Improvements in the Manufacture of Tubes for Cannon and Small Arms.
Year: 1896

page_text: Date of Application, 17th Aug., 1896-Accepted, 17th Oct., 1896
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Tubes for Cannon and
Small Arms.
We, CHARLES CHOLAT and HENRI HARKET, both of Le Marais St. Etienne
in the Department of Loire, France, do hereby deolare tho 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 :-
In manufacturing hollow pieces of cast steel, and in especial tabes for cannon,
and small arms the metal is at present merely elongated by the forging, and is not
turned around the axis of the tube. A tube so made is noticeably weak trans-
versely or perpendicularly to its axis in point of view of resistance and especially of
malleability in drawing.
Under the enormous pressures which on firing are produced inside the tube, the
metal is more fatigued perpendicularly to the axis than parallel to it and tends to
Bwell by increasing its diameter; forging by mere elongation therefore puts the
metal in a state unsuitable to the unequal strains to which it is subjected.
According to this invention the process of manufacture has for its object to
arrange the fibre of the metal in such a manner as to give it perpendicularly to the
axis a resistance aud malleability greater than or at least equal to those in a
parallel direction.
This process consists in submitting the forging after having given it approxi-
mately the requisite diameter and length to a torsion perpendicular to the axis and
proportional to the amount of twist desired, to be given to the fibres of the metal.
The forging being heated to redness is kept fixed at one end whilst the other is
twisted by the aid of an apparatus whose rotation is perpendicular to the axis; tho
axis of the forging being kept rectilinear.
The apparatus capable of carrying out this twist may be arranged in different
ways according to the size of the piece to be twisted, a description of this is
unnecessary, the operation being very simple.
Instead of twisting one ond only, a twist in opposite directions may be given to
each end.
The number of turns to be given to one end relative to the other may be from
a fraction to fifteen or twenty whole turns, a straight line traced on the forging in
the same plane as the central axis may thus become a helix passing round the axis
a great number of times.
In any case that which characterizes our invention is giving more or less torsion
to the forging, the axis being at the same time kept rectilinear, and the torsion
being greater in such or such portion of the forging as this portion has more or less
cross strain to support.
By the torsion, the molecules or crystals of the steel are elongated perpendicularly
to the axis, in other words the fibres of the metal are arranged as a cord wound in
a helix round the cylinder would be, and as is known this is of importance for the
good behaviour of metal under strain especially with special steels, nickel steel for
example.
The good arrangement of the fibre which is given to the metal by this process,
allows cannon to be made which have greater cross resistance and are not so liable
to burst as those forged without torsion.

page_text: Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
In the manufacture of tubes for cannon, small and other arms the process which
consists in submitting the forging to a torsion perpendicular to the axis and
proportional to the amount of twist desired to be given to the fibre substantially as
described.
Dated this 17th day of August 1896
CARPMAEL & Co.,
Agents.