Process of Oxidising and Finishing Sheet Iron or Steel Plates.
Year: 1898

page_text: Date of Application, 23rd May, 1898-Accepted, 30th July, 1898
COMPLETE SPECIFICATION.
Process of Oxidising and Finishing Sheet Iron or Steel Plates.
I, WILLIAM MILTON THEOBALD, Superintendent, residing at Wellsville, in the
County of Columbiana, and State of Ohio, United States of America, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:-
My invention relates to a novel process of producing blued and polished sheet-
iron and steel plates or sheets with an oxidized finish, and the object is to produce
an article of this class in a simple, expeditious and inexpensive manner, and to
these ends the invention consists in the process hereinafter more fully set forth and
particularly pointed out in the claim.
In carrying out my process, I first take a series of sheet-iron or steel plates or
sheets, that may have an oxidized, de-oxidized or acid-cleaned surface, and pile
them up, one on top of the other, upon an annealing bottom or pan, and then
cover the pile with an annealing box.
I then lute or sand all the joints between the box and its bottom, to prevent
the access of air to the plates and thereby prevent undue or excessive oxidization.
In this condition, the plates are introduced into a suitable furnace, close the door,
and, after firing the furnace, subject the box and pan containing the plates to an
annealing heat for about six hours, more or less, which will have the effect of
bringing the plates to the desired or ordinary annealing temperature.
Having obtained the desired degree of heat, the annealing box or pan and its
contents are now withdrawn from the furnace and allowed to cool for about
twenty-five minutes, more or less, or until the temperature inside of the box has
been reduced to somewhere between 900 and 1400 degrees Fahrenheit.
After the plates have cooled to the proper degree, the cover
or box is now
removed from the pan or bottom and the plates or sheets exposed to the atmosphere
until the proper coating of oxide has been attained. The plates or sheets are now
protected from further contact with the air, which may be very simply and
effectually accomplished by laying them horizontally one on top of the other, so
as to exclude the air:
The sheets or plates now have a temperature of from 300° to 900° F. and are
then immediately passed, one or more at a time, between smooth or highly polished
rolls, and, on being rolled at the above temperature, obtain a lustre and polish
and practically uniform degree of color, which they retain indefinitely, by reason
of the oxide coating becoming firmly attached to the surface of the sheets or
plates.
"
This part of the process I term warm rolling" and, to obtain a still higher
degree of lustre or polish and a uniformity of color, the entire process or a part
of it may be repeated.
Due caution must be observed in the process to prevent undue or excessive
oxidization, and for this purpose the non-oxidizing gas may be admitted to the
annealing pan or box to expel the air while the plates or sheets are in or out of

page_text: Having now particularly described and ascertained the nature of my inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:-
The process herein described, of preparing metal sheets or plates which consists
in subjecting said plates to an annealing degree of heat for about six hours
without contact with atmospheric air, then cooling the plates under the same
conditions for about twenty-five minutes to a temperature of from 900° F.
to 1400° F., then exposing said plates to the atmosphere until they have attained
the proper degree of oxidization, and, finally, passing said oxidized plates between
polished rolls at a temperature of from about 300 to 900 degrees, F., substantially
as and for the purpose set forth.
Dated this 21st day of May 1898
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.