Improvements in and connected with the Method of and Apparatus for Annealing Metallic Wires.
Year: 1893

page_text: Date of Application, 28th Sept., 1893-Accepted, 28th Oct., 1893
COMPLETE SPECIFICATION.
Improvements in and connected with the Method of and Apparatus
for Annealing Metallic Wires.
JOSEPH MOSELEY, of The Chapelfield Works, Ardwick Manchester in the
County of Lancaster, Manufacturer, 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 a process for electrically annealing metallic wires and
to apparatus employed therefor, the objects sought to be obtained being to
prevent oxidation, to obtain a uniform result, and to avoid losses in the heating
effect.
According to this invention I heat the wires to be annealed by means of a current
of electricity passed through them, and quench or cool them in a suitable bath at
the instant that they attain the degree of heat required. During the heating of
the wires they are suitably protected from access of air or other sources of oxygen,
and this protection is preferably continued until the point of immersion in the bath
is reached.
For this purpose, I arrange to lead the wire into the bath, whilst the current is
still passing through it, through a sufficiently enclosed space chamber or passage
into which free access of air is prevented and which may be constructed of or
contain some suitable non-conductor of heat. The wire is caused to traverse the
enclosed space so long as the current is passing through it, and the extent of the
annealing may be governed by. the speed of travel, by the density of current, or by
both combined.
I may carry out my invention in various ways and by various means, but that
which I have hitherto found to be best I will now describe by the aid of the
accompanying diagram and by way of example.
A tube, preferably of glass, may be employed to enclose the wire before its
passage into the bath whilst the current is passing through it. As indicated by the
diagram, A is the annealing bath contained in a suitable tank or vessel B, and
C is the glass tube.
The precise dimensions of the tube are not of great moment provided it be of
sufficient diameter to prevent its being cracked by the heat of the wire and to
prevent possibility of constant contact, and of sufficient length to enclose the whole
of the highly heated part of the wire. For fine wires a diameter of about one
centimeter and a length of about twenty five centimeters will suffice. For thicker
wires, larger tubes should be used.
The wire is led through this tube into the bath at a constant speed determined
by the density of the current and the degree of hardness softness or annealing
desired.
•
The principal advantage attending the use of a glass tube is that it permits
constant optical observation of the temperature colour of the wire. It is not
necessary to close either end of the tube, as, if the tube be of sufficient length the
air will be sufficiently excluded in practice, especially if the lower end of the tube
be immersed in the bath as is in all cases preferred. Should any considerable
distance exist between the end of the tube and the bath, not only may the wire
become oxidised but in some cases actually burnt through. If the end of the
tube be actually immersed in the bath, the best condition exists, because the
wire enters the bath at the maximum temperature attained by it and there is
no loss of heat by needless exposure nor is there any oxidation produced on its
surface.
In substitution for the tube there may be used any
enclosed
space
filled with

page_text: suitable inert gas or material. Alternatively, the wire may be similarly passed
through a hole formed in a mass or block of heat resisting material or so in any
case that that the air cannot act freely on the wire just before it passes into
the bath.
Below the tube C there is arranged in the bath'a guide pulley D, and above the
tube a second guide pulley. E. At the opposite end of the bath there may be a
third guide pulley F, over which the wire may be drawn out of the bath. All
these guide pulleys are grooved and should be of such a diameter that the wire is
not permanently curved by passing around them. The wire passes over the pulley E,
down through the tube, under the pulley D, and over F.
W indicates the wire which is supposed to be operated on. The current should
be led into the wire before it reaches the upper end of the tube C, and this may
be conveniently done by connecting the metallic pulley E to one of the poles of a
dynamo or battery, and ensuring perfect contact with the wire by means of wire
brushes or the like. The current may générally be led out of the wire from the
metallic pulley D, and the density of the current and the speed of the wire may
be so regulated that almost any desired degree of softness or hardness may be
obtained. If desired however, the current may be led out of the wire from the
metallic pulley F, or by means of brushes or rubbers at any point such as from the
adjustable pulley G, between D and F.
Between the source of current and the point at which the contact is made with
the wire W, there should be intercalated in the circuit a set of variable resistances
by means of which the density of current in the wire may be controlled.
Although I have indicated the apparatus in the diagram and have herein described
it as having only one wire passing through it at the same time, it will be obvious
that a greater number may be so passed simultaneously and separately.
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. The method of annealing métallic wires which consists essentially in conveying
the wire continuously through an enclosed space from which oxygen in practically
excluded and thence through a bath, the wire during its passage through the enclosed
space being heated to the required degree by an electric current passing through it,
substantially as herein before described.
2. In the process of annealing metallic wires set forth in the preceding claiming
clause, passing a current of electricity through the wires during their passage
through an enclosed space from which oxygen and sources of oxygen is or are
practically excluded, substantially as and for the purpose herein before described.
3. In the process of annealing metallic wires set forth in the first claiming clause,
constituting the enclosed space by means of a glass' or similar tube, 'substantially
as and for the purpose hereinbefore described.
4. An apparatus for annealing metallic wires, constructed arranged and operated
substantially as hereinbefore described and as illustrated by the accompanying
diagram.
Dated this 27th day of September A.D. 1893.
WILLIAM E. HEYS,
Agent for the Applicant.