Improvements in Electric Furnaces.
Year: 1895

page_text: Date of Application, 17th Apr., 1895-Accepted, 17th Apr., 1896
COMPLETE SPECIFICATION.
Improvements in Electric Furnaces.
I, GEORGE DEXTER BURTON, a citizen of the United States of America,
residing at 7 Water Street, Boston, in the County of Suffolk, in the 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 :-
This invention relates to an apparatus for heating metal to a forging, welding or
fusing beat by means of an electric or voltaic are sprung between the metal and an
electrolytic bath.
The object of the invention is to provide a simple, cheap and convenient liquid
forge especially adapted for beating any determinate lengths of bars or blanks of
metal for use in machine building or for forging into manufactured articles.
The invention consists in the combination of an electrolytic bath, a divided
non-conductive hearth therein for supporting as electrodes the work to be heated,
one member of the hearth being movable towards and from the other to vary the
distance between them, and means for establishing an electric are between the
solution and that portion of the electrode which spans the space between the parts
of the hearth.
The invention consists further in the combination with the elements above
specified of a gage for indicating the distance between the parts of the hearth so
that the hearth may be adjusted accurately at different times to heat work for
corresponding lengths.
The invention consists further in the combination with the electrolytic bath and
means for establishing an are between the bath and work of a rest or hearth
therefor composed of asbestos.
The invention consists further in the combination with the electrolytic bath and
electric conductors, and hearth of improved means for elevating and depressing the
surface of the bath in relation to the surface of the hearth.
Figure 1 of the accompanying drawings represents a plan view of this
apparatus.
Figure 2 represents a longitudinal vertical section thereof on line 2--2 of
Figure 1.
Figure 3 represents a side elevation thereof showing the improved means for
elevating and depressing the level of the liquid.
Figure 4 represents a detail of said means.
Figure 5 represents a transveise section of the apparatus on line 5-5 of
Figure 2.
Figure 6 represents a perspective view of a piece of work on which an enlarge-
ment or boss is formed at one end by heating the end in this bath and afterwards
upsetting or forging it.
Figure 7 represents a piece of angle iron bent from a straight bar after being
heated at the point where the angle is formed by resting the bar on the two
members of the divided hearth and permitting the portion to be heated to come in
contact with the bath between said members.
Figure 8 represents two electrodes of metal which have been heated by resting
them on the divided hearth and letting their ends project over the liquid, whereby
the ends are heated preparatory to the formation of a lap joint.
Figure 9 represents the two electrodes of Figure 8 welded together by a lap
joint.
Figure 10 represents a rod which has been rested on the two members of the

page_text: Dearth an utated
right angles.
between said members at its mid-length only, and then ent
Figure 11 represents a hook formed from a straight bar after the latter was
heated in this bath.
Figure 12 represents two bars or electrodes which have been heated by this
apparatus and joined together.
Figure 13 represents a double crank shaft which is formed from a straight bar,
the latter having been heated at the points of bending only by resting it upon the
two members of the hearth and letting the parts to be heated extend between said
members over the liquid, which is brought into contact with said parts..
Figure 14 represents a single crank shaft formed from a straight bar which was
heated between the members of the hearth while resting thereon.
Figure 15 represents a plan of a divided hearth composed of three members,
supporting the links of a chain which are heated for welding by being supported in
contact with the liquid between said members.
Figure 16 represents a longitudinal section of this apparatus provided with a
divided hearth the edges of which have notches adapted to receive blanks for rings
or tires for heating the ends preparatory to joining them.
Figure 17 represents a plan view of a divided hearth having uotches for this
purpose.
Figure 18 represents an anvil on which the ends of a tire blank are forged
together by a lap weld after said ends are heated in the bath.
The same reference numerals indicate the same parts in all the figures.
A vessel 10, preferably in the form of a tank, and constructed of or lined with
a material which is a non-conductor of electricity, is designed to contain an
electrolytic bath 20 through which an electric current is passed. If constructed of
wood or earthenware, this vessel is coated on its inner surface with asphaltum or
coal tar, in the same manner in which tanks for electro-plating purposes are usually
coated. Such a coating prevents the tank from absorbing the solution and thereby
avoids short-circuiting of the current through the walls of the tank, which might
occur under a heavy voltage, if such walls were saturated with the solution. This
vessel when constructed as herein shown is provided with a longitudinal partition 12
near one side, said partition having openings 13 near its bottom or otherwise, and
with a partition 14 having holes 14'. These partitions form a hearth com-
partment 15, an anode compartment 16, and a plunger compartment 17, and the
holes therein permit the solution to pass freely from one compartment of the tank
to the others.
The bath 20 partially fills the vessel 10 and is composed of an electrolyte having
a greater density than water and capable of evolving hydrogen, being an electrolyte
which will cause with the electric current under proper conditions the formation of
a voltaic arc between the metal to be heated and the solution. This bath may
consist of a solution of chloride of sodium of a density of 1.050 for small work, but
when larger pieces of metal are to be heated, the density is increased according to
the size of the article to be heated. I have used for this purpose a solution of
sodium carbonate or sal soda of a specific gravity of 1.305 at 84 degrees
Fahrenheit; also a solution of equal parts of cream of tartar or potassium
bitartrate of a specific gravity of 1.255 at 77 degrees Fahrenheit; also a solution
of water, carbonate of soda and borax in the proportions of three quarts of water to
twelve pounds of carbonate of soda and one pound of borax.
An anode plate 30 is disposed in the solution preferably in the anode
compartment 16 of the vessel 10. This anode is preferably composed of a lead
plate serrated at its upper edge forming lugs 31 which are bent in opposite
directions and engage a copper rod 32 which extends over one end of the vessel
and is provided with a binding post 33 for connection with the positive conductor
of an electric source. The location of the anode within the compartment 16
prevents contact of the work with the anode and avoids short-circuiting of the
current thereby.

page_text: A divided hearth composed of fire clay or other non-conductive material, is
supported in the vessel 10. One member 40 of this hearth is preferably adjusted
in fixed position in a recess formed in the bottom of the tank. It is preferably
provided with a smooth or flat surface at its top. The other member 50 of the
divided hearth is supported in the bath on a movable slide 51, which moves
between guide-ways 52 and 53 on the bottom of the tank. The member 50 may
thus be adjusted towards or from the member 40 to increase or decrease the
distance between said members and afford a greater or less span for electric contact
of the bath with the work supported on the divided hearth, the arc being thus
formed for a given length equal to the distance between said members. Suitable
means are provided for adjusting the slides, such as a screw rod 54 engaging a
screw threaded eye 55 in the end of the tank, said screw rod being provided with
an insulated handle 56 at its outer end.
A graduated scale 57 is disposed in proximity to the slide for the movable
member of the hearth, preferably on the top of the partition 12 of the tank. The
movable slide is provided with a pointer 58 which projects into reading contact
with said graduated scale, whereby the distance between the two members of the
divided hearth is indicated.
A plunger 60 is disposed in the plunger compartment 16 and suitable means are
provided for raising and lowering this plunger to raise and lower the level of the
liquid in the hearth compartment 15 so as to bring it into and out of contact with
the metal supported on the divided hearth. This means as shown in Figures 1.
and 2 consists of a lever 61 pivoted on a standard 62 attached to the rear of the
tank and connected at its front end to a standard 63 on the plunger, a link 64
connected at its upper end to the rear end of said lever, and a pedal 65 which
extends under the tank and is connected at its rear end with the lower end of
said link.
The preferable means for actuating the plunger as illustrated in Figures 3 and 4
consist of a lever 71 pivoted at its rear end to a standard 72 attached to the rear
end of the tank and extending forward over the top of said tank longitudinally
thereof. The plunger 70 has a slotted standard 73 which is surrounded by a
spring 74. The lever 71 rests in the slot of the standard 73 and on the spiral
spring 74 and has a yielding connection with the plunger so that when the lever is
moved suddenly the plunger will move gradually so as not to splash the liquid.
When the lever is depressed, the plunger pushes down the liquid in the plunger
compartment and causes it to flow out through the openings in the partition 12
into the hearth compartment, whereby the level of the liquid in the hearth
compartiment is elevated to a level with or above the level of the divided hearth.
A terminal 80 in the form of a bar composed of copper or other suitable
material, is supported at the front side of the tank on insulated studs 81. -One
end of this bar is provided with a socket for receiving a conductor connected with
the negative pole of the electric source and with a set screw 82 for clamping the
conductor in the socket. This bar is preferably bevelled and serves as a rest on
which the tool or implement for grasping the article to be heated may form
contact for closing the circuit, or a bar or electrode to be heated in the bath off
the hearth may be rested on this electrode and thereby be placed in circuit.
A positive conductor 90 is connected at one end with the anode plate 30 and at
the other end with the positive pole of the electric source. A conductor 91 is
connected at one end to the terminal 80 and at the other end to the negative service
wire, or negative pole of the dynamo or source of electric current.
An electrode 100 may be hinged or otherwise connected to the negative
terminal 80 and form contact with an article on the hearth. This electrode may
be forked and adapted to form contact separately with two articles on the hearth;
and it may be provided also with an intermediate arm 101 and form contact with
another article or articles on the hearth.
In the use of this apparatus for heating a bar for a definite length, the two
members 40 and 50 of the divided hearth are so adjusted relatively to each other

page_text: :
as to be a distance apart equal to the length of the portion of the bar it is desired
to heat and the bar is adjusted with its ends resting on said members and its inter-
mediate portion to be heated spanning the space between them. Then the negative
electrode 100 is brought into contact with said bar or contact is made by any
suitable means between the bar and the electrode 80. Then the plunger is
depressed and the level of the liquid in the hearth chamber is elevated into contact
with the bar and the circuit is closed. The current passes from the anode of com-
paratively large superficial contact with the liquid into the liquid without
incandescence at this point, and then through the liquid to the bar which constitutes
the cathode or negative pole. Hydrogen is evolved from the electrolyte or liquid
by the electric current and an envelope or film of such gas immediately forms
between the work and the liquid, the latter being apparently pushed away from the
work, and an electric arc is formed between the liquid and that portion of the bar
which spans the space between the two members of the hearth, whereby said
portion is heated in a few seconds to the desired working heat. The incandescent
hydrogen reinforces the direct action of the heating electric current.
In the use of the apparatus for heating two electrodes or bars of metal to be
welded together by lap joints, the two bars as. 200 and 201 are placed on the
two members of the divided hearth with their adjacent ends projecting over the
hearth and electric contact is effected by lowering the electrode 100 so that
its outer end will touch both pieces, or in any other suitable manner, and then the
level of the liquid is raised as aforesaid and those portions of the electrodes which
are to be worked project beyond the inner edges of the members of the hearth and
arcs are formed between them and the solution and they are heated quickly to the
desired temperature. They may then be removed and welded or forged in any
desired manner.
At the same time separate pieces of metal may be heated on the individual
members of the hearth as indicated in Figure 1, where a horse shoe 300 is being
heated on the movable member 50, electric contact being formed by the tool which
rests in part on the electrode 80 and in part on the horse shoe. The heel ends of
the horse shoe are shown as projected over the hearth and as the liquid rises it
comes in contact with these ends an arc is formed between them and the solution.
That portion of the shoe which rests flat on the hearth is not surrounded by an arc
and is not heated. When the heel ends are sufficiently heated the shoe is removed
and said ends are turned up to form the calks.
In the use of the apparatus for the formation of a crank shaft, the members of
the bearth are separated for a distance somewhat greater than the span of the
crank to be formed and a rod is placed on said members spanning the space
between them. That portion of the bar between the two members of the hearth is
heated as above described and then bent in the desired form.
The members of the hearth may be of a height nearly on a level with the edge
of the tank in which case the normal level of the liquid is at a point just below the
top of the hearth members.
In the use of the apparatus for welding the ends of tires or rings, as shown in
Figures 15 to 17, a blank ring or tire 400 is supported in notches 41 on the edges
of the two members of the hearth in such a manner that the ends thereof are
immersed in the liquid, which may be elevated or not, and these ends are then
heated to a welding heat and uuited on an anvil or in any suitable manner.
The hearth may be formed of molded asbestos if desired which is preferable in
the heating of files for tempering as it does not injure the teeth or cutting edges of
the file.
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 :-
1. In an electrolytic heating apparatus, the combination of a vessel for
containing an electrolytic solution. a hearth composed of two members for

page_text: supporting a metal to be heated, one of said members being movable relatively
to the other.
2. In an electrolytic heating apparatus, the combination of a vessel for
containing an electrolytic solution, a divided hearth composed of two members-
for supporting a metal to be heated, one of said members being movable relatively
to the other, a gage for indicating the adjustment of the movable member, means
for establishing an electric arc between the solution and the metal supported on
the hearth, and electric conductors for connecting the solution and metal with.
opposite electric poles.
3. In an electrolytic heating apparatus, the combination of a vessel for
containing an electrolytic solution, a divided hearth for supporting the metal to be
heated, a slide for supporting one member of said hearth, means for adjusting said
slide, and means for establishing an electric arc between the solution and the
material supported on the hearth.
4. In an electrolytic heating apparatus, the combination of a vessel for
containing an electrolytic solution, a divided hearth for supporting the metal to
be heated, a forked electrode adapted for contact with work on both members of
said hearth, and meaus for establishing an electric arc between the solution and the-
metal on the hearth.
5. In an electrolytic heating apparatus, the combination of a vessel for
containing an electrolytic solution, a divided hearth for supporting the metal to
be heated, an electrode provided with a plurality of arms of different lengths for-
contact with work on both members of said hearth, and means for establishing an.
electric arc between the solution and the metal on the hearth.
6. In an electrolytic heating apparatus, the combination of a vessel for
containing an electrolytic solution, a hearth supported in said solution, a pump.
for elevating and depressing the level of the liquid in the hearth compartiment, a
lever having a yielding connection with said pump, and means for establishing an
electric are between the solution and the metal on the hearth.
7. In an electrolytic heating apparatus, the combination of a vessel for
containing an electrolytic solution, a hearth disposed in said solution for supporting
the metal to be heated, a plunger chamber communicating with the hearth
chamber, a plunger provided with a slotted standard, a pivoted lever for operating
said plunger and engaging said slotted standard, a spring on said standard to effect
a yielding contact between the lever and the plunger, and means for establishing
an electric arc between the solution and the metal on the hearth.
8. In an electrolytic heating apparatus, the combination of a vessel for-
containing an electrolytic solution, a hearth composed of asbestos for supporting-
metal to be heated, and electric conductors for connecting the solution and metal.
with opposite electric poles.
Dated this 90th day of March 1805
Witnesses :-
FRANCES J. BURTON.
GEO. W. BLISS.
GEORGE DEXTER BURTON.