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Патент USA US2104886

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Jan. 11, 1938.
Filed Aug. 7, 1935
(4 2
g ‘4 ,
Patented Jan. 11, 1938
Wilhelm Rohn, Hanau-on-the-Main, Germany,
assignor to the ?rm Heraens-Vacunmschmelxe
Aktiengesellschaft, Banan-on-the-Main, Ger
Application August '7, 1935, Serial No. 85,094
In (lemony April 80, 1934
This invention relates to improvements in elec
trically heated annealing furnaces, more especial
ly in vertlcaLbright annealing furnaces, for strips
with a protective atmosphere.
Furnaces of the kind referred to have been de
scribed in which the annealing zone is located
immediately above the cooling and preheating
zone and the material to be treated is passed over
a reversing roll arranged in the top portion of the
1° furnace.
The object of the present invention is to pro
vide a furnace of this kind the construction of
which involves a very low expense and the sub
stantial parts of which may be easily exchanged.
A furnace according to the invention is illus
trated by way of example in‘ the annexed draw
ing in which Fig. 1 is a vertical section; Fig. 2
is a vertical section in a plane normal to the sec
tion of Fig. 1; and Fig. 3 is a horizontal section
90 along plane 3-3 of Figs. 1 and 2.
Referring to these Pigs. 1, 2, and 3, A, B is the
casing of the furnace consisting of two concen
tric sheet metal cylinders, the space between
which is ?lled with a heat-insulating material C.
The top end of the furnace is closed by a cover D
?tting into a ring shaped oil seal E. P is a ?lling
of heat-insulating material. The reversing roll
0 is secured to the cover by means of a holder H
which also supports the heating element J. The
strip K to be annealed coming from below, is
passed between the inner wall 13 of the casing
and the heating element and over the roll 0 and
then again on the other side downwards between
the heating element J and the wall D.
By the arrangement here described I attain
above all that the essential parts of the furnace,
viz. the heating element and the reversing roll,
may easily be exchanged. These parts, more
over, are relatively small and easy to manufac
ture. As the casing is constructed as simple as
possible, it may be built up even by a smaller fac
tory desiring to erect a bright annealing plant,
and the cover carrying the reversing roll and the
heating element may-then only be put on this
45 simple casing.
A further advantage of the above-described
construction consists in that the heating element
is arranged in the interior of the annealing cham
ber and therefore is surrounded by a hydrogen or
50 other protective atmosphere during the working
of the furnace. It is understood that in a hy
drogen atmosphere an electric heating element.
especially one made of a chromium-nickel alloy,
may distribute considerably more energy per
55 square unit of its surface than in air, i. e. with
the same consumption of electric energy a small
er surface area of the heating wires or ribbons
(0!. 15-2.)
and therefore a smaller total weight of the heat
ing elements will be required and a considerable
expense may be saved.
A further advantage consists in that the heat
transmission from the heating element to the
strip to be annealed is extraordinarily favourable,
no structural part intervening between the heat
ing element and the material to be treated.
To recapitulate, the described mode of con
struction combines a very simple and cheap per
formance with a very favourable ei?ciency.
It is especially useful to make the height of the
tubular chamber beneath the heating element
long enough for an exchange of the heat between
the outgoing and the ingoing strip to allow the
strip to go out at a su?‘lciently low temperature
to prevent it from oxidation.
I claim:
1. An annealing furnace comprising a vertical
ly sustained elongated chamber open at the top
and bottom to the atmosphere and having the
vertical side walls thereof insulated against the
passage of heat therethrough, a top end closure
member detachably secured in end closing posi
tion, electrical resistance heating means centrally
disposed in the upper end of said chamber, and a
roller element horizontally sustained above said
heating means centrally within said chamber and
depending from said closure member, said roller
element being adapted to receive and impart a
reverse bend to a metal strip passing thereto
through the open bottom of said chamber.
2. The combination of claim 1, said elongated
chamber comprising two concentric metal cylin
ders with the space between the cylinder walls
?lled with heat insulating material.
3. An annealing furnace comprising a vertical
ly sustained elongated chamber normally closed
at the top and open at the bottom to the atmos
phere and having vertical side walls thereof insu
lated against the passage of heat therethrough,
electrical resistance heating means suspended
from the top and centrally disposed in the upper
end of said chamber, a roller element horizontally
sustained above said heating means centrally
within said chamber adapted to receive and im
part a reverse bend to a metal strip passing there
to through the open bottom of said chamber, the
space between the portions of the metal strip on
opposite sides of said roller being open beneath
the heating element for a sumcient distance to
permit an exchange of heat between the ingoing
and outgoing portions of the strip to allow the
strip to go out of the bottom of the chamber at a
su?iciently low temperature to prevent oxidation 66
of the strip.
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