Improvements in Mechanism for Converting Electric Currents and in the Method of Applying the same to the Working of Metals.
Year: 1892

page_text: COMPLETE SPECIFICATION.
Improvements in Mechanism for Converting Electric Currents and in
the Method of Applying the same to the Working of Metals.
I, 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, 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 the following statement:-
My invention relates to that class of mechanism known as converters, for con-
verting electrical currents from one potential to another, and for applying the current
from them to the heating of metals, whether such heating be for the purpose of
forging, welding, or soldering, and it consists in certain new and useful constructions
and combinations of the several parts of the mechanism and in the method of
applying the electrical current therefrom to the work to be performed, substantially
as hereinafter described and claimed.
In the drawings
Fig. 1 represents a front elevation of my improved converter, with the outer
casing shown in section to more clearly exhibit the internal construction.
Fig. 2 is a side elevation of a portion of Fig. 1.
Fig. 3 shows the two parts of the converter separated from each other and the
casing removed, and exhibited in top plan view so as to clearly show the method in
which they are constructed and connected to the source of primary supply.
Figs. 4 and 5 are detail views of the switch or cut-out, which is used for regulating
the application of the secondary current of the converter to the work to be done.
A is the outer casing of the converter, which may be made of wood, sheet-metal,
or any other suitable material. Within this casing is located my compound con-
verter, which consists of two single converters combined together substantially as
hereinafter described. The upper single converter is composed of the outer con-
ducting rings, B, B'. To the ring B₁, are attached the positive terminals 1, 1, of
the secondary coils 2, 2, while the negative terminals 3, 3, of the same coils are
attached to the conducting ring B. These attachments are made by bolting the
ends of the copper plates, of which these coils are composed, to ears on the inside
periphery of the rings as shown in the plan Fig. 3.
It will be observed that each secondary coil consists in this case of three complete
turns of the copper strip or plate around the core C. The intervening pieces 4, 4,
which are placed between the turns of the secondary coil to separate them from
each other, are of insulating material, such as vulcanite. The core C of the
converter consists of lengths of soft iron telegraph wire laid upon each other in the
form of a circle, with breaks between their ends, and without the lengths of wire
being insulated from each other. The insulation 4, 4, is however, so arranged as to
prevent the core from touching the secondary coils. The secondary coils are
attached in parallel to the conducting rings B', B.
Between the secondary coils the primary coils 5, 5, are placed upon the core,
being wound upon wooden or vulcanite spools, through the hole in the centre of
which the core passes. These spools insulate the turns of the primary coils from
the conducting rings B1, B2, from the secondary coils and from the converter. Each
pair of these spools is connected in series and its positive and negative terminals
are also connected to the positive and negative terminal points T', T, which receive
the corresponding terminals of the electric circuit 6, which is in turn connected to
the source of the primary current. It will of course be understood that the primary
circuit wires of the converter are insulated by being wound with suitable material.
The terminals T¹, T', of the primary circuit are supported upon the wooden base, W,

page_text: in the centre of the converter. The primary coils 5, 5, in the converter consist of
comparatively fine wire and a large number of turns upon the spools while the
secondary coils consist of large copper sheets or plates bent edgeways. with com-
paratively few turns around the core.
The other single converter, which goes to make up the compound one, is formed
of a pair of conveying rings X1, X2, corresponding to B', B, just described, and
each of its secondary coils has its terminals attached in parallel to these rings, the
only difference in construction being that each secondary coil makes but two turns
around the core, C, instead of three complete turns as in the first converter. The
primary coils 5, 5, are also made of fine wire with more turns on their spools than
the primary coils of the first converter, as is clearly shown in Fig. 3. The effect
of this construction is, that the single couverter last described converts the primary
current into a secondary current of lower potential than the first converter above
described. The object of this invention is to use these two currents in a compound
converter in varying proportions, or alternately, or successively in the heating of
metals.
It is well known that in the heating of metals by the electric current, such as
iron, steel, or brass, the resistance of the bar increases quite rapidly as it becomes
heated up to about 400 degrees. It, therefore, requires a higher potential in the
heating current to force it through the bar after it becomes thus heated than when
it begins to be heated by the current. When a single converter is used the degree
of reduction of the potential of the heating current has to be arranged with relation
to this property of the bar to increase its resistance as the heating progresses. The
. reduction of the potential is, therefore, with the single converter not so low as to
provide for the most economical heating of the bar in the outset, and is somewhat
lower than is desirable for the most economical heating of the bar after it has
reached the temperature of 400 degrees.
In other words, to meet the requirements of the heating the current is a wasteful
one and in the case of some metals much more so than with others.
I propose to avoid these difficulties by employing a compound converter consisting
of two single converters, which reduce the primary currents of different potential,
and so arrange and connect these two converters that their secondary currents may
be applied to the heating, or maintaining the heat of the same bar at different stages
in the heating process. For this purpose I employ the following mechanism :
Depending from the positive and negative conducting rings B', B³, of the upper
converter are the arms ', 6, and depending from the conducting rings X', X³, of
the lower converter are the arms x¹, x². The lower ends of these arms are in line
with each other and are turned out cylindrically, so as to form the upper half of a
bearing, in which a shaft may be turned. Brackets D, D, are bolted to the under
side of the casing of the converter, being properly insulated therefrom by the
insulating strips d. These brackets carry on their lower ends the stands d¹, d², and
on these stands are mounted the clamps C1, C2, which are bolted to the stands by
the bolts and nuts c, (Fig. 2) and in these the bar C to be heated is held.
It must be understood that these clamps and stands are of copper, or other
suitable material, which will conduct the electricity with sufficient ease to prevent
heating.
From the stand d', extend upward the arms b³, r³, which have their upper ends
in line with the downwardly projecting arms a, b, and their upper ends are
rounded out to form the other part of the bearing in which the shaft, s¹, is made to
turn. The outer end of this shaft is provided with the handles s², for revolving it,
and the inner end is journaled in the box s³.
Between the cupped out ends of the arms, on the shaft, the bosses or cylinders e, e,
revolve. These bosses are almost in contact with the arms and have extending
through them the copper blocks, e, which are made of such dimensions that when
the shaft s' is turned in one direction to the proper point they can be made to rest
in the spaces between the arms 6, 6, for example without touching them. But the
copper block, e, which comes between the arms a, a, is set at a different angle on

page_text: the shaft s' from the one which comes between the arms 61, 63, so that the shaft s',
may be turned to the position which will throw the arms b', b, partly or entirely
out of connection with each other, or vice versa.
Another pair of arms 6, x, rise from the stand d³, so as to correspond with the
arms band, in the manner just described for the stand d', and a shaft s', with
bosses e, e, bearing s³, and handles, is provided to connect and disconnect the
arms &,, with the arms 62, 23, in the manner described.
In operating the compound converter the current from the lower rings X1, X2, is
first turned on to the bar C, and begins to heat it with a current of very small
potential and very heavy. When the heating process has continued until the
resistance of the bar requires a current of higher potential, to force it through the
bar economically, the shafts & are turned by means of the handles, &, and the lower
converter is thrown out of action instantaneously and the current of the upper
converter thrown onto the bar which, being of a higher electrical tension, completes
the heating in the most economical manner.
By turning the shafts s' slowly to the proper point, a portion of one current and
a portion of the other current from the two converters may be used conjointly,
which is of considerable advantage in some cases.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In an electric current converter the combination of positive and negative
rings connected to the secondary circuit of the converter and detachable con-
ductors of electricity connected to said rings.
2. In an electric current converter, the combination of positive and negative
rings connected to the secondary circuit of the converter and detachable con-
ductors of electricity connected to said rings and composed of bars of metal.
3. In an electric current converter, the combination of positive and negative
rings arranged on the exterior of the converter and connected to the secondary
circuit of the converter and detachable electric conductors composed of bars of
metal, and metal holding devices adjustable on said conductors.
4. An electric converter for converting electric currents by induction from a
higher to a lower potential provided with two continuous rings of different
polarity disposed on the outside of the converter and connected with opposite
terminals of the secondary coils thereof.
5. In an electric current converter, the combination of a converter for converting
electric currents from a higher to a lower potential provided with rings of
opposite polarity connected to opposite terminals of the secondary coils and
disposed on the exterior of the converter, and metal holders connected with said
rings for holding the metal to be heated.
6. The combination, in an apparatus for electric heating, of metal holders
arranged to hold the metal to be heated, with two converters arranged to
furnish electric currents of different potential to the metal during the heating
process, substantially as described.
7. The combination, in an apparatus for electric heating, of metal holders
arranged to hold the metal to be heated, with two converters arranged to furnish
electric currents of different potential, and intervening connecting mechanism
arranged to connect and disconnect either of said converters from the metal
holders at the will of the operator, substantially as described.
8. The method of heating metal by the electric currents, which consists in com-
mencing the heating process with a current of lower potential, and when the
resistance of the metal is increased by the heat in employing a current of higher
potential to complete the heating process, substantially as described.
9. The combination of two converters, divided arms or conductors, x³, 24,
and 3, 6, and ¹, 6³, and z¹, 2³, respectively having movable conducting blocks of
metal interposed between their parts, and metal holders arranged to hold the

page_text: metal to be heated by the electric currents flowing through them from said
converters, substantially as described.
10. The combination of two converters, divided arms or conductors x, x²,
and 62, 6, and b, 18, and x, x³ connected thereto and respectively having rotating
conducting blocks of metal interposed between their parts, and metal holders
arranged to hold the metal to be heated, and connected to said conductors, substan-
tially as described.
11. The combination of the metal holder C', the two converters, the divided
conductors b', 63, and x, x³, connecting the metal holder with the converters; and
the shaft carrying metal blocks arranged to partially or wholly disconnect the
parts of one conductor when it connects the parts of the other one, substantially as
described.
Witnesses :-
GEORGE DEXTER BURTON.
Ettie F. Philipson,
Stenographer,
Boston, Mass., U.S.A.
FRED J. HUTCHINSON,
Attorney at Law,
209, Washington Street, Boston, Mass., U.SA.
Haseltine Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.