EP2285508B1 - Production-optimized method for producing a multilayered tube - Google Patents

Abstract

A process for producing a multilayer pipe (5) with the aid of a plate forming machine, in which individual layers of material (1, 2) to be combined to form the multilayer pipe (5) are laid one on top of the other, at least one of the layers of material (1) consisting of more than one laid-on element (1a, 1b), after that, a first connection (3a, 3b), respectively, is then created between the bordering elements of the overlying layer of material (1a, 1b) and the adjacent layer of material (2), the multilayer material formed in this way is formed into the pipe (5) and, during the deformation, the edges (4a, 4b) of the elements (1a, 1b) of the overlying layer of material (1a, 1b) that are still freely displaceable with respect to one another can move freely toward one another in accordance with the extent to which deforming has progressed, on account of the different circumferential lengths of the inner pipe (1a, 1b) and the outer pipe (2), then, after deforming has progressed to a certain extent, these edges (4a, 4b) of the elements (1a, 1b) of the overlying layer of material (1a, 1b) that are moving toward one another butt against one another, and then the multilayer pipe (5) is formed to completion with the aid of the plate forming machine, the edges (4a, 4b) of the elements (1a, 1b) of the overlying layer of material (1a, 1b) then no longer being able to move freely toward one another during this final forming, as a result of which the layer of material (1a, 1b) respectively acting as the inner pipe is pressed with a force fit into the layer of material (2) respectively acting as the outer pipe.

Description

The present invention relates to a production-optimized 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 much of the remaining steel consumption can be shifted to low-cost materials.

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

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 sheet and their welding at the sheet edges -.

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 disadvantage of this method according to the prior art is firstly the high cost of the starting semifinished product and thus also of the end product, but on the other hand also a lack of sufficient availability of this semifinished product due to extremely limited production capacity for this purpose in the world. 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 im letzten Falle 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. Der Nachteil dieses Verfahrens nach dem Stand der Technik liegt darin begründet, daß das äußere Rohr eine höhere Streckgrenze aufweisen muß als das innere, da ansonsten die den Kraftschluß mit dem Innenrohr hervorrufende und daher erforderliche elastische Rückfederung des Außenrohres fehlt. Dies ist insbesondere deshalb nachteilig, weil hochfeste Werkstoffe
• etwa besonders hochfeste Stähle -, wie sie vorzugsweise für abrasionsbeständige Rohrleitungen im Inneren des Rohres besonders vorteilhaft sind, hohe oder sogar sehr hohe Streckgrenzen aufweisen und sich damit für dieses Herstellungsverfahren nicht eignen.

In multi-layer pipes with mechanical bonding found in the older art 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 statements 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, in the latter case, the nested tubes are pressed into a die comprising the outer tube), the inner tube is pressed with elastic expansion of the outer tube into 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 the lack of adhesion to the inner tube causing and therefore required elastic resilience of the outer tube. This is particularly disadvantageous because high-strength materials
• For example, particularly high-strength steels - as they are preferably particularly advantageous for abrasion-resistant piping inside the pipe, have high or even very high yield strengths and thus are not suitable for this manufacturing process.

• einzelne zum Mehrlagenrohr zu kombinierende Werkstofflagen aufeinandergelegt, und
• der so gebildete Mehrlagen-Werkstoff mit Hilfe der Biegewalze zu einem Mehrlagenrohr geformt, wobei in der Endphase der Rohrformung in der Biegewalze eine jeweilig als Innenrohr fungierende Werkstofflage kraftschlüssig in eine jeweilig als Außenrohr fungierende Werkstofflage gepresst wird.

Meanwhile, however, other procedures from the WO 2006/066814 A1 known, which do not have these disadvantages and are used to produce a multilayer pipe with mechanical bond between the material layers by means of a bending roll. Here are

• individual layers of material to be combined with the multi-layer pipe stacked on top of one another, and
• the multilayer material thus formed is formed into a multilayer pipe with the aid of the bending roll, wherein in the final phase of pipe forming in the bending roll, a respective material layer functioning as an inner pipe is pressed non-positively into a material layer acting as an outer pipe.

With the aid of this method multilayer pipes can be produced which do not require rolled and / or blast-plated semi-finished products, but on the other hand are not subject to the restrictions which the production of multi-layer pipes according to the aforementioned prior art with frictional mechanical bonding of layers with each other.

The use of rolled and / or blast-plated semifinished product is avoided by first creating a first joint between the layers of material, such as a weld, and thereafter the respective layer of material acting as an inner tube during tube forming in the bending roll by attaching it after a certain deformation progress - Pressed further connection between the material layers frictionally in each functioning as an outer tube material layer and is frictionally held in the respective outer tube and without having to expand the multilayer tube and thus to address the above-mentioned expansion method disadvantages.

Nevertheless, this method has the technical production disadvantage that it is necessary to create a further connection between the material layers during the tube forming in the bending roll after a certain deformation progress, which is usually done by welding. For this connection, it is therefore necessary to interrupt the tube forming in order to connect the two material layers together at this further point. For this purpose, the still unfinished pipe must be removed from the bending roll and then created the connection, so in general, the weld can be applied. Alternatively, it can also be welded in the bending roll, which however blocks it during this time. Then, the tube blank (also called slot tube) can be re-introduced into the bending roll to continue the local manufacturing process. Such a procedure is extremely time-consuming and therefore represents a significant production cost disadvantage.

• einzelne zum Mehrlagenrohr zu kombinierende Werkstofflagen aufeinandergelegt werden, wobei eine als jeweiliges Außenrohr fungierende Werkstofflage ein Grundblech bildet, das in etwa entlang seiner beiden Längskanten oder in etwa parallel hierzu jeweils eine, vorzugsweise aufgeschweißte, Anschlagkante aufweist und die aufliegende Werkstofflage lose zwischen diese Anschlagkanten zu liegen kommt, und
• der so gebildete Mehrlagen-Werkstoff mit Hilfe der Biegewalze zu einem Mehrlagenrohr geformt wird, wobei die jeweilige als Innenrohr fungierende Werkstofflage zwischen die Anschlagkanten geklemmt und in der Endphase der Rohrformung in der Biegewalze die jeweilige als Innenrohr fungierende Werkstofflage hierdurch kraftschlüssig in die jeweilig als Außenrohr fungierende Werkstofflage gepresst wird.

The WO 2006/066814 A1 However, it also teaches a method in which

• individual material layers to be combined to form multilayer pipe are stacked, wherein a material layer acting as a respective outer tube forms a base plate, which has a stop edge preferably approximately along its two longitudinal edges or approximately parallel thereto, and the resting material layer lies loosely between these stop edges comes, and
• the multilayer material formed in this way is formed into a multilayer pipe with the aid of the bending roll, the respective material layer acting as inner pipe being clamped between the abutment edges and in the final phase of pipe forming in the bending roll the respective material layer functioning as inner pipe thereby frictionally engaging in the respective outer pipe Material layer is pressed.

According to this embodiment of the WO 2006/066814 A1 Thus, as the respective inner layer, it is also possible to use materials such as particularly high-strength steels which are difficult or impossible to weld. Here too, the material layer acting as an inner tube is already pressed into the bending roll in the bending roll in a force-fitting manner into the respective material layer functioning as an outer tube and thus held frictionally in the respective outer tube without a connection, such as a weld to be created requirement. Therefore, a time- and cost-intensive interruption of the tube forming process in the bending roll is also not required here. However, this manufacturing process in turn has the disadvantage that in this case the pipe inner layer is not completely closed inwardly, since a part of the pipe inner circumference is formed by the on the respective base plate, so the respective outer material layer, attached stop edges, which leads to here the beneficial effects of the tube inner layer, such as corrosion or abrasion resistance can not occur. This disadvantage can not be solved easily by a build-up welding in this area, as a weld between the material of the stop edge and the inner layer in this process, which wants to avoid welding between outer and inner layer just out of the question.

It is therefore an object of the present invention starting from the prior art according to the WO 2006/066814 A1 to provide a method for producing a multi-layer pipe, which requires neither an interruption of the tube forming process for material layer connection nor a subsequent incorporation of material parts.

This object is achieved by a method having the features of claim 1.

In this method according to the present invention, the interruption of the tube forming process in the sheet metal forming machine - ie in the bending roll - thereby avoided that at least two elements that later form the inner layer, initially, ie before the tube forming process, edge side with the later forming the outer layer Material layer connected, so usually welded to this, be. During the tube forming process, eg in the bending roll, the free ends of these elements then move towards each other due to the different bending radii (or circumferential lengths, which means the same thing) of the inner and outer tubes and eventually hit one another. Since at this time already a curvature of the sheet has been used to a pipe, the edges of the abutting layers do not jump from each other, but remain abutting, but they - assuming a smooth edge shaped - a, with increasing deformation progress increasing strength exert on the material inner layer, with which this is pressed against the outer layer. It should be noted that the method according to the invention is designed so that it ensures that from the moment in which the initially still freely mutually displaceable edges of the inner layer sheets abut, the tube to be formed at each point, on the inner and outer layer on each other, already arched. That is, the tube to be formed at each point, on the inner and outer layer on each other has a finite radius (ie nowhere there has an infinite radius). This can be achieved, for example with respect to the majority of the tubular body, preferably by sufficient bending before abutting the displaceable edges of the inner layer elements, which can be done for example by suitable dimensioning and / or positioning of the elements of the inner layer. Also, this (possibly also in addition) - preferably in the edge region, so the area of the later to be closed pipe longitudinal seam comes close - means a previously made bending of the pipe to be formed material layers can be achieved.

In this way, an interruption of the molding process - for example, for further welding of the material layers - to form a full-surface material inner layer of the material provided for this purpose inside the pipe no longer required.

The first connection between the material layers is created by connecting them along approximately one of the longitudinal or transverse edges of the overlying material layer or approximately along a line parallel thereto, but along the future pipe longitudinal seam. The applied elements can thus 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. However, the connection with the material layer below is always along or parallel to the future pipe longitudinal seam.

In this connection, it should be noted that when this text is used herein to refer to a connection along an edge or along a (preferably imaginary) line only, it means any type of connection along the edge or line, whether or not it is Connection along the entire edge or line or only in sections along the edge or line or even in single points (such as spot welds), for instance at two points - preferably at the end points of the edge or line - or even at a single point at the point Edge or on the line.

The material layer functioning as an inner tube can also form a partial circle in the finished multilayer tube, which can be achieved by covering the elements of the overlying material layer, which later form the inner tube layer, only a part of the surface of the material layer which later forms the outer layer. while it is nevertheless important to ensure that they still encounter each other in the course of the tube forming process with their then free ends and so the inner is pressed into the outer layer.

Preferably, the material layer functioning as an inner tube and forming a partial circle in cross-section in the finished multilayer tube forms a groove at the foot of the multilayer tube.

After completion of the slotted tube, so after completion of the essential tube forming process, such as in the bending roll, then another connection, preferably welding between the material layers and / or the abutting edges of the elements of the overlying material layer can be done, in particular to close this butt joint tight here. An interruption of the actual molding process is not required for this purpose. Rather, such a step takes place only after completion of the actual tube forming process. Nor is it necessary to incorporate a further material inner layer strip for this purpose. Rather, a simple weld is sufficient here. In cases where it does not depend on the total tightness of the abutting edge - for example, if only an increased abrasion resistance of the inner layer is required - can be even completely ignored by this weld for sealing.

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

With regard to the force with which the inner layer is to be pressed against the outer layer, be on the already from the WO 2006/066814 A1 referenced geometric and physical conditions, wherein

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 / mm2,

Z _s

as a compression surcharge given in parts of hundred and

e

as elastic modulus (modulus of elasticity) in N / mm2

Use finds. According to those already in the WO 2006/066814 A1 conditions mentioned are - depending on the desired pressing force - the size of the elements of the overlying material layer (ie the later inner layer) and the position of the first connections between the elements of the overlying material layer and the adjacent material layer (ie the material layer, the outer layer usually later forms).

The length of the neutral fiber of the outer tube - here called L _afa - is: $$L_{\mathit{nfa}}=\left(\mathit{THERE}-\mathit{SA}\right)\cdot \pi$$

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

The displacement of the free sheet edges of the elements of the overlying material layer (the later inner layer) is then at 100% degree of deformation of the tube - here called L _fr -: $${\mathit{L}}_{\mathit{fv}}\mathit{=}{\mathit{L}}_{\mathit{nfa}}\mathit{-}{\mathit{L}}_{\mathit{nfi}}$$

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

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

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

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

The deformation progress - here called F _for - at which the free sheet edges of the elements of the overlying material layer should abut each other - if one wants to reach a maximum pressing force - is then (given as value between 0 and 1) approximately: $$F_{\mathit{for}}=1-\frac{L_{\mathit{st}}}{L_{\mathit{fv}}}$$

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

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 Verformungsfortschritt, bei dem die freien Blechkanten der Elemente der aufliegenden Werkstofflage (also der späteren Innenlage) aneinanderstoßen sollen, so man eine maximale Preßkraft erreichen will, durch den folgenden Ausdruck: $$F_{\mathit{for}}=\left(1-\frac{\frac{{\sigma }_I}{E}\cdot \left(\mathit{DA}-2\cdot \mathit{SA}-\mathit{SI}\right)\cdot \pi \cdot \left(Z_s+1\right)}{\left(\mathit{DA}-\mathit{SA}\right)\cdot \pi -\left(\mathit{DA}-2\cdot \mathit{SA}-\mathit{SI}\right)\cdot \pi }\right)\cdot 100$$

If you solve this expression

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 deformation progress, at which the free sheet edges of the elements of the overlying material layer (ie the later inner layer) should abut, if one wants to achieve a maximum compressive force, by the following expression: $$F_{\mathit{for}}=\left(1-\frac{\frac{{\sigma }_I}{e}\cdot \left(\mathit{THERE}-2\cdot \mathit{SA}-\mathit{SI}\right)\cdot \pi \cdot \left(Z_s+1\right)}{\left(\mathit{THERE}-\mathit{SA}\right)\cdot \pi -\left(\mathit{THERE}-2\cdot \mathit{SA}-\mathit{SI}\right)\cdot \pi }\right)\cdot 100$$

The compression allowance takes into account the manufacturing inaccuracy in the fixation of at least one other material layer connection, and compensates for this so that the desired pressing force of the inner tube is at least achieved against the outer tube.

In practice, if you want to form a complete inner tube from the inner layer of material and at the same time strives for the maximum achievable pressing force by means of the method according to the invention - with two resting elements that later form the inner layer -, the resting elements along first weld the longitudinal edges of the later forming the outer layer material layer and select these (the later inner layer forming) elements of their size and geometry forth so that between their free edges a gap remains, which closes in the course of the tube forming process and then the two then abutting Edges are encountered by the yet to be completed further tube forming process only insofar as it allows the compression limit of the material of the future inner layer.

Preferably, in the method for producing a multilayer pipe by means of the method 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 complete the multilayer pipe body.

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

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.

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 according to the present invention, at least one of the joints of the material layers is preferably used as a weld, which is particularly suitable for the aforementioned metal sheets, preferably steel sheets.

As Blechumformmaschine is about a bending roll, for example, a three-roll bending machine, but also a press / die assembly, such as in the context of known from the prior art UOE (U-shapes, O- forms, expand) -Rohrformungsverfahrens (see UOE Method for example: Hiersig, Heinz M., Encyclopedia Mechanical Engineering, Heidelberg 1997, p. 704f , for keyword "Längsnabt-Großrohrherstellung ") or the so-called JCO-tube forming method is suitable. However, it should be noted that according to the method according to the present invention - depending on the material combination - may need to dispense with the last step of expansion, if this in turn due to the yield ratio of the materials of each inner to outer layer, the compression of the material layers against each other again would be very deteriorated.

In the JCO process, the tube is formed by first placing the sheet in a press by means of a sword in the shape of a horizontal J 'and then in that of a horizontal' C '. After that, it then - as in the case of the UOE method - bends into the ' O ' shape.

Due to the fact that the actual tube forming process in the method according to the present invention no longer has to be interrupted for the creation of a further connection between the material layers, the inventive method can now also be operated as a continuous production process in which the material layers to be combined or their elements (each unwound from a wound tape and then continuously superimposed, preferably continuously welded, wherein the subsequent tube forming process also takes place continuously by a Einformstraße, which forms a slit tube from the continuously superimposed layers of material, serves as Blechumformmaschine for tube forming are known from the prior art, as in the US 3,327,383 is described and which is hereby included in the disclosure of the present document.

Fig. 1

eine perspektivisch skizzierte Aufsicht auf zwei aufeinandergelegte zum Mehrlagen- rohr zu kombinierende Werkstofflagen,

Fig. 2

eine perspektivisch skizzierte Sicht in ein - noch nicht fertiggestelltes -Mehrlagenrohr von einer Stirnseite her während des erfindungsgemäßen Herstellverfahrens, nämlich in dem Verfahrensschritt, wo der hierbei gebildete Mehrlagen-Werkstoff mit Hilfe der Blechumformmaschine zum Rohr geformt wird, die Kanten der beiden aufliegenden Elemente aber noch frei gegeneinander beweglich sind,

Fig. 3

eine perspektivisch skizzierte Sicht in ein - ebenfalls noch nicht fertiggestelltes - Mehrlagenrohr von einer Stirnseite her während des erfindungsgemäßen Herstellver- fahrens, nämlich in dem Verfahrensschritt, wo nach einem bestimmten Verformungs- fortschritt die beiden freien Stoßkanten der aufliegenden Elemente nun aneinander stoßen,

Fig. 4

einen perspektivischen Querschnitt durch ein fertiggestelltes Mehrlagenrohr mit In- nen- und Außenlage,

Fig. 5

einen perspektivischen Querschnitt durch ein Mehrlagenrohr mit Innen- und Außen- lage in Detailansicht im Bereich der Schweißnaht, und

Fig. 6

einen kontinuierlichen Rohrformungsprozeß nach der vorliegenden Erfindung in Prinzipdarstellung, bei dem die zu kombinierenden Werkstofflagen oder deren Ele- mente jeweils als aufgewickeltes Band (auch Coil genannt) vorliegen, von dem sie ab- gewickelt und hernach kontinuierlich übereinander gelegt werden,

Fig. 7

die Ausgangssituation des erfindungsgemäßen Verfahrens, wenn die Blechformung vermittels einer UO(E)-Pressen-/Gesenkanordnung ausgeführt wird,

Fig. 8

den Formungsschritt, der ein ,U' formt und zwar vermittels einer Presse (hier nicht dargestellt), die einen entsprechend ausgeformten Stempel nach unten treibt, wo die Werkstofflagen hierdurch gemeinsam in ein Gesenk (hier nicht ebenfalls nicht zu se- hen) getrieben werden, und

Fig. 9

den Formungsschritt der ein ,O', also ein Schlitzrohr ausformt und zwar vermittels einer Presse (hier nicht dargestellt), die zwei als Halbrund ausgeformte Stempel von unten und oben gegen den zu formenden Rohrkörper treibt, wo die Werkstofflagen hierdurch wiederum gemeinsam zu einem - im Querschnitt gesehen - Rund geformt werden.

• Fig. 1 zeigt eine perspektivisch skizzierte Aufsicht auf zwei aufeinandergelegte zum Mehrlagenrohr zu kombinierende Werkstofflagen 1a, 1b, 2, wobei hier eine der Werkstofflagen, nämlich die aufgelegte Werkstofflage 1a,1b, welche später die Innenlage des Mehrlagenrohres bilden soll, aus zwei in Rohrlängsrichtung aufgelegten Elementen 1a, 1b - vorzugsweise Blechen - besteht, welche zu Beginn des erfindungsgemäßen Verfahrens entlang ihrer Längskanten 3a, 3b mit der benachbarten Werkstofflage 2, die später die Außenlage des Rohres bilden soll, erstmalig - vorzugsweise durch eine Schweißnaht - verbunden werden.
• Fig. 2 zeigt eine perspektivisch skizzierte Sicht in ein - noch nicht fertiggestelltes - Mehrlagenrohr 5 von einer Stirnseite her während des erfindungsgemäßen Herstellverfahrens, nämlich in dem Verfahrensschritt, wo der hierbei gebildete Mehrlagen-Werkstoff mit Hilfe der Blechumformmaschine, etwa einer Biegewalze (Die Blechumformmaschine selbst, also etwa die Biegewalze, ist hier ausgeblendet und daher nicht zu sehen!) zum Rohr 5 geformt wird, wobei bei der Verformung die noch nicht mit der benachbarten Werkstofflage 2 verbundenen Kanten 4a, 4b der Elemente 1a, 1b aufgrund der unterschiedlichen Biegeradien von Innenrohr 1, 1a, 1b und Außenrohr 2 sich entsprechend dem Verformungsfortschritt frei gegeneinander verschieben. Die erste Verbindung zwischen den beiden Werkstofflagen 1, 1a, 1b" 2 erfolgte hier bereits an den Kanten 3a, 3b, die entlang der Längskante des sich bildenden Innenrohres 1, 1a, 1b verläuft und die bereits vor dem Rohrformungsprozeß - etwa durch Schweißung - geschaffen wurden. Im Bereich dieser ersten Verbindung 3a und 3b der Werkstofflagen 1, 1a, 1b, 2 aber, können sich diese aufgrund ihrer Verbindung zueinander nicht gegeneinander verschieben, sondern bleiben hier gegeneinander fixiert. Auch ist anzumerken, daß das Rohr auch im oberen Bereich der Darstellung (also in dem Bereich, der auf den noch offenen Rohrschlitz zuläuft) und wo Innen- und Außenlage 1, 1a, 1b, 2 insbesondere auch aufeinanderliegen bereits angerundet ist (der Radius also hier nirgends unendlich ist). Dieser Umstand ist in der perspektivischen Darstellung der Fig. 2 hier möglicherweise nicht so gut zu erkennen, so daß hier diese klarstellende Erläuterung erfolgt.
• Fig. 3 zeigt eine perspektivisch skizzierte Sicht in ein - ebenfalls noch nicht fertiggestelltes - Mehrlagenrohr 5 von einer Stirnseite her während des erfindungsgemäßen Herstellverfahrens, nämlich in dem Verfahrensschritt, wo nach einem bestimmten Verformungsfortschritt die beiden freien Stoßkanten 4a, 4b der aufliegenden Elemente 1a, 1b nun aneinander stoßen. Hierauf folgend kann sodann das Mehrlagenrohr 5 mit Hilfe der Blechumformmaschine zu Ende geformt werden (nicht mehr zu sehen), wobei sich nun während dieser Endformung die Werkstofflagen aufgrund des Aneinanderstoßens der Kanten 4a und 4b nun nicht mehr weiter gegeneinander verschieben, wodurch die jeweilige als Innenrohr fungierende Werkstofflage 1, 1a, 1b kraftschlüssig in die jeweilig als Außenrohr fungierende Werkstofflage 2 gepresst wird. Auch hier ist ebenfalss, wie schon zu Fig. 2 anzumerken, daß das Rohr auch im oberen Bereichder Darstellung (also in dem Bereich, der auf denn noch offenen Rohrschlitz zuläuft) und wo Innen- und Außenlage 1, 1a, 1b, 2 insbesondere auch aufeinanderliegen bereits angerundet ist (der Radius also hier nirgends unendlich ist). Dieser Umstand ist in der perspektivischen Darstellung der Fig. 3 hier möglicherweise nicht so gut zu erkennen, so daß hier diese klarstellende Erläuterung erfolgt.
• Fig. 4 zeigt sodann einen perspektivischen Querschnitt durch ein fertiggestelltes Mehrlagenrohr 5 mit Innenlage (auch Innenrohr, Innenrohrleitung, Innenblech etc. genannt) 1, 1a, 1b und Außenlage (auch Außenrohr, Außenrohrleitung, Grundblech etc. genannt) 2, wobei das Mehrlagenrohr 5 durch eine Schweißung 7 des Außenrohres 2 entlang einer Rorhrnaht 8 und eine . Auftragsschweißung 9 des Innenrohres 1, 1a, 1b geschlossen wurde. Die ersten Verbindungen 3a, 3b zwischen den Lagen 1, 1a, 1b, 2, die bereits vor dem eigentlichen Rohrformungsprozeß erfolgten, sind ebenfalls angedeutet; ebenso ist die Stoßkante der beiden zunächst noch freien Kanten 4a, 4b der beiden Innenlagenelemente 1a,1b zu sehen.
• Fig. 5 zeigt einen perspektivischen Querschnitt durch ein Mehrlagenrohr nach Fig. 4 mit Innenlage 1a,1b und Außenlage 2 in Detailansicht im Bereich der beiden Schweißnähte 3a, 3b, 7, 9.
• Fig. 6 zeigt eine kontinuierliche Rohrformung nach der vorliegenden Erfindung, bei dem die zu kombinierenden Werkstofflagen 1a, 1b, 2 oder deren Elemente jeweils als aufgewickeltes Band (auch Coil genannt) vorliegen, von dem sie abgewickelt und hernach kontinuierlich übereinander gelegt werden. Hiernach erfolgt dann eine ebenfalls kontinuierliche Verschweißung der Lagen am äußeren Rand mittels einer jeweiligen Schweißanlage 10, etwa eines Lasers oder einer Rollennahtschweißmaschine oder einer Punktnahtschweißmaschine oder dergleichen. Auch ein Lichtbogenschweißen ist hier denkbar. Der sodann nachfolgende Rohrformungsprozeß erfolgt abermals kontinuierlich und zwar vermittels einer Einformstraße, die mittels Konturrollen 6 aus den kontinuierlich übereinanderliegenden und am Rande verschweißten Werkstofflagen 1a 1b, 2 ein Schlitzrohr 5 formt und so als Blechumformmaschine dient. Derartige Einformstraßen zur Rohrformung sind etwa aus dem Stand der Technik bekannt, wie er in der US 3 327 383 beschrieben ist. (Anmerkung: In der hier zu sehenden perspektivischen Seitenansicht der Einformstraße sind die Konturrollen aus Darstellungsvereinfachungsgründen als Zylinderdargestellt. Im unteren Teil der Darstellung, die Stationen der Einformstraße im jeweiligen Querschnitt zeigt, sind die Konturrollen 6 hingegen korrekt zu sehen.)

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

Fig. 1

a perspectively outlined top view of two layers of material to be combined to form a multilayer pipe,

Fig. 2

a perspectively outlined view into a - not yet completed -Multlagen tube from one end face during the manufacturing process according to the invention, namely in the process step, where the resulting multilayer material is formed by means of Blechumformmaschine to the tube, but the edges of the two resting elements still are freely movable against each other,

Fig. 3

a perspectively sketched view into a - also not yet finished - multilayer pipe from one end side during the manufacturing process according to the invention, namely in the process step where after a certain deformation progress the two free abutting edges of the resting elements now abut each other,

Fig. 4

a perspective cross section through a finished multi-layer pipe with inner and outer layer,

Fig. 5

a perspective cross section through a multi-layer pipe with inner and outer layer in detail view in the region of the weld, and

Fig. 6

a continuous tube forming process according to the present invention in a schematic representation, in which the material layers to be combined or their elements are each in the form of a wound-up band (also called a coil), from which they are unwound and thereafter placed continuously over one another,

Fig. 7

the starting situation of the method according to the invention, when the sheet metal forming is carried out by means of a UO (E) press / die arrangement,

Fig. 8

the forming step which forms a 'U' by means of a press (not shown here) which drives a correspondingly shaped punch downwards, where the material layers are driven together into a die (not seen here likewise), and

Fig. 9

the forming step of an 'O', ie a slot tube ausformungt by means of a press (not shown here), which drives two shaped as a half round punch from below and above against the tubular body to be molded, where the material layers in turn together to a - im Cross-section seen - round shaped.

• Fig. 1 shows a perspective outlined plan view of two superimposed multilayer pipe to be combined material layers 1a, 1b, 2, in which case one of the material layers, namely the laid-up material layer 1a, 1b, which will later form the inner layer of the multi-layer tube, consisting of two launched in the tube longitudinal direction elements 1a, 1b - preferably sheets - consists, which at the beginning of the inventive method along its longitudinal edges 3a, 3b with the adjacent material layer 2 , which is to form the outer layer of the tube later, for the first time - preferably by a weld - are connected.
• Fig. 2 shows a perspective sketched perspective in a - not yet finished - multilayer tube 5 from one end side during the manufacturing process according to the invention, namely in the process step where the thus formed multilayer material using the sheet metal forming machine, such as a bending roll (The Blechumformmaschine itself, ie the bending roll, is hidden here and therefore not visible!) To the tube 5 is formed, wherein in the deformation not yet connected to the adjacent material layer 2 edges 4a, 4b of the elements 1a, 1b due to the different bending radii of inner tube 1, 1a, 1b and outer tube 2 move freely against each other according to the deformation progress. The first connection between the two material layers 1, 1a, 1b " 2 has already been made here at the edges 3a, 3b, which runs along the longitudinal edge of the forming inner tube 1, 1a, 1b and which has already been created before the tube forming process, for instance by welding In the region of this first connection 3a and 3b of the material layers 1, 1a, 1b, 2, however, they can not shift relative to one another due to their connection to each other, but remain fixed against each other Representation (ie in the area which tapers to the still open tube slot) and where the inner and outer layer 1, 1a, 1b, 2 in particular also on each other is already rounded (the radius is therefore nowhere infinite here.) This circumstance is in the perspective presentation of the Fig. 2 may not be so well recognized here, so here is this clarifying explanation.
• Fig. 3 shows a perspective sketched perspective in a - also not yet finished - 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 , the two free abutting edges 4a, 4b of the overlying elements 1a, 1b now abut each other , Following this, then, the multi-layer tube 5 can be formed using the Blechumformmaschine to the end (no longer visible), now no longer move due to the abutment of the edges 4a and 4b now against each other during this final shaping, whereby the respective inner tube functioning material layer 1, 1a, 1b is pressed non-positively in the respective functioning as an outer tube material layer 2 . Here too is just as good as it already is Fig. 2 It should be noted that the tube is also already rounded in the upper area of the representation (ie in the region which tapers towards the still open tube slot) and where the inner and outer layers 1, 1a, 1b, 2 are also superimposed (the radius is nowhere infinite) is). This circumstance is in the perspective representation of Fig. 3 may not be so well recognized here, so here is this clarifying explanation.
• Fig. 4 shows then a perspective cross-section through a finished multilayer pipe 5 with inner layer (also called inner tube, inner tube, inner plate, etc.) 1, 1a, 1b and Outer layer (also called outer tube, outer tube, base plate, etc.) 2, wherein the multilayer tube 5 by a weld 7 of the outer tube 2 along a Rorhrnaht 8 and a. Hardfacing 9 of the inner tube 1, 1a, 1b was closed. The first connections 3a, 3b between the layers 1, 1a, 1b, 2, which already took place before the actual tube-forming process, are also indicated; Likewise, the abutting edge of the two initially free edges 4a, 4b of the two inner layer elements 1a, 1b can be seen.
• Fig. 5 shows a perspective cross section through a multilayer pipe after Fig. 4 with inner layer 1a, 1b and outer layer 2 in a detailed view in the region of the two weld seams 3a, 3b, 7, 9.
• Fig. 6 shows a continuous tube forming according to the present invention, in which the material layers to be combined 1a, 1b, 2 or their elements are each present as a wound band (also called coil), from which they are unwound and thereafter continuously superimposed. Thereafter, then also a continuous welding of the layers at the outer edge by means of a respective welding system 10, such as a laser or a roller seam welding machine or a Punktnahtschweißmaschine or the like. Arc welding is also conceivable here. The subsequent tube forming process then takes place continuously again by means of an injection molding line which forms a slot tube 5 by means of contour rollers 6 from the material layers 1a 1b, 2 which are continuously superimposed and welded together at the edge and thus serves as a sheet metal forming machine. Such Einformstraßen for tube forming are known for example from the prior art, as shown in the US 3,327,383 is described. (Note: In the perspective view of the forming line seen here, the contour rollers are shown as cylinders for simplicity of illustration.) In the lower part of the illustration showing stations of the forming line in the respective section, the contour rollers 6 are correctly seen.)

The present illustration is intended to clarify the process once more, however, by showing in its upper part the installation serving for this purpose from the side and in the lower part of the illustration at different stations marked by allocation arrows 11 in cross section and, in contrast, the feed direction 12 .

From above, two material layer elements 1a, 1b and from below a material layer 2 therefore run together from above. The material layer elements 1 a, 1 b , which are continuously fed from above as a strip , have a width which is suitable after carrying out the invention Manufacturing process to form the desired inner wall of the pipe to be produced and also in this case to be sufficiently upset by the resulting due to the tube forming pressing force. The details of the design and positioning of the elements of the material layer, which is to come to lie inside, it was already discussed above in the general part of the description here, to which reference should be made at this point. The supplied from below material layer 2 is later used as an outer layer and therefore has the width of the outer circumference of the tube to be produced 5 on.

If the two layers 1a, 1b, 2 to each other, they are each welded at the edge by means of a welding system 10 , so that the elements 1a, 1b of the later inner layer are now each connected to the later outer layer 2 at the outer edge. In contrast, in the center of the material layer 2 forming the later outer wall, the two elements 1a, 1b of the later pipe inner layer still loosely lie with their edges there.

In the following Einformstraße, now from the multilayer sheet 1 a, 1 b, 2 continuously by means of an arrangement of contour rollers 6 (note the note above!) A tube 5 , the above-mentioned still loose edges of the inner material layer elements 1a, 1b now pushed against each other as a result of the different bending radii of outer and inner tube and then close due to the abutment of this up to this point still freely displaceable sheet edges to an inner layer 1. Thereafter, the deformation process to the tube out now so that the two inner layer elements 1a, 1b now be pushed against each other, which now leads to a compression of the inner layer 1 and as a result to the pressure against the further forming outer layer 2 , until finally a slotted tube 5 is formed, which can be closed along the slot by welding. If required, the abutting edges of the two inner layer elements 1a, 1b - for example by means of a laser through the still open slot - may also be welded to one another and / or to the outer material layer 2 beforehand.

Fig. 7 shows the starting situation of the inventive method, when the sheet metal forming is carried out by means of a UO (E) -Pressen- / Gesenkanordnung. The later outer material layer 2 is down here and the two, the subsequent inner layer 1 forming elements 1a, 1b are outside. They were already welded to the lower layer 2 at the edge and there rounded together with the lower layer 2 . Possibly. can the marginal welding of the layers 1a, 1b, 2 but also after the rounding of the edge area done. In the middle of the two resting elements 1a, 1b are still spaced apart.

Fig. 8 then shows the forming step of a, U 'forms by means of a press (not shown here), which drives a correspondingly shaped punch 13 down, where the material layers 1a, 1b, 2 thereby together in a die (not here also not to be driven). Here, the inner material layer elements 1a, 1b with their still freely movable sheet edges - due to the different radii of outer 2 and inner layer 1, 1a, 1b - to each other to move.

Fig. 9 then shows the forming step, which forms an 'O' , ie a slit tube by means of a press (not shown here), the two molded as a half round punch 14, 15 from below and above against the tubular body to be molded, where the material layers 1a , 1b, 2 thereby in turn together to one - seen in cross section - are formed round. Here, too, the inner material layer elements 1a, 1b with their still movable sheet edges due to the different radii of outer and inner layer to each other moves and indeed until they abut and thus forms a continuous inner layer 1 , which now in the further tube forming in the Outer layer 2 is pressed, since the originally free edges of the inner layer elements 1a, 1b now can not move towards each other. As a result of the curvature they do not jump from each other, but lie down against the outer wall 2 .

It should be noted that the method according to the invention can be carried out in a similar manner by means of a press / die arrangement designed for the so-called "JCO" method. Here is then proceeded according to the JCO method, but this modified so that in turn two layers of material, as in the present invention modified UO (E) method are formed. Here, too, the overlying elements 1a, 1b are welded on the edge side to the material layer 2 forming the later outer layer, and then a slot tube is formed by the JCO method. Again, the desired effect according to the invention occurs, in which the initially free sheet edges of the inner layer elements 1a, 1b abut, thereby forming a continuous inner layer 1 and then pressed due to the different bending radii of outer and inner layer against the outer layer 2 .

In all cases, therefore, both the inventively modified RO (E) method, as with the inventively modified JCO process the initially freely movable abutting edges of the two inner sheet members 1a 1b may after their abutting each other and / or be welded to the outer sheet 2 , which can be done for example by the still open slot of the slot tube, preferably by means of a laser welding device.

Claims (14)

1. Process for producing a multilayer pipe (5) with the aid of a plate forming machine, wherein

   - individual layers of material (1, 2) to be combined to form the multilayer pipe (5) are laid one on top of the other, at least one of the layers of material (1) consisting of more than one laid-on element (1a 1b),

   - after that, a first connection (3a, 3b), respectively, is then created between the elements of the overlying layer of material (1a, 1b) and the adjacent layer of material (2) at the border along one of the longitudinal or transverse edges of the respective element of the overlying layer of material (1, 1a, 1b), or approximately along a line parallel thereto, but always along or parallel to the future longitudinal seam (8) of the pipe,

   - the multilayer material formed in this way is formed into the pipe (5) and, during the deformation, the edges (4a, 4b) of the elements (1a, 1b) of the overlying layer of material (1a, 1b) that are still freely displaceable with respect to one another can move freely toward one another in accordance with the extent to which deforming has progressed, on account of the different circumferential lengths of the inner pipe (1a, 1b) and the outer pipe (2),
   characterized in that

   - then, after deforming has progressed to a certain extent, these edges (4a, 4b) of the elements (1a, 1b) of the overlying layer of material (1a, 1b) that are moving toward one another butt against one another, and

   - then the multilayer pipe (5) is formed to completion with the aid of the plate forming machine, the edges (4a, 4b) of the elements (1a, 1b) of the overlying layer of material (1a, 1b) then no longer being able to move freely toward one another during this final forming, as a result of which the layer of material (1a, 1b) respectively acting as the inner pipe is pressed with a force fit into the layer of material (2) respectively acting as the outer pipe.
2. Process for producing a multilayer pipe (5) according to Claim 1, characterized in that the forming of the multilayer material into the pipe is designed in such a way that, when deforming has progressed to the extent that the edges (4a, 4b) of the elements (1a, 1b) of the overlying layer of material (1a, 1b) that were previously moving toward one another butt against one another, the pipe to be formed has already been made to curve at every point at which the inner layer and the outer layer lie one on top of the other.
3. Process for producing a multilayer pipe (5) according to Claim 1 or 2, characterized in that, in the finished multilayer pipe (5), the layer of material (1, 1a, 1b) acting as the inner pipe forms a pitch circle in cross section.
4. Process for producing a multilayer pipe (5) according to one of Claims 1 to 3, characterized in that the layer of material (1, 1a, 1b) acting as the inner pipe and forming a pitch circle in cross section of the finished multilayer pipe (5) forms a channel at the foot of the multilayer pipe.
5. Process for producing a multilayer pipe (5) according to one of Claims 1 to 4, characterized in that a connection, preferably welding, takes place between the edges (4a, 4b) of the elements of the overlying layer of material (1a, 1b) that butt against one another.
6. Process for producing a multilayer pipe (5) according to one of Claims 1 to 5, characterized in that the multilayer pipe (5) is closed by a welding (7) of the outer pipe (2) along the pipe seam (8) and a build-up welding (9) of the inner pipe (1, 1a, 1b).
7. Process for producing a multilayer pipe (5) according to one of Claims 1 to 6, characterized in that the layers of material (1, 1a, 1b, 2) are connected at the end faces of the pipe (5).
8. Process for producing a multilayer pipe (5) according to one of Claims 1 to 7, characterized in that a double-layer pipe is produced as the multilayer pipe (5).
9. Process for producing a multilayer pipe (5) according to one of Claims 1 to 8, characterized in that plates, preferably metal plates and particularly preferably steel plates, are used as the layer of material (1, 2) or elements (1a, 1b) of the layer of material (1).
10. Process for producing a multilayer pipe (5) according to one of Claims 1 to 9, characterized in that at least one of the connections (3a, 3b, 4a, 4b) of the layers of material (1, 2) is performed as welding.
11. Process for producing a multilayer pipe (5) according to one of Claims 1 to 10, characterized in that the process is designed as a continuous process in which the layers of material (1, 1a, 1b, 2) to be combined or elements (1a, 1b) thereof are respectively unwound from a wound-up strip and then continuously laid one on top of the other and continuously connected, preferably welded, the subsequent pipe forming process likewise taking place continuously, in that a forming line which forms an open-seam pipe (5) from the layers of material laid continuously one on top of the other serves as the plate forming machine.
12. Process for producing a multilayer pipe (5) according to one of Claims 1 to 10, characterized in that a bending roll is used as the plate forming machine.
13. Process for producing a multilayer pipe (5) according to one of Claims 1 to 10, characterized in that a UO(E) press/die arrangement (13, 14, 15) is used as the plate forming machine.
14. Process for producing a multilayer pipe (5) according to one of Claims 1 to 10, characterized in that a JCO press/die arrangement is used as the plate forming machine.

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