EP1827727B9 - Method for the production of a multi-layer pipe - Google Patents

Abstract

Production of a multilayer pipe (5) from sheet steel by a bending roller involving laying individual layers (1,2) on top of each other to form the multilayer material which is then shaped to form the multilayer pipe. During the final phase of pipe shaping by the bending roller and/or a bending machine a material layer which acts as an internal pipe (1) is pressed with a force fit into layer (2) which acts as the external pipe. A INDEPENDENT CLAIM is included for a mulilayer pipe obtained by the above process.

Description

The present invention relates to a method for producing a multilayer pipe. Multilayer pipes are preferably used in case of high requirements against corrosion or abrasion.

Corrosion-resistant pressure vessels or pressure lines can be produced more cost-effectively by using multilayer pipes than solid versions made of appropriate materials. This is achieved by the load sharing on a thin, corrosion-resistant inner layer (e.g., stainless and acid resistant steel) and a high strength, pressure resistant outer layer (eg, fine-block steel). As a result, overall steel consumption can be significantly reduced and a large part of the remaining blast consumption can be shifted to low-cost materials.

Abrasion-resistant pipelines are made possible by the design as a multilayer pipe (such as mechanical bond, see below) in certain grades because materials (eg high-strength steels with high hardness) can be used as the inner layer, which alone or only very difficult to Pipes can be processed.

Other material combinations are possible in a great variety, in principle, the combinability of materials is limited only by the applicable processing techniques.

• vollflächiger metallurgischer Bindung (diese erfordert plattiertes Blech als Ausgangshalbzeug), und
• rein mechanischer Bindung (etwa einer Reibbindung) zwischen Innen- und Außenrohr - vorzugsweise Innen- und Außenblech und ihrer Verschweißung an den Blechkanten-.

When constructing the pipe jacket, a distinction is made between

• full-surface metallurgical bond (this requires plated sheet metal as a starting semi-finished product), and
• purely mechanical bond (such as a friction bond) between inner and outer tube - preferably inner and outer plate and their welding to the Blechkanten-.

The production of such multilayer pipes is carried out according to the prior art as follows:

Such a procedure is through JP-A-60111791 known.

• Zunächst erfolgt die Herstellung eines Verbund-Bleches durch Walz- oder Sprengplattieren,
• dann die Rohrformung nach üblichen Verfahren,etwa vermittels einer Biegewalze oder Biegeprese und
• hernach die Schweißung, wobei die Außenwand des Mehlagenrohres nach den üblichen Verfahren zur Rohrschweißung entsprechend dem verwendeten Werkstoff und die Schweißung der Innenwand als Auftragsschweißung, ebenfalls passend zum Werkstoff erfolgt.

For multi-layer pipes with metallurgical bond between the layers - such as multi-layer pipes made of metal sheets, preferably steel sheets - is used as a starting semi-finished a clad composite sheet of two different (steel) materials use. The multilayer pipe is then produced as follows:

• First, the production of a composite sheet by roll or explosive plating,
• then tube forming by conventional methods, such as by means of a bending roll or bending press and
• thereafter, the welding, wherein the outer wall of the Mehlagenrohres according to the usual method of pipe welding according to the material used and the welding of the inner wall as build-up welding, also fits the material.

The disadvantage of this method according to the prior art, on the one hand in the high cost of the starting semi-finished product and thus of the final product, on the other hand, in a lack of sufficient availability of the starting semi-finished, due to extremely limited production capacity for this purpose in the world So there is to the knowledge of Applicant and the inventor only a few plants for the production of roll-laminated multilayer sheets, such as in Austria and Japan, but for example not a single plant in the Federal Republic of Germany for this purpose. Even systems for explosive cladding are hardly available to the knowledge of the inventor and the applicant. For example, at Dynamit Nobel in Burbach, Germany, one of the few such facilities exists. Also, the manufacturing technique used in this case is very problematic and correspondingly expensive and expensive, it being additionally noted that it is available even for very small production lots at all.

Furthermore, the number of materials that can be processed in this way, limited. For example, certain abrasion-resistant steels can not be used as the inner layer if they are difficult or impossible to weld because of their high carbon content.

• Zwei fertige Rohre werden aus den zu kombinierenden Werkstoffen passgenau gefertigt und ohne Reibung ineinander geschoben, wobei das äußere Rohr eine höhere Streckgrenze aufweisen muß als das innere.
• Durch Expandieren (mechanisch - etwa vermittels eines Expansionsstempels - oder durch Flüssigkeitsdruck, wobei die ineinander liegenden Rohre in ein das Außenrohr umfassendes Gesenk gepreßt werden) wird das Innenrohr unter elastischer Aufweitung des Außenrohrs in das Außenrohr gedrückt. Nach Wegfallen der Expansionskräfte legt sich das Außenrohr wegen der höheren elastischen Rückfederung kraftschlüssig um das Innenrohr.
• Abschließend werden die beiden Werkstoffe an den Stirnseiten verschweißt.

In multi-layer pipes with mechanical binding find as a starting semi-finished more - preferably two - finished pipes use. The method will be explained below with reference to the example of two tubes (in the case of further layers, the leads are to be understood accordingly):

• Two finished tubes are made of the materials to be combined accurately and pushed into each other without friction, the outer tube must have a higher yield strength than the inner.
• By expanding (mechanically - such as by means of an expansion punch - or by fluid pressure, wherein the nested tubes are pressed into a die comprising the outer tube), the inner tube is pressed into the outer tube with elastic expansion of the outer tube. After elimination of the expansion forces, the outer tube sets because of the higher elastic resilience frictionally around the inner tube.
• Finally, the two materials are welded at the ends.

The disadvantage of this method according to the prior art is due to the fact that the outer tube must have a higher yield strength than the inner, otherwise missing the frictional connection with the inner tube causing and therefore required elastic resilience of the outer tube. This is particularly disadvantageous because high-strength valuable materials - such as particularly high-strength steels - as they are preferably particularly favorable for abrasion resistant piping inside the pipe, high or even very high yield strengths and thus are not suitable for this manufacturing process.

It is therefore an object of the present invention starting from the prior art to provide a method for producing a multi-layer pipe, on the one hand seeks to avoid the aforementioned disadvantages, thus does not require roll and / or blast-plated semi-finished, but on the other hand is not subject to the restrictions that the manufacturing Multi-layer pipes according to the prior art with frictional mechanical bonding of layers with each other brings.

This object is achieved by a method for producing a multilayer pipe according to claim 1. Further expedient embodiments emerge from the subclaims.

According to the present invention, the use of rolled and / or blast-plated semifinished product can be avoided by the fact that the respective functioning as an inner tube material layer already during the tube forming in the bending roll and / or the final shaping usually necessary bending machine frictionally in the respective outer tube functioning Material layer pressed and so frictionally held in the respective outer tube and without having to expand the multi-layer pipe and thus to address the disadvantages already mentioned. It should be noted that in some cases, however, a final forming in the bending roll alone is possible, such as shorter bending rolls, which can perform the function of the final shaping of the tube with. In these cases, a bending machine does not participate in the method according to the invention.

As used herein, when referring to a compound along an edge or along a (preferably imaginary) line, it refers to any type of connection along the edge or line, whether that connection is along the entire edge or line or only in sections along the edge or line, or even in single points (such as spot welds), approximately at two points - preferably at the end points of the edge or line - or even at a single point on the edge or on the line.

• wird die erste Verbindung zwischen den Werkstofflagen dadurch geschaffen, daß diese entlang einer der Längs- oder Querkanten der aufliegenden Werkstofflage miteinander verbunden werden, und
• es erfolgt die mindestens eine weitere Verbindung zwischen den Werkstofflagen nach einem bestimmtem Verformungsfortschritt entlang der zweiten Längs- oder Querkante der aufliegenden Werkstofflage.

In a preferred embodiment of the method for producing a multilayer pipe with the aid of a bending roll according to the present invention,

• the first connection between the material layers is created by connecting them along one of the longitudinal or transverse edges of the overlying material layer, and
• There is at least one further connection between the material layers after a certain deformation progress along the second longitudinal or transverse edge of the overlying material layer.

The at least one further connection between the material layers can be created approximately after a deformation progress between 50% and less than 100%.

• mit DA als Außendurchmesser des Außenrohres in mm,
• SA als Wanddicke des Außenrohres in mm,
• SI als Wanddicke des Innenrohres in mm,
• σ_I als Streckgrenze des Innenrohres in N/mm2,
• Z _s als Stauchungszuschlag angegeben in Teilen von Hundert und
• E als Elastizitätsmodul (E-Modul) in N/mm2.

In a further particularly preferred embodiment of the method for producing a double-layer tube as a multi-layer tube with an outer tube and an inner tube by means of a bending roll according to the present invention, the deformation progress results after the at least one further connection between the material layers takes place - here called F _for and in Divided by hundred, preferably approximately as follows $$F_{\mathit{for}}=\left(1-\frac{\frac{{\sigma }_I}{e}\mathit{(}\mathit{THERE}\mathit{-}2\mathit{\cdot }\mathit{SA}\mathit{-}\mathit{SI}\mathit{)}\mathit{\cdot }\mathit{\pi }\cdot \left(Z_s+1\right)}{(\mathit{THERE}\mathit{-}\mathit{SA}\mathit{)}\mathit{\cdot }\mathit{\pi }\mathit{-}\mathit{(}\mathit{THERE}\mathit{-}2\mathit{\cdot }\mathit{SA}\mathit{-}\mathit{SI}\mathit{)}\mathit{\cdot }\mathit{\pi }}\right)\cdot 100$$

• with DA as the outer diameter of the outer tube in mm,
• SA as the wall thickness of the outer tube in mm,
• SI as the wall thickness of the inner tube in mm,
• σ _I as the yield strength of the inner tube in N / mm2,
• Z _s as upset specified in parts of hundred and
• E as elastic modulus (modulus of elasticity) in N / mm2.

The above expression results from the following relationships:

The length of the neutral fiber of the outer tube - here L _nfa , gennant-amounts $${\mathit{L}}_{\mathit{nfa}}=(\mathit{THERE}\mathit{-}\mathit{SA})\cdot \pi$$

The length of the neutral fiber of the inner tube - here called L _nfi - is: $${\mathit{L}}_{\mathit{nfi}}=\left(\mathit{THERE}\mathit{-}2\mathit{\cdot }\mathit{SA}\mathit{-}\mathit{SI}\right)\cdot \pi$$

The displacement of the free sheet edge at 100% _{degree of} deformation of the tube - here called L _fv - is then: $${\mathit{L}}_{\mathit{fv}}\mathit{=}{\mathit{L}}_{\mathit{nfa}}-{\mathit{L}}_{\mathit{nfi}}$$

und die Stauchungslänge zum erreichen der Stauchgrenze zu: $${\mathit{L}}_{\mathit{st}}\mathit{=}{\mathit{\epsilon }}_{\mathit{St}}\mathit{\cdot }{\mathit{L}}_{\mathit{nfi}}\cdot \left(Z_s+1\right)$$

The degree of compression of the inner tube to reach the compression limit - here called ε _St - results in: $${\mathit{\epsilon }}_{\mathit{St}}=\frac{{\sigma }_I}{e}$$

and the compression length to reach the compression limit to: $${\mathit{L}}_{\mathit{st}}\mathit{=}{\mathit{\epsilon }}_{\mathit{St}}\mathit{\cdot }{\mathit{L}}_{\mathit{nfi}}\cdot \left(Z_s+1\right)$$

und in Teilen von Hundert- angegeben: $$F_{\mathit{for}}=\left(1-\frac{{\mathit{L}}_{\mathit{st}}}{{\mathit{L}}_{\mathit{fv}}}\right)\cdot 100.$$

The deformation progress, in which the further connection between the material layers takes place - here called F _for - amounts then (as value between 0 and 1 indicated) approximately: $$F_{\mathit{for}}=1-\frac{{\mathit{L}}_{\mathit{st}}}{{\mathit{L}}_{\mathit{fv}}}$$

and in parts of hundreds: $$F_{\mathit{for}}=\left(1-\frac{{\mathit{L}}_{\mathit{st}}}{{\mathit{L}}_{\mathit{fv}}}\right)\cdot \mathrm{100th}$$

DA

als Außendurchmesser des Außenrohres in mm,

SA

als Wanddicke des Außenrohres in mm,

SI

als Wanddicke des Innenrohres in mm,

σ_I

als Streckgrenze des Innenrohres in N/mm²,

Z _s

als Stauchungszuschlag angegeben in Teilen von Hundert und

E

als Elastizitätsmodul (E-Modul) in N/mm²

auf, so erhält man den eingangs für den Verformungsfortschritt, bei dem die weitere Verbindung zwischen den Werkstofflagen erfolgt, - hier F _for genannt und in Teilen von Hundert angegeben - den eingangs bereits angeführten Ausdruck. Der Stauchungszuschlag berücksichtigt dabei die Fertigungsungenauigkeit in der Fixierung der zumindest einen weiteren Werkstofflagenverbindung, und kompensiert dies so, daß die angestrebte Presskraft des Innenrohres gegen das Außenrohr mindestens erreicht wird.If you solve this expression with:

THERE

as the outer diameter of the outer tube in mm,

SA

as the wall thickness of the outer tube in mm,

SI

as the wall thickness of the inner tube in mm,

σ _I

as yield strength of the inner tube in N / mm ² ,

Z _s

as a compression surcharge given in parts of hundred and

e

as elastic modulus ( modulus of elasticity ) in N / mm ²

On, we obtain the beginning of the deformation progress, in which the further connection between the material layers takes place - here called F _for and given in parts of a hundred - the expression already mentioned at the outset. The compression allowance takes into account the manufacturing inaccuracy in the fixation of the at least one further material layer connection, and compensates for this so that the desired pressing force of the inner tube against the outer tube is at least achieved.

Some examples may illustrate this, with the minimum and maximum, as well as the typical example, relating to the percentage of deformation at which the at least one further bond between the material layers occurs: Table 1: Examples for determining the deformation progress for a further connection of the material layers Given are: Possible minimum Typical example Possible maximum unit Ex.1 Ex. 2 Example 3 DA (diameter of outer tube) mm 406 762 2500 SA (wall thickness of the outer tube) mm 25 20 12 SI (wall thickness of the inner tube) mm 10 3 1 σ _I (yield strength of the inner tube) N / mm ² 100 350 480 Z _s (compression surcharge) (%) 0% 50% 15% E (modulus of elasticity or modulus of elasticity) N / mm ² 210000 210000 210000

The sought sizes are then as follows Table 2: Desired sizes for the examples for determining the deformation progress for a further connection of the material layers from Table 1 For the examples according to Tab. 1, the following quantities are then obtained: Possible minimum Typical example Possible maximum unit Ex.1 Ex. 2 Example 3 Length of the neutral fiber of the outer tube: L _nfs = (DA-SA) * π mm 1,196.9 2,331.1 7,816.3 Length of the neutral fiber of the inner tube: L _nfi = (DA - 2 * SA - SI) * π mm 1,087.0 2,258.8 7,775.4 Displacement of the free sheet edge at 100% forming: L _fv = L _nfa -LO _nfi mm 110.0 72.3 40.8 Degree of compression of the inner tube to reach the compression limit: ε _st = σ _I / (E) (%) 0.05% 0.17% to 0.23% Compression length to reach the compression limit: L _st = ε _st · L _nfi · Z _s mm 12:52 5.65 20.44 Required degree of deformation for the at least one further connection, for example for fixing the second sheet metal edge: F _for = 1-L _st / L _fv (%) 99.5% 92.2% 50.0%

A further preferred embodiment of the method for producing a multilayer pipe by means of a bending roll according to the present invention is characterized in that at least one of the material layers consists of more than one applied element, preferably more than one sheet. The laid-up elements can lie with their longitudinal edge parallel to the longitudinal edge of the underlying material layer, but need not. So it is also possible that they come to rest with their longitudinal edge transverse thereto.

If the elements are parallel with their longitudinal edge-preferably approximately parallel-to the longitudinal edge of the underlying material layer, the first connection between the material layers is preferably created by the elements, preferably sheets, after being placed along their joint, which at the same time each have a longitudinal edge the elements, preferably sheets, forms the resting material layer, with the underlying material layer, preferably the underlying sheet metal, are connected.

This method is particularly suitable for making large diameter, preferably larger than 610 mm (24 ") multilayer pipes of the invention where often the width of available inner layer material strips, preferably steel strips, is insufficient to provide a complete inner layer for such large If two tapes are not sufficient, the process can be continued as desired, in which case three or more elements, preferably metal sheets, are placed.

Preferably, in the method for producing a multilayer pipe by means of a bending roll according to the present invention, the multilayer pipe is closed by welding the outer pipe along the pipe seam and build-up welding of the inner pipe so as to manufacture the multilayer pipe body.

Also, the material layers can be connected to the front sides of the tube, about to prevent the ingress of moisture between the metallurgically yes not fully connected Werkstorfflagen.

A preferred application of the method according to the present invention is the production of double-layer tubes according to the invention, however, the invention is not limited thereto, also three-, four- and more multi-layer pipes according to the invention are hereby basically produced, which is far more difficult according to the prior art if not impossible at all

In a further particularly preferred embodiment of the present invention find sheets, preferably metal sheets and more preferably steel sheets, as a material layer or elements of the material layer use.

Also, in the method for producing a multilayer pipe by means of a bending roll according to the present invention, at least one of the compounds of the Material layers as a weld, which is particularly suitable for the aforementioned metal sheets, preferably steel sheets.

The multilayer pipe obtained by the present erfindungemäßen method may in particular be designed so that a respective inner material layer relative to the respective outer material layer has a higher yield strength or yield strength (see below) than this wherein at least one material layer preferably made of sheet metal, particularly preferably from Sheet steel exists.

A particularly preferred embodiment of a multilayer pipe obtained by the process according to the invention is characterized in that the multilayer pipe is formed as a double-layer pipe, which has two layers of steel sheet, wherein the sheet acting as an inner tube sheet has a high to very high carbon content and thus at least not necessarily weldable is.

The multi-layer pipes thus obtained according to the invention are different in many ways from those of the prior art, but without that these differences must all simultaneously show up in a multi-layer pipe according to the invention and thus could characterize it. Rather, these differences can occur in different combinations with each other, but they do not have to.

Thus, according to the present invention, on the one hand, it is not necessary to use clad sheets (with the disadvantages discussed above of long delivery times and limited availability, as well as high price), but on the other hand multi-layer pipes - in particular double-layer pipes made of sheet steel with high yield strength of the respective material Inner tube are produced at the same time lower yield strength of the material of contrast, the respective outer tube, which is required for such uses of multi-layer pipes, for which it has the highest possible abrasion resistance of the Inner tube arrives, since a high abrasion resistance usually synonymous with a high hardness and this in turn is accompanied by a high yield strength Such multilayer tubes having an inner tube made of a material with higher than or equal yield strength a pipe arranged outside this, but still no full metallurgical Connection of adjacent layers show, can not be produced so far in the prior art; they do not exist yet. On the other hand, they are made possible by the present invention. It should be pointed out that in the case of a non-pronounced yield strength - for example, in cases of increased plastic deformation - instead of the yield strength of the yield strength as the amount of stress a plastic permanent strain under a certain force occurs.

Regardless of this, with the inventive method and multilayer pipes without the use of expensive and poorly available plated (full metallurgically bonded) sheets in almost any large diameters can be produced, which is not yet possible in the prior art, since the necessary expansion by the Dimensions of the expansion punches used or by a necessary in the case of hydraulic expansion force for the uniform molding die enclosing the multi-layer tube to be produced, is limited. In contrast, the bending roll method according to the invention allows multilayer pipes which are not subject to such predetermined limits, since the bending roll, which indeed only forms a shaping at one point of the radius of curvature of the pipe, thus does not limit the diameter of the multilayer pipe according to the invention. This makes it possible, in particular, to produce multilayer pipes without plated metal sheets which exceed the limit given by the current state of the art of approximately 610 mm (24 ") diameter, preferably far.

Also, the present invention first enables the production of multilayer tubes with partial inner layer, i. a cross-sectionally only a partial circle forming inner tube, for example in the form of a gutter insert on the pipe base, which has hitherto also not possible according to the prior art

In this context, it is worth noting that, of course, according to the method of the present invention, pipes in only very small numbers, especially individual pieces are economically produced, which in a case by the prior art in one case by the costly plating and the minimum required production lots and in the other Trap is prevented by the necessary for expanding this purpose specially designed tools and devices.

Fig. 1

eine perspektivisch skizzierte Aufsicht auf zwei aufeinandergelegte, zum Mehrlagenrohr zu kombinierende Werkstofflagen,

Fig. 2

eine perspektivisch skizzierte Aufsicht auf zwei aufeinandergelegte, zum Mehrlagenrohr zu kombinierende Werkstofflagen mit einer ersten Verbindung, vorzugsweise Schweißung zwischen den Werkstofflagen in etwa entlang einer (gedachten) Linie parallel zu einer Längskante der aufliegenden Werkstofflage,

Fig. 3

eine perspektivisch skizzierte Aufsicht auf zwei aufeinandergelegte zum Mehrlagenrohr zu kombinierende Werkstofflagen, wobei hier eine der Werkstofflagen aus zwei in Rohrlängsrichtung aufgelegten Elementen - vorzugsweise Blechen - besteht,

Fig. 3a

zeigt eine weitere perspektivisch skizzierte Aufsicht auf zwei aufeinandergelegte zum Mehrlagenrohr zu kombinierende Werkstofflagen, wobei hier eine der Werkstofflagen, nämlich die aufgelegte Werkstofflage aus mehreren, nämlich einer Vielzahl in Rohrumfangsrichtung aufgelegten Elementen- vorzugsweise Blechen - besteht,

Fig. 4

eine perspektivisch skizzierte Aufsicht auf zwei aufeinandergelegte, zum Mehrlagenzohr zu kombinierende Werkstofflagen, wobei eine der Werkstofflagen aus mehr als einem, nämlich hier zwei aufgelegten Elementen - vorzugsweise Blechen - besteht und hier eine erste Verbindung zwischen den Werkstofflagen dadurch geschaffen wurde, daß die Elemente nach dem Auflegen entlang ihrer Stoßstelle, die zugleich jeweils eine Längskante der Elemente der aufliegenden Werkstofflage bildet mit der darunterliegenden Werkstofflage verbunden, vorzugsweise verschweißt wurden,

Fig. 5

eine perspektivisch skizzierte Sicht in ein erfindungsgemäßes Mehrlagenrohr von einer Stirnseite her während des erfindungsgemäßen Herstellverfahrens, nämlich in dem Verfahrensschritt, wo der hierbei gebildete Mehrlagen-Werkstoff mit Hilfe der Biegewalze (Die Biegewalze selbst ist hier ausgeblendet und daher nicht zu sehenl) zum Rohr geformt wird, wobei durch den Druck der Walzen von oben und unten ständig ein Reibschluss zwischen den Werkstofflagen erzeugt wird und bei der Verformung die noch frei gegeneinander verschiebbaren Teile der Werkstofflagen aufgrund der unterschiedlichen Biegeradien von Innenrohr und Außenrohr sich entsprechend dem Verformungsfortschritt frei zueinander verschieben,

Fig. 6

eine perspektivisch skizzierte Sicht in ein erfindungsgemäßes Mehrlagenrohr von einer Stirnseite her während des erfindungsgemäßen Herstellverfahrens, nämlich in dem Verfahrensschritt, wo nach einem bestimmten Verformungsfortschritt mindestens eine weitere Verbindung zwischen den Werkstofflagen dadurch geschaffen wurde, daß die aufliegende Werkstofflage an zumindest einer weiteren Position miteinander verbunden wurden,

Fig. 7

einen perspektivischen Querschnitt durch ein fertiggestelltes erfindungsgemäßes Mehrlagenrohr mit Innen- und Außenlage,

Fig. 8

einen perspektivischen Querschnitt durch ein Mehrlagenrohr mit Innen- und Außenlage in Detailansicht im Bereich der Schweißnaht.

In the following non-limiting exemplary embodiments will be discussed with reference to the drawings. In this shows

Fig. 1

a perspective sketch outlined on two superimposed, to be combined multi-layer pipe material layers,

Fig. 2

a perspectively outlined top view of two superimposed, to multilayer tube to be combined material layers with a first connection, preferably welding between the material layers approximately along a (imaginary) line parallel to a longitudinal edge of the overlying material layer,

Fig. 3

a perspective outlined top view of two superimposed to multilayer pipe material layers to be combined, in which case one of the material layers of two launched in the tube longitudinal direction elements - preferably sheets - is,

Fig. 3a

shows a further perspective sketched plan view of two superimposed to multilayer pipe to be combined material layers, in which case one of the material layers, namely the applied material layer of several, namely a plurality in the tube circumferential direction launched elements - preferably sheets - is,

Fig. 4

a perspectively outlined top view of two superimposed, to multi-layer pipe to be combined material layers, one of the material layers of more than one, namely here two applied elements - preferably sheets - and here a first connection between the material layers was created by the elements according to Laying along its joint, which at the same time each forms a longitudinal edge of the elements of the overlying material layer connected to the underlying material layer, preferably welded,

Fig. 5

a perspective outlined view into an inventive multilayer pipe from one end face during the manufacturing process according to the invention, namely in the process step where the resulting multilayer material using the bending roll (The bending roll itself is hidden here and therefore not seenl) is formed to the tube , wherein by the pressure of the rollers from above and below constantly a frictional engagement between the material layers is generated and in the deformation, the still freely mutually displaceable parts of the material layers due to the different bending radii of inner tube and outer tube move freely according to the deformation progress,

Fig. 6

a perspectively outlined view into an inventive multi-layer pipe from one end side during the manufacturing process according to the invention, namely in the process step, where after a certain deformation progress at least one further connection between the material layers was created by the overlapping material layer were connected to at least one other position .

Fig. 7

a perspective cross section through a finished inventive multilayer pipe with inner and outer layer,

Fig. 8

a perspective cross section through a multi-layer pipe with inner and outer layer in detail in the weld area.

Fig. 1 shows a perspective sketch outlined on two superimposed, to be combined multi-layer pipe material layers 1, 2nd

Fig. 2 shows a perspective sketch outlined on two superposed, to be combined multilayer pipe material layers with a first compound 3a and 3b - preferably welding (namely at the points 3a, 3b) - between the material layers 1, 2 approximately along a (imaginary) line parallel to a longitudinal edge 4 of the overlying material layer. 1

Fig. 3 shows a perspective sketch outlined on two superposed to multilayer pipe to be combined material layers 1a, 1b, 2, in which case one of the material layers, namely the applied material layer of two launched in the tube longitudinal direction elements 1a, 1b - preferably sheets - consists

Fig. 3a shows a further perspective sketch outlined on two superimposed to multilayer pipe to be combined material layers 1a, 1b, ..., 1n, 2, in which case one of the material layers, namely the applied material layer of a variety, namely a finite number - here called n - of 1a, 1b,... 1n, preferably sheet metal, are made up of elements 1a, 1b,..., 1n deposited in the circumferential direction of the pipe. In the drawing, this is indicated by a dotted line 11 indicated.

The applied elements 1a, 1b ..... 1n lie here with their longitudinal edge 4 transversely to the longitudinal edge of the underlying (= lying down) material layer 2, whereas here with their respective transverse edge 4a parallel to the longitudinal edge of the underlying (= underlying) Material layer 2 lie. Also provided with this arrangement are respective first connections 3a ₁ , 3a ₂ , 3b ₁ , 3b ₂ , 3n ₁ , 3n _{2 of} the elements _{2 a} , ₁ b placed on the material layer ₂ . .... to see 1n here.

Fig. 4 shows a perspective sketch outlined on two superposed, multi-layer tube to be combined material layers 1a, 1b, 2, wherein one of the material layers of more than one, namely here two launched elements 1a, 1b - preferably sheets - and here a compound 3 between the material layers was created by the elements 1a, 1b after laying along its joint, which also forms a respective longitudinal edge of the elements 1a, 1b of the overlying material layer, connected to the underlying material layer 2, preferably welded. Here was this compound 3 along the joint and at the same time longitudinal edge by extending over the entire length of the joint and at the same time longitudinal edge extending closed connection 3, preferably welding. In particular, a partial connection, preferably welding is possible.

Fig. 5 shows a perspective sketched view into an inventive multi-layer pipe 5 from one end side during the manufacturing process according to the invention, namely in the process step where the resulting multilayer material using the bending roll (the bending roll itself is hidden here and therefore not visible) to the pipe 5 is formed, whereby by the pressure of the rollers from top and bottom constantly a frictional engagement between the material layers 1, 2 is generated and during deformation the still freely mutually displaceable parts 1c against 2a, and 1d against 2b of the material layers due to the different bending radii of Inner tube 1 and outer tube 2 move according to the deformation progress freely to each other. The first connection 3a and 3b between the two fabric layers 1, 2 took place here already at two points 3a, 3b, which lie along a (imaginary) line parallel to a longitudinal edge of the forming inner tube 2 - namely at the local end points. In the region of this first connection 3a and 3b of the material layers 1, 2, however, they can no longer shift relative to each other due to their connection 3a and 3b, but instead remain fixed relative to one another.

Fig. 6 shows a perspective sketched perspective in an inventive multilayer pipe 5 from one end side during the manufacturing process according to the invention, namely in the process step, where after a certain deformation progress at least one further connection - here two other compounds - 6a and 6b, here in each case as a continuous or partially executed , Welded seam, between the material layers 1, 2 was created by the fact that the overlying material layer 1 at at least one other position - were connected to each other - here at two other positions. Following this, then, the multi-layer tube 5 can be formed using the bending roller and / or bending machine to the end (no longer visible), which now no longer move against each other during this final shaping the material layers due to the further connections 6a and 6b, causing the respective material layer 1, 1c, 1d acting as an inner tube is non-positively pressed into the respective material layer 2, 2a, 2b acting as an outer tube

Fig. 7 shows then a perspective cross section through a finished inventive multilayer pipe 5 with inner layer (also called inner tube, inner tube, inner plate, etc.) 1 and outer layer (also outer tube, outer tube, base plate, etc. called) 2, wherein the multilayer tube 5 by a weld 7 of the outer tube 2 was closed along a pipe seam 8 and a build-up weld 9 of the inner tube 1.

Fig. 8 shows a perspective cross section through a multilayer pipe after Fig. 7 with inner layer 1 and outer layer 2 in a detailed view in the region of the two weld seams 7, 9.

Claims (15)

1. A method for manufacture of a multi-layer pipe (5) by means of a bending roller, where

   - individual material layers (1, 2) to be combined into the multi-layer pipe (5) are put onto each other,

   - subsequently a first connection (3, 3a and 3b, 3a₁ and 3a₂, 3b₁ and 3b₂, 3n₁ and 3n₂) between the material layers (1, 2) is created by connecting them to each other,

   characterised in that

   - the thus formed multi-layer material is shaped into a pipe (5) by means of the bending roller with a constant friction-tight connection being created between the material layers (1, 2) as a result of the pressure of the rollers from the top and from the bottom, and during shaping, the portions (1c, 1d, 2a, 2b) of the material layers (1, 2), which can still shift freely against other, shifting freely to each other in accordance with the shaping progress due to the different bend radii of internal pipe (1) and external pipe (2)

   - after a definite shaping progress at least one other connection (6a, 6b) is created between the material layers (1, 2) by connecting them to each other in at least one other position, and

   - the multi-layer pipe (5) is then finish-shaped by means of the bending roller and/or bending machine, with the material layers (1, 2) shifting no more against each other now during this finish-shaping, so that as a result, the material layer (1) acting as an internal pipe is pressed non-positively into the material layer (2) acting as an external pipe.
2. A method for manufacture of a multi-layer pipe (5) by means of a bending roller according to claim 1, characterised in that the material layer (1) acting as an internal pipe constitutes a graduated circle in cross-section in the finished multi-layer pipe (5).
3. A method for manufacture of a multi-layer pipe (5) by means of a bending roller according to claim 2, characterised in that the material layer (1) acting as an internal pipe that constitutes a graduated circle in cross-section in the finished multi-layer pipe (5) forms a channel at the base of the multi-layer pipe.
4. A method for manufacture of a multi-layer pipe (5) by means of a bending roller according to claim 1, 2 or 3, characterised in that first connection between the material layers (1, 2) is created by connecting them to each other approximately alongside a longitudinal edge (4) or transverse edge (4a) of the material layer positioned above (1), or approximately alongside a line parallel to it.
5. A method for manufacture of a multi-layer pipe (5) by means of a bending roller according to claim 1 - 4, characterised in that the at least one other connection (6a, 6b) between the material layers (1, 2) occurs after a definite shaping progress approximately alongside a second longitudinal edge (4) or transverse edge (4a) of the material layer above (1, 1a, 1b, 1n), or approximately alongside a line parallel to it.
6. A method for manufacture of a multi-layer pipe (5) by means of a bending roller according to claim 1 - 5, characterised in that

   - the first connection between the material layers (1, 2) is created by connecting them to each other alongside one of the longitudinal edges (4) or transverse edges (4a) of the material layer (1) above, and

   - the at least one other connection (6a, 6b) occurs between the material layers (1, 2) after a definite shaping progress alongside the second longitudinal edge or transverse edge of the material layer (1) above.
7. A method for manufacture of a multi-layer pipe (5) by means of a bending roller according to one of the claims 1-6, characterised in that the at least one other connection (6a, 6b) between the material layers (1, 2) is created after a shaping progress between 50 % and less than 100 %.
8. A method for manufacture of a double-layer pipe (5) as a multi-layer pipe with an external pipe (2) and an internal pipe (1) by means of a bending roller according to one of the claims 1 - 6, characterised in that the at least one other connection (6a, 6b) between the material layers (1, 2) is created after a shaping progress of approximately F_for (indicated in parts per cent) with F_for resulting as follows : $$F_{\mathit{for}}=\left(1-\frac{\frac{{\sigma }_I}{E}\mathit{(}\mathit{DA}\mathit{-}2\mathit{\cdot }\mathit{SA}\mathit{-}\mathit{SI}\mathit{)}\mathit{\cdot }\mathit{\pi }\cdot \left(Z_s+1\right)}{(\mathit{DA}\mathit{-}\mathit{SA}\mathit{)}\mathit{\cdot }\mathit{\pi }\mathit{-}\mathit{(}\mathit{DA}\mathit{-}2\mathit{\cdot }\mathit{SA}\mathit{-}\mathit{SI}\mathit{)}\mathit{\cdot }\mathit{\pi }}\right)\cdot 100$$

   

   with

   DA being the external diameter of the external pipe in mm,

   SA being the wall thickness of the external pipe in mm,

   SI being the wall thickness of the internal pipe in mm,

   σ_I being the yield point of the internal pipe in N/mm²,

   Z_s being the upsetting allowance indicated in parts per cent and

   E the Young's modulus in N/mm².
9. A method for manufacture of a multi-layer pipe (5) by means of a bending roller according to one of the claims 1 - 8, characterised in that at least one of the material layers (1, 2) comprises more than one element (1a, 1b, 1n) positioned above
10. A method for manufacture of a multi-layer pipe (5) by means of a bending roller according to claim 9, characterised in that the elements are placed with their longitudinal edge approximately parallel to the longitudinal edge of the material layer below, and the first connection (3) between the material layers (1,2) is created by the elements (1a, 1b) after their positioning on top alongside their joining location, which at the same time constitutes each a longitudinal edge of the elements of the material layer (1a, 1b) on top, being connected with the material layer below.
11. A method for manufacture of a multi-layer pipe (5) by means of a bending roller according to one of the claims 1 to 10, characterised in that the multi-layer pipe (5) is closed by means of welding (7) of the external pipe (2) alongside the pipe seam (8) and deposition welding (9) of the internal pipe (1).
12. A method for manufacture of a multi-layer pipe (5) by means of a bending roller according to one of the preceding claims 1-11, characterised in that the material layers (1, 2) are connected at the pipe front (5).
13. A method for manufacture of a multi-layer pipe (5) by means of a bending roller according to one of the preceding claims 1-12, characterised in that as a multi-layer pipe (5) a double-layer pipe is manufactured.
14. A method for manufacture of a multi-layer pipe (5) by means of a bending roller according to one of the preceding claims 1 - 13, characterised in that plates are used as a material layer (1, 2) or elements (1a, 1b, 1n) of the material layer (1).
15. A method for manufacture of a multi-layer pipe (5) by means of a bending roller according to one to of the preceding claims 1 - 14, characterised in that at least one of the connections (3, 3a and 3b, 3a ₁ and 3a₂, 3b₁ and 3b₂, 3n₁ and 3n₂, 6a, 6b) of the material layers (1, 2) is performed as a welding.

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