Note: Descriptions are shown in the official language in which they were submitted.
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PROCESS AND DOUBLE-BELT PRESS FOR THE CONTINUOUS PRODUCTION
OF BOARD MATERIALS
The invention relates to a process for the
continuous production of particle board and a double-belt
press for use in the process.
Such a process and such a double-belt press are
known, for example, from DE 21 57 746 C3 or DE 39 04 982 C1.
Provided in the press line are supporting plates, on which
the forming belts are supported via co-running roller
chains. The supporting plates are braced by strong bearers
which are arranged transversely to the track above and below
the respective supporting plates and are held together by
spindles outside the width of the track.
Provided in the supporting plates, extending
transversely to the track, are bores which form channels for
carrying a heat-transfer medium, generally a thermal oil.
The channels follow one another frequently in the direction
of travel of the track. Successive channels are
interconnected by U-shaped pipe elbows mounted at the edges
of the supporting plates, so that the heat-transfer medium
follows a zig-zag course transverse to the track, thus
improving the uniformity of the heat transfer. A plurality
of successive transverse bores in the direction of travel of
the track form a group fed in common with heat-transfer
medium.
In producing board materials, particularly
particle boards and similar materials, a substantial amount
of
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heat must be introduced into the feed material in the
first zone of the press line, in order to carry out the
curing reaction of the binder. In this context, the
moisture contained in the feed material serves to
transfer the heat into the material and plastify it. In a
downstream, i.e. subsequent, section situated toward the
end of the press line, the heat input no longer needs to
be so great, but rather, the primary concern here is the
maintenance of the spacing between the forming belts
perpendicular to the track for a given time during which
the material is cured, so that a calibrated board panel
emerges from the press line. By maintaining the thickness
in the downstream section, bonds which have been
introduced within the board material are not torn apart
again by premature relief of pressure befcre curing is
complete, which would weaken or even destroy the board
material.
In the installation known from DE 39 04 982 Cl, the
forming belts between which the board material is formed
are supported, rolling via roller chains, on the flat
supporting surface of a supporting structure located in
the press line above the upper forming belt and below the
lower forming belt. Even if the supporting structure is
no longer to be positively heated in the downstream
region of the press line, a substantial amount of heat is
transferred into the downstream section of the press line
by the advancing forming belts with the roller chains and
the web of board material.
Thus, a large part of the quantity of heat introduced
into the board panel in the first zone of the press line
is transported by the board panel, the forming belts and,
in particular, the roller chains into the downstream
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section of the press line, and is radiated there into the
surroundings, unused. Often no heat input is required any
longer for the board panel itself in the downstream zone of
the press line. On the contrary, it is sometimes even
desirable to already cool the board panel in the press to a
certain extent.
In order to have sufficient heat available in the
first zone of the press line, it is necessary to operate
there to an extent with an excess of heat which can no
longer be used in the downstream part of the press line, and
increases the energy costs.
The object of the invention is to reduce the
energy costs of an installation including the double-belt
press.
According to one aspect the invention provides a
process for the continuous production of particle boards
from board materials composed of particles held together by
a binder cured under heat and pressure in a double-belt
press, comprising the steps of: sprinkling particles that
have been provided with binder onto a horizontal run of a
conveyor belt to form a feed material; curing said feed
material under heat and pressure in a press line between an
upper run of a metallic, continuously circulating, lower
forming belt and a lower run of a metallic, continuously
circulating, upper forming belt, moving in synchronicity in
the direction of travel of the double-belt press to form a
panel composed of the board materials; transferring heat and
pressure necessary for forming in the press line from
supporting structure to the forming belts and thence to the
feed material, the heat being introduced into the supporting
structure by a heat-transfer medium conducted through
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channels therein; wherein the heat-transfer medium for a
downstream section of the press line is not heated, and in
this section, heat transferred to the heat-transfer medium
in the upstream region of the press line is extracted from
the heat-transfer medium and employed outside of the press
line.
Using the invention, the heat transported into the
downstream section from the upstream section by the board
material being formed, the two forming belts and the chains
can at least partially be kept from getting lost, thus
improving the heat balance in the overall installation. In
this context, there is also an additional effect which
improves the environmental compatibility of the operation of
the double-belt press: the extraction of heat from the heat-
transfer medium of the downstream section is synonymous with
cooling it. Thanks to the reduced temperature in the
downstream zone of the press line resulting from the
withdrawal of heat, the evaporation of formaldehyde
originating from the binder and the escape of other organic
vapors which can be inflammable, e.g. from waxes, are
reduced.
In many cases, it is possible to dispense with a
greater input, or even any input of heat in the downstream
section, since the forming belts with their higher
temperature continue to transport heat into the interior of
the board.
In a particular embodiment the heat extracted in
the downstream section of the press line is used at another
point in the process for manufacturing the board materials
themselves, for example, for pre-heating or drying the
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particles from which the panel of board material is formed,
or for heating water and/or thermal oil.
In another embodiment of the process, the heat
obtained in the downstream region of the press line can be
5 used, for example, for heating the factory installation in
which the double-belt press is installed, or even the
associated offices, that is to say, outside of the actual
board material manufacturing process.
According to another aspect the invention provides
a double-belt press for the continuous production of
particle boards and the like from board materials composed
of particles held together by a binder cured under heat and
pressure, comprising: an upper and a lower metallic forming
belt circulating continuously in a vertical plane, of which
an upper run of the lower forming belt and a lower run of
the upper forming belt overlie one another in a press line,
and are supported against supporting plates and press
together a feed material in the press line under the action
of heat and pressure to form a panel composed of the board
materials; channels provided in the supporting plates,
through which a heat-transfer medium can be conducted;
wherein the channels of a downstream section of the press
line can be supplied with unheated heat-exchange medium and
are connected to a heat exchanger in which heat extracted
from the heat-transfer medium of the downstream section is
transferrable to another assembly not belonging to the press
line.
In this connection, the "other assembly" in which
the recovered heat is employed can be the already mentioned
aggregate, upstream of the double-belt press, for forming
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5a
and pre-treating the feed material, or the heat exchanger
for warming water and/or thermal oil or a similar device.
In this context, the downstream section of the
press line is provided with completely unheated heat-
transfer medium.
In a specific embodiment there is the possibility
of utilizing the heat obtained in the downstream section of
the press line.
In another aspect for achieving the objective of
reducing the energy costs, the transfer of heat into the
downstream section of the press line is reduced in that, in
each case, a continuous roller chain or a group of such
roller chains side-by-side is not used for the entire press
line and for each forming belt, but rather, a chain
separation is carried out at a suitable location in the
press line, so that the first section of the press line has
its own roller chains and the downstream section of the
press line has further roller chains separate from them.
The portion of heat otherwise transported into the
downstream section of the press line by continuous roller
chains thereby remains largely in the first section of the
press line and does not become lost through the downstream
transport. A temperature drop of 20°C or more in the
downstream section of the press line can be achieved solely
by the separation of the roller chains. Meanwhile, the
first section of the press line can be kept at the necessary
temperature with a reduced application of heat.
Thus, according to this aspect there is provided a
double-belt press for the continuous production of particle
boards from board materials composed of particles held
together by a binder cured under heat and pressure,
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5b
comprising: two metallic forming belts circulating
continuously in a vertical plane, of which an upper run of a
lower forming belt and a lower run of an upper forming belt
overlie one another in a press line, are supported against
supporting plates and press together a feed material in the
press line under the action of heat and pressure to form a
panel composed of the board materials; channels in the
supporting plates, through which a heat-transfer medium can
be conducted; continuous roller chains co-advancing between
the forming belts and the supporting plates in the press
line and transferring the pressure and heat from the
supporting plates to the forming belts, and of which, roller
chains of a downstream section are separate from the roller
chains of a previous section of the press line which are
disposed on the same line in the direction of travel;
wherein separating points of the roller chains on at least
one side of the panel are disposed at an angle other than 90°
with respect to the direction of travel.
The chain separation in double-belt presses is
implied by itself from U.S. 4,334,468, however, in that
case, it is only from the aspect of being able to supply or
extract different amounts of heat to and from successive
sections of the press line in the direction of travel, but
not from the aspect of heat utilization.
In a double-belt press of another type, which is
used for drying fiber webs and is known from WO 97/39187,
one belt
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is heated with vapor and the other is cooled with water.
Running between the fiber web and the cooled belt is a
felt web into which the water condensed on the cooled
belt passes. The heat from the cool water is transferred
in a heat exchanger to another water which, with its then
increased temperature, can be used as process water in a
paper or cardboard machine.
The separation of the roller chain into a front section
and at least one following section also has significance,
independently of the question of the other use of the
heat recovered in the last section of the press line.
Namely, in this manner, gaseous components of the board
material can already be partially evaporated prior to
reaching the actual end of the press line. This applies
not only to water vapor, formaldehyde and the like, but
also to the combustible vapors mentioned, for example,
from waxes and the like used in the board material which,
if they are only able to emerge altogether in large
quantity at the actual end of the press line, have
already ignited there and led to fire accidents. In
addition, the mere reduction of the vapor pressure at the
separating point by partial discharge to the side, which
is possible due to the short-term "breathing out" of the
board panel as a consequence of the temporary absence of
the support of the forming belts at the separating points
and therewith accompanying reduction in the resistance to
flow for the vapor, has great practical significance,
just like the temperature reduction achieved in the final
section of the press line.
However, according to the present invention, the
separating points of the roller chains on at least one
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side of the panel are not disposed on a straight line
running at 90° with respect to the direction of travel,
transversely to the panel.
It may be that the separating points on at least
one side of the panel can be disposed on a straight line
which, however, runs at an angle other than 90° with respect
to the direction of travel; the angle can be different on
both sides, as well.
However, according to another embodiment, the
separating points do not need to lie on a straight line, but
rather - viewed in the direction of travel - can be in
different positions, so that the roller chain field is
jagged or lacerated, so to speak, at its boundaries situated
in the longitudinal direction. In this way, abrupt
alterations in pressure are avoided at one point - viewed in
the direction of travel - simultaneously over the entire
width of the panel.
In a particular design the successive roller chain
fields are, as it were, interlocked like a zipper.
Viewed in the direction of travel, the separating
point at the final section of the press line can lie at the
same point for the respective upper forming belts and for
the respective lower forming belts. However, then the upper
forming belt and the lower forming belt bulge simultaneously
outwards and there is a momentary "breathing out" of the
panel on both sides, which is unacceptable for the formation
and maintenance of the bonds developing in the panel.
An important refinement of the invention, both
with and without recovery of heat, is that the interruptions
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in the roller chains both sides of the panel are staggered
in the direction of travel of the panel.
This makes it possible to prevent the formation of
an outward bulge of the panel on both sides between the
forming belts, and the partial discharge of, for instance,
trapped gases can take place to an extent by increments,
first upwards and the other time downwards.
It is of no significance whether the separating
point in the roller chains of the upper forming belt is
situated ahead of or behind the separating point of the
lower forming belt in the direction of travel of the panel.
Experiments have shown that particle boards
produced according to the invention exhibit significantly
better technological values than particle boards produced
according to known methods.
Brief Description of the Drawings
Figs. 1 and 2 show longitudinal sections through
double-belt presses constructed according to the principles
of the invention;
Figs. 3 to 6 are schematic views from above of
different configurations of separating points in the roller
chains;
Figs. 7 and 8 are sections taken along lines
VII-VII and VIII-VIII, respectively, in Figs. 8 and 7 of a
separating point of the roller chains in enlarged scale;
Fig. 9 is a view, partially in section, of a
portion of an individual roller chain.
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Detailed Description of the Drawings
The double-belt press of Fig. 1, designated as a
whole by 100, is used for producing particle boards, wood
fiber boards and other board-like materials which are made
of particles bonded together by a binder which is cured
under heat and pressure. It includes an upper forming belt
1 of smooth closed sheet steel of approximately 2 to 3 mm
thickness and a similar lower forming belt 2. Between
forming belts 1, 2, a panel 4 made of a feed material 4'
composed of particle material provided with binder is
pressed together in a press line 3, resulting in one of the
aforesaid materials after pressing.
Upper forming belt 1 runs over rollers or drums 5,
6 arranged transversely to the panel and can be
hydraulically tensioned between these drums 5, 6.
Correspondingly, forming belt 2 runs over drums 11, 12,
arranged transversely to panel 4, which likewise produce
hydraulic tension of forming belt 2. Forming belts 1, 2 are
driven via the drums.
Forming belts 1, 2 run through the device in the
direction indicated by arrows 16. In press 3, lower run 1'
of upper forming belt 1 and upper run 2' of lower forming
belt 2 move in synchronicity and closely one upon the other
at a spacing which corresponds to the thickness of panel 4.
Feed material 4' deposited on the left side (as viewed in
the drawing) onto a conveyor belt, not
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shown, is drawn into press line 3 and pressed together
between runs 1', 2' of forming belts l, 2. From the
conveyor belt, feed material 4' passes over onto a
rolling tray 7 which transfers the feed material to lower
forming belt 2 shortly before the highest point of drum
11. The emerging, ready-pressed and cured panel 4 of
board material is cut up on the right-hand side of the
drawing by suitable devices, not shown, and transported
away.
Provided in press line 3, in the inner region of forming
belt 1 above its lower run 1' is an upper supporting
structure 17 which co-operates with a lower supporting
structure 18 provided in the inner region of lower
forming belt 2 underneath its upper run 2'. Supporting
structures 17, 18 brace the regions of forming belts 1,2
which face panel 4, against panel 4, and press them
together with great force.
Supporting structures 17, 18 are each made of individual
bearers 19, 20 which, in each case, are arranged in pairs
lying one above the other above and below forming belts
1, 2 and panel 4. Each pair of bearers 19, 20 is clamped
together by strong spindles, not shown, situated
laterally outside of press line 3, so that individual
compression members are formed that are self-contained
force-wise.
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Between bearers 19, 20 and forming belts 1, 2 are strong
supporting plates 26, 27 which transfer the force exerted
by individual bearers 19, 20 in a planar manner to
forming belts 1 and 2 and thus to panel 4. Supporting
plates 26, 27 have through-channels over the width
running transversely to panel 4, through which a heat-
transfer medium can be conducted. The channels closely
follow one another in direction of travel 16 and are
interconnected at the ends by pipe elbows, so that a
shared heat-transfer medium flows through groups of
channels in a meandering path.
Arranged between the mutually facing sides of supporting
plates 26, 27 and forming belts 1, 2 are roller chains
30', 30" upon which forming belts 1, 2 roll on supporting
plates 26, 27, the roller chains orbiting continuously in
a vertical longitudinal plane around supporting plates
26, 27 within forming belts 1,2. The rollers of roller
chains 30', 30" transfer both the pressure and the heat
from supporting plates 26, 27 to forming belts 1, 2 and
thus to panel 4 which is forming. Therefore, forming
belts 1, 2 experience a purely rolling support in press
line 3.
Press line 3 is split into two sections 3' and 3" which
follow one another in direction of travel 16 of panel 4
and which also have separate supporting plates 26', 27'
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follow one another in direction of travel 16 of panel 4 and
which also have separate supporting plates 26', 27' and 26",
27", respectively. In first section 3', heat is fed to
supporting plates 26', 27' by the heating of the heat-
s transfer medium, the heat giving rise to vapor generation in
compressed feed material 4' that contains a certain amount
of moisture. The vapor develops first near forming belts 1,
2, because they exhibit the highest temperature, and spreads
in feed material 4', causing rapid heating of the entire
volume of feed material 4' (steam impact) and thereby the
curing of the binder present in it. The heat-transfer
medium, for example a thermal oil, is heated in a heat
exchanger 40 and circulated, so that the most recently
heated transfer medium is supplied in the direction of arrow
41 at the start of first section 3' and is removed again
from the channels in supporting plates 26', 27' in the
direction of arrow 42 at the end of the first section, and
fed back in a closed circulation into heat exchanger 40. As
illustrated, the heat exchanger, on its part, can be acted
on by a further heat-transfer medium heated in a heating
aggregate 43 having registers 44, or else can itself contain
the heating.
In downstream section 3", i.e. the following
section of press line 3 in direction of travel 16 of panel
4, the mechanical pressure must be maintained until the
binder has cured and the vapor pressure is sufficiently
reduced, since otherwise the bonds just formed in the binder
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apart again. Circulating through supporting plates 26",
27" of this section is likewise a heat-transfer medium,
such that it is fed at the start of section 3" in the
direction of arrow 51 and removed again at the end of
section 3" in the direction of arrow 52.
Here as well, the heat-transfer medium flows through a
heat exchanger 50, in which, however, no heat is supplied
to it, but on the contrary, a part of the heat supplied
in first section 3' and reaching downstream section 3"
through the movement of forming belts 1, 2 and panel 4 is
extracted again. The extracted heat relieves the vapor in
panel 4 and thus reduces the vapor pressure prevailing
therein.
The heat extracted in heat exchanger 50 is used in a
separate assembly 53, not connected directly to press
line 3 and indicated only symbolically in the drawing, be
it for heating purposes, or be it used at a point prior
to the process sequence on the left-hand side of the
drawing for heating the particles, for drying the
particles, for heating water and/or pre-heating thermal
oil or for similar purposes. In this way, the heat
balance of the overall installation is improved and there
is also a benefit to the environment, in so far as the
escape of substances such as formaldehyde and the like is
reduced due to the lowering of temperature and vapor
SUBSTITUTE SPECIFICATION
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pressure in the final region of press line 3.
The channels formed in the supporting plates transverse
to panel 4 can be variably connected in groups following
one another in direction of travel 16. Accordingly, the
circumstance that heat is exclusively removed in section
3" of press line 3 is a feature of the exemplary
embodiment; however, it is entirely possible to envision
mixed forms in which a certain amount of heat is still
supplied at the beginning of section 3" and it is only
completely at the end that it is cooled, i.e. heat is
extracted.
A further heat-transfer medium which is not heated can
also be conducted through second section 3" if supporting
plates 26, 27 and roller chains 30 are formed
continuously over the entire length of press line 3.
However, in the exemplary embodiments shown in Figs. 1
and 2, sections 3', 3" are largely separated from one
another not only with regard to their supply with heat-
transfer medium, but also mechanically and from the
standpoint of heat conduction. Namely, in first section
3', the separate supporting plates 26', 27' already
mentioned lie opposite one another above and below panel
4, reach from the inlet up to separating points 28, 29 at
the end of first section 3' and are orbited by associated
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continuous roller chains 30', as will be described later
with reference to Fig. 9, and of which a number, for
example 40, run over the width of panel 4 directly side-
by-side but independently of one another in the direction
of arrows 16 in press line 3, and which together form a
roller chain field which is shearable in its plane in
direction of travel 16.
In Fig. l, supporting plates 26", 27", separate from
supporting plates 26', 27', start at separating points
28, 29 and extend to the end of press line 3, i.e. to the
end of downstream section 3" of the press line, and are
orbited by their own roller chains 30". Separating points
28, 29 at which forming belts 1, 2 pass from first
section 3' into downstream section 3" are only made as
short in direction of travel 16 as is constructionally
possible. However, because of the necessary reversal of
direction of roller chains 30', 30" over a radius, the
unsupported sections at separating points 28, 29 cannot
be made arbitrarily short, and amount to approximately
150 mm, which still has no effect on the loss of the
board material. Numeral 28 designates the separating
point between roller chains 30', 30" above panel 4, i.e.
for forming belt 1, 29 designates the separating point
for roller chains 30', 30" below panel 4, i.e. for
forming belt 2. Separating points 28, 29 lie on straight
lines running transversely to panel 4, i.e. all roller
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_ -
chains 30' and all roller chains 30" are in each case
reversed in direction in the region of supporting plates
26', 27' and 26", 27", respectively, at the same points -
viewed in direction of travel 16 - around the edges of
supporting plates 26', 27' and 26", 27"
Due to the separation at separating points 28, 29,
upstream roller chains 30' remain wholly in first section
3' and cannot transfer any heat into downstream section
3".
The heat which nevertheless reaches the downstream
section through forming belts 1, 2 and panel 4 during
steady-state operation is partially extracted in heat
exchanger 50 from the heat-transfer medium flowing
through supporting plates 26", 27" and supplied for
further use.
In embodiment 100 in Fig. 1, viewed in direction of
travel 16 of panel 4, separating points 28, 29 lie one
above the other at the same point.
However, in exemplary embodiment 200 in Figure 2,
separating point 28' for roller chains 30', 30" of upper
forming belt 1 is offset in direction of travel 16 with
respect to separating point 29' of lower forming belt 2.
Therefore, 28' and 29' do not lie one above the other,
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but are spaced in direction of travel of panel 4 by an
amount which is at least so large that a short stretch 25
remains between separating points 28' and 29', in which
panel 4 is supported by roller chains 30', 30" from both
sides, as in the remainder of press line 3. The direction
of the offset plays an insignificant role. It is only
important that the unsupported sections above and below
do not lie at the same point, and that vapors of all
kinds can be discharged from the board material not all
at once, but rather in two steps.
Incidentally, apart from the heat recovery which is just
omitted in Fig. 2, the exemplary embodiments of Figs. 1
and 2 are otherwise in agreement. This is intended to
illustrate that the separation of the chains can have
significance even without heat recovery.
Figs. 3 through 6 schematically depict various
configurations in the region of separating points 28,
28', 29, 29'. Only ten side-by-side roller chains 30',
30" are indicated in each case, although the number over
the total width of panel 4 is actually generally
substantially greater.
Fig. 3 shows the standard situation in which separating
point 28 runs along a straight line 31 extending
transversely to panel 4, i.e. perpendicular to direction
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of travel 16. Above and below panel 4, separating points
28, 29 can lie one above the other as illustrated in Fig.
1, but they can also be staggered in the direction of
travel, as indicated at 29' in Fig. 3 and represented in
Fig. 2.
According to Fig. 4, separating point 28 can also extend
along a straight line 32 which makes an angle other than
90° with direction of travel 16. Here as well, separating
points 28, 29' above and below panel 4 can either lie
directly one above the other or adopt different angles
from one another, as shown in the drawing.
The configuration shown in Fig. 5 differs from those of
Figs. 3 and 4 in that each roller-chain pair 30' 30",
lying on the same longitudinal line has, so to speak, its
own separating point, and that the separating points of
adjacent roller chains are staggered in direction of
travel 16. Thus, the separating points of individual
roller-chain pairs 30', 30" intermesh like a zipper. As
indicated by broken line 33', this configuration can also
have an offset in the longitudinal direction above and
below panel 4.
According to Fig. 6, the configuration with roller-chain
pairs 30', 30" intermeshing like a zipper can also form
over the width of panel 4 a separating zone along a line
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34 which adopts an angle other than 90° with respect to
direction of travel 16.
The embodiment of Fig. 5 is further explained with
reference to Figs. 7 and 8. The edges of supporting
plates 26', 26" adjacent in direction of travel 16 are
rounded off, so that roller chains 30' and 30",
respectively, pass around this radius and are conducted
upwards out of the region of engagement with forming belt
1, as can be seen in Fig. 8.
The rounded-off, mutually facing edges of supporting
plates 26', 26" do not lie on a common straight line, but
rather each individual roller chain 30', 30" has its own
pair of rounded-off edge regions 35, 37 and 36, 38,
respectively, each of which is only as wide as roller
chain 30' or 30". Furthermore, on supporting plate 26'
are edge regions 35 projecting in direction of travel 16,
and in between in each case is a set-back edge region 36.
In the case of supporting plate 26", lying opposite
projecting edge region 35 of supporting plate 26' is an
edge region 37 disposed further ahead in the direction of
travel, while edge region 36 of supporting plate 26' is
assigned a further set-back edge region 38 of supporting
plate 26". In this context, edge regions 38 engage
between adjacent edge regions 35, 35, so that the chain
fields of supporting plates 26', 26" are interlocked like
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!~ O
_ _
a zipper. In the exemplary embodiment, the spacing of the
forward edges of edge regions 35 and 36 - viewed in
direction of travel 16 - corresponds according to size to
the width of an individual roller chain 30' or 30". The
same applies to edge regions 37, 38, because distance 39
between the mutually opposite regions of roller chains
30' and 30" in direction of travel 16 is always the same
for side-by-side roller chains 30' and 30".
Fig. 9 shows the construction of an individual roller
chain 30', 30". Each roller chain 30, 30" includes three
side-by-side rollers 68a, 68b and 68c per chain pivot 65,
between which extend lines of links 61 and 62 having
straight links 61a, 61b, 61c and 61d. However, these
links are not provided one behind the other in a "lane"
parallel to direction of travel 16, but a given number
are offset one behind the other to the same side, and
after a predetermined number of links, the direction of
offset is reversed. Thus, for example, link 61a is offset
upwards with respect to link 61. Link 61b is again offset
upwards with respect to link 61a. However, link 61c is
offset downwards again with respect to link 61b and is
followed by four further links, each offset downwards, up
to link 61d, from which, in the drawing to the right, an
upwards offset takes place again. Therefore, string of
links 61 formed by the totality of links 61a, 61b, 61c,
and 61d takes a zigzag course within roller chain 30',
SUBSTITUTE SPECIFICATION
CA 02322418 2000-09-08
2j
30", so that the joints left by any two rollers is
overlapped by some of the following rollers.
Allocated to line of links 61 is a correspondingly formed
line of links 62, whose links are offset with respect to
the longitudinal central plane of roller chain 30', 30"
in the opposite direction to line of links 61. As already
mentioned, each member of roller chain 30', 30" includes
three rollers 68a, 68b and 68c which alter periodically
in their width and which, taken together, make up an
individual roller chain having mutually parallel, lateral
boundary faces 63 and 64. The three rollers 68a, 68b and
68c of a chain member are held together by a roller pin
65 whose head 66 is accommodated in a countersink 67 and
which does not project beyond boundary surfaces 63 and
64.
Mutually adjacent roller chains 30', 30" abut against
each other with their end faces 63 and 64, so that no
significant spacing remains at these locations, and
pressure and temperature are transferred essentially
uniformly to forming belts 1, 2 via the entire chain
surface. The joints between the individual rollers on a
roller pin 65 are periodically rolled over by rollers of
subsequent roller pins 65, resulting in an essentially
uniform engagement of the pressure transfer surfaces in
press line 3.
SUBSTITUTE SPECIFICATION
