Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
` lOS;~670
The present inventio~ relates to a process for
impro~ing the qualit~ of steel sections. ~he term
"section~" should be u~derstood as includ~ng, according
to the present in~ention, I-beams, channels, a~gle irons,
Tees, plate~, laxge ~heets, flat bars, and sheet~, ~nd
generally any rolled se¢tion ha~ing at lea~t one flat
face.
~he pro¢es~ ac¢ording to the i~ention may be applied
to ~illed steels or semiskilled ~teel~ or r~ming steel~.
~e m~in qualitie~ required b~ the users in steel
se¢tion~ are, among others, a~ high as possible ultimate
ten~ile ~tre~s, limit Or ela~ticity, and impact strength
~ ~or the grade o~ steel u~ed, a~ well as satis~actory
`~ weldability, fatigue ~trength, ~nd ductility for the
intended use o~ the steel section.
~o impro~e weldabilit~ and du¢tility of a steel it
i~ necessary to decrease it6 carbo~ and manganese eontent,
which i~ turn results in a decrease in ~t~ ten~ile strength.
~-~ Io remedy th~s incon~enience, the steel ma~ be sub~eGted
to a ~u~table cooling process, preferably dire¢tly applied
- at the outlet o~ the roll~ng mill, wh~¢h permits eertain
~; eharacteri tics of the seetion to be impro~ed to some
e~tent~
8hould 8UC~ a cooling prooess result ~n an impro~ement
:~ : .
deemed insufficient a~ far as properties of the seetions
'~J ~re co~cerned, one may resort to other proeesses to
; co~plement the mere cooling action. ~mong such processe~,
~ re~erence should be made particularly to that which compri~es
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~o5~670
adding dispersoid elements (Nb, V) to refine the steel
grain and to cause hardening of ferrite by precipitation
of such elements. ~his procedure is surely effective but
has the inconvenience of a cost which increases in
proportion as one aims at a higher limit of elasticity;
it is also the more expensive the larger the dimensions of
the sections.
What is desired is a process which permits the
above-mentioned inco~veniences to be avoided without
increasing to an unacceptable extent the carbon and manganese
contents in the steel of the sections concerned which
would otherwise result in detrimental effects on their
weldability and impact strength at low temperature.
,! ~he present invention provides a process for improving
the quality of a steel sectio~ having at least one flat face,
the process comprising at the outlet of the finishing stand
of a section rolling mill, subjecting only the outer layer
of a flat face of the section to surface quenching by means
of a cooling fluid in a cooling zone, the cooling fluid
being a suspension of a liquid in a gas, and adausting the
conditions of the said cooling so that, at the outlet of
the cooling zone, the unquenched parts of the section are at
a temperature still sufficiently high to temper the quenched
face, and so that the austenite is transformed into ferrite
'~'`'!, ~ ~ 25 and carbides in the unquenced parts of the section.
Depending upon the operating conditions for carrying
` out the process, the surface layer due to the section
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quenching comprises tempered martensite or bainite.
The cooling fluid preferably comprises water (an
aqueous suspension or solution of mineral salts and/or
surfactants, for example) in the form of a mist (a
suspension of a liquid in a gas, such as air or steam).
~he cooling fluid may be projected at supersonic speed.
From the practical point of view, a section can be
cooled to the desired extent by suitably choosing the
~3 cooling apparatuses and by suitably adjusting the length
''! 10 and the relative position of such apparatuses, such as
, cooling sprayers.
~he process according to the invention permits
sections of a special type to be obtained, such sections -
having at least one flat face whose outer layer comprises
tempered bainite and/or tempered martensite and the other
parts consist of ferrite and carbides.
According to an advantageous modification of the
process of the invention, it is possible, during the
;, surface quenching operation, to control the temperature
increase of the product by maintaining the heat exchange
between the fluid and the product in substantially
optimum conditions. ~his modification is oharacterised
. ~
in that the intense surface cooling operation of the
; product is performed in at least two steps separated by
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a stage duri~g wh~ch temperature homogeniz~tio~ t~ke~
place a~ least at the ~kin o~ the product.
According to such modification, the product i3
inten~ely cooled i~ several suaces~ive stage~ o~ ~hort
duration ~eparated by periods of temperat~re homogenization
for the product skin, at least the 1A~ cooliQg ~tage
en~uring the martensitic and~or bainitic ~uenching o~
the rolled product.
~ccording to A WaY of carrying out the pxocess o~
the in~ention, one determine~ the number and the c~nditio~s
ror carrying out the ~arious cooling a~d te~per~ture
homogenizatio~ stage~ for the produet to ensure optimum
; remo~al of heat from the product. According to this wa~
o~ ¢arryi~g out the process, the optimum ¢o~di~ions for
removins heat are determined by mean, of a diagram
indicating the ~ariat-lon of the heat flow as a functio~
of the temperature at the ~urfa¢e of the processed product.
In pra¢tice, i~ a first heavy ¢ooli~g stasef, th~f
temperature at the surfa¢e of the rolled prod~ct i~ ~owered
down to a ls~el slightly lower than the temperature
corresponding to the maximum value of heat flow; cooling
is stopped for a short Interval whi¢h results in a
tempera~uxe in¢rease at the ~kin owing to the ef~e~t o~
heat being supplied from the ¢ore; a new cool~ng sta3e is
~tartèd whefn the temperature at the surfa~e attains a
le~el ~lightly higher than the t6mpe~rature corresponding
~o the maximum ~lue o~ heat flow.
~he applica~ion of the ~arious succe~,si~ei stages, or
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lOS'~670
step~ then resultiQ~ in~mai~tainin$ the skin temperature
within limits corresponding to heat exchange conditionR
close to the optimum OnO8-
Owing to the optimum condition~ ensured by the
. 5 process according to the ~e~tion, surface guenchiDg of
the rolled product i8 performed with minimum consu~ption
of water and/or by means Or a shorter i~stallation.
The proces~ ac¢ording to the invention may be easil~
3 a~d.adva~t~geou~ly employed ~or the manufa¢ture of rails
for railways. In such an appiication, at the outlet o~
. the f~n;shing sta~d of a rail rolling mill, the upper part
o~ the rail flange is sub~e¢ted to surfa¢e quen¢hing by
~, meaus of a suitable cooling fluid, and the conditions
of the said ¢ool~g are ad~ustea 80 t.hat, at the outlet of
1g the zone of cool~ng by the fluid, the unquenched part of
the flange is at.a suffi¢ie~t temperature to permit, while
~ the rail is on the ¢ooler, the ~uenched surfa¢e layer
consisting then o~ martens~te or bainite to be tempered
.~ and the austenite to be transformed into rerrite and
~1 , . .
~ ~ 20 aarbide~ in the said un~uenched part.
~`.1
1~ ~he pre~ent i~vention also relate~ to a stsel
,1. . .
section ha~ing a ¢omposite structure obtained b~ mea~s Or
.3
the above-described process.
. AB me~tioned above, it is well know thab one ob~ain~
section3 whose propertie~ ha~e been impro~ed substantially
ow~ng to grain re~ining obtained through suitable heat
'~ treatments or b~ adding e1ements ~uch as niobium, ~or
e~a~ple. A steol s~ctio~ having such fine gra~n combines
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105'~670
a ~ood ductility with a ~atis~actory limit Or elasti¢ity.
In view o~ the process according to the in~e~tion
when applied to such section~, a steel i8 obtained whose
most complex structure gives a section both m~chanical
characteristics co~siderably improved with respe¢t to
those of the above-mentioned ~ections a~d, the mecha~i¢al
characteristics being equal, a particularly economic
character, this economy beiug due ~or ex~mple to the fact
that such ¢haracteristics are obtained with lower alloy-
element co~tent~, or b~ usin~ a ~iemikilled steel rather
than a killed one.
~he steel section accordi~g to the present invention
has a stru¢ture, in a cro~-section take~ in a plane
normal to it3 a~i~, having at least two zones sub~tanti~lly
parallel to the ~urface o~ the flat element ~orming the
-~ ~e¢tio~, one of these zones comprising untempered bainite
aDd u~te~pered ferrite-pearlite.
~i Ihe section ac¢ording to the invention may ¢omprise
i an intermediate zone between the said t~o zones, the
intermediate zone substantially consi~ting of untempered
bai~ite.
According to an advantaBeous modification Or the
~ ~tru¢ture of the above-defi~ed section, the zone comprising
-1 tempered marten~ite a~d untempered bainit~ i~ also covered,
; on t~e ~ide thereof oppo~ite to the zone comprisin~
~-~ untempered bainits and ferrite-pearlite, by a zone mainly
co~8i8ting 0~ pure tempered marten~ite.
Accord~ng to ano~her ad~antageou~ modi$icatio~ o$
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105;~670
such ~tructure, the zo~e compri~ing untemp~red bainite
and ferrite-pearlite i8 ad~acent to a layer mainly
consisting of untempered ferrite-pe~rlite, on ths side
thereof opposite to the zone com~rising untempered
bainite and tempered mart~n~ite~
Of course, according to the present in~ention, when
cooling is applied to the two faces o$ a flat product
or a sectiQn eompris~ng ~lat part~, it ~hould be under-
stood that the coD~iguration of th- various zone~ for~;ng
the structure of the flat se¢tion generally follows the
configuration Or the product or the se¢tion itself.
~he invention will be described further, by way
~, of exa~ple only, with reference to the accompanying
;~i drawing6, in which:-
Figure 1 i~ a cros~-~e¢tion through part of a flat
~ecticn;
Figure 2 i8 a side ele~ation of apparatus for ~ooling
i, a beam;
Figure 3 is a cro~s-section of the apparatus of
Figure 2;
Figuro 4 is a side elevation of apparatus for
, cooling a flat product;
Figure 5 is a side ele~ation Or part or a similar
apparatus for cooling a ~lat product; and
Figure~ 6 to 8 photomicrograph~ of steel sections.
Figure 1 show~ a portion of the cross-~ection Or one
$ype of flat section which was quenched at its two faces.
~he ~ection has zones 1 and 1' mainly comprising pure
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105'~670
tempered m~rten~ite, zones 2 and 2' compri~in~ tempered
; marten3ite and untempered bain;te, ~one~ 3 and 3'
comprising untempered bainits and untempered ferrite-
pearlite, a~d a zone 4 mainl~ comprising untempered
ferrite-pearlite.
From a practical point of view, the desired aoolin~
Or the se¢tion is obtained by choosing the cooling
de~ices and by suitably adjusting the length and the
`relati~ position of these devices such a3 coolin~
spra~ers.
~he apparatus ~or processing sections ma~ comprise
a container formin3 the reservoir for the cooling fluid
a~d ha~ing fluid feeding means, a wall of the ¢ontainer
being a perforated wall which has oririce~ arra~ged to
atomiz0 the ¢ooling fluid onto ~he surra~e Or the section
whi¢h i8 con~e~ed past the said perforated wall.
When the flat se¢tion such a~ a hot-rolled sheet has
to be cooled at its two races, it is advantageous to
combi~e two apparatusos according to the invention, the
, ~ .
~ 20 atomized ~ets Or such element being opposite to each
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other, and to displace the section through the tunnel
thu~ formed.
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` ~c~ording to a constructi~e embodiment Or the
-~ - apparatus of the in~ention, ~he perforated wall has,
2~ trans~ersely to the direction of mo~ement Or the product,
q a dimeniion at least equ~l to the width of the part to
~ bo treated.
. . ..
~1 Whe~, aGco~ding to the inventio~, step b~ step
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105'~670
quenchlng i8 planned for a given section, use is m~de
o~ an installation of the type described aboYe but having
at lea3t two coolin~ apparatuses arranged in series a~d
separat0d by a re-heating zone for the product skin.
Particularly in such a case, the cooling apparatuses
; used ad~antageou~ly have a high hea~ transfer coe~ficient,
such apparatu~es preferably having means for ad~usting
the cooling fluid flow.
In a particular embodiment of the in~tallation
according to su¢h modification, at least ona of the
re-heating zones o~ the se¢tion skin has a de~ice such as
a hood to ds¢rsase the heat removal rate.
In another embodiment of the in~tallation, at least
on~ of the cooli~g zone~ ~or the se¢tion skin has
: 15 de~i¢e arranged to heat the product.
~he a¢comp~nying drawi~gs show an apparatu~ arranged
to aool a beam (~igures 2 and ~) and a flat product whil~
beine rolled (~igures 4 and 5).
~igure 2 shows a se¢tion 11 'Gre~ beam) while being
rolled in the direction of the arrow 12. A carriage 14 is
arried on the upper flange 13 of ~he beam 11 through
roller~ 15.
~ he carriage 14 is maintained in position by an
''~! abutmen~ (not shown) and the ¢arrying rollers 15 rotate
~i 25 ~hile ~he beam 11 i8 displaced. ~he carriage 14 ha~
¢ooling ~luid containers 6 supplisd with ¢ooling fluid
, ;,
~ia conduits 17. ~he position of the contain~rs 16 i8
ad~ustad with re~pect to the beam 11 b~ ~ean~ of screwq 18
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105;~670
and hand whee; 19. The co~ection between the ~crew
18 and the containers 1'6 i8 not shown, for simplicity of
the ~rawi~gs.
A similar apparatu~, i.e. a container 112, i~
-locatod u~der the lowor flan~e 110 of the section 11,
while the inner part 111 of the ~langes i8 u~der la~eral
~ets, on the two sides, by means of suitable sprayers 113
and 114 (~ee Figure 3~ which spray air and water.
According to the ~vention, apparatuses different
from th~s cooling fluid orifices outside the co~tainer~ 16
or 112 may be employed ~uch as in the form of a transverse
~lot or a pattern of small diameter oririces.
The exa~ple given below pormits the gual~ty
improvement or the sections obtai~ed by carr~ng out the
process of the i~ven~ion to be appr~sciated. he section
i exam~ned i~ a Gre~ beam DIN 40 of an aluminium ~nd ~ilicon
killed ~teel containing 0.165% C and 1.~2h Mn. This beam
leave~ thes rolling mill rough-rolled at 8 temperature o~
j 800C to 850C a~d has the follow~ng characteristics
;~ 20 without applying the proce-~s Or the i~ention:
- limit Or olasticit~ 38 ~gf/mm2
ultimate tensile ~tress 55 kgf/mm2
- impact ~trs~gth 5 ~gr m/cm2 at -20C
~he ~ame beam lea~ mg the rolling mill in the same
temperature co~ditions ha~ the followi~g characteristics 7
after applicatio~ of the proce~s of the invention (~ntense
~urface-cooling) for 10 se¢ond~.
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105'~S,70
- limit of elasticity 45 kgf/mm2
- ult~mate tensile stres~ 60 ksf/mm2 -`
- impact strength 9.0 kgf m/cm2 at -~0C.
~he~e characteristics were obtained by means o~ a
coolin~ apparatus operating in the following operating
¢ondition~:
- rolling speed 1 m/~
- cooling time 10 8
- length Or the cooling sprayer 10 m
- water enclosure~ (containers 16 and 112)
formed or elements of 100 mm in the rolling
direetio~.
Distanee with respect to the seetio~: ~ to 6 mm
!~ , Water pressure : 1 to 3 kg/cm2
Water flow : 15 to 50 m3/h
-sprayers: eonvergent - diverge~t
-diameter of the neck : one mm
~ -air pressure : 4 kg/¢m2
'''`'~! -a~r flow : 1.5 to 2.5 Nm3/h
. ~ ,,
20 -water pressure : 3 to 4 kg/em'
-water flow : 5 el/mi~
-di~tanee with respe¢t to th~ web o~ the se¢tion: 100 mm
- -distance b~tween sprayers: 100 mm
. -temperàtures: at the ~n~et: below the Ae~ point
-~1 25 at the outlet: from 600C to 700C
.~:: (betwesn 10 and 20 seeonds after
lsaving the`¢ooling sprayers).
. ~ ,
~ he photomi¢rographs of Figures 6 and 7 show ~arious
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~05'~670
~tructures of a fla~ge of a be~m DIN 40 treated in
accordance with the ~n~ention: Figure 6 shows the skin
structure of ~uch a flangs ~tempered martensite and/or
baLnite~; Figure 7 ~hows the ~tructure at 7.5 mm from
the skin of the external face of suGh glange (ferr~te ~
carbide ~tructure). Fi~ure 8 sho~s the structure of the
same flange not being treated a¢cording to the invention.
~he structure comprises ferrite~ and carbides with
coarser grains sin¢e the cooli4g speed is ~lower.
With~n the ~cope o~ the above de~cr~bdd apparatu~e~,
in order to considsrably increase the cooling powsr o~ the
u~ed fluids, it i~ advantageou~ to apply them in a lami~ar
configuration. Such apparatu~, for cxample using water,
comprises at lea~t one b~f~le portion whose configuration
causes the cooling liquid su¢cessively to cha~ge direction
several time~, the total length of the baffle and the
dime~ions Or the fluid passage being ~uch that the ~low
3 of the coolin~ liquid throughout the apparatus is
.~ .
-~ laminar.
In a con~tru¢tional embodiment of the invention,
more rpecificall~ adapted to th~ treatment o~ flat
~eGtions such as she~ts, a ~eries of ~prayers of the
abo~e-des¢ribed type with their outlet ~lits ro~ the
cooling liquid par~llel to each other is arranged
., ,~ .
- 25 substa~tially in the ~ame plane.
~^ In a particular modification of such apparatu~
,
~ according to ~he invention, the straight length preceding
:~J, the outlet lit comprise~ an element ~uch as a corrugated
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105;~67C~
element, arra~ged in the direction o~ the liquid flow to
better ensure a laminar flow o~ the ~et. Such an element
18 is indicated in Figure 2 of ths draw mgs.
Figure 4 shows a modification of the apparatus
accordi~g to the invention, particul~rly auitable for
ensuring quick and controlled cooling of flat rolled
products at the outlet of the finishing roller~. -
~ccord~ng to this embodiment, the apparatus comprise~
in succes~ion:
(a) a cooling water case, possibl~ with a double wall,
(b) ~ d~ying air case,
(c) agai~ a cooling ca~e of the type referred to under (a)
or the like, and one or more cooling water ca~e~ of
the double-wall type but arxa~ged to be lecated
be~we~n two ~uccessive roller~ at a standard distance
from o~e ~nother.
~he cooling case 21 of the tgpe referred to u~der ~a)
and illuslrated in Figure 4 is assoc~ated with a certain
number of transport rollers 22, 23, lower rollers de~igned
to carry and to ¢o~vey a strip or sheet 24 to be cooled,
the sheet being displaced in the direction o~ the arrow 25.
he cooling case 21 comprises two ~uccessive part~,
the fir~t Or whi¢h i8 an lnlet container 26 having a roof
; downwardly inclined in the d~rection Or movement of the
;~ 25 ~heet, ~wo Bide wall8 27 a~d 28 located at the ends of
the rollars 22 a~d 23, a lower wall 29 located below the
sheet 24 and leavi~g little space between itsslf and the
rollers 22 and 23, wbile being slightl~ inclined downwards
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lns;~670
~n the direction indicated b~ the arrow 25. ~he second
of the succ~si~e parts of the ca~o 21 comprise~ a
container 210 lower in height tha~ the inlet of the
container 26 a~d haa a sub3tantiall~ horizontal roof 211,
while the bottom wall 212 i9 located at a short distance
from the two ~d~ace~t rollers 23 a~d 213 and i8 ~lightlyincli~ed
in a d~ection opposite to that indicated by the arrow 25.
~he cooling case 21 has a de~ice 214 located at the
upper part of the inlet of the roo~ of the contai~er 26
-; 10 and arr~nged to e~e¢t one or more water ~ets in~ids the
~- container in the direction of the roller 80 as to ~mpinge
upon its upper zone 215. A pair of rollor~ 21~ and 217
~ i8 advantageously located before the container 26, the roller
-i 216 being a caxr~ins roller and bei~g located at the usual
;' 15 le~el under the sheet 24, the second roller 17 beingdispla¢ed ~pwards to ¢orrectly guide the sheet 24 towards
the i~let of khe ¢ontainer 26, independently of the
surface ir.regularities of the ~heet even at its end. The
excess of water is discharged from this container past
, 20 the roller 23.
: The ¢ooling case ~ust de~cribed has the following
. , .
:; advantage~:
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~, ` 1. ~he water ejected by the device 214 i~ guided
along the rolled ~heet 24 owing to the limited space
.3 25 between the roof 211 of the container and the sheet 24.
-~ 2. Pos~ibility of a¢ceptin~ without di~ficulty sheets
- ha~ing sur~ace irregularitie~.
3. Po~sibili~y o~ actin~ on the water distributio~
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lOS'~670
depe~ding ~n the width of the sheet b~ selecting one
or ~ore water jets.
4. Possibility of di~placing the 3heet by directing
; the water ~ets onto the sheet at the zone where it rests
on the roller 23. The sheet is thuæ urged into the
container 210. In practice, the water flow to ~uch
co~tainer is high (of the order of 1000 m3/h) under
relati~ely low pre~sure (about 1 kg/cm2). With these
; data, heat transfer coefficients of the order of 0.1
cal/cm2.~ C are frequently attai~ed.
~ he dr~ing air case referred to under (b) and
indicated as 218 in Figure 4 is sssociated with at least
two rollers 2~ and 219 carrying the ~heet Z4 while it
moves through the ca~e 218. ~he height Or the pas~age cross-
section of this case is ~ufficient to allow the shest togo through, ao¢ount being taken of the fact that the sheet
may haYe surface irregularities which might result in
rela~iTely large dimensions.
The roof of the case 218 has a number o~ orifica~ 220
through which a large amount of dry gas su¢h a~ air can
be blown under low pre3sure 80 as to form an air cu~on
~ between the wall and the sheet and to define a barrier
a~ for the water covering the sheet a~ the outlet of the
, ¢ontsiner 210. This operation has the ad~antage that the
subsequent cooling step can thus be carried out on a dry
~heet, which considerably increases its efficiency.
~ he cooling water case 221 of double-wall type such
dicated i~ Figure 5, has ~n priaciple the Rame general
~ - 15 _
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105'~70
configuration as the case 21, except that it~ upper part 222
and its lower part 223 following the roller 22~ are both
doubled by a wall 225 and 226 having orifices 227 through
which water i8 e~ected agaI~st the ~heet, these orifices
being fed with water ~ia conduits 228 and 229. Thi8
arrangement pormit~ a better distribution of the water
on the sheet and a pra¢tically symmetrieal cooling
thereof to be obtained.
According to the in~e~tion, in the ¢ase where not
much room is a~ailable for locating the abo~e de~cribed
apparatuses, it i~ ad~a~tageously pos3ible to use a
8u¢ce~sion of ¢ooling apparatuses of the double-wall
ease tgpe, for exa~ple arranged from abo~e do~wards
between the carrying ~ollers arranged at standard distance
from ea¢h other. Each of these apparatuses comprises a
double-wall contaiQer within which the ~heet to be cooled
is displaced. Such co~tainer~ have two openi~gs, an
upper ope~ing and a lower opening, for feeding a cooling
liguid inside the container the inner wall8 0~ whi¢h
~ 20 have orifices arranged to e~ect liquid onto the two
'.'-! face~ of the sheet-
Thi~ de~ice, particularly adapted to the troatm~nt
of a m~al sheet while being rolled and hea~ily ¢ooled,
eomprises, arra~ged one after the other, at least:
. :! 25 (a) a case (callea the inlet ca~e) comprising means for
,.q
l water-cool^ng the sheet.
-i (b) a case (called an air drying case) comprisi~g meanQ
for remoYi~g from the sheet the water applied to it
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1(~5'~670
while going throu~h the inlet case.
According to an intere~ting modification of thi~
apparatus, it further ¢omprises at least one double-wall
container arranged to water cool the ~heet at the outlet
of the dryin~ ca~e, and a member arranged to dry the sheet
at the outlet of the double-wall container.
The inlet case ad~antageou~ly co~prises a container
havin~ two distinct parts, the fir~t of which, on ~he
inlet side of the sheet, has a height decreasin~ down
to ri~ht abo~e the upper generatrix of a rcller, the
upper part Or this roller being located inside the said
f caRe, owing to the presence of a~ opening formed in thebottom wall of the said ¢a~e, th0 roof of the second part
being sub~ta~tially horizontal with respect to the plane
t~ken a~ a referen¢e plane for the shest goin~ through
the ca~e, the botto~ wall~ Or the two parts of the case,
one being arranged before said roller and the other
a~ter it, are slightly in¢lined towards said roller
1 . without touching it; moreo~er, on the inlet side of the
., 20 #heet, the ¢a~e has a devi¢e arranged to o~ect water
: onto th~ upper part of the shoet substantially in the
dire¢tion of th~ zone where the said shcet, a~sumed to
.; be pl~ne, ¢o~tacts the said roller, the roller ¢arrging
~ the ~heet and con~e~ing it towards the outlet of said
., ~ .i
: 25 case.
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, The dr~ing ~a~e ¢omprise~, according to a preferred
smbodime~t, a co~tainer which iB ope~ at its ends to permit
the pas8ag8 therethrough of the sheet to be treated,
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the roof of the said con~ainer being ~ubstantially
parallel to the plane o~ the sheet and bei~g double-
walled, the outer wall having an orifice for connectio~
to a pres~urized air supplying in~tallation, the inner
wall havin~ a ~umber of orifiae~ along most of it~
length arranged to permit air to be blown o~to the sheet,
the bottom wall of Qaid container having at l~a~t one
recess arranged to allow the upper part o* a sheet
~ carrying and conveying rollers to be introduced into
: 10 the container.
~he double-wall container for feeding water
adva~tageously comprises an elongated case in the diraction
:J ' of moveme~t of ths sheet, the case being open at its two
ends ~nd compri~ing two di~tinct parts, the first of which,
o~ the inlet side, has a height de¢rea~iDg approximatoly
to right above the upper generatrix of a roller, the
upper part of this roller being located inside 3aid ¢ase
owing to ths presence of an opening formed in the bottom
wall of ~aid case, the roof of ~he second part being
substantially horiæontal ~ith re~pect to the plane taken
;,
. as a refersnce plane for the sheet pas~ing throu~h the
oase, in that the bottom walls of two parts of the case,
one o~ w~i¢h is loca~éd before ~aid roller a~d the other
after it, are slightly i~clined towards s~d roller
without ¢o~tacting it, the roof~ of sa~d two parts as
well a~ the bottom wall of ~h~ second part ha~ing a
double-wall the outer element of which ha~.an opening
.il for the connection to a water 8uppl~ device, whereas the
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105;~670
inner elemant has a ~eries Or orifice3 arra~ed to e~ect
water onto the two face~ of the sheet.
~¢¢ording to another interestIng 6mbodiment o~
the double wall container, being designed to be arranged
verti¢ally a~ove the spAce between two ~uc¢essively
rolling rollers, the container ¢omprises a simple
parallelepipedic case, with neither an inlet nor an
outlet wall, in the direction of movement of the sheet,
the roof and the bottom wall of the case bei~g double-
walled, the outer wall~ thereof having an opening for the
¢on~ection to a water supply devi¢e, wherea~ the Inner
walls haYe a serie~ of orifice~ arra~ged to psrmit ths
e~e¢tion Or water onto the two fa¢e~ of the sheet.
~he member which i~ arra~ged to dry the sheet at
the outlet of tbe double-wall container advantageou~ly
comprises a du¢t the outlet se¢tion of whi¢h is in the
form of a narrow horizontal slit Pnd its orientation i8
such bhat the plane air ~et ~rom it impinges the wetted
~heet at a very ~mall a~gle, ~o as to permit an ea~
adju tment o~ the water flow o~ the upper fa¢e of the
~ ~heet; the water e~ected against the lower ~a¢e of the
~heet being eliminated owing to t~e pre~sure exerted
'i Rgainst th~ face by the roller on whi¢h the sheet i8
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- di~placsd.
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