DE3044872A1 - Thermally insulated tubing - two concentric tubes separated by honeycomb system extrusions with intersecting points touching alternate tubes - Google Patents

Abstract

Thermally insulated tubing consists of an inner metal tube, preferably seamless drawn copper, an outer sleeve, and intermediate insulation spacers made up of a number of thermoplastic extruded sections which are bonded together at points to form a honeycomb structure. The insulation spacers have projecting nodes is greater than the gap between inner and outer tubes. The extrusions can be e.g. foamed polythene, polypropylene etc., and the honeycomb can be filled with e.g. foamed polyurethane granules. Highly efficient thermal insulation through the extended heat flow paths, flexible product.

Description

Thermally insulated conduit

The invention relates to a thermally insulated conduit pipe, consisting from a metallic inner tube, preferably a seamlessly drawn copper tube, an outer jacket and one located between the metal pipe and the outer jacket spacing thermal insulation layer in which the thermal insulation layer consists of consists of a large number of adjacent extruded plastic strands, which are connected to each other at alternating points and are thus shaped like a honeycomb Form cavities.

Such a heat-insulated pipe is from DE-OS 23 36 313 known. The plastic strands have a great height relative to their thickness on, which is decisive for the distance between the outer jacket and the inner pipe.

The disadvantage of this construction is to be seen in the fact that a direct Heat flow on the shortest path from the inner tube to the outer jacket is possible.

The invention is based on the object of the heat-insulated conduit pipe of the type mentioned to improve that the thermal resistance of the Isolation layer is enlarged.

This object is achieved in that, according to the invention, the spacer both on the inner tube and on the outer jacket # with hump-like projections is applied point by point and the shortest distance between these two hunting points is greater is the clear distance between the inner tube and the outer jacket. By extending it the path that the heat has to cover from the inner tube to the outer jacket is the The thermal insulation value of the spacer is significantly increased. The length of the heat path, i.e. roughly the shortest connection between a contact point on the inner tube and a contact point on the outer jacket can be approximated according to the theorem of Pythagoras. This is in the event that - as it is after another The idea of the invention is provided - the contact points in the area of the connection points are located, can be seen directly from the figures.

The heat path is, for example, more than three times as long as the shortest Distance between inner tube and outer jacket.

This corresponds - with regard to the body conduction - to the insulating effect a height of the spacer that is more than three times greater than the actual height, with considerable savings in space and material. The honeycomb structure as a strength system is particularly suitable for absorbing the bending transverse loads that occur. For special purposes, you can also run parallel through the connection points arranged longitudinal strands increase the load-bearing capacity or the span, without impairing the insulating effect.

The contact points are advantageously formed in that the height of the plastic strands in the area of the connection points has a maximum. This embodiment of the invention can be produced in a particularly simple manner.

In the case of a thermally insulated conduit, in which the connection points in are located in a cross-sectional plane perpendicular to the longitudinal axis of the pipe, the connection points of every second level have a small contact surface the inner tube, whereas the connection points of the cross-sectional planes in between rest on the outer jacket. This embodiment can with the known device according to the DE-OS 23 36 313 can be easily produced without additional effort. Even better thermal insulation values can be achieved if - as provided according to a further concept of the invention is - the plastic strips made of a foamed thermoplastic material, such as polyethylene, polypropylene or others.

Furthermore, it is useful to have the honeycomb-shaped cavities pourable insulating bodies, such as foam granules, preferably made of polyurethane, to be filled out. As a result, the convection within the through the honeycomb walls, the Outer jacket and the inner tube formed cavities are suppressed and thereby the insulation resistance elevated.

The invention further relates to a method for producing a heat-insulated conduit, in which the spacers by extrusion of a Large number of plastic strands and welding of the plastic strands by means of gas, Steam or liquid jets at changing points directly onto the continuously be applied through the spray head inner tube and on the spacer the outer jacket is applied. The method according to the invention is characterized by this from that the distribution of direction and strength of the gas, vapor or liquid jets is continuously changed over the strand heights, so that at adjacent connection points alternately pointing hump-like projections on the inner tube and the outer jacket form.

The thermally insulated conduit according to the teaching of the invention is good bendable and can be in the form of rings with a Radius of curvature wind up from approx. 1 m. The heat transfer coefficient is well below 0.1 W / m.K ..

Almost all extrudable ones are suitable as material for the plastic strands Plastics. However, it has proven advantageous to use such plastics that can be chemically crosslinked. Networking increases the stability, especially in the heat, the spacer increased significantly. The networking can be achieved by adding a chemical crosslinking agent, e.g. peroxide, to mix plastics. The one necessary for the decomposition of the crosslinking agents high temperature is applied in the spray head itself by shear forces caused by Narrowing and lengthening of the outlet nozzles of the mouthpiece can be enlarged. The crosslinking of the plastic of the spacer can, however, be significant Achieve cheaper if the plastic mixture silanes are added, which after cause crosslinking of the extrusion by supplying moisture.

As a pressure medium for the strand deflection and wear, here expanding steam can be used.

Because of the small cross-sections of the plastic strands and the resulting Achieved large surface area of the spacer, this method can be quickly and perform inexpensively, especially if the plastic strands are made of foamed Plastic are made. An increase in fire resistance results from Use of mineral-ceramic materials for the strands and / or insulating bodies (Perlite balls, glass fiber reinforced fabrics).

The invention is shown schematically on the basis of FIGS. 1 to 8 Embodiments explained in more detail.

It shows: FIG. 1 a perspective view of the conduit pipe, the outer jacket being partially removed. FIG. 2 shows a longitudinal section along the line II-II of Figure 3 through the pipe, with an additional heat-reflecting intermediate film Figure 3 shows a cross section along line I-I of Figure 2 through the pipe Figure 4 a Longitudinal section on an enlarged scale along line IV-IV of Figure 5; through tube and Manufacturing device, in the basic structure according to Figure 1 of DE-OS 23 36 313, with the representation of a welding phase Figure 5 shows a cross section along line III-III of Figure 4, corresponding to Figure 3 of DE-OS 23 36 313 Figure 6 is a longitudinal section according to line VI-VI of Figure 7 with the representation of a honeycomb length by half offset welding phase Figure 7 shows a cross section along line V-V of Figure 6 Figure 8 shows an example of an entire production system for the conduit pipe according to the invention Procedure.

Figure 1 shows a seamlessly drawn copper tube 1, which from an outer jacket 2 is concentrically surrounded.

A spacer is located between the copper pipe 1 and the outer jacket 2 3 arranged, which consists essentially of plastic strands, which at predetermined Places are welded together and a honeycomb structure - as shown - form. Around the contact surface of the spacer 3 both on that The plastic strands are to keep the copper pipe 1 and on the outer jacket 2 as small as possible deformed in the area of the connection points in such a way that projections 4 and 5 which point either to the copper pipe 1 or to the outer jacket 2.

In each case, adjacent projections 4 and 5 should be in the opposite one Show direction. The configuration according to the invention increases the path which the heat from the copper pipe 1 to the outer jacket 2 must cover.

FIG. 2 shows this effect in a particularly clear manner. the released from the heated medium flowing in the inner tube 1 to the copper tube 1 Heat flows via the projection 4 into the web area 6 and from there via the projection 5 in the outer jacket 2. Due to the point-like contact of the projections 4 and 5 the heat transfer is made even more difficult by the copper pipe 1 or the outer jacket 2. Of the Outer jacket 2 consists for example of an aluminum foil or one with aluminum laminated plastic film 7 and / or a preferably extruded plastic jacket 8. The aluminum foil 7 and the plastic jacket 8 should expediently with one another be glued to prevent the aluminum foil when bending the conduit or the laminated plastic film wrinkles or tears. By even fewer support points To obtain, the projections 4 and 5 can be omitted in some connection points. As a variant in the case of the outer jacket 2, the projections may also be permanently welded 5 with the extruded plastic jacket 8 without aluminum foil 7 similar to Figure 1, expedient.

The spacer 3 is placed on the copper tube 1 according to FIGS. 4 and 5 applied by means of a blow molding head, from its circular mouthpiece 9 a multitude of plastic strands emerge parallel to one another, which alternate Way to be welded to the respective adjacent plastic strands.

For this purpose, tubes 10a and 10b are used, each of which is alternately pressurized with air Blow group a and b belong and openings for the plastic strands are made. At the side near the pipe ends there are nozzle openings for the release of pressure media, for example compressed air jets arranged. By going back and forth the tubes 10a and 10b in the direction of the centrally running copper pipe 1 and respective opening and masking the nozzle openings, the plastic strands are mutually transverse deflected towards the exit direction and welded together. Similar blow molding heads for so-called extrusion blow welding with a constant strand height are off the DE-OS 23 36 313 known. It is essential for the invention that the hump-like Projections 4 and 5 through different, constantly changing pressure distribution over can form the height of the strands. The different ones meet this requirement Nozzle bores Ila and 12a in the pipes 10a of the blowing group a (Figures 4 and 5) as well as the nozzle bores 11b and 12b in the pipes 10b of the blowing group b (Figures 6 and 7).

The nozzle bores 11a and 11b are directed as a result of their enlarged Cross-section compared to the cross-section of the nozzle bores 12a and 12b a reinforced Air flow against the corresponding flank sides of the extruded plastic strands, whereby these are deformed so that either the hump-like projections Form 4 (blowing group a) or 5 (blowing group b). As FIGS. 5 and 7 show, is this is connected with a decrease in cross-section of the plastic strands, which is positive affects the thermal resistance.

The nozzle openings for the pressure medium can instead of the unequal Bores 11a to 12b also have other shapes, such as keyhole-like shapes. Also a blow molding head for applying pressure medium without moving Parts can be executed, for example according to DE-PS 1 779 330, or with corresponding Beam deflection means. One possible variant of the pressure medium would be to use it a very high-quality, heat-resistant insulating material instead of or in combination with compressed air. This would stick to the projections and cover them.

Figure 8 shows how a method for producing the complete thermally insulated pipe could expire according to the teaching of the invention. A Copper pipe 1 is inserted into the blow molding head 13, which is on the copper pipe 1 applies the spacer 3. With 14 means are shown which the extruded Spacer 3 should cool down. The one with the spacer. 3 provided copper pipe 1 is continuously passed through a filling device 15, the honeycomb-like Cavities between the plastic strips with prefabricated pourable insulating bodies 17, such as foam granules, preferably based on polyurethane or polyisocyanurate foam, fills out.

A storage funnel 16 is used for this purpose, in which the granulate or the Powder 17 loosened or loosened by a screw 18.

is also driven forward. A connecting piece 19 serves the same purpose a compressed gas can be introduced into the funnel 16, which the conveying of the powder or granulate 17 facilitates or compacts it.

One in communication with the storage hopper 16 via a pipe elbow standing hopper 20 with guide tubes 21 and 22 presses the granulate or Powder 17 into the honeycomb cells acting as a displacement conveyor system. The setting a small hopper angle results in higher compression; becomes the angle enlarged, the result is a looser filling with better insulation values.

After the guide tube 21, the honeycomb tube is from an aluminum foil 7 running longitudinally over a molding channel 23 or one with aluminum coated with vapor-coated plastic film and its longitudinal overlap, as shown at 21., welded or glued. By means of an extruder 25, the outermost Protective layer 8 of the outer jacket 2 are extruded on.

Compared to a conventional line pipe manufacturing line with full foam insulation, the length of the new system is considerably shorter because the complex curing section for the solid foam, the double devices for foam casting, prefabrication and spinning of the spacer helix and others Devices are not required. As a pourable insulating body can also. Foam scraps, the elimination of which has so far meant a significant environmental impact, fully reuse.

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Claims (8)

Claims heat-insulated conduit, consisting of a metallic conduit pipe, preferably a seamlessly drawn copper pipe, a Outer jacket and a spacer located between the metal tube and the outer jacket Thermal insulation layer in which the thermal insulation layer consists of a variety of adjacent extruded plastic strands, which are alternating Places are connected to each other and thus form honeycomb-shaped cavities, characterized. that the spacer (3) both on the inner tube (1) as also rests pointwise on the all-round jacket (2,7) with hump-like projections (4,5) and the shortest distance between these two contact points is greater than the clear one Distance between inner tube (1) and outer jacket (2.7). 2. Heat-insulated pipe according to claim 1, characterized in that that the contact points are located in the area of the connection points. 3. Heat-insulated pipe according to claim 1 or 2, characterized in that that the height of the plastic strands in the area of the connection points is a maximum having. 4. Heat-insulated conduit according to claim 1 or one of the following, in which the connection points are perpendicular to the longitudinal axis of the pipe Cross-sectional planes are located, characterized in that the connection points every second cross-sectional plane with a small contact surface on the inner tube (1) rest, whereas the connection points of the cross-sectional planes in between rest on the outer jacket (2,7). 5. Heat-insulated conduit according to claim 1 or one of the following, characterized in that the plastic strands are made of a foamed, in particular thermoplastic material such as polyethylene, crosslinked by means of silane or peroxide, Polypropylene etc. are made. 6. Heat-insulated conduit pipe according to claim 1 or one of the following, characterized in that the honeycomb-shaped cavities with pourable insulating bodies such as foam granules, preferably made of polyurethane, are filled. 7. Process for the production of a thermally insulated conduit pipe according to claim 1 or one of the following, wherein the spacers by extrusion a variety of plastic strands and welding the plastic strands by means of Gas, steam or liquid jets at changing points directly onto the continuously be applied through the spray head guided metal pipe and on the Spacer of the outer jacket is applied, characterized in that the Distribution of direction and strength the gas, vapor or liquid jets is continuously changed over the strand heights, so that at adjacent connection points Alternating hump-like projections pointing towards the inner tube and the outer casing form. 8. The method according to claim 7, characterized. that before Applying the outer jacket, the honeycomb-like cavities with pourable insulating bodies, preferably foam granules or powder are filled.