IMPROVEMENTS IN APPARATUS FOR THE MANUFACTURE OF MALLEABLE CAST IRON
Year: 1871

page_text: LETTERS PATENT to Frederick Arthur Paget, of 1, Seymour Chambers,
•
Adelphi, W.C., in the County of Middlesex, Engineer, for the Inven-
tion of "IMPROVEMENTS IN APPARATUS FOR THE MANUFACTURE OF MALLEABLE
CAST IRON."
Sealed the 27th June 1871, and dated the 25th February 1871.
PROVISIONAL SPECIFICATION left by the said Frederick Arthur Paget
at the Office of the Commissioners of Patents, with his Petition,
on the 25th February 1871.
I, FREDERICK ARTHUR PAGET, of 1, Seymour Chambers, Adelphi,
W.C., in the County of Middlesex, Engineer, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN APPARATUS FOR THE
MANUFACTURE OF MALLEABLE CAST IRON," to be as follows:-
The first part of this Invention relates to improvements in the
annealing ovens used in the manufacture of malleable cast iron, by
which they are made continuous, or almost continuous, in their action.

page_text: The second part relates to the so-called annealing pans, pots, or
crucibles, or also compartments or cases used in the said manufacture,
and generally formed of cast iron, whereby their outer surfaces aro
rendered less liable to be scaled or oxidised by the fire gases.
I prefer to construct the furnace externally somewhat in the form
most generally used, that is to say, two long grates are employed
extending each side of nearly the whole length of the annealing oven.
In so-called pan ovens or furnaces the fire gases from these grates rise
up between tiers or vertical columns of so-called pans packed with the
castings to be annealed. The fire gases after passing between the
annealing pans placed in rows along the centre of the furnace, which
central portion is generally somewhat raised above the level of the fire-
bars, make their way either into a flue in the arch of the furnace, or
into another flue opening from below, either in the wall or the raised
bottom or sole of the oven. The flues are provided with suitable
dampers, so that they may be alternately closed and opened. When
articles have been packed into the pans, which is donc inside the
ordinary oven, the man-hole is bricked up, the fires raised and con-
tinued till the castings have been sufficiently annealed. The heat is
then allowed to fall, and when the oven has cooled down its contents
are removed.
This process evidently involves both loss of heat and of the time
spent while the furnace is cooling down. Usually one furnace can only
be used about half time. It also involves loss of fuel, from the im-
possibility of so clothing the furnace as to prevent the transinission
of heat, additional expence in labour from the necessity of packing the
castings inside the oven, and much inconvenience and delay from the
impossibility of getting access to the oven till the close of the operation,
thus delaying the annealing of any casting that may be wanted in
a hurry.
Now I obviate all these objections in the following modes:-At the
inner and opposite side of each of the grates and parallel with them I
construct a fire-bridge, by preference of cast iron faced with fire-clay, on
its side nearest the fire-bars. The inner intermediate space between the
two fire-bridges I leave open and keep level with the ground. On this
I place a line of rails in order to receive the wheels cast with tyres of
a truck or trucks. Though one such truck may be used, I prefer in a
furnace of ordinary size to use two or more. The tops of these trucks

page_text: are lined with fire-bricks, and the floor thus formed by them reacles a
few inches below the tops of the two fire-bridges. I prefer to cast the
sides of the trucks tapering downwards from their outside edges. In
order to somewhat cool the bottom of the truck or trucks I may
introduce a narrow covered channel or canal along the whole length of
the bottom of the oven, open at both ends outside, so that a current of
air may play through it. The door is by preference bolted to one end
of one of these trucks, and its sides taper inside, so as to form a joint
with the front wall of the oven; or the door may be made separate, and
to slide at right angles to and in front of the furnace on rollers, fixed
either to the door itself or to the oven front. The main door can also be
made with an independent smaller door. The pair of rails inside the
oven are connected to a small turntable in front of and outside the oven,
and thence with another line of rails running cither parallel with the
oven or ovens, or otherwise, as most convenient. The small space left
open between the rails, if not quite covered by the door, can be bricked
up or luted with clay or sand. Clay or sand may also be laid all round
the edges of the trucks, so as to form a joint, though this is not.
necessary. While a charge is being annealed in this oven another is
being packed outside on a fresh relay of trucks, which can then be at
once run into the oven after the first has been discharged. When that
form of door is used which is secured to one of the trucks, it is found
most convenient to employ two such doors, cach bolted or otherwise
secured to its own truck. Through or in the arch of the oven or furnace
I prefer to make or fix tubes for firing from above with small coal, or
with the breeze obtained by screening and washing the droppings from
between the fire-bars. This is upon the well-known plan first invented
by Friedrich Hoffmann, of Berlin, and extensively applied by him to
his continuous brick and other kilns. In my annealing oven it would
only be applied intermittently, or when the fire-brick tops of the
carriages get sufficiently heated to inflame such small fuel. In order
to obtain access to these fire holes in the roof of the furnace steps may
be made up to the top, by preference between each pair of ovens when
two are erected.
Several variations in detail may be made. Thus, the oven can either
be fired from the same end as that at which the trucks or carriages are
run in, or it may be fired at the opposite end. Firing holes from the

page_text: dispensed with; or so-called step or inclined grates for small fuel fired
from both ends of the furnace or otherwise may be used. The fire gases
instead of being led up at once amongst the annealing pans or casings
as described, may be led in amongst the tiers of pans through slits or
loop holes in walls formed by raising the fire-bridges up to the arch of
the oven. Instead of two flues, as described, only one flue, preferably
opening in the arch of the oven, may be used. A separate truck may be
employed for the door, instead of its being fixed to one of the trucks for
taking the annealing pans, or the door may be made to slide in front of
the oven, as above described, or it may be set on hinges to the ovens.
The relative arrangements of the ovens and turntables may also be
varied, or no turntable may be used, and the carriages may be run
direct into the furnace; or a turntable placed between the fronts of two
or more opposite furnaces may be made to serve for both. With regard
to the means for keeping in the heat, the complete adoption of which is :
rendered passible from there being no necessity for allowing the furnace
to cool down, the furnace can either be simply built with unusually
thick walls, or be made with a casing of sand enclosed between a thin
brick wall and the furnace walls themselves.
My improvements in the cast-iron annealing pans, pots, crucibles,
and cases or casings used in the manufacture of malleable cast iron for
containing the castings while being annealed relate to a process for
preventing or delaying the very rapid oxidation or scaling of their outer
surfaces that takes place while they are being submitted to the fire
gases of the furnace, and by which much loss is caused.
The leading feature of the plan upon which I proceed is to cast such
pans with outer surfaces so roughened or indented, or so made with
alternate concavities and convexities as to favour the adhesion of a
coating or coatings of fire-clay, clay, lime, or other non-oxidizable
composition or compositions, so as to afford a non-oxidizable surface to;
the direct action of the flame. I may thus cast the outer surfaces of
such pans, with square, lozenge, circular, or hexagonal cells, or with
knobs or points, or with vertical or horizontal ribs or flutings. I prefer,
however, to cast shallow vertical dovetails at short intervals on the
peripheries of the pans, as the dovetail form allows for the contraction
of the clay on being heated, preventing its falling out, while it gives
the clay a hold, though the pans themselves expand under the heat.
may have cross dovetails joining these vertical grooves, or dovetails or
I

page_text: horizontal dovetails alone; but I prefer to use vertical dovetails alone,
as I am thus enabled to employ a pattern for a mould not requiring any
cores, and which may be at once taken out of the sand. A coating of
fire-clay is by preference painted on each annealing pan before being
charged into the furnace. The parts of the cast-iron cases when used
in such furnaces instead of pans are prepared in a manner similar to
that just described.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Frederick Arthur Paget in the Great Seal Patent
Office on the 25th August 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FREDERICK
ARTHUR PAGET, of 1, Seymour Chambers, in the County of Middlesex,
Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fifth day of February, in the
year of our Lord One thousand eight hundred and seventy-one, in the
thirty-fourth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Frederick Arthur Paget, Her special
licence that I, the said Frederick Arthur Paget, my executors, admi-
nistrators, and assigns, or such others as I, the said Frederick Arthur
Paget, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN APPARATUS FOR THE MANUFACTURE OF MALLEABLE CAST
IRON," upon the condition (amongst others) that I, the said Frederick
Arthur Paget, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, should
particularly describe and ascertain the nature of the said Invention,
and in what manuer the same was to be performed, and cause the
same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Frederick Arthur Paget, do hereby
declare the nature of the said Invention, and in what manner the same

page_text: is to be performed, to be particularly described and ascertained in and
by the following statement :-
I prefer to construct the furnace externally somewhat in the form
most generally used, that is to say, two long grates are employed
extending each side of nearly the whole length of the annealing oven.
In so-called pan ovens or furnaces the fire gases from these grates
rise up between tiers or vertical columns of so-called annealing pans
packed with the castings to be annealed. The fire gases after passing
between the annealing pans placed in rows along the centre of the
furnace, which central portion is generally somewhat raised above the
level of the fire-bars, make their way either into a flue in the arch of
the furnace or into another flue opening from below, either in the wall
or the raised bottom or sole of the oven. The flues are provided with
suitable dampers, so that they may be alternately closed and opened.
When the articles have been packed into the pans, which is done inside
the ordinary oven, the man-hole is bricked up, the fires raised, and
continued till the castings have been sufficiently annealed. The heat is
then allowed to fall and when the oven has cooled down its contents
are removed.
This process evidently involves both loss of heat and of the time
spent while the furnace is cooling down. Usually one furnace can
only be used about half time. It also involves loss of fuel from the
impossibility of so clothing the furnace as to prevent the transmission
of beat, additional expense in labour from the necessity of packing
the castings inside the oven, and much inconvenience and delay from
the impossibility of getting access to the oven till the close of the
operation, thus delaying the annealing of any casting that may be
wanted in a hurry.
Now I obviate all these objections in the following modes:-At the
inner and opposite sides of each of the grates and parallel with them I
construct a fire-bridge by preference of cast iron faced with fire-clay on
its side nearest the fire-bars. The inner intermediate space between the
two fire-bridges 1 leave open and keep level with the ground. On this I
place a line of rails in order to receive the wheels cast with tyres of a
truck or trucks. Though one such truck may be used I prefer in a
furnace of ordinary size to use two or more. The tops of these trucks
are lined with fire-brick, and the floor thus formed by them reaches a
few inches below the tops of the two fire-bridges. I prefer to cast the

page_text: sides of the trucks tapering from their outside edges. In order to
somewhat cool the bottoms of the truck or trucks I may introduce a
narrow covered channel or canal along the whole length of the furnace
open at both ends outside, so that a current of air may play through it.
The door is by preference bolted to one end of one of these trucks, and
its sides taper inside so as to form a joint with the front wall of the
oven; or the door may be made separate and to slide at right angles
to and in and in front of the furnace on rollers fixed either to the door
itself or to the oven front. The main door can also be made with an
independent smaller door. The pair of rails inside the oven are con-
nected to a small turntable in front of and outside the oven, and thence
with another line of rails running either parallel with the oven or ovens,
or otherwise, as most convenient. The small space left open between
the rails, if not quite covered by the door, can be bricked up or luted
with clay or sand. Clay or sand may also be laid all round the edges
of the trucks so as to form a joint, though this is not necessary. While
a charge is being annealed in the oven another is being packed outside
on a fresh relay of trucks, which can then be at once run into the oven
after the first has been discharged. When the form of door is used
which is secured to one of the trucks it is found most convenient to
employ two such doors, each bolted or otherwise secured to its own
truck. Through or in the arch of the oven or furnace I prefer to make
or fix tubes for firing from above with small coal or with the breeze
obtained by screening and washing the droppings from between the
fire-bars. This is upon the well-known plan first invented by Friedrich
Hoffmann, of Berlin, and extensively applied by him to his continuous
brick and other kilns. In my annealing oven it would only be applied
intermittently or when the fire-brick tops of the carriages got sufficiently
heated to inflame such small fuel. In order to obtain access to these
fire holes in the roof of the furnace steps may be made up to the top,
by preference between each pair of ovens when two are crected.
Several variations in detail may be made. Thus, the oven can either
be fired from the same end as that at which the trucks or carriages are
run in, or it may be fired at the opposite end. Firing holes from the
top on the Hoffmann plan, as described above, may also be entirely
dispensed with. Or so-called step or inclined grates for small fuel
fired from both ends of the furnace or otherwise may be used. The
fire-grates instead of being led up at once amongst the annealing pans

page_text: or casings, as described, may be led in amongst the tiers of pans
through slits or loop holes in walls formed by raising the fire-bridges
up to the arch of the oven. Instead of two flues, as described, only
one flue, preferably opening in the arch of the oven, may be used. A
separate truck may be employed for the door instead of its being fixed
to one of the trucks for taking the annealing pans, or the door may
be made to slide in front of the oven, as above described, or it may
he set on hinges to the oven. The relative arrangements of the ovens
and turntables may also be varied, or no turntable may be used and the
.carriages may be run direct into the furnace; or a turntable placed
between the fronts of two or more opposite furnaces may be made to
serve for both. With regard to the means for keeping in the heat the
complete adoption of which is rendered possible from there being no
necessity for allowing the furnace to cool down the furnace can either be
simply built with unusually thick walls or be made with a casing of sand
enclosed between a thin brick wall and the furnace walls themselves.
My improvements in the cast-iron annealing pans, pots, crucibles,
and cases or casings used in the manufacture of malleable cast iron for
coutaining the castings while being annealed, relate to a process for
preventing or delaying the very rapid oxidation or scaling of their outer
surfaces that takes place while they are being submitted to the fire-
gases of the furnace and by which much loss is caused.
The leading feature of the plan upon which I proceed is to cast such
pans with outer surfaces so roughened or indented, or so made with
alternate concavities and convexities, as to favour the adhesion of a
coating or coatings of fire-clay, clay, lime, or other non-oxidizable com-
position or compositions, so as to afford a non-oxidizable surface to the
direct action of the flame. I may thus cast the outer surfaces of such
pans with square, lozenge, circular or hexagonal cells, or with knobs or
points, or with vertical or horizontal ribs or flutings. I prefer, however,
to cast shallow vertical dovetails at short intervals on the peripheries
of the pans as the dovetail form allows for the contraction of the clay
on being heated, preventing its falling out, while it gives the clay a hold,
though the pans themselves expand under the heat. I may have cross
dovetails joining these vertical grooves or dovetails or horizontal dove-
tails alone, but I prefer to use vertical dovetails alone, as I am thus
enabled to employ a pattern for a mould not requiring any cores, and
which may be at once taken out of the sand. A coating of fire-clay is

page_text: by preference painted on each annealing pan before being charged into
the furnace. The parts of the cast-iron cases when used in such
furnaces instead of pans are prepared in a manuer similar to that just
described.
Having now stated the object and nature of my Invention I will
proceed to describe it more particularly by the aid of the accompanying
Drawings.
Figure 1 is a cross section of one of my ovens for annealing malleable
cast iron, in which the stoking doors are at the end opposite to that at
which the trucks are run in; Fig. 2 is a front elevation of an oven in
which all the doors are at the same end; Fig. 3 is a sectional plan of
Fig. 1, while Fig. 4 is a sectional plan of Fig. 2; Fig. 5 is a longitudinal
cross section of the oven shewn in Figures 2 and 4; while Fig. 6 is a
portion of the same section of Figures 1 and 3; Figures 7 and 8 re-
spectively indicate an elevation and plan of the improved form of
annealing pan. The same letters refer to all the Figures.
A1, A2, are the movable trucks, on one of which is bolted the door B
of cast iron lined with fire-brick. It is cast with a flange all round and
the joint with the wall of the furnace is preferably formed of wetted
fire-clay which is smeared on before the truck is run in; G is the turn-
table in front; D1, D2, indicate the long fire-bridges; E, E, E, E, are
the firing holes at top for feeding in small fuel when the oven has
reached a sufficiently incandescent state; F, F, F, F, are the stoking
doors for firing in the usual way; G is the outer covering of the oven;
His a canal which may or may not be adopted to keep the bottom
parts of the trucks cool. The two flues for the fire gases are of the
character usual in these ovens; the top one is dotted on the plan on
Fig. 4 and its connection shewn with the chimney, and the bottom flue
is indicated on Fig. 1, 3, and 5; P, P, P, are the pans, the form of
which is more particularly shewn on the enlarged Figures 7 and 8.
These pans may, of course, be cast in other shapes, such as square or
other sections appropriate to the articles to be annealed.
I am aware that the plan of constructing annealing furnaces and
ovens with movable trucks is not new, as it is applied by Mr. Krupp,
at Essen, for heavy steel forgings; by Mr. C. W. Siemens, for annealing
glass; at sundry works in Birmingham for anncaling copper and wire.
A form is shewn in Specification No. 2022, A.D. 1863, for annealing

page_text: glass in No. 1038, A.D. 1868, for pottery and brick kilns; and
No. 778, A.D. 1857, shews a rotating table.
I therefore only claim the constructions of ovens above described, as
applied to the manufacture of malleable cast iron.
In witness whereof, I, the said Frederick Arthur Paget, have
hereunto set my hand and seal, this Twenty-fourth day of
August, in the year of our Lord Oue thousand eight hundred
and seventy-one.