Improved Apparatus for Heating Metals Electrically.
Year: 1893

page_text: COMPLETE SPECIFICATION.
Improved Apparatus for Heating Metals Electrically.
A communication by CHARLES LEWIS COFFIN, of 980, Jefferson Avenue,
Detroit, in the County of Wayne and State of Michigan, United States of
America, Chemist.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E. of The Agency for
Foreign Patent Solicitors, 6 Lord Street, Liverpool, and 6 Bank Street,
Manchester, both in the County of Lancaster, and 323 High Holborn in the
County of Middlesex, Civil Engineer, 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:—
The invention consists in an improved apparatus for heating metals electrically,
hereinafter fully described and claimed.
The drawing is an elevation, with the electrode partially in section.
In heating metal by that method in which a voltaic arc is sprung between the
metal and an extraneous conductor, both being in circuit, it is desirable to increase
the area affected by the arc by causing it to rotate or reciprocate, and it has been
proposed to do this by mechanically moving the conductor or by a moving magnet.
My correspondent has discovered that the arc can be caused to rotate by using an
annular conductor and a stationary magnet.
A, represents metal to be heated, and C, represents a hollow, annular conductor,
preferably of carbon, which may be provided with a clamp or holder B, having an
insulating handle H, by which conductor C can be operated.
Metal A and conductor C are connected by conductors x and y with the terminals
of a generator of electricity G.
Drepresents a electro-magnet whose core is preferably made hollow to slip over
conductor C. Magnet D may be supported in any suitable manner, the mode shown
being to provide it with flanges II of insulating material, in which is secured a screw
bolt E passing through a lug or clamp B and provided with a thumb screw F.
This arrangement permits adjustment of the magnet, but it may be varied, or any
other mode of securing the magnet may be adapted.
The coil of electro-magnet D is connected by conductors r¹ and y' with
conductors and y the circuit ¹ and y' being of higher resistance than
conductors and y.
R is a resistance switch of any known construction interposed in the magnet
circuit, and may be used or not, at will.
Electro-magnet D may be placed below metal A instead of on conductor C. If,
however, A is a magnetic metal, magnet C operates better in the position shown,
but with diamagnetic metal it is immaterial whether the magnet is above or below
the metal.
On passing a current through conductors x and y and springing a voltaic arc
between metal A and conductor C, and energising magnet D by an electric current,
the magnet causes the arc to rotate around the end of conductor C, thus covering
an area of metal A equal to, or somewhat greater than, the area of conductor C.
The rapidity of rotation of the arc depends upon the strength of magnet D, and
may be increased by increasing the strength of said magnet, or bringing the magnet
nearer the arc, and decreased by doing the contrary. D may be a permanent
magnet.
The upper end of conductor C may be closed by a stopper to prevent draughts
3 thmuch said conductor

page_text: D may have a core, or it may not; in the latter case it might be more properly
'called solenoid, which is a form of electro-magnet, and is, for the purposes
described, the equivalent of an electro-magnet.
It is believed that the rotation of the arc is caused in the following way-
The electric arc obeys the laws of Ampère in precisely the same manner as au
ordinary electric current; that is to say, it is attracted or repelled by electric or
magnetic currents passing through metallic conductors in various directions. The
arc can be made to revolve around an axis under the influence of a magnet or
solenoid, the arc revolving in the direction corresponding to that of the current
passing through the coil of the magnet or solenoid.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondent, I declare that what I claim is :-
1. In an apparatus for electrically heating metal by means of the voltaic arc,
the combination with a hollow conductor of a stationary magnet for directing and
rotating the arc, the arc being sprung between the conductor and the material,
substantially as shown and described.
2. In an apparatus for heating metal by means of the electric
arc,
the combina-
tion of the metal, a hollow conductor, a magnet for rotating the arc and means for
connecting said metal and conductor with the terminals of a source of electric
energy, substantially as shown and described.
3. In an apparatus for heating and welding by means of the electric arc, the
combination with a hollow electrode of a magnet for rotating the arc and a variable
resistance in circuit with said magnet.
Dated this 11th day of December 1893.
WM. P. THOMPSON & Co,
Agents for the Applicant.