Year: 1887

page_text: Date of Application, 23rd Apr., 1887
Complete Left, 23rd Jan., 1888
Complete Accepted, 2nd Mar., 1888
1 ROBERT LOW of the Royal Laboratory, Woolwich Arsenal, in the County of
Kent, Engineer do hereby declare the nature of this invention to be as follows:-
My invention relates to steel projectiles and comprises an improved process or method
of hardening or tempering the same.
The hardening or tempering of armour-piercing projectiles has heretofore been
usually effected by heating them to the required temperature and then dipping them,
or wholly or partially immersing them in water or other liquid.
It has been found, however, that this method of hardening or tempering such articles
as projectiles, though efficient in respect of imparting the required hardness to the steel,
is attended with the serious disadvantage of frequently splitting or cracking the metal
and thereby destroying a projectile after the entire cost of its manufacture has been
incurred.
My invention affords the means for effectually hardening or tempering the projectiles
without the use of water or other liquid, and obviates the risk of injuring or destroying
the projectiles in the manner above described.
In hardening or tempering a projectile according to my said invention, I proceed
as follows, that is to say, I heat the said projectile to the required temperature and
place the same (preferably in a vertical position with its conical end downward) in a
mould of iron or other metal of the same, or approximately the same dimensions and
shape or configuration as the projectile or a portion thereof. While the projectile is
in this mould, I subject it to pressure by means of hydraulic or other power. This
pressure is maintained until the projectile-is cold, or nearly cold; and the projectile is
then removed from the mould.
I find it advantageous to use a mould having a central hole or recess into which the
point of the projectile will enter.; I thus avoid liability to injury of the point in the
operation of placing the projectile in the mould. Moreover the said hole permits
the escape of any scale, dust or the like which may be introduced into the mould with
the proiectile.
'

page_text: The mould must be of greater or less depth according to the length of the portion
of the projectile which it is desired to harden or temper. If the entire surface of the
projectile is to be hardened, the cavity in the mould should be of the same, or nearly
the same depth or length as the projectile.
In some instances, I employ a mould in which the projectile lies horizontally; this 5
mould is made in two parts or halves, in one of which the projectile is to be laid and
the other of which is to bo placed over the said projectile: and I apply pressure to the
projectile, while in the said mould, in a direction at right angles to its axis.
Whatever may be the construction of the mould, it should be made to conform to,
or fit the oxterior of the projectile, and the projectile therein should be kept under
pressure, so that there may be close contact between all parts of the surface to bo
hardened and the mould, and the heat of the red hot mass of metal may be conducted
freely away through the body of the said mould.
Dated this 23rd day of Anril 1887
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.

page_text: I, ROBERT LOW, of the Royal Laboratory, Woolwich Arsenal, 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 he particularly described and ascertained in and by the
following statement:-
My invention relates to steel projectiles and comprises an improved process or
method of hardening or tempering the same, so that their strength and penetrativeness
are greatly increased as compared with those hardened or tempered by the methods
hitherto adopted.
The hardening or tempering of armour-piercing projectiles has heretofore been
usually effected by heating them to the required temperature and then wholly or
partially inmersing them in oil or other liquid. It has been found, however, that this
method of hardening or tempering such articles as projectiles, though efficient in
respect of imparting the required hardness to the steel at or near the surface of the
projectile, is attended with the serious disadvantage of liability to splitting or cracking
of the metal and consequent destruction of the projectile after the entire cost of its
manufacture has been incurred.
My invention affords the means for effectually hardening or tempering the projectiles
without the use of water or other liquid, and, at the same time, compressing or
condensing the metal thereof; moreover it obviates the risk of injuring or destroying
the projectiles in the manner above described.
In hardening or tempering a projectile according to my said invention, I proceed
as follows, that is to say. I heat the said projectile to the required temperature and
place the same (preferably in a vertical position with its conical, conoidal or ogival
end downward) in a supporting die or mould, of cast iron or other suitable material,
the cavity in which is of the same, or approximately the same dimensions and shape
or configuration as the projectile or a portion thereof. When cominencing operations,
the mould is preferably heated (say to a temperature of from two hundred to three
hundred degrees Fahrenheit) before a projectile is inserted, in order to avoid chilling
of the surface of the said projectile. In continuing the operations, sufficient heat is
imparted to the mould by each projectile to prevent chilling of the next projectile
inserted. While the projectiles in this mould, I subject it to pressure by means of
hydraulic or other power. This pressure is maintained until the projectile is sufficiently
cooled and hardened, and the projectile is then removed from the mould.
I find it advantageous to use a inould having a central hole or recess into which the
point of the projectile will enter. I thus avoid liability to injury of the point in

page_text: the operation of placing the projectile in the mould. Moreover the said hole permits
the escape of any scale, dust or the like which may be introduced into the mould
with the projectilo or otherwise.
The mould must be of greater or less depth according to the length of the portion
of the projectile which it is desired to harden or temper. If the entire surfaco of the
projectile is to be hardened, the cavity in the mould should be of the same, or nearly
the same depth or length as the projectile.
In the accompanying drawing,
Figure 1 is a vertical central section of apparatus for holding a projectile while
subjected to pressure, and at the same time cooling it, a part of the hydraulic ram for
applying the pressure being shown in elevation.
Figure 2 is a similar view showing a modified form of the said apparatus.
The remaining figures are hereinafter referred to.
a is the mould, the projectile, e the hydraulic ram. The mould a is made with a
central hole a' for the purpose above specified, and its cavity is of such dimensions and
shape or configuration that the conical or conoidal end of the projectile will fit accurately
therein. A ring or annular piece d is placed upon the mould a and has fitted
therein taper segments e so formed that they will fit accurately within the said ring or
annular piece and closely around the cylindrical portion of the projectile. These
segments can be readily withdrawn from the ring or annular piece d to facilitate the
removal of the projectile from the mould a. A plug, mandrel or core-piece fis
inserted in the chamber or cavity of the projectile to prevent up-setting of its walls or
deformation of the said chamber or cavity. This mandrel receives pressure from the
ram and transmits it to the interior of the shell.
The apparatus shown in Figure 1 is designed for use when the entire mass of the
projectile is to be condensed and hardened.
If the conical, conoidal or ogival end only of the projectile is to be condensed and
hardened, I dispense with the said ring or annular piece and segments and also with
the said core-piece, and simply place a ring g of metal or other suitable material upon
the mould a to conduct away soine of the heat from the projectile and thus ensure a
gradual diminution of the hardness of the metal of the projectile at the top of the
mould a.
I prefer, moreover, to place a disc or pad h of asbestos or other suitablo
non-conductor or slow-conductor of heat between the base of the projectile and the
ram c, to prevent cooling of the said base by the ram.
By applying the pressure in the manner illustrated in Figures 1 and 2, the particles
or molecules are compelled to assume such a condition or arrangement that they will
offer the greatest resistance to end wise compression, and this result is effected without
inducing the state of tension which would be induced by cooling in liquids;
consequently the stress to which the projectile is subjected in the act of penetration is
a repetition of that to which it has already been subjected when in the mould.
In some instances, I employ a mould in which the projectile lies horizontally; this
mould is made in two parts or halves, in one of which the projectile. is to be laid and
the other of which is to be placed over the said projectile, and I apply pressure either
continuously or intermittently to the projectile, whilo in the said mould, in a direction
at right angles to its axis. Or I may form the mould of three, four or more segments
provided with means for adjusting them so as to apply the pressure equally all round
the projectile.
Figures 3 and 4 are sectional elevations showing different forms of apparatus in
which the projectile is to be placed horizontally. This apparatus comprises lower and
upper dies or moulds a, a². The lower die or mould a is supported upon a base-
platej formed with lugs or bearing pieces j'. The upper die or mould a² may be
firmly attached to the ram c. The base-plate is provided with a standard k through
which is passed a screw 1. In some instances a mandrel or plug f is inserted in the
cavity of the projectile or shell, as in Figure 3. In other instances the screw is
provided with a plug P, as in Figure 4, which fits into the cavity of the projectile or
shell. This screw prevents the displacement of the projectile from the mould when
subjected to the pressure of the ram. If the pressure is to be applied intermittently,

page_text: the said screw may be slackened from time to time and the projectile partially
rotated.
Whatever may be the construction of the mould, it should be made to conform to,
or fit the exterior of the projectile or a portion thereof, and the projectile, while in the
mould, should be kept under pressure so that there may be close contact between all
parts of the surface to be hardened and the mould, and the heat of the red hot mass of
metal may be conducted freely away through the body of the said mould.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I wish it understood that I
claim
First The above described method of hardening or tempering a projectile or shell
by heating the same and then cooling it while subjected to pressure, as, and for the
purposes, above specified.
Second An armour-piercing projectile hardened or teinpered under pressure without
the use of liquid, as above set forth.