DE102012019315A1 - Process for the rapid production of a multilayer pipe - Google Patents

Abstract

Method for the rapid production of a multilayer pipe (5) with the aid of a sheet metal forming machine, where the multilayer pipe (5) has at least one first material layer (1) and one material layer (2) adjacent to the first material layer (1), the adjacent material layer (2) at least is slightly bent, the material layers (1, 2) to be combined to form the multilayer pipe (5) are placed one on top of the other, the first material layer (1) being positioned as an overlying material layer (1) on the adjacent material layer (2), a first connection (3a) is created between the overlying material layer (1) and the adjacent material layer (2) in that the overlying material layer (1) with the adjacent material layer (2) approximately along a first edge (4a) of the overlying material layer (1) or approximately is connected along a line parallel to this, a second connection (3b) between the overlying material layer (1) and the adjacent material layer (2) created that the overlying material layer (1) with the adjacent material layer (2) is connected approximately along a second edge (4b) of the overlying material layer (1) or approximately along a line parallel to it, and the multilayer material thus formed (1, 2) is formed with the help of the sheet metal forming machine to form the multilayer pipe (5), the material layer (1) lying on top and then functioning as an inner pipe between the two material layer connections (3a, 3b) in (partial) ) Circumferential direction is compressed and thus pressed into the respective adjacent material layer (2), which then acts as an outer tube.

Description

The present invention relates to a method for the rapid production of 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 (eg, stainless and acid-resistant steel) and a high-strength, pressure-resistant outer layer (eg Feinkornbaustahl). 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 pipelines 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 not very difficult to process 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 the inner and outer tube - preferably inner and outer plates 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 auch 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 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 comprehensive comprehensive the outer tube die) the inner tube is pressed under elastic expansion of the outer tube and 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 on the front sides.

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 - such as particularly high-strength steels - as they are particularly advantageous for abrasion-resistant piping inside the pipe, 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

• - Assembled single multilayer pipe material layers to be combined, and
• - The thus formed multilayer material formed by means of the bending roll to a multilayer pipe, wherein in the final phase of tube forming in the bending roll a respective acting as an inner tube material layer is non-positively pressed into a functioning respectively as an outer tube material layer.

With the help of this method multilayer pipes can be produced, which do not require rolling and / or blast-plated semi-finished products, but on the other hand are not subject to the restrictions that brings 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 the respective functioning as an outer tube material layer and is held in this way frictionally in each outer tube, without having to expand the multilayer tube and thus the above Expansion methods mentioned.

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.

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

• - Individual material layers to be combined for multi-layer pipe to be combined, wherein acting as a respective outer tube material layer forms a base plate which has approximately along its two longitudinal edges or approximately parallel to each one, preferably welded, stop edge and the resting material layer loose between these stop edges lie comes, and
• - The multi-layer material thus formed using the bending roller is formed into a multilayer pipe, wherein the respective functioning as an inner tube material layer clamped between the stop edges and in the final phase of tube forming in the bending roll, the respective functioning as an inner tube material layer thereby frictionally in the respective outer tube functioning 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. Again, the functioning as an inner tube material layer is pressed while the Rohrfomung in the bending roller frictionally in the respective acting as an outer tube material layer and so frictionally held in the respective outer tube and without that it requires a connection, such as a weld to be created. 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.

• – einzelne zum Mehrlagenrohr zu kombinierende Werkstofflagen aufeinandergelegt, wobei zumindest eine der Werkstofflagen aus mehr als einem aufgelegten Element besteht,
• – hiernach dann eine jeweils erste Verbindung zwischen den randseitigen Elementen der aufliegenden Werkstofflage und der benachbarten Werkstofflage geschaffen wird,
• – der so gebildete Mehrlagen-Werkstoff zum Rohr geformt wird und bei der Verformung die noch frei gegeneinander verschiebbaren Kanten der Elemente der aufliegenden Werkstofflage aufgrund der unterschiedlichen Umfangslängen von Innenrohr und Außenrohr sich entsprechend dem Verformungsfortschritt frei aufeinander zu bewegen,
• – dann diese sich aufeinander zu bewegenden Kanten der Elemente der aufliegenden Werkstofflage nach einem bestimmten Verformungsfortschritt aneinander stoßen, und
• – sodann das Mehrlagenrohr mit Hilfe der Blechumformmaschine zu Ende geformt wird, wobei sich nun während dieser Endformung die Kanten der Elemente der aufliegenden Werkstofflage nun nicht weiter frei aufeinander zu bewegen können, wodurch die jeweilige als Innenrohr fungierende Werkstofflage kraftschlüssig in die jeweilig als Außenrohr fungierende Werkstofflage gepreßt wird.

Meanwhile, however, an optimized process of WO 2010/145680 A1 known, which requires neither an interruption of the tube forming process for material layer connection nor a subsequent incorporation of material parts. Here are

• Individual layers of material to be combined with the multilayer tube stacked on one another, wherein at least one of the material layers consists of more than one applied element,
• - Thereafter, a respective first connection between the edge-side elements of the overlying material layer and the adjacent material layer is created,
• - The thus formed multilayer material is formed into a tube and in the deformation, the freely mutually displaceable edges of the elements of the overlying material layer due to the different circumferential lengths of the inner tube and outer tube to move freely according to the deformation progress,
• - Then these mutually abutting edges of the elements of the overlying material layer abut each other after a certain deformation progress, and
• - Then the multi-layer pipe is formed with the help of Blechumformmaschine to the end, now now can not move freely towards each other during this Endformung the edges of the elements of the overlying material layer, whereby the respective functioning as an inner tube material layer frictionally in the respective functioning as an outer tube material layer is pressed.

In this method according to the prior art, 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, first, d. H. before the tube forming process, the edge laterally connected to the outer layer forming material layer, that is usually welded to this, are. During the tube forming process, so z. B. in the bending roll, then move the free ends of these elements due to the different bending radii (or circumferential lengths, which means the same thing) of inner and outer tube to each other and eventually encounter each other. 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. Thus, an interruption of the molding process - for example, for further welding of the material layers - to form a full-surface inner layer of material from the material provided inside the tube no longer required.

However, this approach has the disadvantage that here a downstream processing step, namely for welding the then located inside the pipe abutting edge is required. Also arises after this process so an additional third weld - namely at the abutting edge - inside the tube, which is an additional source of error.

It is therefore - starting from the WO 2010/145680 A1 - Object of the present invention to provide a method for producing multilayer pipes, in which an additional weld in the tube interior of the multilayer pipe is avoided, however, the production technical advantages of the method according to the WO 2010/145680 A1 remain preserved, so neither an interruption of the tube forming process for material layer connection still a subsequent incorporation of material parts of the parts is required.

• – die benachbarte Werkstofflage zumindest leicht gebogen wird, – (wobei hier unter ,gebogen' sowohl eine elastische, wie auch eine plastische Verformung zu verstehen ist) –,
• – die zum Mehrlagenrohr zu kombinierenden Werkstofflagen aufeinandergelegt werden, wobei die erste Werkstofflage als aufliegende Werkstofflage auf der benachbarten Werkstofflage positioniert wird,
• – eine erste Verbindung zwischen der – nach der Rohrformung als Innenrohr fungierenden – aufliegenden Werkstofflage und der – nach der Rohrformung als Außenrohr fungierenden – benachbarten Werkstofflage dadurch geschaffen wird, daß die aufliegende Werkstofflage mit der benachbarten Werkstofflage – vorzugsweise in etwa – entlang einer ersten Kante der aufliegenden Werkstofflage oder – vorzugsweise in etwa – entlang einer Linie parallel hierzu verbunden wird,
• – eine zweite Verbindung zwischen der aufliegenden Werkstofflage und der benachbarten Werkstofflage dadurch geschaffen wird, daß die aufliegende Werkstofflage mit der benachbarten Werkstofflage – vorzugsweise in etwa – entlang einer zweiten Kante der aufliegenden Werkstofflage oder – vorzugsweise in etwa – entlang einer Linie parallel hierzu verbunden wird, und
• – der so gebildete Mehrlagen-Werkstoff mit Hilfe der Blechumformmaschine zum Mehrlagenrohr geformt wird, wobei während dieser Formung ab einem gewissen Verformungsgrad die jeweilige aufliegende und sodann als Innenrohr fungierende Werkstofflage zwischen den beiden Werkstofflagenverbindungen in (Teil-)Kreisumfangsrichtung gestaucht und somit in die jeweilige benachbarte und sodann als Außenrohr fungierende Werkstofflage gepreßt wird.

This object is achieved by a method for rapid production of a multilayer pipe using a Blechumformmachine in which the multilayer pipe has at least a first material layer and a material layer adjacent to the first material layer, wherein

• - the adjacent material layer is bent at least slightly, - (in which 'bent' is meant both an elastic and a plastic deformation) -,
• The layers of material to be combined with the multilayer tube are stacked on one another, wherein the first material layer is positioned as a resting material layer on the adjacent material layer,
• A first connection between the material layer acting as inner tube after tube forming and the adjacent material layer after tube forming as outer tube is provided in that the resting material layer with the adjacent material layer preferably approximately along a first edge of the resting material layer or - preferably approximately - along a line parallel thereto,
• - A second connection between the overlying material layer and the adjacent material layer is created in that the overlying material layer with the adjacent material layer - preferably approximately - along a second edge of the overlying material layer or - preferably approximately - along a line parallel thereto, and
• - The thus formed multilayer material is formed by means of sheet metal forming machine for multilayer pipe, wherein during this shaping from a certain degree of deformation, the respective resting and then acting as an inner tube material layer between the two material layer compounds in the (partial) circumferential direction and thus compressed in the respective adjacent and then acting as an outer tube material layer is pressed.

It should be emphasized that the aforementioned method steps by the order of their listing in the above text by no means require the same order in the execution of the method according to the invention. In the execution of the method - apart from technical necessities in the sequence, such as the last-mentioned process step of tube forming by means of sheet metal forming machine, which indeed requires the previous formation (production) of the multilayer material - it does not necessarily on this order. For example, the two material layer connections (preferably approximately) can be created simultaneously instead of successively. It is also possible to first make one of the connections between the material layers and then only make the bend, in order then to create the second connection between the material layers.

The bending of the adjacent - preferably below - and after the (multilayer) pipe forming the outer layer of the multilayer pipe forming material layer brings their edges - seen in the pipe cross-section closer together. In the method according to the present invention, therefore, the interruption of the tube forming process in the sheet metal forming machine and an additional weld in the tube interior is avoided because here neither a break in the forming process in the sheet metal forming machine for connecting the material layers nor to form a full-surface material inner layer of the space provided here Material in the tube interior and no further (third) weld is required because the material inner layer can be made in one piece and on the other a bending of the adjacent material layer, so as a 'preloading' of the material takes place, what the connection of the two material layers together already allowed the (further) tube forming process in the sheet metal forming machine. The bonding of the material layers can thus happen before the actual tube forming process in the sheet metal forming machine (tube forming machine) and therefore does not interfere with this process further.

Any bending of the adjacent material layer along (about one or both) of its edges is preferably already done in accordance with the present invention to the final radius of the multilayer tube to be manufactured, as this avoids subsequent machining often associated with manufacturing problems such as edge squeezing. Such bending on the end radius can be about preferably with a bending press for metal sheets, as shown in the WO 2010/118759 A2 is known.

In a preferred embodiment of the method for the rapid production of a multilayer pipe by means of a sheet metal forming machine according to the present invention
single to multilayer pipe to be combined material layers stacked, and it is
then a first connection between the overlying material layer and the adjacent material layer created by the fact that the overlying material layer is connected to the adjacent material layer approximately along the first edge of the overlying material layer or approximately along a line parallel thereto,
whereupon the multilayer material thus formed - and thus also the adjacent material layer - is at least slightly bent in the region in which the material layers are connected approximately along the edge or along a line approximately parallel thereto through the first connection (for example FIG Term of bending as plastic or elastic deformation see above, there to the adjacent material layer),
the second still free edge of the overlying material layer is positioned relative to the adjacent material layer in the direction of a still free edge of the adjacent Wstofstofflage, and
Then the second connection between the overlying material layer and the adjacent material layer is created by that
the resting material layer is connected to the adjacent material layer approximately along the second, until then free edge of the overlying material layer or approximately along a line parallel thereto, and
the thus formed multilayer material is formed by means of the sheet metal forming machine for multilayer pipe, wherein
During this shaping from a certain degree of deformation, the respective resting and then functioning as an inner tube material layer between the two material layer compounds in (part) circumferential direction compressed and thus pressed into the respective adjacent and then acting as an outer tube material layer.

B_i

als der im Rohrquerschnitt betrachteten (Teil-)Kreisumfangslänge (Breite vor Rohrformung) der jeweilig als Innenrohr fungierenden Werkstofflage zwischen den beiden Verbindungen zwischen den Werkstofflagen etwa in mm angegeben,

L_nfa

der im Rohrquerschnitt gesehenen Kreisumfangslänge (Breite vor Rohrformung) der jeweilig als Außenrohr fungierenden Werkstofflage etwa in mm angegeben,

SA

der Wanddicke der jeweilig als Außenrohr fungierenden Werkstofflage etwa in mm angegeben,

SI

als der Wanddicke des jeweilig als Innenrohr fungierenden Werkstofflage etwa in mm angegeben, und

d₁

als dem Abstand der ersten Verbindung entlang der ersten Kante der aufliegenden Werkstofflage oder entlang einer Linie parallel hierzu von der entsprechenden ersten Kante der benachbarten Werkstofflage zum Zeitpunkt der Schaffung der ersten Verbindung zwischen den Werkstofflagen etwa in mm angegeben, und

d₂

als dem Abstand der zweiten Verbindung entlang der zweiten Kante der aufliegenden Werkstofflage oder entlang einer Linie parallel hierzu von der entsprechenden Kante der benachbarten Werkstofflage zum Zeitpunkt der Schaffung der zweiten Verbindung zwischen den Werkstofflagen etwa in mm angegeben.

In the above-described embodiment of the method according to the present invention, therefore, once again the interruption of the tube forming process in the sheet metal forming machine and also an additional weld in the tube interior is avoided, since neither an interruption of the molding process for the connection of the material layers, nor the formation of a full-surface material inner layer of the material provided inside the pipe inside and no further (third) weld is required because this by the 'biasing' of the multilayer material by means of the first one-sided bonding of the layers, the elastic or plastic bending in this area, the 'moving over' , Preferably, 'pulling over' towards the other end and finally the fixing of this 'bias' at this other end by local re-connecting eliminated. This embodiment of the production according to the invention described above is advantageous because it does not require any initial (initial) deformation - be it plastic or elastic - of the adjacent material layer. Rather, this bending is achieved only in the course of the execution of the manufacturing method according to the invention, namely by the positioning, preferably, 'pulling over' the overlying material layer simultaneously with this step of the method. Preferably, the circumference length (width) considered in the pipe cross-section of the material layer B _i acting between each of the two connections of the material layers as the inner pipe is chosen such that B _i > L _nfa - π (SA + SI) - (d ₁ + d ₂ ) With

B _i

as the (partial) circumference length considered in the tube cross-section (width before tube forming) of the respective material layer acting as inner tube between the two connections between the material layers is given in mm,

L _nfa

the circumference length seen in the pipe cross-section (width before pipe forming) of the material layer acting in each case as the outer pipe is given approximately in mm,

SA

the wall thickness of the respective material layer acting as outer tube is given in mm,

SI

indicated as the wall thickness of the material layer acting respectively as an inner tube in approximately mm, and

d ₁

as the distance of the first connection along the first edge of the overlying material layer or along a line parallel thereto from the corresponding first edge of the adjacent material layer at the time of creating the first connection between the material layers approximately in mm, and

d ₂

as the distance of the second connection along the second edge of the overlying material layer or along a line parallel thereto from the corresponding edge of the adjacent material layer at the time of creation of the second connection between the material layers approximately in mm.

The latter condition is equivalent to the fact that in the tube cross-section considered (partial) circumference of the later acting as an inner tube material layers between the two material layer connections is greater than - also considered in the tube cross-section (partial) circumference length of an inner layer, which in the case of two (in a tube formed according to the present inventive method) stress-free (between the two material layer connections) would result in mutually lying material layers. This compared to the above conditions larger (partial) circumference length between the two material layer connections then leads to a compression of the inner layer in the circumferential direction and thus to a radial compression of the inner to the outer layer.

σ_I

als Streckgrenze (welche in der Regel in etwa der Stauchgrenze insbesondere bei gewalzten Metallen – entspricht) der aufliegenden Werkstofflage (Innenlage), also des (späteren) Innenrohres – etwa in N/mm²,

E

als Elastizitätsmodul (E-Modul) der aufliegenden Werkstofflage (Innenlage), also des (späteren) Innenrohres – etwa in N/mm².

According to those already in the WO 2006/066814 A1 mentioned geometric relationships 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 connections between the overlying material layer (ie the material layer, which later forms the inner layer [or the inner tube]) and the In order to explain the mode of action here, in particular the formation of the pressing force which presses the respective inner layer of material against the respective outer material layer, the following representation of the geometric relationships is used:
To find this - preferably starting from two layers, so an overlying material layer, which forms the inner layer, ie the later inner tube after tube forming, and an adjacent Werkofflage after the tube forming the outer layer, so the later outer tube, forms - in addition to the already introduced sizes, also the following sizes use:

σ _I

as yield strength (which usually corresponds approximately to the compression limit, in particular for rolled metals) of the overlying material layer (inner layer), ie of the (later) inner tube - approximately in N / mm ² ,

e

as modulus of elasticity (modulus of elasticity) of the overlying material layer (inner layer), ie of the (later) inner tube - approximately in N / mm ² .

The length of the neutral fiber - in a circular bent state - of the (later) outer tube - here called L _nfa - is: L _nfa = (DA-SA) · π, which corresponds to the average circumference length (considered in the tube cross-section) - here the (later) outer tube - (and thus also the width of the respective material layer acting as the outer tube). If you wanted to fit the inner tube without any compression in the outer tube, so the length of its neutral fiber (without compression of the inner _layer ) - here L _nfiOS called - due to the different bending radii L _nfiOS = (DA - 2 · SA - SI) · π, which also corresponds to the mean circumferential length - here, however, the inner tube - amount.

Thus, if one uses a material _layer of width L _nfiOS as the inner _layer and a material _layer of width L _nfa as the outer layer, the inner layer can exactly fit into the outer layer during tube forming, which means that the respective longitudinal edges of the outer as well as the inner layer with the completion of the tube forming process - a geometrically ideal running tube forming process, ie the ideal formation of a circle (seen in the tube cross section) once assumed - at the same time abut each other. In this case, the inner tube would be pressed against the outer layer only by its built-up during the forming process spring-back force. A compression of the inner tube, which would open due to the built-up in the material pressure and its curvature outwards against the respective outer material layer out in an additional pressing force of the inner tube against the outer tube, however, would not take place.

However, such a method would just produce the method according to the invention. This raises the question of what - viewed in cross-section of the molded tube - (partial) circumference length (= width of the overlying material layer prior to forming) must have the inner layer, so that there is such a desired compression of the circumferential length of the inner layer of material (B _i ) or, what is the same, the width of the overlying material layer in the tube forming process.

According to the above explanations, the length over which the edges of the inner layer can move freely relative to those of the outer layer in the circumferential direction during tube forming: L _fv = L _nfa - _Lfios and thus L _fv = (DA - SA) · π - (DA - 2 · SA - SI) · π which is equivalent to L _fv = (SA + SI) · π is, which is clear that in principle always occurs a compression of each functioning as an inner tube material layer, if this is wider than the respective acting as an outer tube material layer minus the sum of the thickness of both adjacent material layers multiplied by the circle number π, so if for Width B _{i of} the material layer acting as inner tube applies B _i > L _nfa - π (SA + SI).

However, if the respective material layer functioning as an inner tube is compressed in width during tube forming-namely, by the two connections between the material layers created by the method according to the invention-the material layer acting as the inner tube is thereby also seen in the respective outer (ie from the inner space of the tube outwardly adjacent) material layer pressed. there can this pressing force to the yield strength (respectively compression limit, which is usually - especially in rolled metal sheets, approximately equal to the yield strength -) increase. In cases where there is no pronounced yield or compression limit, the so-called technical yield strength (also referred to as yield strength as the amount of stress of a plastic permanent elongation under a certain force) or technical compression limit may be used instead. On the other hand, above the zone of the so-called "Hook's straight line", ie in the area of plastic strain (eg in the so-called "Lüders curve"), this force can no longer be significantly increased (at least not proportionally). So if you want against this background on the above condition B _i > L _nfa - π (SA + SI), - which basically ensures compression at all - in addition to achieve maximum compression and thus a maximum compressive force, so the following should be considered:
The degree of compression of the inner material layer to reach the compression limit - here called ε _St - results according to Hooke's law:

Accordingly, in the case that the maximum pressing force of the inner material layer against the outer material layer is just to be achieved: B _{i -B i} · ε _St = L _{nfa -π} · (SA + SI).

wobei fit den maximal erreichbaren Stauchungsgrad

With regard to the width which results for the inner material layer in this case, then:

being fit the maximum achievable degree of compression

For practical purposes it should be considered that - if one wants to achieve the maximum pressing force of the inner as reliably as possible against the outer layer, in any case approximately - it must be ensured that the compression limit (≈ yield strength) is actually reached. This can be achieved by giving the maximum degree of compression, as it results from the material constants (σ _I , E), a certain - quite generous - surcharge - preferably up to 800% of the maximum degree of compression, more preferably of up to 600% or even up to 300% or up to 200% or even up to 100% of the maximum degree of compression - there.

Therefore, in the method according to the invention for the production of multilayer pipes for the width of the material layer strip acting as an inner tube, it is possible with regard to the achievement of the highest possible compressive force of the inner layer against the outer layer for practical purposes that

If the width of the inner layer is thus chosen to be greater than the term on the right of the equation, a possible compression allowance (see above) is taken into account, which reduces the production inaccuracies - for example in position and / or leadership of the material material tapes to each other - can compensate so that the desired maximum pressing force of the inner tube against the outer tube - at least approximately - is achieved safely.

Due to the compression allowance also an elastic expansion of the outer tube due to the radially acting compressive force of the inner tube to the outer tube and influences on the process by a pipe forming after the possible not exactly sheet-thick central layer of the neutral fiber of the respective material layer are collected.

However, the above statements assume that the compression of the inner layer is provided by the two connections between the material layers, wherein the - seen in the (later) pipe cross section - respective two corresponding edges of the adjacent material layers at the time of creation of the first and the second connection between the material layers in each case - preferably approximately - lie flush against each other and the respective connection also - preferably approximately - along the respective edge - preferably by a weld along the edge - takes place. However, if, for example, the second initially free edge of the overlying material layer (inner layer) is not pulled so far in the direction of the still free edge of the adjacent material layer (outer layer) that they lie flush against each other before - according to this embodiment of the present invention - the second compound is created, so is the resulting distance d ₂ between the second - along or parallel to the still free (second) edge of the overlying material layer running - material layer connection and the corresponding (second) edge of the adjacent material layer to be considered. The same applies correspondingly to the distance d _{1 of} the first material layer connection extending along or parallel to the other (first) edge of the resting material layer from the corresponding (first) edge of the adjacent material layer.

However, taking this into account, it follows L _fv = (SA + SI) · π - (d ₁ + d ₂ ) and thus: B _i > L _nfa - π (SA + SI) - (d ₁ + d ₂ ), as a condition for compression. If one wants to achieve a maximum compression, the result for B _{i is} accordingly:

Preferably, the method for producing a multi-layer pipe according to the present invention is characterized in that the first connection between the material layers is created by this - preferably approximately - along one of the longitudinal or transverse edges of the overlying material layer or - preferably approximately along a line parallel thereto but also along or parallel to the future pipe seam. The laid-up (n) material layer (s) may or may thus lie with its longitudinal edge parallel to the longitudinal edge of the adjacent (about underlying) material layer, but need not or must not. So it is also possible that they come to lie with their longitudinal edge transverse thereto or come. However, the connection with the adjacent (approximately below) material layer is preferably 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 cross-section in the finished multilayer tube, which can be achieved in that the elements of the overlying material layer, which later form the inner tube layer, cover only a part of the surface of the material layer, which later forms 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 slot tube, so after completion of - preferably essential - tube forming process, such as in the bending roll, then preferably in the inventive method for rapid production of a multilayer tube, the multilayer tube can be closed by welding the outer tube along the pipe seam. Also, this is preferably carried out a surfacing of the inner tube along the pipe seam. Preferably, the multilayer tubular body is thus completed.

Furthermore, 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, however, the invention is not limited thereto also three-, four- and more multi-layered tubes 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, ie z. Example, a three-roll bending machine, but also a press / die assembly, such as in the context of the known from the prior art UOE (U-shapes, O-forms, expanding) -Rohrformungsverfahrens (see for UOE method, for example: Hiersig, Heinz M., Encyclopedia Mechanical Engineering, Heidelberg 1997, p. 704f. to the keyword "longitudinal seam tube production") or else the so-called JCO tube deformation method is used 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 was deteriorated.

In the JCO process, the pipe 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'. Afterwards it is then - as in the case of the UOE process - bent into the, O'-shape.

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

1 - 6 a perspective outlined view of individual steps of the inventive method for rapid production of a multilayer pipe using a Blechumformmachine, these individual steps do not necessarily reflect all the same molding process of the same material layers, but rather schematically show characteristic steps or stations of the molding process and the individual material layers of step to step or from station to station may be quite different than they can be seen in the preceding or following steps or stations, so as to different variants of the inventive method based on a series of representations in the 1 to 6 to be able to show

7 a perspective cross-section through a finished multi-layer pipe with inner layer (also called inner tube, inner tube, inner plate, etc.) and outer layer (also called outer tube, outer tube, base plate, etc.),

8th a perspective cross section through a multilayer pipe after 7 with inner layer and outer layer in detail in the area of the (weld) joints in the vicinity of the longitudinal seam weld,

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

10 then forming the forming step of a 'U',

11 then the forming step, which forms an 'O', ie a slot tube, and

12 an exemplary stress-strain diagram for explaining how the desired maximum pressing force is achieved by compression of the inner layer in the scope.

1 shows a first and second step of an embodiment of the method according to the invention for the rapid production of a multilayer pipe by means of a Blechumformmachine in perspective view (the sheet metal forming machine is not seen here).

In a first step, individual material layers to be combined with the multilayer pipe, namely an overlying material layer, are produced 1 and an adjacent material layer 2 superposed.

In a second step then becomes a first connection 3a - Preferably a welded joint - between the overlying material layer 1 and the adjacent material layer 2 created by the fact that the resting material layer 1 with the adjacent material layer 2 - Preferably approximately - along a first edge 4a the resting material layer 1 connected - preferably welded - is. The first edge 4a the resting material layer 1 corresponding (first) edge 6a the adjacent material layer 2 is here from the first connection 3a of the two material layers to be seen 1 . 2 by the distance d ₁ - in view of the resting material layer 1 and its first edge 4a - offset to the outside. The first connection 3a the material layers 1 . 2 is thus also from the first edge 4a the resting material layer 1 corresponding (first) edge 6a the adjacent material layer 2 by the distance d ₁ - with regard to the adjacent (here below) material layer 2 and its first edge 6a - offset inwards.

2 then shows a third step of the method according to the 1 to 6 where the multilayer material formed by the preceding steps in the area in which the material layers 1 . 2 along the edge 4a through the first connection 3a are joined together, is bent, which is about by means of a bending roll, z. B. a three-roll bending machine or by means of a press, such as a press brake, but also by means of any other suitable machine or any other suitable tool (possibly also manually) can be done. Here are the first edge 4a the resting material layer 1 and the corresponding edge 6a the adjacent material layer 1 flush with each other. The in 1 mentioned distance d ₁ between the first connection 3a the material layers 1 and 2 and the edge 6a the adjacent material layer 2 here along the two adjacent edges 4a and 6a runs, is at the here to see material layers 1 . 2 therefore zero.

3 then shows a fourth step of the method according to the present invention according to the 1 to 6 , where here the still free edge 4b the resting material layer 1 relative to the adjacent material layer 2 in the direction 10 their also free (second) edge 6b is moved. This is preferably done so that this edge 4b approximately by means of a gripping device (not visible here) is detected, for. B. by a pair of pliers, which is the resting material layer 1 by means of one or more jaws (not visible here) attacks and then - for example by means of the gripping device - in the direction 10 the also still free (second) edge 6b the adjacent material layer 2 is pulled. However, this can also be done by means of any other machine suitable for this purpose and / or a tool suitable for this purpose (possibly, for example, but also manually). In principle, it is also possible for the movement of the material layers provided in accordance with the invention in this way 1 . 2 and their respective still free (second) edges 4b . 6b also achieve each other by the fact that the material to be supported 1 - Preferably below - adjacent material layer 2 , towards the (second) edge 4b the resting material layer 1 is moved. Likewise, both edges can 4b . 6b be moved against each other. The decisive factor is that there is a relative movement of the still free (second) edge 4b the resting material layer 1 to the still free (second) edge 6b the adjacent material layer 2 comes that the distance between these two still free (respective second) edges 4b . 6b each other - preferably up to a distance of zero, so therefore no remaining distance more - reduced. Then, a second connection 3b between the material layers 1 . 2 done here along the (second) still free edge 4b the resting material layer 1 - Preferably as a welded joint, - as a weld - runs. The distance d ₂ between this (second) connection 3b the material layers together to the (second) edge 6b the neighboring (here below) Material layer is also marked here. The second edge 4b the resting material layer 1 corresponding (second) edge 6b the adjacent material layer 2 lies here of the second connection 3b of the two material layers to be seen 1 . 2 by the distance d ₂ - in view of the resting material layer 1 and its second edge 4b - offset to the outside. The second connection 3b the material layers 1 . 2 is thus also of the second edge 4b the resting material layer 1 corresponding (second) edge 6b the adjacent material layer 2 by the distance d ₂ - with regard to the adjacent (here below) material layer 2 and its second edge 6b - offset inwards.

4 shows, for the first, a fifth step of the method according to the 1 to 6 in which two material layers 1 . 2 can be seen after the previously free edge 4b the resting material layer 1 relative to the adjacent material layer 2 in the direction 10 their also previously free edge 6b moved - preferably pulled - was and in the, from this movement finally resulting position of the material layers 1 . 2 to each other a second connection 3b - Preferably a welded joint, such as a weld - between the overlying material layer 1 and the adjacent material layer 2 was created. A first connection 3a was already along the first edge 4a the resting material layer 1 been created. In the embodiment, which can be seen here, are also the respective corresponding edges 4a . 6a on the one hand and 4b and 6b on the other hand, both material layers 1 and 2 (approximately) flush with each other, namely in each case on the line along which each of the two material layer connections 3a on the one hand and 3b on the other hand. According to the embodiment, as can be seen here, while moving the previously free edge 4b the resting material layer 1 in the direction 10 the also previously free edge 6b the - lying down here - adjacent material layer 2 and the subsequent second compound 3b the two material layers 1 . 2 along the previously free edge 4b the resting material layer 1 already caused a curvature of the entire future tubular body.

To the other shows 4 but also the first step of another embodiment of the method according to the present invention, namely where the adjacent material layer 2 was bent, for example by means of bending press for metal sheets, as they are from the WO 2010/118759 A2 is known and which makes it possible in the area of the edges 6a and 6b the adjacent material layer 2 already reach the final radius of the multilayer pipe to be produced. The bend of the adjacent material layer 2 but can also be achieved by the fact that this situation 2 is pressed into an appropriately shaped die or even placed where it undergoes a bend due to the pressure or by its own weight.

The material layers to be combined with the multilayer pipe 1 . 2 were then stacked on top, with the first material layer 1 as a resting material layer 1 on the adjacent material layer 2 was positioned.

Also became a first connection 3a between the laying material layer 1 and the adjacent material layer 2 created by the fact that the laying material layer 1 with the adjacent material layer 2 approximately along a first edge 4a the resting material layer 1 was connected. A second connection 3b between the lying material layer 1 and the adjacent material layer 2 was also created, and approximately along a second edge 4b the resting material layer 1 , wherein these compounds both sequentially, but also - preferably in about - can be created simultaneously. A (approximately) simultaneous creation of both compounds is possible, for example, if the overlying material layer 1 immediately - for example by means of a suitable conveyor - in the correct position on the adjacent - then already bent - material layer 2 is positioned.

The thus formed multilayer material 1 . 2 can then with the help of Blechumformmaschine (not seen here) for multilayer pipe 5 be formed, during which molding from a certain degree of deformation, the respective resting and then acting as an inner tube material layer 1 between the two material layer connections 3a . 3b in - seen in the cross section of the (later) (multi-layer) tube - (part) circular circumferential direction and thus in the adjacent and then acting as an outer tube material layer 2 is pressed.

The 5 and 6 finally show the last step of a preferred embodiment of the method according to the present invention according to the 1 to 6 where the multilayer material formed by previous steps using the Blechumformmaschine (not visible here) to the pipe 5 (More precisely to the slotted tube), namely to the multi-layer tube (more precisely multi-layer slot tube) is formed, wherein the material layers during this molding 1 . 2 - due to the previous connections 3a . 3b with each other - (preferably from a certain deformation progress) between the two compounds 3a and 3b in - seen in the cross section of the (later) (multilayer) pipe - (part-) Circumferentially circumferential direction, whereby the respective functioning as an inner tube material layer 1 - Preferably non-positively - in each acting as an outer tube material layer 2 is pressed.

7 then shows a perspective cross section through a finished multilayer pipe 5 with inner layer (also called inner material layer, inner layer of material, inner tube, inner tube, inner plate or the like) 1 and outer layer (also called outer material layer, material outer layer, outer tube, outer tube, base plate or the like) 2 , where the multilayer pipe 5 preferably by a weld 7 of the outer tube 2 along a Rorhrnaht 8th has been closed. Preferably, a contract weld for closing the tube 9 of the inner tube 1 done, which can be seen here. Such a hardfacing 9 is not mandatory. The first (welding) connection 3a and the second (welding) connection 3b between the lying material layer 1 and the adjacent material layer 2 are also shown.

8th shows a perspective cross section through a multilayer pipe after 7 with inner layer 1 and outer layer 2 in detail view in the area of (welding) connections (such as welding seams) 3a . 3b and welds (such as welds or build-up welds) 7 and 9 ,

9 shows a situation of the inventive method, when the sheet metal forming is carried out approximately by means of a UO (E) -Pressen- / Gesenkanordnung. The later outer material layer 2 lies down here and the later inner layer 1 above. The upper layer 1 was with her - after welding the first connection 3a with the neighboring location 2 - still free edge 4b in the direction 10 the still free edge 6b the neighboring (here below) material layer 2 pulled until the distance between both edges 4b and 6b Zero became (the edges 4b and 6b that is, they hit one another directly) and in this position of the edges 4b and 6b to each other with the adjacent - down here - material layer 2 along the edge 4b welded at the edge, creating a second connection 3b between the material layers 1 . 2 originated. The pulling over of the initially free edge 4b the resting material layer 1 in the direction 10 the initially also free edge 6b the neighboring (here below) material layer 2 At the same time, it also has a bending (be it a plastic bending or an elastic bending) at the other end of the material layers 1 . 2 namely in the area of the first connection 3a caused, which again shows that the bending does not necessarily have to be performed as a first step.

10 then shows the forming step of a 'U' shaped by means of a press (not shown here), which has a correspondingly shaped punch 11 drives down where the material layers 1 and 2 In doing so, they are driven together into a mold (not to be seen here as well). Here, the acting as inner tube material layer 1 - Preferably from a certain deformation progress - (with appropriate width of the inner layer 1 ) between the two connections 3a . 3b the material layers 1 . 2 upset and (non-positively) in the functioning as an outer tube material layer 2 pressed.

11 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 12 . 13 drives against the tubular body to be formed, where the material layers 1 and 2 This in turn together to form a - seen in cross section - round. Here, too, the internal material layer 1 with appropriate width between the two material layer connections 3a and 3b compressed and there in the outer layer 2 pressed. As a result of the curvature, which also results in other sheet metal forming machines for tube forming or tube forming tools or tube forming methods, such as tube forming by means of a bending roll, such as a three-roll bending machine, the inner layer jumps 1 not from the outside situation 2 but lies down to the outer layer 2 at.

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 again two layers of material 1 and 2 , as formed in the invention modified UO (E) method. Again, the resting material layer 1 with the material layer forming the later outer layer 2 at least by two connections 3a . 3b connected and then a slot tube formed by the JCO method. Again, the desired effect according to the invention occurs in which (preferably from a certain deformation progress) a compression of the inner layer 1 - With appropriate width - between the two material layer connections 3a and 3b enters and so the inner layer 1 in the outer layer 2 is pressed.

In all cases, ie in particular in accordance with the invention modified UO (E) method, as well as in the invention modified JCO method, the compounds 3a and 3b the two material layers 1 and 2 by means of a weld, such as a weld.

12 shows an exemplary stress-strain diagram for explaining how the desired maximum pressing force is achieved by compression of the inner layer in the extent.

The aim of the present invention is to compress the inner layer material of the multilayer pipe so far that you get into the area S of the here seen stress-strain diagram, so as to achieve the maximum possible compression of the inner to the outer layer by the compression, which to ensure a firm fit of the inner tube in the outer tube.

If the respective material layer functioning as an inner tube in the tube forming in the width - such as by the first and second connection of the two material layers together with a corresponding sufficient width B _{i of} the inner layer - compressed, so the respectively functioning as an inner tube material layer is thereby also in the respective outer (So seen from the pipe interior to the outside adjacent) pressed material layer. This pressing force can be up to the yield strength σ _I (respectively compression limit, which is usually - especially in rolled metal sheets, approximately equal to the yield strength -) increase. In cases in which there is no pronounced yield or compression limit, the so-called technical yield strength (also referred to as yield strength as the amount of stress of a plastic permanent elongation under a certain force) or technical compression limit can be cited instead. Above the zone of the so-called 'Hook's straight line' - here in the figure, the range H -, that is approximately in the area of plastic strain (eg in the so-called 'Lüders curve') - in this case the area S - on the other hand This force does not increase significantly anymore (at least not proportionally).

The condition B _i > L _nfa - π (SA + SI), or the condition B _i > L _nfa - π (SA + SI) - (d ₁ + d ₂ ), if one considers the compression between the two material layer connections, which are at the distance of d ₁ or d ₂ to the respective edges of the adjacent material layer preferably inwardly (ie to the center of the adjacent material layer) out (If the connection along the respective edge of the overlying Material layer and this come to be flush with their respective edge of the adjacent material layer, the term d ₁ + d ₂ = 0!), First ensures a compression at all.

wobei E die Steigung der sogenannten Hook'schen Geraden im Bereich H ist, wenn es eine solche (ausgeprägte Hook'sche Gerade) für das Material gibt. Demnach gilt für den Fall, daß die maximale Preßkraft der Innenwerkstofflage gegen die Außenwerkstofflage gerade eben erreicht werden soll: B_i – B_i·ε_St = L_nfa – π·(SA + SI). If you also want to achieve maximum compression and thus a maximum compressive force (as a result of this compression), the following should be considered:
The degree of compression of the inner material layer to reach the compression limit - here ε _St - results according to Hooke's law:

where E is the slope of the so-called Hook's line in the area H, if there is such a (pronounced Hook's line) for the material. Accordingly, in the case that the maximum pressing force of the inner material layer against the outer material layer is just to be achieved: B _{i -B i} · ε _St = L _{nfa -π} · (SA + SI).

wobei für den maximal erreichbaren Stauchungsgrad

With regard to the width which results for the band of the inner material layer in this case, then:

where for the maximum achievable degree of compression

For practical purposes it should be considered that - if one wants to achieve the maximum pressing force of the inner against the outer layer as reliably as possible, in any case approximately, it must be ensured that the compression limit σ _I (≈ yield strength) is actually reached. This can be achieved by adding to the maximum degree of compression, as it results from the material constants σ _I and E, still a certain surcharge - preferably up to 800% of the maximum compression ratio, more preferably up to 600% or up to 300% or up to 200% or up to 100% of the maximum degree of compression ε _St - gives.

Therefore, in the method according to the invention for the production of multilayer pipes for the width of the material layer strip acting as an inner tube, it is possible with regard to the achievement of the highest possible compressive force of the inner layer against the outer layer for practical purposes that

Due to the fact that the width of the inner layer is chosen to be greater than the right of the equation term, a compression allowance is taken into account, which can compensate for the manufacturing inaccuracies - such as position and / or leadership of the material material tapes - so that the desired maximum pressing force of Inner tube against the outer tube - at least in about - safely achieved. In this way, it is safe for the material of the inner layer thus reaches the area S, where the desired maximum pressing force of the inner tube against the outer tube is guaranteed, as seen from here - in approximately - always the maximum return spring force of the inner tube acts. Compression surcharges of 100%, 200% and 300% are included in the diagram for illustration purposes. Likewise, the Rückfederweg R from 300% compression surcharge starting is entered as an example in the diagram. It follows that the resulting from the compression of the inner layer pressing force in the area S no longer, at least not significantly, increases.

so man eine maximale Preßkraft der Innen- gegen die Außenlage im Bereich zwischen den beiden Werkstofflagenverbindungen erreichen will. Für den Stauchungszuschlag gilt auch hier das bereits vorstehend Gesagte.Taking into account the pressing of the material layers against each other in the area between the two material layer connections, which are at a distance from d ₁ or d ₂ to the respective edges of the adjacent material layer preferably inwards (ie to the center of the adjacent material layer) out, it follows for B _i as the width of the inner layer between the two material layer connections:

so you want to achieve a maximum pressing force of the inner against the outer layer in the area between the two material layer connections. For the compression surcharge applies here also the above.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2006/066814 A1 [0010, 0014, 0015, 0027]
• WO 2010/145680 A1 [0016, 0019, 0019]
• WO 2010/118759 A2 [0023, 0066]

Cited non-patent literature

• Hiersig, Heinz M., Encyclopedia Mechanical Engineering, Heidelberg 1997, p. 704f. [0050]

Claims (20)

Method for the rapid production of a multilayer pipe ( 5 ) by means of a Blechumformmachine, characterized in that the multilayer pipe ( 5 ) at least a first material layer ( 1 ) and one to the first material layer ( 1 ) adjacent material layer ( 2 ), wherein - not necessarily in the following order - - the adjacent material layer ( 2 ) is at least slightly bent, - the multi-layer pipe ( 5 ) to be combined material layers ( 1 . 2 ), wherein the first material layer ( 1 ) as a resting material layer ( 1 ) on the adjacent material layer ( 2 ), - a first connection ( 3a ) between the lying material layer ( 1 ) and the adjacent material layer ( 2 ) is created by the fact that the resting material layer ( 1 ) with the adjacent material layer ( 2 ) approximately along a first edge ( 4a ) of the overlying material layer ( 1 ) or is connected approximately along a line parallel thereto, - a second connection ( 3b ) between the lying material layer ( 1 ) and the adjacent material layer ( 2 ) is created by the fact that the resting material layer ( 1 ) with the adjacent material layer ( 2 ) approximately along a second edge ( 4b ) of the overlying material layer ( 1 ) or approximately parallel thereto along a line, and - the multilayer material thus formed ( 1 . 2 ) with the help of Blechumformmaschine to multilayer pipe ( 5 ) is formed, wherein during this shaping from a certain degree of deformation, the respective resting and then acting as an inner tube material layer ( 1 ) between the two material layer connections ( 3a . 3b ) in the (partial) circumferential direction and thus in the respective adjacent and then acting as an outer tube material layer ( 2 ) is pressed. Method for the rapid production of a multilayer pipe ( 5 ) according to claim 1, characterized in that the bending of the adjacent material layer ( 2 ) along at least one of its edges already on the end radius of the multilayer tube to be produced ( 5 ) he follows. Method for the rapid production of a multilayer pipe ( 5 ) according to claim 1 or 2, characterized in that - to the multilayer pipe ( 5 ) to be combined material layers ( 1 . 2 ) - then a first connection ( 3a ) between the lying material layer ( 1 ) and the adjacent material layer ( 2 ) is created by the fact that the resting material layer ( 1 ) with the adjacent material layer ( 2 ) approximately along the first edge ( 4a ) of the overlying material layer ( 1 ) or approximately parallel thereto along a line, - whereupon the multilayer material thus formed in the region in which the material layers ( 1 . 2 ) approximately along the edge ( 4a ) or along a line approximately parallel thereto through the first compound ( 3a ) are interconnected, at least slightly bent, and - the second still free edge ( 4b ) of the overlying material layer ( 1 ) relative to the adjacent material layer ( 2 ) in the direction of a still free edge ( 6b ) of the adjacent Wstofstofflage ( 2 ) - then the second connection ( 3b ) between the lying material layer ( 1 ) and the adjacent material layer ( 2 ) is created by the fact that the resting material layer ( 1 ) with the adjacent material layer ( 2 ) approximately along the second until then free edge ( 4b ) of the overlying material layer ( 1 ) or approximately parallel thereto along a line, and - the multilayer material thus formed by means of the sheet metal forming machine for multilayer pipe ( 5 ) is formed, wherein during this shaping from a certain degree of deformation, the respective resting and then acting as an inner tube material layer ( 1 ) between the two material layer connections ( 3a . 3b ) in the (partial) circumferential direction and thus in the respective adjacent and then acting as an outer tube material layer ( 2 ) is pressed. Method for the rapid production of a multilayer pipe ( 5 ) according to claim 1, 2 or 3, characterized in that the width before tube forming B ;, the respective material layer acting as inner tube ( 1 ) in the region between the two compounds ( 3a and 3b ) of the material layers ( 1 . 2 ) is selected with each other so that B _i > L _nfa -π (SA + SI) - (d ₁ + d ₂ ) with B _i as the (partial) circumference length considered in the tube cross-section (= width before tube forming) of the respective material layer acting as inner tube ( 1 ) in the region between the two compounds ( 3a . 3b ) between the material layers ( 1 . 2 ) preferably in mm, L _nfa as seen in the tube cross-section circumference length (= width before tube forming) of each acting as an outer tube material layer ( 2 ), preferably in mm, SA as the wall thickness of the respective material layer acting as outer tube ( 2 ), preferably in mm, SI as the wall thickness of the respective material layer acting as an inner tube ( 1 ) preferably in mm, and d ₁ as the distance of the first compound ( 3a ) along the first edge ( 4a ) of the overlying material layer ( 1 ) or along a line parallel thereto from the corresponding first edge ( 6a ) of the adjacent material layer ( 2 ) at the time of the creation of the first link ( 3a ) between the material layers ( 1 . 2 ) preferably in mm, and d ₂ as the distance of the second compound ( 3b ) along the second edge ( 4b ) of the overlying material layer ( 1 ) or along a line parallel thereto from the corresponding second edge ( 6b ) of the adjacent material layer ( 2 ) at the time of the creation of the second link ( 3b ) between the material layers ( 1 . 2 ) preferably in mm. Method for the rapid production of a multilayer pipe ( 5 ) according to claim 1, 2, 3 or 4, characterized in that the width before tube forming B _i , the respective material layer acting as inner tube ( 1 ) in the region between the two compounds ( 3a and 3b ) of the material layers ( 1 . 2 ) is selected with each other so that

with B _i as the (partial) circumference length considered in the tube cross-section (= width before tube forming) of the respective material layer acting as inner tube ( 1 ) in the region between the two compounds ( 3a . 3b ) between the material layers ( 1 . 2 ) preferably in mm, L _nfa as seen in the tube cross-section circumference length (= width before tube forming) of each acting as an outer tube material layer ( 2 ), preferably in mm, SA as the wall thickness of the respective material layer acting as outer tube ( 2 ), preferably in mm, SI as the wall thickness of the respective material layer acting as inner tube ( 1 ) preferably in mm, σ _I as the yield strength or compression limit of the overlying material layer (inner layer) ( 1 ), ie of the (later) inner tube, preferably in N / mm ² , and with E as the modulus of elasticity (modulus of elasticity) of the resting material layer (inner layer) ( 1 ), ie of the (later) inner tube, preferably in N / mm ² , and d ₁ as the distance of the first connection ( 3a ) along the first edge ( 4a ) of the overlying material layer ( 1 ) or along a line parallel thereto from the corresponding first edge ( 6a ) of the adjacent material layer ( 2 ) at the time of the creation of the first link ( 3a ) between the material layers ( 1 . 2 ) preferably in mm, and d ₂ as the distance of the second compound ( 3b ) along the second edge ( 4b ) of the overlying material layer ( 1 ) or along a line parallel thereto from the corresponding second edge ( 6b ) of the adjacent material layer ( 2 ) at the time of the creation of the second link ( 3b ) between the material layers ( 1 . 2 ) preferably in mm. Method for the rapid production of a multilayer pipe ( 5 ) according to claim 2, 3, 4 or 5, characterized in that the relative movement of the second free edge ( 4b ) of the overlying material layer ( 1 ) to the adjacent material layer ( 2 ) in the direction of the still free edge ( 6b ) of the adjacent material layer ( 1 ) takes place in that the resting material layer ( 1 ) on its second, still free edge ( 4b ) in the direction of the still free edge ( 6b ) of the adjacent material layer ( 2 ) is pulled. Method for the rapid production of a multilayer pipe ( 5 ) according to one of claims 1 to 6, characterized in that the first compound ( 3a ) between the material layers ( 1 . 2 ) is created by the fact that the material layers ( 1 . 2 ) approximately along one of the longitudinal or transverse edges of the overlying Material layer ( 1 ) or parallel thereto and approximately along or parallel to the future longitudinal pipe seam ( 8th ). Method for the rapid production of a multilayer pipe ( 5 ) according to one of claims 1 to 7, characterized in that the second compound ( 3b ) between the material layers ( 1 . 2 ) is created by the fact that the material layers ( 1 . 2 ) approximately along one of the longitudinal or transverse edges of the overlying material layer ( 1 ) or parallel thereto and approximately along or parallel to the future longitudinal pipe seam ( 8th ). Method for the rapid production of a multilayer pipe ( 5 ) According to one of claims 1 to 8, characterized in that the inner tube acting as a material layer ( 1 ) in the case of greasy multilayer pipe ( 5 ) forms a partial circle in cross section. Method for the rapid production of a multilayer pipe ( 5 ) according to claim 9, characterized in that the acting as an inner tube and the greasy multilayer tube ( 5 ) in cross section a partial circle forming material layer ( 1 ) forms a groove at the foot of the multilayer pipe. Method for the rapid production of a multilayer pipe ( 5 ) according to one of Claims 1 to 10, characterized in that the first ( 3a ) or second compound ( 3b ) between the superimposed layers of material ( 1 . 2 ) a weld is made. Method for producing a multilayer pipe ( 5 ) according to one of claims 1 to 11, characterized in that the multilayer pipe ( 5 ) by a weld ( 7 ) of the outer tube ( 2 ) along the pipe seam ( 8th ) is closed. Method for producing a multilayer pipe ( 5 ) according to claim 12, characterized in that in addition a hardfacing ( 9 ) of the inner tube ( 1 ) along the pipe seam ( 8th ) done from the inside. Method for producing a multilayer pipe ( 5 ) according to one of claims 1 to 13, characterized in that the material layers ( 1 . 2 ) at the end faces of the tube ( 5 ) - preferably welded - are connected. Method for producing a multilayer pipe ( 5 ) according to one of claims 1 to 14, characterized in that as multilayer pipe ( 5 ) a double-layer tube is produced. Method for producing a multilayer pipe ( 5 ) according to one of claims 1 to 15, characterized in that sheets, preferably metal sheets and particularly preferably steel sheets, as material layer ( 1 . 2 ) be used. Method for producing a multilayer pipe ( 5 ) according to one of claims 1 to 16, characterized in that a bending roll is used as sheet metal forming machine. Method for producing a multilayer pipe ( 5 ) according to claim 17, characterized in that the bending roll is a three-roll bending machine. Method for producing a multilayer pipe ( 5 ) according to one of claims 1 to 16, characterized in that the sheet metal forming machine is a UO (E) press / die arrangement ( 13 . 14 . 15 ) Is used. Method for producing a multilayer pipe ( 5 ) according to one of claims 1 to 16, characterized in that a JCO press / die arrangement is used as the sheet metal forming machine.

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