Improvements in and connected with Electric Furnaces.
Year: 1893

page_text: of Application, 28th July, 1893-Accepted, 23rd Sept., 1893
COMPLETE SPECIFICATION.
Improvements in and connected with Electric Furnaces.
I, AUGUST FRIEDRICH WILHELM KREINSEN of 64 Grosse Brunnenstrasse,
Ottensen, Schleswig-Holstein in the German Empire, Electrical 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 object of this invention, which relates to electric furnaces, is to enable metals
to be melted with great certainty and so as to obtain a cleaner product with the
castings or ingots free from flaws and blow-holes.
I will describe my invention with reference to the accompanying drawings in
which-
Figure 1 represents a vertical sectional elevation through a furnace constructed.
according to my improvements.
Figure 2 shews diagrammatically a group of crucibles arranged in series, and
Figure 3 a similar group in parallel, the former diagram representing an elevation
and the latter a plan.
Figure 4 is a vertical and Figure 5 a horizontal section of a modified form of the
furnace illustrated by Figure 1.
When metals have been melted electrically in graphite or carbon crucibles, it
has been a frequent experience that portions of the crucibles become detached, and
mixing with the molten metal; produce dirty and unsound castings and ingots. In
order to prevent this result, I arrange within the primary conducting crucible k a
secondary or lining crucible y constructed of chamotte or other non-conducting
material of a suitable character. Chamotte being a mixture of fire-clay and burnt
pottery old crucibles and the like, it will be evident that such crucibles and others
which may be used in substitution for them, will expand under the action of
heat at a different rate to the primary crucibles k, hence, if no precautions
were taken to avoid it, the secondary crucibles would be broken, whereupon the
metal would come into contact with the primary crucibles and short-circuit the
current.
In order to obviate this difficulty, I interpose between the primary and secondary
crucibles and q, an insulating shell t, of asbestos mica or analogous material
which will yield sufficiently to allow for the difference in expansion of the two
crucibles.
It has been demonstrated that in such furnaces contracting the mouth and outlet
of the crucible F, produces an economy of current by preventing radiation of heat.
But if these contractions be preserved, it will not be possible to simply pass the
secondary crucible into the primary through.its mouth, and yet, in case of damage,
and for other purposes, it may be necessary to change one or the other of the
crucibles. To enable this to be done, I divide the primary crucible / vertically
into two equal parts which are held together by the clips a b, which are included in
the electric circuit and serve to conduct the current to and from the crucible. For
the purpose of securing a perfect and constant contact between the clips ab and the
ends of the primary crucible, there is provided a strong spring, such as e, which will
tend to pull the clips in the direction of each other or will tend to pull one towards
the other.
A suitable non-conducting material d is arranged around the primary crucible,
and may be held or contained by the metallic casing m to prevent radiation.
In the case of small crucibles, I dispense with the secondary crucibles as herein-
before destribed, and substitute for it a lining of asbestos or mica or similar material

page_text: capable of resisting the heat to which it will be exposed and as shewn by Figures 4
and 5.
It is difficult to produce small crucibles from chamotte, and when they are
produced, they do not possess any durability because of their small sizes, and
it is for this reason that I substitute a lining for the secondary crucibles in such
cases.
To protect the mica or asbestos lining of the small primary crucibles, I may
provide the ends with, mouth pieces pp for the purpose of preventing injury to the
lining during the process of charging the crucibles. In such a case also, I protect
the primary crucible with a heat insulating casing & in addition to the packing d and
outer casing m for the prevention of radiation.
To enable the apparatus to be used for melting large quantities of metal, a
number of the crucibles may be arranged above the trough R common to them all.
Sec Figures 2 and 3. This arrangement provides for the adequate mixture of the
products from the several crucibles and ensures a uniform result. The trough is
constructed in its different parts in the same manner as hereinbefore described for
the crucibles, allowing for the difference in shape, and the carbon element of the
crucible is included in and heated by the clectric arc circuit. The bottom of the
trough is inclined to facilitate the running out of the collected metal.
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 electric furnace, the combination and arrangement of a primary and a
secondary crucible, of which the primary crucible is divided vertically into two parts,
substantially as and for the purpose hereinbefore described and as illustrated by the
accompanying drawings.
2. In an electric furnace, the combination and arrangement with two or
more crucibles of a collecting trough heated by an electric current, constructed
substantially as hereinbefore described and as illustrated by the accompanying
drawings.
3. In an electric furnace, the combination and arrangement with a conducting
crucible included in the electric circuit, of a heat resisting lining, and protective
mouthpieces pp constructed substantially as and for the purpose hereinbefore
described and as illustrated by the accompanying drawings.
4. The combination and arrangement with the crucible of an electric furnace
of two clips ab and a spring e constructed substantially as and for the purpose
herein before described and as illustrated by the accompanying drawings.
Dated this 26th day of July A.D. 1893.
WILLIAM E. HEYS,'
Agent for the Applicant.