IMPROVE- MENTS IN THE MANUFACTURE OF COMPOUND PLATES OF HARD AND SOFT HOMOGENEOUS METALS
Year: 1882

page_text: LETTERS PATENT to Samuel Chatwood and Samuel Rawsthorne Chatwood
both of Bolton in the County of Lancaster for an Invention of "IMPROVE-
MENTS IN THE MANUFACTURE OF COMPOUND PLATES OF HARD AND SOFT
HOMOGENEOUS METALS
"
PROVISIONAL SPECIFICATION left by the said Samuel Chatwood and
Samuel Rawsthorne Chatwood at the Office of the Commissioners of Patents
on the 7th November 1882.
SAMUEL CHATWOOD and SAMUEL RAWSTHORNE CHATWOOD both of Bolton in the
County of Lancaster "IMPROVEMENTS IN THE MANUFACTURE OF COMPOUND
PLATES OF HARD AND SOFT HOMOGENEOUS METALS
"
Our Invention has for its object the manufacture of compound plates which
while being capable when hardened of resisting drilling tools and the impact of
shot will at the same time be free from the liability to spontaneous fracture
usually found in compound plates not capable of being drilled by tools or pierced
by shot
We prepare an ingot mould placing in it vertical partitions of thin metal so as
to divide the mould into three or more compartments three by preference. Into
the centre compartment we run homogeneous metal which when heated to redness
and plunged into cold water will be hard and brittle and into the outer compart-
ments we run homogeneous metal of such a quality that when heated to redness
and plunged into cold water will not become hard and brittle but remain ductile
and capable of being bent without fracture. The two metals are poured at the
same time and care is taken to maintain the same level in all the compartments.
The ingots so prepared we hammer or roll into slabs or plates-the plates are
worked to the desired forms and hardened which renders the centres secure from
being pierced while both exterior surfaces remain malleable and can be worked.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Samuel Chatwood and Samuel Rawsthorne Chatwood in the Great
Seal Patent Office on the 7th May 1883.
SAMUEL CHATWOOD and SAMUEL RAWSTHORNE CHATWOOD both of Bolton in
the County of Lancaster "IMPROVEMENTS IN THE MANufacture of cCOMPOUND 5
PLATES OF HARD AND SOFT HOMOGENEOUS METALS.
"
Our invention has for its object the manufacture of compound plates which
while being capable when hardened of resisting drilling tools and the impact of
shot will at the same time be free from the liability to spontaneous fracture
usually found in compound plates not capable of being drilled by tools or pierced I
by shot.
We prepare an ingot mould placing in it vertical partitions of thin metal so as to
divide the mould into three or more compartments three by preference. Into the
_centre compartment we run homogeneous motal which when heated to redness and
plunged into cold water will be hard and brittle and into the outer compartments 1
we run homogeneous metal of such a quality that when heated to redness and
plunged into cold water will not become hard and brittle but remain ductilo and
capable of being. bent without fracture. The two metals are poured at the same
time and care is taken-to-maintain the same-level-in-all the compartments.
The-ingots-so-prepared we bammer or roll into slabs.or plates_the_plates_are_2
worked to the desired forms and hardened which renders the centres secure from
being pierced while both exterior surfaces remain malleable and can be worked.
Figure 1 is a side elevation and Figure 2 is a transverse section of an ingot
mould which we employ in casting the compound plates.
The mould consists of two trough like blocks A, A; they are separated by 2
distance pieces B, B, and the whole is held together by hoops C, C, and wedges D, D.
In the joints between the parts A, A, and B, B, partitions of thin sheet iron E, E,
are nipped and held. Into the mould so prepared the metal of the two qualities
set for the above is poured as already described.
A modification of the mould is shown by the Figures 3 and 4. In this modi- 3
fication the mould consists of a trough like part G and a cover part H bound
together by the hoops K and the wedges L.
Within the mould a block M is contained, it occupies just the space which is
ultimately to receive the hard metal.
When the mould has been prepared in this way, the softer steel or homogeneous
inetal is first poured on either side of the block M; it immediately sets and then
as rapidly as possible the mould is opened, the block M is withdrawn and the mould
is closed up again. This done the other metal is at once poured in to fill the
vacant space.
The two sides of the part G of this mould are not quite parallel but incline 4
[slightly the one from the other as they approach the opening which receives the
cover part H. The ingot when cast and removed from the mould is hammered and
it is afterwards rolled down to the thickness required. This for the manufacture
of safes (which is the use we especially contemplate) will usually be from 14 inches
as a maximum to three eighths of an iuch as a minimum thickness.
After rolling the plates are hardened by heating and plunging in the usual way;

page_text: or rather the metal in the centre of the plate is thus rendered hard but the metal
on the exterior being incapable from its nature of being hardened remains ductile.
What we claim is the manufacture of compound plates of hard and soft
homogeneous metals substantially as described.
In witness whereof I the said Samuel Rawsthorne Chatwood have hereunto
set my hand and seal this fourth day of May in the year of our Lord
One thousand eight hundred and eighty three.