IMPROVEMENTS IN THE MANUFACTURE OF ARMOUR PLATES
Year: 1876

page_text: LETTERS PATENT to Gerard Wenzeslaus Von Nawrocki, of Berlin, in the Empire
of Germany, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF
ARMOUR PLATES." A communication by Messieurs Asbeck, Osthaus, Eicken,
and Company, of Hagen, Germany, aforesaid'
Sealed the 29th December 1876, and dated the 29th June 1876.
PROVISIONAL SPECIFICATION left by the said Gerard Wenzeslaus Von
Nawrocki at the Office of the Commissioners of Patents on the 29th June 1876.
GERARD WENZESLAUS VON NAWROCKI, of Berlin, in the Empire of Germany.
"IMPROVEMENTS IN THE MANUFACTURE OF ARMOUR PLATES,"
Hitherto in applying armour or metal plates to safes in order to give them
additional security against theives it has been the chief object to endeavour to
select such quality of armour plates as might best resist attacks by drills and files.
For this reason those most generally employed are made of thin hard steel plates,
and occasionally hardened cast plates are also used. Such plates have, however,
been found very liable to fracture from comparatively slight blows, and do not
therefore afford the requisite amount of resistance and consequent security desired.
Now the object of this Invention is to manufacture armour plates in the propor-
tion of one half of glass hard cast steel to one half of soft tenacious iron, which
plates are found not only impervious to fracture from blows, but also to resist all
attempts to be either drilled or filed.
To carry out this Invention I proceed as follows:-The main point in making
these improved armour plates is the preparing of a hard cast steel and of a very
tenacious soft iron in such a way that both metals are by force of welding, forging,
and rolling made into an inseparable unity. The cast steel is made of the best
and purest German spiegel irou, charcoal, raw steel, and a flux of dross by which
these metals whilst yet in fusion are thoroughly purified from copper and sulphur,
both of which are pernicious to their thorough and complete welding. Both metals
are melted in fire-clay crucibles under the high temperature of a gas furnace, care
being taken that the fire-clay of which such crucibles are made is thoroughly free
from either copper or sulphur.
The very thin melted metal is then cast into chills, and after being cooled as
raw block steel in a suitable reheating hearth, is then further wrought.
The requisite soft and very tenacious iron is manufactured of the purest Siegen
spiegel iron and Nassau charcoal, pig iron, with a flux of dross, manganese, and
Price GdI

page_text: chloride of sodium. These materials are melted in a suitable puddling furnace and
then carefully wrought into lumps. These lumps are then brought under the action
of a heavy steam hammer in order to get rid of all admixture of dross therein, and
then forged more compact.
In order to obtain the still greater degree of purity which is necessary for weld-
ing them with the cast steel the lumps are refined and then placed in the reheating
hearth. To ensure a very intimate union of the cast steel with the iron dovetail
holes or apertures are made in the blocks of steel while yet hot, in which enter
corresponding projections formed on the blocks of iron.
The iron is then heated in the reheating hearth to a welding heat and the cast
steel to a red heat, after which both metals are put together, the one on the other,
and thoroughly and strongly welded together with borax under a heavy steam
hammer.
The metal plates which are the result of this process are then again beated in a
plate fire and rolled between case hardened rollers to plates of about 3.13 mille-
metres in thickness, or to any other suitable thickness, after which they are heated
in a furnace to a red heat and hardened and flattened under strong hydraulic
pressure.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said Gerard Wenzeslaus Von Nawrocki in the Great Seal Patent Office on the
29th December 1876.
GERARD WENZESLAUS VON NAWROCKI, of Berlin, in the Empire of Germany.
"IMPROVEMENTS IN THE MANUFACTURE OF ARMOUR PLATES." A communication
by Messieurs Asbeck, Osthaus, Eicken, and Company, of Hagen, Germany, aforesaid.
Hitherto in applying armour or metal plates to safes in order to give them
additional security against thieves it has been the chief object to endeavour to
select such quality of armour plates as might best resist attacks by drills and files.
For this reason those most generally employed are made of thin hard steel plates,
and occasionally hardened cast plates are also used. Such plates have, however, been
found very liable to fracture from comparatively slight blows, and do not therefore
afford the requisite amount of resistance and consequent security desired.
Now the object of this Invention is to manufacture armour plates in the proportion
of one half of glass hard cast steel to one half of soft tenacious iron, which plates are
found not only impervious to fracture from blows, but also to resist all attempts to
be either drilled or filed.
To carry out this Invention I proceed as follows:--The main point in making
these improved armour plates is the preparing of a hard cast steel and of a very
tenacious soft iron in such a way that both metals are by force of welding, forging,
and rolling made into an inseparable unity. The cast steel is made of the best and
purest German spiegel iron, charcoal, raw steel, and a flux of dross by which these
metals whilst yet in fusion are thoroughly purified from copper and sulphur, both
of which are pernicious to their thorough and complete welding. Both metals are
melted in fire-clay crucibles under the high temperature of a gas furnace, care being
taken that the fire-clay of which such crucibles are made is thoroughly free from
either copper or sulphur.
The very thin melted metal is cast into chills, and after being cooled as raw block
steel is then further wrought in a suitably constructed reheating hearth, shewn at
Figures 1 and 2 of the accompanying Drawings.
The requisite soft and very tenacious iron is manufactured of the purest Siegen
spiegel iron and Nassau charcoal, pig iron, with a flux of dross, manganese, and
chloride of sodium. These materials are melted in a suitably constructed puddling
furnace, shewn at Figures 3 and 4 of the accompanying Drawings, and then carefully
wrought into lumps. These lumps are then brought under the action of a heavy

page_text: steam hammer in order to get rid of all admixture of dross therein, and then forged
more compact.
In order to obtain the still greater degree of purity which is necessary for welding
them with the cast steel the lumps are refined and then placed in the reheating
hearth before mentioned. To ensure a very intimate union of the cast steel with
the iron dovetail holes or apertures are made in the blocks of steel while yet hot, in
which enter corresponding projections formed on the blocks of iron.
The iron is then heated in the reheating hearth to a welding heat and the cast
steel to a red heat, after which both metals are put together, the one on the
other, and thoroughly and strongly welded together with borax under a heavy
steam hammer.
The metal plates which are the result of this process are then again heated in a
plate fire and rolled between case hardened rollers to plates of about 3.13 millimetres
in thickness, or to any other suitable thickness, after which they are heated in a
furnace to a red heat and hardened and flattened under strong hydraulic pressure.
Having thus particularly described and ascertained the nature of the said
Invention, and the manner of carrying the same into effect, I would have it under-
stood that I claim the manufacturing a new kind of armour plate, composed of cast
steel and iron, in such manner as to resist completely all attacks, either by drills,
files, or other implements, and also impervious to fracture from heavy blows,
substantially in the manner herein-before described and illustrated.
In witness whereof, I, the said Gerard Wenzeslaus von Nawrocki, have here-
unto set my hand and seal, this Twenty-ninth day of December, in the
year of our Lord One thousand eight hundred and seventy-six.
G. W. VON NAWROCKI. (L.S.)