IMPROVEMENTS IN PREPARING AND MANUFACTURING TIN-PLATE BAR OR SLABS OF METAL SUITABLE FOR THE MANUFACTURE OF TIN OR BLACK PLATES, AND ALSO IN THE PROCESSES AND MACHINERY EMPLOYED FOR SUCH PURPOSE."
Year: 1879

page_text: LETTERS PATENT to Sir 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
PREPARING AND MANUFACTURING TIN-PLATE BAR OR SLABS OF METAL
SUITABLE FOR THE MANUFACTURE OF TIN OR BLACK PLATES, AND ALSO IN
THE PROCESSES AND MACHINERY EMPLOYED FOR SUCH PURPOSE."
PROVISIONAL SPECIFICATION left by the said Sir Henry Bessemer and
Alfred George Bessemer at the Office of the Commissioners of Patents on the
10th October 1879.
Sir 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 PREPARING AND MANUFACTURING TIN-PLATE BAR OR SLABS
OF METAL SUITABLE FOR THE MANUFACTURE OF TIN OR BLACK PLATES, AND
ALSO IN THE PROCESSES AND MACHINERY EMPLOYED FOR SUCH PURPOSE."
This Invention has for its object, firstly, the preparation and production of tin-
plate bars or slabs or plates of homogeneous malleable-iron suitable for the manu-
facture of tin or black plates by the employment of a cheap material which in its
ordinary marketable condition is neither suitable in form or in chemical composition
for this purpose, but which is nevertheless by means of our Invention so altered in
form and in its chemical constituents as to render it capable of being made with
facility into tin or black plates at a considerable reduction in cost below that at
which tin and black plates of equal quality are at present made.
It is well known that very large quantities of Bessemer steel rails have for
many years been employed on railways, and that by continued use such rails
become so much worn as no longer to be suitable for their original purpose, but
which rails are nevertheless composed of good homogeneous metal, which is however
too highly carburized or steely in quality for the production of ordinary tin or black
plate, and we would further remark that both the custom of the iron and steel
trades, and the great competition which exists in the manufacture of steel rails,
combined with other causes, has hitherto had the effect of reducing the selling price

page_text: of new steel rails much below the price at which steel merchant bars of plain,
square, or rectangular sections are usually sold, and so long as this practice continues
of selling rails at prices much below the cost of other descriptions of bars, the
manufacturer of tin or black plate who does not convert the raw pig into homo-
geneous metal, but prefers to purchase metal that has been already converted into
steel, will find it advantageous to purchase such steel after it has been made into
railway bars, either old or new, and by means of the processes which we have
devised for that purpose convert such steel railway bars into tin plate bar of a
suitable quality for the manufacture of tin or black plates of soft malleable iron.
But it will be obvious that in all cases where the manufacturer of tin or black
plates is also the manufacturer of the homogeneous metal used for such purpose,
that he will find it still more advantageous to roll his ingots into slabs or bars of a
plain rectangular form in cross section, and specially adapted for their intended
purpose, and thus avoid the cost due to the alteration of form necessary when a rail
section has to be altered into such plain bar, but when extremely soft metal, wholly
or almost wholly decarburized, is to be employed in this manufacture, it will be
found that there are great difficulties in producing such wholly decarburized iron
which shall at the same time possess all the other requisite qualities of a good
workable metal at different temperatures, and that the extra cost of the ferro-
manganese usually employed in cases where very mild metal is required will render
it advantageous to convert the pig iron into mild steel, as commonly practiced by
the use of the cheaper material spiegleisen, and aferwards to convert this mild steel
into soft iron by the complete decarburization of it while in a solid form in the
manner hereinafter described.
In carrying our said Inventions into practical operation we prefer to employ the
kind of rails commonly known as double headed rails, which may be sheared into
convenient lengths when cold, or sawn into pieces while hot; or if preferred they
may be operated upon while still retaining their original length. Such rails or
pieces of rail may be heated in a long reverberatory furnace placed near the rolls
where they are to be operated upon. In those cases where the head of the rail has
been worn very thin, and in some other cases also, a preliminary hammering will
be found advantageous, so as to reduce somewhat the breadth of the head before
the rolling process takes place, and for which rolling process we prefer to employ a
pair of grooved rolls mounted and driven in a manner similar to the rolls in general
use for rolling rails, but the grooves therein differ considerably both in their form
and in their mode of acting on the metal. These grooves are made with bevilled
or curved surfaces so arranged as to reduce the breadth of both heads of the rail,
forcing out the metal laterally, so as to add to the breadth of the central web
without greatly increasing its length. Several such grooves are used in succession,
each contributing to the flattening down of the head and the widening of it until it
forms a broad flat plate or bar not very much less in thickness than the original
web of the rail, but of considerably increased breadth. The uneven edges of the
bar thus formed may be sheared if necessary to a width suitable for the tin or black
plate to be made therefrom. In lieu of this mode of treating the rail by rolling
lengthwise it may be cut into lengths of three to five feet, and then passed crosswise
several times between a pair of plain plate rolls until both heads of the rail are
flattened down, and forin with the central web a flat uniform slab or tin plate bar,
which may then be sheared into rectangular pieces of a size suitable for the particular
mode of manufacture to be afterwards pursued.
And in order to render such pieces of bar suitable for the manufacture of tin or
black plate we proceed to decarburize the metal and convert it into soft iron, for
which purpose we prefer to employ a series of vertical cast iron or steel retorts set
in a suitable furnace. The retorts may be square or rectangular in cross section,
passing through the upper part of the furnace, and there closed with a suitable lid
The lower ends pass through the lower part of the furnace, and have
beneath them a flat iron bed or grating, on which the column of plates occupying
these retorts are allowed to rest. The pieces of tin plate bar are packed one above
or cover.

page_text: another in these retorts, with a thin layer between and around them of iron ore or
other oxide of iron, oxide of manganese, or other matter capable of decarburizing
the plates and converting them into soft malleable iron.
A high temperature should be steadily maintained in the retort furnace, and
when once the system has got into full operation a portion of the plates forming the
lower part of the column are to be pushed out from time to time by means of a
sliding piece actuated by a crank motion, removing the lower pieces of the column,
and thus allowing the whole column to sink down, leaving a vacancy in the upper
part of the retort, which may then be filled with more plates and oxide, thus ren-
dering the process continuous. Several such retorts may be placed side by side in
one or more rows in each furnace.
When the pieces of tin plate bar are of such a length as to render this continuous
process inconvenient we prefer to uso horizontal retorts of fire clay, cast iron, or
steel, and to pack the tin plate bars in iron boxe³ with the powdered oxide between
them, and then push them into the retorts, from which they can be conveniently
withdrawn so soon as the process of decarburization is completed.
The annealed or decarburized pieces of tin plate bar may then be pickled in dilute
sulphuric or hydrochloric acid, or otherwise cleansed, and may then be rolled into
tin or black plates after the manner set forth in a Patent granted to us for
"Improvements in the Manufacture of Tin Plate and Black Plate, and in the
Machinery, Apparatus, and Processes Employed in such Manufacture," bearing date
the Fifth day of April 1879, and numbered 1368.
Or in lieu of this mode of manufacturing tin or black plates the tin plate bar
produced from old or new railway bars or from other pieces of decarburized steel
may be treated and worked by any of the methods now successfully applied to the
manufacture of tin or black plates.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Sir Henry Bessemer and Alfred George Bessemer in the Great Seal
Patent Office on the 10th April 1880.
Sir 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 PREPARING AND MANUFACTURING TIN PLATE BAR OR SLABS
OF METAL SUITABLE FOR THE MANUFACTURE OF TIN OR BLACK PLATES, AND ALSO
IN THE PROCESSES AND MACHINERY EMPLOYED FOR SUCH PURPOSE.”
This Invention has for its object, firstly, the preparation and production of tin
plate bars or slabs or plates of homogeneous malleable iron suitable for the manu
facture of tin or black plates by the employment of a cheap material which in its
ordinary marketable condition is neither suitable in form or in chemical composition
for this purpose, but which is nevertheless by means of our Invention so altered in
form and in its chemical constituents as to render it capable of being made with

page_text: facility into tin or black plates at a considerable reduction in cost below that at
which tin and black plates of equal quality are at present made.
It is well known that very large quantities of Bessemer steel rails have for many
years been employed on railways, and that by continued use such rails become so
much worn as no longer to be suitable for their original purpose, but which rails
are nevertheless composed of good homogeneous metal, which is however too highly
carburized or steely in quality for the production of ordinary tin or black plate,
and we would further remark that both the custom of the iron and steel trades, and
the great competition which exists in the manufacture of steel rails, combined with
other causes, has hitherto had the effect of reducing the selling price of new steel
rails much below the price at which steel merchant bars of plain, square, or rectan-
gular sections are usually sold, and so long as this practice continues of selling rails
at prices much below the cost of other descriptions of bars, the manufacturer of tin
or black plate who does not convert the raw pig into homogeneous metal, but
prefers to purchase metal that has been already converted into steel, will find it
advantageous to purchase such steel after it has been made into railway bars, either
old or new, and by means of the processes which we have devised for that purpose
convert such steel railway bars into tin plate bar of a suitable quality for the
manufacture of tin or black plates of soft malleable iron.
But it will be obvious that in all cases where the manufacturer of tin or black
plates is also the manufacturer of the homogeneous metal used for such purpose,
that he will find it still more advantageous to roll his ingots into slabs or bars of a
plain rectangular form in cross section, and specially adapted for their intended
purpose, and thus avoid the cost due to the alteration of form necessary when a
rail section has to be altered into such plain bar.. But when extremely soft metal,
wholly or almost wholly decarburized, is to be employed in this manufacture, it will
be found that there are great difficulties in producing such wholly decarburized iron
free from blow holes more or less distributed throughout the ingot, and free from
those long central hollows called piping, so common in steel that has been almost
wholly decarburized, and which shall at the same time possess all the other requisite
qualities of a good workable metal at different temperatures. Also that the extra
cost of the ferro-manganese, usually employed in cases where very mild metal is
required, will render it advantageous to convert the pig iron into mild steel as
commonly practised by the use of the cheaper material spiegeleisen, and afterwards
to convert this mild steel into soft iron by the complete decarburization of it while
in a solid form, in the manner hereinafter described.
In carrying our said Invention into practical operation we prefer to employ the
kind of rails commonly known as double headed rails, which may be sheared into
convenient lengths when cold, or sawed into pieces while hot, or if preferred they
may be operated upon while still retaining their original length. Such rails or pieces
of rail may be heated in a long reverberatory furnace placed near the rolls where
they are to be operated upon. In those cases where the head of the rail has been
worn very thin, and in some other cases also, a preliminary hammering will be found
advantageous so as to reduce somewhat the breadth of the head before the rolling
process takes place, and for which rolling process we prefer to employ a pair of
grooved rolls mounted and driven in a manner similar to the rolls in general use
for rolling rails, but the grooves therein differ considerably both in their form and
in their mode of acting on the metal. These grooves are made with bevilled or
curved surfaces so arranged as to reduce the breadth of both heads of the rail,
forcing out the metal laterally, so as to add to the breadth of the central web
without greatly increasing its length. Several such grooves are used in succession,
each contributing to the flattening down of the head and the widening of it until
it forms a broad flat plate or bar not very much less in thickness than the original
web of the rail, but of considerably increased breadth. The uneven edges of the bar
thus formed may be sheared if necessary to a width suitable for the tin or black;
plate to be made therefrom.
A pair of rolls suitable for this purpose is shown in elevation on Sheet 3 at a, a,

page_text: of the annexed Drawings. These rolls have a series of wide shallow grooves
formed
around them, each of which is a little wider and less in depth than the preceding
one. On the same Sheet we have shewn at b a section of the double headed rail to
be operated upon. In passing between the rolls it will first assume the sectional
form shewn at c; a second pass between them will further widen the central web
and at the same time extend the breadth of the head, as shewn at d. This action
is again repeated in the third groove, where the section e shows the head still further
widened out, and the thickness of the web somewhat reduced, while the fourth pass
through the plain surface of the rolls will produce the flat plate or tin plate bar
shewn at f. It will be understood that suitable guides are to be employed in this
rolling-mill, such as are commonly employed in rolling merchant-bars, and also that
the form and number of grooves may be varied to suit the form of rail to be
operated upon.
In lieu of this mode of treating the rail by rolling lengthwise it may be cut into
lengths of three to five feet, and then passed crosswise several times between a pair
of plain plate rolls until both heads of the rail are flattened down and form with
the central web a flat uniform slab or tin plate bar, which may then be sheared
into rectangular pieces of a size suitable for the particular mode of manufacture to
be afterwards pursued.
In some cases where the head of the rail may have been worn very thin, and also
in the case of rails having a wide and thin bottom flange, it may be found advan-
tageous to cut or shear off these projecting parts from each side of the rail level or
nearly level with the central web, so as to obtain at once a bar whose breadth is
equal to the entire height of the rail. The metal so sheared off may be either rolled
into small sections for other purposes or simply treated as scrap metal. Many modes
of arranging a revolving shearing apparatus might be employed for this purpose,
but as such apparatus forms of itself no part of the Invention which we desire to
secure by these Letters Patent we have given no details thereof, but only desire it
to be understood that rails so treated would be suitable for the manufacture of tin
plate bar when decarburized in the manner hereinafter described.
And in order to render such pieces of bar suitable for the manufacture of tin or
black plate, we proceed to decarburize the metal and convert it into soft iron, for
which purpose we prefer to employ a series of vertical cast iron or steel retorts set
in a suitable furnace. The retorts may be square or rectangular in cross section,
passing through the upper part of the furnace, and there closed with a suitable lid or
cover; the lower ends pass through the lower part of the furnace and have beneath
them a flat iron bed or grating on which the column of plates occupying these
retorts are allowed to rest. The pieces of tin plate bar are packed one above another
in these retorts with a thin layer between and around them of iron ore or other
oxide of iron, oxide of manganese, or other matter capable of decarburizing the
plates and converting them into soft malleable iron.
A bigh temperature should be steadily maintained in the retort furnace, and when
once the system has got into full operation a portion of the plates forming the
lower part of the column are to be pushed out from time to time by means of a
sliding piece actuated by a crank motion, removing the lower pieces of the column,
and thus allowing the whole column to sink down, leaving a vacancy in the upper
part of the retort which may then be filled with more plates and oxide, thus ren-
dering the process continuous. Several such retorts may be placed side by side in
one or more rows in each furnace. When the pieces of tin plate bar are of such a
length as to render this continuous process inconvenient, we prefer to use horizontal
retorts of fire clay, cast iron, or steel, and to pack the tin plate bars in iron boxes
with the powdered oxide between them, and then push them into the retorts, from
which they can be conveniently withdrawn so soon as the process of decarburization
is completed.
The annealed or decarburized pieces of tin plate bar may then be pickled in
dilute sulphuric or hydrochloric acid, or otherwise cleansed, and may then be rolled
into tin or black plates, after the manner set forth in a Patent granted to us for

page_text: "Improvements in the Manufacture of Tin Plate and Black Plate, and in the
Machinery, Apparatus, and Processes Employed in such Manufacture," bearing date
5th day of April 1879, and numbered 1368.
Or in lieu of this mode of manufacturing tin or black plates, the tin plate bar
produced from old or new railway bars, or from other pieces of decarburized steel,
may be treated and worked by any of the methods now successfully applied to the
manufacture of tin or black plates.
And in order that the process and apparatus which we prefer to employ for the
decarburization of steel bars (whether produced from old or new rails, or from
ingots of steel that have been rolled direct into tin-plate-bar) may be fully under-
stood, we have represented the apparatus on Sheets 1, 2, and 3 of the Drawings
annexed.
Figure 1, Sheet 1, is a front elevation of the decarburizing furnace; Figure 2,
Sheet 1, in a longitudinal vertical section of the same; and Figure 3, Sheet 1, is a
sectional plan on tho line A, B, of Figure 2 ou the same Sheet. An end elevation
of the furnace is also shown at Figure 4, and a vertical cross section of Figure 5
taken on the line C, D, of Figure 3. Another vertical section is shown at Figure 6
taken on the line E, F, of Figure 3, and passing through the combustion chamber
and flues of the furnace.
On Sheet 2 of the annexed Drawings, plans and sections of some parts are
shown on
a larger scale, and lettered to correspond with the lettering on
Sheet 1.
Figure 1, Sheet 2, is a vertical cross section taken through the furnace on the
line C, D, of Figure 3, Sheet 1, showing the decarburizing retorts partly in
elevation and partly in section. Figure 2, Sheet 2, is a sectional plan taken on
the line G, H, of Figure 1, Sheet 2. Another vertical cross section is also shown
at Figure 3, Sheet 2, taken ou the line K, L, of Figure 2. A cross section is also
shown at Figure 4, Sheet 2, taken on the line M, N, of Figure 2, Sheet 2;
it repre-
sents more clearly the sliding plate employed for pushing out the pieces of decar-
burized steel bar.
We would here remark that in the annexed Drawings we have shown an
arrangement suitable for heating the retorts either by means of the waste gases of
the blast furnace, or by carbonic oxide gas generated for that purpose; but it will
be obvious that in lieu of this mode of heating the furnace, each end may, if pre-
ferred, be provided with fire-bars and a sufficiently large fire-place so as to render
it suitable for the combustion of solid fuel as commonly practised in puddling and
other similar furnaces.
The decarburizing furnace is constructed with fire-brick walls a, supported by
iron stays b (or it may, if preferred, be entirely encased in iron). The central
portion of the furnace contains a number of square vertical retorts c made of cast-
iron or cast-steel. These retorts for the convenience of renewal are fitted into
sockets formed in similar short lengths of the same section c, which are protected
from the direct action of the fire by being embedded in the brick-work a* which
forms the bed of the furnace. The retorts pass upward through the roof of the
furnace as shown, and are provided with hinged covering-plates d. Beneath each
group of four retorts there is an iron frame or bed-plate e, on which the lower
portion of the retorts c¹ rest, and to which they are bolted by the flanges c³.
The underside of these retorts are planed true, and do not extend so far down-
ward as to come in contact with the bed plate e except at the sides where the
flanges c² are formed, as shown in Figure 4, Sheet 2.
That part of the bed plate e immediately beneath each group of four retorts is
planed flat, and has a groove e' running across its central part, in which the sliding
block is free to move, and to which the steel plate g is bolted.
It will be observed that the underside of the retorts (which are supported by the
flanges) are so far above the upper surface of the steel plate g as to allow it to
slide freely beneath them whenever the sliding-block f is moved backward or
forward. That portion of the bed-plate e beyond the part where the retorts rest is