Channel-type induction furnace of the teapot type

A channel-type induction furnace of the teapot type comprising a crucible having a bottom, a channel-type inductor in the bottom and having a partially semi-circular channel opening into said bottom, and straight inlet and outlet melt conduits respectively extending to and from the bottom and positioned substantially tangentially with respect to said channel so as to extend straight into and from the channel.

A channel-type induction furnace of the teapot type comprises a crucible 
having a bottom, a channel-type inductor in that bottom, and inlet and 
outlet melt conduits on opposite sides of the crucible and respectively 
extending from a level above the crucible melt level to and from the 
bottom of the crucible or close to it. An example of such a furnace is 
illustrated by the Archenholtz U.S. Pat. No. 4,415,362. 
The above furnace and others of its type can be tapped by tilting the 
furnace towards its melt outlet conduit, the melt inlet and outlet 
conduits being on the opposite sides of the crucible. Conventionally, the 
inductor is a separate unit attached to the crucible bottom. The inductor 
channel openings are consequently offset from the bottoms of the two melt 
conduits with the result that after tapping for the purposes of completely 
emptying the furnace crucible a sump of melt remains in the inductor 
channel. It takes an undesirable time for this sump to cool enough to 
permit servicing of the crucible and conduit refractory lining possibly 
requiring removal of the inductor. 
Briefly summarized, the present invention is an improved channel-type 
induction furnace of the teapot type in which the inductor has a partially 
semi-circular channel opening into the crucible bottom, and straight inlet 
and outlet melt conduits respectively extending at opposite angularities 
to and from the crucible bottom and positioned tangentially with respect 
to the inductor's channel so as to extend straight into and from the 
channel. This construction permits the inductor to be made as an integral 
part of the furnace. All parts contacted by the melt must comprise a 
refractory lining of the usual type and with this new construction the 
crucible, inductor channel and the two conduits can be and are formed by a 
mutually integral refractory lining. The refractory lining is contained 
and supported by the usual steel shell construction and the inductor coil 
and core can be passed through the inductor lining via holes formed 
through the shell and the refractory of the furnace construction. However, 
all of the refractory lining of the inductor and crucible together with 
the conduit linings are integrated or monolithic. 
With this new furnace a melt poured in the inlet conduit flows straight 
into the inductor channel and through it smoothly up into the crucible and 
the outlet conduit. With the inductor channel openings free from 
turbulent-creating deviations, the furnace operation is smoother, and 
tapping by furnace tilting creates less melt disturbance. Finally, when 
the furnace is to be shut down tilting can completely empty the entire 
furnace including the inductor channel. No sump remains in the furnace. 
Being completely empty of melt the furnace cools more quickly so that 
cleaning and repair of its entire lining can be carried out.

In FIG. 3 showing the conventional furnace the inlet and outlet melt 
conduits 1 and 2 respectively are straight. However, the removable 
inductor 3 must have its channel 4 out of alignment with the conduits. 
Such a furnace may characteristically have a gas inlet 5 opening into the 
space 6 which forms above a melt in the furnace. The inductor channel 4 is 
symmetrical with respect to the center line 7 of the furnace, but it is 
not only semi-circular but has straight vertical extensions leading to the 
bottom of the furnace crucible. There is no practical way to empty the 
channel 4 of its normal sump of melt. 
The new furnace construction shown by FIGS. 1 and 2 has straight inlet and 
outlet melt conduits 8 and 9 respectively and its overall integral or 
monolithic lining is constructed so as to form a refractory inductor core 
lining 10 and a channel 11 of partially semi-circular contour and with 
which the conduits 8 and 9 extend tangentially. The integral or monolithic 
furnace lining and its steel shell SS are constructed to form side opening 
10' through which the necessary inductor iron core 10" can extend, this 
part being completely separated from the melt by the lining 10. 
Tapping can be controlled by a stopper rod 12 for a stopper opening 12' in 
the top of the outlet 13 of the outlet conduit 9. The crucible 14 extends 
upwardly and may be provided with a pressure tight lid 15. 
The furnace lining L extends integrally throughout the conduits 8 and 9, 
the inductor lining 10 and the lining of the crucible 14. Only the core 
and its winding or coil 16, are removable and they need not ordinarily be 
removed. The melt can flow into and from the inductor channel 11 with 
little or no turbulence and that for tapping the entire channel can be 
freed of sump metal by tilting. This is due to the straight conduits 8 and 
9 and their tangential arrangement with respect to the partially 
semi-circular channel 11, permitting the conduits to extend straight to 
and from this channel without deviations of any kind.