Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to walking sill furnaces,
particularly bilateral andtor mixed heating furnaces having sills
cooled with either water or some other fluid, as used for heating
iron metallurgy products, such as slabs, billets and blooms.
With furnaces o~ this type, the products placed therein
are stepped forward while resting with their bottom sides
alternately on the stationary and walking sills. In prior
furnaces, the top surfaces of the stationary and walking sills
follow, when viewed in plan view, a parallel pattern to the
furnace longitudinal axis and to the infeed direction of -the
products through the furnace. Consequently, the products always
bear on the sills with the same contact areas of their bottom
sides. For this reason, and especially with bila~eral heating
furnaces where the sills are cooled with either water or some
other fluid and are, therefore, comparatively cold, the areas of
rest of the products onto the sills show on drawing them out of
the furnace -- owing to their contacting the sills at fixed
locations and to shielding from the burners ~- a lower tempera-
ture than the average temperature of remaining product, thusforming so-called ~black stripes". These colder black stripes
cause problems with the rolling of the heated products, such as,
for example, variations in the thickness of flat rolled stock and
seamless tubes.
In order to at~enuate the problems due to blacX
stripes, it is k~own to install on the cooled sills
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; ~ o~ ff:b~e sill furnaces of the cited type, spaced
apart riders formed from a ~pecial alloy, whereon
the products introduced into the furnace are made to
rest. Such riders act as spacers between the cooled sills
and heated products, and by virtus of the fact that the
special alloy used in their construction, can reach, at
their surfaces in contact wlth the overlying products,
much higher temperatures than those o~ the cooled
sills, while retaining ~t such higher temperatures
optimum mechanical characteristic~ in all cases
effective to prevent upsetting phenomena due to`the
weight of the products. The riders, however, have proved
to be inadequate to eliminate the black stripes, the
temperature whereof, on withdrawal from the furnace is
still appreciably lower than the average temperature
of the heated products in spite of the riders.
~ hus, to further reduce ~o~nation of the black
stripes, movable sill furnaces have been proposed
wherein the stationary and movable sills maintain
their top surfaces parallel to the flrnac~s' longitudinal
axis, and accordingly, to the direction of advance
of the products to be heated, but are split in two
transversely staggered successive sections.
Conssquently, the products change their
areas of rest onto the sills, substantially midway
through the furnace. ~ven this prior approach, while
af~ording a limited increase in the temperature of
the black stripes, has proved inadequate to obviate
the problems of the black stripes, because the products
being heated still bear for too long a tlme on the
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sllls wlth the same areas of contact, thereby local coolIng at
such rest areas reaches conslderable depth.
The Inventlon provldes for a further attenuatlon of the
problem of the aforesaid black strlpes whlch form on Iron metal-
lurgy products (slabs, blllets, blooms, and the llke) belng
heated In walklng slll furnaces, and Is partlcularly dlrected to
slgnl f Icantly decrease the depth of local coollng In Iron metal-
lurgy products at thelr areas of rest on the statlonary and walk-
Ing sllls, In partlcular cooled sllls. The Inventlon Is based onthe recognltlon that It Is hlghly Important, especlally wlth
walklng slll heatlng furnaces whlch supply rolling mllls for flat
products, such as strlps to have In the heated slabs or blllets
black strlpes whlch although shallow, are broader.
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Accordlng to the present Inventlon there Is provlded In
a walklng slll f u rnace f or heatlng metallurglcal artlcles and
havlng a longltudlnal extenslon and a longltudlnal heatlng cham-
ber wlth a longltudlnal mld-axls thereln and a plurallty of long-
Itudlnally extendlng and Juxtaposed alternatlngly arranged stat-
lonary and walklng sllls havlng duct formatlons provlded thereln
for a coolIng fluld and wlth an Inlet end at one extremlty of the
furnace and an outlet end at an opposlte extremlty thereof longl-
tudlnally spaced apart from sald one extremlty and deflnlng a
downstream dlrectlon dlrected from sald Inlet end towards sald
outlet end, arranged at each slde of sald longltudlnal mld-axls
at least one of sald longltudlnally extendlng statlonary sllls
havlng successlve statlonary sectlons thereof extendlng In a
dlrectlon havlng a convergent Incllnatlon towards sald longltu-
dlnal mld-axls ~ollowlng sald downstream dlrectlon and at least
one of sald longltudlnally extendlng walklng sllls havlng suc-
cesslve walklng sectlons thereof arranged In spaced slde-by-slde
relatlonshlp to sald statlonary sectlons and parallel thereto
wlth a convergent Incllnatlon towards sald longltudlnal mld-axls
followlng sald downstream dlrectlon, arranged at each slde of
sa Id I ong Itudlnal mld-axls at least another of sald longltudl-
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nally extendlng statlonary sllls la~erally a~ a dlstance from
sald one longltudlnally extendlng slll and havlng other succes-
slve statlonary sectlons thereof extendlng In a dlrectlon havlng
a dlvergent Incllnatlon wlth respect to sald longltudlnal mld-
axls followlng sald downstream dlrectlon and at least another ofsald longltudlnally extendlng walklng sllls havlng other suc-
cesslve walklng sectlons thereof arranged In spaced slde-by-slde
relatlonshlp to sald other successlve statlonary sectlons and
parallel thereto wlth a dlvergent Incllnatlon wlth respect to
sald longltudlnal mld-axls followlng sald downstream dlrectlon.
In a partlcular embodlment of the present Inventlon
sald successlve statlonary sectlons and sald successlve walklng
sectlons both havlng a convergent InclInatlon towards sald longl-
tudlnal mld-axls are arranged remote from sald longltudlnal mld-
axls and sald other successlve statlonary sectlons and sald other
successlve walklng sectlons both havlng a dlvergent Incllnatlon
wlth respect to sald longltudlnal mld-axls are arranged nearer to
sald longltudlnal mld-axls than sald successlve statlonary and
successlve walklng sectlons.
Thus, accordlng to the Inventlon the top surfaces of
the statlonary and walklng sllls whereon the products to be
heated rest dlrectly or Indlrectly vla rlders, follow, when
vlewed In plan vlew, over at least a part of the furnace length a
non-parallel Incllnatlon wlth respect to the longltudlnal axls of
the furnace, and speclfIcally a convergent and/or dlvergent
Incllnatlon wlth respect to the longltudlnal mld-axls of the fur-
nace, and accordlngly, wlth respect to the dlrectlon of advance
of the products through the ~urnace.
The top surface of each statlonary or walklng slll Is
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composed of several successive sections, of which at least one,
when viewed in plan view, has inclination with respect to the
~urnace longitudinal axis bu-t is con-tained withln a rela-tively
narrow band subs-tantially parallel to the furnace axis. The
individual successive sections of the top surface of each sill
are inclined in the same direction, diverging or converging with
respect to the longitudinal mid-axis of the furnace and are
staggered from one another. In another embodiment, the individ-
ual successive sections of the top surface of each sill are
inclined, specifically in an alternate fashion, in opposite
directions which may diverge from or converge toward the
longitudinal axis of the furnace, e.g. such as to form a
zigzagging line when viewed in plan view.
In at least one section of the furnace, the
corresponding inclined sections of the top surfaces of the
stationary and walking sills may be convergent to, or divergent
from, the furnace longitudinal mid-axis, or may be part-
convergent and part-divergent, in particular alternately
convergent and divergent with respect to said longitudinal mid-
axis.
The successive sections of the top surface of each sill
may be rectilinear or curved, and elther separated from or
connected to each other. In general, the top surface of each
sill, whether stationary or movable, may present -- in plan view
-- the development of either a broken, continuous, or discontinu-
ous line, comprising at least one, and preferably several
sections, inclined with respect to the longitudinal axis o the
furnace, or the development of any continuous or discontinuous
curved line, in particular one with at least one twisting or
unduIating portion.
In all cases, according to this invention, the areas of
the products being heated bearing on the top surfa~es of the
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stationary and walking sills are arranged to be constantly varied
as the products are being fed through the furnace. Accordingly,
the time period that the products being heated will rest onto the
cooled sills with the same contact areas of their boktom surfaces
is reduced, thereby the depth of the black stripes is
significantly decreased and their temperature increased. Thus,
the problems brought about by the black stripes are eliminated or
at least minimized. In addition to this main advantage, the
invention also affords a decreased length of the furnace region
reserved for making the temperature of the products being heated
uniform, and therefore, a decreased overall length of the furnace
for a given output and quality (uniform temperature) of the
heating of the iron metallurgy products, or for the same furnace
length, improved quality of the heated products.
The present invention, and the advantages afforded
thereby, will be further illustrated in a preferred embodiment
thereof, with reference to the accompanying drawings where:-
Figure 1 is a schematic horizontal cross-sectional view
of a walking sill furnace according to one embodiment of the
invention, with the sills shown in top plan view;
Figure 2 and 3 show to an enlarged scale a cross-
section taken through one half of the furnace of Figure 1,
wherein walking sills intermix with stationary sills and are
shown in a lowered (Figure 2) position and raised (Figure 3)
position;
Figure 4 is a sectional view similar to Figures 2 and 3
taken through a modified embodiment of the furnace, wherein each
of the furnace halves has two walking sills included between two
stationary sills, with the walking sills in their lowered
position; and
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Figure 5 is a vertical cross-section taken
longitudinally through the end portion of the walking sill
furnace.
Shown in the drawings is a walking slll furnace which
will be discussed hereinafter in connection with its use to heat
slabs B, blooms, and billets, for example, without excluding,
however, its use with other comparable products.
In the Figures, the numeral 1 denotes the stationary
sills and 2 the walking sills of the furnace. Over at least a
part of the furnace length, both the stationary sills 1 and
walking sills 2 have a tubular construction and are cooled by the
circulation of water or some other fluid. The walking sills 2
can be raised and lowered to alternatively move into a raised
position (Figure 3) where they pro~ec-t upwards from the support-
ing surface defined by the stationary sills 1 and from where the
slabs B are advanced, and into a lowered position (Figures 2 and
4) where they are dropped below the supporting surface defined by
the stationary sills 1 and deposit the slabs B onto the station-
ary sills 1. Further, the walking sills 2 may be shifted
horizontally, forward in the direction of the F in Figure 1 when
in their raised condition, the feed forward by one step the slabs
B, and rearward in the opposite direction to the arrow F in
Figure 1 when in their lowered condition, to make ready for the
next forward stepping of the slabs B. These movements of the
walking sills may be provided in any suitable way, e.g. in the
following known way.
The walking sills 2 are carried on tubular pillars 3,
also cooled by circulating water or any other suitable fluid
therethrough and firmly mounted on a movable lower bed 4 which is
made to rest, through carriages~5, onto fixed inclined surfaces 6
made fast with respective foundations 7. The carriages 5 are
interconnected by means of longitudinal rods ~ which are
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articulated by means of a cross-piece 9, to any actuator .such as
the piston rod 111 of an oil-operat0d cylinder 11 oscillably
~ournalled at 211. The carriages 5 rest on the inclined surfaces
6 through running wheels 105, and have supporting idler
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wheels 205, whereon the bed 4 is arranged to rest
slidably with the intermediary of longitudinal rail~
~1 104. The vertical up and down mo~ement of the
sills 2 is accomplished by moving the carriages 5
horizontally on the inclined surfaces 6 through the
oil-operated cylinder 11. ~he horizontal, lengthwise
back and forth movement of the ~ sills 2 is
provided by another oil-operated cylinder 12 which is
mounted for oscillation at 112 on a holder stand 107
secured to the ~oundation work and has its piston rod
212 linked to the movable bed 4.
The stationary sills 1 are also carried on
tubular pillars 103 which are,cooled by circulating
water or some other suitable fluid therethrough,and
affixed to the bottom 113 of the furnace. At the
movable sills 2, the bottom or hearth 113 is completed
with bottom portions 13 which are attached to the
lower bed 4 and move along therewith.
Burners 14,15 are provided both above and below
the sills 1,2, thereby providing for a bilateral
heating of the slabs B. The upper burners 14 are
located preferably on the furnace roof, whilst the
lower burners 15 may be positioned on the end walls,
as shown, and/or the side walls. The slabs B to be
heated are fed into the furnace by means of a roller
runway 17 at the inlet end. At least some of the
stationary 1 and movable 2 sills extend as far as said
roller runway 17~ and the slabs B are transferred
from the roller runwa~ 17 to the sills by means of
pushers (not shown).~Provlded at the opposite, outlet
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end of the furnace is a front withdrawal door 18 through which,
with the assistance of a specially arranged withdrawal machine
(Not shown), the heated slabs B are taken out of the furnace and
deposited onto the external roller runway 19 for transferrment to
the rolling mill. The slabs B are carried on the sills 1,2 with
the interposition of spaced apart blocks 16, also termed
"ridersll, which are fastened to the sills 1,2 and formed, for
example, from a special cobalt alloy.
Each stationary 1 or walking 2 sill is composed of a
number of successive sections 101 or 102 which, when viewed in
plan view, are inclined to the longitudinal axis A-A of the
furnace, and hence, to the direction F of advance of the slabs B.
In the embodiment shown, the successive sections 101 or 102 of
each stationary sill 1 or walking sill 2 are straight and
staggered to one another so as to fall, again in plan view,
within a comparatively narrow band extending in the longitudinal
direction of the furnace. In the embodiment of Figures 1,2 and
3, in each section of the furnace, the respective sections
101,102 of the three sills located on each side of the furnace
(i.e. two stationary sills 1 and one intervening walking sill 2~
are laid to converge toward the mid-longitudinal axis A-A of the
furnace, whilst the secticns (101,102) of the four middle sills
(i.e. two center sills 1 flanked by two walking sills 2) are set
2s divergent from the longitudinal mid-axis A-A of the furnace
relatively to the direction F of forward movement of the slabs B.
In the embodiment of Figure 4, the furnace comprises
two pairs of walking sills 2, provided on the two sides of a
middle pair of stationary sills 1 and flanked on each side of the
furnace by a stationary sill 1. In this case, ln each furnace
section, the respective sections of the sills 1,2 are alternately
convergent and divergent with respect to the longitudinal mid-
axis of the furnace.
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