IMPROVEMENTS IN Apparatus FOR THE MANUFACTURE OF MALLEABLE CAST IRON
Year: 1875

page_text: LETTERS PATENT to John Tenwick, of Grantham, in the County of
Lincoln, Moulder, for the Invention of "IMPROVEMENTS IN Apparatus
FOR THE MANUFACTURE OF MALLEABLE CAST IRON."
Scaled the 29th February 1876, and dated the 3rd September 1875.
PROVISIONAL SPECIFICATION left by the said John Tenwick at the
Office of the Commissioners of Patents, with his Petition, on the
3rd September 1875.
I, JOHN TENWICK, of Grantham, in the County of Lincoln, Moulder,
do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN APPARATUS FOR THE MANUFACTURE OF MALLEABLE CAST IRON," to be as
follows:-
The chief object of this Invention is to facilitate the operation of
annealing articles of malleable cast iron, and prevent the loss by breakage
and deformity which is apparently unavoidable in annealing by the
ordinary process.

page_text: My Invention consists in constructing annealing ovens or furnaces in
the following manner:-I make the outside shell or case of the oven of
wrought or cast iron, but of preference wrought-iron boiler plate, and
of the ordinary form; I line the outside shell with fire-brick, and the
top part I form with a chamber, through which I causo the flame or
heated gases to pass to the exit chimney. This chamber I use for light
articles that do not require so much annealing; the bottom of this
chamber forms the top part of the lower compartment of the oven. At
a suitable distance from the bottom of oven I form a metal flange or
shelf on the two interior sides and at one end of oven, to support the
inside lining, and likewise to strengthen the oven. On this shelf I keep
a quantity of sand to exclude the cold air from entering the oven when
thic fire-box and the annealing chambers are in their proper position,
that is to say, when the fire-box and annealing chamber are on the line
of rails which is laid at the bottom of oven for that purpose.
In forming the moveable and inner part, which I call the fire-box and
anncaling chamber, I construct a carriage with wheels to fit the tramway
in bottom of oven, and two of these carriages form part of one oven, but
I do not confine myself to size of the carriages or oven. On these
carriages I build with fire-brick and fire-clay a fire-place for one or morc
fires, and I connect the same with vertical and horizontal tubes of firc-
clay or metal, which tubes are removed with the charge and relaid when
the chambers are packed with the articles that require to be annoaled.
In the walls of the annealing chambers I insert holding irons to connect
the tie rods for securing the two outer walls of the annealing chamber
from bulging outward by the expansion of the material that has to be
annealed. In these chambers I pack with iron ore or other suitable
material the articles that have to be annealed, and I place the fire-clay
or metal tubes in suitable positions and at proper distances from each
other to convey the fire to all parts at the same time through the bulk
that has to be annealed equally alike, which is impossible to do in the
ordinary way of anncaling; I thus ensure one uniform heat through the
whole bulk at the same time. I place a tube as near the centre of the
bulk as I possibly can in connection with front part of oven in order to
watch the process; and in front of oven and attached to fire-box I have
firing doors, two flue doors, one on each side, one double door on
annealing chamber for discharging same; two vertical ribs on the
.

page_text: bottom of carriage that are bedded in the sand, provided for preventing
cold air entering the oven when at work, and the fire-box end is made
to form one end of the oven. The annealing chamber fills the oven
with the exception of a space of about four inches allowed over the
top and around the end and sides for the fire to work from the
vertical and horizontal flues, and from them to the upper annealing.
chamber.
The charging door of the upper chamber can be made of any con-
venient shape on either side or end of oven, which may be most
convenient, and opened or shut in ordinary manner.
I thus ensure a
smokeless and nearly a continuous working oven, as the charge can be
drawn and another inserted with fires up to the mark required within
five minutes.
All repairs to fire-box can be done outside over a pit while the annealing
chamber is being repacked.
By this apparatus I am enabled to dispense with the cast-iron pans
or cases, the chief cause of the many evils attending the manufacture
of malleable cast iron, and to reduce the cost of production nearly one-
half.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Tenwick in the Great Seal Patent Office on
the 3rd March 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
TENWICK, of Grantham, in the County of Lincoln, Moulder, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Third day of September, in the
year of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-
> ccssors, give and grant unto me, the said John Tenwick, Her special
license that I, the said John Tenwick, my executors, administrators,

page_text: exclude the cold air from entering the oven when the annealing box H,
n which is a fire-place I and an annealing chamber J, is in its position
within the oven F and on the line of rails L, which is laid at the bottom
or floor for that purpose.
The annealing box or carriage has wheels M, M, to fit the tramway L
in the bottom of the oven. I purpose using two of these carriages for
one oven, so that when one carriage is withdrawn the other charged can
be run in. In these carriages, which I build with fire-brick and fire-
clay in sections, is a fire-place I for one or more fires, and I connect the
fire-chamber with the oven proper by vertical and horizontal tubes N, N,
also of fire-clay or of metal, which tubes are removed with the charge
and relaid when the annealing box is packed with the articles which
require to be annealed. In the walls of the oven I insert holding
irons P, P, which connect by the tie rods Q, Q, the two outer walls of the
oven and annealing box, and prevent the sides from bulging outward
by the expansion of the material that has to be annealed. In the
chambers I pack the articles that have to be annealed with iron ore or
other suitable material in combination, and I place the firc-clay or metal
tubes in suitable positions and at proper distances from each other to
convey the fire to all parts at the same time through the bulk that has
to be annealed equally alike, which it is impossible to do in the ordinary
way of annealing. I thus ensure one uniform heat through the whole
bulk of articles at the same time. I place a horizontal tube as near the
centre of the bulk as I possibly can in connection with the front part
of the oven, in order that an attendant can watch the process; and in
front of the annealing box and attached to the fire-place I have firing
doors R, two flue doors S, S, one on each side, one double door T for
discharging, two ribs on the bottom of carriage which become embedded
in the sand V as a lute joint for preventing cold air entering the oven
when it is at work. The fire-box end is made to form one end of the
annealing box, which fills the oven with the exception of a space of
about four inches allowed over the top and around the end and sides for
the fire to work from the vertical and horizontal flues, and from them to
the upper annealing chamber.
The charging door of the upper chamber can be made of any convenient
shape, and fitted on either side or end of the oven, which may be most
convenient and it can be onened or shut in any ordinary manner.

page_text: By my Invention I ensure a smokeless and a nearly continuous
working oven, as the box containing the charge can be withdrawn and
another box inserted with fires heated up to the degree required within
five minutes.
Thirdly. I claim fitting a sight tube about mid-distance and mid- 3

page_text: height along an annealing box containing a fire-place, as and for the
purpose set forth.
In witness whereof, I, the said John Tenwick, have hereunto set
my hand and seal, this Second day of March, One thousand eight
hundred and seventy-six.