A New or Improved Process and Apparatus for or relating to the Manufacture of Armour-plates.
Year: 1892

page_text: Date of Application, 16th Dec., 1892-Accepted, 21st Jan., 1893
COMPLETE SPECIFICATION.
A New or Improved Process and Apparatus for or relating to the
Manufacture of Armour-plates.
I, ALFRED LONGSDON, of 75 Old Broad Street in the City of London, Civil
Engineer, do hereby declare the nature of this invention (a communication to me
from abroad by the firm of Fried Krupp of Essen in the Empire of Germany Cast
Steel Manufacturers) and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement :-
It is known that iron deficient in carbon can be very quickly carburetted by
passing hydrocarbon gases over the same, and according to this invention I utilize
this knowledge as hereafter described for the purpose of giving a hard surface to
one face of otherwise soft armour plates of all kinds.
This invention will be readily understood by the following description having
reference to the accompanying drawings, on which at Figure 1 is shewn in a
diagrammatic manner and in vertical longitudinal section, a furnace constructed in
a suitable manner whereby this invention may be conveniently carried into effect.
Figure 2 is a transverse section, and Figure 3 is a horizontal section of the same
furnace; Figure 4 is a longitudinal section, and Figure 5 a transverse section
shewing a modified form of furnace suitable for effecting a somewhat varied mode
of carrying out the said invention; Figure 6 is a similar view to that shewn at
Fig. 5, but with the furnace cover removed.
Figs. 1, 2, and 3 of the accompanying drawing illustrate one form of apparatus
in which two plates are carburetted simultaneously, but it is obvious that the said
apparatus may be variously modified.
The furnace A is heated by gas which enters by the passage a, whilst the air is
supplied by the passage b. The products of combustion escape by two passages c
that are situated on either side of the door d. The hearth B of the furnace is
capable of being traversed out from the latter, say on rails as shewn. The first
plate C to be carburetted is laid with the face to be carburetted uppermost, upon
supports or pillars e on the hearth of the furnace, the said hearth having been
traversed out of the said furnace, whilst a second plate D is laid with the face to
be carburetted downwards, upon the first plate, and is held at a small distance
from the latter by means of intermediate pieces of iron f, stone, or other suitable
material. When so placed both plates have walls g g h i built round them, so that
the space between the two armour plates is completely closed with the exception of
two holes in the wall and two larger holes in the wall i, whilst the gases can
pass freely along the plates exteriorly above and below the same, the gases
through openings m formed in the walls h and i.
passing under the plate
After the two plates have been built up in this manner on the hearth, the latter
is traversed into the furnace, and the latter is heated, until the plates are at about
the melting temperature of copper, whereupon pipes n and o, the positions of which
are indicated at Fig. 1, are passed through two openings in the furnace door into
the holes in the wall i, and hydrocarbons, illuminating gas, paraffin-vapour,
petroleum-gases, or the like, are passed through said pipes in between the plates.
The surfaces of the plates become carburetted by the action of these gases in a.
comparatively short time, whilst the used gases deprived of a large proportion of
their carbon, pass through the openings k in the wall into the furnace and burn
there. As soon as the carburation of the plates has reached the desired degree,
the hearth is run out and the plates are hardened in water by dipping or by
spraying the parts to be hardened, or it may be in oil.
The same arrangement as employed, according to this invention, for carburetting
with hydrocarbons, may be also employed for carburetting with solid carbon or the

page_text: like, by merely filling the space therewith between the two armour plates into
which the gas would otherwise enter. The holes k and I, and the supports between
the plates, are dispensed with in this case. This method of hardening two plates
together with solid carbon is an important improvement on the heretofore usual
method of carburetting one plate only at a time. The faces of the plates exposed
.to the flame are in both methods preferably protected by a light suitable
covering.
Armour plates may also according to this invention, be carburetted on one face
in, an advantageous manner by dipping the highly heated plates for a sufficient
length of time on one face into liquid cast iron, and then hardening in water or oil.
Figures 4, 5 and 6 illustrate an apparatus in which this method can be carried
into effect. The said method is however, limited to plates which have not too great
a curvature.
An iron bath is melted in the reverberatory furnace A', and the plate to be
carburetted is heated in another furnace. Then the cover B₁ of the furnace Ai is
lifted off, and the armour-plate C, suspended by screwed-in hooks, eye-bolts, or
like devices a from a crane, is dipped with the face to be carburetted into
the molten iron for a sufficient time. In this case the furnace A' may, after the
dipping operation, also be closed at the top and be further heated during the
carburation of the plate.
Armour plates may be carburetted on one face, according to this invention, by.
moulding a narrow space over the face of the plate to be carburetted, which space,
after the plate with the mould has been suitably heated, is filled by pouring suitable
cast iron into the same, so that a layer of cast iron of comparatively small thickness
is formed on that face of the plate which is to be carburetted. The pouring in of
the cast iron may be effected whilst the plate, together with the mould, is located
in the furnace described in connection with the preceding method, the vaulted or
domed top or roof of the furnace being lifted off for this purpose. After the
pouring in of the cast iron, the furnace top is replaced and "heating is continued
until the cast iron has given up so much carbon to the soft plate, that the surface
of the cast iron is converted into extremely hard steel.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed I declare that what
I claim is :-
1. The new or improved process of manufacture of armour plates hardened 'on
one face only, and composed of wrought iron, ingot iron, or soft steel, or of alloys
of iron or steel with other metals, such as nickel, chromium, and the like, according
to which process carbon is supplied to the surface of the comparatively soft plates
to be carburetted (the said plates having been previously built into a furnace and
brought to a glow heat) by passing hydrocarbons such as illuminating gas, paraffin-
vapour, petroleum-vapour, or the like, or other carbonaceous gases over said
surfaces, the said plates being finally hardened in water or oil, substantially as
set forth.
on
2. In the process of manufacture of armour plates hardened
one side
substantially as specified in Claim 1, carburetting two plates at one and the same
time, by building the said two plates, with the faces to be hardened, facing each
other, into the furnace, heating same, and introducing the bydrocarbons into the
closed intermediate space between the two plates at one side, and allowing the
same to escape through smaller openings on the other side after the carbon has
been given up, substantially as set forth.
3. In the manufacture of armour plates hardened on one side only, the simul-
taneous carburetting of two plates, the said two plates being built into the furnace
with their faces to be carburetted facing each other, and the space between filled
with solid carbon, all constructed and acting substantially as and for the purposes
herein set forth.
4. In the manufacture of armour plates hardened on one side only, effecting the

page_text: carburation thereof by means of cast iron, by raising the plates to be treated to a
glow heat, and dipping same with the faces to be hardened into a bath of molten
cast iron for a sufficient time, whilst the other face remains outside of the cast iron,
and substantially as hereinbefore described.
5. In the manufacture of armour plates hardened on one face only, claimed by
Claim 4, in such a manner that a thin layer of suitable cast iron is poured upon
the face of the sufficiently heated plate to be carburetted, and the plate is then
kept hot for a further length of time, until the carbon of the cast iron welding or
becoming incorporated therewith, has penetrated so far into the plate that the
surface of the cast iron has become converted into very hard steel, and substantially
as herein described.
Dated this 16th day of December 1892
ALFRED LONGSDON.
Brewer & Son,
33, Chancery Lane, London.