Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
13~
~ Process and device for aPplyinq marking lines to a web
of mineral fibre containing a bindinq aqent
The invention concerns a process for applying mark-
ing lines to a web of mineral fibre containing a binding
agent, in accordance with the characterising clause of
Claim 1.
Such a process is known from DE-OS 32 29 601. The
marking lines to be applied there run in a longitudinal
direction along the mineral fibre web, i.e. in the di-
rection in which it is transported or produced. To avoid
applying dye with a relatively complex application tech-
nique, using a large amount of material, and possible
influencing the fire behaviour, a brand mark is produced
by directing a tightly bunched flame or a tightly
bunched jet of hot air at a temperature of 600C, for
example, at the surface of the web of mineral fibre,
which in its core area heats up the binding agent on the
surface of the web of mineral fibre until it reaches its
disintegration temperature, thus scorching it. To pro-
duce a continuous longitudinal marking line parallel to
the edge of the web, it is thus only necessary to ar-
range a corresponding hot-air jet or lance of flame over
the running web of mineral fibre.
Such a process is, however, limited to applying
marking lines parallel to the edge; to produce marking
lines running vertically to the side edges, it would no
longer be possible for the hot-air jet or the like to be
arranged in a stationary position, but instead it would
have to travel across the web of mineral fibre at an
angle, and at the same time it would have to be moved
with the web of mineral fibre; this, however, would
require highly complex plant engineering and control
techniques in particular if definitive and constant dis-
tances between the markings were to be achieved. Fur-
thermore, such a flame or jet of hot air does not only
cause the binding agent to disintegrate on the immediate
surface area alone, but unavoidably also produces a not
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inconsiderable deep action. In this way, a zone is cre-
ated which penetrates to a greater or lesser depth into
the web of mineral fibre, and in which no binding agent
is effective. This does not cause any harm in the case
known in the art, since this zone runs horizontally
along the web and is thus not exposed to any forces
acting crosswise to the direction of the marking line.
Since such webs of mineral fibre are às a rule wound up
into a roll and are stored and transported in roll form,
forces occur on any zones with no binding agents lying
crosswise to the longitudinal extension of the web of
mineral fibre: if the marked side is outside in the
roll, the material tends to gape open at the marking
line, whereas if it is inside, the material tends to be
compressed. This can lead to a weakening of the product
as a result of a partial disintegration of the fibre
compound in the region of the marking line in the case
of tensile forces, or increased flexing work in the re-
gion of the marking line when pressure is applied. Such
a weakening is undesirable, particularly when after the
roll is opened the material is supposed to have a homo-
geneous, slab-like consistency, which is the case ac-
cording to the parallel German patent application No. 36
12 858.9-25.
From DE-OS 34 46 406, the principle is known of
using a cylinder as the heating device. This heating de-
vice in the form of a cylinder is not, however, used to
apply marking lines, but to produce tack points that
penetrate deep into the material of the web of mineral
fibre, by locally softening the mineral fibres and thus
fusing them together. For this purpose, the surface
around the circumference of the cylinder has rows of
openings through which the hot gas escapes like a lance
at high temperatures of up to 1,000C as a rule. The
surface around the circumference of the cylinder rests
on the surface of the web of mineral fibre, and the cyl-
inder rotates at a speed corresponding to the transport
speed of the web of mineral fibre. Hot gas is only per-
_, . . . . .
mitted to escape from a row of holes when the latter are
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in the region of the lower apex of the cylinder, so that
the hot gas proceeding from each opening penetrates the
web of mineral fibre like a lance and forms tack points.
The depth of penetration here can be increased by cre-
ating a partial vacuum on the opposite side of the web
of mineral fibre.
Such a device is not used for applying marking
lines, nor is it appropriate for producing marking lines
which practically have no influence on the behaviour of
the mineral fibre material at the marking point. While
it is possible to reduce the great depth of penetration
that is desired in this known case by restricting the
supply of hot gas, it is nevertheless considerable in
every case when so much energy is to be applied by a
local flow of hot gas during the contact time as to pro-
duce a deep discolouration. Furthermore, it is difficult
to control the lateral limit of the area in which the
hot gas is effective, particularly in view of the fact
that the effect is produced while the cylinder is rotat-
ing, which means that it changes direction. Precisely
when the hot gas is flowing with a restricted throughput
in order to reduce the depth of penetration, lateral
flows become important, because they also produce a par-
tial disintegration of the binding agent near the edge
of the marking, and thus lead to a blurred delimitation
of the marking.
Proceeding from the state of the art as per DE-OS
32 29 601, the invention is based on the task of creat-
ing a process and a device which make it possible to
apply marking lines to a surface of a web of mineral fi-
bre, running at right angles to the edges, in as simple
and reliable a manner as possible, and which make it
possible to apply clearly delimited marking lines at
precise and constant distances from one another, while
keeping the depth of penetration of the disintegration
phenomena low.
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This task is solved from the point of view of pro-
cess technology by the characterising features of Claim
1, and from the point of view of the device technology
by the characterising features of Claim 6.
For this purpose, resort is first had to the con-
cept of using a cylinder in accordance with DE-OS 34 46
406, resting on the web of mineral fibre. Instead of us-
ing hot gas for the local disintegration of the binding
agent, however, the surface of the cylinder is heated
locally. Such a clearly delimited area of heat in the
form of a line parallel to the axis, with a correspond-
ingly higher temperature, produces a heating effect on
the mineral fibre material mainly by conduction, with a
correspondingly sharp fall in temperature penetrating
into the heat-insulating mineral fibre material, so that
the area of disinteqration remains restricted to a shal-
low surface region. Furthermore, towards the sides, the
heating effect also falls sharply, especially since it
is possible to cool the material by means of the unheat-
ed neighbouring areas on the surface of the circumfer-
ence of the cylinder, which produces a sharply delimited
outline. Since the heating areas around the circumfer-
ence of the cylinder are constructed at fixed intervals,
and since the web of mineral fibre and the circumference
surface of the cylinder travel at synchronous speeds,
the marking lines produced are always the same distance
apart. However, depending on the gearing relationship
between the cylinder and the surface of the web of min-
eral fibre, the distances between the marking lines pro-
duced on the web of mineral fibre can deviate slightly
from the distances between the heating areas on the cir-
cumference surface of the cylinder; such a deviation
between two neighbouring marking lines can hardly be
measured, but over a number of marking lines, it can add
up to a size that is relevant if, for example, the 20-
fold nominal distance between the marking lines is to be
determined by counting off 20 marking lines: here, in-
stead of the theoretical figure of 20 x 100 mm = 2 m, a
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deviating distance of 1.96 m, for example, could be re-
corded. In order to exclude even these deviations, which
though minimal nevertheless add up to relevant values,
the cylinder can be rotated at a circumference speed
that deviates slightly from the speed at which the web
of mineral fibre is travelling, so that in this way such
minor imprecisions can be compensated for by the layout
between the cylinder and the web of mineral fibre.
Since the energy drain from the heated areas is
restricted to the amount necessary to produce a dis-
integration of the binding agent over a clearly limited
local area and only in a shallow layer of the surface,
the energy consumption is kept to a minimum.
In a particularly practical version of the inven-
tion, the cylinder is pressed into the surface of the
web of mineral fibre in accordance with Claim 2, in or-
der to form a depression. The concomitant contact pres-
sure results in an improvement in the conductive heat
transfer from the heating area to the mineral fibres.
Furthermore, the fact that the impression results in the
formation of a depression means that the contact time
between the heating area and the mineral fibres is leng-
thened, which likewise improves the heat transfer. In
this way, when the web of mineral fibre is travelling at
a certain speed, the heat transfer can be adapted to
what is needed in order to form a clear mark, without
applying too much heat to the web of mineral fibre: at a
very slow transport speed, the cylinder is only pressed
against the web with a slight pressure, which reduces
the contact pressure and contact distance, so that the
desired amount of heat is applied, taking into conside-
ration the relatively long contact time that is avail-
able in the case of a slow transport speed, whereas at a
high transport speed, the amount of heat transferred in
the short time available is correspondingly increased by
raising the contact pressure and lengthening the contact
distance. Since it is practical to apply the marking
already on the production line, the speed of which is
dictated by the production conditions, this means that
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there is such a degree of freedom in adapting the mark-
ing conditions to the respective production speed that
whatever production speeds occur, there is a sufficient,
but not too great application of heat to the web of
mineral fibre. It goes without saying that the amount of
heat applied to the web of mineral fibre can also be
influenced - completely or additionally - by controlling
the temperature of the heating areas. However, bearing
in mind the heat load on the cylinder on the one hand,
and the heat load on the web of mineral fibre at the
contact point with the heating areas on the other hand,
there is a relatively narrow ideal temperature range,
which should be maintained if at all possible. By ad-
justing the depth to which the cylinder penetrates the
surface of the web of mineral fibre, it is possible cor-
respondingly to adapt the amount of heat applied, with-
out the temperature of the heating areas having to leave
the ideal operating range.
Especially when there is a fixed given production
speed for a particular web of mineral fibre with a con-
stant bulk density and a constant binding agent content,
and also when the transport speed of the web of mineral
fibre can be selected freely, there may be no need to
adapt the amount of heat applied to varying conditions,
or if it only needs to be adjusted within a narrow
range, this can be done by controlling the temperature
alone. In such a case, it is possible to construct a
particular~y simple version of the device by having the
cylinder pressing on the web of mineral fibre under its
own weight. Measures to vary the weight support during
operation can be made unnecessary if the weight of the
cylinder is adapted to the given transport speed, or if
the latter is adapted to the weight of the cylinder. If
necessary, the effective weight of the cylinder can be
reduced to a desired level by using a counterbalance.
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The measure described in Claim 4 likewise makes it
possible considerably to simplify the constructive
design of a device necessary to implement the process,
since no drive unit is needed in operation, and the most
that is required is a simple drive unit to pre-heat the
cylinder when it is in a raised inoperative position, in
order to ensure that the heating areas arranged around
the circumference of the cylinder are heated up evenly.
Using the measure described in Claim 5, broken
marking lines - dotted lines, as it were - can be pro-
duced. As a rule, these fulfil their purpose and make it
possible to work with individual shorter heating areas
placed at a distance from one another, which, in view of
their smaller extension, avoid problems that might oc-
cur, for example, when the heat expansion adds up in a
longitudinal direction. In addition, the energy consump-
tion is reduced and any impairment of the consistency of
the material as a result of tensile or pressure loads on
the fibres in the roll is avoided because of the fact
that there are sections of completely uninfluenced mate-
rial.
A device that is especially suitable for implement-
ing the process according to the invention is distin-
guished in detail by the characterising features of
Claim 6. Here, heating elements constitute a particular-
ly convenient constructive method of creating the heat-
ing areas necessary according to the process. To create
straight marking lines, heating elements running in a
straight line can be used; however, it is also possible
to create other marks, such as grids, monograms or the
like, if the heating elements are shaped in accordance
with the outline of the mark required in each case.
By using the measures described in Claim 7, energy
losses by heat radiation or heat conduction from the
heating elements are reduced to a minimum; at the same
time, the fact that the heating elements are enclosed
especially around the edges in the material of the
h
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mounts, which has good heat-insulating properties, re-
sults in a sharp delimitation of the heating areas and
ensures that the marking lines have clean edges.
If in accordance with Claim 8 the heating elements
stand out a short distance from the surface of the cir-
cumference of the cylinder, the air surrounding the
heating elements cools down the mineral fibre material
bordering the marking strips during the marking process,
which helps to produce clean edges to the marking lines.
Furthermore, especially when the cylinder is impressed
more deeply into the web of mineral fibre, the driving
effect of the mineral fibre material on the cylinder is
increased, since protruding edges of the heating ele-
ments encourage the driving effect.
If in accordance with Claim 9 the heating elements
can be heated by means of electrical tubular heating el-
ements, this provides considerable constructive freedom
in designing the heating elements. A tubular heating
element which is available commercially can be used; it
is then possible to achieve low acquisition costs and
high operating reliability, without its outer shape
limiting the freedom of construction for the heating
elements. In principle, however, any kind of suitable
heating device can be used, including a unit that works
without contact, i.e. by induction, as long as it is en-
sured that the desired heating can be produced locally
in the heating areas.
A particularly practical version of the construc-
tion can be produced in accordance with Claim 10 by
using an internal support frame for the cylinder in the
form of a cylindrical polygon. Using a simple method of
construction, each straight surface of the polygon can
be a support for the mount and the fittings of a heating
element.
The driving speed of the cylinder can easily be
synchronised with that of the conveyor or production
line by using a d.c. motor to drive the cylinder. If,
however, in accordance with Claim 4 the cylinder is
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caused to rotate as a result of being transported by the
web of mineral fibre, then in accordance with Claim ll
it is more practical to use an electric motor in the
form of a three-phase current motor, with a free-wheel-
ing system, which ensures that the cylinder rotates at a
continuous slow speed during the heating-up phase, at an
uncritical number of revolutions so that the heating
elements are heated up evenly, its free-wheeling system
means that the motor can be overtaken as soon as the
cylinder is pressing on the web of mineral fibre and is
driven by the latter at a higher speed. Every time the
operations are interrupted, the electric motor then
continues to turn the raised cylinder in order to ensure
that the heating elements always heat up evenly.
In particular when the cylinder is impressed into
the web of mineral fibre with varying force in accord-
ance with Claim 2, to adapt it to different transport
speeds of the web of mineral fibre, Claim 12 provides
for the position of the cylinder's bearing mount to
remain positively adjustable by means of a variable ad-
justing pinion. In this way, it is possible at all times
precisely to adjust the degree of impression of the cyl-
inder on the web of mineral fibre, in such a way that
the markings are formed optimally, depending on the
transport speed of the web of mineral fibre at any par-
ticular time.
It is appropriate for the adjusting pinion to have
at least one threaded spindle in accordance with Claim
13, which can be driven for example by means of an elec-
tric stepping motor, in order to guarantee that an un-
problematic precise adjustment by remote control can be
achieved and maintained. It is best for the threaded
spindles to engage in a supporting mount for the bearing
mount, which like the bearing mount can be raised and
lowered. In accordance with Claim 14, this supporting
mount is connected to the bearing mount via an air-oil
drive, and the bearing mount can be moved between an
operating position and an inoperative position by the
air-oil drive. In this way, it is possible to switch the
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13~2~
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cylinder quickly by remote control between the lowered
operating position and the raised inoperative position,
also for an emergency stop, whereas the fine adjustment
of the position of the cylinder relative to the web of
mineral fibre in the operating position is made by means
of the adjusting pinion, the position of which does not
need to be changed during breaks in operations or other
interruptions.
Further details, characteristics and advantages of
the invention can be seen from the following description
of a sample version as shown in the drawing.
Fig. 1 shows a side view of one end part of a device in
accordance with the invention,
Fig. 2 shows a transverse view, partially in the form
of a section, of part of the cylinder of a de-
vice in accordance with the invention lying on
the surface of the web o~ mineral fibre, and
Fig. 3 shows a simplified diagrammatic view in perspec-
tive of the cylinder in accordance with Fig. 2.
In Fig. 1, "1" indicates a cylinder as shown in an
enlarged form with details in Fig. 2, and in a simpli-
fied diagrammatic view in perspective in Fig. 3. Fig. 1
simply shows the left-hand end of the cylinder 1 in the
example case; it goes without saying that there is a
corresponding method of mounting the cylinder at the
opposite end. In addition, in Fig. 1, "2" indicates a
shaft which is connected to the cylinder 1, and serves
to bear it. The cylinder 1 is borne by the shaft 2 on a
bearing mount 3 via two-sided bearings 4. Outside the
bearings 4, the shaft 2 enters an electric junction box
5, in which in accordance with the art current is sup-
plied to the rotating parts of the cylinder 1 by means
of slip rings 6, which are shown diagrammatically.
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The cylinder l can be turned in the bearing 4 via
the shaft 2. To provide the rotary drive, an electric
motor 7 is included, which runs on bearings at the bear-
i.ng mount 3, and which has a driving pinion 8 to drive a
driving toothed wheel 9 by means of a toothed belt; the
driving toothed wheel 9 is connected to the shaft 2 in
such a way that it cannot slip. In this way, the cylin-
der 1 can be set in rotary motion in the bearings 4.
The bearing mount 3 can be moved up and down on the
columns 10 of a stationary portal, the whole of which is
numbered ll. Correspondingly, there is a supporting
mount 12 with a tie-bar 13, which can be moved up and
down on the columns 10. The bearing mount 3 is joined to
the supporting mount 12 by means of air-oil drives 14,
for example in the form of pneumatic cylinders 15, which
are borne on the tie-bar 13, and whose piston rods 16
engage with the bearing mount 3 at 17. When the support-
ing mount 12 is fixed, this means that if the piston
rods 16 are withdrawn into the air-oil cylinder 15, the
bearing mount 3 is raised together with the cylinder l,
so that the bearing mount 3 comes to rest in a raised
inoperative position, whereas the lowered position of
the bearing mount 3 as shown in the diagram is the ope-
rating position, which is illustrated in more detail in
Fig. 2.
The supporting mount 12 is in turn connected to a
tie-bar 19 of the fixed portal 11 via adjusting pinions
18. The adjusting pinions 18, for example in the form of
threaded spindles 20 are operated by an electric motor
21, for example in the form of a step-by-step motor and
gearing 22. Using the adjusting spindles 18, the height
of the tie-bar 13 and the supporting mount 12 can be fi-
nally adjusted in the desired position. When the piston
rod 16 of the air-oil drives 14 is extended, this re-
sults in fixing the corresponding height of the cylinder
1. By operating the air-oil drives 14, the cylinder 1
can be lowered to this predetermined operating position
or raised to an inoperative position without changing
the position of the supporting mount 12, which would
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mean that the pre-set fine adjustment would be cancel-
led.
Fig. 2 shows a transverse view of the lower part of
the cylinder 1, partially in the form of a section, in
the operating position. As is clear from the diagram,
the cylinder 1 has a support frame 23 in the form of a
polygon, which in the example case is in the form of an
icosagon, with mounts 25 for heating elements 26 fixed
with screws 27 to its flat lateral surfaces 24. The
heating elements 26 have a mounting frame 28 arranged
inside the mounts 25 and marking ribs 30 protruding from
the surface of the circumference (numbered 29) of the
cylinder 1. The heating elements 26 consist of a suit-
able metal with good heat-conducting properties, and in
the region of their mounting frame 28 they have a recess
31, which is round in the example case, to receive ordi-
nary tubular heating elements 32 - similar to the heat-
ing coils of immersion heaters. To install the tubular
heating elements 32, the heating elements 26 are de-
signed with a split in a plane 33 radial to the axis of
the cylinder 1, in such a way that the parts 26a and 26b
of the heating elements 26 which are formed in this way
are connected with one another by means of suitable
countersunk screws 34 and 35. After the tubular heating
elements 32 have been installed in the recess 31 of the
two open parts 26a and 26b of the heating elements 26,
the heating elements 26 are first assembled by inserting
the screws 34 and 35, and are then inserted in the
mounts 25. Then the mounts 25 are fitted with covering
plates 36 on their outer side, i.e. on the circumference
side; the covering plates 36 overlap the shoulders 37 of
the mounting frame 28 of each heating element 26, and
thus keep it firmly in the mount 25.
The mounts 25 and the covering plates 36 consist of
a suitable material with bad heat-conducting properties,
such as a fibrous or fibre-containing compressed materi-
al on the basis of asbestos or asbestos substitute, in
order to prevent a loss of heat from the heating ele-
ments 26, and to protect the areas of the circumference
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surface 29 on both sides of the marking ribs 30 against
heating up and transferring heat to the mineral fibre
material of the web of mineral fibre, which is numbered
38. In this way, all the sides of the heating elements
26 lying within the circumference surface ~9 of the
cylinder 1 are surrounded by heat-insulating material.
Each heating element 26 has a recess 39 to receive
an earthing cable. At least one of the heating elements
26 also has a recess 40 in the region of its marking rib
30 to receive a thermo-probe. Controlling the tempera-
ture by means of the thermo-probe and supplying current
to the tubular heating elements 32 is done via the slip
rings 6 (cf. Fig. 1). Because the ideal formation of the
markings can be finely adjusted by varying the pressure
of the cylinder 1 on the web of mineral fibre 38, a tem-
perature control using thermo-probes can also be dis-
pensed with, however, and instead, only the current fed
to the tubular heating elements 32 needs to be control-
led. In stationary operation, a certain temperature re-
sults which is suitable for producing the markings, and
the ideal formation of the markings can be adjusted by
the degree to which the cylinder 1 is impressed into the
web of mineral fibre 38.
As can be seen from Fig. 3, the marking ribs 30 of
the heating elements 26 and, if appropriate, the heating
elements themselves only extend over part of the axial
length of the cylinder 1, so that several marking ribs
30 form a broken line along a surface line of the cylin-
der 1, and are arranged at an axial distance from one
another. If the length of the heating elements 26 on the
axial extension of the marking ribs 30 is limited, the
result is a number of individual, shorter heating ele-
ments with thermal expansions that are easy to control.
The heating elements 26 can then be connected to
one another by leads or by a part of the tubular heating
element 32, which needs to be insulated accordingly on
the circumference side, and which connects the heating
elements 26 more or less in the form of an arc. If on
the other hand the heating elements 26 extend over the
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entire axial length of the cylinder 1, and if the gaps
necessary to break the marking are only present between
the protruding sections of the heating elements 26,
which are referred to as marking ribs 30, then a very
robust and stable construction is the result, in which
the tubular heating elements 32 are embedded in the
heating elements 26 over their entire length.
It is preferable for the web of mineral fibre 38 to
be of such a type as is explained in the framework of
the German patent application giving rise to a right of
priority, No. P 36 12 858.9-25. In the example case, let
it thus be an unlined web of mineral fibre 38, 1,200 mm
in width, and 6 m in length. Let the bulk density be
between 10 and 30 kg/m3, in particular between 14 and 25
kg/m3 and in the concrete exampl~ case 18 kg/m3. As a
binding agent, phenolic resin in particular can be used
in a proportion of 6 to 7 % in weight of the dry binding
agent in the product, and in the example case let the
binding agent content of phenolic resin be 6.6 % in
weight (dry). With regard to the properties and the
application of such a web of mineral fibre 38, and with
regard to other details, reference may be made to the
full content of the patent application giving rise to a
right of priority, No. P 36 12 858.9-25.
In operation, when the piston rods 16 are retract-
ed, the cylinder 1 is caused to rotate above the surface
(numbered 41) of the web of mineral fibre 38 by the
electric motor 7; in the process, the heating elements
26 are preheated to a desired temperature by feeding
current to the tubular heating elements 32; if neces-
sary, the temperature can be monitored by thermo-probes.
The rotation during the preheating phase ensures an even
loss of heat by the~ individual heating elements 26 and
marking ribs 30, and thus that they are heated up evenly
without the need for an individual temperature control
on each individual heating element 26. At the beginning
of the production processl the piston rods 16 are ex-
tended, and the cylinder 1 is lowered on to the surface
41 of the web of mineral fibre 38; in the process, the
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electric motor 21 and the adjusting pinions 18 can beused to achieve a fine adjustment of the height of the
cylinder 1 over the web of mineral fibre 38. It is prac-
tical to choose such an adjustment here that the marking
ribs 30 around the circumference of the cylinder 1 press
into the surface 41 of the web of mineral fibre 38, thus
forming a depression 42. The deeper the depression 42 is
pressed into a given web of mineral fibre 38, the great-
er is the contact pressure and the duration of the ef-
fect to improve the conductive heat transfer from the
marking rib 30 to the mineral fibre material. It is typ-
ical for the surface 41 of the web of mineral fibre 38
to be uncovered, which means that it is formed by the
position of the tangle of mineral fibres themselves;
however, the surface 41 can also be lined, for example
in the form of a non-woven fabric on the basis of mine-
ral fibres, or consisting of other fibres.
It is typical for the marking rib 30 to have a tem-
perature in the range of 400C; it produces a region
indicated by the dotted line at 4i in which the binding
agent disintegrates in the web of mineral fibre 38,
which is scorched. In this way, corresponding to the
pattern of the marking ribs 30 visible from Fig. 3.
Marking lines are formed on the surface 41 of the web of
mineral fibre 38, which extend at right angles to the
side edges of the web of mineral fibre 38. By fine ad-
justments using the adjusting pinion 18, the heat trans-
fer conditions can be controlled in such a way that a
marking with sharp edges is produced which is clearly
delimited optically, without there being any impairment
of the material of the web of mineral fibre 38 going
beyond a shallow region of disintegration 43.
Via the driving pinion 8 and the driving toothed
wheel 9, the cylinder 1 can be permanently driven syn-
chronously with the transport speed of the web of mine-
ral fibre 38. It is then practical to use a d.c. motor
as the electric motor 7. In the version illustrated,
however, a three-phase current motor is used as the
electric motor 7, which is connected to the driving
13~ 5
pinion 8 via a free-wheeling system 44 in such a way
that when the cylinder l is driven by the web of mineral
fibre 38, the speed of rotation of the cylinder 1 can
overtake that of the electric motor 7. In this case, the
electric motor 7 drive is used exclusively to maintain a
minimum speed of rotation, which is uncritical from the
point of view of the number of revolutions, when the
drive from the web of mineral fibre 38 is lost in the
raised inoperative position, in order to ensure that the
heating elements 26 heat up evenly.
By operating the adjusting pinion 18, the heat
transfer conditions between the marking ribs 30 and the
surface 41 of the web of mineral fibre 38 can be adjust-
ed in the manner described to form optimum marking
lines. At a predetermined transport speed and consisten-
cy of the web of mineral fibre 38, it is, however, also
possible to dispense with such a fine adjustment,
because it is then possible to work with a fixed pre-
setting of the degree of impression of the cylinder l
into the surface 41 of the web of mineral fibre 38. In
this way, the construction to support the cylinder 1 can
be considerably simplified. If moreover the weight of
the cylinder l can be kept at such a level that the
desired depth of penetration results simply from the
weight of the cylinder 1 imposed on the surface 41 of
the web of mineral fibre 38, then the air-oil drives 14
can be switched to no pressure in the operating posi-
tion, so that the cylinder 1 rests on the web of mineral
fibre 38 simply with its own weight. In this case, too
deep a penetration can be avoided by having the marking
ribs 3~ not protruding by several millimetres (about 8
mm in the example case) from the regular surface 29 of
the circumference of the cylinder 1, but lie within the
regular circumference surface 29, so that the latter -
for example in the form of the covering plates 36 -
helps to bear the weight, which thus prevents too great
a local penetration. The version illustrated, with the
.
f~
13t?21~S
- 17 -
marking ribs 30 protruding from the surface 29 of the
circumference, is, however, particularly well suited to
having the cylinder 1 driven by the web of mineral fibre
38.
