Note: Descriptions are shown in the official language in which they were submitted.
~Z69Z3
The present invention relates to an important
improvement in the manufacture of blocks of polyurethane foam,
specifically the elimination, during manufacture, of the
densified bottom of the blocks obtained by the usual process.
More particularly, the invention is concerned with
an improved apparatus for manufacturing contimlous blocks of
polyurethane foam without densified areas at their bottom, in
accordance with Applicant's process which is described in his
Spanish Patent no. 466,102 issued October 1, 1978.
As is known, polyurethane foam is a plastic which
has acquired increasing importance over recent years, having
many uses in such different fields as the automotive industry
and the food industry.
In the usual process, polyurethane foam is obtained
by reacting, on a moving belt, a polyol and polyisocyanate as
principal ingredients, together with catalysts, dyes, blowing
agents, etc. The physical properties (stiffness, density,
cell size, tensile strength, etc.) of the different kinds of
polyurethane foam are a function o~ rnultiple parame~ers, the
principal ones bein~ the nature of the polyol and of the poly-
isocyanate, the ratio between both and the blowing agent.
The components in liquid state are vigorously shaken
immediately before being deposited on a mechanically operated
endless band conveyor. Between this endless band and the poured
liquids there is placed a paper web, which will follow the
conveyor in its path, so that said liquids do not spill before
they solidiy following the reaction.
The conveyor is given translatory motion, with suit-
able speed for each quality of foam. The liquids deposited
on the paper web commence reacting, being introduced, by the
movement of the band, into a tunnel having an approximate length
of 20 meters, with completion therein of the exothermic chemical
l~Z6gZ3
reaction, via which the foam is produced, increasing by several
times (approximately 50) the initial volume of the liquids.
Finally there is obtained a pliable and spongy solid which is
the polyurethane foam. Naturally, the shape of the cross-
section of said block will be that of the tunnel at its base and
side walls.
The reasons for manufacturing said polyurethane foam
inside a tunnel are as follows:
(1) To prevent dispersion of the toxic gases, prici-
pally the C02 produced in the reaction or, eventually, the to-
xic gases evaporated as a result of the heat produced.
(2) To obtain the approximate shape of the cross-
section of the bloek, achieving a body with an almost rectan-
gular section. This is usually referred to in this art as
"molding effect".
Independently of the type of foam produced, a prob-
lem associated with the manufacture of the block is the densi-
fication occuring in the bottom thereof, as a result of which
it is necessary to waste an improtant part of the f~nished
material beeause itg density i3 notably greater than that of
the rest of the block.
In addition, the bottom part of the block must be
mechanically treated to remove a eertain roughness which
remains there after removal of the web. Such roughness is
produced as a consequence of the fact that when the web on
which the block rests is withdrawn, part of the foam of the
lower zone of the block remains irregularly stuck to the web.
Consequently, a trimmin~ operation is necessary to cut away a
small amount of foam to thus give the bottom surface a smooth
and uniform appearance.
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9Z3
The present invention provides an improved apparatus
for manufacturing continuous blocks of polyurethane foam
which enables one to eliminate, during manufacture, the densi-
fied bottom of the blocks as well as surface irregularities
thereof.
More particularly, according to the invention there
is provided in an apparatus for obtaining continuous blocks of
polyurethane foam, which apparatus comprises a foaming tunnel
the lower part whereof is constituted by the conveying run of
an endless conveyor belt formed by a plurality of plate-like
cross members connected in hinged fashion and mounted between
end ~riviny and guiding wheels at the ends of the tunnel, the
improvement wherein a box-like housing surrounds the conveyor
belt, the housing having a bottom, vertical sides of a height
such that their upper edges are flush with the surface of the
conveying run of the conveyor belt over its entire lenght, and
vertical end plates, the end plate located on the upstream side
of the conveyor belt being of a height equal to that of the si-
des and the end plate located at the downstream side of tlle
conveyor belt being of a height le~s l.:harl that of the sides,
the bottom, the sides and the end plates are totally or par-
tially made of heat insulating material and the arrangment
is such that the conveyor belt is located inside the insulated
housing with the upper surface of its conveying run flush with
the edges of the sides and the upstream end plate, A cross
partition runs from side to side of the housing and along the
top between the lower and upper runs of the conveyor belt thus
dividing the space between the conveying and return runs of the
belt and between the sides o the housing into an upstream chamber
and a downstream chamber. The apparatus further includes first
heating means adapted to heat the conveyor belt and second
~126~Z3
heating means adapted to heat the surface of the bottom of the
block of foam downstream of the foaming tunnel
For a better understanding OL the improvements pro-
vided by the invention, a brief description will be given below
of the elements comprised by a standard apparatus for producing
blocks of polyurethane foam.
The basic elements or parts of a standard apparatus
are: a foaming tunnel constituted by a sloped conveyor belt,
formed by hinged plates, the floor of the foaming tunnel
being constituted by the upper run of the conveyor belt, the
rest of the parts of the tunnel is formQd by side walls and a
ce.iling providecl with conduits for evacuating the gases which
are formed and/or released during the reaction which results
in the foarn, such as C02 and blowing agent. In the upstream
part of the foaming tunnel there is mixer-feeder device, in
which the various reactants which forrn the foam are mixed
and from which they are fed onto a web, preferably paper,
which covers and t:ravels with the upper part of the conveyor
belt of the foamin~ tunnel. After the erldLess conveyor belt
of the foaming tunnel there are several draw.i.ng conveyors whi.ch
move the block formed in the foaming tunnel towarcl an arrange-
rnent of idle rollers, from which the block passes on to be cut
and stored.
The aforementioned paper web is interposed on the
upper surfaces of all the conveyor belts, being fed from a
supply device located upstream from the foaming tunnel and
being removed by a collecting device located downstream from
the last drawing conveyor and before the idle roller arrange-
ment. Naturally, i.n the apparatus there are also tanks for
reactants, pumps motors for actuating the conveyors and other
necessary devices for its operation.
{r~
.~
~Z6923
The improved apparatus of the invention essentially
ihcludes an enclosed insulated housing surrounding the conveyor
belt and means for heating the conveyor belt and the surface
of the bottom of the block of foam downstream of the foaming
tunnel.
In a preferred embodiment of the invention, there is
provided inside the box-like housing a plurality of cross
partitions running from side to side of the housing, the cross
partitions heing parallel to each other and perpendicular to
the backs of the upper and lower runs of the conveyor belts
and being capable of acting in two positions, the first of
which, called open, allows air to flow through them, and the
second, called closed, does not allow air to flow. During
the operation of the apparatus,-all the cross partitions are in
the open position except one, which is in the closed position,
thereby obtaining the formation of the two aforementioned
chambers, one being the upstream or reaction chamber and the
other the downstream or consolidation chamber, which chambers
are variable from one type of foam to another, the ~eparakion
between the two being formed by the parti~ion which is closed.
The number of cross partitions is preferably at least three.
This arrangement permits the obtaining of upstream and down-
stream chamhers having a given constant volume, but variable
from one foam to another. It is to be noted that, according
to this preferred embodiment of the invention, the formation
of these two chambers which are variable from one type of
foam to another may be used for all the heating means considered
herein and not only for hot air which constitute a preferred
embodiment of the invention.
According to another preferred embodiment of the
apparatus of the invention, the second heating means for heat-
1~269Z3
ing the surface of the bottom of the block of foam are located
at a place downstream of the foaming tunnel, between the
foaming tunnel and the first drawing conveyor, between two
drawing conveyors or between the last drawing conveyor and the
idle roller arrangement, the surface of the second heating
means being in contact with the web of continuous material
which covers the bottom of the block, which is rolled onto the
collecting means located downstream from the second heating
means.
According to a first preferred of the first heating
means used for heating the conveyor belt,such heating means
comprises hot air blowing means having an intake and an outlet
and located outside the housing. A main hot air supply
conduit is connected to the outlet of the blowing means and
passes beneath the housing. Two secondary conduits branch
off from the main supply conduit at a point located halfway
along the conveyor belt, each of the secondary conduits running
toward the respective ends of the housing. A p]urality of
bypasses is uniformly distributed over the en-tire length of
each secondary conduit. Adjustable opening outlets are pro-
vided at the end of each secondary conduit in their associated
chamber, on one of the sides of the housing. A plurality of
adjustable opening outlets, in each chamber, on the other side
of said housing, is likewise uniformly distributed over the
entire length of each secondary conduit. A plurality of outlet
conduits start from each of the air outlets. A first air
outlet collecting conduit is connected to the outlet conduits
from the upstream chamber and which goes toward the midpoint
of the length of the conveyor belt, and a second air outlet
collecting conduit is connected to the outlet conduits from the
downstream chamber and which also goes toward the midpoint
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~269Z3
of the belt, to meet there with the first collecting conduit
in order to form a single main air outlet conduit which is
connected in turn with the intake of the hot air blowing means,
so that closed circuit circulation of the hot air is obtained.
According to a second preferred embodiment, the first
heating means for heating the conveyor belt comprises a coil
arranged on two planes, an upper one located beneath and beside
the conveying run of the belt and a lower one located above
and beside the return run thereof. A source of steam under high
pressure and at high temperature is located outside the appa-
ratus and a steam conduit connects the steam source to the
coil for circulating steam through the coil.
~ ccording to a third preferred embodiment, the first
heating means for heating the conveyor belt comprises a plu-
rality of infrared radiation heating elements arranged on two
planes, an upper one where these elements are directed to
radiate heat toward the lower part of the conveying run of the
conveyor belt, and a lower one where the elements are directed
downward, to radiate heat toward the back of the return run of
the conveyor belt, all the heating e].ernents being uniformly
distributed over the entire length and breadth of the conveyor
belt. In this alternative embodiment, a partition runs hori-
zontally over the entire length and breadth of the belt, at
mid height, in the space, so that it divides the latter onto
an upper chamber and a lower chamber. There are further pro-
vided temperature sensing means in the chambers and a device
controlling the feed of electric power to the upper and lower
heating elements and actuated by the temperature sensing means.
According to a fourth preferred embodiment, the first
heating means for heating the conveyor belt comprises indivi-
dual electrical resistor elements incorporated in each of the
~Z69Z3
plate-like members which form the conveyor belt, duly insulated
therefrom to avoid faults through passing of electric power
to the belt. Two power supply tracks are arranged following
a trajectory which is adapted to the trajectory of the convey-
or belt over its entire contour, close to the edges of the
latter, and two current collection trolleys are provided, one
at each end of one of said plate-like members, each of which
trolleys slides in contact with one of the powersupply tracks.
Preferably, the apparatus of the invention further
comprises, in the upstream chamber, ventilation means which
operate when the temperature inside the chàmber exceeds a
preset maximum limit value.
With respect to the second heating means used for
heating the surface of the bottom of the block of foam, such
second heating means may advantageously comprise a rectangular
plate, the longer side whereof is equal to or slightly larger
than the breadth of the block of foam, there being arranged
to one side of the plate a housing in the longitudinal central
portion whereof there are arranged heat-generating means and
a temperature senc3ing-controlling device, and in which two
side longitudinal areas there are provided two cooling conduits,
one inlet conduit and another outlet conduit, which are provi-
ded with orifices which comrnunicate with the central part in
wh~h the heat-generating means are located, there being in
the inlet conduit to the cooling means an electrovalve connected
to a conduit which comrnunicates with a compressed air tank,
the electrovalve being of the type which opens when there is
an electric power cut.
According to one preferred ernbodiment, the heat-
generating means are constituted by infrared radiation elementsuniformly distributed in the housing, radiating heat toward
--8--
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69Z3
the back of the rectangular plate, the front side whereof is
in contact with the paper web, the feeding of the radiation
elements being connected and disconnected by the action of
the temperature sensing-controlling device.
According to another preferred embodiment, the heat-
generating means are constituted by a coil located in the
housing, which coil is fed by hot oil or steam, the amount
of heat being controlled by the position of an electrovalve
located in the inlet conduit, which is governed by the tempera-
ture sensing-controlling device located in the housing. The
temperature sen~ing-controlling device preferably also
controls the opening of the electrovalve located in the inlet
conduit of the cooling means.
The invention is illustrated by way of example in
the accompanyings drawings, wherein:
Fig. lA is a schematic elevational side view of
an improved apparal:us according to the invention, where
the conveyor belt is heated according to a preferred embodi-
ment of the invention, that is, by hot air~
Fig. lB is a plan view of the complete installation
of figure lA.
Fig. 2A is an elevational side view of only the
conveyor belt arrangement of the foaming tunnel of figure lA.
Fig. 2B is a plan view of the arrangement of
figure 2A.
Fig. 3A is an elevational side view of the conveyor
belt arrangement of the foaming tunnel, of the embodiment
according to which heating is effected by infrared rays.
Fig. 3B is a plan view of the arrangement of Fig. 3A.
Fig. 4A is an elevational side view of the conveyor
belt arrangement of the foaming tunnel, of the embodiment
g _
1~269Z3
according to which heating is effected by electrical resistors,
Fig, 4B is a plan view of the arrangement of Fig, 4A,
Fig, SA is an elevational side view of the conveyor
belt arrangement of the foaming tunnel of the embodiment
according to which heating is effected by coils through
which steam circulates.
Fig, 5B is a plan view of the arrangement of
figure SA.
Figs. 6A and 6B are cross-sectional views along
10 line A-A of Fig. 2A and along line C-C of Fig. 3A, respect-
ively, and show a front view of one of the aforementioned
cross partitions which are capable of acting in two posi-
tions, that is, open and closed.
Figs. 6C and 6D, respectively, are cross-sectional
views along lines B-B of Figures 4A and 5A, respectively, and
show a front view of one of the aforementioned cross partition
means, in the embodiments according to which heating is
effected by electrical resistors and coils with steam,
respectively.
Fig. 7 is a cross-sectional view along line D-D
of figure 6A.
Fig. 8 is a fragmentary view of a detail of the
arrangement shown in Figure 4A.
Fig, 9 is a cross-section view along line B-B of
Fig, 3A.
Fig, 10 is a fragmentary view of another detail of
the arrangement shown in Figure 4A.
Fig. 11A is a plan view of an embodiment of the
surface heating means for the bottom of the block which con-
stitute the second aspect of the invention.
Figs. 11B and llC are cross-sectional views along
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line A-A and along "B", respectively of Figure llA.
Fig, 12A is a plan view of another embodiment of
the surface heating means for the bottom of the block and,
finally
Figs. 12B and 12C are cross-sectional views along
line A-A and along " B" of figure 12A.
AS previously indicated, the process of Applicant's
aforementioned Spanish Patent No. 466,102, is carried out in the
improved apparatus of the present application. The process des-
cribed in this patent basically implies obtaining three differ-
ent heat levels on three surface areas of the installation which
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112695:3
are in contact with the web, preferably paper, which is placed
between the surface of the floor of the foaming tunnel and of the
drawing conveyors, and the bottom of the block of foam.
On the surface of the foaming tunnel, in a first re-
action area located upstream therefrom, a temperature TR, which
varies from one foam to another, is maintained throughout foam-
ing. The extent of said reaction area, which depends on the re-
activity of the formulation, likewise varies from one foam to
another. In Fig. lA of the drawings, 3, 4 and 5 identify the
slope of the growth curves of the foam for three formulations
of different reacl:ivity. The most reactive foam is that for
which the growth curve is identified as 3, whereas the least re-
active is that for which the growth curve is identified as 5.
Subsec~uently, a temperature Tc higher than TR is main-
tai.ned in a second s~lrface area of the floor of the foaming tun-
nel, called consolidation area. The value Tc is also kept con-
stant throughout foaming, varying from one foam to another. It
is readily realized that since the floor of the foan~ y tunnel
constitutes the reaction and corlsolidatioll areas, once the Eorm-
er is establishecl by the reactivity of the foam, the extent ofthe latter is obtained.
In Fig. lA o the drawirlgs, the longitudinal edges of
the reaction and consoliclation areas for the three type.s of foarn
would be as indicated in the following table:
. ._ .
REACTION CONSOLIDATION
AREA AREA
~IIG~I REACTIVIq'Y FOAM AB BF
. ! _
MEDIUM " FOAM AC CF
_ . . . ~
LOW " FOAM AD ¦ DF
'.~ "
12,
~1269Z3
The third area, called drying area, is downstream
from the foaming tunnel, between the foaming tunnel and the
first of the drawing conveyors 16, between two drawing conveyors
~a second conveyor is shown in Figure lA as 17), or between the
last drawing conveyor and the idle roller arrangement 25. There
may be more than one such area and it is always before the place
where the paper removing device 14 is located. In said area,
the bottom of the moving block E is subjected to a drying temp-
erature Ts much higher than TR and TC for a very short time.
The mentioned Fig. lA shows three of these drying areas as 22,
23 and 24.
Thus, the improved installation for manufacturing
blocks of polyurethane foam makes it possible to obtain
the three mentioned temperatures TR, TC and Ts, which
fullfil the condition TR < TC C~ Ts. Additionally, the
surfaces of the foaming tunnel where the first two men-
tioned temperatures are attained, that is, reaction are
(TR) and consolidation area (Tc), may vary according to
the reactivity of the foam.
The rema:Lning parts of the insta:Llation of Fig. lA are
as follows:
1 is the mixer-feeder head, 2 is a side wall of the
foarning tunnel, 13 is the paper web supplying device, 15 is the
conveyor belt of the foaming tunnel, formed by plate-like mem-
bers identified as P in Figure lB, 18 are conduits for evacua-
ting the gases formed and/or released during the reaction in the
foaming tunnel, such as C02, FREON (trademark), etc. RA is
the driving wheel of the conveyor belt 15 and RG is the guid-
ing wheel of the said belt. The remaining parts of the in-
stallation shown in Fig. lA will be defined hereinafter in
relation to other figures of the drawings where they also appear.
The elements of the improved arrangement of the convey-
n
- 13 -
6~23
or belt of the foaming tunnel which are common to the different
heating means and which are shown in Figures lA to SB are de-
scribed below.
Said conveyor belt 15 is surrounded by a large sized
heat insulated box-like housing 35, the upper surface of the
conveying run of said conveyor belt being arranged flush with
the open upper part of said box. Said box-like housing 35 is
formed by a bottom 10, locatecl at a very short distance from
the lower or return run of said conveyor belt 15, vertical sides
CVl and CV2, also located at a very short distance from the side
edges BL,l ancl ~L2 of said conveyor belt 15 and of a hei~ht such
that their upper edges are flush with the upper surface of the
conveying run of said belt over its entire length, and vertical
end plates PEl and PE2 located close to the end parts of said
conveyor belt 15. The plate located upstream from the belt,
that is, PE2, is of a height equal to that of said sides CVl and
CV2, whereas the plate PEl is of a height lesser than that of
said sides CVl and CV2. The parts formil-lg said llol~.qil)g 3~ aL
is, the bottom 10, ~he vertica1. ~;kla~ ~`V]. arl(l CV2, and the end
plates P~l and PE2 are totally or partiaJly made of heat insu-
lating material.
In the inside oE said hox, that is, the volume defirled
by said conveyirlg and return runs of the belt and between the
sides of said box, there are three cross separating partition
means 19, 20 and 21 capable of actiny in closed and open posi-
tions, only one being in the closed position during the operation
of the installation, the other two being in the open position.
Whatever the heatirly means may be, it is thus possible to form
the two upstream and downstrealn chambers, according to the termin-
ology used in the parent patent, or reaction and consolidationchambers, as indicated above, which may vary in volume according
to the reactivity of the foam which it may be desired to pro-
_ ~ _
duce. In fact, if it is desired to manufacture a high reacti-
vity foam the partition means 19 will be in the closed position,
whereas the partition means 20 and 21 will be in the open posi-
tion. When an intermediate reactivity foam is involved, the
partition means 20 will be closed, and 19 and 21 open. When a
low reactivity foam is involved, the partition means 21 will be
closed, and 19 and 20 open. ~aturally, only the partition means
which are closed will allow an airtight insulation between the
two chambers, thereby obtaining, with the programrned use of the
heating means, the two different heat levels on both sides of
the closed partition means, in such a way that the temperatures
Tl~ and 'l'~, are attained on the surface of the endless conveyor
belt. Said separating partition means, the positions whereof are
actuated by rod means 30, will be defined hereinafter in detail
in the explanation of Figures 6A, 6B, 6C, 7, 8 and 9.
Between the end plate PE2, close to the mixer-feeder
head 1, and the first separating partition means 19, on the side
CVl, that is, in a part of the upstream chamber which always
forms part of the reaction chamber, there i~ a fan ll, the mls~
sion whereof is to start operating and driv~ cold air lnto the
enclosure of the upstream or reaction chamber when a temperature
exceeding the programmed temperature TR is reached.
According to a preferred embodiment, the heating rneans
are constituted by hot air recirculated in a closed circuit from
an installation located outside the conveyor belt arrangement of
the foaming tunnel. This embodiment is shown in Figures 1~, lB,
2A and 2B.
Outside said housing 35 there are hot air blowing
means 12, the outlet whereof is connected with a main hot air
supply conduit 26 which, passing beneath the mentioned housing
35, subsequently branches-off into two secondary conduits 6 and
6' at a point located halfway along said conveyor belt 15, each
3B ~s- -
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~.
of said secondary conduits 6 and 6' running toward the respect-
ive ends of said housing, adjacent to the side. Starting from
each of said secondary conduits 6 and 6' there is a plurality of
bypasses G, at the outlet whereof there are air inlet control
valves 8, some of them ending in the reaction chamber and others
in the consolidation chamber, on the side CVl. Starting from
the opposite side, that is, CV2, there is a plurality of bypasses
G', at the outlet whereof there are air ou-tlet control valves 9.
Said bypasses G' are inserted in two air outlet collecting con-
duits 7 and 7', which meet at a point located halfway along saidconveyor belt, in order to forln a single main air outlet identi-
fi.e~ a9 27, whi~h is conrlected in turn with the intake of the
blowing means 12, thereby obtaining closed circuit clrculation of
the hot air toward the inside of the box and toward the outsicle
thereof.
At the ~oint where the mentioned main hot air supply
conduit 26 branches-off to form the secondary conduits 6 and 6'
there is a directing valve 29 which allows distribution o~ the
flow of hot air fed by th~ blowing means 12 to th~ ~e~pective
secondary f~eliny corlduits ~ all(3 6', equally or difEerently.
Li]cewise, at the polnt where the outlet collecting conduits 7 and
7' meet to form the collecting conduit 27 there ls another direc-
ting valve 2~, which performs a similar mission on the return
flow of air, the orientation thereof depending on that of the
aforementioned valve 29.
In F'ig. 2B the extrerne positions of said valves 29 and
2~ are shown as H, I, J and K, respectively.
The aforementioned fan ll is on the side CVl, in commu-
nication with the volume of the reaction chamber through a flow
control valve 31. On the opposi~e side CV2 there is an assembly
32 of air outlet means also provided with a flow control valve.
Said cooliny air inlet and outlet flow control valves can adopt
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l~Z~ 3
any position, between a completely closed and a completely open
position, operating in mutually dependent form when an excessive
temperature were detected in said reaction chamber, above a pre-
set limit value, which might be detrimental for the foaming of
the material on the conveyor belt 15, when said belt were to stop
as a result of a breakdown, for example.
Each sécondary conduit 6 and 6' for supplying hot air
to the inside of said housirlg 35 extends at its end part into
the conduits CEl and CE2 adapted to feed sai.d hot air to the in-
side of the mentioned housing through the end parts of the latter,said condui.ts b~ing provided with several hot air feeding outlets
(not shc)wn) distributed over the entire breadth of the correspon-
ding end plates PEl and PE2.
Inside said housing, at one point located to the left
of the separating partition means 19 and another to the right of
the separating partition means 21, that is, at places which are
always a reaction and consolidation area, respectively, there
are temperature sensing-controlling devices 3~ an(l 33, the m.i.s-
sion whereof i.s to colltrol the positioll of the vaL ve9 2~ al-ld 29
direcking the air outlet ~nd supply, as well as the position o.t
the valves ~ and 9. The sensor 34 can also actuate the fan 1l.
when the closing of the di.recting valve 29 and the valves ~ are
insuffi.cierlt to reduce the temperature of the reaction chamber
and it also becomes necessary to inject cold air.
Figures 3A, 3B and 9 schematically show a second embo-
diment of the invention, in which the upper and lower runs of
said conveyor belt 15 are heatecl by incorporating, inside said
volume, heating means constituted by a plurality of infrared ra-
diation heating elements arranyed on two planes, an upper one on
which sai.d elements are directed to radiate heat toward the lower
part of the upper run of said conveyor bel.t, and another lower
plane on which said elements are directed downward to radiate
/7
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~69Z~
heat toward the back of the return run of -the men~ioned conveyor
belt. In said Figures 3A and 9 the heating elements of the upper
plane of the reaction area are shown as 36, those of the lower
plane of said area as 40, the heating elements of the upper
plane of the consolidation area are shown as 50, and those of
the lower plane as 51. The elements 42 and 47 of the upper plane
may belong to the reaction or the consolidation area, depending
on which of the partition means 19, 20 or 21 is closed. Simi-
larly, the heating elements 41 and 52 of the lower plane may be-
10 long to the reaction or the consolidation area for the same rea-
son. As can be seen in the Figures, there is a dividing parti-
tion 37, 37a, 37b and 37c which runs horizontally over the entire
length of said belt, at mid height, in said volume, an upper
chamber and another lower one thereby also being obtained.
Nine temperature sensing-controlling devices 34, 38,
39, 43, 44, 45, 46, 48 and 49 can be seen in Figure 3A. The one
shown as 34, located in the r-eaction area, performs the same
mission as in the embodiment of figure 2A, that is, on detecting
a temperature value exceeding the programmed temperature Tl~ it
20 actuates the fan 11, injectlng cold air whlch run~ out through
evacuation means not ~3howrl in Fig. ~U. Those shown a~; 3~3, 43 and
45, located in the r-eaction area on the upper plane, will be
adjusted to connect and disconnect the heating elements 36, 42
and 47 to maintain t~he proyrammed temperature TR when the parti-
tion means which are closed are those shown as 21. Since the
sensors-controllers 43 and 45 may belong to the consolidation
area, according to which partition means 19 or 20 are closed,
their programming to TR or to T(~ will depend on the type of foam
produced. The sensors-controllers 39, 44 and 46, located on the
30 lower plane, are programrned to a temperature below TR because
when the means 19 and 20 are open the lower chamber, which is
known as the approach to the reaction area, requires a lower
~ .
~ 5
1~269;~3
temperature than TR. The same as those of nurr~ers 43 and 45, the
sensors-controllers 44 and 46 may belong to the reaction or the
consolidation area, depending on which of the means 19 or 20 is
closed, and their programming will thus depend on the type of
foam produced. The device 48 will connect and discc,nnect the
heatiny elements 50 to maintain the programmed temperature Tc.
The devices 43 and 45 will be equally adjusted in the event that
the closed means are those shown as 19. Finally, the device 49
will actuate the heating elements 51 to maintain an interrnediate
temperature between TC and TR on the surface of the return run on
the back of which the radiati.on falls.
l'he electric power points actuated by the sensing-
controlling devices are shown in Figure 3B. The device 3~ actu-
ates 53, the device 43 actuates 53', the device 45 actuates 54
and the device 48 actuates 55. The electric power points for the
heating elements 40, 41, 52 and 51 of the lower chamber are not
shown, but their location and operation will be readily realized.
As has been indicated, the device 34 only actuates the fan 11.
In the heating embodiment shown in ~'i.gure~ 4A, ~B and
10, said heating is effected by heatlng trlearls consti~uted by in-
dividual electric~l resistor elements R incorporated in each of
the plate-like members P forming the conveyor be.l.t. In this em-
bodiment said elemerlt~, R are d~tly insulated from the members P
to prevent faults through pa~sing of electric power to said belt
15.
Electric power is fed to each of said electrical resis-
tor heating elements R through an arrangement (see figure 10, en-
largement of detail L in Fig. 4~) which comprise.s two trolleys T,
one being arranged at each end of a member P of the conveyor
belt, each of said trolleys T sliding in contact with a power
supply track T', arranged following a trajectory which is adapted
to that of the conveyor belt over its entire contour, close to
~ 6 -
its edge parts.
In an alternative of this embodiment, said two trolleys
T are arranged at the same end of each of said members P of said
conveyor belt, in which case said power supply tracks T' are in
mutually adjacent arrangement, close to one or the other edge
of said conveyor belt, over its entire contour.
Apart from the separating partition means 19, 20 and 21,
said Figures 4A and 4B show the sensing-controlling device 3~
which actuates the fan 11, which drives cold air into the reac-
tion enclosure, said air running out through outlet means whichare not shown. ~s has ~een indicated earlier, this aspect is
col~non to the four ernbodinlerl~s of heating means considered.
Said figures likewise show four sensing-controlling devices 56,
57, 58 and 59. The first of them 56, actuates the feeding of the
resistors of the reaction area to connect or disconnect the elec-
tric power depending on the programmed temperature TR. Device
5g actuates the feeding of the resistors of the consolidation
area to maintain the programmed temperature Tc. The sensing-
controlling devices 57 and 5i3 beLong to the rerlctlon or the con-
solidation area dependirl~ orl which parti~ion means lg - 20 are
closed and, consequently, they will be programmed the same as 56
or as 59. Said resistor connecting-disconnecting points are
showrl as 60, 61, 62, 63, 6~ and 65.
Figures 5A and 5B show the embodiment according to
which the heating means are constituted by coil-like conduits,
inside which steam circulates under high pressure and at high
temperature, from a supply source outside the installation (not
shown). The mentioned figures 5A and 5B show the coils of the
reaction area 66, those located between the partition means 19
and 20, shown as 67, others located between the partition means
20 and 21, shown as 68, and those located in the consolidation
areas69. The inlet of steam to said coils is controlled by the
~- 2~
- 17 -
. ~
~6g~3
electrovalves 74, 75, 76 and 77, the positions whereof are con-
trolled by the temperature sensing-controlling devices 70, 71,
72 and 73. As can be seen, said stearn coils are arranged on
two planes, an upper one and another lower one, the coil sections
being located on each plane, respectively, close to the back of
the upper run of the conveyor belt and close to the back of the
lower run of said bel-t. Witl~ this arrangement, the output of
heat from the coils is distributed over the entire breadth and
length of the backs of said runs of the conveyor bel-t. Depending
on which partition means 19, 20 or 21 are closed, the electro-
valves 74, 75, 76 will. be programmed in such a way that the
sl:earn pass.i.ny throuyh ~hem E~ro(~ ces heat radiatiorl resulting in
Tl.~ or TC .
As has been indicated earlier, in the description of
the elements common to all the heating embodiments, in the embo-
diment which is being considered now the sensing-controlling
device 39 controls the operation of the fan 11.
A detailecl descri.ption is given below of one of the
cross separating partitiorllneans shown a.s 19, 2() or 21 .in Fi(lures
lA to 5B. Said de6criptiorl ;i.~5 Illade with re~er~ce to Fi~J~res 6A,
6B, 6C, 6~, 7 arld 8 >f the drawinys.
As has been indicated earli.er, figures 6A, 6B, 6C and
6D correspond to sections along the previously indicated lines
of figures 2A, 3~, 4A and 5A, respectively, and show a front view
of said ~separating partition means. Figure 7 is a cross-section-
al view of the parti-tion means of Figure 6A along line D-D of
said F`igu:re ~A. Figure 8 i.s a fragmentary view of the detail
identified as M in Figure 4A.
Said partition Ineans are constituted by two equal upper
and lower parts 78, formed by a rectangular metal plate or sheet,
the edges whereof are bent at right angles toward the same si.de,
forrning pairs of flanges 78a, directed toward the back of the
~ .
~;~Z69Z3
plates of the conveyor belt, the width of the flanges 78a being
relatively small in comparison with the width of the part 78
from which said flanges 78a project. A fork-like cross-sectional
part 78b is affixed from the longitudinal central halfway line
of the part 78, in a clirection parallel to and opposite said
flanges 78a. rrhis part 78b may be affixed to the rnain portion of
the part 78 by welding or by another mechanical means which
assures a perfect connection between both portions of sald part
78. Respective rectangular parts 79 of flexible plastic material
are connected to each of the flanges 78a. There are shutting
means 80 between the two parts 7~b, resting on the channel por-
l:ions ther:eof.
Said shutting means 80 are constituted by two juxta-
posed rectangular plates of sheet metal 81 and 82 (perpendicular
to the moving direction of the conveyor belt), which are provi-
ded with equal window-like openings, which are rectarlgular in
figures 6A, 6B, 6C and 6D, of a width approximately equal to
the distance between adjacent sides o two successivo windows,
although they rnay be of arlother shape. One ~f s.lid pla~es, that
showrl in Figure ~A of the drawirlg3 a9 81, can slide irl a direc-
tion perpendicular to the tunnel, being actuated by the rod
means 30. On the other hand, the other rectangular metal pLate,
that is, the one whose rectangular windows are represented by
dotted lines in the figures of the drawings, is of fixed position.
As can be seen in the drawings, the arrangement of said windows
of both plates, in alternating position, is such that there is a
position of the slidable metal plate 81, that called "closed",
which does not allow air to flow through the shutting means 80,
because the windows of both plates 81 and 82 are not in register.
Naturally, the "open" position, in which both windows of both
plates are in register, allows air to flow through them. It is
thus clear how tne "closed" and "open" positions of the partition
,~; 2~
means 19, 20 and 21 are attained. As has been indicated earlier,
only one of said three partition means will be operating in the
closed position, the other two being in the open position. The
mission of the parts 79, w~lich are of flexible plastic material,
as has been indicated, is to form airtightness on the two por-
tions, upper and lower, of said partition means. As can be seen
in Figure 7, said parts 79 of a resilient nature will be depress-
ed by the two short sides of the cross-section of the moving
plates P, recovering their position thanks to said resiliency,
thus forming substantially complete airtightness.
A descript:iorl is given below of -the su~ace drying
means, located downstream rom the foaming tunnel, and which are
shown in general as 22, 23 and 24 in Figure lA of the drawings.
The drying temperature TS for the bottom of the block of foam is
obtained in said surface drying means.
The description of said surface drying means will be
made with reference to figures llA, llB, llC and 12A, 12B, 12C.
The first three figures relate to an ernbodiment which use.s ln-
frared radiation elements a~ heatirlg meclrls, whereas the last
three figures reldte to arlother embodiment which uses steam coils
as heating means.
Said surface drying means, whatever may be the heatinc
means usec~, comprise the ollowiny parts: A smooth-surfaced
rectangular metal plate 83" the longer side whereof is equal to
or slightly larger than the breadth of the block of foam, a
housing N adjacent to one side of said plate 83, inside which
the means for heating and for cooling said plate are arranged.
Said housing is constituted by a shell 8~ and a heat insulation
~5. The longitudinal central portion of said housing ls consti-
tuted by the space in which the heating means are arranged, where-
as the end parts are occupied by -the cooling means. Said cooling
means are constituted by a cold air supply conduit shown as 86,
adjacent to one of the longitudinal edges of said housing and the
~ . .
side thereof adjacent to the central area occupied by the heat-
ing means is provided with orifices 91 which distribute the cold
air which enters throuyh said conduit 86 throughout the enclosure
of the heating means. On the side opposite said supply conduit
86 there is a collecting conduit 87, also provided with orifices
92, which evacuates to the outside the air which may have cooled
the enclosure of the heating means. The electrovalve 89 is at
the inlet of the conduit 86 and the electrovalve 90 is at the
outlet of the collecting conduit 87.
Said electrovalves 89 and 90 are of the type which
start operating when there is arl electric power failure. In this
specific case, during normal operation said valves would be
closed and as soon as there were an electric power cut they would
open, injecting compressed air, from an installation which is
not shown, into the enclosure of the heating means. The need
for said cooling means is imposed by the fact that the surface
drying of the bottom of the block of foam coated with the paper
web is caused by colltact of said bottom of the block mOvincJOve~r
the plate 83 heated by tho he;-lting means. As ha~ beerl indicated
~0 earl.ier, sa:id surface dryilly is causecl by a very high ternperature
applied for a very short time. Said time is that which the
bottom of the block of foam takes to cross the breadth of the
plate 83. If there is an electric power failure the whole in-
stallation stops, and although the feeding of the heating means
may also be cut off (which may not always occur), at the botto;n
of the block resting in contact with the plate 83 there would be
excessively high temperatures which could result in the combus-
tion of the foam. ~his risk is eliminated with the arrangement
of cooling means which has just been described.
Inside the enclosure where the heating means are locate~ ;
there is a temperature sensing-controlling device 88, the speci-
fic mission whereof will be explained in the description of the
.~
_ ~ _
,
~69~
heating means, contemplated in the embodiments shown in Figures
11 and 12.
In the embodiment of the surface drying means shown in
Figures 11 (A, B and C) heating is attained with infrared radia-
tion elements 93 uniformly distributed in the central part of
the housing N, which are fed from a source 94. In this embodi-
ment, on detecting a temperature value above the scheduled one
in the vicinity of the plate 83 the temperature sensing-control-
ling device 88 cuts off the feed 94, which is reconnected, by the
action of said device 88, when a value below the desired one is
reached. In this way, with the actiorl of said device 88, the
temperature TS on the plate 83 is controlled within the desired
range.
In a second embodiment of the surface drying mean~s
shown in Figures 12 (A, B and C), heating is attained with coils
95 through which steam or hot oil circulates. The feed oE the
fluid which circulates through said coils is controlled by an
electrovalve 96, located at the inlet of ~he coil contluit to ~he
heating enclosure. Fig. 12~ shows, a~ 97, th~ outl~ o said
coll from the heatirl(3 onclosuL-e.
As can be seen in Fig. 12A, in this embodiment the
sensing-controlling device 88 controls the operation of the elec-
trovalves 89 and 96. In Figure 12A the electrovalve 96 which
control~s the flow of hot fluid (steam or oil) has a mission
similar to that of the electric power supply source 94, for which
reason it is realized that both devices 94 and 96, with similar
missions, in both heating embodiments, are governed by the temp-
erature sensing-controlling device 88. However, in the embodi-
ment of Figure 12A the device 88 also governs the electrovalve
89, which will additionally start operating when there is an
electric power failure. This is due to the fact that the steam
coil system has more inertia and a slower response than the infra-
_ ,~ _
23
red ray system. It may thus occur that the device 88 senses atemperature TS above the desired one and orders the valve 9~ to
close altogether, but this may be insufficient owing to the iner-
tia of the system, for which reason the device 88 is also pro-
gramrned to actuate the electrovalve 89, allowing the intake of
cold air to cool the enclosure N.
In a third embodiment of the heating means, of the sur-
face drying means, not shown in the drawings, said heating means
are constituted by electrical resistors suitably arranged in the
enclosure N. However, this is the least preferred embodiment
because it is thc-~ one which present3 the greatest heat inertia
and wher:e ternperature control on the plate 83 is more difficult.
In the preceding description it is not intended to li-
mit the improved installation subject o~ the invention to manu-
facture only three types of foam, since all types, with their
corresponding reaction times,as well as the length of their
growth curve, are comprised within the three types which have
been mentioned above. In any event, the change in pOSit]OII of
the cross partition means 19, 20 and ~J cllso com-?s withlrl the
scope of the invention.
~; 'I G
