Improvements in Electric Welding.
Year: 1890

page_text: Date of Application (in United Kingdom), 22nd May, 1890
Complete Specification Left, 22nd May, 1890-Accepted, 2nd Aug., 1890
COMPLETE SPECIFICATION..
Improvements in Electric Welding.
I, CHARLES LEWIS COFFIN of Detroit, County of Wayne, State of Michigan, United
States of America, 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 :-
My invention relates to a method of electric welding especially applicable to
welding together the ends of hoops or similar articles by passing a heating-current
through the joint, where the natural tendency of the current is to traverse the article
itself instead of the joint.
The drawings illustrate mechanism by which my invention may be practised:
Figure 1 is a plan view, and
Figure 2 a side elevation.
C represents a block adapted to be secured to a suitable foundation, having rigidly
fixed thereon a clamp D, and having a movable clamp E, sliding in a dovetail
groove J in the block C, a screw-shaft F, threaded into said block C, and provided
with a handle furnishing means for moving a movable clamp E. The clamps D
and E are insulated from said block by a strip of insulating material i.
G represents an electrical conductor, which connects the clamp D with one pole of
a generator of electricity, and H represents an electrical conductor, which connects
the clamp E with the other pole of said generator.
A represents a hoop held in the clamps D and E in position to weld together its
two ends. When the ends of A are brought into contact and the current is turned
on, if supposed to enter through conductor D, connecting with a positive pole of a
generator, the resistance at the joint where the weld is to be made is usually greater
than the resistance of the hoop itself, owing to imperfect contact at the joint, or the
ends not being in contact when the heating is done by springing a voltaic are between
the ends. The current will therefore traverse the hoop A from clamp D to clamp E,
as indicated by the arrows, unless some means be provided to render the resistance of
the hoop greater than the resistance of the joint.
In an Application which I have already filed, I have provided for doing this by
magnetic influence. In this Application I do the same thing by another means.
B represents a gas-jet adapted to throw a flame against hoop A at the joint in the
continuous part of said hoop between clamps D and E. The object of this is to heat
a portion of the hoop A, and thus to increase the resistance of that portion of said hoop
until the resistance of the hoop itself becomes greater than the resistance at the joint,
and the current, entering through conductor G, finds its easiest path across the joint
instead of around through the hoop, in which condition of affairs the current will traverse
the joint, and thereby raise the ends of the hoop to a welding heat, instead of being
short-circuited around the hoop A. When the ends are brought to a welding-heat, the
weld is made by forcing the ends together by means of the inovable clamp E, and the
weld may be then finished in any known way, as by rolling, hammering, etcetera.

page_text: 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 :
--
The herein-described method of welding by electricity an article which furnishes a
path for the current of less resistance than through the proposed joint, consisting in
heating a portion of said article until its resistance becomes greater than that of the
joint, traversing the joint by an electric current, and pressing the ends together to
form the weld.
Dated this Q1st dor of Man 1000
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.