Method for producing a wave structure on a tube and corresponding manufacturing device

Abstract

The invention relates to a method for producing a wave structure (2) on a tube (3) provided as a smooth tube, wherein clamping areas (5, 6) of the tube (3), spaced apart along a longitudinal central axis (4) of the tube (3), are clamped in clamping devices (7, 8) and the tube (3) is compressed by axially displacing the clamping devices (7, 8) relative to each other to form waves (14) of the wave structure (2). It is provided that during the forming process, a spacer (15) is arranged between each pair of the waves (14) formed by the compression to establish a defined distance between the two waves (14). The invention further relates to a manufacturing device (1) for producing a wave structure (2) on a tube (3).

Description

[0001] The invention relates to a method for producing a wave structure on a tube provided as a smooth tube, wherein clamping areas of the tube spaced apart along a longitudinal central axis of the tube are clamped in clamping devices, and the tube is compressed by axially displacing the clamping devices relative to each other to form the waves of the wave structure. The invention further relates to a manufacturing device for producing such a wave structure on a tube.

[0002] For example, German patent application DE 37 22 659 A1 is known from the prior art. This document describes a prefabricated pipe or hose, particularly for use between a carburetor and other components of an automobile, made from an extruded, intercooled, permanently bent, and cut-to-length tube, preferably made of polyamide. The pipe is characterized by corrugations in a bending section. It is manufactured by compressing the tube into an annular wave shape on a separate compression tool at room temperature. Production as continuous lengths is particularly recommended. The corrugations are formed with the tube preheated or at room temperature, optionally without a mandrel. The pipe is preferably made of polyamide.

[0003] The object of the invention is to propose a method for producing a wave structure on a tube provided as a smooth tube, which has advantages over known methods, in particular providing the wave structure with high dimensional stability and reproducibility.

[0004] According to the invention, this is achieved by a method for producing a wave structure with the features of claim 1. It is provided that during the forming process, a spacer is arranged between each pair of the waves formed by upsetting in order to establish a defined distance between the two waves.

[0005] Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims. It should be noted that the exemplary embodiments described in the description are not limiting; rather, any variations of the features disclosed in the description, the claims, and the figures are possible.

[0006] The process is used to create the corrugated structure on a pipe, which is initially provided as a smooth pipe. This means that the process starts with the smooth pipe, on which the corrugated structure is created, so that the pipe subsequently exists as a corrugated pipe. A smooth pipe is understood to be a pipe that has a uniform cross-section throughout its axial length. In contrast, the corrugated pipe has the corrugated structure, so that the cross-section of the corrugated pipe changes, at least in certain areas, in the axial direction, and in particular changes periodically.

[0007] The pipe is preferably designed and configured for use in a motor vehicle, particularly in the vehicle's engine compartment. In particular, the pipe is intended as a replacement for a hose or hose assembly. Such a hose, for example, consists at least partially of ethylene propylene diene monomer (EPDM) rubber. The hose exhibits high resistance, especially high resistance to various media, high pressure resistance, and / or high temperature resistance. It is also flexible, thus compensating for tolerances and / or movement, for example, during hose installation and / or during vehicle operation.

[0008] However, a disadvantage of such a hose is that it is comparatively expensive and also heavy. Furthermore, its installation space requirement is relatively large, as it is usually multi-layered and each layer has a specific thickness. Therefore, the aim of the inventive method is to produce the corrugated structure on the pipe in such a way that the pipe can serve as a replacement for the hose, namely that it is also characterized by high durability and / or the possibility of tolerance compensation or movement compensation.

[0009] For this purpose, the corrugated structure is manufactured on the tube in such a way that the tube is flexible in the area of ​​the corrugated structure. In other words, after the corrugated structure has been manufactured, the tube has an area of ​​higher flexibility and at least one area of ​​lower flexibility. In particular, the tube is more flexible in an area with the corrugated structure than in an area outside of it. This achieves the necessary flexibility of the tube precisely where it is required, for example, for the aforementioned tolerance compensation and / or movement compensation.

[0010] The pipe is preferably manufactured such that its dimensions are at most equal to those of the hose it replaces, but are smaller in at least some areas. For example, within the corrugated structure, an outer contour of the pipe lies partially on an envelope curve of the hose, while away from the corrugated structure it lies clearly within the envelope curve. This gives the pipe a space advantage of at least 1 mm, at least 2.5 mm, or at least 4 mm compared to the hose, away from the corrugated structure.

[0011] The flexibility of the tube is adjustable as desired by appropriately manufacturing the corrugated structure, in particular by selecting the appropriate spacing between the corrugations. This makes it possible, for example, to produce corrugated tubes with different stiffnesses or flexural strengths from identical smooth tubes. The tube is preferably made of a material that is less expensive than the hose material. For example, the tube is made of polyphthalamide (PPA), polyphenylene sulfide (PPS), polyamide (PA), especially PA 612, or polypropylene (PP). In particular, the tube is manufactured entirely from a single material, i.e., it consists entirely of the same material. However, it can also be multilayered, i.e., it has several radially arranged layers that are at least partially made of different materials.

[0012] In particular, the pipe is extruded before the corrugated structure is created, preferably within a controlled extrusion process during which the pipe's dimensions, especially its wall thickness and / or diameter, and / or the purity of the pipe material used in its manufacture are monitored. The pipe's high rigidity, apart from the corrugated structure, allows for rapid leak testing during assembly. Furthermore, the pipe can be fitted to a standard conduit with a fir-tree profile. No additional components are required to create a leak-proof connection. Using the pipe instead of a hose thus offers numerous advantages, particularly in the automotive sector. For example, the pipe is used as a coolant line. However, the pipe can also be used in other applications and / or in the form of other conduits.

[0013] The wave structure is created on the tube by clamping the tube at clamping points using clamping devices. Subsequently, the clamping devices are axially displaced relative to each other, so that the clamped sections of the tube within the clamping devices are also displaced relative to each other. Specifically, the clamping sections are moved towards each other by means of the clamping devices, so that the tube is deformed, i.e., compressed, in a forming zone located between the clamping sections. The compression of the tube occurs in such a way that it expands outwards in the radial direction with respect to the longitudinal center axis of the tube, thus creating the waves of the wave structure.In the forming process, the outer diameter of the tube is increased in certain areas, for example by at least 20%, at least 30%, or at least 40%, preferably by at least 50%, at least 60%, or at least 70%, and in particular by at least 20% to 70%, relative to the outer diameter of the tube before the shaft structure is formed. The shafts therefore have an outer diameter that is larger by one of the aforementioned values ​​than the outer diameter before their formation or the outer diameter of the tube outside the shafts.

[0014] To reliably achieve the aforementioned advantages of the tube, particularly compared to the hose, the shafts are to be manufactured with precisely defined dimensions. In particular, the distance between each pair of shafts is to be set to a defined value with high accuracy. For this purpose, it is provided that a spacer is positioned between the shafts during the forming process. More precisely, it is provided that the spacer is positioned next to a pre-formed first shaft, specifically such that the spacer rests against the first shaft in the axial direction. Preferably, the spacer also rests against the tube in the radial direction next to the first shaft in the axial direction to reliably prevent the tube from expanding immediately adjacent to the first shaft during the subsequent upsetting process.

[0015] The tube is then compressed by axially displacing the clamping devices and thus the clamping areas. This is done in such a way that a second shaft is produced directly next to the spacer. After the first shaft and the second shaft have been produced, the spacer is positioned between the two shafts, specifically resting against one of the two shafts on axially opposite sides. Preferably, the spacer remains between the shafts until the shaft structure is completely produced. This means, in particular, that the spacer is present as the first spacer, positioned between the first shaft and the second shaft.

[0016] To produce a third shaft of the wave structure, a second spacer is positioned on the tube, axially adjacent to the second shaft. The second spacer is positioned analogously to the first, as explained in the relevant sections. After the second spacer is in place, the tube is compressed again by repositioning the clamping devices, thus producing the third shaft. This process is repeated until all shafts of the wave structure are produced, specifically using a third spacer, a fourth spacer, and so on. By keeping the spacer in place between the shafts until the wave structure is complete, a precisely defined distance between the shafts is maintained.

[0017] It is possible for the spacing between the waves of the corrugated structure to be identical, and for the spacers to have identical axial extensions. However, it is also possible for the waves of the corrugated structure to be arranged at different distances from each other in order to achieve a defined stiffness profile of the tube in the axial direction. In this case, the spacers are designed with different axial extensions. Using the described procedure, the initially smooth tube is transformed into a corrugated tube with the corrugated structure, achieving particularly high dimensional accuracy. The waves are formed sequentially by gradually shortening the tube. This means that the waves of the corrugated structure are produced individually or, at most, in pairs.By producing each shaft or shafts, the tube is shortened; therefore, the length of the tube, i.e., its extension in the axial direction, decreases with each axial displacement of the clamping devices.

[0018] In half-section, the shafts are U-shaped. This means that each shaft consists of a first shaft ring and a second shaft ring, each originating from a base body of the tube and extending radially outwards. On their side facing away from the base body, the shaft rings are connected to each other by a connecting ring. In cross-section, the connecting ring is, for example, arc-shaped and can in this case also be called an arc ring. Preferably, the base body transitions smoothly, i.e., without discontinuities, into the shaft rings, which in turn transition smoothly into the connecting ring.

[0019] Preferably, the wall thickness of the tube in the base body and the wall thickness of the shaft ring and / or the connecting ring are identical or differ from each other by at most 45% or at most 35%, particularly by at most 25%, at most 15%, or at most 10%, the difference being caused by the forming of the shafts. Particularly preferably, the shafts are spaced apart from each other at a distance greater than the distance between the shaft rings. In particular, the distance between the shaft rings of one of the shafts is at most 20%, preferably at most 10%, at most 5%, or at most 1% of the distance between the shafts. The distance between the shafts is understood to be the distance between imaginary planes perpendicular to the longitudinal axis and intersecting the shafts at their centers in the axial direction.The distance between the wave rings is to be understood as the smallest distance in the axial direction between the wave rings, i.e., in particular a distance between the sides of the wave rings facing each other in the axial direction.

[0020] It should be noted that the specified spacing of the corrugated rings is present immediately after the corrugation structure has been manufactured and / or immediately after the pipe has been manufactured, for example, immediately after heat treatment of the pipe following the corrugation structure's production and / or after the pipe has been cut to length. However, the spacing may change during subsequent processing of the pipe. For example, the spacing changes when the pipe is bent, as this bending occurs particularly in the area of ​​the corrugation structure. Changes in the spacing can also occur due to environmental conditions, especially fluctuating environmental conditions, after the pipe has been manufactured.

[0021] In slightly different terms, the invention relates to a method for manufacturing a tube designed as a corrugated tube, wherein the tube is provided as a smooth tube, clamping areas of the tube spaced apart along a longitudinal central axis of the tube are clamped in clamping devices, and the tube is compressed by axially displacing the clamping devices relative to each other, so that the smooth tube is formed into the corrugated tube. It is again provided that during the forming process, a spacer is arranged between each pair of the corrugations formed by the compression in order to establish a defined distance between the two corrugations. The further procedure will become apparent from the explanations in this description.

[0022] A further development of the invention provides that the tube is tempered before upsetting. Tempering refers to adjusting the tube's temperature to a specific target temperature. Tempering can involve both adding heat to the tube and removing heat from it. In general terms, tempering describes heating and / or cooling the tube before upsetting. Specifically, the tube is heated from a starting temperature, meaning the upsetting process takes place at a higher temperature than the starting temperature. Heating the tube is achieved, for example, using an infrared heater and / or a hot air heater. Tempering the tube produces the corrugated structure with particularly high precision and prevents material weakening.

[0023] A further development of the invention provides that, prior to upsetting, a forming area located between the clamping areas is arranged in a support device. This support device has several axially adjacent support segments, each of which at least partially surrounds the tube and / or bears against the tube at least partially, and in particular continuously, in the circumferential direction, or has a radial distance from the tube that is at most 5% of the tube's outer diameter, preferably at most 2.5%, at most 1.5%, at most 1%, or at most 0.5% of the outer diameter. The forming area is the region of the tube in which the wave structure is produced. Viewed axially, the forming area lies between the clamping areas; for example, it extends directly from a first clamping area to a second clamping area, thus directly bordering both clamping areas.Before the shaft structure is manufactured, the clamping sections are inserted into the clamping devices and held firmly in place throughout the entire manufacturing process. The clamping sections are not released from the clamping devices during the manufacturing process. Instead, all shafts of the structure are manufactured before the clamping devices are released to free the clamping sections.

[0024] To ensure high dimensional accuracy of the shaft structure, the forming area is arranged within the support device. The support device preferably extends from one of the clamping areas to a second clamping area immediately before the shaft structure is formed, in particular from the first clamping device to the second clamping device. For example, the clamping devices are positioned on opposite sides of the support device before the shaft structure is formed. The support device has several support segments that lie side by side in the axial direction, and in particular, abut each other. Thus, before the shaft structure is formed, the support segments completely and continuously cover the entire forming area in the axial direction.

[0025] The support segments each circumferentially encircle the tube at least partially, preferably completely and continuously. The support segments may have one or more gaps circumferentially; for example, the gap(s) together extend over a maximum of 90°, 45°, or 30°, preferably over less, for example, a maximum of 15°, 10°, or 5°. Additionally or alternatively, the support segments bear against the tube circumferentially, at least partially, and in particular continuously.

[0026] However, it can also be provided that an annular gap remains in the radial direction between the support segments and the pipe, meaning that the support segments are continuously spaced apart from the pipe in the circumferential direction. The radial distance between the support segments and the pipe, or between the inner circumferential surfaces of the support segments facing the pipe, is preferably at most 5% of the pipe's outer diameter, more preferably at most 2.5%, at most 1.5%, at most 1%, or at most 0.5% of the outer diameter.

[0027] The outer diameter refers to the outer diameter of the smooth tube, or the outer diameter of the tube excluding the shafts and / or the wave structure. The spacing can be unevenly distributed around the circumference. Specifically, the radial distance between the support segments and the tube is intended to be at most one of the specified values ​​across the entire circumference. Preferably, one of the smaller distances is used; in particular, the distance is at most 1.5%, at most 1%, or at most 0.5%. In absolute terms, for example, the distance is intended to be at most 1 mm, at most 0.5 mm, or at most 0.25 mm. The support device prevents the tube from expanding where the support segments are located.

[0028] The support segments are movable in a radial direction. During the production of the shaft structure, one or more of the support segments are moved radially away from the tube, allowing the tube to expand in the area of ​​the removed support segments to form the shafts by upsetting the tube. This procedure enables high dimensional accuracy of the shaft structure and good reproducibility. It should be noted that the method can also use the support device independently of the spacer. In this case, the spacer is merely optional; the method is characterized in particular by the support device.

[0029] A further development of the invention provides that the support device is arranged on the tube such that it rests against the clamping devices on opposite sides. This approach has already been mentioned. The support device supports the tube across the entire forming area and allows the tube to be formed to produce the shafts only where the support segments are located radially away from the tube. Conversely, the expansion of the tube to form the shaft is prevented where the support segments are still in radial contact with the tube. The support segments are removed from the tube one after the other in a radial direction, thus achieving the aforementioned sequential forming of the shafts. This yields the advantages already explained.

[0030] A further development of the invention provides that, for forming each of the shafts, a first of the support segments is removed from the tube and the tube is compressed by means of at least one of the clamping devices in the direction of a second of the support segments located immediately adjacent to the first support segment, so that the shaft is formed between the second support segment and the at least one clamping device and subsequently rests against the second support segment, or that, for forming each of the shafts, a first of the support segments is removed from the tube and the tube is compressed by means of at least one of the clamping devices so that the shaft is formed between a third support segment and a fourth support segment and subsequently rests against the third support segment and the fourth support segment on opposite sides.For each shaft to be formed, one of the support segments is removed from the tube in the radial direction. The removed support segment is called the first support segment. After the removal of the first support segment, the clamping areas are shifted towards each other to compress the tube in the axial direction and form the respective shaft.

[0031] By upsetting the tube, it expands radially at the point where the first support segment was previously located, thus forming the shaft. The first support segment can be positioned so that the shaft remains spaced from it even after forming, particularly in the radial direction. However, to achieve exceptionally high dimensional accuracy, the first support segment can also be positioned and the tube formed in such a way that the shaft, after being upset, rests against the first support segment in the radial direction. With this approach, the shaft exhibits exceptionally high dimensional accuracy, even in the radial direction.

[0032] In any case, according to a first variant of the method, the tube is compressed such that the shaft is formed between the clamping device and the second support segment. Specifically, after compression, the shaft rests against the second support segment on one side and the clamping device on the other. Subsequently, the second support segment is also removed from the tube, while another second support segment adjacent to the first remains attached to the tube. Following this, another shaft is formed by compressing the tube at the position previously occupied by the second support segment, particularly after the spacer has been attached to the shaft, so that the spacer is located between the first and second shafts after the second shaft has been formed. This shaft lies between the second second support segment on one side and the clamping device on the other, specifically resting against them on opposite sides.

[0033] Alternatively, according to a second variant, the shaft is not formed between the support segment and the clamping device, but between two support segments, namely between the third and fourth support segments. These designations are chosen solely for clarity. The third or fourth support segment may correspond to the aforementioned second support segment; however, this is not mandatory. In the second variant, the third and fourth support segments are arranged on opposite sides of the first support segment, which is removed from the tube. In particular, they are located directly adjacent to the first support segment; for example, they are in contact with it, at least before its removal, especially in the axial direction.

[0034] The third and fourth support segments are spaced apart from each other, particularly by removing the first support segment located between them, and are moved towards each other during the upsetting of the tube. This creates the corrugation between the two support segments, which rest against them on opposite sides. Subsequently, the third and / or fourth support segments are removed from the tube, and one or more further corrugations are formed by upsetting the tube. Preferably, one or more spacers are arranged on the tube, specifically on the corrugation, before the tube is upsetting. It can be provided that the already formed corrugation is arranged between two spacers, particularly with the spacers resting against the corrugation on opposite sides.The advantages already mentioned are reliably achieved with the described procedure, regardless of the chosen variant.

[0035] A further development of the invention provides that during upsetting, either only one of the clamping devices is moved towards the other, or both clamping devices are moved, and / or that during upsetting, the support segments are held immovable relative to each other in the axial direction, or are moved towards each other by the axial movement of the clamping devices. Moving the clamping devices relative to each other means that either only one or both clamping devices are moved. It can therefore be provided that one of the clamping devices is held stationary while the other clamping device is moved towards it. In this case, it can be provided that the entire support structure remains stationary during upsetting or is also moved due to the movement of the clamping devices.For example, it is provided that when only one of the clamping devices is moved, the support device is also moved axially while the pipe is compressed. However, if both clamping devices are moved, this is preferably done in such a way that the support device remains stationary.

[0036] Additionally or alternatively, the support segments are designed to remain stationary relative to each other during upsetting, or to be displaced relative to each other. For example, it may be possible to remove a support segment located between two of the support segments from the tube and to manufacture the shaft, viewed axially, between the two remaining support segments by displacing them towards each other during upsetting. This has already been described previously. This method also achieves the high dimensional accuracy of the shaft structure.

[0037] A further development of the invention provides that, after the forming of the respective shaft, at least one of the support segments abutting the shaft is removed from the shaft and the spacer is instead arranged abutting the shaft. In other words, after the shafts are formed by upsetting the tube, the support segment, or at least one of the support segments, is replaced by the spacer. The support segment against which the last formed shaft abuts is removed from the tube, or at least one of the support segments that hold the shaft between them and abut it. Subsequently, the spacer is arranged such that it abuts this last formed shaft in the axial direction. The spacer has smaller dimensions than the support segment, so that during a subsequent upsetting of the tube, another shaft is formed, namely next to the spacer.This enables rapid and accurate shaping of the wave, especially with short cycle times.

[0038] A further development of the invention provides that at least some of the support segments, and in particular all of the support segments, are each integrated with one of several spacers. The spacer already mentioned is a component of the multiple spacers. In principle, it can therefore be provided that the spacer(s) is / are already arranged on the tube, particularly in the axial direction in overlap with one of the aforementioned support segments. In this case, the corresponding support segment is removed from the shaft, but the associated spacer remains attached to it. With such a procedure, the spacer and the support segment can together form a single component, which consequently integrates the spacer and the support segment.Preferably, each support segment is part of such a component, such that each support segment is associated with a spacer that remains attached to the tube or shaft when the respective support segment is removed. In particular, the support segment is arranged on the side of the spacer facing away from the shaft, so that it is supported or rests against the shaft via the spacer. In this case, it can also be said that the spacer is integrated into the support segment. For example, the spacer forms a section of the support segment that rests against the shaft. When the support segment is removed, the spacer remains attached to the shaft, but space is created on the side of the spacer facing away from the shaft to allow for the further forming of the shaft.This approach has the advantage that fewer elements need to be moved, in particular only the respective support element, but not the spacer.

[0039] A further development of the invention provides that, prior to upsetting, a support mandrel extending from a first clamping device to a second clamping device is arranged in the tube. The support mandrel extends through the tube such that it reaches at least from the first clamping device to the second clamping device, i.e., it is axially aligned with them. In particular, it extends completely through the tube in the axial direction, thus projecting axially over at least one of the clamping devices, but preferably over both clamping devices. The support mandrel has radial outer dimensions that correspond to or are slightly smaller than the inner dimensions of the tube. For example, the outer diameter of the support mandrel is at least 2%, at least 5%, or at least 7.5% smaller than the inner diameter of the tube.This ensures reliable shaping of the tube for forming the shafts.

[0040] A further development of the invention provides that the clamping of the clamping areas by means of the clamping devices is carried out such that the pipe is held in a force-fit connection between the support mandrel and a first clamping device in a first of the clamping areas, and in a second of the clamping areas it is fixed relative to a second clamping device and can be displaced relative to the support mandrel. As a result, the support mandrel is fixed relative to the first clamping device, but can be displaced relative to the second clamping device. The first clamping device engages the pipe in such a way that it is compressed in the first clamping area and held in a force-fit connection between the support mandrel and the first clamping device.

[0041] The second clamping device, however, engages the second clamping area in such a way that the support mandrel is movable relative to it. Thus, in the second clamping area, the tube is not compressed radially, or at most, it is compressed to such an extent that the support mandrel is not firmly locked relative to the second clamping device. This can be achieved, for example, by a specific design of a clamping jaw of the second clamping device, which preferably has a specific surface and / or geometry.

[0042] However, it is also possible for the clamping devices to use different clamping forces to secure the pipe relative to them. The first clamping device uses a first clamping force and the second clamping device uses a second clamping force, with the first clamping force being greater than the second clamping force to implement the aforementioned procedure. The first clamping force is thus chosen, for example, to compress the pipe further in the radial direction than the second clamping force. The described procedure allows for internal support of the pipe using the support mandrel.

[0043] A further development of the invention provides that the pipe is fixed axially in at least one of the clamping devices by arranging a support element on a side of the at least one clamping device facing away from the support device. This support element is stationary relative to the at least one clamping device and has a recess, through which the support mandrel extends, with dimensions that are smaller than the outer dimensions of the pipe. The support element serves to positively lock the pipe in the clamping device in at least one direction. For this purpose, the support element is stationary relative to the clamping device; in particular, it is connected to or attached to the clamping device.

[0044] The clamping device has a recess with radial dimensions that correspond at least to the outer diameter of the support mandrel. However, these dimensions are smaller than the outer dimensions of the tube, so that while the support mandrel can move through the recess, the tube cannot. The support element has a rim that defines the recess and acts as a support rim for the tube. At least temporarily, the tube rests axially against this support rim and is thus held in the clamping device in the direction away from the support.

[0045] It is possible for only one of the clamping devices to have such a support element, or for the support element to be assigned to only one of the clamping devices. Preferably, however, several support elements are present, namely on opposite sides of the clamping devices, in order to hold the tube in the respective clamping device. This allows for particularly precise manufacturing of the shaft structure and effectively prevents damage to the tube caused by excessive clamping force from the clamping devices.

[0046] A further development of the invention provides that the support mandrel has a temperature control element which is used, at least temporarily, to temperature-control the tube in the forming area. The temperature control element serves to control the temperature of the tube, at least in the forming area. Temperature control is understood to mean heating and / or cooling the tube. Particularly preferably, the tube is kept at the processing temperature in its forming area by means of the temperature control element until the corrugated structure is completely formed, i.e., until all the corrugations of the corrugated structure have been formed. This ensures high reproducibility of the corrugated structure as well as good fatigue strength of the tube.

[0047] A further development of the invention provides that the clamping devices are repositioned for the simultaneous forming of exactly one of the shafts or for the temporally overlapping forming of several shafts. In each case, the shafts are formed sequentially, meaning they are produced at least partially one after the other. However, it can be provided that, by repositioning the clamping devices, one or more shafts are formed temporally, particularly simultaneously. In the case of temporally overlapping forming of the shafts, those shafts are formed which, after the complete formation of the shaft structure, accommodate at least one further shaft between them. The temporally overlapping formed shafts are therefore not arranged directly next to each other. In any case, the high dimensional accuracy of the shaft is achieved.

[0048] A further development of the invention provides that, after the shafts have been manufactured, a fixing die is arranged encompassing the forming area between the clamping devices, which has fixing lamellae engaging between the shafts, or that the tube is fastened to the support mandrel on both sides of the forming area by means of fastening elements. In both variants, deformation of the tube, in particular of the shaft structure, after its manufacture is prevented. In particular, expansion of the shaft structure in the axial direction is prevented by preventing any dimensional change of the tube in the axial direction. This is achieved either by means of the fixing die or by means of the fastening elements and the support mandrel.

[0049] The clamping die encompasses the forming area, in particular, it completely encloses the shaft structure. The shaft structure is supported axially on opposite sides, thus preventing axial expansion. Additionally, the clamping die features clamping lamellae that engage between the shafts. Specifically, one clamping lamella engages between each pair of shafts, or conversely, one clamping lamella engages between each pair of shafts, so that clamping lamellae are arranged between all shafts. The clamping lamellae preferably rest against each shaft on opposite sides to support it axially. The clamping lamellae ensure high dimensional accuracy of the shafts.

[0050] Additionally or alternatively, the support mandrel serves to fix the tube. For this purpose, the tube is attached to the support mandrel on both sides of the forming area using the fastening elements. For example, the fastening elements compress the tube radially in such a way that the tube is held firmly between them and the support mandrel. Since the support mandrel is continuous and rigid, the use of the support mandrel and the fastening of the tube to it using the fastening elements reliably prevents any dimensional change of the tube in the axial direction. In any case, the tube's dimensional stability is ensured.

[0051] A further development of the invention provides that a fixing mold is used which has two fixing mold segments that are mounted to be displaceable relative to one another, between which the tube is arranged. The fixing mold segments are rotatably mounted relative to one another, for example, along a rotational axis. The fixing mold is thus opened to insert the tube into it and closed after insertion, so that the fixing lamellae engage between the waves of the wave structure. Such a design of the fixing mold enables particularly rapid fixing of the wave structure or the tube. Preferably, the fixing mold is made of a temperature-resistant and / or thermally conductive material, for example, metal. In this case, the fixing mold is also suitable for carrying out heat treatment of the tube after the wave structure has been manufactured.

[0052] A further development of the invention provides that the clamping devices and / or the support mandrel are removed from the tube only after the fixing die has been arranged encompassing the forming area and / or after the tube has been fastened using the fastening elements. Thus, the shaft structure or the tube is first fixed in the axial direction before the clamping device is released. If the shaft structure is fixed using the fixing die, the support mandrel is preferably also removed from the tube. Alternatively, however, it can remain in the tube, particularly during heat treatment of the tube. In any case, the described procedure achieves a high degree of dimensional accuracy of the tube or the shaft structure.

[0053] A further development of the invention provides that the tube, together with the fixing mold and / or the support mandrel and the fastening elements, is fed to a temperature control unit, by means of which the tube is thermally treated. In a first embodiment, the tube is received in the fixing mold; optionally, the support mandrel can also be arranged in the tube. In a second embodiment, the tube is fixed by means of the support mandrel and the fastening elements. Thus, in the first embodiment, the tube is fed to the temperature control unit together with the fixing mold, and in the second embodiment, together with the support mandrel and the fastening elements. Naturally, a combination of the two embodiments is possible, so that the fixing mold, the support mandrel, and the fastening elements are all used to fix the tube, particularly during the thermal treatment.

[0054] The temperature control unit is used to perform the thermal treatment of the pipe. Thermal treatment refers to tempering the pipe; for example, the pipe's temperature is adjusted to a specific fixing temperature during the process. Thermal treatment can therefore involve both heating and cooling the pipe. The thermal treatment is carried out in such a way that the pipe, or rather its corrugated structure, retains its shape after the treatment, meaning that no spontaneous deformation of the corrugated structure occurs during normal use of the pipe due to internal stresses or forces within the pipe.

[0055] A further development of the invention provides that the temperature control device first heats the tube, in particular using hot air and / or steam, and then cools it, in particular using cold air and / or cold water. The heating and cooling are carried out using a specific temperature control medium, i.e., hot air and / or steam or cold air and / or cold water, respectively. The tube is exposed to the temperature control medium, for example, by a flow of the temperature control medium over the tube. Additionally or alternatively, the temperature control medium can also flow through the tube, particularly if the support mandrel was removed from the tube before the thermal treatment. During the thermal treatment, the tube is first heated to the fixing temperature and then cooled again, in particular towards the ambient temperature or the initial temperature of the tube, preferably down to this temperature.This ensures high dimensional stability of the pipe.

[0056] A further development of the invention provides that, after the forming of the shafts, particularly after the heat treatment of the tube, the tube is stress-relieved and cut to length. Stress-relieving the tube means removing the fixation of the tube or the shaft structure, for example, by removing the fixing mold and / or the fastening elements. Stress-relieving is carried out in such a way that a dimensional change of the tube in the axial direction is permitted, allowing the tube to expand by equalizing internal stresses and / or internal forces. Stress-relieving is preferably carried out over a specific period of time and / or until the rate of change of dimensions in the axial direction is less than a threshold value. After stress-relieving, the tube is cut to length, i.e., a specific length of the tube is set by removing material. Stress-relieving and cutting to length results in high dimensional accuracy of the tube.

[0057] A further development of the invention provides that, after cutting to length, the geometry of the shafts is measured and compared with a target geometry. A component is identified as compliant if its geometry corresponds to the target geometry within a defined tolerance, and a component is identified as defective if its geometry deviates from the target geometry even when considering the tolerance. The geometry can be measured in any way, for example, optically and / or tactilely. The geometry describes, in particular, the distance between the shafts. If the geometry does not correspond to the target geometry within the tolerance, the tube is considered unsuitable for its intended use. Accordingly, the tube is declared a defective component.Otherwise, if the measured geometry matches the target geometry, the component is assumed to be suitable for its intended use and is identified as the correct component. This ensures high product quality of the pipe.

[0058] The invention further relates to a manufacturing device for producing a wave structure on a tube provided as a smooth tube, in particular for carrying out the method according to the explanations in this description, wherein the manufacturing device is designed and configured to clamp clamping areas of the tube spaced apart from one another in the direction of a longitudinal central axis of the tube in clamping devices and to upset the tube by axially displacing the clamping devices relative to one another to form waves of the wave structure. The manufacturing device is also designed and configured to arrange a spacer between each pair of the waves formed by upsetting during the forming process in order to set a defined distance between the two waves.

[0059] The advantages of such a design of the manufacturing device and such a procedure for manufacturing the pipe have already been mentioned. Both the manufacturing device and the method for operating it may be further developed as explained in this description, and reference is made to these explanations in that regard.

[0060] The invention also relates to a method for producing a wave structure on a smooth tube, wherein clamping areas of the tube spaced apart along a longitudinal central axis of the tube are clamped in clamping devices, and the tube is compressed by axially displacing the clamping devices relative to each other to form the waves of the wave structure. It is provided that, prior to compression, a forming area located between the clamping areas is arranged in a support device, which has several axially adjacent support segments, each of which encompasses the tube and bears continuously against the tube in the circumferential direction. With regard to possible advantageous embodiments of the method, reference is again made to the present description.

[0061] The features and combinations of features described in the description, in particular those described in the following figure description and / or shown in the figures, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention, in particular the scope of the claims. Thus, embodiments that are not explicitly shown or explained in the description and / or the figures, but which emerge from or can be derived from the explained embodiments, particularly within the scope of the claims, are also to be considered as encompassed by the invention.

[0062] The invention is explained in more detail below with reference to the exemplary embodiments shown in the drawing, without limiting the invention. The drawing shows: Fig. 1 a schematic representation of a manufacturing device for producing a wave structure on a tube provided as a smooth tube, and the tube present in the manufacturing device during a first manufacturing step of a first embodiment of a manufacturing process, Fig. 2 a schematic representation of the manufacturing device and the tube during a second manufacturing step, Fig. 3 a schematic representation of the manufacturing device and the tube during a third manufacturing step, Fig. 4 a schematic representation of the manufacturing device and the tube during a fourth manufacturing step, Fig. 5 a schematic representation of the manufacturing device and the tube during a manufacturing step in a second embodiment of the manufacturing process, Fig. 6 a schematic representation of the manufacturing device and the tube during a manufacturing step in a third embodiment of the manufacturing process, Fig. 7 a schematic representation of another area of ​​the manufacturing device and the tube, wherein the wave structure of the tube is arranged in a fixing form, Fig. 8 a schematic representation of an area of ​​the fixing form, as well as Fig. 9 A schematic representation of the manufacturing apparatus and the tube, wherein the tube is attached to a support mandrel passing through the tube using fastening elements.

[0063] The Fig. Figure 1 shows a schematic representation of a manufacturing device 1 for producing a wave structure 2 (not yet shown) on a tube 3. The tube 3 is initially a smooth tube, meaning it has a constant cross-section along its longitudinal axis 4. In particular, the wall thickness of the tube 3 is constant throughout in the axial direction. The tube has a first clamping area 5 and a second clamping area 6, with the first clamping area 5 being clamped in a first clamping device 7 and the second clamping area 6 in a second clamping device 8. A forming area 9 of the tube 3 lies between the clamping areas 5 and 6. The wave structure 2 is to be produced in this forming area 9.

[0064] To achieve high dimensional accuracy in the production of the wave structure 2, the forming area 9 is held in a support device 10, which consists of several support segments 11, of which only a few are shown here as examples. The support segments 11 completely and continuously encircle the tube 3 in the circumferential direction with respect to the longitudinal center axis 4 and are in continuous contact with the tube in the circumferential direction. Accordingly, the support device 10 and its support segments 11 support the tube 3 radially outwards. To support the tube 3 radially inwards, a support mandrel 12 is incorporated into the tube 3. The support mandrel 12 extends through the tube 3 from the first clamping device 7 to the second clamping device 8. In particular, it projects beyond the clamping devices 7 and 8 on opposite sides, thus protruding from them.

[0065] In the first manufacturing step shown here, the tube 3 is almost completely enclosed in the clamping devices 7 and 8 and the support device 10. In particular, the clamping devices 7 and 8 are each directly adjacent to the support device 10. Furthermore, the clamping devices 7 and 8, together with the clamping sections 5 and 6 clamped within them, are displaceable in the direction of arrow 13, namely in opposite directions along the longitudinal center axis 4.

[0066] The Fig. Figure 2 shows the manufacturing device 1 and the tube 3 in a second manufacturing step, again only schematically. In the second manufacturing step, one of the support segments 11 is removed, in particular spaced radially away from the tube 3. This results in a gap between the support device 10 and one of the clamping devices 7 and 8, in the illustrated embodiment the first clamping device 7.

[0067] The Fig. Figure 3 shows the manufacturing device 1 and the tube in a third manufacturing step. In this step, the clamping devices 7 and 8 are moved towards each other, for example, by moving the first clamping device 7 in the direction of the second clamping device 8 and holding the second clamping device 8 in a fixed position. Since the tube 3, or rather its clamping areas 5 and 6, are held firmly in the clamping devices 7 and 8, moving the clamping devices 7 and 8 towards each other compresses the tube 3 axially. It widens where the support segment 11 was previously removed, so that a shaft 14 of the shaft structure 2 is formed there.

[0068] The Fig. Figure 4 shows the manufacturing device 1 and the tube 3 in a fourth manufacturing step. During this step, the support element 11, which is directly adjacent to the straight shaft 14, is removed and replaced by a spacer 15. The spacer 15 is positioned directly adjacent to the straight shaft 14, so that the shaft 14 rests against the first clamping device 7 on one side and against the spacer 15 on the other. The spacer 15 is mounted so that it can be displaced axially relative to the support segments 11 of the support device 11.

[0069] Subsequently, by further shifting the clamping devices 7 and 8 relative to each other, the tube 3 is compressed further in the axial direction, so that another shaft 14 is formed between the support device 10 and the spacer 15. This process, consisting of removing one of the support segments 11 and replacing it with a spacer 15, followed by compression of the tube 3 to form another shaft 14, is repeated until all shafts 14 of the shaft structure 2 have been formed. This is the case, in particular, when all remaining support segments 11 have each been replaced by a spacer 15, or when all support segments 11 have been removed from the tube 3.

[0070] The Fig. Figure 5 shows the manufacturing device 1 and the tube 3 for a second embodiment of the manufacturing process. This embodiment is fundamentally similar to the first embodiment, so full reference is made to the corresponding descriptions, and only the differences are discussed below. These differences lie in the fact that two of the shafts 14 are manufactured in overlapping or even simultaneous stages by removing two of the support segments 11 and moving the clamping devices 7 and 8 axially towards each other, so that a shaft 14 is formed on each side of the remaining support device 10. Spacers 15 are also used here to ensure high dimensional accuracy of the shaft structure 2.

[0071] The Fig. Figure 6 shows the manufacturing direction 1 and the tube 3 for a third variant of the manufacturing process. This variant is also similar to the first embodiment, so reference is made to the corresponding description, and only the differences are discussed below. These differences lie in the fact that the shaft 14 is not formed between the support device 10 and one of the clamping devices 7 and 8, but between two of the support segments 11. For this purpose, one of the support segments 11 is removed from the tube 3, and the remaining support segments 11 are pressed towards each other by moving the clamping devices 7 and 8. As a result of this compression, the tube 3 bulges out, and the shaft 14 is formed. The support segments 11 are axially displaceable relative to each other for this purpose.

[0072] The Fig. Figure 7 shows the manufacturing device 1 and the tube 3 in a further schematic representation, with a temperature control unit 16 of the manufacturing device 1 being shown. It can be seen that the tube 3 is arranged in the temperature control unit 16 for thermal treatment. The corrugated structure 2 is arranged in a fixing form 17, which on the one hand prevents the corrugated structure 3 from expanding in the axial direction and on the other hand maintains the defined distance between the corrugations 14. For this purpose, the fixing form 17 preferably has fixing lamellae 18 that engage between the corrugations 14 and bear against them on opposite sides.

[0073] The Fig. Figure 8 shows a schematic representation of the fixing mold 17, more precisely a fixing mold segment 19 of the fixing mold 17. The fixing mold 17 has two such fixing mold segments 19, which are pivotably mounted next to each other. In each of the fixing mold segments 19, a negative 20 of the wave structure 2 is formed, in which the fixing lamellae 18 are particularly visible.

[0074] The Fig.Figure 9 shows a schematic representation of the manufacturing device 1 and the tube 3, wherein the tube 3 is clamped to the support mandrel 12 using fastening elements 21. The shaft structure 2 is shown only in a highly schematic manner. It is intended that the clamping devices 7 and 8 (not shown here) are removed from the tube 3 only after the tube 3 has been attached to the support mandrel 12 on opposite sides of the shaft structure 2 using the fastening elements 2. This also prevents the shaft structure 2 from expanding axially. Preferably, the tube 3 with its shaft structure 2, together with the support mandrel 12 and the fastening elements 2, is fed into the temperature control unit 16. Support elements 22 are also shown, by means of which the tube 3 is additionally fixed axially.In particular, the support elements 22 are part of the clamping devices 7 and 8 or are used together with the clamping devices 7 and 8 to reliably hold the tube 3 in the axial direction.

[0075] In any case, the tube 3 is provided with the corrugated structure 2 with a high degree of process reliability using the manufacturing device 1 presented here. Due to the use of the spacers 15, the manufactured corrugated structure 2 is very uniform, so that the tube 3 exhibits precisely defined properties, particularly with regard to its stiffness and flexibility. Compared to a corrugated tube, the tube 3 produced using the manufacturing device 1 offers the advantage of a significantly more uniform wall thickness. Accordingly, the tube 3 also meets demanding strength requirements, especially with regard to burst pressure.

[0076] The corrugated structure 2 is in a crimped form. This results in a very uniform wall thickness. In particular, the wall thickness of the pipe 3 across the corrugated structure 2 is at least similar to the wall thickness of the pipe 3 outside of the corrugated structure 2. Furthermore, the extrusion speed of a corrugated pipe is very low compared to a smooth pipe. Since the corrugated structure 2 is not produced along the entire length of the pipe 3, the manufacturing efficiency of the pipe 3 is increased despite the additional work step. REFERENCE MARK LIST 1 Manufacturing device 2 wave structure 3 pipe 4 Longitudinal center axis 5 1. Clamping range 6 2. Clamping range 7 1. Clamping device 8 2. Clamping device 9 Forming area 10 Support device 11 Support segment 12 support pins 13 Arrow 14 wave 15 spacers 16 Temperature control unit 17 Fixing form 18 fixing lamella 19 Fixing form segment 20 Negativ 21 Fastening element 22 Support element QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 37 22 659 A1

[0002]

Claims

Method for producing a wave structure (2) on a tube (3) provided as a smooth tube, wherein clamping areas (5, 6) of the tube (3) spaced apart from each other in the direction of a longitudinal central axis (4) of the tube (3) are clamped in clamping devices (7, 8) and the tube (3) is compressed by axially displacing the clamping devices (7, 8) relative to each other to form waves (14) of the wave structure (2), characterized in that during the forming process a spacer (15) is arranged between each pair of the waves (14) formed by the compression in order to set a defined distance between the two waves (14). Method according to claim 1, characterized in that, prior to upsetting, a forming area (9) located between the clamping areas (5, 6) is arranged in a support device (10) which has several support segments (11) lying next to each other in the axial direction, each of which at least partially surrounds the tube (3) and / or bears at least partially against the tube (3) in the circumferential direction or has a distance from the tube in the radial direction which is at most 5% of an outer diameter of the tube. Method according to one of the preceding claims, characterized in that the support device (10) is arranged on the tube (3) such that it rests against the clamping devices (7, 8) on opposite sides. A method according to one of the preceding claims, characterized in that, for forming each of the shafts (14), a first of the support segments (11) is removed from the tube (3) and the tube (3) is compressed in the direction of a second support segment (11) located immediately adjacent to the first support segment (11) by means of at least one of the clamping devices (7, 8) to form the respective shaft (14), so that the shaft (14) is formed between the second support segment (11) and the at least one clamping device (7, 8) and subsequently rests against the second support segment (11), or that, for forming each of the shafts (14), a first of the support segments (11) is removed from the tube (3) and the tube (3) is compressed in the direction of the respective shaft (14) by means of at least one of the clamping devices (7, 8).so that the wave (14) is formed between a third support segment (11) and a fourth support segment (11) and then rests on opposite sides against the third support segment (11) and the fourth support segment (11). Method according to one of the preceding claims, characterized in that during upsetting only one of the clamping devices (7, 8) is moved towards the other of the clamping devices (7, 8) or both clamping devices (7, 8) are moved, and / or that during upsetting the support segments (11) are held immovable in the axial direction relative to each other or are moved towards each other by axially moving the clamping devices (7, 8). Method according to one of the preceding claims, characterized in that after forming the respective shaft (14) one of the support segments (11) abutting the shaft is removed from the shaft (14) and instead the spacer (15) is arranged abutting the shaft (14). Method according to one of the preceding claims, characterized in that at least some of the support segments (11) are each integrated with one of several spacers (15). Method according to one of the preceding claims, characterized in that a support mandrel (12) extending from a first of the clamping devices (7, 8) to a second of the clamping devices (7, 8) is arranged in the tube (3) before upsetting. Method according to one of the preceding claims, characterized in that the clamping of the clamping areas (5, 6) by means of the clamping devices (7, 8) is carried out in such a way that the tube (3) is held in a force-fit position in a first of the clamping areas (5, 6) between the support mandrel (12) and a first of the clamping devices (7, 8) and is fixed in a second of the clamping areas (5, 6) relative to a second of the clamping devices (7, 8) and is displaceable relative to the support mandrel (12). Method according to one of the preceding claims, characterized in that the tube (3) is fixed in at least one of the clamping devices (7, 8) in the axial direction by arranging a support element (22) on a side of the least one clamping device (7, 8) facing away from the support device (10), which is stationary relative to the at least one clamping device (7, 8) and has a recess penetrated by the support mandrel (12) with dimensions that are smaller than the outer dimensions of the tube (3). Method according to one of the preceding claims, characterized in that the support mandrel (12) has a temperature control element which is operated at least temporarily for temperature control of the tube (3) in the forming area (9). Method according to one of the preceding claims, characterized in that the clamping devices (7, 8) are relocated for the simultaneous forming of exactly one of the shafts (14) or for the temporally overlapping forming of several shafts (14). Method according to one of the preceding claims, characterized in that after the shafts (14) have been manufactured, a fixing form (17) is arranged encompassing the forming area (9) between the clamping devices (7, 8), which has fixing lamellae (18) engaging between the shafts (14), or that the tube (3) is fastened to the support mandrel (12) on both sides of the forming area (9) by means of fastening elements (21). Method according to one of the preceding claims, characterized in that the clamping devices (7, 8) and / or the support mandrel (12) are removed from the tube (3) only after the fixing form (17) encompassing the forming area (9) has been arranged and / or after fastening by means of the fastening elements (21). Method according to one of the preceding claims, characterized in that the tube (3) together with the fixing form (17) and / or the support mandrel (12) and the fastening elements (21) is supplied to a temperature control device (16) by means of which a thermal treatment of the tube (3) is carried out. Manufacturing device (1) for producing a wave structure (2) on a tube (3) provided as a smooth tube, in particular for carrying out the method according to one or more of the preceding claims, wherein the manufacturing device (1) is provided and configured to clamp spaced-apart clamping areas (5, 6) of the tube (3) in clamping devices (7, 8) in the direction of a longitudinal central axis (4) of the tube (3) and to compress the tube (3) for forming waves (14) of the wave structure (2) by axially displacing the clamping devices (7, 8) relative to each other, characterized in that the manufacturing device (1) is also provided and configured to arrange a spacer (15) between each pair of the waves (14) formed by the compression during the forming process in order to set a defined distance between the two waves (14).

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