Improvements in the Manufacture of Armour Piercing Steel Projectiles.
Year: 1889

page_text: Date of Application, 1st Mar., 1889
Complete Specification Left, 9th Oct., 1889-Accepted, 23rd Nov., 1889
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Armour Piercing Steel
Projectiles.
I, ROBERT KIDD, of No. 8 Campbell Terrace Brookhill Road Woolwich in the
County of Kent, England Engineer do hereby declare the nature of this invention
to be as follows:―
This invention has for its object, the preservation, of Forged steel Armour piercing
shot or shell, (after being machined to required dimensions), from rupture, or
cracking, throughout the entire process, of heating and hardening, and finally
producing, such a well balanced condition of such bodies, as to render them safe from
cracking, by sudden changes in temperature, and each such projectile, being hardened
alike.
To carry out my invention, I encase the bodies to the extent required, in ordinary
moulding sand, loam, or any other convenient material, coming within the category,
of non-conductors of heat, filling the interior of shell, with the same material, said
material being retained, in a suitable cylinder, of cast iron, or any other metal, or
material, capable of containing, and confining, the non-conductor in proper position,
and contact with bodies of such projectiles.
The cylinder, containing the non-conductor; is provided with a solid bottom. in
proportion to wall of same, on this bottom, is placed a bed of moulding sand, or loam,
or other material; upon which, the base of the projectile is placed, the space between
outside of body of projectile, and inside of cylinder, being then filled in with sand &c..
&c.. to required height.
The projectile encased as described, is then placed in a Muffle Furnace, (which may
be heated, with either coal or coke, the latter being preferable, where sufficient draught
is available, to ensure proper combustion) door of furnace closed, to exclude any
cooling action, from outside; and the projectile, or projectiles, left to be heated, to
the required temperature, which may either be arranged, by time or appearance.
viz. Head a bright red heat, declining to almost a black. in proximity to top of
cylinder.
By the foregoing means, the bodies are never allowed, to exceed a black heat, and
such heat is transmitted from. head only, in the process of heating. By this means
also, bodies are left in a proper condition, for assimilating themselves, to the condition
of heads, on sudden immersion of the latter, in the medium employed for cooling.
(Hardening) and instead of leaving a red hot body, exposed to the atmosphere, while
head is being cooled, thereby inducing unequal strains, the action of the cooling
medium on the red hot head, and the atmosphere on the black hot bodies, brings about
that assimilation of parts, necessary to prevent rupture.
The projectile, or projectiles, having been heated as described, is removed from
furnace, and suspended in a vertical position, point downwards, with suitable
appliances, (if a shell, the sand, loam, &c., in interior is allowed to remain) the heads,
and that portion of bodies required to be hardened, is then immersed (dipped) in
water, (which has previously been heated, to a temperature, of from 60° to 80°) to
that part of body, which has been heated red only, and moved (swung) to and fro in
the water, in this position.
If allowed to remain in this position, until head is cooled too much, a defined trans-
verse line of hardening, will be produced, after however allowing the projectiles, to
remain in the water, at the level indicated, for from 30 to 40 seconds, they are slowly
raised, until water is level with radius line of heads, repeating this operation, until
heads, 'are sufficiently cooled, to admit of the entire projectile being immersed, by this
D
027

page_text: -means, the line of hardening is sloped from a point, one, or more, inches below radius
line of Heads outside, to radius line of heads inside; and have all the appearance and
properties, of chilled cast iron projectiles.
Having sufficiently cooled the heads as before described, the projectiles are then
suspended, in a horizontal position, (sand in interior, having now been removed,) and
entirely immersed in same water, (thus cooling interior) and allowed to remain, until
temperature is reduced, to that of water, when the entire operations of heating, and
hardening, is completed.
Projectiles of this description, are so controlled, throughout the operations herein
described, as to ensure,
1st. Immunity from scaling.
2nd. Absolute uniformity of hardness, in each article.
3rd. Hardening confined to any point required.
4th. Prevention of undue strains, through unequal contraction, so fatal to Forged
steel Armour piercing projectiles, passing through this stage.
Dated this 28th day of March 1889.
QUUMI NINI MUITIOALION
Improvements in the Manufacture of Armour Piercing Steel
Projectiles.
I ROBERT KIDD, of 8 Campbell Terrace, Brookhill Road, Woolwich, in the
County of Kent, 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:-
This invention relates to an improved manner of producing hardened steel projectiles
for Armour piercing, the salient feature being the mode of heating the projectile for
hardening and tempering purposes. Projectiles treated by this invention are produced
in such a well balanced condition of hardness and temper as to render them safe from
cracking from sudden changes of temperature and to be capable of piercing the hardest
compound plates without breaking and also to enable large quantities of projectiles to
be hardened and tempered in a perfectly uniform manner.
In carrying out my invention I proceed as follows. I take a projectile after being
machined to required dimensions and encase that portion of the body that is not
required to be hardened, in ordinary moulding sand, loam or other suitable material
coming within the category of bad conductors of heat, held in a suitable mould or box
preferably of cast iron. If the projectile is a shell I fill the interior with the same
material.
The accompanying drawing represents a sectional view of a shell encased in moulding
sand as described, A being the box. B the sand C the shell. The projectile encased as
described is then placed in a muffle furnace, of usual construction preferably heated
with coke, if sufficient draught is available, and left to be heated to the required tem-
perature for dipping, that is the head part a bright red heat.declining to almost a black
at top of sand. The projectile having been heated as described is removed from
furnace and sand, and suspended by suitable holding appliance, point downwards, (if
a shell the sand in interior is allowed to remain) the head and that portion of the body
required to be hardened is then immersed inwater (of a temperature of from 60° to 80°)
down to that part of the body which has been heated red only, and stirred round in
the water, after allowing the projectile to remain in this way in the water for from 30
to 40 seconds (if allowed to remain in the water until the head is cooled too much a
'defined transverse line of hardening will be produced.) when it is slowly raised until
the water is a level with the radius line. of head, shown at line a. b. in drawing,
the dipping is again repeated as before until the head is sufficiently cool to admit of the
entire projectile being immersed in oil as hereafter described. By this means the line

page_text: size of projectile, then lifting the projectile partially out of the water, and dipping
again as before until the head part is sufficiently cooled when the sand from interior
is withdrawn, and the entire shell immersed in oil until its whole temperature is
reduced to that of the oil, substantially as described.
Dated this 9th day of October 1889.
FREDERIC PRINCE.
1, Quality Court, Chancery Lane, London, W.C., Agent for Applicant.