Improvements relating to the Heating of Metals by Electricity, and to Machines therefor.
Year: 1891

page_text: COMPLETE SPECIFICATION.
Improvements relating to the Heating of Metals by Electricity,
and to Machines therefor.
We, GEORGE DEXTER BURTON, a citizen of the United States of America,
residing at Boston, in the County of Suffolk and State of Massachusetts, United
States of America, Electrician, Arthur HerbeRT EDDY, a citizen of the
United States of America, residing at Hartford, in the County of Hartford, and
State of Connecticut, Electrician, and GEORGE TIFT BRIGGS, a citizen of the
United States of America, residing at Windsor, in the County of Hartford, and
State of Connecticut, Electrician, do hereby declare the nature of our invention
and in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
Our improvement relates to electrical machines for heating metals preparatory
to shaping, forging, or welding the same in the ordinary manner, by hand or
machine tools, and it consists in certain new and useful constructions and com-
binations of the several parts of the same, and a method of operating and using the
same, substantially as hereinafter described and claimed, whereby we are enabled
to speedily and economically bring long and large bars of metal to a heat suitable
to work or fashion them into the ultimate form desired.
Our construction of mechanism enables us to perform all the valuable heating
effects of the smith's forge without its wastefulness and other disadvantages in
working metals, and it also enables us to do work that could not be well performed
by the aid of a forge.
Heretofore, in attempting to heat metal bars by the direct action of the electric
current, a difficulty has arisen in one of two ways. First, a current of compara-
tively high potential but of low heating power has been tried which, although
capable of being forced through the metal, gave small and comparatively slow
heating effects, and as the heating of the metal progressed and its resistance
proportionately increased it was found, with the then-existing appliances, practi-
cally impossible to control the heat so as to stop it at the right point. For
example, if it was desired to raise iron or steel to a welding heat, when after
a considerable time it was accomplished the heat could not be controlled but ran
much higher. The current generating devices also heated so that continuous
operation was impractical.
On the other hand, when a current of small electromotive force and great volume
was tried, it was found impossible to force it through any considerable length of
iron or steel, or other metals, which it was attempted to raise to a suitable heat
to shape or work it. This was because the amount of current which can be forced
through a metal rod or bar is equal to the potential divided by the rod's resistance,
and when the resistance was increased by lengthening the rod or bar to any great
degree the potential was insufficient to pass any of the heavy heating current
which was generated through the length of the rod or bar. Besides this the
apparatus heated unduly in certain parts because of imperfect arrangement for
conveying the heating current to the rod.
For the above reasons the previous working of metals by the direct action of
electricity has been substantially confined to such operations as electric welding
where a very small length of metal was required to be heated, and it has been
proposed to overcome these difficulties by connecting various parts of the length of
a metal bar to be heated to the electric generating mechanism in multiple arc, so
that the currents shall have very little distance to traverse from one electrode to
the other through the metal.

page_text: D our apparatus hereinafter described, we are enabled to heat metal bars of
any cross section up to 1 inches square and from 12 to 18 inches long within one
and one-half minutes, and to continue to operate the machine in this work day
after day as continuously as an iron heating forge is used. This is accomplished
without undue heating of the electric connections or conduits of the mechanisms,
which would give rise to a loss of electric power.
In the drawings-
Fig. 1 is a plan view of our mechanism with the electric connections and con-
struction diagramically shown.
Fig. 2 is a side view of the conducting rings and clamps removed from the
converter.
Fig. 3 is a front view of the same.
Fig. 4 is an enlarged vertical section through one of the metal holders.
Fig. 5 is an enlarged top plau view of the converter, partly in section to show its
construction and connections more clearly.
Fig. 6 is a vertical section through the core and one of the windings of the
primary coil of the converter enlarged.
Fig. 7 is a perspective view of one of the windings of the secondary coils of the
converter detached therefrom.
Fig. 8 is an enlarged end elevation, partly in section, of the alternating dynamo,
which furnishes the electric current to operate the mechanism.
Fig. 9 is a side elevation of the exciter dynamo, which is used to excite the field
coils of the dynamo shown in Fig. 8.
Fig. 10 is a top plan view of the various mechanisms as they appear in their
casings, with the rheostat located in a different position with relation to the
converter.
Referring to the general plan of the series of mechanisms we use, E, is the
exciter dynamo which is used to excite the field coils of the alternating dynamo, D,
which is in turn connected to the converter, C, which transforms the dynamo
current of high electro motive force into the heavy heating current of low
potential, which is used to heat the metal bar, B, held in the metal hoiders c, c, of
the converter. R is the rheostat to control the heating current, preferably located
alongside of the converter. S is the switch to throw the heating current off or on.
Tis the cut-out.
The method shown of connecting and constructing these various mechanisms is
what gives their superior result which is, as before stated, the heating of the iron
bar B, say of three-fourths of an inch cross section and 18 inches long in the part
heated between the metal holders, to a welding heat in thirty seconds.
The exciter dynamo E has its armature, 1, placed between the poles of its field
magnets 2, 2, and is made to excite its own field and to furnish its current to the
dynamo D.
In order to control the heat with sufficient rapidity and effectively the
rheostat, R, is introduced into the series wound circuit of the field of the exciter
dynamo, and in this position is able to effectively control the heating current in the
bar B with a reasonable size resistance in the rheostat and with a small dial
quickly operated, which control would be quite impossible in either the primary
circuit of the dynamo, D, between it and the converter, C, or in the secondary
circuit passing from the converter through the bar B. A brief consideration of
the relation of these mechanisms will show why this is so. The exciter dynamo E
gives, for example, a working current in its field of one-fifth of 220 volts, which is
the normal current on its circuit leading to the alternating current dynamo D.
Under this excitation of its field magnets the alternating current dynamo D yields,
on its circuit leading to the converter, a current of say 1600 volts. This alter-
nating current is transformed in the converter into a heavy heating current of
great volume and having a potential of from 4 to 7 volts.
It is obvious, therefore, that the rheostat in the exciter field circuit, by reducing
its current one volt will effect a change of 320 volts in the dynamo current, and

page_text: will effect a corresponding change in the volume of the heating current flowing
through the bar B, and it is obvious that the rheostat can regulate the current by
changing it the fraction of a volt in the exciter field circuit where it must change
it many volts in the working circuit of dynamo D, and where it must deal with an
unknown and excessive voluine of current in the secondary circuit of the converter.
It is also obvious that the same effect in lesser degree will occur in endeavoring to
regulate the current by placing the rheostat in the circuit leading from the exciter
to the alternating dynamo, as it requires five times the change in the rheostat to
effect the same result as when located as we have described it.
While, therefore, a simple and ordinary rheostat of proper construction will
delicately and quickly regulate the heating effect of the apparatus, when placed in
the exciter field circuit, it is obvious that it must be much more complicated and
expensive in construction when placed in either the working circuit of the
dynamo D, or the secondary circuit of the converter. Besides this it is found that
if the rheostat be placed in the circuit between the alternating dynamo and the
converter, any attempt to use the rheostat to regulate the current so as to control
the heat in the bar, B, at once interposes such resistance in that circuit as to heat
the rheostat and lower the voltage, so as to arrest the progress of the heat
through the bar B. This is due to the fact that the resistance of the rheostat
causing it to heat varies its resistance. very rapidly beyond the control of the
operator. In other words, it ceases to be a controllable rheostat, and the bar B
requires a higher voltage as it gets hotter in the current from the secondary coil
of the converter instead of a lower voltage, so that the rheostat in the main circuit
operates against the requirements of the machine.
It is also found that the rheostat, when placed in the secondary circuit of the
converter, is utterly incapable of regulating the current of such immense volume
and low potential as our mechanism produces, and we have not as yet dis-
covered any means of making and applying a rheostat which will deal practically
with that current and allow it to produce the heating effects which we have
described.
The circuit 3, of the exciter dynamo, E, leads from the commutator brushes to
the connections 4, 5, of the field of the alternating dynamo. The rheostat, R, is in
a shunt of the circuit leading from the poles of the commutator brushes through
the field coils. The circuit 3, 3, passes from the exciter through the cut-out, T,
and the switch S to the connections 4, 5, to the terminals of the circuit passing
through the field coils of the dynamo D. The necessary screw cups for this
purpose are attached to the frame work of the dynamo D, and are also provided
upon the frame work of the exciter dynamo E, as shown in Figs. 9 and 10.
In the heating and tempering of metals it is necessary to control the heat in the
bar B with great delicacy and rapidity as, for instance when a welding heat is
required, as a higher heat would burn the bar and destroy its welding properties.
Hence the rheostat R is placed within reach of the operator heating the bar in
the converter C, and connected by wire with the shunt of the exciter field coils, as
shown in Fig. 1. The regulation of the current by this means is rendered easy
and instantaneous without interposing any resistance in any of the circuits, which
will counteract or destroy the potential of the current exerted upon the bar B, as
governed by the shifting of the pointer or arm of the rheostat.
6, 6, are the field coils of the alternating dynamo, D, which are in circuit with
the exciter. These coils are alternately wound in opposite directions as shown, so
as to be alternately positive and negative and so as to have the diametrically
opposite coils of the field positive and negative. The armature, 7, of the alter-
nating dynamo D is provided with an equal number of pole pieces or projections to
the field coils, within which it rotates, but only every other one of these armature
pole pieces or projections of its core is wound with a coil of wire; the successive
winding being made in same direction. This feature of having one-half of the
pole pieces of the armature core unwound is considered important, as the

page_text: magnetism is conveyed by the field more freely to the armature core than if all
the pole pieces of the core had currents of electricity passing around them, when
brought opposite to the cores of the field coils, and the result is the production of
pulsations of electricity in the armature coils 8, 8, of the alternating dynamo,
peculiarly adapted to be converted into a current of a different potential in the
converter C, to which these electric currents pass over the electric circuit 9, 9,
which leads from the collecting brushes 10, 10, of the alternating dynamo.
To the terminals 11, 11, of the circuit 9, 9, in the converter, the primary circuit
coils of the converter 12, 12, are connected in series parallel in pairs of two; that
is to say, the coils of each pair are in series with each other and in parallel with
every other pair. These coils 12, 12, of the primary circuit consist of com-
paratively fine wire placed or wound around an annular core, 13, of the converter,
which is of peculiar construction. It consists of sections or segments of uninsulated
wire formed into a ring by laying the wires side by side so that the ends break
joints, and so that while the lines of force generated in the core by the primary
coils 12, 12, flow around the core continuously they are broken up by the
disconnected ends of the wires forming the core, as shown more clearly in Fig. 5.
This augments the inductive action of the core on the secondary coil and accom-
plishes the conversion of the electric current with much less loss of energy than in
other methods heretofore attempted where currents of such low potential and great
volume as we use are required in the secondary coil.
The primary coils 12, 12, are all wound on spools in the same direction around
the core, 13, and between them are placed the secondary coils, 14, which are also
wound around the core and consists of sheets or plates of copper or other suitable
conducting material, so cut or formed that they present themselves edgeways to the
core and their breadth transversely of the core shall be much greater than their
thickness in the direction of the core, or of their exposed faces to the core. These
coils of the secondary conductor 14, are separated by sheets of insulating or non-
conducting material, 15, and have their terminals 16, 17, respectively connected to
the conducting rings 18, 19, which surround the coils and core of the converter.
(Figs. 2, 3 and 7.)
It will thus be seen that the secondary coils are connected to these rings in
parallel or multiple arc, conveying positive electricity to the one and negative
electricity to the other.
From the ring, 18, the arm 20 projects outward carrying on its end a metal-
holder, and from the ring 19 the arm 21 projects outward so that its outer end and
metal-holder is brought parallel with that of the arm 20. Thus when the bar B
is inserted in these arms and clamped in position it completes the secondary circuit.
The clamp is formed of a simple eccentric, 22, having a handle and turning on
pivots journaled in the end of the arm, so as to grip the bar B against a face of the
latter.
The primary coils 12 are of insulated wire and are carefully insulated from the
wires of the core, 13, by a sheet of non-conducting fiber, 23, and the secondary
coils are insulated from the core in the same manner.
By forming the conducting rings, 18, 19, continuous, they not only form a double
conduit for the electricity from the respective terminals of the secondary coils
attached to thein, but they also induce currents of opposite polarity in each other
respectively when the circuit is completed by the insertion of the bar B, and thus
inductively reinforce the current delivered to them by the converter, since the
current will be flowing continuously around each endless ring. It also appears
probable that these continuous endless rings and the continuous aunular core inside
of them act and react on each other by induction, to vary and regulate the
potential of the current delivered through the bar B as it is required to heat the
bar, furnishing a current of lower potential and greater heating power when
the heating of the bar is begun and its resistance is comparatively low to the
passage of the current, and furnishing a current of higher potential as the bar

page_text: becomes heated and its resistance increases and more electric energy is required to
force the current through the bar, and by this alternate weakening and strengthening
of the potential of the secondary current as required, the heating effects are
accomplished until the bar is melted.
These rings may have more than one pair of arms 20, 21, with their attached
metal-holders, such duplicate arms being located on various sides of the converter
rings, so as to permit access thereto of several workmen engaged on different
classes of work which they desire to have heated, and it will be found that such
different classes of work may be carried on with the same converter having different
or separate arms connected thereto, because as bar B in one pair of metal-holders
begins to heat, the increased resistance throws a greater current of electricity into
the work held in the second pair of arms and metal-holders, and heats that, so that
the excess of power required to operate the several pairs of heating metal-holders,
is only slightly in excess of what is required to heat the bar in one pair of
metal-holders when used alone. Such excess required is equivalent to the
small proportions of electric current which is demanded by the bar which first
becomes heated.
This method of successively heating several bars in metal-holders, applied to the
same converter also enables the workman to be performing his forging while several
other pieces of work are successively being heated in a converter having a
multiplicity of pairs of metal-holders, and the workman may thus regulate the
speed at which the successive pieces of work arrive at a forging heat, by introducing
various numbers or sizes of other pieces of work into the other metal-holders of
the converter and carrying on the heating of the same simultaneously.
These several pairs of metal-holders might be attached to a single pair of arms
instead of being on different pairs, and produce similar effects in conducting the
process of working the metals.
The variations in the potential of the secondary circuit correspond with the
greater or less resistance of the iron bar B in the different stages of heating, and
it is also accomplished by a corresponding variation in the potential of the primary
working circuit of the alternating dynamo; that is to say, when the secondary
current of high ampereage is flowing with the greatest ease through the bar B, the
voltage of the working circuit current of the alternating dynamo is reduced, but
when the resistance of the bar B becomes greater, checking the flow of the great
volume of current in the secondary circuit of the converter, the voltage of the
dynamo current increases; the dynamo itself being run at the same speed
continuously through the whole operation.
Referring more particularly to the construction of the converter it will be seen
that the conducting rings 18, 19, are held apart by having their internal projecting
flanges bolted to the terminals respectively of the secondary coil, so that all negative
terminals shall be bolted to one ring and all positive ones to the other, and thus
sustain the rings apart, because the whole strain comes edgeways on the plates
forming the secondary coils 14; also that the secondary coils embrace the core by
intervening insulating material, so as to keep it in position with relation to the
rings; also that the primary coils are wound and supported upon the core by
insulating material.
In the middle of the converter the terminals 11, 11, are supported upon the
wooden block 30, and the series of insulated wires of the primary circuit, which
attach the coils 12, 12, to these terminals, sustain this block 30 in position. Thus
the converter becomes a homogeneous structure, only requiring to have the circuit
wires 9, 9, connected to its terminals to be ready for use.
Although we show and describe in this Specification, the two pairs of arms 20, 21,
attached to the rings 18, 19, of the converter, it is not intended in this application
to claim that specific adjustment of the two pairs of arms but only the connection
of the two pairs of clamps and holding arms broadly, when connected in multiple
are to electrical conduits leading from the converter rings 18, 19.

page_text: Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. The combination of an electric converter for converting electric currents of
high potential into those of low potential by induction, provided with metal-holders
in its secondary circuit arranged to hold therein the article to be heated, an
alternating current dynamo connected to the primary circuit of said converter, an
exciter dynamo connected to the field coils of said first dynamo, and arranged to
energize the field magnets thereof, and a rheostat interposed in the electric
circuit of said exciter dynamo, and adapted to regulate the amount of excitation
of the fields of said first dynamo ; substantially as described.
2. The combination of an electric converter for converting electric currents of
high potential into those of low potential by induction, provided with metal-holders
in its secondary circuit arranged to hold therein the article to be heated, an
alternating dynamo connected to the primary circuit of said converter, an exciter
dynamo connected to the field coils of said first dynamo, arranged to energize the
field magnets thereof and having a shunt circuit from its armature brushes through
its own field coils, and a rheostat interposed in said last-named shunt circuit,
adapted to regulate the excitation of the fields of the exciter dynamo; substantially
.as described.
3. The combination of an electric converter for converting electric currents of
high potential into those of low potential by induction, provided with clamps in
its secondary circuit arranged to hold the article to be heated, an alternating
current dynamo connected to the primary circuit of said converter, an exciter
dynamo connected to the field coils of said first dynamo and arranged to energize
them, and a rheostat located within reach of the operator engaged in heating the
metal in said metal-holders, and connected in the circuit of said exciter dynamo,
and arranged to regulate the current in the same, substantially as described.
4. The combination of an electric converter for converting electric currents of
high potential into those of low potential by induction, provided with metal-holders
in its secondary circuit arranged to hold the article to be heated, and an alternating
current dynamo connected to the primary circuit of said converter, and
constructed with a series of field coils upon its field magnets and with coils upon
every alternate pole of the armature, whereby the latter coils are respectively
located on the opposite side of the armature from poles having no coils,
substantially as described.
5. The combination with a converter for converting electric currents of high
potential into those of low potential by induction, of two pairs of metal-holders,
respectively connected in its secondary circuit and arranged to hold the metal
article to be heated in such manner that its increased resistance under heat will
divert a larger quantity of the electric current through the metal article
simultaneously held in the other pair of clamps, substantially as described.
6. The method of regulating the flow of the electric current from the couverter
through the metal article to be heated thereby, as herein before described, that is to
say, by placing a greater or less number of other metal bars in the several other
pairs of clamps, connected to the secondary circuit in multiple arc, and allowing
them to become more or less heated while regulating the heating of the first
mentioned metal article, substantially as described.
7. In an electric converter for converting electric currents from one potential to
another by induction, for use in metal working, the combination of the primary
circuit coils, 12, the secondary circuit coils, 14, and the annular core 13, formed of
lengths of uninsulated or partially uninsulated wire, arranged side by side and
breaking joints at various intervals in the circuit of the core substantially as
.described.
8. In an electric converter for converting electric currents from a high potential
to a lower potential by induction, for use in metal working, the combination of the

page_text: primary circuit coils, 12, formed of wire of equal diameter in all directions, the
core, 13, and the secondary coils 14, of greater diameter transversely to the core
than in the direction of its length, and disposed around the core between the
primary coils and with their broader faces adjacent thereto, substantially as
described.
9. The combination, in an electric converter for converting electric currents
from one potential to another by induction, of the primary circuit coils 12, the
annular core 13, and the series of secondary, coils, 14, having their positive and
negative terminals respectively connected to curved conductors, 18 and 19,
surrounding said core externally and lying substantially parallel thereto, and
having clamps for holding the work and completing the circuit connected thereto
respectively, substantially as described.
10. The combination, in an electric converter for converting electric currents
from one potential to another by induction, of the primary circuit coils 12, the
annular core 13, and the series of secondary coils 14, having their positive and
negative terminals respectively connected to ring-shaped conductors 18 and 19,
lying substantially parallel to each other and respectively having metal-holders.
for holding the work and completing the circuit connected thereto, substantially
as described.
11. The combination in an electric converter for converting electric currents.
from one potential to another by induction, of the primary circuit coils 12, the
annular core 13, and the series of secondary coils 14, having their positive and
negative terminals respectively connected to ring-shaped conductors 18 and 19,
surrounding said core externally and lying substantially parallel to each other, and
respectively having metal-holders for holding the work and completing the circuit
connected thereto, substantially as described.
12. The combination in an electric converter for converting electric currents
from one potential to another by induction, of the primary circuit coils, 12,
arranged with two coils forming each pair in series and with each series pair in
multiple are in the primary circuit, such coils surrounding the core or some part
thereof, the secondary coils, also surrounding the core and connected in the
secondary circuit in multiple arc, and the terminals of the secondary circuit
provided with metal-holders for holding the work to be heated in the circuit.
13. In an electric converter for converting electric currents from a higher
potential to a lower one by induction, for use in metal working, the combination
of a primary coil or coils of wire in the primary circuit, a core surrounded by the
same, and a series of coils surrounding said core and connected in multiple are to
the secondary circuit, each of said last named coils consisting of a plate of metal
surrounding the core edgeways, or presenting its thin edge thereto, substantially
as described.
14. The combination, in an electric converter for converting electric currents
from a higher potential to a lower one, of the primary circuit coils 12, the core 13,
the secondary coils 14, and the curved conductors 18 and 19, respectively connected
to the terminals of the secondary coils, and respectively carrying the metal
arms 20 and 21 rigidly projecting therefrom and supported thereby, and
provided with metal-holders for holding the bar to be heated, substantially as
described.
15. In an electric converter for converting electric currents from a higher
potential to a lower one by induction, for use in metal working, the combination
of the outer rings 18 and 19, forming positive and negative electrical conductors,
the secondary coils 14, having their terminals respectively attached thereto and
surrounding and sustaining the core, 13, by interposed insulating material and the
insulated primary circuit coils also surrounding and sustained by the core, forming
a complete inductorium, substantially as described.
16. In an electric converter for converting electric currents by induction from
a higher to a lower potential, for use in metal working, the combination of the
annular 'core 13, the primary and secondary coils surrounding the same, and the

page_text: central plate of non-conducting material arranged within the core to receive the
terminals 11 11 of the primary circuit, and the connections thereto of the primary
coils 12, 12, substantially as described.
Dated this 16th day of September 1891.
GEORGE DEXTER BURTON.
Witnesses to signature of G. D. Burton:
CHESTER MARR, Accountant,
Gloucester, Mass.
CHAS. F. ADAMS, Commission Merchant,
GEORGE TIFT BRIGGS.
Witnesses to signature of G. T. Briggs:
ARTHUR D. NEWTON, Secy. and Treas.,
Hartford, Conn.
MILON E. BAIRD, Genl. Agent,
Newton Highlands, Mass.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicants.