Improvements in or relating to Welding or Working Metals Electrically.
Year: 1892

page_text: COMPLETE SPECIFICATION.
Improvements in or relating to Welding or Working Metals
Electrically.
A communication by CHARLES L. COFFIN, of 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, & 6 Bank Street, Man-
chester 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 method of welding or working metals
electrically, hereinafter fully described and claimed.
The figures are diagrams illustrating the invention, in which :-
Figures 2 and 5 are plans:
Figure 1 a cross section on line x-x, Figure 2:
Figures 3 and 4 sections on lines a a and b b, Figure 2: and
Figure 6 a perspective view.
In welding or working sheet metal, it is sometimes necessary to operate upon
sheets which are of different thicknesses in different parts. For instance, the
sheet M, as shown in Figures 1 and 6, is thicker at one side than at the other.
In operating upon material of this kind with a plurality of arcs (which forms the
subject matter of another application filed by the inventor contemporaneously with
this one No. 17227 dated September 27th 1892) it is quite desirable to graduate the
size and heating effect of the several arcs so that, while the thicker part of the
metal is being sufficiently heated, the thinner part will not be destroyed, or
To do this, the size of the arc is proportioned according to the cross
section of the material at the different points which are subjected to the action of
vice versa.
the arcs.
The mode of welding herein illustrated is that in which the metal is subjected
to the action of an arc sprung between two extraneous conductors, but it is equally
applicable to that process in which the arc is sprung between the material and one
extraneous conductor.
M represents the material to be heated and welded, and S represents the line
along which the material is to be heated.
The pairs of carbons are represented by the Figures 1 1, 2 2¹, and so on up to
10, 10', their numbers being equal to the number of arcs required.
At the thick part of the material, for instance at the left hand in Figures 2
and 5, larger carbons are used, as shown at 1, 1, than are used at the thin part of the
material, as, for instance, 9 9, Figure 2, or 10, 10, Figures 5 and 6. In some cases,
my correspondent puts the arcs nearer together where the material is thick than
where it is thin, as indicated in Figure 5. In this manner, by using a sufficient
number of arcs, the whole length of the seam to be welded may not only be heated
at once, but may be heated in proportion to its cross section, so as to heat each
part alike, which cannot be done, so far as he is aware, by any system of heating
by fuel.
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 :-
The herein described method of electrically heating metal of varying cross-section
consisting in simultaneously subjecting the metal at different points to the action of

page_text: separate voltaic arcs, whose heating power varies in approximate proportion to
the respective cross-sections of the material at the points to which the arcs are
applied.
Dated this 26th day of September 1892.
WM. P. THOMPSON & Co.,
Agents for the Applicant.