along one side of the opening, or otherwise, though the
arrangement illustrated is preferred for the reason that it affords convenient access
to each of the pots and enables the charging and tipping of the same to be
accomplished with ease and facility.
So too, he has represented the passages for the inlet of air and gas from a
regenerator, such as is employed in the well known Siemens type of furnace, but
he does not restrict himself to this or any other specific form of heating apparatus.
Under ordinary circumstances he prefers the type of heater indicated, because
of the intense heat obtainable therefrom, the cleanliness and freedom from smoke
and sulphur, and the economy of fuel.
The pots which he proposes to employ, although ordinary pots may be used, are
of the form shown in Figures 2, 4 and 5, that is to say, the front side of the pot or
vessel is rounded or cut away to such an extent that a very slight pressure forward
will cause the pot to tip and discharge its contents, and so too that the movements

page_text: of the pot may be easily controlled throughout, the rounded rocking or bearing
faces permitting the easy control and tipping of the pot to any desired extent.
Sufficient flat surface or bearing b is left for the pot to stand upon normally.
It is feasible to cut away the front of the pot to such an extent that it shall be
unable to stand alone upon a plane surface, and to block it up or otherwise hold it
against tipping until occasion arises therefor.
In actual practice there is always present upon the floor of the furnace or
melting chamber, more or less molten glass or metal due to spilling in handling,
etcetera, and this, being a viscous substance will serve to retain in upright
position a pot which would otherwise be incapable of standing without props or
locking devices.
For this reason Mr. Pease does not wish to restrict himself to any precise curve,
nor to an exact tipping point, though he prefers a sufficient bottom bearing to
enable the pot to stand alone.
This peculiar formation of the pots is important to the practical carrying out of
the improved method because of the necessity of tipping the pots within the
heating or inelting chamber, and further because it is essential that the contents be
discharged in a mass and not allowed to drip or trickle from the pot because such
slow discharge causes the molten metal to fold upon itself and to enclose bodies of
air which form bubbles in the sheet rolled therefrom.
By retaining the pots within the chamber or oven A at all times, and pouring
the metal therefrom while within said chamber, the changes of temperature are
avoided both in the pot and' in the molten metal which are incident to the delivery
of the molten metal from a tank, into an exposed pot or ladle or to the removal of
a pot from an oven or furnace to the atmosphere, and the life of the pots is con-
sequently greatly prolonged, at the same time ensuring a more uniform quality of
glass,, and rendering, far more easy and certain the casting operation.
The pots may contain different coloured metal so as to produce sheets of
different colours or combinations of colours. The pots may be covered or open, as
preferred.
By some glass workers, or under some circumstances, it is deemed advantageous
to roll the sheet in both directions, one or more times, hence the invention is not to
be understood as restricted to the arrangement of the guards O above described,
but, in some cases, the common plan of connecting the guards by a cross bar
or plate and mounting them loosely upon the table in advance of the roller J, may
be adopted..
It is, and long has been, common to construct a pot chamber with an inclined
bottom leading to a small outlet for the escape of molten glass spilled from a pot or
escaping from a broken pot, and no claim is made to this idea.
In order to secure the practical benefits of the plan; it is necessary that the pots
be arranged in such relation to the opening, and that the opening be of such. size
as to permit the molten glass to be poured directly upon the moulding bed or table,
that is, without coming into contact with the walls of the opening.
It is particularly to be noted that under this arrangement of apparatus and
method of working, the vessel containing the molten metal remains always within
the melting chamber or oven, and is consequently heated evenly in every part,
hences when the pot is tipped to pour the metal, said metal flows over a mouth or
edge and through a space heated to the same temperature as the body of the pot
and the metal itself, touching nothing whatever that might chill it until delivered
upon the moulding or casting. table.
When tapped or siphoned from a tank, the metal is chilled by contact with the
external, exposed, and comparatively cool lip in front of the outlet, and falls to the
mould through the outer air, that is, through air outside of the furnace or heating
chamber..
So far as the communicator is aware, no one has ever before proposed to manu-
facture glass by pouring the molten metal from a pot contained in the. melting

page_text: chamber or oven, and without removing the pot therefrom. By this plan he is
enabled to vastly prolong the life of the pots, avoid chilling or cooling of the
metal, and ensure the formation of perfect plates at greatly reduced cost as
compared with prior plans.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that what I claim is-
1. The herein described method of moulding or casting glass plates or sheets,
which consists in first reducing the charge or metal to a molten state in a pot
or crucible within a melting chamber or oven, second, tipping the pot or crucible
and pouring the molten metal therefrom directly to or upon the moulding bed
or table without removing the pot or crucible from the chamber or exposing it
to the outer air, and third, rolling or spreading the mass into a sheet of proper
thickness.
2. The herein described method of producing glass plates or sheets, which
consists of the following steps, first, reducing the hatch or charge to a molten
state in a pot or crucible within a melting chamber or oven, second, tipping
the pot or crucible and pouring the molten metal directly therefrom to or upon
the moulding bed or table without removing the pot from the chamber, third,
rolling or spreading the mass into a sheet; and, fourth, annealing the sheet.
3. In an apparatus for the manufacture of glass plates or sheets, the combination
of a heating oven or chamber provided with an opening through which molten
metal can be discharged without coming into contact with the floor of the chamber
or the walls of the opening a pot or pots within said chamber adapted to contain
molten metal, and moulding or casting bed located in such relation to the opening
in the furnace and to the pot or pots therein as to directly receive the molten
contents of the latter when poured, substantially as et forth.
4. In combination with chamber A provided with opening E, a pot or pots B
arranged in such relation to the opening that the contents can be poured directly
through said opening, and a casting or moulding table I, located below the
opening E, substantially as shown and described.
5. In combination with chamber or oven A, provided with an opening E in its
floor or bottom, gates or doors G adapted to close said opening, and a pot or pots
located within said chamber and adapted to deliver molten metal directly through
said opening, substantially as described.
6. In combination with chamber or oven A provided with opening E in its floor
or bottom, gates G applied to said opening, counterweights G adapted to hold
the gates closed, and a pot or pots located within chamber A and in such relation
to the opening as to deliver molten metal directly through the opening E when
tipped.
7. In combination with chamber or oven A, provided with opening E, and with
melting pots or crucibles B, counter-weighted gates G, and chains or bands H for
opening the gates, substantially as described.
8. In combination with chamber or oven A provided with opening E, and pot or
pots having a front face rounded or cut away substantially as shown, whereby the
pot is adapted to be rocked or tipped forward and held in any desired position with
the exercise of slight power.
9. In combination with a moulding or casting table 1, roller J, chains or bands N,
shaft L, wheels or pulleys de, about which said bands pass, all constructed and
arranged substantially as set forth, whereby the roller is adapted to be moved
forward and backward over the table without drawing said table from beneath the
furnace or oven in connection with which it is used.
10. The herein described pot or vessel, consisting of a body A of refractory
material, having its front face cut away toward the bottom, substantially as set
forth, whereby it is adapted to be readily tipped, and to be held at any desired
inclination.

page_text: 11. The herein described pot formed with a flat bottom and flat front side, and
having its front face rounded or cut away toward the bottom, substantially as
shown, whereby the pot is adapted to be readily tipped and held in any desired
position.
Dated this 23rd day of November 1891.
WM. P. THOMPSON & Co.,
Agents for the Applicant.