An Improved Process for Treating Steel in the Manufacture of Files.
Year: 1894

page_text: Date of Application, 1st Mar., 1894
Complete Specification Left, 28th Nov., 1894-Accepted, 9th Feb., 1895
PROVISIONAL SPECIFICATION.
An Improved Process for Treating Steel in the Manufacture
of Files.
I, JAMES SMILLIE, of Belmont Villas, Chapeltown, in the County of York,
do hereby declare the nature of this invention to be as follows :-
In the manufacture of files for the use of engineers and others, it is important
that the steel of which they are made should be thoroughly and uniformly softened
in order to prepare them for the process of cutting the teeth, and it is found that
a considerable per-centage of the files softened in the ordinary way heretofore used
are wasted and spoiled on account of the uneven and unreliable character of the
softening so effected.
In order to prevent such waste and to obtain the most perfect result, I find that
it is necessary that the steel should be heated to the required temperature without
the possibility of its coming in contact with the solid or gaseous fuel by which the
heat is produced, and by my invention I place the steel which is, to be softened in
suitable chambers as nearly as possible hermetically sealed, and submit the said
chambers to a steady external heat for a sufficient length of time. If the chamber
be then allowed to cool very slowly and gradually, I find that the steel which it
contains is effectually and perfectly softened and can be manufactured by suitable
cutting and hardening into files of the best possible quality without waste.
Where Bessemer steel is used for making files, the percentage of waste is very
much larger than with steel ordinarily used, but by my improved process I am
able to make from it files of excellent quality, without flaw, and with little or
no waste.
I am aware that steel and other metals have been annealed and softened by
heating them in closed chambers or furnaces, and I do not claim broadly such
treatment, but my invention consists in facilitating the manufacture of files, by
softening them in airtight chambers in which they are gradually heated to the
required temperature and are then allowed to cool very slowly, the heating and
cooling being effected without the steel coming in contact with the fuel used.
In order to put my invention in operation upon a large scale, I take a furnace
resembling an ordinary gas retort, having an open end which can be closed by a
moveable airtight door. The steel which is to be softened for the purpose of being
cut to form files is inserted into this furnace, and the door is replaced, the joint
being made as nearly airtight as possible. The furnace is then heated by external
heat until it reaches the required temperature (a good red heat) and the fuel is
then withdrawn and the furnace and its contents allowed to cool very slowly and
gradually. When cold, the door is opened and the steel removed and the latter
then only requires very slight grinding to render it fit for cutting the teeth in the
usual way, files of the best possible quality being thus obtained.
In some cases, I place a small quantity of powdered coke or other carbon in any
suitable vessel in the furnace with the steel, so that the oxygen present in the
air in the furnace is absorbed.
The attainment of the required temperature may be observed by sight, or by a
pyrometer, or other equivalent means. A dull red heat is not sufficient to ensure

page_text: the proper softness for cutting whilst an intense red heat softens the steel but at
the same time destroys it so that it cannot be properly re-hardened.
Dated this 1st day of March 1894.
EDWARDS & Co.,
35, Southampton Buildings, London, Agents for the Applicant.
of Files.
JAMES SMILLIE, Belmont Villas, Chapeltown, Sheffield, Analytical Chemist,
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 process of heating steel for softening, preparatory to cutting for files is as
follows:
The steel is heated in a closed vessel, so as to prevent the heating flames or
gases coming into contact with the steel; also the placing of some powdered coke
charcoal or carbon of any kind in any earthenware or iron dish, alongside of the
steel, but not in direct contact with it, for the carbon to combine with the oxygen
of the enclosed air, or any air or gases which might enter, to produce a non-
oxidizing atmosphere.
The accompanying plans will show the furnace, an iron retort which can be
filled with steel for files, from points marked A to B, and in the front of the retort
from B to C, an earthenware or any kind of a flat iron dish, filled with powdered
coke, charcoal, or carbon in any form, and in addition in any other part of the
retort, in any vessel, which will prevent it coming into direct contact with the
steel, so as to take up the oxygen of the enclosed air, or any air or gases which
might.enter.
Then the door of the retort sealed up with mortar, or any likely substance to
render it practically air tight, and the retort heated by means of a fire under it,
marked D, or by using gas in any way.
A sight hole is left open in the door to allow of any moisture &c. escaping on
first applying heat, and when the retort is warmed a little, the sight hole to be
plugged up with a little fireclay, which can be easily removed any time to allow
for examination, as to the progress of the heating, and then again plugged up.
When the steel becomes hot enough, which can be judged by sight, or by means
of a pyrometer, the sight hole is made air tight, the fire withdrawn, the damper
inserted in chimney, the front of the fireplace blocked up, and the retort allowed
to cool slowly.
"
Different sizes of retorts can be used for files of different dimensions.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed I declare that what I
claim is,
1. That steel to be used in the manufacture of files, preparatory to cutting, by
this process, be heated in a closed vessel, to prevent the heating gases coming
into contact with the steel.
2. By placing coke, charcoal &c. in the vessel alongside of but not touching the
steel, to form a non-oxidizing atmosphere as hereinbefore described.
Dated this 27th day of November 1894.
JAMES SMILLIE.