IMPROVEMENTS IN THE MANUFACTURE OF TIN PLATE AND BLACK PLATE, AND IN THE MACHINERY, APPARATUS, AND PROCESSES EMPLOYED IN SUCH MANUFACTURE
Year: 1879

page_text: LETTERS PATENT to Henry Bessemer, of Denmark Hill, in the County of
Surrey, Civil Engineer, and Alfred George Bessemer, of Oakfield, South
Dulwich, in the same County, for the Invention of "IMPROVEMENTS IN THE
MANUFACTURE OF TIN PLATE AND BLACK PLATE, AND IN THE MACHINERY,
APPARATUS, AND PROCESSES EMPLOYED IN SUCH MANUFACTURE."
Sealed the 1st July 1879, and dated the 5th April 1879.
PROVISIONAL SPECIFICATION left by the said Henry Bessemer and Alfred
George Bessemer at the Office of the Commissioners of Patents on the 5th
April 1879.
HENRY BESSEMER, of Denmark Hill, in the County of Surrey, Civil Engineer,
and ALFRED GEORGE BESSEMER, of Oakfield, South Dulwich, in the same County.
"IMPROVEMENTS IN THE MANUFACTURE OF TIN PLATE AND BLACK PLATE, AND
IN THE MACHINERY, APPARATUS, AND PROCESSES EMPLOYED IN SUCH MANU-
FACTURE."
Our improvements in the manufacture of tin plate, and what is known in the
trade as black plate, which is tin plate in its earlier stago, consist, firstly, of certain
modes of preparing the thick bars called "tin plate bar" previous to their being
heated for rolling into thin plates, and also in the modes of heating the same so as
to prevent or lessen surface oxidation during the heating process, and in certain
methods of detaching the scale if such should be formed immediately prior to or
during the rolling of such plates, and also in the machinery employed, and in the
mode of rolling the plates from a thick bar into sheets of the desired degree of
thinness, or nearly so, at a single operation; also, in the modes of cutting the same
into lengths during the rolling operation, and in preventing or arresting the forma-
tion of scale by exposure of the hot rolled plates to atmospheric influences after they
have been rolled.
It has been found that homogeneous malleable iron or mild steel, which has be
formed in a fluid state into ingots, has all the parts of the mass so uniformly
coherent that both in a cold and in a heated state such metal will bear an amount
of fatigue, distortion, or sudden extension of its surface as could not safely be
applied to iron or steel that has been puddled or piled. Hence homogeneous malle-
able iron or mild steel approaching iron in quality when employed for the production
of tin or black plates, may be subjected to more violent action than could be
practiced successfully with wrought iron that has been made in the usual way. For
1071

page_text: the purposes of our Invention, we therefore prefer to employ homogeneous malleable
iron or mild steel made by the Bessemer process of conversion, or by other means
capable of producing metal of a similar character, and which metal, for the purposes
of our Invention, may be rolled into long slabs or bars in the ordinary way or by
any improved means, and we prefer to make such bars of the breadth, or nearly of
the breadth, of the tin plates to be made therefrom, and of a thickness by preference
varying from $/, of an inch to 3/4 of an inch; such long rolled bars may be cut
into lengths varying from 3 to 6 feet, more or less. For this purpose we employ a
hydraulic shearing machine, consisting of a fixed upper jaw, and a moveable lower
jaw firmly attached to a rising and falling ram fitted into a water cylinder and
properly guided in its frame; both the upper and under jaws are so formed with
inclined or curved surfaces as not only to cut the bar in pieces of the desired length,
but at the same time to squeeze and thin out or taper the end of the bar so cut,
for the purpose of facilitating its entrance between the rolls; the bar, while being
cut, is retained in a guide, so as to present its axis at right angles to the cutter of
the shearing machine.
The tin plate bar having been cut into the desired lengths (preferably while hot)
may be cleansed by pickling in dilutė sulphuric or hydrocloric acid; the bar, having
been thus freed from adhering scale, may then be passed cold through a pair of
smooth plain rolls one or more times, in order to render its surface very smooth and
even prior to reheating the same; or in lieu of this cold rolling the surface of the
bars may have a very smooth or bright surface given to them by grinding their
surfaces and edges by means of grindstones or emery wheels, whereby the surface
of the thin plates produced therefrom are much improved. The tin plate bar is
then ready for the heating and rolling processes, and in order to preserve the smooth
and even surface of the bars, and prevent scaling during the heating process, we
employ furnaces in which retorts are set in a manner similar to that employed in
setting the retorts employed in the manufacture of coal gas, and which retorts may
be formed of fire-clay or of metal, but as metal retorts conduct heat much more
rapidly than clay, and as a very high temperature is required, we prefer in lieu of
using cast iron for this purpose to make them of homogeneous malleablo iron or
steel, by casting or founding such metal into the desired form, and with or without
shelves, partitions, grooves, or projections in the interior thereof, for the separation
of the plates as may be desired. When plates are piled upon each other flat wise
in such retorts, we prefer to protect the contiguous surfaces with a little lime or
other matter in a state of fine powder, for the purpose of preventing adhesion at
very high temperatures; and we also put into such retorts small lumps of coal or
other substance capable of producing an artificial atmosphere in such retorts less
capable of oxidizing the plates than pure atmospheric air. The ends of the retorts
are moveable for the purpose of inserting the pieces of bar, and for the removal
thereof, and in some cases where the retort furnaces cannot be placed near the
rolling mill, we use moveable metal retorts or boxes for heating the tin plate bar,
and which moveable retorts or boxes may be removed from the heating furnace and
brought with the bars in them to the rolls. For the cheaper or inferior qualities
the bars may be heated in a reverberatory or other suitable open furnace, in which
case as little free oxygen as possible should be allowed to enter the furnace, but in
any case bars so heated will have a scale of oxide formed upon them. We therefore
pass the bars between several small rolls arranged after the manner of "plate bending
rolls," whereby the bars passed through them will be bent once or more in opposite
directions, for the purpose of detaching the scale from their surfaces, the detached
portion of scale being blown away by jets of air or steam. Such rolls may be fitted
in a separate frame, but we prefer to fix them in immediate connection with the
main rolls, so that the operation of scaling the bar and rolling down to thin plate
may go on simultaneously..
The rolling mill which we employ for the production of thin plates from the bars
so heated consists of two main frames or housings, between which the main rolls
revolve, and which frames may be united by bolts and flanges at the top and

page_text: bottom thereof, or in such way as to prevent the great force employed from causing
any deviation in the true parallelism of the rolls. For the purposes of our
Invention it is necessary that the rolls should be much larger in diameter than is
required when rolling tin plates by passing them several times through the rolls,
at each of which passes the plate or packet of plates is slightly reduced in thickness
by altering the relative distance apart of the rolls. It is also desirable that the
rolls should be driven at a much greater surface speed than is necessary when
rolling tin plates in the ordinary way in order to allow the necessary heat to be
maintained until the long piece of tin plate bar is formed into a sheet of great
length, or into a greater number of shorter lengths of black plate. The main rolls
run in brasses capable of accurate adjustment crosswise, so as to secure their true
parallelism; the top roll is pressed upwards against its brasses by a lever, or
preferably by a pair of hydraulic cylinders, so as always to run free of the lower
roll; screws are employed to regulate the thickness of the metal passing between
them, and divided discs are mounted on these screws to show how much they are
moved, when an adjustment of them is necessary. The great speed that it is
desirable to drive the rolls and the friction of their axes under heavy pressure
renders it necessary that special precautions should be taken to prevent the over-
heating of the roll journals; for this purpose we carry water from an elevated
reservoir in a pipe to the rolling mill; the main pipe is provided with a cock, by
means of which the water may be turned on or off when required; small branch
pipes proceed from this main to each of the journals of the main rolls, and are con-
nected with the brasses in which they revolve, so that a film of walter may escape
under pressure between the brasses and the journal as the latter revolves, and thus
cool these surfaces effectually. In some cases jets of water from this main pipe
may be projected in the form of spray upon the bar while being rolled to assist in
detaching scale, or upon the thin sheet as it emerges from the rolls for the purpose
of cooling it and preventing the formation of scale. Brackets are formed on the
housings, to which a ribbed guide plate is attached, this guide plate has raised sides,
between which the length of tin plate bar is guided during its passage through the
rolls. Above and below this guide plate is a small roll driven by wheels on the
main rolls or on the shafts by which they are driven, the space between the smaller
rolls is such that the tiu plate bar can be freely pushed along the guides in between
them, its taper end going forward as far as the large rolls will permit. The lower
small roll is then suddenly forced upward, so as to bite the bar between it and the
upper small roll; by this means the tin plate bar will be carried forward with
considerable force, presenting its tapered end into the small taper space left between
the main rolls, which will so press upon it as to draw it between them. The space
between the main rolls is so small that the sheet emerging therefrom will be thin
enough or nearly thin enough to constitute the black plate required at a single
rolling operation; the small rolls employed to force the taper end of the bar into
the narrow wedged shape space between the main rolls may be driven by a carrier
or ratchet wheel, so that when the main rolls seize the bar the small rolls may not
unduly force it forward or offer any obstruction to the passage of the bar through
the main rolls; the moment the workmen observes that the bar is being taken
forward by the main rolls he will release the grip of the small rolls upon it. The
small rolls or feeding rolls, as they may be called, we prefer to grip the bar by
bydraulic pressure derived from an accumulator in a manner well understood, there
being a small hydraulic ram and cylinder under each brass of the lower roll, so that
the workman by means of a lever acting on a suitable valve may rapidly put on or
take off the grip of the feeding rolls. It will be thus understood that if the main
rolls are adjusted to a distance of one fiftieth of an inch apart, and further, that
the tin plate bar is half an inch in thickness, that the issuing thin plate will be
nearly twenty five times as long as the bar, and will produce about one hundred
and fifty feet of black plate from a six foot length of bar at a single operation; and
further, if the main rolls slightly exceed thirty inches in diameter, or are equal to
eight feed in circumference, that about twenty revolutions only of the main rolls

page_text: will be required to pass a bar six feet long through them, and by giving a speed of
say forty revolutions per minute to such rolls the time occupied in passing the bar
through the rolls will be about half a minute, a speed which will cause such a
developement of heat in the parts under pressure as greatly to facilitate the rolling
operation. We however desire it to be understood that the size of the rolls, their
speed of rotation, and the thickness of the bar employed, are only given approxi-
mately for the purpose of rendering the rolling process better understood, and may
be modified as may be found desirable in practice. The thin sheet of metal as it
rapidly emerges from between the rolls in a heated state may in some cases be
made to pass between another pair of rolls, preferably of much less diameter than
the main rolls, and may here undergo a further reduction in thickness, care being
taken to speed those rolls so as to work properly in conjunction with the main
rolls; or in lieu of this mode of operating we prefer to allow the thin sheet as
it emerges from the main rolls to pass between guide plates which will conduct it
into the jaws of a pair of vertically acting shears operated on by a cam, so as to
make a very rapid movement through a very small distance, and thus cut off the
issuing sheet into such lengths as may be desired, and which will be regulated by
the relative velocity of the cam shaft and the main rolls; or in lieu of the recipro-
cating shears a revolving bar or cutter shod at each end with an adjustable cutter
may be made to shear the metal into the lengths desired; in either case we place
below, the shearing apparatus a tank partly filled with water, oil, or other fluid, into
which the plates as sheared off may fall, and thus prevent that oxidation of the
surface which slowly cooling in the air would produce; if water acidulated with
sulphuric or hydrochloric acid be employed the plate will be effectually cleaned of
any external film of oxide.
In some cases it may be preferred to retain the long sheet of thin metal in a
continuous piece, in which case we provide a revolving drum having a notch or
opening on one side, the drum having its axes parallel to the axes of the main rolls,
and so placed near the end of the guide plates that the sheet of thin metal may be
directed into the notch before named, where, pushing against a catch, it will be
locked fast to the drum, and at the same time throw the axis of the drum into
gear with a revolving shaft, so that the thin sheet of metal may be wound up on
the drum as fast as it is produced, the drum being replaced by an empty one for
the next rolling operation.
If it be desired to make the edges of the thin plates more perfect than they are
produced by the rolling operation we use a pair of revolving shears between the
main rolls and that part of the apparatus where the thin sheet is cut into lengths,
or wound on a drum, or is otherwise disposed of; these shearing rolls consist of a
plain roll of an exact length corresponding with the intended breadth of the plate,
and a second roll of the same length on which two circular dises are mounted,
forming a sort of raised flange at each end with sharp chisel like cutting angles,
which will cut off the uneven edges and render the sheet of metal even and parallel
throughout its length, by which arrangements or some of them the length of tin
plate bar when put into the rolling machine will be converted without labor or
reheating in the furnace into a great number of thin plates sheared to the desired
length and breadth and delivered into the pickling tank almost free from external
scale, and in a very short period of time. The plates when cooled down in the
tank, either with or without being annealed, may be wiped dry and be flattened
and smoothed only, or they may be further extended if desired by cold rolling
between polished cast steel rolls or highly polished chilled rolls set to a definite
distance apart by screws, or as we prefer when used only for improving the surface
of the plate, forced together by hydraulic cylinders actuated by an accumulator of
small size under spring pressure, the cold rolling apparatus having a table at each
side, the surface of which is at a tangent with the upper surface of the bottom roll,
and will admit of the rapid passage of plates between them.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Henry Bessemer and Alfred George Bessemer in the Great Seal Patent
Office on the 4th October 1879.
HENRY BESSEMER, of Denmark Hill, in the County of Surrey, Civil Engineer,
and ALFRED GEORGE BESSEMER, of Oakfield, South Dulwich, in the same County.
"IMPROVEMENTS IN THE MANUFACTURE OF TIN PLATE AND BLACK PLATE, AND
IN THE MACHINERY, APPARATUS, AND PROCESSES EMPLOYED IN SUCH MANU-
FACTURE."
Our improvements in the manufacture of tin plate and what is known in the
trade as black plate, which is tin plate in its earlier stage, consist firstly of certain
modes of preparing the thick bars called "tin plate bar" previous to their being
heated for rolling into thin plates, and also in the modes of heating the same, so as
to prevent or lessen surface oxidation during the heating process, and in certain
methods of detaching the scale if such should be formed immediately prior to or
during the rolling of such plates, and also in the machinery employed, and in the
mode of rolling the plates from a thick bar into sheets of the desired degree of
thinness or nearly so at a single operation; also in the modes of cutting the same
into lengths during the rolling operation, and in preventing or arresting the
formation of scale by exposure of the hot rolled plates to atmospheric influences
after they have been rolled.
It has been found that homogeneous malleable iron or mild steel which has been
formed in a fluid state into ingots has all the parts of the mass so uniformly coherent
that both in a cold and in a heated state such metal will bear an amount of fatigue,
distortion, or sudden extension of its surface as could not safely be applied to iron
or steel that has been puddled or piled.
Hence homogeneous malleable iron or mild steel approaching iron in quality
when employed for the production of tin or black plates may be subjected to more
violent action than could be practiced successfully with wrought iron that has been
made in the usual way. For the purposes of our Invention we therefore prefer to
employ homogeneous malleable iron or mild steel made by the Bessemer process of
conversion, or by other means capable of producing metal of a similar character,
and which metal, for the purposes of our Invention, may be rolled into long slabs
or bars in the ordinary way or by any improved means; and we prefer to make
such bars of the breadth or nearly of the breadth of the tin plates to be made
therefrom, and of a thickness by preference varying from 3, of an inch to 3/4 of an
inch. Such long rolled bars should have clean and neatly formed edges, and a good
clear or smooth surface, such as is obtained by the employment of grooved rolls as
practised in the manufacture of ordinary merchant bars. While still hot from the
rolling process such bars may be cut into lengths varying from 3 to 6 feet, more or
less; for this purpose we employ a hydraulic shearing machine consisting of a fixed
upper jaw and a moveable lower jaw firmly attached to a rising and falling ram
fitted into a water cylinder and properly guided in its frame; both the upper and
under jaws are so formed with inclined or curved surfaces as not only to cut the
bar in pieces of the desired length, but at the same time to squeeze and thin out or
taper the end of the bar so cut for the purpose of facilitating its entrance between
the rolls. The bar while being cut is retained in a guide so as to present its axis
at right angles to the cutter of the shearing machine.
And in order that the mode of constructing and operating such shearing appa-
ratus may be fully understood we have represented the same on Sheet A of the
annexed Drawings, where Figure 1 is a front elevation; Figure 2, a vertical section
on the line A, B, of Figure 1; and Figure 3, a sectional plan on the line C, D, of
Figure 1, where the ram c and the sliding plate i are omitted.
In these Figures a
reprosents a massive bed plate in which the hydraulic cylinder b is supported by its
upper flauge b'; this cylinder we prefer to cast in mild steel and to bore out truly,

page_text: so as to accurately fit the ram c; a flanged collar d serves to confine the hydraulic
leather in place, and at the same time to prevent the scales falling from the sheared
metal entering the space between the ram and its cylinder. An inverted flanged
ring e fitted on to the ram overhanges the vertical part of the ring d and thus
effectually prevent the falling scale from entering between the ram and its
cylinder.
Two massive castings f, f, are bolted by their lower flanges to the bed plate a,
each having a pair of large steel bolts g passing up through them for the purpose
of securing the cross head h of the apparatus firmly in place. The lower ends of
the bolts g passing through the bed plate a and the crossheadh thus uniting the
upper and lower parts of the framing firmly together. The inner faces of the
castings ff, are truly planed, and a recess or groove is formed in which a massive
plate may slide up and down; this groove is best seen at y in Figure 3. In order
to insure the precision of this motion the grooves before referred to are made
sufficiently wide to allow a bar of steel k to be fitted within the groove, and there
held by bolts k¹ having slotted holes. There are also screws m passing through the
casting and pressing the bark against the sliding plate i, and thus tighten it up
as it wears and keep it steadily in place. The lower end of the slide i rests on the
ram c and rises and falls with it, and the upper part of it has a shoulder on which
rest two hardened and tempered pieces of steel n and p; the piece n forms the
shearing part or lower jaw of the shears, and the piece p the pressing part used for
tapering the end of the sheared bar; these pieces of steel are secured to the slide i
by bolts, as shewn.
8.
The crossheadh has a groove formed on its underside from end to end, and into
this groove the upper end of the castings f, f, are fitted; the groove also serves to
retain in place a piece of steel g, on the lower side of which is fitted the shearing
and pressing blade r, secured thereto by bolts as shewn. The position of the
cutting edge of the blade r may be adjusted by the removal or addition of thin
packing pieces in the dovetailed side at q*, against which it is forced by the screws
To prevent too great a movement of the slide i in an upward direction, steel
pieces t, t, are fitted to the crosshead h, which come in contact with the slide i,
whenever the desired amount of tapering is given to the end of the bar, the
position of the lower and upper jaw of the shearing apparatus at the time when
the operation is completed, is shewn on a larger scale at Figure 4, where u shews a
portion of the bar with its tapered end still held between the pressing pieces p and
r, while in Figure 2, the bar u is shewn in the position it would occupy at the
moment when the upper and lower cutting edges first come in contact with it. The
guides for conducting the bar with its axis at right angles to the face of the cutters
is omitted in the Drawings to allow other parts to be more clearly seen, it consists
simply of a plate or frame with raised sides, forming a sort of trough in which the
end of the plate lies when being fed into the apparatus. In some cases it may be
found desirable to place the shearing apparatus in a pit or sunk space, so that the
jaws of the shears shall be level with the floor of the rolling mill, thus allowing the
bar to be pushed into or between the jaws without lifting it from the floor.
In working this apparatus, we prefer to employ an accumulator and force pumps,
such as are in common use for working the hydraulic apparatus connected with the
Bessemer process of making steel, but we prefer to use a higher pressure than is
generally employed for that purpose; various arrangements of equilibrium valves or
piston valves may be employed for the purpose of admitting water under pressure
from the accumulator to the hydraulic cylinder b of this shearing apparatus. Such
a valve should be employed for this purpose as will allow the operator without
exerting much force to open a passage for the ingress and egress of water sufficiently
large to produce a quick motion of the ram in either direction, and thus limit the
time during which the cutting and pressing surfaces are in contact with the heated
bar.
The tin plate bar having been cut into the desired lengths (preferably while hot),
may be cleansed by pickling in dilute sulphuric or hydrochloric acid; the bar

page_text: having been thus freed from adhering scale may then be passed cold through a pair
of smooth plain rolls one or more times, in order to render its surface very smooth
and oven prior to reheating the same; or in lieu of this cold rolling, or after such
cold rolling process has been performed, the surface of the bars may have a very
smooth or bright surface given to them by grinding their surfaces and edges by
means of grindstones or emery wheels, whereby the surface of the thin plates
produced therefrom are much improved. The tin plate bar is then ready.for the
heating and rolling processes; and in order to preserve the smooth and even surface of
the bars, and prevent scaling during the heating process, we employ furnaces in
which retorts are set in a manner similar to that employed in setting the retorts
employed in the manufacture of coal gas, and which retorts may be formed of fire
clay or of metal, but as metal retorts conduct heat much more rapidly than clay,
and as a very high temperature is required, we prefer in lieu of using cast iron for
this purpose to make them of homogeneous malleable iron or steel, by casting or
founding such metal into the desired form, and with or without shelves, partitions,
grooves, or projections in the interior thereof, for the separation of the plates as
may be desired. When plates are piled upon each other flat wise in such retorts,
we prefer to protect the contiguous surfaces with a little lime or other matter in a
state of fine powder, for the purpose of preventing adhesion at very high tempera-
tures, and we also put into such retorts small lumps of coal or other substance
capable of producing an artificial atmosphere in such retorts, less capable of
oxidizing the plates than pure atmospheric air; the ends of the retorts are moveable
for the purpose of inserting the pieces of bar and for the removal thereof, and in
some cases where the retort furnaces cannot be placed near the rolling mill, we use
moveable metal retorts or boxes for heating the tin plate bar, and which moveable
retorts or boxes may be removed from the heating furnace, and brought with the
bars in them to the rolls.
The form and arrangements of the retort furnaces employed for heating the tin
plate bars may be considerably varied, depending partly on the available space in
the works and on the kind of fuel to be employed, but we prefer to place the retorts
in a line all on the same level in preference to placing them one above the other, the
height above the floor being such that the workman can most conveniently with-
draw the bars from them by means of a pair of tongs suspended by a light rod or
chain from an overhead slide or rail; we also prefer to place the rolling mill at such
a height that the space between the rolls shall be about the same distance from the
floor as the centre of the retorts
The form of retort or heating chamber which we prefer is shewn in cross section
at Figure 5, Sheet A, and in longitudinal vertical section at Figure 6. If the interior
dimensions of such a retort are 13 inches in height by 18 inches in width and about
7 feet in length, it will allow 30 bars to be placed within it in an inclined position,
as shown in Figure 5, provided these bars do not exceed 12 inches wide by an
inch in thickness and 6 feet in length, in which case each bar would weigh fully
1 cwt. Now the workman can roll off one of these bars on an average every 2
minutes, thus each retort will supply the mill for 1 hour, and during that time it
will produce 30 cwt. of thin plates, hence as the bars require from 6 to 7 hours to
heat them up to the proper pitch for rolling, a furnace with 8 retorts of the size
indicated will keep up a continuous supply of heated bars for such a mill. We
desire it to be understood that the times and weights herein mentioned may be
subject to considerable variations from various causes, and are only given in order
to indicate more clearly the general results of working on the principle embraced in
our Invention. At Figure 6 we have shewn one end of the retorts A resting on a
brick corbel at the back of the furnace; the opposite end of the retort enters the
front wall, but does not pass through it, as much heat would in that case be con-
ducted away, and we prefer to form this end of the retort with an inclined surface,
so that a fire tile or plate B may rest and be luted close up against it, and thus
confine the heat as much as possible during the time the bars are being heated; we
also fix an iron frame C against the furnace wall, having a horizontal sliding plate

page_text: D closely fitted to it, and which can be easily pulled aside and closed again as the
bars are withdrawn. It will be understood that the tile or plate D is only used
prior to the withdrawal of the bars.
Small lumps of coal or other substance capable of producing a non-oxidizing
atmosphere are put into the retort, as shewn at E. If desired, the bars may be
placed upon each other, as shewn at Figure 7, which is a cross section of another
form of retort suitable for that purpose. The importance of preventing any scaling
of the bar will be apparent when it is considered how such scales would become
embedded into and injure the surface of a thin plate when such plate is produced by
a single passage through the rolls.
For the cheaper or inferior qualities the bars may be heated in a reverberatory or
other suitable open furnace, in which case as little free oxygen as possible should be
allowed to enter the furnace, but in any case bars so heated will have a scale of
oxide formed upon them; we therefore pass the bars between several small rolls
arranged after the manner of "plate bending rolls," whereby the bars passed
through them will be bent once or more in opposite directions for the purpose of
detaching the scale from their surfaces, the detached portion of scale being blown
away by jets of air or steam; such rolls may be fitted in a separate frame, but we
prefer to fix them in immediate connection with the main rolls, so that the operation
of scaling the bar and rolling down to thin plate may go on simultaneously.
For this purpose we prefer to place three rolls in the same horizontal plane and
parallel with each other, and only an inch or two apart, and above these rolls we
place two other rolls, also parallel to each other and to the rolls beneath them;
one of these upper rolls occupying a position vertically over one of the lower ones,
while the other upper roll is placed vertically over the space left between the other
two lower ones. The upper rolls are made to approach the lower ones so nearly
that a bar cannot be passed between the series of rolls without being bent first in
one direction and then in an opposite one, which will have the effect of throwing
off any scale formed on their surfaces in the heating furnace.
The mode of mounting and driving bending rolls for bending iron plates is well
understood, and admits of considerable variation in the details without affecting
the general principle on which its efficiency depends. We therefore do not confine
ourselves to any precise details of construction in such bending apparatus.
The rolling mill which we employ for the production of thiu plates consists of
two main frames or housings between which the main rolls revolve, and which
frames may be united by bolts and flanges at the top and bottom thereof, or in
such way as to prevent the great force employed from causing any deviation in the
true parallelism of the rolls. For the purposes of our Invention it is necessary or
desirable that the rolls should be much larger in diameter than is required when
rolling tin plates by passing them several times through the rolls, at each of which
passes the plate or packet of plates is slightly reduced in thickness by altering the
relative distance apart of the rolls. It is also desirable that the rolls should be
driven at a much greater surface speed than is necessary when rolling tin plates in
the ordinary way, in order to allow the necessary heat to be maintained until the
long piece of tin plate bar is formed into a sheet of great length or into a great
number of shorter lengths of black plate. The main rolls run in brasses capable of
accurate adjustment crosswise so as to secure their true parallelism, the top roll is
pressed upwards against its brasses by a lever, or preferably by a pair of hydraulic
cylinders, so as always to run free of the lower roll; screws are employed to
regulate the thickness of the metal passing between them, and divided discs are
mounted on these screws to show how much they are moved when an adjustment
of them is necessary.
The great speed that it is desirable to drive the rolls aud
the friction of their axes under heavy pressure renders it necessary that special
precautions should be taken to prevent the over heating of the roll journals; for
this purpose we carry water from an elevated reservoir in a pipe to the rolling mill,
the main pipe is provided with a cock by means of which the water may be turned
on or off when required; small branch pipes proceed from this main to each of the

page_text: journals of the main rolls, and are connected with the brasses in which they revolve,
so that a film of water may escape under pressure between the brasses and the
journal as the latter revolves and thus cool these surfaces.effectually; in some cases
jets of water from this main pipe may be projected in the form of spray upon the
bar while being rolled to assist in detaching scale, or upon the thin sheet as it
emerges from the rolls, for the purpose of cooling it and preventing the formation
of scale. Brackets are formed on the housings to which a ribbed guide plate is
attached; this guide plate has raised sides between which the length of tin plate
bar is guided during its passage through the rolls. Above and below this guide
plate is a small roll driven by wheels on the main rolls or on the shafts by which
they are driven, the space between the smaller rolls is such that the tin plate bar
can be freely pushed along the guides in between them, its taper end going forward
as far as the large rolls will permit. The lower small roll is then suddenly forced
upward so as to bite the bar between it and the upper small roll; by this means the
tin plate bar will be carried forward with considerable force, presenting its tapered
end into the small taper space left between the main rolls, which will so press upon
it as to draw it in between them.
The space between the main rolls is so small that the sheet emerging therefrom
will be thin enough or nearly thin enough to constitute the black plate required at
a single rolling operation. The small rolls employed to force the taper end of the
bar into the narrow wedged shape space between the main rolls may be driven by
a carrier or ratchet wheel, so that when the main rolls seize the bar the small rolls
may not unduly force it forward or offer any obstruction to the passage of the bar
through the main rolls; the moment the workman observes that the bar is being
taken forward by the main rolls he will release the grip of the small rolls upon it;
we prefer that the small rolls (or feeding rolls as they may be called) should grip
the bar by means of hydraulic pressure derived from an accumulator in a manner
well understood, there being a small hydraulic ram and cylinder under each brass
of the lower feeding roll, so that the workman by means of a lever acting on a
suitable valve may rapidly put on or take off the grip of the feeding rolls. It will
be thus understood that if the main rolls are adjusted to a distance of one fiftieth of
an inch apart, and, further, that the tin plate bar is half an inch in thickness, that
the issuing thin plate will be nearly twenty five times as long as the bar, and will
produce about one hundred and fifty feet of black plate from a six foot length of bar
at a single operation; and, further, if the main rolls slightly exceed thirty inches in
diameter, or are equal to eight feet in circumference, that about twenty revolutions
of the main rolls will be required to pass a bar six feet long through them, and by
giving a speed of, say, forty revolutions per minute to such rolls the time occupied
in passing the bar through the rolls will be about half a minute, a speed which will
cause such a developement of heat in the parts under pressure as greatly to facili-
tate the rolling operation; we however desire it to be understood that the size of
the rolls, their speed of rotation, and the thickness of the bar employed, are only
given approximately for the purpose of rendering the rolling process better under-
stood, and may be modified as may be found desirable in practice, but we never-
theless desire it to be understood that the amount of heat developed by the rapid
application of great mechanical force plays an important part in our new system of
rolling tin and black plates, for it is well known that the facility with which the
flow or extension of iron under a given pressure takes place depends greatly on its
temperature, hence we see in the rolling of tin plate, as heretofore generally
O practiced, by repeatedly passing the metal between the rolls, that the loss of heat
both by radiation and by conduction into the rolls is in proportion to the gradually
increasing surfaces and the time which those surfaces are exposed to radiation,
hence gradual and progressive rolling becomes a cooling operation, greatly increasing
the amount of mechanical force necessary to extend the plate, the rolling operation
5 taking place under conditions most unfavorable to the extension of the plate,
while the amount of mechanical force absorbed by the friction of the roll journals
by these repeated operations is in proportion to the spaces passed through by their

page_text: surfaces, and the amount of pressure required to compress and extend the com-
paratively hard and cool surfaces of the metal passed through them, at the same
time this cooling of the metal during the rolling process renders it necessary to heat
the metal in the furnace again and again before the tin plate bar is reduced to
plates of the desired degree of thickness.
Now in our new process of rolling tin and black plate we avoid much loss of heat
by radiation by retaining every portion of the heated bar in its original massive
form until the instant when each portion of it is required to undergo a sudden
transformation from a thick bar to a very thin plate, the extreme rapidity of this
change of form, and the force expended in thus suddenly altering the relative position
which the molecules of the mass occupy with reference to each other developes a
great amount of heat at the part where this change of form is effected; thus our
system of rolling is a heating and not a cooling process, and the softening of the
metal by this conversion of force into heat greatly facilitates the flow of the metal,
and lessens the amount of strain on the rolls, which would otherwise be very great,
at the same time the amount of mechanical power absorbed by the friction of the
roll axles is reduced in proportion to the spaces passed through by their surfaces in
producing a given quantity of plate, and the temperature and relative softness of
the metal where the flow takes place.
It will be obvious that a mill so operating will produce a much greater quantity
of plate in a given time, and with much less manual labour, and with a less number
of heating furnaces than would be required in the present system of alternate
rolling and reheating, while the loss of metal in shearing the uneven ends of the
plates (as generally made) will be avoided. We would further remark that the
thin sheet of metal as it rapidly emerges from between the rolls in a heated state
may in some cases be made to pass between another pair of rolls, preferably of
much less diameter than the main rolls, and may here undergo a further reduction
in thickness, care being taken to speed these rolls so as to work properly in con-
junction with the main rolls; or in lieu of this mode of operating we prefer to
allow the thin sheet as it emerges from the main rolls to pass between guide plates,
which will conduct it into the jaws of a pair of vertically acting shears operated on
by a cam so as to make a very rapid movement through a very small distance, and
thus cut off the issuing sheet into such lengths as may be desired, and which will
be regulated by the relative velocity of the cam shaft and the main rolls; or in
lieu of the reciprocating shears a revolving bar or cutter, shod at one or both ends
with an adjustable cutter, may be made to shear the metal into the lengths desired.
In either case we place below the shearing apparatus a tank partly filled with
water, oil, or other fluid, into which the plates as sheared off may fall, and thus
prevent that oxidation of the surface which slowly cooling in the air would produce.
If water acidulated with sulphuric or hydrochloric acid be employed the plates will
be effectually cleaned of any external film of oxide. In some cases it may be pre-
ferred to retain the long sheet of thin metal in a continuous piece, in which case we
provide a revolving drum having a notch or opening on one side, the drum having
its axes parallel to the axes of the main rolls, and so placed near the end of the
guide plates that the sheet of thin metal may be directed into the notch before
named, where pushing against a catch it will be locked fast to the drum, and at
the same time throw the axis of the drum into gear with a revolving shaft, so that
the thin sheet of metal may be wound up on the drum as fast as it is produced, the
drum being replaced by an empty one for the next rolling operation; and in order
that this mode of winding up the long sheet of thin metal on a drum as it emerges
from the rolls may be fully understood, we have shewn so much of the apparatus
as is necessary for this purpose at Figure 1 on Sheet C of the annexed Drawings,
where a represents the shaft on which the winding drum b is mounted. The shaft a
may be supported on brackets projecting from the housings of the rolling mill, or
in a separate frame, and be driven by an ordinary driving drum and strap. The
driving drum should be provided with a friction clutch, which will enable the
driving drum to revolve without carrying the axle a with it whenever the winding

page_text: drum is held fast, but which will nevertheless cause the axle a and the winding
drum b to revolve the moment the winding drum is allowed to do so. The sheet
of thin metal C passes between horizontal guide plates d, and entering the notch or
opening of the winding drum comes in contact with a small catch e, which it pushes
forward into the cavity f formed behind the thickened edge of the opening into the
drum. A lever g, mounted on a pin or centre h, has a very stout spring i pressing
on one end of it; the opposite end is corrugated, and when released from the position
shewn in the Drawing by the movement of the catch e the corrugated part suddenly
moves upward, gripping the end of the plate o firmly between it and a similarly
corrugated part formed on the inside of the drum at 61. This movement of the
lever g causes the pin or stop n attached to the lever g to be withdrawn from contact
with a fixed stop m, which up to that time had prevented the winding drum from
revolving, but which will by its removal allow the winding drum to revolve in the
direction indicated by arrows, and wind up the thin plate of metal as fast as it
emerges from the rolls. A portion of the drum 62 is hinged at 63 to the other part
of the drum, and its upper end is held in position by jointed levers p, p, which hold
it in the position shewn during the winding up of the thin plate, but as soon as
this is done the levers p, p, are forced upward into the position shewn by dots,
which will move inward or collapse one side of the winding drum, and allow the
coil of thin plate to be readily removed, the winding drum being mounted outside
its bearings for the purpose of facilitating the removal of the coil of plate.
If it be desired to make the edges of the thin plates more perfect than they are
produced by the rolling operation we use a pair of revolving shears between the
main rolls and that part of the apparatus where the thin sheet is cut into lengths or
wound on a drum, or is otherwise disposed of; these shearing rolls consist of a plain
roll of an exact length corresponding with the intended breadth of the plate, and a
second roll of the same length on which two circular discs are mounted, forming &
sort of raised flange at each end with sharp chisel-like cutting angles which will cut
off the uneven edges and render the sheet of metal even and parallel throughout its
length, by which arrangements or some of them the length of tin plate bar when put
into the rolling machine will be converted without labour or reheating in the
furnace into a great number of thin plates sheared to the desired length and breadth,
and delivered into the pickling tank almost free from external scale, and in a very
short period of time.
These shearing rolls detached from the rolling mill are shewn in elevation at
Fig. 2 on Sheet C of the annexed Drawings, where 1 represents the body of the
upper roll, having at each end a steel collar 2, the thickness of which regulates the
distance between the tempered steel shearing discs 3, 3, which are held in place by
the nuts 4, 4; a similar roll 5 has at each end a tempered steel collar or cutting
disc 6, 6, the outer angle of which, in conjunction with the bevilled edges of the
discs 3, 3, form the shearing part of the rolls, so that a sheet of metal whose width
exceeds the distance apart of the cutters 3, 3, will have such superfluous metal
sheared off, and be reduced to a parallel plate of the width between the cutters 3, 3.
When such rolls are to be employed in connection with the rolling apparatus shewn
at Figures 1, 2, and 3, on Sheet B, we prefer to place them in such a position that
the thin sheet of metal issuing from the rolls may be received by them, so that the
shearing of the plate may be effected prior to the sheet of metal reaching the
revolving cutter, by which it is cut into separate plates, the cutting apparatus used
for this latter purpose being in that case placed a little further from the main rolls
in order to make room for these shearing rolls between it and the main rolls; these
rolls may be driven by tooth gearing on the main driving shaft, the speed being
such as to shear the edges as fast as the sheet emerges from the main rolls.
The plates when cooled down in the tank, either with or without being annealed,
may be wiped dry and be flattened and smoothed only, or they may be further
extended if desired by cold rolling between polished cast steel rolls or highly
polished chilled rolls set to a definite distance apart by screws, or, as we prefer when
used only for improving the surface of the plate, forced together by hydraulic

page_text: cylinders actuated by an accumulator of small size under spring pressure, the cold
rolling apparatus having a table at each side, the surface of which is at a tangent
with the upper surface of the bottom roll, and will admit of the rapid passage of
plates between them.
A pair of rolls suitable for cold rolling the thin plates is shewn in cross section at
Figure 3, Sheet C; these rolls may be mounted in frames such as are generally
employed for rolling plate iron, and be driven in the ordinary way. We prefer that
hard steel rolls should be used for this purpose, or chilled iron ones having smooth
and well polished surfaces. We fix an iron table B, B, on each side of the lower
roll. The top of the table should be planed flat, and its surface fixed at a tangent
to the upper surface of the lower roll, so that a pile of plates placed on one table
may be rapidly passed singly or otherwise between the rolls, and be received and
piled upon each other at the other side, or be returned once or more times between
them, as found desirable, so as to flatten, extend, and improve the surface of the tin
or black plate so operated upon.
We desire further to observe that although we have hereinbefore shewn and
described a method by which tin plates or black plates may be produced by a
single pass of the tin plate bar through the rolls, and how the surface of thin
plates so produced may be further extended or improved by a subsequent process
of cold rolling, we nevertheless desire it to be understood that when thin plates
are made from tin plate bar by a single pass through the rolls that such thin plate
may be still further reduced in thickness when found desirable or necessary by
hot rolling the same either in single thicknesses or when the same has been doubled
once or more times, and that in all such cases we prefer to heat the plates for the
rolling operation in retorts or chambers from which the products of combustion
are excluded.
And in order that the general arrangement and mode of constructing a rolling
apparatus suitable for the purposes of our Invention may be fully understood we
have shewn the same on Sheet B of the Drawings annexed, where Figure 1 is a
vertical cross section on the line A, B, of Figures 2 and 3 on the same Sheet;
Figure 2 being a front elevation, and Figure a plan of the same. In these Figures
A, A, represent the two main frames or housings of the rolling mill secured by
bolts and wedges to the foundation plate B. The upper part of these frames have
projecting flanged pieces A' cast upon them for the purpose of holding them firmly
together; they are further secured in position by keys passing vertically and
horizontally in grooves between them as shewn. On the front side of the frames A
protecting pieces A² are cast, into which the brasses C of the feeding rolls D, D,
are fitted. The main rolls E, E, work in brasses shewn by dots at F in the main
frames A, the screws G serving to regulate the thickness of the plate; any
alteration of this thickness by turning the screws G is shewn by the divided dises
mounted on the screws G; against the edges of these discs a pointer is fixed.
The top main roll is held in place firmly upward against its bearings by means of
the ram H carrying the brass I. This ram works in a cylindrical recess formed
in the main frames as shewn by dots, one such ram and cylinder being employed
beneath each of the journals of the top roll. The brasses of the lower main roll have
wedged shaped recesses formed at their lower angles, into which steel wedges J, J,
are accurately fitted, and by means of which these lower brasses may be adjusted
so as to insure the true parallelism of the upper and lower rolls.
The feeding rolls D, D, may be adjusted by the screws K, but we prefer to support
the brasses of the upper roll so that it is suspended at a short distance above the
tin plate bar, while the lower roll sinks down sufficiently low to admit the introduction
of the tin plate bar, freely between them, the bar being supported on the cross
ribs L' of the guide frame L. When the bar is thus introduced between the rolls D
and is pushed forward nearly in contact with the main rolls, the workman will
by means of a suitable handle open a communication between the accumulator
before referred to and the small rams M. The pipe of communication is shewn
broken off at N; by this means the lower feeding roll will be lifted up, carrying

page_text: the tin plate bar with it and forcing it in contact with the upper feeding roll. The
powerful grip of these rolls will carry the tin plate bar forward and force its tapered
end into the narrow space left between the main rolls. It will be understood that
both the feeding and inain rolls are kept revolving by a powerful engine, and are
coupled and geared together after the manner usually employed in rolling mills, and
which gearing is therefore omitted in these Drawings. As the metal emerges in a
thin sheet from between the rolls E it passes over the guide plate O, passing also
over the lower portion P of the shears which is bolted to the main framing of the
rolls. A frame Q is bolted securely to the bed plate B, and is further secured in
place by stretcher bars R to the frames A, A, of the rolls. A shaft S is fitted into
sliding brasses T which move in horizontal slots formed in the upper parts of the
frame Q. This shaft has keyed upon it a revolving frame U to which a steel cutting
bar V is bolted. The opposite end of the revolving frame has projecting pieces U¹
which serve to balance the weight equally on each side of the spindle Ş. A bar W
is bolted to the main frames A having two curved projections W' formed upon it;
these curves are slightly eccentric to the circular path of the cutting blade V; the
distance apart of this revolving cutting blade V and the fixed cutter P is regulated
by the screw X. At the opposite end of the slot is also a screw Y which acts in a
strong spiral spring Z and forces the sliding brasses and axle S in the direction of
the cutter P. It will be seen that the frame U has projecting parts U', seen best in
Figure 4, which is a plan of the revolving cutter and its frame. These projections
slide over the curved surfaces W¹ and prevent the two cutting edges from coming
in forcible contact with each other, the piece, of thin plate thus sheared off falls into
the tank a, a, beneath the cutting apparatus. It will be understood that the axis S
may be driven by a drum and strap or by change wheels so as to alter at pleasure
its rate of rotation relatively to the speed at which the main rolls are driven, and
thus the length of the plates sheared off may be made to vary as may be found
desirable. We have also mentioned that the cooling of the brasses and journals of
the rolls may be found necessary when such rolls are driven at high speeds under
heavy pressure, for which purpose water under pressure is conveyed by branch
pipes as herein before referred to, and we prefer when so cooling the brasses and
journals to form passages for its distribution over their surfaces, as shewn in
Figures 5 and 6 on Sheet B, where b shews the junction of the pipe conveying the
water; and c, c, the passages for its distribution for the purpose of effectually
cooling the brasses and journals of the rolls.
Having described our Invention, and the manner in which the same may be
carried into practical operation, we desire it to be understood that we do not confine
ourselves to the precise details herein described so long as the peculiar principles of
our Invention are retained, but what we do claim and desire to secure by these
Letters Patent is as follows:-
First. The method of reducing heated tin plate bar to plate at one passage
between the rolls, the bar being thus extended to many times its original length,
and requiring no further hot rolling.
Second. The preparation of the tin plate bar, ensuring true and clear surfaces,
free from scale, being presented to the rolls by which the bar is at one operation
reduced to plate.
Third. The combination with the rolls by which the tin plate bar is at once
extended to many times its original length and reduced to plate of nipping and
propelling instruments by which the bar is forced to enter the nip of the reducing
rolls.
Fourth. The combination of reducing rolls and nipping and propelling instruments
forcing the tin plate bar to be taken by the reducing rolls, and of cutting apparatus
automatically dividing the plate into suitable lengths as it issues from the rolls.
Fifth. The combination with reducing rolls, by which tin plate bar is at one
operation extended to many times its original length and reduced to plate, of
winding apparatus automatically coiling up the plate as it issues from the reducing
rolls.

page_text: Sixth. The production of "black plate," or plate from which tin or plate is made
from ingot metal by presenting a suitably prepared bar of such metal to rolls by
which at one passage between the rolls the bar is reduced to plate, being extended
to many times its original length.
Seventh. The general arrangement and construction of the hydraulic shearing
apparatus for preparing the tin plate bar for the reducing rolls.
Eighth. The process of simultaneously shearing off and tapering by pressure
by which the ends of the tin plate bars are adapted to enter between the reducing
rolls.
Ninth. The process of passing heated tin plate bars between bending rolls to
remove oxide or scale, and then immediately between reducing rolls, by which at
one operation they are extended to many times their original length and reduced to
plate.
Tenth. The process in the manufacture of black plate or plate from which tin
plate is made of simultaneously rolling and automatically shearing the plate issuing
continuously from the rolls into suitable lengths.
Eleventh. The process of heating tin plate bars in retorts or closed chambers and
then rolling the same at one operation, and by a single passage between the reducing
rolls into plates many times the length of the bar.
Twelfth. The process in the production of "black plate," or plate from which the
tin plate is made, of simultaneously rolling, cutting, and receiving the cut off plates
into a tank containing a suitable liquid.
Thirteenth. The process of grinding tin plate bars, and of heating the said bars
in retorts or closed chambers to improve and preserve the surfaces presented to the
rolls.
Fourteenth. The means for preserving from injury the surfaces of the reducing
rolls by which tin plate bar is at one operation reduced to plate by the application
of hydraulic cylinders to sustain the upper roll and effectually prevent it from
falling into contact with the lower roll when the thin plate passes from between
them.
Fifteenth. The means for preventing the heating of the bearings of the reducing
rolls by which tin plate bar is at once reduced to plate, by causing water at high
pressure to enter passages formed in the brass and to issue between the neck of the
roll and the brass.
Sixteenth. The production of "black plate," or plate from which tin plate is
made, by means and apparatus substantially as described and represented in the
Drawings annexed.
In witness whereof, we, the said Henry Bessemer and Alfred George Bessemer,
have hereunto set our hands and seals, this Fourth day of October, in
the year of our Lord One thousand eight hundred and seventy nine.