Note: Descriptions are shown in the official language in which they were submitted.
86~38
The subject of the invention relates to a method for
- the continuous manufacture of a tube or tube bundle provided
with an insulating covering made of preferably closed-cell
thermoplastic foam plastic, the insulating covering being
obtained from a flat strip of foam plastic by deforming it
transversely to its longitudinal extent and closing the butt
joint by welding or luting.
Insulating coverings made of foam, thin-walled or
thick-walled, with smaller or larger diameters, are used
particularly for the purposes of insulation against cold or heat,
e.g. for the whole sanitary installation such as hot water, cold
water, waste water, heating lines, cold lines etc. Insulating ~ `
coverings of this type may either by directly extruded from
foam. However, it is also possible to manufacture them from
foam strips. The latter method is particularly for foams which
cannot be extruded directly, such as cross-linked polyethylene
foams. The foam strip is here manufactured as continuous process
goods either by extrusion with after-foams or on the spread coating
technique, the latter method being used eOg. with soft PvC foam.
Manufacturing insulating coverings from strips of deformable
; thermoplastic foams is known from German Patent Specification
`; l9 15 768 by bending the foam strips and folding them together
flat, the butt joint being welded or luted.
An insulating covering made of a closed-cell foamed
' plastic for tube insulation is also known from German Utility
i. Model 75 09 227 which is slotted in longitudinal direction and
in which this slot is closable by a sliding fastener welded on.
These known insulating coverings are then pushed on
to the tubes for insulation later and the longitudinal slot is
then closed for instance by welding, luting or by means of the
sliding fastener mentioned above. The object now underlying
the invention is to simplify this manufacture of the insulated
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tube and to design the whole operation 50 as to make it easier
to assemble for installation.
According to the present invention there is provided
a method for the continuous manufacture of a tube or tube
bundle provided with-an insulating cove-ring made of closed-
cell thermoplastic foam plastic, the insulating covering being
obtained from a flat strip of foam plastic by deforming it
transversely to its longitudinal extent and closing the butt
joint by welding or luting, characterised in that the foam
plastic strip is briefly heated on its side which will later
- form the inside of the insulating covering until it reaches
the thermoelastic or thermoplastic state and is then preformed
into the insulatlng covering cross-section, this insulating
covering-preformed piece is then cooled down slightly if
necessary and the tube or tubes are continuously inserted
through the open butt joint of the insulating covering-preformed
piece and the butt joint of the insulating covering is then
closed.
The brief heating, mentioned above, of the later
` 20 lnsulating covering interior side up to the thermoelastic or
~hermoplastic state produces an increase in flexibility, with
the result that also small tubes or small tube bundles can be
provided with a relatively thick insulating covering. At the
same time, however, the result of this heating is a drop in
; ~he tensile strength of the foam strip, with the result that
`` when ~he insulating covering is de~ormed, undesired longitudinal
and transverse deformations would occur due to unavoidable
Erictions with apparatus parts. According to a Eurther
embodiment, this is prevented by a rotating conveyor belt
with a rough surface, which provides for the further transport
of the strip particularly when it is in the heated state.
Thus, pre-stretching of the insulating covering is avoided.
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The tube or tube bundle and insulating covering are of
virtually the same length. When an insulated tube bundle is
later separated, any shrinking back of the insulating covering
relative to the inner tube or inner tubes is prevented.
According to the invention, the manufacture of the
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insulating covering from a flat foam plas-tic strip is thus
combined with the continuous insertion of the tubes to be
- insulated and the subsequent closing of the butt joint of the
insulating covering. In the method suggested according to the
invention, the insulated tubes may then be cut to length as
required direct from a supply roll or be cut to length for stock-
piling. It is possible to enclose not only one tube with an
insulating covering but to surround two or even more tubes,
combined into a tube bundle, wi-th one single insulating covering
at the same time. It is also possible, with the method according
to the invention, to provide more than one insulating covering
since the insulated tube or tube bundle can be enclosed once
more with a further insulating covering. The advantage over
-the known methods in which the tubes to be insulated have either
; to be inser-ted by sections into already closed insulating
coverings in longitudinal direction or in which, in,the case
of slotted insulating coverings, this slot has to be closed in
each case for the individual insulated tube, is obvious.
Since in the suggested method according to the
invention no fixed connection between the insulating covering
and the tubes located in the interior is produced, the advantage
emerges in assembly, namely that the insulating covering can be
pushed back at each of the coupling ends and therefore during
assembly the tube ends are free, but when assembly is completed,
-the coupling point is again covered by the insulating covering
and is thus automatically insulated.
After closing the butt joint of the insulating covering,
round the tubes, it is also possible briefly to subject the
insulated tube or insulated tube bundle once more to a heat .
treatment (tempering) on the outside, possibly with subsequent
cooling, in order to remove residual tensions from the insulat-
ing covering.
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Developing the method of -the invention, it is further
suggested that when there are several tubes to be encased, the
butt joint of the insulating covering is located in the area
between two tubes where there is no contact between the insulating
covering and the tubes. In this way it is possible to have good -
compression of the insulating covering in the area of the butt
joint and thereby a secure closure without the tubes located
inside being damaged, e.g. by a wedge-shaped weld.
The method according to the invention for the continuous
enclosing of tubes while simultaneously manufacturing the insu-
lating covering is applicable both for flexible as well as for
rigid tubes. Plastic tubes of radiation cross-linked poly-
ethylene are particularly suggested as flexible tubes for the
method of the invention. It is also possible, however, to
insulate rigid tubes, e.g. copper tubes, with the method accord-
ing to the invention.
When flexible tubes are used, it is suggested that
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when manufacture for the insulating covering takes place in one
plane, the flexible tubes be guided continously from above at
an acute angle into the insulating covering. It is also possible,
here, to lead several flexible tubes into the insulating covering
, parallel with one another from several supply rolls disposed,
- for example, next to one another or one above the other. If
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~` several tubes are run singly into the insulating covering
~arallel with one another and arranged into a tube bundle, it
is possible to fix them by sections by an adhesive strip, for
cxample, placed round them externally, and to guide them into
- -the insulating covering in this form. By this means, their
position relative to one another within the insulating covering
also is fixed more definitely.
Furthermore, it is an advantage that after the insu-
- lating covering round the tube or tubes has been closed, an
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; external heat treatment is carried out briefly until the
-, plasticizing tempera-ture of the foams is reached. This after-
tempering removes tensions both from the insulating covering and
if necessary from the enclosed tube.
.~ An embodiment of the invention is represented in the
. drawing and is explained in more detail with reference to
this below.
Figure 1 shows a diagramma-tic representation of
~he procedure on an apparatus for manufac-
turing tubes insulated with foam strips,
Figure 2 shows a diagrammatic cross-section through
the apparatus according to section A-A of
Figure 1, :
Figure 3 shows a diagrammatic view of the apparatus
according to section B-B of Figure 1, .
Figure 4 shows a diagrammatic view through the
apparatus according to section C-C of :
Figure 1, and
Figure 5 shows a cross-section through an insulated
tube bundle,
Figure 6 shows a cross-section D-D of Figure 1.
With the apparatus represented in Figure 1, foam
strips 2 made of a thermoplastic and deformable material, wound
on ~o supply rolls 1, are processed into insulating coverings. ~:
~he strip 2 runs fxom the supply roll 1 via the deflection
roll 3 on to the working table 4 on which a welding apparatus 5,
~or oxample, is provided. Thiq apparatus 5 is r~uired for
: continuously joining the ends of the strips 2 together when the
roll is changed. From the working table 4, the strip 2 runs
through the guide roll pair.6 where it runs off on to the
continuous belt 8. The belt 8 assumes the function of carrier
` for the strip 2 and for this purpose the belt 8 has a very rough
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top side, e.g. like an emery strip with optional granulation.
This belt 8 has good mechanical adhesion to the strip 2~ This is
~ important since with the subsequent heat treatment the strip
- loses mechanical rigidity and there would o-therwise be the risk
that it would not be carried along evenly or would be stre-tched.
The continuous belt 8 with the strip 2 is guided through the
various apparatuses and is deflected at the end of the pressing
apparatus 20 and guided back to -the guide rolls 6 via the
- tensioning roll 17. The belt 8 is driven via the drive roll 22.
Since the strip rests on the belt 8 and is transported,
- the strip runs through the heating apparatus 7, see also the
diagrammatic cross-section according to Figure 2. The heating
- apparatus may be operated with air, radiators etc. On passing
through, the strip is heated on one side, i.e. on what will
later be its inside, and is transformed into the thermoplastic
sta-te, the heating advancing only so far over the tpickness of
the strip's cross-section that the reverse side, later the
outside, remains virtually cold and unplasticized and enables
the mechanical transport and adhesion on to the strip 8 to take
place. The heating temperature and heating time depend on the
properties of the foam and the thickness of the strip. Plastifi-
- cation, i.e. heating up to the thermoelastic or transition
into -the thermoplastic state, of up to about half the thickness
of the strip altogether is here desirable, although in no case
may plastification go so far as to destroy the foam structure.
This heat treatment which the strip undergoes when it passes
-through -the heating apparatus 7, is roughly equivalent to
-tempering. The conveyor belt ~ here runs via the working plate
13. The heating area is screened by the lateral screening plate
9 so that even heating of the strip in the marginal areas is also
ensured.
` After leaving the heating apparatus 7, the strip 2,
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partially heated to the plastificatlon state, is conveyed to
the apparatus for reshaping into the insulating covering cross-
: section. The strip 2 here runs into the moulding funnel 10 which
reshapes it to the desired cross-section. Direc-tly connected
to the moulding funnel 10 is the moulding tube 14 whose internal
contour may correspond as far as possible, by being round, oval,
or in some other way, to the desired cross-section of the insu-
lating covering. This cross-section may preferably be adapted
to the shape of the tube or tube bundle. The moulding tube,
however, is constructed with the slot 14(sic) on the top side
; at least in the entry area and also at the exit end, as is also
clear from the diagrammatic cross-section in Figure 3. Into
this guide slot 14a at least in the entry area, engages the
guide rail 12 which simultaneously engages into the butt joint
of the strip moulded into the insulating covering-premoulded piece
2a and marks this so that torsion of the premoulded,piece
during the subsequent further transport is avoided. The moulding
tube 14 is further provided with the cooling apparatus 11,
cooling air, preferably, being blown into the moulding tube 14.
This ensures that the premoulded piece 2a cools down again and
hardens slightly when it passes through the moulding tube 14.
The strip 18 is also guided into the moulding tube 14 and adap-ts
itself to the internal contour of the moulding tube, through
which the premoulded piece 2a exerts a pressure on the transport
belt 8, with the result -that perfect transport takes place
. despite the friction in the moulding tube. The width of the belt
8 may be conside~rably smaller than the width of the strip 2,
for instance a quarter to half of it. Further guide rolls 16
may be disposed at the end of the moulding tube 14 but this is
not absolutely necessary and depends on the insulating covering
to be manufactured. It is an advantage, however, to provide a
`~ guide rail 15 on the top side in the exit area as well, which
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engages into the butt joint 39 of the premoulded piece 2a and
' prevents it from twisting. This 1s also important for the
-~ following reason: so that the butt joint of the premoulded piece
always leaves the moulding tube at the same point and in this
position of the following apparatus for closing, ~he butt moulded
- piece 2a is closed, the tube 38 or tubes 38a, b, c, drawn off
from one or several supply rolls 37 and coming from above,
: approaching at an acute angle, are now inserted through the
open butt joint into the insulating covering-premoulded piece 2a.
The tube 38 or tube bundle 38a, b, c coming from one
or several supplyrolls 37 is expediently conveyed via roll
r~ guides 40 or guides of other design in order to ensure accurate
introduction into the insulating covering-premoulded piece and
accurate approach for the connecting operation described below,
e.g. by welding, the edges of the insulating covering. Struts
(not shown here) in the area of the entry of the tube or tubes
into the insulating covering-premoulded piece similarly contribute
to a disruption-free and accurate working cycle.
The preformed piece 2a which is still open is now
closed, for, example by welding the butt joint, luting the butt
joint, possibly even enclosing with a foil with an adhesive
edge or welding on a sliding fastener etc. In the embodiment
shown, a welding apparatus l9 for welding the butt joint 39 of
the preformed piece 2a is attached as may also be seen from
-the cross-section in Figure 4. To obtain a perfect weld of the
butt joint, the preformed piece 2a is guided with the tubes 38a,
b between an upper and a lower hold-down plate 18a, b which press
the preformed piece into an approximately oval cross-sec-tion, the
long axis being disposed horizontally. The butt joint 39 is on
the top side so that the heating sword 19 engages into the butt
joint and plasticizes the surfaces so that they weldO Further-
more, there are lateral adjustable guide connections 36 provided
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as lateral boundary. In this compressed cross-sec-tional shape
- the insulating covering 2b welded up at the butt joint is insert-
ed directly into the pressure apparatus 20 which over a prescribed
length holds the insulating covering 2b in the prescribed posi-
tion until the welded joint has hardened. At the end of the
pressure apparatus the belt 8 transporting the insulating
covering is drawn off and conveyed back to the exit, whilst
further transport of the insulating covering 2b wi-th the tubes
38a, b to a following heating apparatus 24 takes place by means
of the guide rolls 23.
The pressure apparatus 20 may also be designed to
~ulfil functional tasks in another way. The cross-section of
a pressure apparatus is shown in Figure 6. Shaped rolls 41 and
possibly smooth rolls 42 which can be disposed repeatedly one
behind the other in axial direction, fix and transport the
insulating covering 2a while the butt joint 39 is hardening.
Corresponding to the roll cross-sections, the conveyor belt
8 rests against the insulating covering which in turn partially
bears on the tube 38.
~ pressure apparatus which simultaneously transports
-~he conveyor belt 8, tube or tube bundle 38 or 38a, b , c and
insulating covering 2a while the connection seam is hardening,
may, however, also be designed differently.
The rolls 23 which can be disposed after the pressure
apparatus 20 assume the task of tube guiding. The second
heating apparatus 24 then follows, if necessary, which carries
out the external tempering of the insulating covering 2b. As
it passes through the heating apparatus 24, -the insulating
covering is heated on its outside surface until the outer skin
is plasticized, but only briefly so that the foam structure is
retained. Through this heat treatment the last tensions remain-
ing in the insulating covering in its outer layer are tempered
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ou-t so that there are no tensions remaining which tend to res.et
it into a flat strip. This tempering operation similarly leads
- to the removal of longitudinal tensions and thus similarly
contributes to the tube or tube bundle being the same length
as the insulating covering. When a tube section is later cut
to length, there is then virtually no shrinkage of the insulating
covering relative to the insulated tube or tube bundle. After
~- leaving the heating apparatus the insulating covering with the
tubes is cooled again, it being guided for instance through the
cooling tube 27. The cooling tube 27 may be operated by cooling
air, for instance, conveyed via the entry 26. Disposed in
front of the cooling tube 27, expediently,is a diaphragm 25
which ensures perfect supply of the cooling air. The cooling
-tube 27 may be exchangable and in its interior shape be rnatched
to the particular insulating covering for manufacture. Further
removal takes place via the take-off rolls 29. In the case of
flexible insulated tubes, the insulated tube or tube bundle may
then subsequently be wound on to a supply roll, for instance.
In the case of rigid insulated tubes, cutting to length then
-takes place.
With the method according to the invention, a tension-
free and form-licking tube insulation from foam strips may be
manufactured on the apparatus described.
With the method according to the invention, insulated
tub~s or tube bundles are manufactured in one working cycle,
where, therefore, subsequent assembly or subsequent attachment
oE the insulating covering on to the tubes or tube bundle is
. therefore dispensed with. .
If rigid tubes, e.g. copper tubes, instead of flexible
tubes, are to be insulated, it is then expedient to transport
.-~ these tubes in one plane, whilst the elastic and deformable
~. insulating covering is conveyed at an acute angle to the tube
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which is guided in a straight line. It is also possible,
; following the method according to the invention, -to provide
with an insulating covering tubes coming directly from a manu-
facturing process, e.g. extruded plastic tubes coming from the
extruder.
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