EP2903757A1

EP2903757A1 - Method for the high-speed production of a multi-layered tube

Info

Publication number: EP2903757A1
Application number: EP13783468.5A
Authority: EP
Inventors: Bernd Berg
Original assignee: First Tube Intellectual Property Management Co of Luxembourg Sarl
Current assignee: First Tube Intellectual Property Management Co of Luxembourg Sarl
Priority date: 2012-10-02
Filing date: 2013-08-22
Publication date: 2015-08-12
Anticipated expiration: 2033-08-22
Also published as: EA201590383A1; CN104853859B; WO2014053108A1; DE112013004862A5; EP2903757B1; KR20150064733A; DE102012019315A1; SG11201502000VA; CN104853859A

Abstract

The invention relates to a method for the high-speed production of a multi-layered tube (5) with the aid of a sheet metal-forming machine, said multi-layered tube (5) comprising at least one first material layer (1) and another material layer (2) which adjoins said first material layer (1), the adjoining material layer (2) being at least slightly arched, and these being laid one upon the other to obtain combined material layers (1, 2) and form the multi-layered tube (5). The first material layer (1) is positioned, as an overlying material layer (1), on the adjoining material layer (2), and a first connection (3a) between said overlying material layer (1) and adjoining material layer (2) is made by virtue of the overlying material layer (1) being connected to the adjoining material layer (2) approximately along a first edge (4a) of the overlying material layer (1) or approximately along a line parallel thereto, and a second connection (3b) between said overlying material layer (1) and adjoining material layer (2) is produced by virtue of the overlying material layer (1) being connected to the adjoining material layer (2) approximately along a second edge (4b) of the overlying material layer (1) or approximately along a line parallel thereto. The multi-layered material (1, 2) which is formed in this manner is shaped, with the aid of the sheet metal-forming machine, to obtain the multi-layered tube (5) and, from a particular degree of deformation during this shaping process, the respective overlying material layer (1) which therefore functions as an inner tube is compressed between the two material layer connections (3a, 3b) in the (partial) circumferential direction, and therefore pressed into the respective adjoining material layer (2) which thus functions as an outer tube.

Description

Title: Method for the rapid production of a multilayer pipe

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 multi-layer 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 (e.g., fine grain structural 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 combinations of materials are possible in great variety. In principle, the combinability of materials is only limited by the respective processing techniques that are applicable.

In the construction of the tubular jacket is distinguished 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 plates and their welding to the sheet edges -.

CONFIRMATION COPY 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.

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 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 - such as particularly high-strength steels - as they are preferably used for abrasion-resistant pipelines. conditions in the interior of the tube are particularly advantageous, have high or even very high yield strengths and thus are not suitable for this production process.

Meanwhile, other methods from WO 2006/066814 AI are 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, individual to multilayer pipe to be combined Werks are stacked tofflagen, and formed so formed multilayer material using the bending roller to form a multilayer pipe, wherein in the final phase of pipe forming in the bending roll a respectively acting as an inner tube material layer frictionally in each acting as an outer tube material layer is pressed.

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 material layers, such as a weld seam, and thereafter the respective material layer acting as an inner tube during tube forming in the bending roll by one 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 production technical disadvantage that it is necessary here during the tube forming in the bending roll after a certain deformation progress to create a further connection between the factory tofflagen, which usually happens 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 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.

However, WO 2006/066814 A1 also teaches a method in which individual layers of material to be combined with the multilayer pipe are stacked, wherein a material layer acting as a respective outer tube forms a base plate, which in each case along one of its two longitudinal edges or approximately parallel thereto one, preferably welded , Stop edge and the resting material layer comes to rest loosely between these abutment edges, and the thus formed multilayer material is formed by means of the bending roll to form a multilayer tube, wherein the respective acting as an inner tube material sheet clamped between the stop edges and in the final phase of the Pipe forming in the bending roll the respective functioning as an inner tube material layer is thereby pressed non-positively in the respective acting as an outer tube material layer.

According to this embodiment of WO 2006/066814 A1, as the respective inner layer, it is therefore also possible to use those 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 during 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 simply by a build-up welding in this area, as a welded joint 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.

Meanwhile, however, an optimized method of WO 2010/145680 AI is known, which requires neither an interruption of the tube forming process for material layer connection nor a subsequent incorporation of material parts. Here, individual material layers to be combined for multi-layer pipe are stacked, wherein at least one of the material layers consists of more than one applied element, then then 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 for Pipe is formed and in the deformation of the still mutually displaceable edges of the elements of the overlying material layer due to the different circumferential lengths of inner tube and outer tube according to the deformation progress freely to move towards each other, then these mutually moving edges of the elements of the overlying material layer after a certain Forming progress abut each other, and then the multi-layer pipe is formed by means of the sheet metal forming machine to the end, which now forms during this final forming the edges of the elements of the resting plant Now tofflage can not move freely toward each other, whereby the respective functioning as an inner tube material layer is non-positively pressed into the respective acting as an outer tube material layer.

In this method according to the prior art, the interruption of the tube forming process in the Blechumformmaschine- thus avoided in the bending roll, that at least two elements that later form the inner layer, initially, ie before the tube forming process, the edge later with the outer layer forming material layer, that is usually welded to this, be. During the tube forming process So, for example, 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) 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, however, assuming a smoothly shaped edge, a, with increasing deformation progress strength, force exert on the material inner layer, with which this is pressed against the outer layer. Thus, an interruption of the shaping process, for example, for further welding of the material layer to form a full-surface inner layer of material from the material provided inside the tube is no longer necessary.

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 created by this method 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 AI - 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 advantages of the method according to WO 2010 / 145680 AI remain, so neither an interruption of the tube forming process for material layer connection nor a subsequent incorporation of material parts of the parts is required.

According to the invention, this object is achieved by a method for the rapid production of a multilayer pipe with the aid of a sheet metal forming machine in which the multilayer pipe has at least one first material layer and a material layer adjacent to the first material layer, with the adjacent material layer being bent at least slightly. (where "bent" is understood as meaning both elastic and plastic deformation) - which are stacked on the multilayer pipe to be combined material layers, wherein the first material layer is positioned as a resting material layer on the adjacent material layer, a first connection between the - after tube forming acting as an inner tube - resting material layer and - after tube forming acting as outer tube - adjacent material layer is created by the fact that the resting material layer with the adjacent material layer - preferably approximately - along a first edge of the lying 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 by the overlying material layer with the adjacent material layer - preferably approximately - along a second edge of the overlying material layer or - preferably in about - along a line parallel thereto is connected, and the thus formed multilayer material is formed by means of the sheet metal forming machine for multilayer pipe, during which molding from a certain degree of deformation ever That is, a continuous material layer which then acts as an inner tube is compressed in the (circumferential) circumferential direction between the two material-layer connections and thus pressed into the respective adjacent material layer which then acts as the outer tube.

It should be emphasized that the aforementioned method steps by the order of their enumeration 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 the sheet metal forming machine, which indeed requires the previous formation (production) of the multi-layer material - rather not necessarily in 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 bottom - and after the (multi-layer) 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 inside the pipe 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 biasing ^{£ 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 Blechumform- 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 preferably according to the present invention already on the end radius of the multilayer tube to be manufactured, as this avoids a subsequent, often with manufacturing problems such as edge pinching, connected processing. Such a bending on the end radius can be carried out approximately preferably with a bending press for metal sheets, as it is known from WO 2010/118759 A2.

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, individual material layers to be combined with the multilayer pipe are stacked on top of each other, and then a first connection between the overlying material layer and the adjacent material layer is created by the resting material layer with the adjacent material layer approximately along the first edge of the overlying material layer or approximately along a line parallel thereto, whereupon the thus formed multilayer material - and thus the adjacent material layer - in the area in which the material layers in about along the edge or along one Line are connected approximately parallel thereto by the first connection to each other, at least slightly bent (the concept 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 relative to the adjacent material layer in the direction a likewise free edge of the adjacent Wstofstofflage is positioned, and then the second connection between the overlying material layer and the adjacent material layer is created by the fact that the resting material layer with 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 Mehrlagen- material is formed by means of sheet metal forming machine for Mehrlagen- tube, during which molding from a certain degree of deformation, the respective resting and then as inne nrohr acting material layer between the two material layer compounds in (e-) circumferential direction compressed and thus pressed into the respective adjacent and then acting as an outer tube material layer.

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 here too there is no interruption of the molding process for joining the material layers, nor for the formation of a full-surface material inner layer of the dedicated material inside the tube and no further (third) weld is required because this by, biasing ^£ of the multilayer material by means of the first single-sided bonding of the layers, the elastic or plastic bending in this area, which, across moving ' , preferably, drag over ^£ finally deleted toward the other end and the fixing of this, ^£ bias at this other end by connecting thereat but times. 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 bend is 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 achieved simultaneously with this step of the method. Preferably, the circumferential circumference (width) of the tube cross-section - of the respective material layer Bi functioning as an inner tube between the two compounds of the material layers is selected such that with Bi as the (partial) circumference length (width before tube forming) in the tube cross-section of the respective material layer acting as inner tube between the two connections between the material layers, given in mm,

L _nfa the seen in the pipe cross-section circumference length (width before tube forming) of the respectively acting as an outer tube material layer in about mm,

SA the wall thickness of each acting as an outer tube material layer is given in mm,

SI is given as the wall thickness of the respective material layer acting as an inner tube approximately in mm, and dj as the distance of the first connection along the first edge of the overlying

Material layer or along a line parallel thereto indicated by the corresponding first edge of the adjacent material layer at the time of creation of the first connection between the material layers approximately in mm, and

C-2 is given as the distance of the second joint 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 joint between the material layers approximately in mm.

The latter condition is tantamount to the fact that the (partial) circumference length of the laterally acting as inner tube material layers between the two material layer connections is greater than the - also in the pipe cross section bedettete - (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) of mutually lying material layers would result. This (partial) circumference length between the two material layer connections, which is greater than the above ratios, then leads to a compression of the inner layer in the circumferential direction and thus to a radial compression of the inner layer into the outer layer.

According to the already mentioned in WO 2006/066814 AI 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, the later Inner layer [or the inner tube] forms) and the adjacent material layer (ie the material layer, which later forms the outer layer [or the outer tube]) To explain the operation here, in particular the emergence of the pressing force, the respective material inner layer against the respective outer material layer presses, serves the following representation of the geometric relationships:

For this purpose, preferably starting from two layers, that is to say an overlying material layer which forms the inner layer, ie the later inner tube, after the pipe forming, and an adjacent workpiece layer which forms the outer layer, that is the later outer tube, after the pipe forming - in addition to the already introduced sizes, and the following sizes use: σι as yield strength (which usually corresponds approximately to the compression limit, especially in rolled metals -) of the overlying material layer (inner layer), ie the (later) inner tube - in N / mm ² ,

E as modulus of elasticity (modulus of elasticity) of the applied 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 _n f _a - is:

L _NFA = (DA - SA). TE, 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 functioning as outer tube). Did you want 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 _n ßQg called - due to the different bending radii

L nfiOS = (DA - 2 - SA - SI) - 7t, which also corresponds to the mean circumferential length - in this case, however, of the inner tube.

If, therefore, a material layer the width -L ^ QJ as an inner layer and a material layer the width L _n j _a as the outer layer, then the inner layer can fit exactly in the outer position during the pipe forming, which means that the respective longitudinal edges of the exterior, as well as the inner layer with the completion of Rohrformungprozesses- 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. 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 - seen in the cross section of the molded tube - (e-) circular circumference length (= width of the overlying material layer before forming) must have the inner layer, so that there is such a desired compression of the circumferential length Werlötoffinnenlage (Bi) or, which is the same, the width of the overlying material layer in the tube forming process comes.

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: and thus = (DA - SA) ^ - (DA - 2 - SA - SI) ^ which is equivalent to

= (SA + SI) ^, which makes it 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 outer tube material layer minus the sum of the thickness of both adjacent material layers multiplied by the Circular number π, that is, if for the width Bi of acting as an inner tube material layer applies

B> L ^ - ^ 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. This pressing force can be up to the yield strength (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 may be used instead. Above the zone of the so-called ^'Hook' see straight ', ie, in the area of plastic strain (eg in the field of so-called Luders curve ^£), however, no more (no more, at least proportional) can be this force substantially increase. So if you want against this background on the above condition

B _; > L ^ - ^ 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 E _St - results according to Hooke's law:

Accordingly, applies in the event that the maximum pressing force of the inner material layer against the ßenwerkstofflage just to be achieved:

Bi - _Bj - B * = _Lnfa - 7i - (SA + SI).

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

L " _fa - * (SA + SI)

B _: =

L _nfa - rc (SA + SI) E where 0 <- <1 holds for the maximum achievable degree of compression.

e

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 (~ yield strength) is actually reached. This can be achieved by adding to the maximum degree of compression, as it results from the material constants (σι, E), a certain - quite generous - surcharge - preferably up to 800% of the maximum degree of compression, more preferably from to to 600% or even up to 300% or up to 200% or up to 100% of the maximum degree of compression - there.

Preferably, therefore, in the inventive method for the production of multi-layer pipes for the width of acting as an inner tube material layer strip in terms of the achievement of the highest possible compressive force of the inner against the outer layer for practical purposes are required, that:

L _nfa - 7i (SA + SI)

B. "^fa" - with O <<1.

e

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 is able to compensate for the production inaccuracies, for example in position and / or guidance of the material layer strips the desired maximum pressing force of the inner tube against the outer tube is achieved in any case approximately.

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 6. ^ see the second - along the 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 accordingly for the

Distance _{dj of} the first material layer connection running along or parallel to the other (first) edge of the overlying material layer from the corresponding (first) edge of the adjacent material layer. However, taking this into account, it follows

L ,, = (SA + Sl) - 7t - (d _{1 +} d ₂ )

and thus:

B _; > Ι ^ - π (8Α + 8ΐ) - (ά _{1 +} ά ₂ ), as a condition for compression. If one wants to achieve a maximum compression, the result for B _{j is} accordingly:

L _{nf a} - 7i (SA + SI) - (d. + D ₂ ). _ft σ,

B. > - ^ ⁱ '- ^ -, with 0 <- <1.

e

Preferably, the method for producing a multi-layer tube 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 along - 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 therefore 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 carried out 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. Also, the functioning as an inner tube material layer in the finished multilayer pipe in cross section form a circle, which can be achieved in that the elements of the overlying material layer, which later form the Rohririnenlage cover only a portion 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-layer tubes of the invention are hereby basically produced.

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

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, as in the context of known from the prior art UOE (U-shapes, O-forms, expanding) - Tube forming method (see the UOE method, for example: Hiersig, Heinz M., Encyclopedia Mechanical Engineering, Heidelberg 1997, p 704 f., For keyword, ingsnaht Großrohrherstellun ^c ) or also the so-called JCO-tube deformation method is used. 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 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'. After that, it is then - as in the case of the UOE method - bent into the, Ο 'form.

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

1 to 6 is a perspective view of individual steps of the method according to the invention for the rapid production of a multilayer pipe by means of a sheet metal forming machine, these individual steps not necessarily representing all the same forming process of the same material layers, but rather characteristic steps or stations in a schematic way of the molding process and the individual material layers from step to step or from station to station can be quite different than they can be seen in the preceding or following steps or stations, so as different variants of the method according to the invention with reference to a series of representations in the 1 to 6 show that

7 shows 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.),

8 shows a perspective cross-section through a multilayer pipe according to FIG. 7 with inner layer and outer layer in a detailed view in the region of the (welded) joints in the vicinity of the longitudinal seam weld, FIG. 9 shows 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 forms the forming step of a 'U',

Fig. 11 then the forming step, which forms a, Ο ', ie a slot pipe, and

Fig. 12 is 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 with the aid of a sheet metal forming machine in a perspective view (the sheet metal forming machine can not be seen here).

In a first step, individual material layers to be combined to form the multilayer pipe, namely an overlying material layer 1 and an adjacent material layer 2, are stacked on top of each other.

In a second step, a first connection 3a - preferably a welded joint - between the resting material layer 1 and the adjacent material layer 2 created by the fact that the overlying material layer 1 with the adjacent material layer 2 - preferably approximately - endang a first edge 4a of the resting Material layer 1 connected - preferably welded - is. The (first) edge 6a of the adjacent material layer 2 corresponding to the first edge 4a of the resting material layer 1 lies here from the first connection 3a of the two material layers 1, 2 to be seen by the distance _dj with respect to the resting material layer 1 and its first Edge 4a - offset to the outside. The first connection 3a of the material layers 1, 2 thus also lies from the first edge 4a of the overlying material layer 1 corresponding (first) edge 6a of the adjacent material layer 2 by the distance d _j - with regard to the adjacent (here below) material layer. 2 and its first edge 6a - offset inwards.

Fig. 2 then shows a third step of the method according to Figs. 1 to 6, where the multilayer material formed by the preceding steps in the area in which the material layers 1, 2 endang the edge 4a by the first compound 3a verbun together - are bent, which can be done about by means of a bending roll, for example 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). Here, the first edge 4 a of the overlying material layer 1 and the corresponding edge 6 a of the adjacent material layer 1 lie flush against one another. The distance mentioned in FIG. 1 between the first connection 3a of the material layers 1 and 2 and the edge 6a of the adjacent material layer 2, which here runs along the two mutually flush edges 4a and 6a, is in the material layers 1, 2 to be seen here rithin, so zero.

Fig. 3 then shows a fourth step of the method according to the present invention corresponding to Figs. 1 to 6, in which case the still free edge 4b of the overlying material layer 1 relative to the adjacent material layer 2 in the direction 10 whose also still free (second) edge 6b is moved. This is preferably done so that this edge 4b is detected by means of a gripping device (not seen here), e.g. by a pair of pliers which grips the resting material layer 1 by means of one or more clamping jaws (not seen here) and then - in the direction of 10 of the likewise free (second) edge 6b of the adjacent material layer 2 - for instance by means of the gripping device. However, this can also be done by means of any other suitable machine and / or a tool suitable for this purpose (if appropriate, but also manually). In principle, it is also possible to achieve the movement of the material layers 1, 2 and their respective still free (second) edges 4b, 6b which are provided according to the invention in such a way that the material layer 2 adjacent to the material layer 1, preferably below, adjoins the material layer 2 in the direction the (second) edge 4b of the resting material layer 1 is displaced. Likewise, both edges 4b, 6b can be moved against each other. It is crucial that there is a relative movement of the still free (second) edge 4b of the overlying material layer 1 to the still free (second) edge 6b of the adjacent material layer 2, the distance between these two still free (respective second) edges 4b, 6b to each other - preferably up to a distance of zero, rmthin so no remaining distance more - reduced. Then, a second connection 3b between the material layers 1, 2 take place here along the (second) still free edge 4b of the resting material layer 1 - preferably as

Welded joint, - as a weld - runs. The distance d2 between this (second) connection 3b of the material layers to each other to the (second) edge 6b of the adjacent (down here) Material layer is also marked here. The (second) edge 6b of the adjacent material layer 2 corresponding to the second edge 4b of the overlying material layer 1 lies here from the second connection 3b of the two material layers 1 to be seen,

2 offset by the distance cL _j - in view of the overlying material layer 1 and the second edge 4b - to the outside. The second connection 3b of the material layers 1, 2 is therefore also of the second edge 4b of the overlying material layer 1 corresponding (second)

Edge 6b of the adjacent material layer 2 offset by the distance C-2 - with respect to the adjacent (here below) material layer 2 and the second edge 6b - inward.

FIG. 4 shows, for the first, a fifth step of the method according to FIGS. 1 to 6, in which two material layers 1, 2 can be seen, after the previously free edge 4b of the overlying material layer 1 relative to the adjacent material layer 2 in direction 10 thereof 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 compound 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 had previously been created along the first edge 4a of the overlying material layer 1. In the embodiment which can be seen here, moreover, the respectively corresponding edges 4a, 6a on the one hand and 4b and 6b on the other hand lie flush (approximately) flush with each other on the material layers 1 and 2, namely on the line along which the two material layer connections also follow 3a on the one hand and 3b on the other. According to the embodiment, as can be seen here, thereby moving the previously free edge 4b of the overlying material layer 1 in the direction 10 of the previously still free edge 6b of - here below - adjacent material layer 2 and the subsequent second connection 3b the two material layers 1, 2 along the previously free edge 4b of the overlying material layer 1 already caused a curvature of the entire future tubular body.

On the other hand, however, FIG. 4 also shows the first step of another embodiment of the method according to the present invention, namely First, the adjacent material layer 2 has been bent, such as by means of bending press for metal sheets, as known from WO 2010/118759 A2 and which makes it possible to reach in the region of the edges 6a and 6b of the adjacent material layer 2 already the final radius of the multilayer pipe to be produced , However, the bending of the adjacent material layer 2 can also be achieved approximately in that this layer 2 is pressed into a correspondingly shaped die or even placed where it undergoes a bend due to the pressure or its own weight.

The material layers 1, 2 to be combined to form the multilayer pipe were then stacked on one another, the first material layer 1 being positioned as a resting material layer 1 on the adjacent material layer 2.

Also, a first connection 3a between the overlying material layer 1 and the adjacent material layer 2 was created by connecting the overlying material layer 1 to the adjacent material layer 2 approximately along a first edge 4a of the overlying material layer 1. A second connection 3b between the overlying material layer 1 and the adjacent material layer 2 has also been created and approximately along a second edge 4b of the overlying material layer 1, these compounds both sequentially, but also - preferably approximately - can be created simultaneously. A (approximately) simultaneous creation of both compounds is approximately possible if the resting 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 multilayer material 1, 2 formed in this way can then be formed into a multilayer pipe 5 by means of the sheet metal forming machine, during which shaping the respective resting material layer 1, which then acts as an inner pipe, between the two material layer connections 3a, is produced above a certain degree of deformation , 3b in - seen in the cross section of the (later) (multi-layer) pipe - (partial) circumferential direction and thus compressed in the adjacent and then acting as an outer tube material layer 2 is pressed.

Finally, FIGS. 5 and 6 show the final step of a preferred embodiment of the method according to the present invention corresponding to FIGS. 1 to 6, where the multilayer material formed by previous steps is removed by means of the sheet metal forming machine (not shown here) Pipe 5 (more precisely to the slotted pipe), namely the multilayer pipe (more precisely multi-layer slot pipe) is formed, wherein during this molding the material gene 1, 2 - due to the previously made connections 3a, 3b with each other - (preferably from a certain deformation progress) between the two compounds 3a and 3b in - seen in cross-section of the (later) (multilayer) tube - (part) circumferential direction be compressed, whereby the respective functioning as an inner tube material layer 1 - preferably non-positively - is pressed into each functioning as an outer tube material layer 2.

Fig. 7 then shows a perspective cross-section through a finished multilayer pipe 5 with inner layer (as well as inner material layer, material inner layer, inner tube, inner tube, inner plate or the like called) 1 and outer layer (as well as outer material layer, outer material layer, outer tube, outer tube, base plate or the like called) 2, wherein the multilayer pipe 5 was preferably closed by a weld 7 of the outer tube 2 along a Rorhrnaht 8. Preferably, a contract weld 9 of the inner tube 1 can be made to close the tube, which can be seen here. However, such build-up welding 9 is not mandatory. The first (welding) connection 3a and the second (welding) connection 3b between the resting material layer 1 and the adjacent material layer 2 are also shown.

8 shows a perspective cross-section through a multilayer pipe according to FIG. 7 with inner layer 1 and outer layer 2 in a detailed view in the area of the (welded) connections (such as welds) 3a, 3b and the welds (such as welds or build-up welds) 7 and 9.

Fig. 9 shows a situation of the method according to the invention when the sheet metal forming is carried out approximately by means of a UO (E) press / die arrangement. The later outer material layer 2 Hegt down here and the later inner layer 1 above. The upper layer 1 was with her - after welding the first compound 3a with the adjacent layer 2 - still free edge 4b in the direction 10 of the still free edge 6b of the adjacent (here below lying) material layer 2 pulled to the distance between both edges 4b and 6b was zero (the edges 4b and 6b thus abut one another directly) and in this position the edges 4b and 6b are welded to one another at the edges along the edge 4b adjacent to the adjacent material layer 2 below, whereby a second connection 3b between the material layers 1, 2 has emerged. The pulling over of the first still free edge 4b of the overlying material layer 1 in the direction 10 of the first also still free edge 6b of the adjacent Here (at the bottom here) material layer 2 has here at the same time a bending (be it a plastic bending, be it an elastic bending) at the other end of the material layers 1, 2, namely caused in the region of the first compound 3a, which again shows in that bending does not necessarily have to be carried out as a first method step.

Fig. 10 then shows the forming step of a, U 'shaped by means of a press (not shown here), which drives a correspondingly shaped punch 11 down where the material layers 1 and 2 together in a die (not here also not to be driven). Here, the functioning as an inner tube material layer 1 - preferably from a certain deformation progress - (with a corresponding width of the inner layer 1) between the two compounds 3a, 3b of the material layers 1, 2 compressed and (non-positively) pressed into the outer layer acting as material layer 2.

Fig. 11 then shows the forming step, which forms a, Ο ', ie a slot tube by means of a press (not shown here), the two formed as a half-round punch 12, 13 drives against the tubular body to be formed, where the material layers 1 and 2 hereby again together to form a - seen in cross section - round. Here, too, the inner material layer 1 is compressed with a corresponding width between the two material layer connections 3a and 3b and pressed there into the outer layer 2. As a result of the curvature, which also results in other sheet metal forming 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 1 does not jump from the outer layer 2, but hangs up 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 in turn two layers of material 1 and 2, as in the present invention modified UO (E) method are formed. Again, the overlying material layer 1 is connected to the later outer layer forming material layer 2 at least by two compounds 3a, 3b and then formed a slot tube 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 a corresponding width - between enters the two material layer connections 3a and 3b and so the inner layer 1 is pressed into the outer layer 2.

In all cases, that is to say in particular in the modified UO (E) method according to the invention, as well as in the JCO method modified according to the invention, the connections 3a and 3b of the two material layers 1 and 2 can be produced by means of a weld, for example a weld.

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

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 works as inner tube factory tofflage in the tube formation in the width - compressed by the first and second connection of the two material layers together with a correspondingly sufficient width B _{j of} the inner layer - thus, the respectively acting as an inner tube material layer is characterized in the respective outer (ie seen from the pipe interior to the outside adjacent) pressed material layer. This pressing force can be up to the yield strength σι (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 Hooke's straight '- here in the figure, the region H -, ie, in the area of plastic strain (eg in the field of so-called Luders curve ^<) - in this case, the area south - by contrast, can this power not significantly (at least not proportionally) increase.

The condition

B _; > - π (SA + SI), or the condition

B _; > L _nfa - 7u (SA + Sl) - (d _{1 +} d ₂ ), taking into account the compression between the two material layer joints, which are spaced inwardly from each other at the distance from d _j or d2 to the respective edges of the adjacent material layer (ie lie to the center of the adjacent material layer) (If the connection endang of the respective edge of the overlying material layer and come this also still flush with their respective edge of the adjacent material layer, the term d _j + d2 = 0!), initially ensures a compression at all.

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 est - 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 _s - B _j . it, = L _nfa - 7U (SA + SI)

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

L " _fa - * (SA + SI)

L _nfa - 7i (SA + SI) wherein for the maximum achievable degree of compression 0 <- <lgilt.

For practical purposes, it must be considered that if the maximum pressing force of the inner against the outer layer is to be achieved as reliably as possible, in any case approximately, it must be ensured that the compression limit σ 1 (yield strength) is actually reached. This can be achieved by adding to the maximum degree of compression, as it results from the material constants σι 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 sst - gives.

Therefore, in the method according to the invention for the production of multi-layer tubes for the width of the material layer strip acting as an inner tube, it is possible with regard to achieving the highest possible compressive force of the inner layer against the outer layer for practical purposes that the following applies:

L _NF - JI (SA + SI) σ.

B. > - i with 0 <-! - <1.

! _ ^ L ^E

e

Due to the fact that the width of the inner layer is chosen to be greater than the term on the right of the equation, a compression allowance is taken into account, which is the manufacturing inaccuracies

- For example, in position and / or management 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

- certainly in any case - is achieved safely. 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.

Taking into account, in turn, the compression of the material layers in the area between the two material layer connections, which are spaced apart from each other by d- _j or d2. The edges of the adjacent material layer preferably lie inwards (ie towards the center of the adjacent material layer), so for B _j the width of the inner layer between the two material layer connections is:

B. > -SS i '- ^ with 0 <- <1.

e

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.

Claims

Title: Process for the rapid production of a multi-layer pipe Patent claims

1. A method for quickly producing a multi-layer pipe (5) with the aid of a sheet metal forming machine, characterized in that the multi-layer pipe (5) has at least a first material layer (1) and a material layer (2) adjacent to the first material layer (1), whereby - not necessarily in the following order - the adjacent material layer (2) is at least slightly bent, the material layers (1, 2) to be combined to form the multi-layer tube (5) are placed on top of each other, with the first material layer (1) as a resting material layer (1) on the adjacent material layer (2), a first connection (3a) between the overlying material layer (1) and the adjacent material layer (2) is created in that the overlying material layer (1) is connected to the adjacent material layer (2) approximately along a first edge (4a) of the overlying material layer (1) or approximately along a line parallel thereto, a second connection (3b) between the overlying material layer (1) and the adjacent material layer (2) is created in that the overlying material layer (1) is connected to the adjacent material layer (2) approximately along a second edge (4b) of the lying material layer (1) or approximately along a line parallel thereto, and the multi-layer material (1, 2) formed in this way is formed into a multi-layer tube (5) with the help of the sheet metal forming machine, during this forming from a certain degree of deformation the respective material layer (1) lying on it and then functioning as an inner tube between the two material layer connections (3a, 3b) is compressed in the (partial) circumferential direction and thus pressed into the respective adjacent material layer (2) which then functions as an outer tube.

Method for the rapid production of a multi-layer 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 takes place to the final radius of the multi-layer pipe (5) to be produced.

Method for the rapid production of a multi-layer pipe (5) according to claim 1 or 2, characterized in that the material layers (1, 2) to be combined to form the multi-layer pipe (5) are placed on top of each other, then a first connection (3a) between the resting material layer (1) and the adjacent material layer (2) is created in that the overlying material layer (1) is connected to the adjacent material layer (2) approximately along the first edge (4a) of the overlying material layer (1) or approximately along a line parallel thereto , whereupon the multi-layer material formed in this way is at least slightly connected to one another in the area in which the material layers (1, 2) are connected to one another approximately along the edge (4a) or along a line approximately parallel thereto by the first connection (3a). is bent, and the second still free edge (4b) of the resting material layer (1) is positioned relative to the adjacent material layer (2) in the direction of a likewise still free edge (6b) of the adjacent material layer (2), then the second connection (3b) between the overlying material layer (1) and the adjacent material layer (2) is created in that the overlying material layer (1) is connected to the adjacent material layer (2) approximately along the second previously still free edge ( 4b) the overlying material layer (1) or approximately along a line parallel to it is connected, and the multi-layer material thus formed is formed into a multi-layer tube (5) using the sheet metal forming machine, during this shaping from a certain degree of deformation onwards the respective overlying and The material layer (1), which then functions as an inner tube, is compressed between the two material layer connections (3a, 3b) in the (partial) circumferential direction and is thus pressed into the respective adjacent material layer (2) which then functions as an outer tube.

4. A method for the rapid production of a multi-layer pipe (5) according to claim 1, 2 or 3, characterized in that the width before pipe forming Bi, of the material layer (1) acting as an inner pipe in the area between the two connections (3a and 3b). Material layers (1, 2) are selected together so that

B _; > L _nfa - ^SA + Sl)- (d _a + d ₂ ) _lst , with Bi as the (partial) circular circumference length (=width) considered in the pipe cross section

Pipe shaping) of the material layer (1) acting as an inner tube in the area between the two connections (3a, 3b) between the material layers (1, 2), preferably given in mm,

Lnfa as the circumferential length seen in the pipe cross section (= width before pipe forming) of the material layer (2) acting as the outer pipe, preferably given in mm,

SA is the wall thickness of the material layer (2) acting as the outer tube, preferably given in mm,

SI as the wall thickness of the material layer (1) acting as the inner tube, preferably given in mm, and 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 creating the first connection ( 3a) between the material layers (1, 2), preferably given in mm, and d2 as the distance of the second connection (3b) along the second edge (4b) of the resting 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 creating the second connection (3b) between the material layers (1, 2), preferably given in mm.

5. A method for the rapid production of a multi-layer pipe (5) according to claim 1, 2, 3 or 4, characterized in that the width before pipe forming Bi, of the material layer (1) functioning as an inner pipe in the area between the two connections (3a and 3b ) of the material layers (1, 2) is selected together so that

L _f - π (SA + SI) - (d, + d, ) . , . _Λ σ.

B. > ⁱ '— ^lJ -, with 0 < — ^l - < 1

E

with Bi as the (partial) circumference length (=width) considered in the pipe cross section

Lnfa as the circumferential length seen in the pipe cross section (=width before pipe forming) of the material layer (2) acting as the outer pipe, preferably given in mm,

SA is given as the wall thickness of the material layer (2) acting as an outer tube, preferably in mm,

SI is given as the wall thickness of the material layer (1) acting as the inner tube, preferably in mm, σι as the yield point or compression limit of the overlying material layer (inner layer) (1), i.e. the (later) inner tube, preferably given in N/mm ² , and with

E as the modulus of elasticity (modulus of elasticity) of the overlying material layer (inner layer) (1), i.e. the (later) inner tube, preferably in N/mm ² , and d _j 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 creating the first connection (3a) between the material layers (1, 2), preferably given in mm, and d2 as the distance of the second connection (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 creation of the second Connection (3b) between the material layers (1, 2) is preferably given in mm.

6. A method for the rapid production of a multi-layer pipe (5) according to claim 2, 3, 4 or 5, characterized in that the relative movement of the second still free edge (4b) of the resting material layer (1) to the adjacent material layer (2) in the direction of Also still free edge (6b) of the adjacent material layer (1) is done by pulling the resting material layer (1) on its second, still free edge (4b) in the direction of the also still free edge (6b) of the adjacent material layer (2). becomes.

7. A method for the rapid production of a multi-layer pipe (5) according to one of claims 1 to

6, characterized in that the first connection (3a) between the material layers (1, 2) is created in that the material layers (1, 2) are approximately along one of the longitudinal or transverse edges of the resting material layer (1) or parallel to it and are connected to one another approximately along or parallel to the future longitudinal pipe seam (8).

8. A method for the rapid production of a multi-layer pipe (5) according to one of claims 1 to

7, characterized in that the second connection (3b) between the material layers (1, 2) is created in that the material layers (1, 2) approximately along one of the longitudinal or Transverse edges of the overlying material layer (1) or parallel to it and approximately along or parallel to the future longitudinal pipe seam (8) are connected to one another.

9. A method for the rapid production of a multi-layer pipe (5) according to one of claims 1 to 8, characterized in that the material layer (1) functioning as an inner pipe forms a partial circle in cross section in the finished multi-layer pipe (5).

10. A method for the rapid production of a multi-layer pipe (5) according to claim 9, characterized in that the material layer (1) which acts as an inner pipe and forms a partial circle in cross section in the finished multi-layer pipe (5) forms a groove at the foot of the multi-layer pipe.

11. A method for the rapid production of a multi-layer pipe (5) according to one of claims 1 to 10, characterized in that welding takes place as the first (3a) or second connection (3b) between the material layers (1, 2) lying one on top of the other.

12. A method for producing a multi-layer pipe (5) according to one of claims 1 to 11, characterized in that the multi-layer pipe (5) is closed by welding (7) the outer pipe (2) along the pipe seam (8).

13. A method for producing a multi-layer pipe (5) according to claim 12, characterized in that a build-up welding (9) of the inner pipe (1) takes place along the pipe seam (8) from the inside.

14. A method for producing a multi-layer pipe (5) according to one of claims 1 to 13, characterized in that the material layers (1, 2) are connected - preferably welded - to the end faces of the pipe (5).

15. A method for producing a multi-layer pipe (5) according to one of claims 1 to 14, characterized in that a double-layer pipe is produced as the multi-layer pipe (5).

16. A method for producing a multi-layer pipe (5) according to one of claims 1 to 15, characterized in that sheets, preferably metal sheets and particularly preferably steel sheets, are used as the material layer (1, 2).

17. A method for producing a multi-layer pipe (5) according to one of claims 1 to 16, characterized in that a bending roller is used as the sheet metal forming machine.

18. A method for producing a multi-layer pipe (5) according to claim 17, characterized in that a three-roll bending machine serves as the bending roller.

19. A method for producing a multi-layer pipe (5) according to one of claims 1 to 16, characterized in that a UO (E) press / die arrangement (13, 14, 15) is used as the sheet metal forming machine.

20. A method for producing a multi-layer 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.