Improvements relating to the Annealing of Metals.
Year: 1890

page_text: COMPLETE DIMUIFICATION,
[Communicated from abroad by THE RUSSELL AND ERWIN MANUFACTURING COMPANY,
of New Britain, Connecticut, United States of America.]
Improvements relating to the Annealing of Metals.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake, and Co., Patent Agents,
Southampton Buildings, in the County of Middlesex, do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
This invention relates to the annealing of metal, and the chief object thereof is to
effect economy in the use of the gas and fuel.
It is well known that if iron while being annealed is subjected to the action of
ordinary illuminating gas or equivalent gases, oxidation is prevented; but this know-
ledge is theoretical, that is to say, it is confined to descriptions in patent specifi-
cations and other publications, instead of being in practical use. My improved
process is, so far as I am aware, the only process which has ever been successfully and
continuously worked in a practical manner. In the processes of annealing heretofore
adopted, the metal has been heated in chambers which, during the greater part of the
heating process, were sealed as tightly as possible, or else a continual flow of gas has
been passed through the vessel. The first method is objectionable for. the following
reasons, viz. a very strong vessel is required to prevent explosion, and, even with
the greatest care, some leakage is likely to occur and therefore when the gas contracts
in cooling, air is admitted which causes oxidation. The second method is objec-
tionable especially in localities where gas is expensive, on account of the waste of gas
caused by the continuous flow. It will, therefore, be seen that the action of gas on
iron in annealing is well-known and that my invention is in the nature of a mechanical
process, that is to say, of a succession of mechanical steps or stages in the treatment
of the metal.
In the accompanying drawings I have illustrated by a single figure, partly in vertical
section and partly in elevation, an apparatus which may be used in the practice of
my invention.
My process is particularly applicable to annealing wrought iron, homogeneous iron
or steel of the kind and composition ordinarily in the market, but I do not limit myself
any specific metal.
to
A is a gas-cock which is attached to a pipe leading from the main source of supply,
as for instance the city gas-works or other suitable reservoir that will maintain
practically a uniform pressure during the heating and cooling processes. B is a
chamber or vessel which, in the apparatus shown, is filled with coils of wire a to be
annealed, and which is closed by a cover b so as to make it practically gas-tight, c is
a passage or pipe which extends through the cover to near the bottom of the vessel
and is closed by the cock h, and d, d are handles for convenience in lifting the
vessel. e is a section of pipe which opens into the vessel B at one end, its other
end being connected by a flexible pipe C with the reservoir. I also provide a small
gas burner having a cock g and preferably situated near the cock A.
I prefer to employ a portable vessel so that it may be filled with the metals to be
treated and closed or sealed before the vessel is placed in the heating furnace. The ..
vent port is opened as for instance by opening the stop-cock h in the pipe c and gas
is admitted to the vessel B through the stop-cock A. The gas is allowed to flow
Whether or not
until the air is wholly expelled from the vessel B through the vent.
the air is so expelled can be tested by applying fire to the vent and noticing whether
or not the gas burns steadily. When all the air is expelled the stop-cock h is closed
to seal the vessel as tightly as possible, the vessel being still connected with the;.gas

page_text: reservoir and under the pressure of the gas therein, in which condition it is placed
within a suitable heating furnace and brought up to a red heat. As the gas expands
in heating, the excess in volume is pressed back into the reservoir; but the gas
within the vessel is maintained under the same pressure as that in the reservoir so
as to ensure the keeping, of the. vessel filled with, gas under a practically uniform
pressure. After the desired heat has been imparted to the metal within the vessel for
a sufficient length of time,as. in. ordinary annealing, the said vessel, is removed from
the furnace by means of any suitable hoisting apparatus and is allowed to cool.
Other vessels should be previously filled for replenishing the furnace as soon as the
first vessel or vessels is or are removed so that there may be no waste of fuel or
time. While the removed vessels are cooling and the gas therein contracts the
contraction is compensated for by the pressure from the reservoir, thereby, keeping the
vessel B filled with gas during the entire operation until the metal is thoroughly.
cooled whereby all:oxidation is prevented and without an unnecessary, waste, of gas.
There may at times be some slight leakage from the vessel, but this will do no harm
with the exception of waste, as the gas will be immediately burned, when it escapes.
Such escape of gas is, however. not intentional, as. I design in all cases, to, make
all parts of the vessel and its connections as tight as is practicable.
The advantage of utilizing the pressure in the gas main, or gas, reservoir to provide
for expansion and contraction of the gas within the vessel, B may, be attained by the
use of a vessel permanently. located within, the furnace,, and, connected with, the
reservoir either by a flexible or rigid, connection, but such an arrangement does not
accomplish the economy, in time, and fuel that is accomplished with. the, use, of. a
portable vessel...
So much of the process.or method as I have herein, described, is complete, in itself
for a useful purpose; a still further, saving, of gas may, however, be effected by adding
another step to the process above described.
In cases where there. is considerable space for gast within the vessel, as, for instance
when the work or, articles placed within the. chamber do not fill the vessel, I make a
saving in gastby-forcing, the gas, that remains, in the vessel, after cooling, back into
the reservoir. This may be done by attaching, to the pipe c a pipe for the introduction
of compressed air either by means of a pump or otherwise, whereby the, gas which
remains in the vessel and pipes may be forced back through, the pipes e, C, and. through
the stop-cock Ainto the reservoir. In order to, determine when all or nearly all the
gas is thus forced back, I provide the small burner f, the cock leading to, which,may,
be opened about the time the gas. is, expected to be thus forced, out. By applying a
light to the burner, and watching the color of the, flame one, can readily, detect; the
pressure of air in the flame which shows that the gas is nearly all forced out of the
pipe C and that it is time to close the cock A and discontinue, the admission of com-
pressed air. The vessel can then be opened, for re-loading without any material, waste
of gas. After a few, trials with, a given, vessel filled with a given article,, the
approximate time required for, forcing the gas from the. vessel and consequently the
time to light the burner foan, easily be determined. If the burner is. a small one,
there would be.but little waste of gas if it was lighted. long, before all the gas, was
expelled:
Having now particularly, described and ascertained the nature of the said invention,
and in what manner the same is, to be performed as communicated to me by my
foreign Correspondents, I, wish it understood that I claim:
First: The herein described method, of annealing, metals, consisting in heating, the
metal and allowing it to cool-under pressure of a non-oxydizing gas, which pressure
is maintained during the heating and cooling operations within the closed, annealing
chamber by an open connection with the gas.supply, allowing free movement of the
said gas to and from the gas supply, for the purpose specified..
Second. The-herein described method of annealing metal, consisting in placing the
metal in a suitable vessel, expelling the aire therefrom, by the introduction of gas, then

page_text: closing the vent and placing the vessel and its contents in a furnace where it is
subjected to heat, then removing the vessel with its contents from the furnace to cool
and maintaining throughout the heating and cooling a constant pressure of gas within
the vessel, for the purpose specified.
Dated this 12th dow of Mo 1900
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.