Improvements relating to the Manufacture of Steel and to Furnaces therefor.
Year: 1892

page_text: Date of Application, 27th Aug., 1892
Complete Specification Left, 26th May, 1893—Accepted, 29th July, 1893
PROVISIONAL SPECIFICATION.
[Communicated from abroad by GEORGE FREDERICK SIMONDS, of Fitchburg,
Massachusetts, United States of America, Engineer.]
Improvements relating to the Manufacture of Steel and to
Furnaces therefor.
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co. Patent Agents,
45 Southampton Buildings, in the County of Middlesex, do hereby declare the nature
of this invention to be as follows:-'
One part of this invention has for its object the manufacture of steel by an
improved case-hardening or cementation process for treating low carbon steel or
wrought iron, whereby an article having the characteristic qualities of refined high
grade steel can be economically produced in a much shorter time and at less expense
than is required by the processes heretofore known and practised.
Another part of the said invention has for it object to produce a furnace designed
to secure a uniformly intense degree of heat in an air-tight heating chamber. Such
a furnace is particularly adapted and is intended for the manufacture of steel
according to the process herein described.
An important feature of my improved process of manufacture consists in
subjecting iron or low steel while in contact with carbonaceous material, to a
temperature below the melting point of cast-iron in a chamber from which all
oxygen is excluded, for the time required to produce the desired quality of
steel.
The walls of my improved furnace are so constructed and the flues are SO
arranged therein as to be impenetrable by heat, so that a uniform high temperature
can be maintained in the heating or converting chamber and a large saving effected
in the consumption of fuel. My improved furnace is moreover practically
air-tight so that all free oxygen is excluded from the heating or converting
chamber.
In carbonizing wrought iron or low steel according to my improved process, the
pieces of iron or the like required to be carbonized are enclosed with carbonaceous
material in refractory boxes or receptacles of suitable shape and size. The closed
boxes or receptacles with their contents are then heated for a suitable time in the
heating chamber from which oxygen is excluded. The said heating chamber is
preferably provided with non-conducting walls so that all the heat is expended in
effecting the carbonization of the metal under treatment thereby lessening the
length of time required for the process.
As soon as the required degree of carbonization is attained the closed boxes or
receptacles containing the metal pieces or articles will be removed from the con-
verting chamber and the steel allowed to gradually cool in said boxes or receptacles
until the temperature is sufficiently reduced to permit handling and exposure of the
articles to the atmosphere without injury.
Steel manufactured or produced by this improved process can be readily hardened,
tempered, or annealed by any approved method and will be found to possess all the
desirable qualities that are characteristic of a product of high grade. While the
quality of the product obtained by this process is such as to suit it to the various
requirements of steel in the arts, it is obvious that the conditions of its manufacture
as above described are such as will result in a large saving in the cost of
production.
If it is desired to carbonize only certain portions of the surface of an article or
piece of metal those portions that are not to be carbonized must be protected by a

page_text: suitable covering that will resist the action of heat and be impenetrable by the
carbon. Coverings of clay have been used for this purpose but are objectionable
because they are not sufficiently adhesive and are liable to shrink or crack and thus
become displaced. I have found that an adhesive paint composed of sizing and a
metallic powder forms an effective and easily applied coating for protecting such
surfaces as do not require carbonizing. I prefer to employ a preparation of sizing
and powdered bronze or sulphate of copper in suitable proportions to form a
mixture that can he readily applied with a brush. A thin coating of this paint
will be sufficient, and it will adhere to the article or surface in such a manner as to
thoroughly protect the same at those points, where carbonization. is not required.
By my process of treating wrought iron or low carbon steel carbonization-can be
carried to a greater depth than is possible by the usual well known method of case-
hardening, the process is accomplished in much less than the usual length of time
and with great economy of fuel and the article will remain unchanged in form and
free from scale.
A suitable furnace for heating articles as above described may be constructed
according to one method of carrying out my invention, as follows.
The walls of the fire chamber and heating converting chamber are made double
with dead air-spaces enclosed therein, I prefer to cover the said walls on the outside
with a layer of cement and asbestos and to build the outermost wall or casing of
the furnace at a suitable distance from the inner walls so as to afford other dead air
spaces. The doors of the ashpit, fire chamber and heating or converting chamber
are made so as to be air tight when closed, they are preferably constructed of metal
with a non-conducting core such as asbestos or carbonate of magnesia, and with a
lining of fire-brick or other refractory substance. The flues which afford commu-
nication between the fire chamber and the heating chamber are so disposed as to
spread the heated gases produced by the fuel, uniformly over the heating chamber.
I prefer to place the exit flues from the heating chamber on opposite sides of the
said chamber so as to aid in securing a uniform heat therein.
I may use a damper of special construction in the main flue leading to the
uptake said damper being provided with an opening of sufficient area to provide
for a suitable draft when the damper is closed.
By means of a furnace constructed substantially as above described I am enabled
to maintain a uniform heat in the heating chamber for any length of time with a
small expenditure of fuel. Moreover free oxygen is entirely excluded from the
heating chamber.
Dated this 27th day August 1802
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements relating to the Manufacture of Steel and to
Furnaces therefor.
1, HENRY HARRIS LAKE, of the Firm of Haseltine Lake & Co., Patent
Agents, 45 Southampton Buildings, in the County of Middlesex, 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 :-
One part of this invention has for its object. the manufacture of steel by an
improved case hardening or cementation process for treating low carbon steel.or
wrought iron, whereby an article having the characteristic qualities of refined high
grade steel can be economically produced in a much shorter time and at less expense.
than is required by the processes heretofore known and practised.
Another part of the said invention has for its object to produce a furnace

page_text: designed to secure a uniformly intense degree of heat in an air-tight heating
chamber. Such a furnace is particularly adapted and is intended for the manu-
facture of steel according to the process herein described.
An important feature of my improved process of manufacture consists in
subjecting iron or low steel while in contact with carbonaceous material, to 'a
temperature below the melting point of cast-iron in a chamber from which all
oxygen is excluded, for the time required to produce the desired quality of steel.
The walls of my improved furnace are so constructed and the flues are so
arranged therein as to be impenetrable by heat so that a uniform high temperature
can be maintained in the heating or converting chamber and a large saving effected
in the consumption of fuel.
My improved furnace is morcover practically-air-tight so that all or nearly all
free oxygen, that is to say oxygen not held in chemical combination, is excluded
from the heating or converting chamber.
In carbonizing wrought iron or low steel according to my improved process, the
pieces of iron or the like required to be carbonized are enclosed with carbonaceous
material in refractory boxes or receptacles of suitable shape and size. The closed
boxes or receptacles with their contents are then heated for a suitable time in the
heating chamber from which oxygen is excluded. The said heating chamber is
preferably provided with non-conducting walls so that all the heat is expended in
effecting the carbonization of the metal under treatment thereby lessening the
length of time required for the process.
As soon as the required degree of carbonization is attained the closed boxes or
receptacles containing the metal pieces or articles will be removed from the con-
verting chamber and the steel allowed to gradually cool in said boxes or receptacles
until the temperature is sufficiently reduced to permit handling and exposure of the
articles to the atmosphere without injury.
In the accompanying drawing,
Figure 1 represents a sectional side elevation of a furnace suitable for use in my
improved manufacture.
Figure 2, is a view of a damper for the furnace flue.
Figure 3 is a view of a piece of metal having portions thereof carbonized
according to my invention.
Referring to Figure 1, the numeral 1 designates the ash pit of the furnace, 2 the
grate 3 the fire chamber; and 4 the heating or converting chamber. The grate
may be of any suitable or well known construction and the ash pit is provided with
air inlets 5, located at any convenient points.
The double main wall 6 of the furnace which extends along both sides and across
the rear, is preferably constructed of brick masonry in such a manner as to enclose
a dead air space 7 having a width of between one and two inches. On the inside of
this double wall 6 is constructed a lining 8 of fire bricks or other refractory
material resting on a support 9 of brick masonry as shown. The outside of the
double wall 6 is completely covered with Kings Windsor cement or other suitable
cement coating 10 and this in turn, is covered with a layer of asbestos 11 to more
thoroughly prevent the passage of heat from the furnace.
If desired the furnace walls may be braced by means of vertically and horizontally
arranged metal plates or bars 12 placed against the outside of the asbestos
covering 11 and securely connected by tie-rods 13 as shown.
At a distance of, say, two or three inches, more or less, from the main double
wall 6 is constructed an outer wall or casing 14, preferably of brick masonry, so
arranged that a dead air space 15 will be left between the main furnace wall and
the said casing.
The top or roof of the furnace is preferably constructed in the same manner as
the side and rear walls with dead air spaces 7 and 15 in which are arranged the
metal T-beams 16, that assist in supporting and strengthening the roof.
By constructing the walls and roof of the furnace with intermediate dead air
spaces and interposed layers of cement and asbestos there will be no loss of heat

page_text: by conduction and the converting or heating chamber 4 can be thus maintained at
a uniform temperature without difficulty and with no great expense for fuel.
The furnace is provided with an ash-pit door 17, a fire chamber door 18 and a
door 19 for giving access to the heating or converting chamber. These doors are
constructed of metal and recessed on their inner sides to receive non-conducting or
fire-proof linings, as shown. For the ash-pit door 17 a lining 20 of carbonate of
magnesia or other suitable non-conducting material will be sufficient. In the
doors 18 and 19 of the fire chamber 3 and converting chamber 4 the lining or
packing 20 of carbonate of magnesia or similar substance may be covered with a
layer of asbestos 21 and to the inner side of each of said doors 18 and 19 is then
attached a lining 22 of fire brick or other suitable refractory material. It will be
seen that each of the doors 17, 18 and 19 is, when closed, tightly fitted within a
metallic casing 23 packed with non-conducting material and forming part of the
furnace front. The upper door 19 that affords access to the converting chamber is
provided with lugs 24 for use in drawing it outward from the door casing when it
can then be raised by means of suitable tackle along vertical guide ways 25,
arranged at the front upper portion of the furnace. When closed, the doors can
be fastened by any suitable means. The non-conducting and air tight construction
of all the furnace doors prevents loss of heat at the front of the furnace by radiation
or conduction and obstructs the access of oxygen to the converting chamber when
the furnace is closed and in operation.
The floor of the converting or heating chamber 4 consists of refractory tiles 26,
preferably having rabbeted joints and supported on refractory brackets 27 sprung
from the upper part of the walls of the fire chamber 3 which is located immediately
beneath the heating or converting chamber and separated therefrom by the said
tiles 26. The tile floor 26 is of such width and length and is so arranged on its
supports 27 as to provide for fines 28 on each side and in front through which the
fire chamber 3 and heating chamber 4 communicate. Leading from opposite sides
of the converting or heating chamber 4 at about half its length more or less, are
exit flues 29 which extend horizontally outward through the fire brick lining 8 and
then slightly downward and in a horizontal direction within the side and rear walls 6
of the furnace. That portion of the exit Hue 29 which is located in the rear
furnace wall discharges into a horizontal flue extension 30 which leads into a
chimney or uptake 31 at the rear of the furnace.
For the purpose of controlling the temperature of the heating of converting
chamber and economizing the heat a vertically movable damper 32 is arranged to
be operated within a frame or casing 33 inserted in the flue extension 30 adjacent
to the furnace chimney. As shown in Figure 2 this damper consists of a
rectangular plate corresponding with the contour of the flue in which it is placed
and is strengthened on one side by annular and radial webs or corrugations 34
surrounding a central opening 35 of sufficient area to provide for a suitable draft
when the damper is closed. The damper is raised and lowered by means of suitable
tackle connected with a lug 36 on its upper edge. It is my purpose to provide the
furnace with interchangeable dampers having openings 35 of varying area to suit
different requirements as to draft. In starting a fire the damper may be opened to
its full extent until the fuel is well ignited and then when again closed the
permanent opening 35 will be sufficient for the requirements of the furnace while
in operation.
In the front wall of the furnace between the enclosed chambers and the furnace
front is a double thickness of fire brick or refractory furnace lining 37 in which
dead air spaces 38 may be formed as shown in Figure 1. Additional dead air
spaces may also be formed in or around the lining that surrounds the fire chamber.
The converting or heating chamber 4 is made to occupy.substantially the central
upper portion of the furnace where it is exposed to a uniform heat and by reason
of the arrangement of the flues 28 and 29 on each side, as shown, the heat is so
evenly distributed throughout the said converting chamber as to produce the most
satisfactory results on the articles or material under treatment.

page_text: By means of a furnace constructed and arranged substantially as above described,
having non-conducting walls impenetrable by heat and a heating or converting
chamber from which oxygen is excluded I am enabled to secure and maintain a
temperature below the melting point of cast-iron, and yet of such uniform degree
and intense quality that the wrought iron or low steel under treatment therein will
absorb or take up the surrounding carbon more readily and quickly than has been
heretofore accomplished.
In practising my improved process of carbonizing wrought iron or low steel I
bring the heating or converting chamber to a temperature below the melting point
of cast-iron, say 1200 to 1500 degrees Fahrenheit, more or less. The best results
are obtained when the furnace is at a yellow or orange colored heat. When the
desired temperature is attained the furnace damper is closed and all air excluded
except the small quantity necessary for maintaining combustion of the fuel in the
fire chamber. The pieces of wrought iron or low steel are embedded in powdered
carbonaceous material, such as charcoal, and inclosed therewith.in covered cast-iron
boxes or receptacles 40 of suitable form and size. These closed boxes or receptacles
with their contents are then placed in the heating or converting chamber from
which oxygen is excluded when the air tight door of said chamber is closed. The
time required for effecting the carbonization of the material treated will vary from
six to forty-eight hours, more or less, according to the dimensions of the articles or
pieces of metal and the extent or depth of carbonization required. Owing to the
exclusion of oxygen, other than that held in chemical combination with carbon and
other substances, from the converting chamber, and the uniform quality or intensity
of heat throughout said chamber from front to rear, and by reason of the
non-conducting walls that inclose the air tight converting chamber, the heat
energy will be almost wholly expended in effecting the carbonization of the metal
under treatment, thereby causing the carbon to be absorbed readily and quickly
with the result of greatly lessening the length of time usually required for
completing the process.
As soon as the required degree of carbonization is attained the closed boxes or
receptacles containing the metal pieces or articles will be removed from the
converting chamber and the steel allowed to gradually cool in said boxes or
receptacles until the temperature is sufficiently reduced to permit handling and
exposure of the articles to the atmosphere without injury.
Steel manufactured or produced by this improved process can be readily
hardened, tempered or annealed by any approved method and will be found to
possess all the desirable qualities that are characteristic of a product of high grade.
While the quality of the product obtained by this process is such as to suit it to the
various requirements of steel in the arts it is obvious that the conditions of its
manufacture as above described are such as will result in a large saving in the cost
of production.
If it is desired to carbonize only certain portions of the surface of an article or
piece of metal those portions that are not to be carbonized must be protected by a
suitable covering that will resist the action of heat and be impenetrable by the
carbon. Coverings of clay have been used for this purpose but are objectionable
because they are not sufficiently adhesive and are liable to shrink or crack and thus
become displaced. I have found that an adhesive paint composed of sizing and a
metallic powder forms an effective and easily applied coating for protecting such
surfaces as do not require carbonizing. I prefer to employ a preparation of sizing
and powdered bronze or sulphate of copper in suitable proportions to form a
mixture that can be readily applied with a brush. A thin coating of this paint
will be sufficient, and it will adhere to the article or surface in such a manner as to
thoroughly protect the same at those points where carbonization is not required.
In Figure 3 the numeral 41 designates the core or tough central portion of a piece
of wrought iron or low steel, 42 the portions that have been carbonized and 43 the
protection coating or covering of adhesive paint applied to those contiguous
surfaces where carbonization was not required.

page_text: By my process of treating wrought iron or low carbon steel carbonization can be
carried to a greater depth than is possible by the usual well known method of case
hardening the process is accomplished in much less than the usual length of time
and with greater economy of fuel; and the article will remain unchanged in form
and free from scale.
Having now particularly described and ascertained the nature of this 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. In a process for carbonizing wrought iron or low-carbon steel, subjecting the
metal while surrounded with carbonaceous material to the required degree of
heat in a heating chamber from which all or nearly all oxygen not held in chemical
combination is excluded, substantially as, and for the purpose; specified.
2. The method of protecting a surface of wrought iron or low-carbon steel from
the penetration of carbonaceous material in a carbonizing process, by coating the
said surface with an adhesive paint composed of sizing and a metallic powder,
substantially as described.
3. The improved method of carbonizing wrought iron or low steel conducted
substantially as described for the purpose specified.
4. A furnace for use in the manufacture of steel having a heating chamber
from which all or nearly all oxygen not held in chemical combination is excluded
when the furnace is in use, substantially as described, for the purpose specified.
5. A metallurgical furnace having non-conducting walls provided with inter-
mediate dead air spaces and interposed layers or coverings of cement and asbestos,
substantially as described, for the purpose specified.
6. The improved furnace constructed substantially as described with reference to
Figure 1 of the accompanying drawings, for the purpose specified.
Dated this 26th day of May 1893.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.