Improvements in the Manufacture of Explosive Projectiles.
Year: 1891

page_text: Date of Application, 17th Apr., 1891
Complete Specification Left, 19th Dec., 1891-Accepted, 23rd Jan., 1892
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Explosive Projectiles.
I, THOMAS ELWELL, of 194, Avenue de Paris, Plaine Saint Denis (Scine)
France, Engineer, do hereby declare the nature of this invention to be as
follows:-
My improvements in the manufacture of explosive projectiles relate to armor-
piercing shells which are usually made of cylindro-conical or ogival-headed form
with an internal cavity, to contain the explosive charge, closed by a screw plug in
the base.
Hitherto this cavity has been formed either by (1) turning or boring out the
metal by means of a cutting tool, an operation which involves waste of the metal
represented by the boring; (2) by stamping and drawing the metal in a heated
state in dies, whereby waste of material is to a great extent avoided, but on the
other hand the metal suffers considerable loss of strength during the operation,
which is a great consideration in the case of armor-piercing shells.
According to my invention, the projectile is made entirely by forging in such
manner that the different parts of the projectile, namely the ogival head, body, and
base, of the projectile possess in the highest possible degree the essential qualities
which those parts of the projectile should possess, riz. (a) maximum hardness at the
ogival head whereby the greatest possible penetrative power is obtained (b) a lesser
degree of hardness at the body portion, to avoid breaking up of the projectile on
striking a plate (c) great toughness at the base in order to prevent its becoming
detached in consequence of the motion of the projectile being suddenly arrested on
striking.
To this end my improved process of manufacture comprises the following series
of operations: A piece of steel of a weight slightly greater than that of the shell
to be made is first cut off from a round bar of a diameter suited to the size of shell
required. The ends having been prepared to facilitate subsequent centreing of the
work in the tools, the cavity is formed by placing the metal white hot in a mould
of a form to be given to the rough shell and forcing into it a core plunger or suc-
cession of core plungers whereby the mass is hollowed and forced out to the form
of the mould at the same time that the head is strongly compressed, the form of the
mould being such as that the metal will be wrought to the degree of hardness
required at the different transverse sections of the shell; regard being also had to
the shrinkage which will take place when the pressure ceases and the temperature
falls. The mould is formed at the upper end with an enlargement of suitable form
to receive the metal which, in the next operation, is to form the base of the shell in
which the plug is to be screwed.
The
The mould is represented in section at bb, Figure 1 of the accompanying drawings
in which a a is the enlargement referred to whereby the first form given to the
shell is such that, in the case of small and medium sized shells, a base of great
strength is obtained, longitudinal drawing of the metal being avoided.
mould is provided with a movable cover which serves as a guide for the core
plunger, closes the mould, and acts as a taker-off. The number of core plungers
used in succession would depend on the calibre and the quality of the steel. Under
a relatively slight pressure, the metal fills all parts of the mould and when it can no
longer flow, it is squeezed and wrought until the ogival head is compressed to the
desired degree and the body and base receive the exact amount of preparation for
resisting the strains to which they will be exposed. For small and medium sized
shells, the core plunger is of conical form and in a single piece and the base would
not be formed but only indicated by the flange or extra thickness of metal above

page_text: referred to. For shells above a certain calibre a series of plungers are employed,
formed in several pieces each capable of passing through the aperture in the base,
the form and diameter of which are determined in this second operation.
The next operation consists in contracting the flange formed at the base of the
shell so
as to reduce its diameter by forcing the metal radially inwards to
form the seat for the plug. In this pressing operation or operations, from the
circumference towards the centre, the conical exterior is brought to the cylindrical
form, for the body of the projectile. In the case of large shells, the closing-in of
the base will have been commenced in the previous operation so that there will be
no more to do, in order to contract the opening in the base, than is done by
ordinary forging in a press or under the hammer, an operation which is always
necessary for imparting the desired qualities to the metal. After this operation,
the shell will have approximately received its final form, as shewn in Figure 2 in
which a a is the body and the cavity in the shell. The remaining operations of
screw-threading the hole for the plug, and tempering, etc., are performed as in
ordinary.
By the improved process of manufacture herein described, the chamber of a
forged steel shell may be made of a form other than circular. With this form, the
sides of the shell have approximately the same thickness at all points in the same
transverse section, whereas, by my improved method, the chamber may be made of
forms more favorable for resisting concussion coupled with greater facility for
bursting, as has been practised in casting shells. For this it is only necessary that
the core plunger should be of straight or convex sided conical form to allow of
withdrawing the plunger. When, however, it is of such size as to necessitate
being made in segments connected together, the variety of profiles which may be
given to the cavity is practically unlimited.
Figure 3 shews a cross-section of one form of cavity which may be produced
either with a solid or a built up plunger. It is star shaped, with the angles rounded
off.
The advantages obtained by this improved process of manufacture and of the
special forms of cavities are as follows:-Increased hardness and tenacity of the
metal economy of material; greater facility for forging with a plunger and a
more perfect result as the conical form of the shell blank with its external flange
enables heavier, and consequently stronger, plungers to be used; reduction in the
cost of manufacture and, in the case of chambers of star-shaped section, greater
resistance to concussion and easier bursting.
Dated this 17th day of Auril 1891
T. ELWELL,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Explosive Projectiles.
1, THOMAS ELWELL of 194, Avenue de Paris, Plaine Saint Denis (Seine)
France, Engineer, 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 :-
My improvements in the manufacture of explosive projectiles relate to steel
armour-piercing hills which are usually made of cylindro-conical or ogival-headed
form with an internal cavity to contain the explosive charge, closed by a screw
plug in the base.
Hitherto this cavity has been formed either by (1) turning or boring out the
metal by means of a cutting tool, an operation which involves waste of the metal
corresponding to the amount of the boring besides which the metal is in no-wise
improved by boring it in a cold state (2) by stamping and drawing the metal in a

page_text: heated state in dies whereby waste of material is to a great extent avoided but on
the other hand the metal suffers considerable loss of strength during the operation
which is a great consideration in the case of armour-piercing shells.
According to my invention the projectile is made entirely by forging in such
manner that the different parts of the projectile, namely the ogival-head, body and
base, acquire in the highest possible degree the essential qualities required for
those parts, riz.
(a) maximum hardness at the ogival head whereby the greatest possible pene-
trative power is obtained
(b) a lesser degree of hardness at the body portion to avoid breaking up of the
projectile on striking a plate
(c) great toughness at the base in order to prevent it becoming detached in
consequence of the motion of the projectile being suddenly arrested on
striking.
To this end my improved process of manufacture comprises the following series
of operations: A piece of steel of a weight slightly greater than that of the shell
to be made is first cut off from a round bar of a diameter suited to the size of shell
required. The ends having been prepared to facilitate subsequent centreing of the
work in the tools the cavity is forined by placing the metal while hot in a mould
of a form to be given to the rough shell and forcing into it a core plunger or
succession of core plungers whereby the mass is hollowed to form the cavity and
forced out to the form of the mould at the same time that the head is strongly
compressed, the form of the mould being such that the metal will be wrought to
the degree of hardness required at the different transverse sections of the shell,
regard being also had to the shrinkage which will take place when the pressure
censes and the temperature falls. The mould is formed at the upper end with an
enlargement of suitable form to receive the metal which in the next operation is to
form the base of the shell in which the plug is to be screwed.
The mould is represented in section at Figure 1 of the drawings accompany-
ing my Provisional Specification in which aa is the enlargement referred to
whereby the first form given to the shell is such that in the case of small and
medium sized shells a base of great strength is obtained, longitudinal drawing of
the metal being avoided and the advantage of an annular forging ensured. The
mould is provided with a movable cover which serves as a guide for the core
plunger, closes the mould and acts as a taker-off. The number of core plungers
used in succession would depend on the calibre and the quality of the steel. Under
a relatively slight pressure the metal fills all parts of the mould and when it can no
longer flow it is squeezed and wrought until the ogival head is compressed to the
desired degree and the body and base receive the exact amount of preparation
for resisting the strains to which they will be exposed. For small and medium
sized shells the core plunger is of conical form and in a single piece and the base
would not be formed but only indicated by the external flange or extra thickness of
metul above referred to. For shells above a certain calibre a series of plungers are
employed formed in several pieces each capable of passing through the aperture in
the base the form and diameter of which are determined in this second operation.
The next operation consists in contracting the external flange formed at the base
of the shell so as to reduce its diameter by forcing the metal radially inwards to
form the seat for the plug. In this pressing operation or operations from the cir-
cumference towards the centre the conical exterior is brought to the cylindrical
form for the body of the projectile. In the case of large shells the closing-in of the
base will have been commenced in the previous operation so that there will be no
more to do in order to contract the opening in the base than is done by ordinary
forging in a press or under the hammer, an operation which is always necessary for
imparting the desired qualities to the metal. After this operation the shell will
have approximately received its final form as shewn in Figure 2 in which a a is the
body and the cavity in the shell. The remaining operations of screw-threading
the hole for the plug and tempering, etc., are performed as in ordinary.

page_text: By the improved process of manufacture herein described, the chamber of a
forged steel shell may be made of a form other than circular. With this form the
sides of the shell have approximately the same thickness at all points in the same
transverse section, whereas by my improved method the chamber may be made of
forms more favorable for resisting concussion coupled with greater facility for
bursting as has been practised in casting shells, it being only necessary that the
sides of the core plunger should be straight or convex and more or less divergent to
allow of withdrawing the plunger. When however the core plunger is of such size
as to necessitate being made in segments connected together, the variety of profiles
which may be given to the cavity is practically unlimited.
C
Figure 3 shews a cross-section of one form of cavity c which may be produced
cither with a solid or a built-up plunger. It is star-shaped with the angles
rounded off.
The advantages obtained by this improved process of manufacture and of the
special forms of cavities are as follows-
Increased hardness and tenacity of the metal ;
Economy of material;
Greater facility for forging with a plunger and a more perfect result, as the
conical form of the shell blank with its external flange enables heavier and
consequently stronger plungers to be used;
Reduction in the cost of manufacture and in the case of chambers of star-shaped
section greater resistance to concussion and easier bursting.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
1st. The process of manufacture of explosive projectiles as herein described.
2nd. The operation of forging the rough shell from a blank of such an external
form in a mould of such internal form and with the aid of a succession of conical
plungers of such form that a rational forging of all parts of the projectile will be
obtained and the cavity of the shell will be such as to permit of the introduction
and withdrawal of plungers of sufficient size to resist the forging pressure, even in
the case of small projectiles.
3rd. Forging small projectiles with an external flange and then closing-in the
flanged portion to form the base in a press or under the hammer, as herein
described.
4th. Forming the chambers of forged steel armour-piercing shells with
longitudinal reinforcing ribs alternated with grooves to facilitate bursting.
5th. The application of the herein described improvements for the manufacture
of forged shells of all calibres and forms.
Dated this 19th day of December 1901.
T. ELWELL,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.