Improved Manufacture of Hollow Projectiles.
Year: 1893

page_text: Date of Application, 18th Oct., 1893-Accepted, 18th Nov., 1893
CUMI LEIE DI BOLTIVAT
Improved Manufacture of Hollow Projectiles.
We, EDWIN CLAPHAM, of Claramont, Cheshunt, in the County of Herts,
ALEXANDER JOHN DUDGEON, of 112, Fenchurch Street, in the County of
London, and THOMAS FIRTH, of 31, Mellish Street, Millwall, in the County of
Middlesex, do hereby declare the 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 :-
This invention relates to an improved manufacture of hollow projectiles, such
as steel shells, by the combined operations of pressing in dies, punching and
drawing.
All attempts heretofore made to manufacture hollow shells by the said combined
operations have been more or less unsuccessful because, owing to the form of the
blanks employed, and the form of the dies in which they were moulded into the
required shape, it was not possible to insure the metal flowing in the exact direction
required, resulting in irregularities in the manufacture which rendered the product
practically useless.
According to the present invention these defects are obviated in the first place by
making the blank to be operated upon, not of a flat disc-shape as heretofore
proposed, but in the form of a solid cylinder which is of a length greater than its
diameter, and the weight of which exceeds to a greater or less extent the weight of
the projectile to be produced, and in the second place, in converting this blank at
once, by the first operation of pressing in a die, into a body composed of a conical
or conoidal part approximating more or less in shape to that of the ogival head of
the finished shell, and of a cylindrical or slightly tapering part that represents the
body of the shell, the extremity of this part having a hollow formed in it by the
head of the punch employed.
as to
Having obtained this configuration in the first instance, the body is then
preferably subjected to a second pressing operation in a die, so
approximate the head still more to the ultimate shape, to extend the cylindrical
part somewhat and to deepen the hollow therein, after which the body is subjected
in the known manner to a series of consecutive drawing operations whereby it is
brought by degrees to the configuration and dimensions required, and lastly it is
brought to the exact configuration by a final pressing in a die, by cutting off the
excess of metal at the rear end so as to bring it to the exact weight required, and
lastly, when required, by closing in the rear end by any suitable known means for
this purpose.
On the accompanying drawing A Fig. 1 represents by way of example a
cylindrical blank which may be conveniently cut off a round steel bar of the
required diameter, and which is of a greater length than its diameter, while
its weight exceeds that of the finished shell to the extent, say, of from 15 to
25 per cent.
This blank being heated up to the proper forging heat, is then placed in a die of
the form shown in the vertical section at Fig. 2, that is to say, having a part a
which is cylindrical, a part 6 which is slightly tapering in diameter towards the
lower end, and a part c which is conical or conoidal, at the apex of which is in some
cases formed a hole for the introduction of an extractor.
The cylindrical part a of the die being sufficiently larger in diameter than the
blank A to allow of its easy introduction, the blank is dropped in so as to bear with
its lower end upon the upper end of the conical part c as shewn, and a punch C,
which accurately fits the cylindrical part so as to be effectually guided thereby, is
then driven in, either by hydraulic or other pressure or by the blow of a steam
hammer, the lower end of the punch being formed with a flat shoulder and a central

page_text: projection e having bevilled edges as shewn. On driving this punch in until the
moving part of the press comes in contact with a stop, the punch forces the blank A
into the parts bc of the mould, the close fit of the punch in the part a preventing
the escape of any of the metal upwards, so that the blank is forced to assume
accurately the shape of the parts b, c, while at the same time, the projection e in
penetrating into the upper end of the blank, assists in causing the metal to
accurately fill out the shape of the die, and leaves a corresponding recess, so that
when the forging is removed from the die it will be of the shape shewn in vertical
section at Fig. 3. namely having a conical or conoidal head c¹ and a cylindrical or
slightly tapering part with a central cavity g.
By means of a precisely similar operation with a second die and punch, the forging
is then brought to the shape shewn in vertical section Fig. 4, where the head c² still
further approximates to the finished shape, and the slightly tapering part 62 is
extended and its recess g² deepened.
The forging is now subjected to the known drawing cutting and pressing operations
as first above mentioned in order to bring it into the finished form.
According to a modification of the above described mode of proceeding, we bring
the blank at once into a form similar to that shewn at Fig. 4. by the employment of
a die and punch of the form shewn at Fig. 5; the die is here again formed with a
cylindrical part a³, a slightly tapering part 6³, and a conoidal or approximately
ogival part c³, in a similar manner to Fig. 2, but the punch C₁ has an extended
projection e with rounded end, the projection being made of such a length in
proportion to the die and the size of the blank, that when this is dropped into the
mould in the same manner as at Fig. 2 and the punch is forced down, the
projection e in penetrating into the metal not only forces the blank down in
the die but at the same time in displacing the upper part of the metal laterally,
causes it to rise up in the die round the projection e', the length of the latter being
sufficient to leave the metal perfect freedom to do so without coming in contact
with the flat annular face of the punch, even when this has been forced down
to its lowest position as shewn at Fig. 5, the cylindrical part of the punch
serving in this case merely to guide it accurately in the cylindrical part a³ of
the die, and not, as in the first arrangement, to force the metal of the blank
downwards.
Thus the forging is at once brought into the more or less elongated form shewn,
similar to that shewn in Fig. 4 produced by the second operation previously
described, after which the projectile is completed by drawing operations &c. as
above stated.
In cases where the removal of the forging from the dies is effected otherwise
than by an extractor operating at the lower end of the die, the opening in the latter
is not required and the stud shaped extension shewn on the head c c² would not
then occur.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:
A manufacture of hollow forged projectiles wherein a blank whose length
exceeds its diameter and whose weight exceeds that of the finished shell, is
operated upon by a die and punch in such manner as to convert it into a forging
having a conical or conoidal part approximating to the form of the head of the
projectile and a cylindrical or slightly tapering part, representing the body of
the projectile and having a recess formed in it, such forging being then subjected
to known operations for converting it into the finished projectile, substantially as
described.
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