CN108136465B

CN108136465B - Method for producing a multilayer composite pipe

Info

Publication number: CN108136465B
Application number: CN201680051094.2A
Authority: CN
Inventors: B.科利
Original assignee: Inoex GmbH
Current assignee: Inoex GmbH
Priority date: 2015-09-02
Filing date: 2016-09-01
Publication date: 2020-04-21
Anticipated expiration: 2036-09-01
Also published as: CN108136465A; DE102015114637B3; WO2017036462A1

Abstract

The invention relates to a method for producing a multilayer composite pipe having: an intermediate metal shut-off layer for shutting off the passage of gases, an inner layer which guides the medium and an outer protective layer, wherein the metal shut-off layer is designed as a shut-off layer or a metal tube which is closed in the peripheral direction, the inner layer is extruded into the tubular shut-off layer by means of an inner main extruder, wherein the inner starting material is guided to the inner main extruder and the outer protective layer is extruded onto the shut-off layer by means of an outer main extruder, wherein the outer starting material is guided to the outer main extruder. Provision is made here for the length and weight of the composite pipe to be adjusted, wherein the adjustment comprises at least the following steps: presetting a total throughput as a sum of an inner throughput of inner starting material and an outer throughput of outer starting material; the outer diameter of the protective layer is adjusted by measuring the outer diameter and adjusting the outer throughput for the protective layer.

Description

Method for producing a multilayer composite pipe

Technical Field

The present invention relates to a method and apparatus for manufacturing a multilayer composite pipe.

Background

The composite tube has an intermediate metal gas barrier (Sperrschicht), in particular an oxygen barrier, for example made of aluminum, the intermediate metal barrier thus forming a metal tube which reliably blocks the passage of gas in the radial direction, an inner medium-conducting layer is formed radially inside the barrier or the metal tube, which inner medium-conducting layer is, for example, designed as a water-conducting inner layer for aqueous (w ä ssrige) media or is also designed for conducting other liquids, such as gasoline, solvents, etc., an outer protective layer is applied to the metal barrier or the metal tube.

The manufacture of the entire plastic metal composite pipe can be carried out in a single-stage manufacturing process in which a metal strip is deformed and in most cases welded longitudinally with a safe overlap (sicherties ü berlappt), butt-welded with no overlap in some cases (stumpf), to construct the metal pipe, and the inner adhesion-promoting layer and the inner layer are extruded directly next into the metal pipe and the extrusion of the outer adhesion-promoting layer and the protective layer onto the metal pipe is continued.

In the single-stage production method, the metal deformation and the extrusion of the further layers are therefore carried out in short succession by forming the metal strip into a tube around the extrusion tool and, for example, overlap welding and the two inner layers are extruded (einextrudier) into the newly formed metal strip and the two outer layers are extruded (autofrudier) onto the newly formed metal tube.

EP 0353977 a1, EP 0581208 a1 and WO 00/44546 a1 describe such composite tubes or methods and devices for their manufacture.

The forming and overlap welding of the metal strip are particularly critical to the production process. Fluctuations in the forming process lead to different widths of the overlap and thus to fluctuations in the diameter of the metal tube.

A modified method for manufacturing plastic metal composite pipes is described in EP 1986798 a 1. Here, the metal layer is not produced from a formed and welded strip, but is extruded seamlessly by pressing a metal wire through a forming nozzle. Also here, the production process is subject to fluctuations which lead to fluctuations in the dimensions of the metal layer.

Since the inner and outer layers are additionally extruded in a single-stage production process in a production line (inline) with a fixedly set throughput, the fluctuating diameter of the metal layer correspondingly means fluctuations in the overall pipe diameter as the wall thickness of the individual layers continues to fluctuate. Fluctuations in the outer diameter of the metal tube lie, for example, in the range of up to 0.2mm, which can lead to very high rejects in the production process with an allowed overall tolerance of 0.15mm for the outer diameter of the composite tube.

However, the measurement and inspection in process technology in such a single-stage method is very problematic here. The metal layer normally prevents measuring the inner layer except by means of a consumable method such as X-ray inspection.

Basically, the weight (gravimetriche) assignment is known when introducing plastic starting materials for plastic pipes, in particular also multilayer plastic pipes. This weight distribution generally regulates the mass throughput of the extruder, i.e. the rate of conveyance of the starting material. Thus, in connection with the measurement or adjustment of the speed of the production pipe, length-weight adjustment (meter-weight adjustment) is possible.

In addition, external calibration for fixing the outside diameter of the tube is known.

In metal-reinforced plastic pipes, however, external calibration is not possible, since the rigid metal layer does not allow the plastic melt to be placed against the calibration site. In order to remain within the permitted tolerances for the outer and inner diameters of the pipe despite fluctuations in the diameter of the metal layer located inside, the inner and outer protective layers of the guide medium are usually designed as a compromise with the wall thickness in the middle of the tolerance zone. Here, however, more material is used than is necessary, and even stronger fluctuations in the diameter of the metal layer lying on the inside also always lead to tolerances which are above or below the permissible tolerances for the composite pipe.

Disclosure of Invention

The object of the present invention is to provide a method and a device for producing a multilayer composite pipe, which allow reliable and nevertheless material-saving production.

This object is achieved by a method for producing a multilayer composite pipe and an apparatus for producing a multilayer composite pipe,

the multilayer composite pipe has: an intermediate metal cut-off layer for cutting off the passage of gas, an inner layer for guiding the medium and an outer protective layer,

wherein the metal cut-off layer is configured as a cut-off layer which is closed in the circumferential direction,

extruding the inner layer through an inner main extruder into a tubular metal shut-off layer, wherein an inner starting material is conducted to the inner main extruder, and

extruding the outer protective layer onto the metal shut-off layer through an outer main extruder, wherein an outer starting material is introduced to the outer main extruder,

wherein the content of the first and second substances,

providing an adjustment of the length and weight of the composite pipe, wherein the adjustment has at least the following steps:

presetting a total throughput as a sum of an inner throughput of the inner starting material and an outer throughput of the outer starting material,

adjusting the outer diameter of the outer protective layer by measuring the outer diameter and adjusting the outer throughput for the outer protective layer,

determining the inner throughput from the total throughput and the adjusted outer throughput, and

adjusting the internal throughput.

The device has:

-a control mechanism for receiving the measurement signal and outputting an adjustment signal,

-a deformation mechanism for accommodating and deforming the metal semi-finished product for producing a tubular metal cut-off layer closed in the circumferential direction,

an extrusion tool having an inner main extruder for extruding an inner layer of a guide medium into the metal shut-off layer and an outer main extruder for extruding an outer protective layer onto the metal shut-off layer in a single-stage extrusion process,

-measuring means for measuring the outer diameter of the outer protective layer and outputting a measurement signal to the control means,

wherein the control mechanism is configured for manipulating the internal rotational speed of the internal extruder conveying unit of the internal main extruder by means of an internal regulating signal for adjusting the internal throughput of internal starting material,

wherein the control mechanism is configured for manipulating an outer rotational speed of an outer extruder conveying unit of the outer main extruder by an external adjustment signal for adjusting an outer throughput of outer starting material,

wherein the control mechanism is configured to adjust a length weight of the composite tube,

wherein the adjustment has at least the following steps:

adjusting the internal throughput.

Composite pipes that can be made by the method are also provided.

The method according to the invention can be carried out in particular with the device according to the invention. The device according to the invention can be provided in particular for carrying out the method according to the invention.

According to the invention, an adjustment method is therefore provided in which the outer throughput for forming the outer protective layer and the inner throughput for forming the inner layer of the guide medium are adjusted or allocated, wherein the throughputs are included in the adjustment.

Here, the adjustment of the outer protective layer is firstly carried out by means of a measurement which is technically well-implementable for the measurement of the outer diameter of the outer protective layer, which therefore advantageously also represents the outer diameter of the entire composite pipe. The outer throughput of the outer protective layer is adjusted by measuring the outer diameter and adjusting the outer throughput.

Subsequently, the inner throughput of the inner layer is matched depending on the previously adjusted current outer throughput. The internal theoretical throughput for the inner layer can therefore be formed and adjusted at present depending on the adjustment of the outer protective layer, respectively. The internal throughput can be adjusted by means of regulation or also simple difference formation (diffrenzenbildung).

According to the invention, it is thus apparent that a reliable and reduced regulation of the material usage is already achieved by reliable measuring variables, i.e. the outer diameter and the inner and outer throughputs of the outer protective layer or of the composite pipe, which can be measured in particular (laser) optically, while direct measurement of the inner layer, for example by means of X-rays and other costly methods is not necessary.

Several advantages are achieved according to the invention. The overall length weight of the composite pipe can be kept small and reliably adjusted according to the invention. When the wall thickness of the outer protective layer increases, the reduction in the wall thickness of the inner layer can thus be adjusted accordingly directly in order to match the overall length weight, and conversely when the wall thickness of the outer protective layer decreases, the increase in the wall thickness of the inner layer can be adjusted. Thus, material consumption, weight and cost are reduced. Furthermore, limited (enge) manufacturing tolerances can also be complied with and production rejects avoided.

Furthermore, the method and the device according to the invention can be carried out with little effort, since the dispensing, in particular the weight dispensing, is generally customary for the inner and outer protective layers in general, and the associated measuring-technical effort is not required for the throughput determined. Likewise, measuring the outer diameter by means of, for example, (laser) optical measuring means is not associated with a large consumption. Rather, by means of such optical measurements, it is also possible to determine and check the out-of-roundness or ovality by means of measurements at a plurality of circumferential positions, so that further quality assurance is achieved.

The composite pipe constructed according to the invention is therefore also distinguished in particular by a high constancy of the weight of its layers and in particular of its overall length. The composite pipe can therefore be constructed with thin walls with predetermined tolerances or can also be produced with very limited tolerances.

According to one advantageous embodiment, the total throughput for the two main extruders (i.e. of the inner main extruder for extruding the inner layer and of the outer main extruder for extruding the outer protective layer) is first determined and specified as a preset. This total throughput can be determined in particular directly from the required total length weight (total meter weight) of the composite pipe. The value of the length weight of the metal tube is known by the metal strip introduced, for example, in a metal tube produced by overlap welding of the metal strip (irrespective of the width of the overlap). From the outer throughputs set in the first control method by measuring the outer diameter of the protective layer, a respective current setpoint value for the inner throughputs can then be formed as the difference between the preset total throughput and the current outer throughput, which is then adjusted or also adjusted, for example, by controlling the rotational speed of the worm of the inner main extruder.

The adjustment of the inner and outer throughputs can be carried out in different embodiments. One embodiment uses gravimetric dosing by a weighing device that weighs successive starting materials and thus determines the rate of introduction as mass per time. The introduction can take place in free fall, so that starting material, for example plastic powder, plastic granules or plastic pellets, falls out of a storage container via a corresponding weighing device into an inner or outer main extruder, the rotational speed of which is continuously adjusted in such a way that the desired inner and outer throughputs are precisely achieved. In such an embodiment, the total throughput may thus be set to the total transport rate of the dimensions of mass per time (Dimension).

According to another embodiment, a melt pump (Schmelzepumpen) may be used for both main extruders, said melt pump being used between the respective extruder worm screw and the extruder nozzle (annular gap nozzle for extruding the annular material). Such melt pumps can be designed in particular as gear pumps and are distinguished by a very constant volume throughput independent of the rotational speed and therefore also by a mass throughput per revolution.

If the same melt pump is used for the inner main extruder and the outer main extruder, the total throughput can therefore be set to the total rotational speed, i.e. the sum of the inner and outer rotational speeds; otherwise, melt pumps with different throughputs per revolution can also be used, taking into account the matching factor for determining the total throughput. The melt pump is therefore actuated by the control signal of the control unit and adjusts the corresponding rotational speed. It is recognized here that the additional weighing, for example, of adjusting the rotational speed of the extruder worm without throughput, may be insufficient if necessary, since the mass throughput thereof is not sufficiently independent of the rotational speed, but is influenced by the stagnation pressure (staudrock) in front of the extruder nozzle or the backflow of the extruder nozzle.

It is furthermore recognized that in many construction variants it is not necessary to include adhesion-promoting layers in the first place, since they do not contribute to the overall length weight to a relevant extent, and variations in the metal tube also do not have an effect on the variation in its wall thickness over the relevant range.

Alternatively or in a special embodiment, however, an adjustment of the adhesion-promoting layer can be included together.

Drawings

The invention is explained in more detail below in terms of some embodiments with the aid of the figures. Wherein:

FIG. 1 shows a perspective cross-sectional view of a five-layer composite tube according to an embodiment of the present invention;

FIG. 2 shows an apparatus for manufacturing a composite pipe;

FIG. 3 shows a flow diagram of a method for manufacturing a composite pipe according to the invention; and is

Fig. 4 shows an embodiment modified with respect to fig. 2.

Detailed Description

The five-layer composite pipe 1 has, according to fig. 1 (from inside to outside), an inner layer 2 of, for example, polyethylene, which guides water, which guides the medium, an inner adhesion promoter layer 3 applied to the inner layer 2 and having a thickness of, for example, b3= 0.15-0.2mm, an oxygen barrier layer 4 of metal, in particular aluminum, applied to the inner adhesion promoter layer 3, an outer adhesion promoter layer 5 applied to the barrier layer 4, and an outer protective layer 6 of, for example, polyethylene, applied to the outer adhesion promoter layer 5. The

layers

2, 3, 4, 5, 6 are thus each tubular in shape themselves, with an outer diameter d2, d3, d4, d5, d6 and a layer thickness (wall thickness) b2, b3, b4, b5, b 6.

The adhesion-promoting

layers

3 and 5 serve to increase the adhesion of the intermediate metal barrier layer 4 to the respective plastic layer, i.e. the inner layer 2 or the protective layer 6, and are constructed, for example, from a polyethylene-based material. The inner layer 2 can also be made of polyamide, for example, when the composite pipe 1 is used for relatively aggressive liquids, for example, as a gasoline line.

The cut-off layer 4 is in the illustrated illustration designed as a longitudinally welded tube with a safety overlap;

additional layers

2, 3, 5 and 6 are extruded.

This production is advantageously carried out in a single-stage production process using the device 8 shown in fig. 2 for producing the five-layer composite tube 1.

The aluminum deformation takes place in a deformation mechanism 10 to which a metal semifinished product 11, for example an aluminum strip, is continuously introduced. Here, the metal blank 11 is formed around the extrusion tool 14 shown in fig. 2 as a metal tube, i.e. as a tubular shut-off layer 4. If a metal strip is used, it is either formed with the overlap 13 and welded in the weld seam 12 or only butt-welded with the weld seam 12 without the overlap 13.

The inner adhesion-promoting layer 3 and the inner medium-conducting layer 2 are extruded into the newly formed tubular shut-off layer 4. The external adhesion-promoting layer 5 and the external protective layer 6 are extruded onto the tubular cut-off layer 4.

The extrusion tool 14 is schematically illustrated in fig. 2 by dashed lines and has a single extruder 14-i for each

layer

2, 3, 5, 6, i =2, 3, 5, 6, each having an extruder worm 15-i and a nozzle 16-i with an annular gap, i =2, 3, 5, 6, in order to form the

layer

2, 3, 5, 6 as an annular layer surrounding the shut-off layer 4. The nozzles for the two outer plastic layers and for the two inner plastic layers are usually each embodied as a coextrusion nozzle in a staggered manner (ineiner).

This single stage manufacturing process is subject to fluctuations and tolerances. It is already technically critical to form the metal tube from the semi-finished metal product 11. Therefore, in the case of forming and welding a metal strip, variations in the width of the overlap 13 or the width of the weld 12 lead to fluctuations in the diameter d4 of the shut-off layer 4, i.e. the metal tube. Since the

inner layers

2 and 3 and the

outer layers

5 and 6 are additionally extruded (zuextrudier) in the process in the production line, fluctuations in the diameter d4 of the stop layer 4 (without matching the layer thickness b2 of the inner layer 2 and b6 of the protective layer 6) lead correspondingly to fluctuations in the overall tube diameter d6 (outer diameter of the protective layer 6) when the overall wall thickness of the composite tube 1 fluctuates simultaneously.

What is achieved by the device according to fig. 2 and the method according to fig. 3 is that the length weight (weight in meters, mass per length unit) LM1 of the composite pipe 1 is adjusted within the permissible adjustment deviation, wherein the length weight LM6 of the outer protective layer 6 is reduced and the length weight LM2 of the inner layer 2 is increased with the larger diameter d4 of the cut-off layer 4.

Accordingly, in the case where the diameter d4 of the cutoff layer 4 is small, the length-weight LM6 of the outer protective layer 6 is increased and the length-weight LM2 of the inner layer 2 is decreased.

The main extruders 14-2 and 14-6 of the inner layer 2 and the outer protective layer 6 are assigned a weight ration. According to fig. 2, the internal intake material 20 (for example plastic granules, plastic powder or plastic pellets) is removed from the storage reservoir 21 and introduced via an internal weighing device 24 into the internal main extruder 14-2.

The internal weighing device 24 of the internal main extruder 14-2 determines the introduction rate sr2, for example as a time introduction quantity per mass of time (kg/h), and outputs a first measurement signal S1 to the control mechanism 30. The incoming material 20 is then introduced into the internal main extruder 14-2, contained by it, melted, conveyed via its extruder worm 15-2 to its nozzle 16-2 and extruded. The rotational speed of the extruder worm 15-2 determines the introduction rate sr 2.

The corresponding applies to the external main extruder 14-6: the starting material 35 is introduced from the storage reservoir via the external weighing device 42 into the external main extruder 14-6, wherein the external weighing device 42 outputs a second measurement signal S2 to the control mechanism 30.

The control mechanism 30 in turn outputs a first regulating signal S3 to the inner extruder worm 15-2 and a second regulating signal S4 to the outer extruder worm 15-6 for adjusting the rotational speed and thus one of the rates of introduction sr2 and sr6, respectively.

Furthermore, the measurement of the structured composite pipe 1 (for example as a multiaxial outer diameter measurement, in particular as a laser measurement) is carried out with the optical measuring device 50 at preferably three or more locations distributed in the circumferential direction, so that not only the average outer diameter d6 of the outer protective layer 6, but also, if appropriate, ovality or unroundness can be determined. The measuring means 50 thus output a third measuring signal S5 to the control means 30, said third measuring signal S5 being used to correct the length and weight LM6 of the outer protective layer 6.

In this embodiment, the adhesion-promoting

layers

3, 5 are not adjusted together. The construction of the adhesion-promoting layer is carried out by means of secondary extruders 16-3 and 16-5. This can be done without using a weight ration by adjusting the constant rotational speed of the extruder worms 15-3 and 15-5. When the weight distribution is also used for the secondary extruders 16-3 and 16-5, the starting material 33 of the internal adhesion-promoting layer 3 is introduced into the internal secondary extruder 16-3 via the weighing device 22 or is taken up by the internal secondary extruder 16-3 in accordance with the rotational speed of its extruder worm 15-3, and the measurement signal S6 is output to the control unit 30, which in turn outputs the control signal S7 to the internal secondary extruder 16-3. The constant introduction rate sr3 of starting material 33 is preferably preset and kept constant via the control signal S7. Accordingly, the starting material 34 of the external adhesion-promoting layer 5 is introduced into the external secondary extruder 14-5 by means of the weighing device 43 and the measurement signal S8 of the weighing device 43 is output to the control mechanism 30, which in this embodiment adjusts the constant introduction rate sr5 by means of the regulating signal S9 to the external secondary extruder 14-5.

Fig. 3 shows the steps of the adjustment method. After the start in step St0, the preset for the total introduction rate n, which is formed as the sum of the internal introduction rate n2 for the inner main extruder 14-2 and the external introduction rate n6 for the outer main extruder 14-6, is made in St 1:

n = n2 + n6。

the adjustment of the outer diameter d6 of the composite tube 1 is then carried out in steps St2 to St 5. For this purpose, in a step St2, the current outer diameter d6_ ist of the composite pipe 1 or the outer protective layer 6 is first measured with the aid of the measuring device 50 and subsequently evaluated in a decision step St 3. If the outer diameter d6_ ist is smaller than the lower limit value d6_ u according to the left branch 3a, the external introduction rate n6 in kg/S to the external main extruder 14-6 is subsequently increased according to step St4 by controlling the rotational speed for the extruder worm 15-6 by means of the second control signal S4; if, on the other hand, it is determined from the right branch 3b that the determined outer diameter d6 is greater than the upper limit value d6_ o, the external introduction rate n6 is reduced in step St5 by means of the second control signal S4. In both cases, the outer diameter d6_ ist is then measured again in step St2 and then evaluated in a decision step St 3.

If in step St3 it is determined from the lower branch 3c that the current outer diameter d6_ ist lies within the limit values d6_ u, d6_ o, then in steps St6 to St9 a matching of the internal introduction rate n2 for the internal main extruder 14-2 to the currently adjusted external introduction rate n6 is carried out according to n2 = n-n 6.

This is shown in fig. 3 as an adjustment of the introduction rate n 2.

For this purpose, in a step St6, a setpoint value n2_ soll for the internal introduction rate n2 of the internal main extruder 14-2 is first determined from the (angelestzten) total introduction rate n set in a step St1 and the external introduction rate n6 set in a step St2 to St5 from n2_ soll = n-n6_ ist, with n6 as the currently set external introduction rate n2_ soll is then set, in particular adjusted, in steps St7, St8 and St9 again during the return (in R ü ckf ü hrung auf) to a step St 6:

if it is measured in step St7 that the internal introduction rate n2_ ist by the internal main extruder 14-2 is too small, the internal introduction rate n2 of the internal main extruder 14-2 is increased according to step St8 according to the left branch; whereas if it is determined in step St7 that the internal introduction rate n2 of the internal main extruder 14-2 is excessively large, the internal introduction rate n2 is subsequently decreased according to step St 9; the method is returned to step St6 in each case. Thus, in step St7, a comparison is made as to whether or not

n2_u>n2_ist>n2_o，

Where this condition is met, the method is then reset (zur ü ck ges gensetzt) before step St 2.

Therefore, steps St6 to St9 can also be presented in principle in a simplified manner as difference formation n2 = n-n 6.

By presetting the total introduction rate n in step St1, the total length weight or the total meter weight of the entire composite pipe 1 can thus be constantly maintained.

An increase in the outer layer thickness (wall thickness) b6 of the outer protective layer 6 thus directly leads to a reduction or reduction in the inner layer thickness b2 of the inner medium-guiding layer 2 and vice versa.

Fig. 4 shows an alternative embodiment to fig. 2, according to fig. 4, the internal and external throughputs of the starting

materials

20, 35 to the main extruders 14-2 and 14-6 are adjusted, but via melt pumps 60, 61 which are installed between the extruder worm 15-2 or 15-6 and the extruder nozzle (annular gap nozzle) 16-2 or 16-6, such melt pumps 60, 61 preferably operate with a constant melt precompression of the extruders and are distinguished by a very constant volume throughput per revolution, independent of the rotational speed, i.e. also by a mass throughput per revolution in the case of a known or back-calculated (zur ü ckgerechner) melt density.

Thus, the melt pumps 60, 61 according to the second embodiment are each actuated via the internal control signal S3 and the external control signal S4 in such a way that the respective rotational speeds rs2, rs6 of the melt pumps are set.

In the same embodiment of the melt pumps 60 and 61, it is possible, according to the flowchart in fig. 3, to provide, in step St1, instead of the total introduction rate n, a total rotational speed rs, which is expressed as the sum of the internal rotational speed rs2 of the internal melt pump 60 of the internal main extruder 14-2 and the external rotational speed rs4 of the melt pump 61 of the external extruder 14-6:

rs = rs2 + rs6，

thus, in the flowchart of fig. 3, subsequently in the first control loop of steps St2 to St5, the outer rotational speed rs6 is set as a control variable in order to set the outer diameter d6 within the permissible tolerance range, and subsequently in steps St6 to St9 the inner rotational speed rs2 = rs-rs6 is adapted.

If plastics with different densities ρ, i.e. an inner density ρ 2 of the inner layer 2 and an outer density ρ 6 of the outer layer 6, are used for the inner layer 2 and the outer layer 6, this can be taken into account in both embodiments by means of the correction factors ρ 2/ρ 6.

Further embodiments may also include adjustments of the

adhesion promotion layers

3 and 5 in the modifications to fig. 2 and 4, respectively.

It is important for the function of the

adhesion promoters

3 and 5 that the thickness of the

adhesion promoters

3, 5 lies within a certain theoretical range, typically between 0.1 and 0.2mm, too thin a traction promoter does not ensure sufficient adhesion between the layers, while an excessively thick traction promoter carries the risk of adhesion failure in the adhesion promoter for this reason, for example, the

adhesion promoters

3 and 5 do not match proportionally with the changes of the protective layer 6 and the inner layer 2 guiding the medium, conversely it is advantageous that the

adhesion promoters

3 and 5 always have the same thickness (St ä rke) (thickness) b3 or b5 irrespective of the position of the

adhesion promoters

3 and 5 in the composite tube 1, i.e. more material is used when the adhesion promoters are displaced outwards and less material is used when one of the

adhesion promoters

3, 5 is displaced inwards.

According to a first embodiment, a more precise adjustment of the adhesion promoter layers 3 and 5 can be carried out with calculation of the position of the metal layer 4 in the composite pipe, as described below as a variant of the embodiment of fig. 2 and 3. For this purpose, it is provided that the adhesion promoter has a density very similar to the material used for the outer layer 6 and the inner layer 2. This is the case for most of the low density linear polyethylenes (LLDPE) or polyethylenes with improved heat resistance (PE-RT) used for these use cases and adhesion promoters constructed chemically on this basis.

Instead of the throughputs n6 and n2, the throughputs of the two outer layers na and the two inner layers ni with the length weights LMa and LMi (in kg/m) depending therefrom are considered in the control loop according to fig. 2, with:

na = n5 + n6

ni = n2 + n3

and

LMa = LM5 + LM6 = （n5 + n6）/v

LMi = LM2 + LM3 = （n2 + n3）/v

where v is the withdrawal speed of the composite pipe 1.

The exact position of the metal layer in the composite pipe can be continuously calculated using the material usage for the outer layer na determined by the regulating circuit described in fig. 2. The outer diameter d6 of the composite pipe 1 is known from the measuring means 50 which continuously take measurements. Using the length weight LMa and the material density ρ, the outer diameter d4 of the metal layer 4 (equal to the inner diameter di5 of the adhesion-promoting layer 5) can be calculated:

it can therefore be easily calculated which length weight LM5 and thus which throughput n5 can be adjusted by weight measurement (Gravimetrie) of the secondary extruder 14-5 in the case of the preset layer thickness b5 of the external adhesion-promoting layer:

the required length weight LM6 for the protective layer 6 and thus also the throughput n6 are thus calculated:

LM6 = LMa-LM5

since at the same time the outer diameter d3 of the internal adhesion-promoting layer 3 can be calculated from the known thickness b4 of the metal layer 4:

d3 = d4-b4

the length weights LM3 and LM2 and thus the throughputs n3 and n2 of the two

inner layers

3 and 2 can be determined in a similar computational manner with a preset thickness b3 of the internal adhesion-promoting layer 3.

Claims

1. Method for manufacturing a multilayer composite pipe (1) having: an intermediate metal blocking layer (4) for blocking the passage of gas, an inner layer (2) for guiding the medium and an outer protective layer (6),

wherein the metal shut-off layer (4) is designed as a shut-off layer which is closed in the peripheral direction,

extruding the inner layer (2) through an inner main extruder (14-2) into a tubular metal shut-off layer (4), wherein an inner starting material (20) is conducted to the inner main extruder (14-2), and

extruding the outer protective layer (6) onto the metal shut-off layer (4) by means of an outer main extruder (14-6), wherein an outer starting material (35) is introduced into the outer main extruder (14-6),

it is characterized in that the preparation method is characterized in that,

-providing an adjustment of the length-weight (LM 1) of the composite pipe (1), wherein the adjustment has at least the following steps:

presetting a total throughput (n, rs) as the sum (St 1) of an inner throughput (n 2, rs 2) of the inner starting material (20) and an outer throughput (n 6, rs 6) of the outer starting material (35),

adjusting the outer diameter (d 6) of the outer protective layer (6) by measuring the outer diameter (d 6) and adjusting the outer throughput (n 6, rs 6) for the outer protective layer (6) (St 2, St3, St4, St 5),

determining the internal throughput (n 2, rs 2) (St 6) from the total throughput (n, nm) and the adjusted external throughput (n 6, nm 6), and

adjusting the internal throughput (n 2, rs 2) (St 6, St7, St8, St 9).

2. Method according to claim 1, characterized in that the inner starting material (20) of the inner layer (2) and the outer starting material (35) of the outer protective layer (6) are each a plastic material.

3. Method according to claim 1 or 2, characterized in that for the construction of the metal shut-off layer (4) a metal strip is continuously deformed into a closed tube and is longitudinally wound with overlap and connected in the overlapping region (13) of the edges of the metal strip.

4. Method according to claim 1 or 2, characterized in that for the construction of the metal shut-off layer (4) a metal strip is continuously deformed into a closed tube and is longitudinally wound butt-wise and connected in the butt-wise region of the edges of the metal strip.

5. Method according to claim 1 or 2, characterized in that, for the construction of the metal shut-off layer (4), a metal semi-finished product (11) is extruded into a seamless tube as a result of the pressing by means of a deformation means (10).

6. The method according to claim 1 or 2,

the total throughput (n, rs) is preset in the following manner:

-first presetting the total length weight (LM) of the composite pipe (1),

-forming the sum of the length weights (LM 2, LM 6) of the inner layer (2) and the outer protective layer (6) from the total length weight (LM) taking into account the length weight (LM 4) of the metal shut-off layer (4),

-determining the total throughput (n, rs) from the sum of the length weights (LM 2, LM 6) of the inner layer (2) and the outer protective layer (6), the density of the solid inner starting material (20) of the inner layer (2) and the solid outer starting material (35) of the outer protective layer (6), and the withdrawal speed (v) of the composite pipe (1).

7. The method according to claim 1 or 2, characterized in that the method for manufacturing the multilayer composite pipe (1) is single-stage, wherein the inner layer (2) and the outer protective layer (6) are applied during or immediately after the construction of the metal shut-off layer (4) as a closed pipe.

8. The method according to claim 1 or 2, characterized in that the internal introduction rate (n 2) of the inner starting material (20) into the inner main extruder (14-2) is adjusted to an internal throughput (n 2) and the external introduction rate (n 6) of the outer starting material (35) into the outer main extruder (14-6) is adjusted to an external throughput (n 6),

wherein the total throughput (n) is formed as a total introduction rate (n) which is formed as the sum of the internal introduction rate (n 2) and the external introduction rate (n 6).

9. Method according to claim 8, characterized in that the internal starting material (20) is introduced to the internal main extruder (14-2) by means of an internal weighing device (24), wherein the internal introduction rate (n 2) is adjusted by means of an internal regulating signal (S3) by manipulating the rotational speed of the internal extruder conveying unit.

10. Method according to claim 8, characterized in that the external starting material (35) is introduced to the external main extruder (14-6) by means of an external weighing device (42), wherein the external introduction rate (n 6) is adjusted by means of an external regulating signal (S4) by manipulating the rotational speed of the external extruder conveying unit.

11. Method according to claim 1 or 2, characterized in that an inner melt pump (60) and an outer melt pump (61) are provided between an extruder conveying unit and the extruder nozzles (16-2, 16-6) of the inner main extruder (14-2) and the outer main extruder (14-6), respectively, wherein the inner throughput is adjusted to an inner rotational speed (rs 2) of the inner melt pump (60) and the outer throughput is adjusted to an outer rotational speed (rs 6) of the outer melt pump (61), and the total throughput (rs) is formed as the sum of the outer rotational speed (rs 6) and the inner rotational speed (rs 2).

12. Method according to claim 1 or 2, characterized in that the adjustment of the internal throughput (n 2, rs 2) is set as a differential forming or closed-loop control, wherein an internal theoretical throughput (n 2_ soll, rs2_ soll) (St 6) is first determined from the total throughput (n, rs) and the external throughput (n 6, rs 6) adjusted in a first closed-loop control of the outer diameter (d 6) of the outer protective layer (6),

the current internal actual throughput (n 2_ ist, rs2_ ist) is then compared with the internal setpoint throughput (n 2_ soll, rs2_ soll) (St 7).

13. Method according to claim 1, characterized in that an internal adhesion-promoting layer (3) is extruded onto the inside of a metal cut-off layer (4) formed into the tube, the inner layer (2) is extruded onto the internal adhesion-promoting layer (3), and/or

An external adhesion-promoting layer (5) is extruded onto the metal cut-off layer (4), and the external protective layer (6) is extruded onto the external adhesion-promoting layer (5).

14. Method according to claim 13, characterized in that the internal adhesion promoting layer (3) and/or the external adhesion promoting layer (5) are not matched or changed when adjusting the total length weight (LM).

15. Method according to claim 13, characterized in that said internal adhesion promoting layer (3) and/or said external adhesion promoting layer (5) are adjusted together when adjusting the total length weight (LM).

16. Method according to claim 15, characterized in that the external starting material (35) is introduced to the external main extruder (14-6) by means of an external weighing device (42), the internal adhesion-promoting layer (3) and the external adhesion-promoting layer (5) being adjusted to a preset wall thickness (b 3, b 5) in such a way as to be selected from

-an outer diameter (d 6) of the outer protective layer (6) measured with a measuring means (50),

-an introduction rate for the outer protective layer (6) and the outer adhesion-promoting layer (5) determined by the outer weighing device (42, 43), and

-the extraction speed (v) of the composite pipe (1)

Determining the current position of a metal shut-off layer (4) in the composite pipe (1),

wherein, starting from the outer diameter (d 6) of the composite pipe (1) and the inner diameter (d 3) of the metal shut-off layer (4), further layer structures of the composite pipe (1) are calculated with the measured outer diameter (d 6), the predetermined wall thicknesses (b 3, b 5) and the predetermined total length weight (LM 1) of the internal adhesion promoter layer (3) and the external adhesion promoter layer (5).

17. Method according to claim 1 or 2, characterized in that the measurement (St 1) of the outer diameter (d 6) is carried out as an optical measurement of the outer diameter (d 6) of the constructed composite pipe (1).

18. The method of claim 1, wherein the metal shut-off layer is a metal tube.

19. The method according to claim 12, characterized in that the internal actual throughput (n 2, rs 2) is subsequently matched depending on the comparison (St 8, St 9).

20. Method according to claim 2, characterized in that the inner starting material (20) of the inner layer (2) and the outer starting material (35) of the outer protective layer (6) are the same plastic material.

21. A method according to claim 3, characterized in that the metal strip is an aluminium strip.

22. A method according to claim 3, characterized in that the metal strip is welded longitudinally in a weld seam (12).

23. The method of claim 4, wherein the metal strip is an aluminum strip.

24. Method according to claim 4, characterized in that the metal strip is welded longitudinally in a weld seam (12).

25. Method according to claim 5, characterized in that said semi-finished metal product (11) is an aluminium wire.

26. Method according to claim 5, characterized in that the deformation means (10) is a nozzle.

27. The method according to claim 7, characterized in that the inner layer (2) and the outer protective layer (6) are applied by means of an extrusion tool (14) with extrusion nozzles (16-2, 16-6) configured as annular gaps, wherein a closed tube of the metal shut-off layer (4) is shaped around the extrusion tool (14).

28. The method according to claim 9, wherein the internal weighing device (24) is an internal weighing device.

29. The method according to claim 10, wherein the external weighing device (42) is an external gravimetric weighing device.

30. Method according to claim 17, characterized in that the measurement (St 1) of the outer diameter (d 6) is carried out by means of a plurality of sites distributed in the circumferential direction for taking out unroundness.

31. Method according to claim 9, characterized in that the internal extruder conveying unit is an extruder worm (15-2).

32. Method according to claim 10, characterized in that the external extruder conveying unit is an extruder worm (15-6).

33. Method according to claim 11, characterized in that the extruder conveying unit is an extruder worm (14-2, 14-6).

34. The method of claim 17, wherein the optical measurement is a laser optical measurement.

35. The method according to claim 5, characterized in that the semi-finished metal product is a metal strip.

36. Composite pipe (1) manufactured by a method according to any one of claims 1-35.

37. Apparatus (8) for manufacturing a multilayer composite pipe (1), said apparatus having:

-control means (30) for receiving the measurement signals (S1, S2, S5, S6, S8) and outputting adjustment signals (S3, S4, S7, S9),

-a deformation mechanism (10) for accommodating a metal semi-finished product (11) and deforming the metal semi-finished product (11) for producing a tubular metal cut-off layer (4) which is closed in the peripheral direction,

-an extrusion tool (14) having an inner main extruder (14-2) for extruding a medium-conducting inner layer (2) into the metal shut-off layer (4) and an outer main extruder (14-6) for extruding an outer protective layer (6) onto the metal shut-off layer (4) in a single-stage extrusion process,

-measuring means (50) for measuring the outer diameter (d 6) of the outer protective layer (6) and outputting a measurement signal (S5) to the control means (30),

wherein the control mechanism (30) is configured for manipulating the internal rotation speed of the internal extruder conveying unit (15-2) of the internal main extruder (14-2) by means of an internal adjustment signal (S3) for adjusting the internal throughput of the internal starting material (20),

wherein the control mechanism (30) is configured for manipulating an outer rotational speed of an outer extruder conveying unit (15-5) of the outer main extruder (14-6) by means of an outer adjustment signal (S4) for adjusting an outer throughput of outer starting material (35),

wherein the control mechanism (30) is configured for adjusting the length weight (LM 1) of the composite pipe (1),

wherein the adjustment has at least the following steps:

presetting a total throughput (n, rs) as the sum of an inner throughput (n 2, rs 2) of the inner starting material (20) and an outer throughput (n 6, rs 6) of the outer starting material (35),

adjusting the outer diameter (d 6) of the outer protective layer (6) by measuring the outer diameter (d 6) and adjusting the outer throughput (n 6, rs 6) for the outer protective layer (6),

determining the inner throughput (n 2, rs 2) from the total throughput (n, nm) and the adjusted outer throughput (n 6, nm 6), and

adjusting the internal throughput (n 2, rs 2).

38. The apparatus of claim 37, wherein the metal blank is a metal strip.