DE202004020674U1 - Metal composite pipe consists of at least one plastic inner pipe and a metallic envelope surrounding it, and a thermo-setting bonding agent that connects them - Google Patents

Abstract

A plastic-metal composite pipe (1) consists of at least one plastic inner pipe (2) and a metallic envelope (3) surrounding it. The inner peripheral surface (6) of the metallic envelope is fixed to the outer surface of the plastic inner pipe, and the envelope consists of a metal strip. Opposing edges of the strip are arranged so the metallic envelope is double layered over the entire periphery. A thermo-setting bonding agent or adhesive is used to join the inner pipe and the metal. The arrangement used to produce the pipe consists of an unwinding unit (11) from which the inner pipe is drawn off, a second unwinding unit for the metal strip, and a forming unit.

Description

The The present invention relates to a plastic-metal composite pipe and a device for its production.

In the production of plastic-metal composite pipes or plastic-metal-plastic composite pipes, it is inter alia necessary to form-fit a plastic inner pipe with a thin metal strip, as exemplified in US Pat 1 is shown. Such composite pipes have been known for a long time. Also, various manufacturing processes in the production of these composite pipes are known (see DE-A-32 25 869, DE-A-43 10 272, DE-A-197 31 580 and EP-A-639 411).

All Previously known methods assume that after creating the metal shell a welding process takes place around the band edges of the metal shell formed into a slot tube with a longitudinal seam or one in the longitudinal direction extending weld to weld and thus close the metal sheath in particular diffusion-tight. Of the Metal jacket serves as a diffusion barrier. The volume of the band Metal sheath is of minor importance in the art and can be adapted to the intended use of the pipes. decisive is that when welding the longitudinal seam no mistakes (holes or slots) arise. Defects in the weld of the Metal mantle can in certain circumstances disable the diffusion barrier.

at Lowering the tape thicknesses for the Metal jacket increases the risk of faulty welding. Out that's why they're getting stronger metal bands as necessary for the purpose of a diffusion barrier necessary to ensure a smooth Production and to make the reject rate bearable hold.

With The present invention is a composite pipe of the aforementioned Kind be provided, which are produced inexpensively and / or flexible or easy to lay. Furthermore, according to the present Invention a method and an apparatus for its production to be provided.

These Task is solved by a composite pipe having the features of claim 1 and by a device according to claim 11 further advantageous embodiments The invention are the subject of the dependent claims.

The pipe according to the invention is provided with an inner tube made of plastic and a sheath from a arranged around the inner tube around metal strip, wherein the metal band over essentially 360 ° double-layered is arranged around the inner tube, and in that the Metal strip laid in its transverse extent around the inner tube or is wound.

Advantageous it is when the circumferentially arranged band edges of the Metal strip of the inner tube offset by at least the thickness of the metal strip to each other and that's in its itself between the band edges extending portion is substantially Z-shaped.

at a plastic-metal composite pipe according to the invention are the opposite ones longitudinal edges of the metal band so on top of each other guided, that the metal tube is substantially over its entire circumference double-layered or as one above the other lying double jacket is formed. Because the inner peripheral surface of the metal tube tightly fitting on the outer peripheral surface of the Plastic inner tube rests, there is no according to the invention Need more, the two long sides of the metal strip to be welded together. Thus, in the invention a weld the metal strip and in particular at the longitudinal edges not given.

By this surprising simple measure eliminates a number of disadvantages or limitations that are conventional Composite pipe with a longitudinally welded metal jacket adhere. According to the invention, a high, punctiform acting Melting temperature of the arc during longitudinal seam welding for the connection the two band edges are bypassed. Local overheating leading to connection errors to lead can, are therefore avoided. In addition, it opens so the way, the contact surfaces of the Double mantle for one to prepare for good connection of the superimposed strip surfaces.

One another big one Advantage is in the size of the surfaces themselves to see that for the connection of the double mantle or the superimposed band surfaces to disposal stands. While in the prior art, the band edges only along a longitudinal seam, i.e. essentially linear, can be connected to each other, consists according to the invention the entire Circumferential surface, i.e. essentially the entire outer peripheral surface of a Inner layer of the double-layered metal tube and essentially the entire inner circumferential surface of a backsheet the double-layered metal sheath, available. This favors both cohesive as well as non-positive Compounds of said surfaces, as below in more detail accomplished becomes.

Another advantage is that during manufacturing no more welding errors are possible must be respected. This finding applies to both the mechanical stress of the metal shell as well as its functions as a diffusion barrier. According to the invention, welding installations and testing equipment for checking weld seams are superfluous. The use of expensive inert gas can be omitted. The production of the tube according to the invention is thus not subject to any speed restrictions, which are caused by a welding process itself.

According to one preferred embodiment the plastic inner tube sheathing metal sheath as a double-layered Metal jacket formed.

Prefers lies the inner peripheral surface of the Metal shell tight on the outer peripheral surface of the Plastic inner tube on. Preferably, the opposite lie surfaces of the double-layered metal shell firmly or close to each other at. This favors both cohesive as well as non-positive connections between the mentioned surfaces. Of the Conclusion or adhesion between said surfaces can also by the different thermal expansion of metal strip and plastic inner tube favors provided at least one of the process steps used for the preparation occurs at a relatively high temperature and as a double-layered metal sheath formed metal strip on cooling shrinks on the plastic inner tube.

Advantageous It is when the band edges of the double-layer metal shell, the is formed around the inner tube, are arranged in the circumferential direction, that the mutually facing band edges of the metal strip around at least the strenght the metal band are offset from each other and that the metal band in its extending between the band edges in the area Essentially z-shaped is shaped.

While it according to the invention in principle is that the double-layered metal shell exclusively on Reason for a frictional connection as a result of the flat contact between the for the Connection available standing surfaces (for example by calibration procedures) takes place, is very particularly preferred in addition a material connection between the for the Connection of available standing surfaces used. Preference is given to the material bond by a thermosetting Adhesive or adhesive accomplished. The activation the adhesion promoter or adhesive temperatures required are much lower than those required for welding Temperatures. This eliminates disadvantages associated with excessive heating attributable to composite materials. It is also advantageous that required for activation of the adhesion promoter or adhesive heat treatment inductively it follows. At least one side of the metal strip is preferred with the thermosetting Adhesive or adhesive to be coated, so that a cohesive connection between the plastic inner tube and the metal shell and / or between the inner layer and the outer layer of the metal shell.

Because the metal strip is formed into the double-layered metal shell is so automatically a large area connecting to disposal provided that ensures a high mechanical stability of the composite pipe.

Appropriately includes The composite pipe will continue to have a plastic outer sheath that is connected to the outer layer the metal shell is material or non-positively connected. The plastic outer jacket is dependent in every case from the basic shape of the inner tube.

Because no welding operation is required for the production of the double-layer metal jacket for composite pipes according to the invention, the wall thickness of the metal shells can be designed much thinner overall than is the case in the prior art. In principle, any wall thicknesses are suitable for the metal double-jacket system according to the invention. However, very thin bands (eg 10 ^-1 mm range, eg 0.1-0.2 mm) are preferred to use very thin bands.

With consideration on the expected increase in production of the sheathing the inner tubes with the inventive double-layer metal jacket System opposite the conventional one Inner tube production, preference is given to the production process of Coil recommended to coil. the reason for this are the relatively high speed differences between the inner tube and sheathing systems. According to the state of the art, it is for Time not possible the production of the inner tubes the expected jacketing speeds adapt. This is a synchronization between inner tube production and Sheathing plant only possible if capacity losses at the jacket can be accepted by the user.

The tube according to the invention can be made by providing the plastic inner tube as an endless tube which is wound on a large coil and withdrawn therefrom at a predetermined speed and an endless metal strip is provided in the form of a coil and withdrawn synchronously with the inner tube, the opposite edges of the metal strip are guided one above the other so that the metal tube is substantially double-layered over its entire circumference or as a superimposed one another Double jacket is formed.

Connection error, because of welding defects, local overheating, excessive mechanical Tensions etc., can According to the invention when closing the Metal double mantle be excluded. Thus, the production is of the tube according to the invention economical and allows a smaller committee.

High precise Tape edge guides which is required in the prior art in longitudinal seam welding are, can omitted according to the invention. According to the present Invention, the metal strip as an endless metal strip or Metallcoil to be bought. The usual Width tolerances of the metal bands according to DIN standard are for the above method is sufficient because the opposing ones Edge of the metal strip must not be in shock, but the metal strip rather double-layered around the plastic inner tube to be reshaped around.

Consequently According to the invention, even elaborate tape preparations are superfluous. Also falls according to the invention no more metal waste, which in the prior art by trimming the metal bands arises. Also winding or crushing machines for the hem strip become superfluous. According to the invention of Metal casing can be absolutely adapted to the purpose of use, without consideration on weldability. This results in a considerable saving of material, which the Costs down further.

Prefers the heating device is a profiling device downstream, to further profile the composite pipe, in particular to limit or suitable to mold, so that the plastic inner tube with the as Double-layered metal casing are firmly enclosed or tightly fitting.

Prefers is the profiling for designed a pipe diameter and the tools are changeable, so that other pipe diameters are possible. The double-layered Metal jacket is molded around the inner tube, heated, calibrated, extruded (Outer coat) and cooled.

following become preferred embodiments of the present invention with reference to the drawings, wherein:

1 in a schematic cross section represents a composite pipe according to the present invention;

2 in a greatly enlarged cross section a section of the composite tube according to the 1 in the region of the opposite edges of the metal strip shows;

3 the composite tube according to the 1 represented in a perspective partial section

4 schematically illustrates an apparatus for producing a composite pipe according to the invention.

In the figures denote identical reference numerals identical or essentially equivalent elements or functional groups. When studying The following description will provide the person skilled in the art with further features, Advantages and modifications according to the present invention Invention will become apparent.

The 1 shows in a schematic cross section the plastic-metal composite pipe according to the invention 1 , To the plastic inner tube 2 around is a thin metal band with a transverse dimension, which is approximately equal to twice the outer circumference of the inner tube 2 is to a double-layered metal coat 3 shaped. The metal coat 3 has an outer layer 5 and an inner layer 6 on. To the outer layer 5 around is an outer coat 4 , suitably made of plastic.

The inner layer 6 is firmly or snugly against the outer peripheral surface of the plastic inner tube 2 on. The outer layer 5 lies firmly or close to the inner layer 6 on. Appropriately, the outer jacket is located 4 tightly fitting on the outer peripheral surface of the outer layer 5 on.

Like in the 1 shown, the two edges or longitudinal sides of the metal strip are guided one above the other, that the metal tube or metal sheath 3 is formed over its entire circumference double-layered or as a superimposed double jacket substantially.

For forming the metal strip around the inner tube 2 the metal strip is initially formed overlapping with its band (longitudinal) edges to form a tubular body whose diameter is substantially larger than the outer diameter of the inner tube 2 is.

During further forming, the resulting tube body diameter is formed ever narrower, until the inner diameter of the metal shell fixed or tight-fitting on the outer diameter of the plastic inner tube 2 rests. Thus, the metal sheath is doubled over the entire circumference.

For the production of the doubled metal sheath, an extremely thin metal strip can be used, which can also be surface-treated (coated). The wall thickness of the metal bands used is half of the given Standards limited and corresponds by the duplication again the standard.

The 2 shows in a greatly enlarged cross section the area of the opposite edges of the metal strip. Like in the 2 shown, the edges of the metal strip are circumferentially spaced from each other at a distance corresponding to at least one wall thickness of the metal strip.

Overall, the inner layer 6 of the double mantle 3 in the region of the edges of the metal strip thus z-shaped and tight fitting in the outer layer 5 of the slot pipe 3 transferred. In the transition area 7 so no disturbing burrs or protrusions, which could easily lead to mechanical damage. The outer peripheral surface of the metal tube or metal sheath 3 thus runs in the transition area 7 essentially steady.

The 3 shows in a partial perspective section of the composite tube according to the 1 and 2 , On the outer circumference of the plastic inner tube 2 and / or the inner circumference of the inner layer 6 of the slot pipe 3 is a bonding agent or adhesive, which is preferably thermosetting, applied. On the outer circumference of the outer layer 5 of the metal mantle 3 and / or the inner periphery of the outer shell 4 is a bonding agent or adhesive, which is preferably thermosetting, applied. The heat curing of the adhesion promoter or adhesive can be activated at substantially lower temperatures than those occurring in the prior art during welding. For the cohesive connection, the aforementioned surfaces are available over the entire surface, which additionally increases the stability of the composite pipe.

The 4 shows in a schematic cross section an apparatus for producing the composite pipe according to the invention. During production, the composite pipe to be produced passes through the device 10 from right to left. The plastic inner tube 2 is as an endless tube on the first coil unwinder 11 wound. Alternatively, the plastic inner tube 2 also be extruded continuously during manufacture. It is expedient then an unillustrated buffer for the plastic inner tube 2 and / or the metal band 20 provided to buffer delays during manufacture.

The metal band 20 is in the form of a coil of an unwinding device 12 provided.

The plastic inner tube 2 and the metal band 20 are peeled off at the same speed, leaving the metal band 20 synchronous with the plastic inner tube 2 starts to rotate. Before the metal band 20 is molded on at least one surface of a coating apparatus 13 coated with a preferred thermosetting adhesive or adhesive.

Then run the plastic inner tube 2 and the metal band 20 in a molding line or forming device 14 for the metal band 20 one. In the shape range 14 becomes the metal band 20 to that in the 1 illustrated double-layered metal jacket 3 deformed so that this is substantially coaxial with the plastic inner tube 2 starts to rotate. Already at the exit of the shape course 14 includes the two-ply metal shell 3 the plastic inner tube 2 tight fitting or non-positive.

Subsequently, the inner tube passes through the double jacket an inductive heating device 15 , which selectively the metal tube 3 heated. The heating power of the inductive heating device is designed so that the thermosetting adhesive or adhesive for cohesive connection between the plastic inner tube 2 and the double-layered metal jacket 3 and / or between the inner layer 6 and the outer layer 5 of the double-layered slot tube 3 is activated. It is thus a heating of the metal of the double mantle 3 above a predetermined minimum temperature required. The heating power depends, for example, on the material thickness, on the materials and on the throughput speed.

Subsequently, the heated structure passes through a calibration device 16 where the profile of the produced composite pipe I is dimensionally calibrated and glued, wherein the plastic inner tube 2 and the double-layered metal coat 3 rest firmly or tightly. The calibration device 16 is determining for the outer diameter of the metal shell.

Subsequently, the jacketed inner tube passes through an extruder 17 that has a plastic outer jacket 4 extruded. Subsequently, the structure passes through a cooling device 18 For example, a water bath. The resulting composite pipe is wound up as an endless tube. For the plastic inner tube 2 a variety of plastics can be used, for example polyamides, polyethylenes, PVC. Polyacetates, fluoroplastics. Most preferably, highly crosslinked polyethylenes (PE) or PVC are used. To activate the thermosetting adhesion promoter or adhesive, temperatures up to about 150 degrees Celsius may be sufficient. Instead of the bonding agent or adhesive in the coating device 13 to apply, according to the present invention, the metal strip 20 Of course, also be purchased in a coated state. Adhesion agents can also be dispensed with altogether.

In all the aforementioned embodiments, the material of the metal strip is subject 20 basically no restrictions. The metal band is expedient 20 made of aluminum, copper, steel, stainless steel.

The Manufacturing process for the composite pipe according to the invention is characterized in particular by the following further advantages from: expensive tape preparations (banding, straightening, etc.) can be omitted. By eliminating complicated welding systems and seam inspection systems and seam guiding systems can process monitoring be greatly simplified. In particular, they are not expensive Welding testers required. For the Process flow is no protective gas required. A procedural Production of scrap metal can be omitted, as no band trimming equipment is required.

According to the invention that Composite pipe thus without consideration on the weldability be formed of the metal shell. It can thus we considerably higher Achieve production speeds. With the above-described Technology can thus save strip material, increase productivity and monitoring the manufacturing facility are facilitated.

Claims (15)

Plastic-metal composite pipe with a plastic inner pipe ( 2 ) and a metal tube with a metal jacket ( 3 ), wherein the inner peripheral surface ( 6 ) of the metal shell ( 3 ) tightly on the outer peripheral surface of the plastic inner tube ( 2 ) and the metal shell ( 3 ) is formed from a metal strip with opposite longitudinal edges, characterized in that the opposite longitudinal edges of the metal strip are guided one above the other so that the metal shell ( 3 ) substantially over its entire circumference double-layered or as superimposed double jacket on the plastic inner tube ( 2 ) is shaped. A composite pipe according to claim 1, wherein the longitudinal edges are not welded together, but the metal pipe as a double-layer metal shell ( 3 ) is trained. A composite pipe according to claim 1 or 2, wherein the longitudinal edges the metal strip in the circumferential direction to each other at a distance are fixed, which corresponds to at least one wall thickness of the metal strip. Composite pipe according to one of claims 1 to 3, in which an inner layer ( 6 ) of the metal shell in the region of the edges (z-shape) of the metal strip closely adjoining this in an outer layer ( 5 ) of the metal shell ( 3 ) is transferred. A composite pipe according to any one of claims 1 to 4, wherein the outer peripheral surface of the metal shell (FIG. 3 ) is substantially continuous. Composite pipe according to one of claims 1 to 5, wherein at least one inner side of the metal strip is coated with a thermosetting adhesive or adhesive, so that a cohesive connection between the plastic inner tube ( 2 ) and the metal shell ( 3 ) and / or between an inner layer ( 6 ) and an outer layer ( 5 ) of the metal shell ( 3 ) consists. Composite pipe according to one of the preceding claims, further comprising a plastic outer jacket ( 4 ), which by means of a preferably thermosetting adhesion promoter or adhesive cohesively with an outer layer ( 5 ) of the metal pipe is connected. Composite pipe according to one of the preceding claims, wherein an outer surface of the composite pipe ( 1 ) is continuous and in particular a profile of the composite tube is circular, is. Composite pipe according to one of the preceding claims, wherein the plastic inner pipe ( 2 ) has a diffusion-tight coating on its inside and / or outside. Composite pipe according to one of claims 1 to 9, characterized through its use in heating or sanitary engineering as a conduit for conducting of fluids. Device for producing a plastic-metal composite pipe ( 1 ), which at least one inner tube ( 2 ) made of plastic and a sheathed this metal shell ( 3 ), wherein an inner peripheral surface ( 6 ) of the metal shell ( 3 ) tightly against an outer circumferential surface of the plastic inner tube ( 3 ), the device comprising: - an unwinding device ( 11 ) for removing the plastic inner tube ( 3 ) as an endless tube, the device ( 10 ) passes through at a predetermined speed, - a second unwinding device ( 11 ) for removing the endless metal strip, so that this synchronously with the plastic inner tube ( 3 ), and - a forming device ( 14 - 16 ) for forming the metal strip, so that opposite edges of the metal strip are guided one above the other, that the metal shell is formed over its entire circumference double-layered or as a superimposed double jacket substantially over its entire circumference. Apparatus according to claim 11, wherein the forming device is designed so that the plastic inner tube ( 2 ) when forming the metal strip to the double-layered metal tube ( 3 ) is used as a synchronous mitlaufender bending dome. Apparatus according to claim 11 or 12, further comprising a coating device ( 13 ) to coat at least one side of the metal strip with a thermosetting adhesive or adhesive. Device according to the preceding claim, in which the forming device comprises a heating device ( 15 ), which inductively heats the metal strip passing through the device and formed into the double-layered metal jacket, so that the thermosetting adhesion promoter or adhesive activates the material-locking connection between the plastic inner tube and the metal sheath and / or between an inner layer and an outer layer of the metal sheath becomes. Device according to one of claims 11 to 14, wherein the forming device downstream of the heating device calibration device ( 16 ) to the profile of the composite pipe ( 1 ) to calibrate, so that the plastic inner tube ( 2 ) and the double-layered metal shell ( 3 ) fly tightly and thus favor the bonding process.