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Патент USA US2407120

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Sept. 3, 1946.
G. P. wlLsoN
I
2,407,120
IP PROCESS ING
Fv‘iled May 22, 1944
‘
INVENTOR.
' G'OIderP W801:
BY
i 1
2150mm?
Patented Sept. 3, 1946
2,407,120
UNITED STATES PATENT OFFICE
2,407,120
STRIP PROCESSING
Golder P. Wilson, Alton, Ill., assignor to Olin In
dustries, Inc., a. corporation of Delaware
Application May 22, 1944, Serial‘ No. 536,752
6 Claims.
1
(01. 219-13)
2
This invention relates to the heating of metal
offered by such contact bars, and, in some in
stances the contact parts are subject to exces
strip by means of electric induction.
sive wear requiring frequent replacement.
It has heretofore been Well known that the
heating of metal can be accomplished by electric
All such prior methods and apparatus for the
induction by employing the transformer principle
electric induction heat-treating of metal have
in which a primary coil is supplied with an alter
been attended by one or more serious disadvan
tages and it is an object of this invention to pro
nating electric current, and the work, or metal to
be heated, when placed in inductive relationship
vide an improved method and apparatus over
coming all such objections.
with the primary coil, is heated by its resistance
to the induced electric or magnetic current.
Another object of this invention is to provide
10
Various methods and apparatus have been de
an improved method and apparatus for the effi
scribed heretofore for bringing the metal into
cient and economical continuous heating of
inductive relationship with the primary coil. For
metal strip by electric induction.
instance, in one method for treating metal strip,
Another object of the invention is to provide
a length of the strip was rolled up to provide a
an improved. process and an eiiicient electric in
ring formed of several layers of the strip and
the ring was then heated by the current induced
therein from a surrounding primary coil. Such
methods and apparatus have the disadvantages
of‘ being limited to intermittent operation, and
duction furnace for economically effecting the
continuous heat treatment of metal strip having
either high or low electrical conductivity.
in the case of very thin wide strip, the individual
layers in the ring tend to become warped at the
higher temperatures due to their own weight,
and owing to the large cross section of the ring
formed by the layers of strip, a current of very
high amperage must be induced in order to bring
, Still another object of the invention is to pro
vide an improved process and an electric induc
tion furnace suitable for the heating of a non
magnetic metal such as a copper alloy in the
form of strip.
Other objects and advantage will become ap
~ parent from the description and accompanying
drawing, in which the ?gure is a diagrammatic
the ring to the effective temperature.
perspective view of a metal strip treating appara
In another method, the strip was continuously
tus illustrating an embodiment of this invention.
passed in an axial direction through a primary
The above objects and advantages are accom
coil, the metal being heated by the locally in- ‘ plished in accordance with this invention by- pro
duced magnetic and electric eddy currents.
viding a novel process and apparatus in which
Such methods and apparatus have the disadvan
metal strip is unwound‘ from a coil of metal strip,
tage that with high conductivity non-magnetic
passed through an alternating electromagnetic
strip it is dii?cult to induce electrical eddy cur
?eld and again brought in contact with the coil,
rents of suf?cient magnitude to bring the strip to . thus forming a secondary or complete electric
an effective treating temperature.
circuit from the metal strip itself, with heating
According to other methods, the metal in the
being effected by the resistance of the metal to
form of wire, or coiled rod, was fed in the paths
the current induced in the loop.
of a helix around, or through, a primary coil, but
Referring‘ to the drawing, the metal strip l is
such methods and apparatus have among others
unwound from the coil of metal strip 2, passes
the disadvantage of not being suitable for use
over support roll 5, through the laminated iron
with wide strip, due to the di?iculty involved in
core 6 with primary coil 1 having leads 8 and 9,
forming such strip into a helix.
passes over support roll [0, around and in con
According to still another method for heating .
tact with the outer layer of metal strip I in coil
metal in the form of wire or strip, two such wires 45 2,, and is wound up into coil II on support roll or
or strips were continuously passed in parallel
reel 12 which is driven by motor l3‘. The support
paths on opposite sides of a primary coil. A com
roll or reel 3 for coil 2 may be coupled to a mo
plete electrical circuit about the primary coil
tor or drag-generator such as illustrated at 4.
through the wires or strips was provided by
In passing around the coil 2, the wide surface of
means of contact bars having rollers on their 50 the strip I is in contact with the outer layer of
ends in electrical contact with the moving wires
the coil 2 and is bent around a substantial por
or strips. Such methods and apparatus, in which
tion of the surface of the coil 2 so that a large
contact bars and the like are employed, have the
area of contact is provided with a good electrical
disadvantage that a portion of the induced cur
connection and low amperage per square inch
rent is consumed in overcoming the resistance 55 between the strip 1 and the outer layer of coil 2
2,407,120
3
to prevent arcing and burning. A complete sec
ondary electric circuit is thus provided by the
moving strip I around the primary coil ‘I.
An alternating electric current, which may be
of either high or low frequency or, for instance, 6
any of the available standard commercial fre
quencies, is applied to the primary leads 8 and
4
Due to the proximity of the secondary loop and
the primary coil 1 and the good electrical con
nection between the strip I and the coil 2, a very
high power factor may be obtained, for instance
as high as 0.90 or higher. If it is desired, for in
stance, to bright anneal brass, this may readily
be accomplished by enclosing the furnace in a
9, and the strip is heated by the current induced
housing supplied with an inert atmosphere in the
in the loop. The temperature of the strip can
usual manner, If no such housing is used, any
be regulated either by varying the speed at which 10 oxide ?lm or discoloration, which may form on
the strip travels or by varying the power sup
the strip at the annealing temperature employed,
plied to the primary coil ‘I, The core 6 may be
-may be readily removed by passing the strip
mounted on any suitable support and the rollers
through an acid pickling solution.
3, 5, I0 and I2 may likewise be mounted on any
In addition to annealing treatments, this in
suitable support. If the rollers 3, 5 and ID are 15 vention is applicable to other heat treatments, for
made of metal or other electrical conductors, care
instance, it may be used for “normalizing,”
must be taken to avoid providing any electrical
“quenching,” and “drawing” of steel strips, for
connection between them through their supports,
the re?owing of tin on iron strip, for making
since the induced current may then flow through
copper clad steel sheets or other laminated sheet,
the supports instead of being con?ned to the
and the like.
strip I. Such short circuiting can be avoided with
The heating unit can be-made relatively small
metal rolls in any of the well known ways, for
and simple and sturdy in construction. The in
instance, by supplying the rolls with bearings
vention accordingly provides for the economical,
made of an insulator or by providing separate
continuous heating of metal in strip form and has
supports or supports made of an insulator. It is
a wide ?eld of utility without being subject to all
preferred, however, to form the rolls themselves
the disadvantages obtained with prior processes
from an insulator.
and apparatus.
If desired, spray systems, such as illustrated at
It is understood that the embodiments of the
I4 and I5, may be employed to spray ?uid on the
present invention as shown and described are only
strip I for cleaning or temperature controlling
illustrated and, that the scope of the invention is
purposes. For instance, the spray system at I5
may be employed to cool the strip I prior to con
tact with the coil 2. In operation, the portion of
the strip I brought in contact with the coil 2 is
preferably maintained at the same temperature
as the outer layer of the coil 2, so that there will
not to be limited thereby except insofar as is de
?ned in the following claims.
be no tendency for the loop formed of strip I to
continuously increase in size.
Any other suitable means may be employed for
bination which comprises an alternating electro
magnetic ?eld, means for unwinding metal strip
from a coil, means for advancing said strip
Having thus described the invention, what is
claimed and desired to secureby Letters Patent
is:
1. In an electric inductionfurnace, the com
supplying the alternating electromagnetic ?eld. 40 through said alternating electromagnetic ?eld,
For instance, the primary induction means may
consist of a primary coil ‘I wound about a leg of
the core 6 outside the loop of strip, or may consist
of a coreless primary coil disposed within the loop
of strip.
' In accordance with this invention magnetic or
and means for bringing said strip and said coil
together to provide an electrical contact there
between.
2. In an electric induction furnace, the com~
45 bination which comprises a primary induction
means, means for unwinding metal strip from a
nonmagnetic metal of either high or low electri
cal conductivity may be continuously heated in
the form of ?at strip having any desired width,
coil, means for advancing said strip around and
in inductive relation to the primary induction
means, and contacting means for bringing said
Likewise, the heating may be accomplished by 50 strip and said coil together to provide an elec
applying current to the primary coil of any de
trical contact therebetween.
sired frequency within practical limits.
3. In an electric induction furnace, the com“
When the coil 2 is completely unwound, a new
bination which comprises means for unwinding
coil is inserted on the roll or reel 3 and the strip
metal strip from a coil thereof, means for hold
is again threaded through the furnace, or if de 55 ing said moving strip out of contact with said
sired, suitable stitching apparatus may be em
coil, means for bringing said strip and said coil
together again to provide an electrical contact
ployed for fastening the end of the strip from coil
2 to the end of the strip from the new coil so
therebetween, and means for inducing an electric
current in the electrical loop formed by said strip
that a strip is fed through the furnace without
interruption. Good electrical connection between 60 and said coil.
the strip I and the coil 2 is provided, since the
Ll. In an electric induction furnace the com
bination which comprises means for unwinding
strip I and the outer layer of coil 2 are constantly
metal strip from a coil thereof, means for hold~
changing their contact surface, and little or no
ing said moving strip out of contact with said
oxidation can take place to increase the electri
cal resistance at these points of contact, The 65 coil, roller means for bringing said moving strip
and said coil together again to provide an elec
strip after passing over coil 2 can, if desired, be
passed through a quenching or pickling tank be
trical contact therebetween, and means for in
ducing an electric current in the electrical loop
fore being wound up again on coil II. In an
formed ‘by said strip and said coil.
nealing metal strip, it is desirable to obtain an
nealed strip having a certain degree of hardness 70 5. In an electric induction furnace for heating
metal strip the combination which comprises a
and this can be readily accomplished by chang
support roll for holding a coil of metal strip,
ing either the speed of travel of the strip or the
power input to the primary, or both, until the
means for unwinding the strip from said coil, a
temperature and time of treatment necessary for
primary induction means, support rolls for guid
the desired strip hardness is obtained.
75 ing said moving strip around and in inductive
2,407,120
6
5
relation to said primary induction means, and
contacting means for bringing said moving strip
and said coil together to provide an electrical con
tact therebetween.
6. In an electric induction furnace for heating
metal strip the combination which comprises
means for supporting a coil of metal strip, means
for unwinding the metal strip from said coil, a
primary induction means, support rolls for guid
ing said moving metal strip around and in in
ductive relation to said primary induction means,
roller means for bringing said strip and said coil
together again after said strip has passed around
said primary induction means, means for cool
ing said strip before it is again contacted 'With
said coil, and means for supplying an alternating
electric current to said primary induction means.
-
GOLDER P. WILSON.
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