AN IMPROVED MODE OF MANUFACTURING SHEET METAL
Year: 1857

page_text: LETTERS PATENT to Henry William Wimshurst, of St. John's Wood, in
the County of Middlesex, Gentleman, for the Invention of "AN
IMPROVED MODE OF MANUFACTURING SHEET METAL."
Scaled the 21st July 1857, and dated the 22nd January 1857.
PROVISIONAL SPECIFICATION left by the said Henry William Wimshurst
at the Office of the Commissioners of Patents, with his Petition, on
the 22nd January 1857.
I, HENRY WILLIAM WIMSHURST, of St. John's Wood, in the County of
Middlesex, Gentleman, do hereby declare the nature of the said Invention for
AN IMPROVED MODE OF MANUFACTURING SHEET METAL," to be as follows:-
The chief object of this Invention is to manufacture lead foil in a more
expeditious and economical manner than heretofore; but I also propose to
apply my improvements to the manufacture of sheet metal of various kinds,
using, however, only those metals or alloys which are fusible at a comparatively
low temperature. According to the ordinary mode of making lead foil, or lead
paper, as it is sometimes termed, cast pigs are subjected to rolling pressure
under several pairs of rolls, by which means the lead is ultimately reduced
from a thick block to the form of a thin tissue. By my improved process, the
lead while in a molten state is run from a height into a kind of die box, fitted
with lips, so adjusted that a free longitudinal space is preserved between them
for the exit of the metal. The pressure from above will cause the metal to

page_text: exude from between the lips in the form of a thin sheet, which sheet is then
conducted to adjacent pressing rolls, whereby it is reduced to the required
thickness.
The temperature of the metal as it descends from the reservoir is preserved
by the application of heat to the conducting pipe, and to prevent the too ready
flow of the metal from the die box a stream of cold water may be caused to
circulate through the exit side of the box, and thus chill the metal at or near
the point of exit; or the metal on leaving the die box in a molten state may
be received into a bath of oil, tallow, or other cooling medium, and then passed
to the rolls.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Henry William Wimshurst in the Great Seal Patent Office
on the 22nd July 1857.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
WILLIAM WIMSHURST, of Saint John's Wood, in the County of Middlesex,
Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-second day of January, in the year of our
Lord One thousand cight hundred and fifty-seven, in the twentieth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Henry William Wimshurst, Her special license that I, the said
Henry William Wimshurst, my executors, administrators, and assigns, or such
others as I, the said Henry William Wimshurst, my executors, administra
tors, and assigns, should at any time agree with, and no others, from time to
time and at all times thereafter during the term therein expressed, should
and lawfully might make, use, exercise, and vend, within the United Kingdom
of Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "AN IMPROVED MODE OF MANUFACTURING SHEET METAL," upon the
condition (amongst others) that I, the said Henry William Wimshurst, by
an instrument' in writing under my hand and seal, should particularly describe
and ascertain the nataire of the said Invention, and in what manner the
same was to be performed, and cause the same to be filed in the Great Seal
Patent Office within six calendar months next and immediately after the date
of the said Letters Patent...
NOW KNOW YE, that I, the said Henry William Wimshurst, do hereby
declare the nature of my said Invention; and in what manner the same is to

page_text: be performed, to be particularly described and ascertained in and by the
following statement, reference being had to the Drawing hereunto annexed,
and to the letters and figures marked thereon (that is to say) -
The chief object of this Invention is to manufacture lead foil in a more
expeditious and economical manner than heretofore; but I also propose to
apply my improvements to the manufacture of sheet metal of various kinds,
using, however, only those metals or alloys which are fusible at a comparatively
low temperature. According to the ordinary mode of making lead foil, or lead
paper, as it is sometimes termed, cast pigs are subjected to rolling pressure
under several pairs of rolls, by which means the lead is ultimately reduced from
a thick block to the form of a thin tissue. By my improved process the lead
while in a molten state is run from a height into a kind of die box, fitted with
lips, so adjusted, that a free longitudinal space is preserved between them for
the exit of the metal.
The pressure from above will cause the metal to exude from between the
lips in the form of a thin sheet, which sheet is then conducted to adjacent
pressing rolls, whereby it is reduced to the required thickness. The temperature
of the metal as it descends from the reservoir is preserved by the application
of heat to the conducting pipe, and to prevent the too ready flow of the metal
from the die box a stream of cold water may be caused to circulate through the
exit side of the box, and thus chill the metal at or near the point of exit; or
the metal on leaving the die box in a molten state may be received into a bath
of oil, tallow, or other cooling medium, and then passed to the rolls.
Fig. 1 in the accompanying Drawing is a vertical section of the apparatus,
and Fig. 2 is a partial front clevation; some of the parts being removed to
shew more clearly those behind.
The apparatus is composed of two hollow metal castings or vessels, A and C,
for containing the molten lead. The vessels A and C are connected together
by means of a vertical metal pipe or tube B, of about two inches in diameter,
and of any convenient length, not less than twelve or fourteen feet. The upper
vessel or casting A, which may be called the receiver, is from two to three feet
in diameter, by about eighteen inches deep, and is surrounded on all sides by a
grate or fire-place, in which is kept coke or wood in a state of combustion. In
this vessel or receiver, which may be made of large dimensions if desired, the
metal intended to be operated upon is melted, and is then conducted down the
vertical tube B to the lower vessel or drawing box C, which is shewn detached
in horizontal section at Fig. 3. The tube B is intended to be of such a height
that the weight of molten metal contained therein will force out the metal from
the longitudinal slit or opening a, a, of the lower vessel C, with a pressure

page_text: equal to from seventy to eighty pounds on every square inch of surface of the
opening. I would here mention, that the metal contained in and passing
through the tube B is kept in a state of fusion by means of the flue b, which
surrounds it, and conducts the heated vapours and gaseous products of com-
bustion from the fire-place d, under and at the back of the lower box C. which
is thereby kept at a certain and regular heat, and is provided with an adjusting
damper to regulate the draught. The heated gases, after passing up the flue b,
round the vertical pipe B, and heating the same, are made to act on the under
The box or vessel C
side of the upper vessel or chamber A, as seen in Fig. 1.
is made of cast iron, and is several inches in thickness, and is provided with a
projection or lip, about six or eight inches in breadth, running the whole
length of the box or vessel C. The upper side of this lip is planed, and brought
to a perfectly smooth surface, and is parallel with the longitudinal slit or
opening a of the vessel C. Pieces of steel h, h, Fig. 2, (the thickness of the
sheet intended to be formed) are then laid at each end of this lip, one of their
ends coming in contact with the front of the box C; another lip or block of
ironi, corresponding in size with the lip, and with its lower side brought to a
smooth surface, is placed upon these two slips of steel, and tightly pressed down
on to them and against the front of the box by means of screws s. It will be
seen, that a parallel aperture is thus formed of nearly the breadth of the lip,
through which a continuous stream of the fluid metal would readily flow when
pressed by the weight of the superincumbent metal in the tube B. In order to
convert this stream into a thin sheet, it is intended first to solidify the metal
in its passage between the lips and i, by keeping them at a temperature
somewhat below the fusing point of the metal operated upon, and passing the
sheet of solid metal between one or more pairs of rollers j, j. The cooling of
the lips and i is effected by making them hollow, and causing cold water to
flow through them by means of a hole k, or series of holes bored in a hori
zontal direction through the entire length of the two lips. Water is supplied
to the hollow parts of the upper lip i through a pipe 7, and after passing through
the upper lip i, the water flows through the bent pipe m into the hollow parts
of the lower lip, and ultimately it passes down a pipe n, and away out of the
apparatus. By this means a stream of water is kept constantly passing through
the lips at a regular rate, and will maintain the latter at an uniformn tem-
perature. The pressure from within the box or vessel C must be sufficient to
force the congealed metal through the lips, and as the metal contracts as it
solidifies this will be comparatively an easy matter. Upon issuing from between
the lips the solid sheet is deposited on a stationary plate or table p, from whence
it passes between the two rollers j, j, whereby it is reduced and flatted ready

page_text: It will be obvious that two or more pairs of rollers may be used if
required, but I have not thought it necessary to shew them in the Drawing. I
would remark, that in some cases, where it would be either inconvenient or
impracticable to obtain suflicient height to give the requisite pressure to the
mass of metal in the vessel C, additional pressure may be obtained by means
of a weighted piston or follower made to work either in the vessel A, or directly
upon the mass in the vessel C, which must, however, under such circumstances,
be modified in form to suit the case.
Having now described my improved mode of manufacturing sheet metal,
and the manner of carrying the same into effect, I would observe, that although
I have described the arrangement of apparatus which I prefer to use for the
purposes of my Invention, I do not mean or intend to confine myself rigidly to
the precise arrangement or construction of parts herein shewn and described,
as they may, perhaps, be varied without departing from the nature and object
of my Invention, and I do not claim the forcing semi-molten, molten, or solid
soft metal through a die or dies for the purpose of converting the same into
various forms; but that which I consider to be new in the above-described
mode of manufacturing sheet metal, and therefore desire to claim as the
Invention secured to me by Letters Patent, as aforesaid, is, causing the soft
metal by the pressure of the superincumbent mass to exude in the form of a
sheet from a properly formed or constructed aperture made in the vessel below,
which sheet may be conducted between rollers to be reduced to the requisite
thickness, as above described.
In witness whereof, I, the said Henry William Wimshurst, have here-
unto set my hand and seal, the Twenty-second day of July, in the
year of our Lord One thousand eight hundred and fifty seven.
Witness,
FRED. WALKDEN,
66, Chancery Lane.
H. W. WIMSHURST. (L.S.)