Device and method for manufacturing a double-walled pipe

Abstract

Device for producing a double-walled tube from a sheet (2) comprising: at least one first pair of profile rolls (4a, 4b, 5a, 5b) for producing a Z-profile with a middle leg having a length and two outer legs in the sheet (2), wherein a pair of profile rolls (4a, 4b, 5a, 5b) has an upper profile roll (4a, 5a) and an opposing lower profile roll (4b, 5b), and at least one bending upper roll (7a) and one bending lower roll (8b) for producing a circular bend in the sheet (2), wherein the bending upper roll (7a) and the bending lower roll (8b) are arranged to simultaneously produce a helix in the sheet (2), such that adjacent turns of the helix partially overlap, a device for connecting a first passage of the helix with an adjacent second passage of the helix wherein the middle leg of the Z-profile has a length such that the overlapping outer legs of the Z-profile are spaced apart from each other in the direction of the diameter of the helix when they are coiled into a helix and rounded.

Description

[0001] The invention relates to a method and a correspondingly configured apparatus for manufacturing a double-walled tube from a sheet metal part, preferably from a strip of sheet metal, wherein the sheet metal is first bent into a Z-profile and then bent round to the radius of the tube and into a helix. The pitch of the helix is ​​dimensioned such that one turn of the helix partially overlaps an adjacent turn. The invention further relates to such a double-walled metal tube itself.

[0002] The production of so-called wound or spiral tubes from a typically long and narrow continuous strip, for example, a long sheet of metal, is known. In this process, the continuous strip is typically wound around a shaping cylindrical core, so that the continuous strip is bent into a helix. The continuous strip can be wound butt-wound or overlapping and joined at the butt joint or overlap, so that the coiled sheet metal forms a tube.

[0003] Spiral or wound pipes have long been known from EP 0 201 729 A2. Thin-walled spiral pipes are used, for example, for conveying air in buildings. The spiral pipes used can be wound from a (continuous) metal strip or a plastic strip, which are welded at the joints or joined together by means of a seam.

[0004] Spiral seam pipes are known from DE 696 10 996 T2. These are obtained by joining adjacent sections of a sheet metal sheet together by means of a spiral seam. From JP 2000-271 639 A, a pipe is known whose outer wall has steps corresponding to the height of the wall thickness.

[0005] From WO 2007 / 048 498 A1, a method and a device for manufacturing a wound tube are known, in which one or more layers of helically wound strip material form the tube. In this method, a wound tube is manufactured from a strip-shaped material, wherein the winding is effected by at least one rotating winding element with which the wound tube is in direct or indirect engagement, and wherein the strip-shaped material is wound with an overlap for reasons of stability, and at least one of the possibly several layers is made of metal.

[0006] Thicker sheets are typically not formed by winding, but are bent using rollers or cylinders to achieve the desired bend and, if necessary, a helix with the required pitch. The bent sheets are then welded together to form a closed tube, either simply butting against each other at their abutting edges and being welded there, or overlapping and being joined at the edges of the overlap.

[0007] Such pipes, whose material web is wound / bent edge-to-edge, have the disadvantage that they only consist of a single layer of material and therefore have limited stability. Pipes with overlapping material webs, on the other hand, have at least the disadvantage that the inner wall of the pipe is not smooth.

[0008] Accordingly, the task is to provide a production process, a suitable device for carrying it out, and a correspondingly produced tube that has sufficient strength and at least partially avoids the aforementioned disadvantages.

[0009] This problem is solved by means of a device and a method according to the independent claims.

[0010] The invention is described in more detail below with reference to figures. The figures show: Fig. 1 a schematic representation of an arrangement of rollers for profiling and bending a sheet metal, Fig. 2a a schematic sectional view of a first pair of profile rollers of the device, Fig. 2b a schematic sectional view of a second pair of profile rollers of the device, Fig. 2c a schematic representation of a pair of bending rollers, Fig. 3 a perspective view of an arrangement of profile and bending rollers, Fig. 4a a schematic view of a helix of the Z-profiled and round-bent sheet metal, Fig. 4b a schematic view of a section through a bent and coiled Z-profiled sheet metal, Fig. 5. A flowchart of a process for manufacturing a pipe.

[0011] The invention relates to a device for producing a tube from a sheet of metal, wherein the device comprises an arrangement of rollers for profiling and bending the sheet. The sheet can be a long strip of metal, which is unwound from a coil and fed to the device and thus to the arrangement of rollers. The sheet strip is first profiled with at least one upper and one opposing profile roller, so that the sheet strip subsequently has a Z-profile along its length. The height of the Z-profile, i.e., the height of the middle leg of the Z, can correspond to the thickness of the sheet or be significantly greater. The angles between the legs of the Z can, in particular, be right angles. The lengths of the two outer legs of the Z-profile can, in particular, be equal.

[0012] The sheet metal can be, in particular, a steel sheet with a thickness of 5 mm, preferably with a thickness of at least 10 mm. In a preferred embodiment, the sheet metal strip can have a width of at least 1 meter, preferably 2 meters or more.

[0013] The Z-profile sheet metal strip is then bent into a curve, giving it the desired bend corresponding to the pipe's diameter and also creating the helix. The helix pitch, i.e., the thread height, can be designed such that the middle leg of the Z-profile of the profiled sheet metal strip rests against an edge of the profiled sheet, and the outer legs of the Z-profiled and bent sheet at least partially overlap. Finally, the profiled, bent, and helixed sheet can be welded or otherwise suitable joined at the joint between the sheet edge and the middle leg, resulting in a pipe that is at least partially double-layered.

[0014] The following section describes the device and the steps of the corresponding process in more detail. First, the steps for profiling the sheet metal are explained, followed by the steps for roll bending, whereby the Z-profiled sheet metal strip is simultaneously bent into a helix. The conveying direction of the sheet metal is indicated by the directional arrow 3 in the following figures.

[0015] Fig. Figure 1 shows a schematic arrangement of profile and bending rollers for profiling and round bending a sheet metal part 2. The sheet metal part 2 can, in particular, be a long strip of sheet metal, which is unwound from a coil and fed to a device 1 for producing the tube. The direction of movement of the sheet metal part is indicated by the arrow 3. In the diagram shown, the sheet metal part is first given its Z-profile by profile rollers. Subsequently, the sheet metal part is bent into a round shape and a helix according to the tube diameter by bending rollers.

[0016] The arrangement 1 of rollers can optionally include an upper and an opposing lower conveyor roller 6a, 6b for conveying the sheet metal 2 and / or for controlling the precise feeding of the sheet metal 2. In one embodiment, at least one of the conveyor rollers 6a, 6b is driven by a motor; preferably, both conveyor rollers 6a, 6b are driven. The conveyor rollers 6a, 6b are preferably arranged as the first pair of rollers in the conveying direction of the sheet metal.

[0017] The arrangement 1 further comprises at least one first pair of profile rollers, wherein the pair includes at least one upper profile roller 4a and at least one lower profile roller 4b, the profile rollers being arranged opposite each other. In one embodiment, the arrangement of rollers may comprise exactly one pair of profile rollers. In a preferred embodiment, the arrangement 1 comprises at least one further pair of profile rollers, which also includes an upper profile roller 5a and a lower profile roller 5b. The profile rollers are each configured such that the sheet metal 2 is formed into a Z-profile, the Z-profile being introduced into the sheet metal in a multi-stage bending process.The first pair of profile rollers 4a, 4b in the direction of movement 3 of the sheet 2 can be configured such that a first angle, preferably an angle between 30° and 80° and particularly preferably an angle between 50° and 70°, is generated between the outer and inner legs of the Z-profile to be formed. The second pair of profile rollers 5a, 5b in the direction of movement 3 of the sheet is preferably configured such that the desired angles are achieved between the legs of the Z-profile. In a preferred embodiment, the angles between the legs can be 90°, so that the legs of the Z-profile are perpendicular to each other.

[0018] In an alternative embodiment, the angles between the legs of the Z can each be less than 90°, preferably between 60° and 85°, with the two bending angles being equal so that the outer legs of the Z-profile are parallel to each other, but the middle leg is not perpendicular to them. As explained below, this can be advantageous when welding the turns / coils of the Z-profiled, bent, and coiled sheet metal.

[0019] Fig. Figure 2a shows a schematic sectional view of the first pair of profile rollers 4, comprising an upper profile roller 4a and a lower profile roller 4b. As shown in the embodiment, the upper and lower profile rollers 4a can each be made in two parts, such that the upper profile roller 4a has a first profile section 4a1 and a second profile section 4a2. The lower profile roller has a first profile section 4b1 and a second profile section 4b2. The respective profile sections can rotate on their respective axes, which are arranged vertically and horizontally in their respective positions. The profile sections can have the same or any other diameter. Alternatively, the profile sections of the lower or the upper profile roller can each have different diameters, with the profile sections of the upper profile roller and the lower profile roller, respectively, being mounted on the same axis.

[0020] With reference to the height of the sheet metal 2 to be profiled, the profile section rolls are arranged with a first vertical distance v1 and with a first horizontal distance h1 to each other in such a way that first bending angles are created between the legs of the Z-profile.

[0021] Fig. Figure 2b shows a schematic view of a second pair of profile rollers 5a, 5b, which can also each be designed in two parts, such that the upper profile roller 5a has a first and a second profile section roller 5a1, 5a2, and the lower profile roller likewise has a first and a second lower profile section roller 5b1, 5b2. The relative arrangement of the second profile rollers 5a, 5b is typically chosen such that the desired bending angles between the legs of the Z-profile are still achieved. Typically, the respective profile sections of the upper and lower profile sections of the second pair of profile rollers have a larger vertical offset v2 and a smaller horizontal distance h2 than the profile rollers of the first pair of profile rollers, so that the bending angles of the Z-profile become larger, while the length of the middle leg of the Z-profile remains unchanged.

[0022] Furthermore, the device 1 can include one or more additional pairs of profile rollers for generating the Z-profile of the sheet metal 2, so that the sheet metal achieves the Z-profile in several stages. In this way, the profiling of the sheet metal 2 can be effected with at least one pair of profile rollers, preferably two pairs of profile rollers 4 and 5.

[0023] Regardless of the number of profile rollers in the device 1, the last profile roller in the direction of movement 3 of the sheet is preferably designed and mounted in such a way that it is suitable as a support for receiving a force which is exerted on the Z-profiled sheet 2 by the round bending rollers during the following described round and helical bending of the sheet 2.

[0024] The arrangement 1 of rollers further comprises at least one upper bending roller 7a and one lower bending roller 7b for round bending the Z-profiled sheet 2, wherein the sheet 2 is bent to the diameter of the tube and simultaneously the round-bent Z-profiled sheet is bent into a helix, so that the round-bent Z-profiled sheet partially overlaps and thus forms a continuous tube. The overlap is at most the length of one leg of the Z-profile of the profiled sheet 2.

[0025] In a preferred embodiment, the bending rollers are designed as a pair with an upper bending roller 7a, 8a and a lower bending roller 7b, 8b opposite each other, so that the roller arrangement 1 in a preferred embodiment has at least a first pair of bending rollers 7a, 7b and a second pair of bending rollers 8a, 8b.

[0026] The surfaces of the bending rollers each have a profile adapted to the Z-profile of the sheet metal 2 to be bent, so that the Z-profile of the sheet metal 2 is maintained during bending. Each profiled bending roller can have two sub-rolls, which may have different diameters, so that the sub-rolls can be mounted on a common axis. In one embodiment, the sub-rolls of each upper or lower roller can be mounted such that the respective sub-rolls can rotate independently of each other, so that the circumferential speed of a sub-roll is equal to the speed of the surface of one leg of the Z-profile of the sheet metal, and minimal slippage occurs between the respective sub-roll and the sheet metal 2.With reference to the surface of the sheet metal 2 to be bent, the roller parts of the upper bending roller have an offset in the vertical direction corresponding to the height of the Z-profile and are arranged with a horizontal distance corresponding to the Z-profile of the sheet metal, so that the Z-profiling of the sheet metal 2 is maintained.

[0027] In an alternative embodiment, a bending roll can be formed in one piece, with the profile of the bending roll being adapted to the Z-profile of the sheet metal 2. Such a one-piece bending roll can therefore rotate on an axis. Since slippage can occur between the bending roll and the profiled sheet metal 2 in a section of the one-piece profiled bending roll, the surface of the roll can be adapted accordingly. The surface of such a bending roll is typically hardened so that as little material as possible is removed from the bending roll due to the slippage between the roll surface and the sheet metal. For bending rolls with a comparatively large diameter, only the surface is hardened, for example, using an induction or flame hardening process. Rolls with smaller diameters are preferably through-hardened, for example, using a vacuum hardening process.

[0028] With reference to the position of the sheet 2, the at least one upper bending roller 7a and the at least one lower bending roller 8b are positioned vertically to each other in the vertical direction such that the lower roller 8b in conjunction with the upper roller 7a bends the Z-profiled sheet 2 round, i.e. into the radius of the tube, and preferably simultaneously bends it into the helix.

[0029] Fig. Figure 2c shows a schematic representation of a pair of bending rollers 7a, 7b. The embodiment shown here comprises a first upper roller part 7a1 and a second upper roller part 7a2, as well as a first lower roller part 7b1 and a second lower roller part 7b2. The upper roller parts 7a1 and 7a2 have different radii, the difference in radii corresponding to the length of the middle leg of the Z-profile of the sheet metal 2. Similarly, the lower roller parts 7b1 and 7b2 have different radii, the difference again corresponding to the height of the Z-profile. The roller parts are arranged according to the profile of the profiled sheet metal 2 such that both roller parts absorb the bending force and the Z-profile of the sheet metal 2 is maintained during bending. The upper roller 7a can be made in two parts, with the upper roller part 7a1 and the upper roller part 7a2 being mounted on a common axis of rotation.The upper roller parts 7a1 and 7a2 can preferably rotate independently of each other and thus independently follow the surface speed of a leg of the Z-profile sheet 2, so that the circumferential speed of a roller part is always equal to the speed of the adjacent leg and slippage between a roller part 7a1, 7a2 and the sheet 2 is avoided. Likewise, the lower roller 7b can similarly have two roller parts that can rotate at different circumferential speeds.

[0030] Furthermore, the partial rollers of each upper or lower roller 7a, 7b can each be driven accordingly, the respective drive being dimensioned such that the circumferential speed of a partial roller corresponds to the surface speed of the leg of the Z-profile.

[0031] In an alternative embodiment, an upper or lower roller can be formed in one piece. The outer surface of such a roller is adapted to the Z-profile of the sheet 2 and accordingly also has a Z-profile adapted to the Z-profile of the sheet 2. In this case, the circumferential speed can be set so that it corresponds to the surface speed of only one leg of the Z-profile.

[0032] Fig. Figure 3 shows a schematic perspective view of an arrangement 1 of rollers for profiling and bending a sheet 2, wherein the arrangement 1 comprises first profiling rollers 4a, 4b, second profiling rollers 5a, 5b and third profiling rollers 9a, 9b for profiling the sheet 2 into a Z-profile. The arrangement 1 further includes pairs of bending rollers 7 and 8.

[0033] The bending rollers of the device 1 are arranged such that they bend the sheet metal 2 into a round shape corresponding to the diameter of the tube, thereby bending it into a helix, the pitch of which is dimensioned such that the legs of two adjacent turns of the Z-profiled sheet metal 2 at least partially overlap. As in Fig. As shown in Figure 3, bending into a helix can be achieved by two successive bending rollers or pairs of bending rollers whose axes are not parallel to each other. While the axis of rotation of an upper roller in a pair of bending rollers is parallel to the axis of rotation of the respective lower roller, the axes of rotation of the two adjacent pairs of bending rollers are not parallel to each other.

[0034] As a schematic representation of the direction of the parallel axes of the bending roller pair 7, an axis 7c of the upper bending roller 7a of the roller pair 7a, 7b is shown, as is the axis 8c, representing the direction of the bending roller pair 8a, 8b. The axis 7c is not parallel to the axis 8c, but is tilted, so that the sheet 2 is bent not only into a radius, but also into a helix. The pitch and direction of the helix are determined in a manner known per se by the tilt angle of the bending rollers.

[0035] Fig. Figure 4a shows a schematic view of a helix formed by the Z-profiled and bent sheet metal 2. The dimensions of the Z-profile of the sheet metal 2 are chosen such that the two outer legs of the Z-profile are of equal length. The pitch of the helix is ​​dimensioned such that one pitch of the helix is ​​equal to the length of one outer leg, so that the two outer legs of the Z-profile completely overlap each other, thus creating a double-walled helix. Simultaneously, the middle leg of the Z-profile of the sheet metal rests against an outer edge of one of the outer legs. The distance between the inner and outer walls of the helix is ​​the height of the Z-profile of the sheet metal 2.

[0036] After the sheet metal 2 has been profiled into a Z-profile by means of the arrangement of rollers 1 and subsequently bent into the radius and the helix, adjacent threads of the helixed sheet metal 2 lie against each other, with the outer edges each abutting the middle leg of an adjacent thread of the Z-profiled and helixed sheet metal 2.

[0037] The coiled Z-profile sheet 2 is then firmly joined at the contact edges of two adjacent coils of the sheet 2; preferably, the adjacent coils of the Z-profile sheet are welded together. Accordingly, the adjacent coils of the Z-profiled and coiled sheet 2 are welded on the inside (see weld 10a) and on the outside (see weld 10b) of the resulting tube. The welding on the inside can be carried out independently of the welding on the outside, so that in one embodiment, the welding on the inside is carried out during the round and coil bending of the Z-profile sheet as soon as the previously bent coil contactes the sheet. The welding on the outside can likewise be carried out during the round and coil bending.

[0038] Fig. Figure 4b shows a schematic view of a section along the long axis through the helix of the Z-profile sheet 2, where A shows an enlarged section, with one strand of the Z-profile sheet depicted as a dashed line. The middle leg of the Z-profile sheet is welded to one leg of the next strand of the sheet on the inner side of the tube. On its outer side, the Z-profile sheet 2 is welded to the middle leg of the previous strand of the Z-profile sheet.

[0039] Finally, the tube produced in this way from the sheet metal strip 2 can be cut to a desired length.

[0040] Fig. Figure 5 shows the process steps for bending a tube with the arrangement of rollers described above.

[0041] In a first step, see 11, the sheet metal to be bent is fed to the arrangement of rollers 1 described above. This arrangement of rollers can optionally include conveyor rollers 6a and 6b, so that the sheet metal is fed to the profile rollers 4 and 5 via the conveyor rollers 6a and 6b. The conveyor rollers then cause the sheet metal 2 to be moved to the arrangement of rollers 1.

[0042] Subsequently, in step 12, the sheet is profiled into a Z-profile using at least one first pair of 4a-4b profile rollers. In a preferred embodiment, particularly if the thickness of the sheet so requires, the sheet 2 is further profiled using at least one additional pair of profile rollers 5a, 5b. In this case, the first pair of profile rollers profiles the sheet 2 into a Z-profile with first angles between the outer legs and the middle leg, and the second pair of profile rollers profiles the sheet 2 into a Z-profile with second, more acute angles between the outer legs and the middle leg. The length of the middle leg of the Z-profile of the sheet 2 can be selected such that the overlapping outer legs of the Z-profile rest against each other when the Z-profiled sheet is bent into a helix and then into a rounded shape.Alternatively, the length of the middle leg of the Z-profile can also be chosen so that the overlapping legs of the Z-profiled sheet have a distance from each other in the direction of the diameter of the helix when they are bent into a helix and rounded.

[0043] The Z-profiled sheet 2 is then bent into a circle and a helix, see step 13, so that adjacent turns of the helix partially overlap each other. In a preferred embodiment, the pitch of the helix can be selected such that the outer legs of two adjacent turns of the helix completely overlap, see also Fig. 4a-4b, and the outer legs of the Z-profile abut the middle leg of the Z-profile. In an alternative embodiment, the pitch of the helix can be selected such that the outer legs of the Z-profiled sheet only partially overlap and lie on top of each other in the direction of the radius of the helix.

[0044] In a further process step, overlapping turns of the helix are joined together, see step 14, for example by welding on the inside, see Fig. 4a, Fig. 4b Reference numeral 10a, and the outside of the helix, see Fig. 4a, Fig. 4b Reference numeral 10b, so that a solid tube is formed from the Z-profiled sheet metal bent into a helix. For this purpose, the device may include a suitable device, for example, a device for welding the Z-profiled and helixed sheet metal 2.

[0045] Alternatively, the overlapping legs of the Z-profiled and coiled sheet 2 can be firmly connected to each other by other methods, for example by gluing.

[0046] As an optional step, the welded helix, i.e. the resulting tube, can be cut to a desired length using conventional cutting methods and release agents.

[0047] In this way, a double-walled tube can be produced from a sheet 2 using the arrangement 1 of profile and bending rollers described above, wherein the inner wall and the outer wall of the resulting tube are connected to each other via the middle leg of the Z-profiled sheet bent into a helix, so that the double-walled tube has a high strength.

Claims

[1] Device for producing a double-walled tube from a sheet (2) comprising: at least one first pair of profile rolls (4a, 4b, 5a, 5b) for producing a Z-profile with a middle leg having a length and two outer legs in the sheet (2), wherein a pair of profile rolls (4a, 4b, 5a, 5b) has an upper profile roll (4a, 5a) and an opposing lower profile roll (4b, 5b), and at least one bending upper roll (7a) and one bending lower roll (8b) for producing a circular bend in the sheet (2), wherein the bending upper roll (7a) and the bending lower roll (8b) are arranged to simultaneously produce a helix in the sheet (2), such that adjacent turns of the helix partially overlap, a device for connecting a first passage of the helix with an adjacent second passage of the helix wherein the middle leg of the Z-profile has a length such that the overlapping outer legs of the Z-profile are spaced apart from each other in the direction of the diameter of the helix when they are coiled into a helix and rounded. [2] Device according to claim 1, further comprising a conveyor roller for conveying the sheet metal (2). [3] Device according to one of the preceding claims, wherein the upper profile roller (4a, 5a) comprises a first partial roller (4a1, 5a1) with a first diameter and a second partial roller (4a2, 5a2) with a second diameter. [4] Device according to one of claims 1 to 2 wherein the lower profile roller (4b, 5b) comprises a first partial roller (4b1, 5b1) with a first diameter and a second partial roller (4b2, 5b2) with a second diameter. [5] Device according to one of the preceding claims, wherein the device for connecting the first turn of the helix to a second turn of the helix is ​​a device for welding. [6] Device according to one of the preceding claims, wherein the device for connecting the first turn of the helix with a second turn of the helix is ​​provided to connect an outer edge of the Z-profile of one helix with the middle leg of the Z-profile of an adjacent turn of the helix. [7] Device according to one of the preceding claims, wherein the device for connecting the first turn of the helix with an adjacent second turn of the helix is ​​provided to connect the first turn of the helix with the second, adjacent turn of the helix on the inside and the outside. [8] Method for producing a double-walled tube from a long sheet (2), the method comprising the steps: Z-profiling (12) of the sheet (2) by means of at least one pair of profile rollers (4a, 4b, 5a, 5b) into a Z-profile with a middle leg having a length and two outer legs, and Round and helical bending (13) of the Z-profile sheet (2) using bending rollers (7a, 7b, 8a, 8b), wherein adjacent turns of the helix overlap, wherein the middle leg of the Z-profile has a length such that the overlapping outer legs of the Z-profile have a distance from each other in the direction of the diameter of the helix when they are bent into a helix and round, and Connecting adjacent passages of the spiral. [9] Method for producing a tube from a sheet (2) according to claim 8, wherein joining adjacent turns of the helix is ​​welding or bonding. [10] Method according to any one of claims 8 to 9 above, wherein the welding is carried out on the inside and on the outside of the helix. [11] Double-walled metal tube, wherein the inner wall and the outer wall are formed from a Z-profiled sheet bent into a helix, and wherein adjacent turns of the helix are connected to each other, wherein the outer wall has a radial distance to the inner wall. [12] Double-walled metal tube according to claim 11, wherein the Z-profile sheet has a middle leg and two outer legs, and wherein the outer legs of the Z-profile sheet bent into a helix are of equal length. [13] Double-walled metal tube according to one of claims 11 to 12 wherein one leg of the Z-profiled sheet is connected to the middle leg of the Z-profiled sheet. [14] Double-walled metal tube according to claim 13, wherein the connection is a weld or an adhesive bond. [15] Double-walled metal tube according to one of claims 11 to 13 wherein the metal tube has a helical weld or adhesive seam on its outer wall or its inner wall for joining adjacent passages.

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