Improvements relating to the Forging of Metals for Making Steel and Iron Tools.
Year: 1892

page_text: Date of Application, 17th May, 1892-Accepted, 9th July, 1892
COMPLETE SPECIFICATION.
Improvements relating to the Forging of Metals for Making Steel
and Iron Tools.
I, GEORGE DEXTER BURTON, a citizen of the United States of America,
residing at 194 Washington Street, Boston, in the County of Suffolk and State of
Massachusetts, United States of America, Electrician, do hereby declare the
nature of my 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 methods of making tools, or parts thereof, of steel and
iron, and it consists in certain new and useful steps and processes relating thereto,
substantially as hereinafter described and claimed.
The drawings show certain mechanisms, by which my invention is carried into
effect as follows:-
:-
Fig. 1 is a top plan view of an electric current converter, and a side elevation of
the dynamo for heating the steel or iron.
Fig. 2 is a side elevation of the converter.
Fig. 3 is a front elevation of the same.
Figs. 4, 5 and 6 are enlarged detail views of one of the clamps, which secure
the iron
or steel in electric circuit while being heated, detached from its
supporting arm.
It has long been well known that in the process of drawing or rolling steel and
iron out into bars and sheets, their immediate surface was condensed and rendered
very homogeneous and capable of receiving a high polish, and retaining it against
rust and wear. In the case of cutting blades formed out of such rolled or drawn
steel, it has also been found that when the extreme cutting edge was formed of the
lamination of condensed metal lying on the immediate surface, it possessed a
superior smoothness and keenness. The process of forging such rolled or drawn
metal bars into tools and utensils of various kinds has always, heretofore, removed
this lamination of condensed metal, due to the rolling or drawing process, from its
surface, first and chiefly, in the form of scale burned off by the fire, and secondly,
by its being crushed or forced into the mass of metal underlying it on account of
the forging heat being applied to the exterior of the sheet or bar and rendering
that the softest. The hammering and pressing of the metal in dies, therefore,.
crushed and moved the more plastic molecules of metal on the surface away from
their contiguity and arrangement with relation to each other, which they assumed
in the drawing process, and broke these up.
My invention has for its object to avoid these disadvantages, and impart
to irregular-shaped forged tools and utensils, or parts thereof, the original
condensed lamination of metal which formed the surface of the rolled or drawn
sheet, from which they were forged. I accomplish this by heating the internal
part of the bar or sheet to a much higher degree of heat than its outer surface, and
to such a degree of heat that the forging may be accomplished by merely bending
around the exterior lamination of the metal to conform to the irregular-shaped
exterior of the part of the finished tool or instrument which it becomes a portion of.
This is accomplished by keeping the exterior cool enough, with relation to the
more plastic interior of the metal, to enable it to hold its original condensed
laminated character, while the tool or instrument is being shaped to the desired
form under the die or hammer, and is also accomplished by the heating being
performed without the application of any combustible or heating agent to the
exterior of the bar or sheet being forged. Unless these two conditions are
observed the invention cannot be successfully practised.
To carry out these purposes I heat the bar or sheet of metal to be forged by an

page_text: electric current in the open air, or in some surrounding medium, which will keep
its exterior surface much cooler than its internal substance, and I am careful not
to raise the heat so high as to destroy the character of this surface, which was
given to it in rolling or drawing the bar. I have discovered that it is possible to
do this, while also raising the heat of the internal substance of the bar to a degree
which allows it to be forged,. and further that the less heat of the laminated surface
enables it to retain its character during the forging process and to conform to the
exterior shape of the irregular tool or implement, or part thereof forged; it not
being burned off in the forge by the combustion applied to it and the electrical
beating process being so speedy that it has not time to oxidize away while being
brought to the required heat.
I will now describe one form of the apparatus which may be employed to carry
out my invention, although other forms may be used. A is a dynamo of any
approved construction, connected by the wires a', a, to the primary coil of the
condenser C. A, is a small dynamo properly connected to the coils of the
dynamo A, as an exciter to energize the current of the latter. A rheostat or
electric regulator, a,
is introduced into the circuit of the exciter having the
swinging arm, a³, by which the strength of the exciter current may be regulated.
The secondary coil of the condenser terminates in the conductor arms c, c², of
great area in cross section to accommodate the heavy current of low electro motive
force, which is delivered through them. The condenser is of any construction
suitable to transform the high tension alternating current of the dynamo into the
heavy current of its secondary coil.
On the ends of the arms c, c², are attached two metal clamps. ¹, d². These are
formed respectively by the cam roller, d³, which is mounted on and pivots in the
casing, d, in such a position with relation to the end of the arm c¹, (or c²,) that
by revolving it, when any object is placed between them, it will squeeze that object
forcibly against the arm. The arm and roller at this point are preferably made of
or faced with copper. The roller is also provided with a handle, d, by which to
revolve it. The clamps d', d², are made with area enough to their faces, which
grasp the bar to be heated to prevent undue heating of the latter where they take
hold of its surface. This is very important, for if the area of conductivity of
these clamps be too small the bar will be heated the highest on the surface where
they grasp it.
The bar to be heated is placed in the clamps c', c², and they are closed. down
upon it and the current turned on. The size of this bar is such, (say one inch wide
and one-fourth inch thick) with relation to the conductivity of the secondary coil
and the arms c¹, c², that it presents a comparatively high resistance to the current
passing through it, and thus becomes rapidly heated to a forging heat, in its
internal substance. The external surface of the bar being exposed to the air
remains at a much lower temperature and preserves. its essential homogeneous
character. While the bar is in this condition I remove it from the clamps d, &,
and subject it to the forging process in a die,. so constructed as to not break the
external shell by repeated blows but merely to compress or bend it into the
exterior form of the article, or part thereof, being forged. I may do this by a die
in a press, or by one mounted in a drop-hammer heavy enough to compress.. the
article into the desired shape under its blows. The movements of the excess of
metal being forged will be found to be chiefly at the more plastic centre of the
heated bar or strip, and only a bending movement on its surface, because the hotter
and more plastic metal at the centre yields more easily.
In this way tools such as table-knives, chisels, augurs &c., may be forged up
either on the blade part or the handle part, or on both blade and handle. parts,.so as
to have upon them the smoothness and polish and homogeneous surface that was
originally formed upon the surface of the bars or sheets of metal, from which they
were forged. I am thus enabled to impart a superior finish to the surface of. such
tools and render them capable of resisting rust and wear in a superior degree, and
where the extreme cutting edge can be formed of this surface part of the metal, as

page_text: in the case of chisels, it has a superior smoothness and keenness. The handles of
such forged tools can also be finished by polishing or nickel plating, with a trifling
expense compared with the present methods.
In heating the metal by the electric current as described, it should be
remembered that as the exterior of the bar or sheet is kept cooler than the
internal parts, the color of the heated surface will indicate a much lower
temperature when the metal is ready to forge than with the methods of forging
now employed, but while this color cannot be readily described in words it will be
easily understood by the expert forge operator, by a little practice.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is :-
The method of making a metal forging which consists in subjecting a rolled or
drawn bar or sheet to be forged to the action of an electric heating current until
its interior is raised to a plastic forging heat and maintaining the temperature of
its exterior so far below that of the interior as to preserve its form and homo-
geneous character, said heating operation being performed within a period which
will avoid the destruction of the external skin of the metal by oxidation, and then
forging or shaping the bar or sheet into the desired irregular shape or article by
bending or shaping the external skin of the bar over the internal plastic metal to
form the surface of the finished article or forged part thereof without breaking or
destroying said skin, substantially as set forth.
11
GEORGE DEXTER BURTON.
Witnesses:
CHAS. F. HOAMS, Merchant, Boston, Mass., U.S.A.
ETTIE F. PHILIPSON, Stenographer, Boston, Mass., U.S.A.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.