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Патент USA US2135934

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N0V~ 8, l938~
2,135,934
G. F. BLASIER
ROTARY FURNACE
2 Sheets-Sheet
Filed Dec. 17, 1937
l
l
INVENTOR
Geo/"ge Ä'ßázifer
d.
ATTORNEY
v Nov. 8, 1938.
G. F. BLASIER
2,135,934
ROTARY FURNACE
Filedv Dec. 17, 19:57
2 .Sheets-Sheet
2
l /l
lNvENToR
Üeafye Ã'ßlaszef
ATTORNEY
2,135,934
Patented Nov. 8, 1938
UNITED sTATEs PATENT OFFICE
2,135,934
ROTARY FUBNACE
George F. Blasier, North Tonawanda, N. Y., as
signer to Builalo Bolt Company, North Tona
wanda, N. Y., a corporation of New York ,
Application December 17, 1937, Serial No. 180,300
28 Claims. (Cl. 283-33)
This invention relates more particularly to
furnaces of the rotary tubular type, wherein ro
tation of the furnace is utilized for introducing.
advancing and discharging articles or materials
5 while progressively heating them by flame dis
charging into the furnace through the exit end
thereof.
`
'I'he present illustrative form was primarily
designed and is herein shown as embodied in a
10 furnace for annealing and heat treatment of
metal articles such as steel nuts, bolts, or the like,
but it will be obvious that various novel features
of construction and operation of my furnace will
be found useful in other rotary tube furnaces,
u and for heat treatment of other articles or ma
terials, for other purposes.
As shown herein, the outer tubular shell, and
the rotating, intake, exit, and name-projecting
arrangements, may be in a general way, similar to
For these reasons, it has been common to make
the inner lining and its ribs of cast iron. But
cast iron is brittle and the castings are heavy,
so the prior practice has been to build up the
inner lining from cylindrical castings each hav- 5
lng a section of the helical rib integral therewith.
These cylindrical sections may be 15 .inches to
18 inches wide. lengthwise of the furnace, so that
it may take 8 or 10 of them to complete an in
ner lining. They are supported by an interme- 10
diate lining consisting of arch brick resting on
the exterior cylinder and presenting inner cir
cular surfaces which support the cylindrical cast
ings. In practice, the arch brick interlining with
the successive cast iron sections thereon, is built l5
up progressively from one end of the furnace to
the other.
‘There are many objections to such construc
tions. One obvious objection is that the weight
of the separate inner castings, the continuous 20
rotation of the furnace, and the repeated expan
sion and contraction of the cast iron due to light
ing up and turning oil the heat, cause the cast
in place of the inner lining; novel means for sup
porting said inner shell in said outer tubular shell ings to pound themselves loose in the brick, and
independently of the intermediate insulation; a in time this necessitates re-bricking and re-lining 25
the entire furnace; and, in many 'cases the inner
novel construction for the means whereby rota
tion of said shell propels the articles or materials cast iron sections are so badly distorted by the
from the intake to the exit end of the furnace ; heat that they cannot be re-used.
In this connection, it is to be noted that both
and also novel combinations of the various novel
features with each other, and with said outer the arch brick and the cast iron cylinder sections 30
3 shell, and with its rotating, intake, exit, and afford substantially no resistance to longitudinal
tension, and they can contribute to transverse
name-projecting arrangements.
In furnaces of the above type, the cylinder may stiñness of the rotating furnace as compression
members only; and their effectiveness even for
be, say, 15 feet long, by three feet or more in
ternal diameter, and the interior is provided with this purpose depends on careful fit against one 35
another and against the exterior shell. But the
a helical flange or rib. When the cylinder is ro
tated, the articles are carried by the cylindrical ` cast iron inner lining and the arch brick have
and helical inner surfaces, up to where gravity substantially different coeilicients of expansion;
causes them to successively and progressively fall also the amount of the expansion and contrac
¿o downward so that the helical rib surfaces operate tion of the inner cast iron, is different from that 40
to propel the articles toward the exit end of the of the outer iron shell, because of the great dif
furnace.
,
ference in temperature between the interior which
For annealing and heat treatment of metal is directly heated and the exterior which is rela
articles, the inner lining and the helical flange tively cool because it is protected by intervening ‘5
is subjected to rather high temperatures, and to insulation, and is cooled by the outer air.
correspondingly high variations of temperature.
The present invention obviates these objec
For instance, in a given case, the temperature ad
tionable features by introducing an entirely new
jacent the exit end of the cylinder may be some
thing like 1500° F., while the temperature at the principle of construction.
In place of the many relatively short cast iron 5°
.50 entrance end may be only 300° or 400° F. It
sections, I substitute a single integral tubular
results that both radial and longitudinal expan
sion and shrinkage of the inner lining varies shell running the entire length of the furnace.
greatly between the exit and the entrance; and Preferably, this is made from rolled, heat-resist~
ing steel sheet or plate material, of thickness and
in the aggregate, the total amount of longitudi
55 nal expansion and shrinkage is very substantial. construction such that said inner tube shell may 55
those shown in the U. S. patent to Rockwell, No.
20
1,333,343; but the present invention relates more
particularly to a novel inner shell construction
2
2,185,934
have nearly or quite as great strength as the
outer shell.
'
'I'his inner tube shell is anchored to the ex
terior shell at one place only, preferably at the
exit opening where the finished articles fall out
of the furnace. 'I‘his would not be possible with
the old type construction described above. because
any radial expansion of the sectional cast rings
would cause them to lodge or bind tightly against
10 the insulating brick, thereby preventing free ex
pansion longitudinally of the furnace.
My inner tube shell is mounted in the outer
shell by bearing ~surfaces which permit it to be
inserted and removed endwise, as a unit, and
15 which permit it, when heated, to expand longi
tudinally by sliding in both directions from the
above described anchorage point.
preferably includes a variable speed electric
motor.
'
The supports permitting such endwise sliding,
are rings fastened to the outer shell, and they
20 have bearing members extending inward a dis
tance equal to the thickness desired for the heat
insulation; and the insulation itself is suitable
refractory aggregate which can be inserted in or
removed from the interspace without disturbing
25 either the outer shell or the inner shell.
Another feature is making the inner propelling
members in the form of short lengths of helically
disposed bar material, each length being secured
to the inside of the inner shell, by riveting, or
30 by welding, or preferably by both; and prefer
ably at certain spaced-apart points, so that the
expansion and contraction of these members may
be somewhat different from that of the inner
shell, without thereby distorting either them
35 selves, or said shell.
The above and other features of my invention
may be more fully understood from the following
description in connection with the accompanying
drawings, in which
Fig. 1 is a longitudinal sectional view in a
vertical plane including the axis of the furnace
and corresponding to the line I-l, Fig. 3;
Fig. la is a similar section of a characteristic
short length of the cylinder, but on a large scale
so as to facilitate illustrations of some details;
Fig. 2 is a diagram showing the inner cylindri
cal surface of the furnace, the entire circumfer
ence of the cylinder being unrolled to the vertical
plane of an up-turning straight line element, so
as to give a diagrammatic indication of the dis
position and operation of the successively up
turning helical flights, with respect to gravity;
.
'
(b) The articles are charged into the furnace
through opening 3, and, as the furnace rotates,
they slide to the larger diameterend of chamber
3a and are then picked up by the edge 3b of a
slanting, more or less spiral scoop 3c, which ex
tends to the peripheral wall of said chamber la.
As the furnace rotates farther, gravity causes
the articles to slide inward on the scoop, and
ultimately to fall into the furnace through the
opening 3d.
(c) A stationary hood 4 at the exit end of the
furnace, surrounds the annular path of travel of
the open outlet through which the heated articles 15
fall out of the furnace. This hood is designed
to limit escape of flame and hot gases from said
outlet, particularly during the upper half of its
rotation, when it is upwardly directed, and would
otherwise tend to act as a chimney discharging 20
directly into the open air. The upper annulus 4
connects with a stationary chute 4a, into which
the hot nuts or other articles fall when the out
let is downwardly directed as in Fig. 1. This
chute 4a serves as a connection between furnace 25
and quench tank which may contain water or
oil or other fluid for chilling or otherwise modi
fying the quality of the heated articles; or, in
case of annealing, it may contain only air, for
air-cooling.
-
(d) The burner 5, whereby flame is projected
axially into the furnace, may be of any known
30
or desired construction, as also the cooperating
insulation through which the flame is discharged,
although some features of the latter are new,
particularly as concerns the novel wayin which
the insulation is supported by the furnace.
For my purposes, the outer shell l, is prefer
ably made of rolled plate of thickness and
strength sufilcient to carry the load of the entire
rotating structure, say, It, inch thick; and the
cylinder may be built up from the plate material
in any of the ordinary ways, as by riveting and
welding, but 'for my purposes the inwardly pre
sented ends of the rivets are preferably ñush 45
with the interior surface of the shell.
The inner shell may be made from rolled steel
sheets or plates, of considerable thickness and
of heat-resisting qualities adequate for sustain
ing the structural strains and the maximum tem
peratures above indicated. For such reasons, 50
the inner shell is preferably thicker than the
Fig. 3 is an end view of the furnace, from the ' outer shell, say, % inch instead of 1l; inch.
left, Fig. 1;
55
Fig. 4 is a transverse section on the line 4-4,
Fig. 1, the granular insulating material being
omitted;
Fig. 5 is a detailed perspective showing the
laterally corrugated rings whereby the inner shell
of the furnace is supported slidably but keyed
against the rotation;
Fig. 6 is a detailed view of the inner~ shell and
one of the key strips shown in Fig. 4, but on a
much larger scale;
Fig. '7 is a detailed view showing a portion of
the inner cylinder and key strip, in perspective
An important feature of this inner shell is
making it externally smooth and uniform enough 55
so that it will be endwise slidable when it length
ens by heating or shortens by cooling; preferably
also for easy endwise insertion into and removal
from the outer shell. For these and other rea
sons, a novel construction .in accordance with 60
my present invention is highly desirable. In
my construction, the inner shell is made from
a plurality of rolled metal plates extending the
full length of the furnace. These long plates
or strips are transversely curved on the arc of
a circle of the diameter desired for the inner
as well as in section.
shell. « As shown in Fig. 4 and also on a larger
Referring first to conventional features of one
form. of furnace to which my new principles of
scale in Figs. 6 and '7, there are preferably only
two such strips 6a, 6a, each transversely curved
70 construction have been applied:
(a) The outer shell I is conventionally indi
cated as provided with riding rings 2, 2, and
to form a semi-cylinder. These semi-cylinders 70
are assembled in a practically integral cylinder
without any joints or projections except at the
rolls 2a, 2a, whereby it is supported for rotation
in the desired direction and at desired rates, by
any suitable mechanism, not shown, but which
meeting edges of the semi-cylinders. A very
effective way of making this joint, is to place
the edges of the sheets in registering contact, 75
9,135,934
before inserting them in the outer shell. Then
a long plate or strip lb. which may be, say, 3
inches wide, is secured over the contacting edges
of the sections by rivets tc. Then the two cor
ners where the edges of the strip contact the
outer surface of the shell, are welded through
` out the length of the shell, as indicated at 6d.
A long rectangular bar le, is next placed edge
wise along the center of this strip, and welded
to it throughoutdts entire length as indicated
at if. These bars ld, 6e are utilized as a spline
whereby the inner shell is endwise slidable, but
is keyed against rotation.
»
As shown in Fig. l, this inner shell is slidably
16 supported in the outer shell. by end bearings,
and by suitably spaced intermediate bearings 1, 1;
which latter are preferably castings of metal ca
pable of withstanding high temperature, prefer
ably a nickel-chrome alloy such as Misco. As
20 shown in Fig. 5, each bearing 1 is an annulus
of lrelatively thin metal reversely curved in trans
verse accordion-like fiutings 1a, of which the
outer and inner edges, 1d, 1e, constitute cylin
drically disposed bearing surfaces. The depth
of the flutings determines the effective width of
the bearing `surface lengthwise of the furnace.
In a- particular case, the ilutings were '1 inches
high radially; 3 inches lengthwise of the fur
nace; and the metal was % inch thick.
30
Edgewise, the' thin metal is substantially ra
dial, so that the annulus affords rigid support
-for the inner shell; but the transverse flutings
areA springy, so that heat >expansion or distortion
of the annulus takes effect only as slight cir
35 cumferential compression of said fiutings, with
out anydistorting or binding effect on the shells.
To permit »such functioning, the annulus is an
chored to the bute'r sneu only-at intervals', with
one, or preferably several, intervening iiutings
unanchored; and, for similar reasons, the an
chorages are preferably on adjacent convex bends
on the same face lof the casting, as indicated in
Fig. l and Fig. 5, where angle fittings, 1b, are
shown as welded to the flutings and bolted to
the outer shell.
'
l
As shown in Figs. 5 and 6, opposite flutings
are cut away to form keyways 'Ic for the flat
strips Gb and the key bars 5e. As shown, there
is substantial clearance space between the keys
and keyways, as also between the inner shell l
v
3
is rigidly secured between ends of outer shell i,
and supply chamber la..
The six slidable bearings described above have
incidental advantages in connection with the
construction and assembly of the parts of the
furnace. When the end closures la, ib, are re
moved, or before they are put in place, the inner
shell 8 formed as above described, and provided
with an outlet casting, Sz, welded thereto, easily
slides endwise through the ring bearings, until 10
its free end slides over the outer surface of said
inwardly projecting annulus ie.
The anchorage of the inner shell to the outer
shell is then effected by means of a somewhat
larger outlet casting im, which surrounds the
outlet casting 6x and is bolted to the outer shell
i. The thin clearance space between these cast
ings is' then filled solid with refractory pack
ing. Thus, the inner shell is securely anchored
to the outer shell as concerns longitudinal move
ment; and as above described, the inner shell is
free to expand longitudinally, in both directions
from this anchorage, toward the firing end, and
also toward the intake end. Thereafter the semi
circular closure sections la, Ib, are bolted toone
another and to the outer shell, thereby closing
the interspace between shells and affording a
wide bearing surface on which this end of the
inner shell may slide.
The projecting end of the inner shell 8, car
ries the internally coned insulation 5a for spread
ing the flame, and this is preferably built in after
said shell 8 has been put in place. Thereafter
the'smaller name directing insulating members
5b, 5c, are arranged in the end closure Ih of
inner shell 6, and said closure is then secured
to the end of said inner shell 6. The fuel pro
lector l can be then placed in position.
After the inner shell 6 is in position, "the in
terspaces between the ring bearings 1, are filled
with refractory insulating material. As indi
cated at 8, I, Figs. 1 and 2, this is preferably
loose aggregate or lump material, preferably free
from fine particles. This material may be broken
fire brick, but I prefera burnt slate product
known as “Haytite". A satisfactory range of the
sizes for the lumps, includes such as will pass a
one-inch screen and such as will not pass a
half-inch screen. Such sizes are too large to pass
through the clearance spaces between the inner
and the bearingrings 1. "Experience shows that
with the construction described above, an all
shell and the bearing surfaces; but in time tum
around clearance of about ñ of an inch when
will tend to sift out through all bearing surfaces;
and my construction is designed to obviate ob
jectionable effects which would result.
the parts are coldj/is sufficient. In practice, this
does not involve any undue looseness. it being
only sufficient to allow a' good endwise sliding nt
when the furnace is hot.
There are also,- slidable bearings between inner
and outer shells at each end of the furnace.
As shown in Fig. 1, the exit end of the inner
shell 6 extends beyond the end of the outer shell
i, and, as shown in Fig. 3, this end of the outer
shell is closed in by an annulus which is made
in two semi-circular sections, la and l_b,`secured
together by bolts, and, as indicated in Fig. 1,
rigidly bolted to an angular annulus which is
welded to the outer shell i. The end closure
has a broad cylindrical extension ic which,
through an intermediate thin packing id, affords
70 a slidable bearing for this end of the inr‘er shell.
At the other end, the inner surface of the
inner shell 6 has slidable engagement with the
outside surface of a projecting annulus le. which
is preferably'cast on an end closure ld, which
bling of the loose aggregate during rotation, will
wear off or break off some nner pieces, and these
Sifting out at the exit end of the furnace is
made difllcult, by having the broad close fitting
bearing surface at Ic, ld, but, as a further pre
caution, I provide a clamping ring 5g; and,
after the furnace has been heated up and nor
mal maximum expansion of the inner shell l
has been effected, this ring is set tight against
the end of bearing Ic, and is rigidly~clamped
in place. When the furnace cools, causing end
wise shrinkage toward the interior of the fur
nace, it also causes radial shrinkage, thereby re
lieving the tightness of the ring.
At the other end, where the inner shell has
maximum longitudinal movement when con 70
tracted and expanded by heat, some difficulty is
encountered, but this is taken care of by pack
ing this interspace with steel turnings 8a. which
catch and hold any particles of aggregate that
might otherwise escape in this direction. Pref»
4
2,185,984
erably the steel turnings are prevented from
reaching the place where the free end of inner
shell 6 slides on annulus le, by an annular parti
tion If, which is rigidly secured to the outer shell
I, but is not secured to inner shell 8.
Sitting from one compartment to another,
through the ring bearings 1, is not objectionable
because the bearing surfaces afforded by the in
ner edges of the corrugations are too narrow to
10 permit any accumulation’of the abraded insulat
ing material, such as would prevent free endwise
sliding of the shell.
Manholes of suitable size and location for pack
ing the aggregate and steel turnings into the
15 lnterspaces between the inner and outer shells
are assumed; and are more or less diagrammati
cally indicated on Fig. 1 as having cover plates
Ig, which are thick enough and are secured by
bolts and nuts strong enough so that structural
strength of the outer shell l, is not impaired by
the manholes.
While a furnace such as above described might
be mounted on an inclined axis -so that progress
of the articles or materials from entrance to
25 exit would be partly or even wholly, by rotary
tumbling, the primary purpose of the whole de
sign, is to successfully apply interior ribs or seg
ments adapted to uniformly feed, tumble and
heat a continuous stream of the articles or ma
30 terials, when the axis is horizontal, or approxi
mately so.
’
In the prior art, the ribs used for propelling
the articles through the furnace, particularly
those near the hot exit end of the furnace, are
35 so high that their innermost edges are close to
the axial flame whereby the furnace is heated,
and said ribs necessarily get much hotter than
the cylinder part of the casting. Consequently,
repeated heating and cooling brought about great
distortion of the entire casting, so much so that
the casting would break loose from the brick,
and'wreck the interior. Even before this hap
pened, the helical rib segments would become
misaligned, thereby affording lodging places
where some of the articles would be held and
mined by overheating. These primary condi
tions are what brought about my idea of making
the inner lining continuous.
At first, ll assumed that for my continuous
inner lining I would have to have fairly high
ribs, as in the prior art, and I tried a continu
ous helix made up in sections and secured to
the inner lining by riveting and welding. These
sections consisted of helical castings, L-shaped
in cross-section, but with rib height only about
two inches.
However, I found in practice that even with
this greatly reduced cross-section, unequal con
traction and expansion by repeated heating and
cooling, operated to greatly distort the continu
ous inner shell.
My next thought was to make the helix from
rectangular sections of very much less height, ap
proximately 1 inch high and 11/2 inches wide.
This would ailord only 1 inch of forward wedg
ing surface for- propelling a stream of articles
that may be two inches or more in depth. In
such case the tendency would _be for the helix to
act positively on only the lower layers of the
70 stream. The feed would be thus much less posi
tive and would allow much more slip than the
high ribs of the prior art. Such a continuous
helix can be built up from such sections and
with a plurality of such helices, analogous to a
2-thread or 3-thread screw, the forwardly wedg
ing surface area may be multiplied so as to give
a practically useful rate of feed, but I have dis
covered that even when built from these rectangu
lar sections only 1 inch high by 11/2 inches wide,
a continuous helix of conventional pitch, is likely
to cause distortion of the inner shell.
Ultimately I discovered that it is not necessary
to have the helix sections continuous; that I can
provide propelling surface adapted to ensure a
constant uniform flow of the material through the
furnace, by widely- interrupting and uniformly
distributing the sections, in flight formation; and
that many advantages result. 'I'he total forward
wedging area may be multiplied as much as may
be desired; the`forward wedglng angle of the
flights may be selected, independently of any
helical relation betwen them; the flights being-low
as compared with the depth of the stream of
articles, the mixing of the articles ln the stream
will be thorough and will be uniform throughoutl
the length of the furnace; and the heating will be
correspondingly uniform.
structurally considered, the pitch of the flights
may be about the same as that common for the
single helix of the prior art, so that they contrib
ute longitudinal, as well as circumferential reen
forcement for the inner lining. Apparently also
diagonal stresses due to contraction and expan
sion of the distributed diagonal flights have much
' less tendency to cause distortion of said inner lin
30
ing, than would a single helix of the same total
length. This is particularly true when the flights
are secured in accordance with my present in
vention, by riveting and welding at selected points,
widely spaced apart longitudinally of the flight.
There is of course latitude for considerable vari
ations in the forward wedging angle of the flights,
the number of flights, and their distribution, but
the arrangement shown herein has proved highly
successful in practice as concerns uniformly feed
ing a relatively deep stream of the articles
40
through the furnace; and uniformly mixing the
stream so that all articles are heated uniformly.
This applies as to a wide variety of products to be
heated, my furnace having been successfully used
where the stream consists of small articles, such
as nuts for quarter inch bolts, as well as large
articles, such as bolts 61/2 inches long by 1 1/8 inches
in diameter; the flights being an inch high and
the thickest part of the stream about 2 inches
deep. As shown in Fig. la, the flights were se
cured by Widely spaced rivets 9x, supplemented by
welding the flight to the inner shell, adjacent the
rivets only, as diagrammatically indicated at Sy.
There are, of course, many geometrical patterns
whereby the desired length of flight, affording the
desired total forward wedging area, may be at
tained. On superficial consideration, Fig. l might
seem to indicate three helical threads, each inter
rupted by Wide spaces between the ends of suc 60
cessive flights. Such an arrangement would be
practical, but as a matter of fact, uniform distri
bution of the flights, as well as flexibility as con
cerns designing the length and feed pitch of the
fli/ghts, was actually attained by following a some 65
what different geometrical theory. This is best
seen by reference to the diagram Fig. 2, which
shows the geometrical relation of the flights, with
respect to the direction of gravity and rotation,
the internal surface of the shell being unrolled 70
to a flat, vertical plane, and the flights being
identified by the same numbers as used in Fig. l.
This diagram covers the exit end and a char
acteristic adjacent length of the inner shell. This
is partly for the purpose of showing the cooper u
5
2,185,984
ative relation of the nights at the exit end, with
respect to the outlet opening 0x.
Y
The arrangement of the nights follows a `hypo
thetical helical thread indicated by the dotted line
b-c, and other lines parallel therewith. This
hypothetical thread would have a feed pitch oi
about 9°; but instead of having continuous rib
sections along this helical line, the sections have
been pitched 16° rearward of the hypohetical helix
10 line b-c. Thus the actual feed pitch of each
night with respect to the gravity line a-b, is
about 25°. This approaches, but is slightly less
than the feed angles used for the continuous helix
ahown in the above specined Rockwell patent.
Preferably, the upper end of each night aligns
15
horizontally with the lower end of the night next
above it, as for instance, any night 9 with respect
to the next night la; llt-9b; etc.
The night length is such that there are 35/2
nights, I, 9a, lb and half of 9c, for each 360° turn
of the hypothetical helix. l (See also Fig. 4.)
The
point about this is that having an odd half night
per 360° turn, brings the middle of every night in
horizontal alignment with the ends of adjacent
nights in frontof, and behind it.
In the direction of gravity, the discharge end
of each night aligns vertically with the center of
the next night below it. When the nights'are on
the upturning side. as shown in Fig. 2, this puts
successive nights in a sort of cascade relation with
respect to the down tumbling nuts. Thus, a nut
tumbling over the edge of the lower half of one
night, is likely to be intercepted by the forward
feed surface of the next lower night. `Further
more, when the nights are on the down turning
aide, near the bottom (see Fig. 1) , the leading ends
of successive nights, cut into the stream of nuts at
a point back of where they would be if each night
had been high enough to positively screw propel
all nuts in its path, instead of allowing those in
the top layer to tumble over its top edge.
Considering the nights further with respect to
the hypothetical helix lines b-c, along which
they are arranged, it will be seen that, because of
the odd half night per turn, all relations of the
nights can be shown only by considering 'l nights
that make two turns of said helix; and that is
why the nights are separately identified on the
drawings as 9, 9a, 9b. 9c, 9d, 9e, 9j; and it is only
after 9j that the arrangement repeats, beginning
again with another night 9.
shell I. Another would be spacing apart the ends
ofìall sections far enough so that nuts or bolts
could not lodge between them.
'
Even where widely separated, uniformly' dis
tributed nights are used in accordance with all
the basic principles of my present invention, it
will be obvious that either the pitch of the hypo
thetical helix or'the feed pitch of the nights, or
both, may be varied. Preferably, increase of feed
pitch of the nights would be accompanied by in 10
crease in pitch of the hypothetical helix and vice
versa.V Moreover, it is not necessary that either
the hypothetical helix, or the feed pitch of the
nights, be the same throughout the entire length
of the inner shell; and though desirable, it is 15
not essential to have the length or spacings of
the nights the same. Variations may be desira
ble for the purpose of expediting distribution and
streaming out, of the articles dumped in at the
supply end of the furnace, or to slow down the 20
feed through the middle zone of the furnace, or
to accelerate discharge through the hot end.
yCertain details of the individual nights have
speclnc advantages, regardless of how they are
distributed. Having it rectangular in cross-sec 25
tion ensures a front propelling face perpendicular
to the inner surface of the shell, so that there is
less tendency for the stream of articles to slip
over the top surface of the night. Having the
cross-section uniform as well as rectangular 30
throughout the length of the night, decreases
-tendency to unequal expansion and distortion
when heated. Having it of less height than the
deepest part of the stream of articles propelled
thereby tends to keep the temperature lower and 85
more uniform. Having it of greater width than
height gives more uniform temperature between
the hot top surface of the night and the portion
of the inner lining in contact with the bottom
surface thereof. Every fraction of an inch de
crease in height of a night gives more than pro
404
portional decrease in the straightening and dis
torting enects which normally result from any
given difference in temperature between a top
surface of a night and a radially remote bottom 45
surface. Having short nights, limits the amount
of distortion that can be applied at any one place
on the inner shell, by end to end lengthening,
straightening or distortion of the night.
Any and all of the above advantages may be
cheaply and easily attained by forming the
nights from rolled rectangular bars, cut to proper
Inspection of Fig. 1 will show that in this vlength and bent to yshape suitable for riveting
special case, there are six of these complete series and welding to the inner shell at a plurality of
of nights beginning with a night 9, and as each suitably spaced points, as above described. These
series has seven nights, there are approximately bars may be of any sufficiently heat resisting
42 nights. In this case, the night-equipped
length of the inner shell, was about 13 feet, and metal, but I prefer a nickel-chrome alloy such as
Misco.
its inner surface was about 7 feet 2 inches in cir
I claim:
.
cumference; and for these dimensions, each night
1. A tubular furnace, means for peripherally
was made approximately 261/2 inches long; so the
total night length ngures out about 93 feet for supporting and rotating it to advance a stream of
articles or materials therethrough, and means
this 13 feet length of inner shell.
for projecting a name jet in the opposite direc
If the same 25° nights were arranged as a con
tinuous 25° helix, the total night length would be tion; said furnace including an outer shell;
only 45 feet, or less. Thus two such continuous spaced-apart, inwardly-extending annular bear
helices, arranged like a two-thread screw, would ings carried by said outer shell; a cylindrical,
afford less night length than is afforded by the single-piece inner shell constructed of heat
present interrupted night relation. Obviously, resisting plate or heavy sheet metal, fitting and
any such two- hread screw arrangement, could longitudinally splined to said bearings; and re
fractory heat-insulating aggregate packed in the
be improved by two features of my present inven
tion. One would be arranging them so that joints interspaoes between said shells and said bearings;
between sections in one helix are in horizontal said inner shell extending beyond the outer shell
alignment with the center of adjacent sections at the exit end of the furnace and having there
in the other thread, thereby contributing toward in'an annulus of refractory heat insulating mate
more uniform structural stiffness of the inner rial formed with internal diverging surfaces serv
55
60
70
75
6
2,135,934
ing as an expansion nozzle for a flame jet pro
sliding except by endwise lengthening.
2. A tubular furnace, means for peripherally
supporting and rotating it to advance a stream
8. A substantially horizontal tubular furnace,
means for peripherally supporting and rotating
of articles or materials therethrough, and means
for projecting a llame jet in the opposite direc
it to advance a stream of articles or materials
therethrough, and means for projecting a flame
tion; said furnace including an outer shell;
spaced-apart, inwardly-extending annular bear
ings carried by said outer` shell; a cylindrical,
single-piece inner shell constructed of heat-re
sisting plate or heavy sheet metal, fitting and
longitudinally splined to said bearings; and re
fractory heat-insulating aggregate packed in the
interspaces between said shells and said bearings.
3. A tubular furnace, means for peripherally
supporting and rotating it to advance a stream
of articles or materials therethrough; and means
for projecting a flame jet in the opposite _direc
tion; said furnace including an outer shell;
spaced-apart,_ inwardly-extending annular bear
ings carried by said outer shell; and a cylindri
cal, single-piece inner shell constructed of heat
resisting plate or heavy sheet metal, fitting and
longitudinally splined to said bearings.
4. A tubular furnace, means for peripherally
supporting and rotating it to advance a stream
of articles or materials therethrough, and means
for projecting a flame jet in the opposite direc
tion; said furnace including an outer shell;
spaced-apart, inwardly-extending annular bear
ings carried by said outer shell; and a cylindrical,
single-piece inner shell constructed of heat-re
sisting plate or heavy sheet metal, fitting and
longitudinally splined to said bearings; said inner
35 shell extending beyond the outer shell at the exit
end of the furnace and having therein an annulus
of refractory heat insulating material formed
with internal diverging surfaces serving as an
40
of its length to said outer shell, to limit endwise
jected therethrough.
jet in the opposite direction; said furnace includ
ing an outer tubular shell capable of supporting
the entire load of the furnace and having in
wardly extending annular bearings having key
heat-resisting steel; with external rigidly-se
cured longitudinal ribs adapted to engage said
keyways, and internal rigidly-secured, inwardly-A
projecting, diagonally-disposed, forwardly feed
ing ribs of heat-resisting metal.
9. A substantially horizontal tubular furnace,
means for peripherally supporting and> rotating
it to advance a stream of articles or materials 20
therethrough, and means for projecting a flame
jet in the opposite direction; said furnace includ
ing an outer tubular shell capable of supporting
the entire load of the furnace and supporting.- co
axially therewith, a single-piece inner shell hav
ing walls of rolled plate or heavy sheet, heat
resisting steel, having external rigidly-secured
longitudinal ribs whereby the inner shell is keyed
for rotation with the outer shell, and internal
rigidly-secured, inwardly-projecting, diagonally
disposed, forwardly-feeding ribs of heat-resist
ing metal, said latter ribs being short sections of
rolled bar, bent to nt the interior surface of said
shell and secured thereto by riveting and weld
ing.
10. A substantially horizontal tubular furnace,
means for peripherally supporting and rotating
it to advance a stream of articles or materials
expansion nozzle for a flame jet projected there
therethrough, and means for projecting a flame
through.
jet in the opposite direction; said furnace includ
ing an outer tubular shell capable of supporting
the entire load of the furnace and supporting,
,
5. A tubular furnace, means for peripherally
supporting and rotating it to advance a stream of
articles or materials therethrough, and means
for projecting a flame jet in the opposite direc
45 tion; said furnace including an outer shell; a
single-piece inner shell longitudinally slidable
in said outer shell to permit lengthening when
heated, and anchored to it only in a short zone
intermediate its ends, so that said inner shell
50 is free to slide in both directions from said
anchorage when longitudinally expanded or con
tracted by heating or cooling of the furnace.
6. A tubular furnace, means for peripherally
supporting and rotating it to advance a stream
55 of articles or materials therethrough, and means
for projecting a flame jet in the opposite direc
tion; said furnace including an outer tubular
shell of rolled steel capable of supporting the
entire load of the furnace; spaced-apart, inward
ly-extending annular bearings carried by said
outer shell; a single-piece inner shell of rolled
plate or heavy sheet, heat-resisting steel, longi
tudinally slidable to permit it to lengthen when
heated; and means for anchoring only a short
65 portion of its length to said outer shell.
‘7. A tubular furnace, means for peripherally
supporting and rotating it to advance a stream of
articles or materials therethrough, and means for
projecting a flame jet in the opposite direction;
said furnace including an outer tubular shell of
rolled steel capable of supporting the entire load
of the furnace; a single-piece inner shell of rolled
plate or heavy sheet, heat-resisting steel, longi
tudinally slidable to permit it to lengthen when
75 heated; and means for anchoring a short portion
l0
ways formed therein, and a single-piece inner
shell having walls of rolled plate or heavy sheet,
coaxially therewith, a single-piece inner shell
having walls of rolled plate or heavy sheet, heat
resisting steel, having external rigidly secured
longitudinal ribs whereby the inner shell is keyed
for rotation with the outer shell, and internal
rigidly-secured, inwardly-projecting, diagonally
disposed, forwardly-feeding, ribs of heat-re
sisting metal, said latter ribs being short sections
of rolled bar, bent to fit the interior surface of
said shell and secured thereto by riveting and
Welding relatively small-area, spaced-apart por
tions of each rib section.
11. A substantially horizontal tubular furnace,
means for peripherally supporting and rotating
it to advance a stream of articles or materials
therethrough, and means for projecting a flame
jet in the opposite direction; said furnace includ
ing an outer tubular shell capable of supporting 60
the entire load of the furnace and supporting,
coaxially therewith, a single-piece inner shell
having walls of rolled plate or heavy sheet, heat
resisting steel, and having inwardly-project
ing, helically-disposed, forwardly-feeding, spaced
apart flights of heat-resisting metal, said flights
being relatively short sections of rolled bar, bent
65
to fit the interior surface of said shell and se
cured thereto by riveting and welding relatively
small area spaced apart portions of each ñight.
12. A substantially horizontal tubular furnace,
means for peripherally supporting and rotating
70
it to advance a stream of articles or materials
therethrough, and means for projecting a llame
jet in the opposite direction; said furnace includ 75
2,185,984
helical line the pitch of which is less than half
the feed pitch of the individual flights.
23. A tubular furnace, means for peripherally
ing an outer tubular shell capable of support
ing the entire load of the furnace and supporting,
coaxially therewith, a single-piece inner shell
'having walls of rolled plate or heavy sheet, heat A supporting and rotating it to advance a stream
articles or materials therethrough, and means
resisting steel, and havinginwardly-projecting, of
for
projecting a flame jet in the opposite direc
helically disposed, forwardly-feeding flights of
heat-resisting metal, riveted to the inner surface tion; said furnace including an outer shell;
spaced-apart, inwardly-extending bearings car
thereof.
<
ried by said outer shell; a single-piece inner shell
13. A substantially horizontal tubular furnace,
fitting said bearings; and refractory heat insulat l0
ing aggregrate packed in the interspaces between
said shells and said bearings; said bearings in
cluding a cylindrical bearing fitting the exterior
10 means for peripherally supporting and rotating
it to advance a stream of articles or materials
therethrough, and means for projecting a flame
jet in the opposite direction; said furnace includ
ing an outer tubular shell capable of supporting
the entire load of the furnace and supporting,
of the inner shell, carried by an annular closure
for the space between the inner and outer shells
coaxially therewith, a single-piece inner shell . at the exit end of the furnace; an external bear
ing fitting the interior of said inner shell, carried
having walls of rolled plate or heavy sheet, heat
resisting steel, and having inwardly-projecting, `by an end closure for said interspace at the en
helically disposed, forwardly-feeding flights of trance end of the furnace; and intermediate
spaced-apart ïbearings, each consisting of an
20 heat-resisting metal, rigidly secured to the inner annulus'formed as a thin metal wall substan
surface thereof, said fiights being of short length
as compared with a semi-circumference of said tially perpendicular to the axis of the furnace,
inner surface.
. 14. A furnace as specified in
and transversely curved in accordion-like fiut
.
claim 13 and in
25 which the flights are of substantially uniform,
ings affording substantial circumferential elas
15. A furnace as specified in claim `_13 and in
which the flights are of substantially uniform
rectangular cross-section and are of greater width
30 than thickness.
16. A furnace as specified in claim 13 and in
which the flights are distributed with substan
tial uniformity and are arranged in generally
mitting circumferential elastic compression of
the annulus when expanded by heat.
-
ticity; and means securing the flutings to the
outer shell only at spaced-apart intervals per
substantially rectangular cross-section.
helical relation but spaced-apart endwise.
24. A tubular furnace, means for peripherally
supporting and rotating it to advance a stream
of articles or materials therethrough, and means
for projecting a flame jet in the opposite direc
tion; said furnace including an outer shell;
spaced-apart, inwardly-extending bearings car
ried by said outer shell; and a single-piece inner
shell fitting said bearings; said bearings includ
‘
17. A substantially horizontal tubular furnace,
means for peripherally supporting and rotating it
ing a cylindrical bearing fitting the exterior of
to advance a stream of articles or materials there
through, and means for projecting a ñame jet in
the inner shell, carried by an annular closure for
the space between the inner and outer shells at
the exit end of the furnace; and an external
the opposite direction; said furnace including
40 an outer tubular shell of steel capable of support
bearing fitting the interior of said inner shell,
carried by an end closure for said interspace at
the entrance end of the furnace.
ing the entire load of the furnace; an inner cyl
inder formed from heat-resisting metal; and
means for supporting said cylinder coaxially in
said outer shell; said inner cylinder having in
45 tegrally united with the inner surface thereof,
25. A tubular furnace, means for peripherally
supporting and rotating it to advance a stream
of articles or materials therethrough, and means
inwardly-projecting, helically-disposed, forward
ly-feeding flights made of heat-resisting metal,
said flights being of short length as compared
with a semi-circumference of said inner surface,
50 and spaced-apart endwise, distances which are
great as compared with the sizes of the articles
to be propelled thereby.
18. A furnace as specified in claim 17 and in
which the flights are distributed substantially
uniformly and in overlapping relation circumfer
entially, with respect to gravity.
for projecting a ñame jet in the opposite direc
tion; said furnace including an outer shell;
spaced-apart, inwardly-extending bearings car
ried by said outer shell; and a single-piece inner
shell fitting said bearings; said bearings includ
ing spaced-apart bearings intermediate the ends
of the shells, each consisting of an annulus
formed as a thin metal wall substantially perpen
dicular to the axis of the furnace, and trans
19. A furnace as specified in claim 17 and in
versely curved in accordion-like fiutings afford
ing substantial circumferential elasticity; and
which the flights are distributed substantially
uniformly and in overlapping relation in the di
only at spaced-apart intervals permitting circum
ferential elastic compression of the annulus when
60 rection of lengthwise feed in the furnace.
~
20. A furnace as specified in claim 17, and in
which the fiights are of small height as com
pared with the depth of the stream of articles
or materials advanced thereby.
85
21. A furnace as specified in claim 17 and in
which the flights are of less height than the depth
of the stream of articles or materials advanced
thereby, and are distributed along a helical line
70 which is of low pitch as compared with the feed
pitch of the individual ñights.
22. A furnace as specified in claim 17, and in
which the flights are of less height than the depth
of the stream of articles or materials advanced
75 thereby, and are uniformly distributed along a
means securing the fiutings to the outer shell
expanded by heat.
26. A furnace as specified in claim 25, and in
which each annulus is a casting of heat-resisting
metal.
27. A furnace as specified in claim 25, and in
which each annulus is a casting of nickel-chrome
alloy.
28. A tubular furnace, means for peripherally
supporting and rotating it to advance a stream
of articles or materials therethrough, and means 70
for projecting a flame jet in the opposite direc
tion; said furnace including an outer tubular
shell of rolled steel capable of supporting the
entire load of the furnace; spaced-apart, inward
ly-extending annular bearings carried by said Il
8
2,135,034
outer shell; a. single-piece inner shell of rolled
plate or heavy sheet, heat-resisting steel, longi
tudinally slidable to permit it to lengthen when
heated: said inner shell having a radial exit chute
rigidly secured adjacent the exit end thereof, and
said outer shell having rigidly secured thereto, a
tubular member ntted to the exterior of said
chute, whereby the inner shell is anchored to the
outer shell near the exit end thereof, to prevent
endwise sliding of said inner shell except by
lengthening when heated.
GEORGE F. BLASIIERv
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