IMPROVEMENTS IN MAKING CORRUGATED BOILER FURNACE SHELLS OF CAST STEEL
Year: 1884

page_text: I, JAMES GRAY LAWRIE, of 2 Westbourne Terrace, Glasgow, in the County of
Lanark, North Britain, Shipbuilder, do hereby declare the nature of my said
invention for "IMPROVEMENTS IN MAKING CORRUGATED BOILER FURNACE SHELLS
OF CAST STEEL to be as follows, that is to say :-
"
My said Invention has for its object the economical manufacture of weldless
corrugated furnace shells for steam boilers; and it consists in forming the shells by
casting then in an improved manner of a suitable quality of steel, and, when
desired, in further treating the castings as hereinafter described.
For the purposes in view it is desirable that the steel shall be in a uniform
condition throughout and shall completely fill the entire mould in which it is
cast; and whilst these conditions are easily secured in cases in which the steel is
of considerable thickness or mass, there is a great liability in the case of com-
paratively thin castings for the steel to become partly solidified before all parts of
the mould are filled, and for the castings to be imperfect. By my Invention this
difficulty is overcome by heating the moulds and keeping them heated whilst the
molten steel is being poured into them.
The moulds may be formed of suitable sand or other similar material in any
suitable known kind of mould boxes; or they may be formed completely or partly
of firebrick or other solid refractory material, the parts of the moulds being held
together by casings or hoops; or the moulds may be formed completely or partly
of cast steel or cast iron the mould surfaces being prepared with a suitable
'blackening" or protective coating. When a mould has been prepared it is
placed in a furnace or oven in which it is heated up to the melting point or to a
temperature as near the melting point of the steel as can be used without injuring
the mould or its frame or binding hoops; and when the interior of the mould is of
fireclay or other refractory material such interior may be further heated by intro-
ducing jets or currents of burning gas into it. The molten steel is poured into the
mould whilst the latter is thus being heated and the heat is continued until the
complete filling of the mould with the steel has been attained.
The process of compressing molten steel by means of hydraulic apparatus which
has been used for increasing the density of the steel may be applied in connection,

page_text: with my heated-mould system when it is desired to have the furnace shells or
other articles produced of very superior quality.
In carrying out my Invention according to one modification I cast the furnace
shell of such thickness and dimensious as to serve for being used in constructing a
boiler without further treatment; but I prefer, according to another modification
to cast the furnace shell of greater thickness than the intended finished thickness
and of different dimensions from the intended finished dimensions. Thus I prefer
to make the corrugations, in depth, one third greater than the finished depth, and
in form with one fourth of the pitch of each corrugation parallel to the axis of the
furnace shell. The furnace shell cast in this way is subjected to a rolling process
whereby the metal is compressed and modified so as ultimately to have the
intended finished thickness, dimensions, and form. For the rolling process two
rollers are at first employed, these being held in suitable frames or housings. The
frame at one end of the rollers is a complete frame with bearings for supporting the
roller journals and with adjusting screws for determining the distance between the
rollers. The other frame is made with separate parts for supporting the two
rollers and the part carrying the end of the roller which is to act inside of the
furnace shell is made movable to admit of the furnace shell being introduced and
removed. The two rollers act against each other one on the outside and the other
on the inside of the furnace shell. A third roller is also provided to be applied
either to the outside or to the inside of the shell and is adjusted in a position to
suit the intended finished dimensions and form of the furnace shell and so that the
furnace shell in rotating through the action of the other rollers will come in contact
with it and be made by it to take the proper curvature.
1004
EDMUND HUNT,
Applicant's Agent.
COMPLETE SPECIFICATION.
Improvements in Making Corrugated Boiler Furnace Shells of
Cast Steel.
I, JAMES GRAY LAWRIE, of 2 Westbourne Terrace, Glasgow, in the County of
Lanark, North Britain, Shipbuilder, do hereby declare the nature of my said
invention for "IMPROVEMENTS IN MAKING CORRUGATED BOILER FURNACE SHELLS
OF CAST STEEL," and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement, that is
to say :-
My said Invention has for its object the economical manufacture of weldless
corrugated furnace shells for steam boilers; and it consists in forming the shells by
casting them in an improved manner of a suitable quality of steel, and in further
treating the castings as hereinafter described.

page_text: For the purposes in view it is desirable that the steel shall be in a uniform
condition throughout and shall completely fill the entire mould or matrix in
which it is cast; and whilst these conditions are easily secured in cases in which
the steel is of considerable thickness or mass, there is a great liability in the case
of comparatively thin castings for the steel to become partly solidified before all
parts of the mould or matrix are filled, and for the castings to be imperfect. By
my Invention this difficulty is overcome by heating the moulds and keeping them
heated whilst the molten steel is being poured into them.
The moulds may be formed of suitable sand or other similar material in any
suitable kind of mould boxes; or they may be formed completely or partly of
firebrick or other solid refractory material, the parts of the moulds being held
together by casings or hoops; or the moulds may be formed completely or partly
of cast steel or cast iron the mould or matrix surfaces being prepared with a
suitable "blackening" or protective coating. When a mould has been prepared it
may be placed in a furnace or oven in which it may be heated up to the melting
point or to a temperature as near the melting point of the steel as can be used
without injuring the mould or its frame or binding hoops; and when the interior
of the mould is of fireclay or other refractory material such interior may be further
heated by introducing jets or currents of burning gas into it. The molten steel is
poured into the mould whilst the mould is thus being heated, and the heat is
continued until the complete filling of the mould with the steel has been attained.
The construction of mould and the manner of heating the same which I prefer
to adopt in carrying out my present Invention are described and shown in the
Complete Specification appertaining to my application for Letters Patent No 6220
of 1885.
The process of compressing molten steel by means of hydraulic apparatus which
has been used for increasing the density of the steel may be applied in connection
with my heated-mould system when it is desired to have the furnace shells produced
of very superior quality.
In carrying out my present Invention according to one modification I cast the
furnace shell of such thickness and dimensions as to serve for being used in
constructing a boiler without further treatment; but I prefer, according to another
modification to cast the furnace shell of greater thickness than the intended
finished thickness and of different dimensions from the intended finished
dimensions. Thus, I prefer to make the corrugations, in depth one third greater
than the finished depth and in form with the outer part to the extent of one
fourth of the pitch of each corrugation parallel to the axis of the furnace shell.
The furnace shell cast in this way is subjected to a rolling process whereby the
metal is compressed and modified so as ultimately to have the intended finished
thickness, dimensions, and form.
For the rolling process I use machinery of the kind-shown on the accompanying
sheet of explanatory drawings, figures, 1, and 2, of these drawings being respec-
tively an end and a side elevation. In this machinery two rollers, 3, 4, are first
employed, these being held in suitable end frames or housings, 5, 6, and being
provided with bearings and other parts arranged as usual excepting as hereinafter
described. The frame, 5, at one end of the rollers is a complete frame with
bearings for supporting the roller journals, and with an adjusting screw for
determining the distance between the rollers. The other frame, 6, is made with
stationary parts of the ordinary kind for supporting and adjusting the journal of
the upper roller, 3, whilst there is combined with it a movable part, 7, for supporting
the journal of the lower roller, 4, which is to act inside of furnace shell, this part
being made movable to admit of the furnace shell being introduced and placed on
the roller, 4, and removed therefrom. The movable part, 7, is in the form of a
plummer block made with a base plate, 8, fitted to rest and slide on the main
base plate, 9, of the machine; and a part of the main base plate is extended
outwards from the end frame, 6, to allow of the movable part, 7, being moved
away sufficiently to allow of the introduction and removal of the furnace shell.

page_text: When the movable part, 7, has been placed in position within the end frame, 6, it
is secured there by means of two spindles, 10, held in lugs formed for them on the
frame, 6, and fitted with handles, 11, for turning them these spindles having on
their lower ends heads with screw-like or inclined faces which become wedged
upon projecting surfaces formed for the purpose on the base, 8, of the block, 7.
In figure, 1, the furnace shell, 12, is shown of the size it has when first put into
the machine, and its finished size is indicated by dotted circles, 13. The two
rollers, 3, 4, act against each other one on the outside and the other on the inside
of the furnace shell, 12. A third roller, 14, is also provided to be applied to the
outside of the furnace shell, and is adjusted in a position nearer to or further from
the roller, 4, to suit the intended finished dimensions and form (13) of the furnace
shell, and so that the furnace shell in rotating through the action of the other
rollers, 3, 4, will come into contact with it and be made by it to take the proper
curvature. The third roller, 14, has its journals carried in blocks which are fitted
in inclined guides formed or fixed for the purpose on the frames, 5, 6; and these
bearing blocks are adjusted by means of screw spindles which have worm-
wheels, 15, fixed on their ends, these worm wheels gearing with worms on a
shaft, 16, which has a handwheel, 17, fixed on one end of it. If found desirable
another roller like the third roller, 14, may be introduced on the other side of the
machine to assist in confining the furnace shell and giving it the proper curvature.
The third roller, 14, or the third and fourth rollers when another is also used may
either be adjusted to suit the intended final size of the furnace shell, or it or the
pair may at first be adjusted nearer the inner main roller, 4, and be gradually
moved outwards as the furnace shell gradually enlarges with the rolling action.
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. The forming of corrugated boiler-furnace shells of steel by casting them in
heated moulds substantially as herein before described.
2. The forming of corrugated boiler-furnace shells of steel by first casting them
in heated moulds and subsequently rolling them substantially in the manner
hereinbefore described.
3. The rolling of cast-steel corrugated boiler-furnace shells by means of improved
machinery substantially such as is hereinbefore described.
TI 1000
EDMUND HUNT,
Applicant's Agent.