Manufacture of pipes or tubes

(54) Designation Procedure for the production of helically wound tubes and tubes manufactured in the manner (56) Published Publications: US 3,982,414 (72-50) (57) Abstract:

A method of producing in helical form winding, along the entire winding edge, tubes of partially corrugated strip (1) of sheet or foil (1), the corrugated strip along a longitudinal edge (8), the outer shank (7) of which forms the band of the strip. edge and at the other longitudinal edge is provided with a deflection (4) in the same direction as the scales (8), that the strap is wound to a tube whereby the deflection (4) is caused to engage the scales (8), and that this joint is bent during compression to the side of the deflection to a seam (Q), whereupon at the place of this seam (9) an additional corrugation (10) is formed which in its one flank comprises the seam (9) (Figure 1). The invention also encompasses a tube thus produced.

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Background of the invention

The present invention relates to a method for producing, from at least partially and parallel to the longitudinal edges, thin sheet or foil corrugated strips, producing helically wound tubes which are seamed along the entire longitudinal edges of the strips, and produced in accordance with this method.

Previously known tubes of this kind are known in which the seams, which connect the entire longitudinal edges of the sheet or foil strips wound to the tube, lie in a surface parallel to the tube surface of the tube. The pipe corrugation is thus

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7905809-5 broken in the region of the rim of this known tube. Since the seam must have a certain width and the strips from which the pipe is wound are often relatively narrow, there is thus obtained an unfavorable relationship between the pipe surface provided with corrugations and the surface in which the seam is located. This adversely affects various properties of such pipes. The pipes are mainly corrugated in order to, as in the case of hoses, obtain a flexibility and also in order to be able to achieve relatively transverse curves and curves with small radii, respectively. Furthermore, due to their helical corrugation, such pipes are extensible and compressible, so that e.g. when piping is not necessary to cut the pipe to exact dimensions.

The known tubes, in which the seam lies in a surface parallel to the casing surface of the tube, have the disadvantage that, due to this placement and design of the seam, they cannot bend as well and with as small radii as tubes which are consistently corrugated. Such tubes are prepared by other methods. In this case, a tube of bands of the same or different materials is first wound in the same and also in. different directions in multiple layers, which immediately after being wound, are provided with helical corrugations. However, such pipes are not suitable for all applications, and for example, very thin metal foils may be reinforced or stiffened. other materials such as paper or plastic. For example, the heat resistance of such pipes to be considerably limited. Moreover, in the latter pipes, it is always necessary to take special measures to ensure that the individual tapes of the pipe hold together, even when the pipe is cut at the desired location.

In known seamed, corrugated pipes, it has also been found to be a disadvantage, especially in the case of excessive curvature, but also in repeated tensile stresses, the seam.

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₃ 7905809-5 at multiple bends is worn so that a typical damage with a tear shape similar to a flycatch strip occurs. Due to the axial smoothing of the ridge, these known tubes are not allowed to compress strongly in the axial direction. Of course, the compressive strength is less in the region of the crease than in the area of ​​the corrugations.

The object and the main features of the invention

The invention has for its object to avoid the disadvantages of the prior art described above and to offer a coiled line at least partially pre-corrugated strip, in which the longitudinal canoes of the strips are seamed, and the casing surface has an uninterrupted uniform corrugation. According to the invention, this can then be a single-layer or multi-layer tube.

A method of producing tubes of the type described initially, which solves this task, is characterized in that the strip along its one longitudinal edge is provided with a gutter-shaped corrugation or wave valley, the outer shank of which forms the one side edge of the belt, so that a flat portion is connected with said flat valley to the said height. and having a length substantially corresponding to the length of a flank, that the other longitudinal edge of the belt is provided with a deflection in the same direction as the wave valley, to which deflection is connected a second flat portion at the height of the wave peaks and having a length at least equal to twice the length of a flank, that the strap is wound to a tube such that the deflection engages in the wave valley and that connection during compression is bent towards the side of the deflection to a seam after which at the position of this seam an additional corrugation is formed which includes the seam in one of its flanks. For the manufacture of tubes consisting of two layers, the method is characterized in that after winding the first tube layer a second tube layer is similarly wound thereon, the seam being offset at least the width of a flattened corrugation and then wave valves or corrugations are formed at the position. for the creases during forming of, respectively, creases in one of the flanks of the corrugations formed. In this case, the scales are preferably formed with the seams always located on the same side of the flank of the scales. The tube is suitably

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7905809-5 flat wrapped in the area to be later formed as a ridge containing the ridge.

A pipe according to the invention made according to the previous method is characterized in that it is provided with corrugations of equal spacing. Most advantageously, it is so much compressed that the flanks of all the corrugations touch each other. In such a tube, the sheet metal strips are connected to each other along their longitudinal edges by bending ridges, which are arranged in the flank of a pipe wave valley. The fold is formed in such a way that a double undercut is obtained. The connection sockets located in the flank of the pipe wave valley are preferably located approximately radially relative to the pipe shaft.

In the method according to the invention, the seam is formed along the entire length of the belt wound to the tube in a special way, and thus no further working operations are required compared to the method used hitherto. The advantages obtained therein consist in that, in addition to the purely optically altered appearance of the tube, which shows a uniform throughput corrugation, it is also achieved that such a tube can be compressed and pulled apart optimally, whereby all the corrugations and also every wave valley in which the seam is absorbed are loaded uniformly and on the same. way. In this way, it is also possible to compress and disassemble such pipes substantially more often without thereby overloading the seam.

By arranging the ridge in the flank of a wave valley, one achieves the considerable advantage that this ridge, on the one hand, forms a double undercut and in addition is not subjected to tensile forces. In addition, by substantially extending the radius in the radial direction, a substantial improvement in the cam compressive strength of the entire pipe is achieved, particularly in the area of ​​the folds. A pipe according to the invention can be arranged in

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7905809-5 significantly less radius of curvature than has hitherto been possible at. folded tubes and it is furthermore possible to use thinner sheet and / or foil to make such tubes since the stresses in the area of ​​the folds are considerably reduced or completely eliminated. Heretofore, for the manufacture of such pipes, thin aluminum foils or aluminum sheets have been preferred, while the use of other metals has usually been associated with difficulties in the forming and shaping of the pipe. By the method according to the invention, such difficulties have been overcome so that pipes according to the invention can also be used foils of other metals and even those of special steel.

Due to the fact that the seam is radially arranged and the pipe is continuously corrugated, such pipes can be compressed much more strongly than has hitherto been the case and even so much that the flanks of the wave valleys touch each other. Despite this, such a pipe can again be pulled out very strongly and even so far that the corrugations are deformed into light U-shape and the pipe almost gets flat surface. This process can be repeated several times without cracking. When the pipe is stretched, the seam will no longer be subjected to tensile stress as it lies in the flank of a wave valley. The flexibility of the pipe is greatly improved.

In defined DIN standards, three different pipe types are defined, describing their shape and properties. These definitions are established because of the only possible manufacturing processes and design possibilities for such pipes to date. A pipe made in accordance with the invention realizes all the advantages and characteristics of all the three types of pipe mentioned.

Because the seams or seams of a pipe according to the invention are arranged radially against the pipe shaft, no longer a resilience will take place so that curvature, compression and disassembly of the pipe can be carried out without particularly great force and the pipe retains its shape once. received. As the cam compressive strength is improved, such a tube will not only become significantly more resistant to mechanical stresses, but it can also be made of a thinner material.

Since it has also become possible, in the process according to the invention, to easily manufacture two-layer pipes, in which the individual layers are independent of each other, but through the dense corrugation are nevertheless perfectly formed with each other, the possibility of making such pipes is obtained considerably more tightly than hitherto since the creases are located in different places and are designed completely independent of each other without any connection to each other. In this regard, in the past such bilayer pipes had considerable difficulties. Since, in a two-layer tube according to the invention, layered sheet or foil strips can easily be processed or also together and parallel to each strip can be wound strips of other materials, the invention offers the possibility of producing tubes which are provided or coated on the inside and / or outside. additional layers and may also have additional layers or layers between the two layers. A pipe according to the invention can thus have a wall consisting of several different layers or layers.

Description of the drawings

The invention will be described in more detail below with reference to embodiments shown in the accompanying drawings.

Figures 1a - 1d show the process of making _ ...

of a corrugated single-layer tube according to the invention,

Figures 2a - 2g show the process of preparation

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7905809-5 of a two-layer tube,

Figures Yes - Jg illustrate the process of making a two-layer tube with an additional outer layer or cover layer,

Figures 4a - 4g are the workflow for producing a two-layer tube with an additional inner layer or cover layer, and

Figures 5a - 5g show the process of making a two-layer tube with an additional layer or layer between the two layers.

Description of the working examples

According to the invention, first strips of thin sheet or foil which are unwound in a generally known manner from coils will be pre-corrugated in a special device, however, in accordance with the further processing, a flat area is left at both ends. One of the two edges and, more specifically, the one at which a slightly wider flat area remains is bent in the direction of the corrugation. and more precisely approximately at right angles, while at the other edge adjacent to a narrower flat area a wave valley is formed. Thereby, a band as shown partially in Figure 1a is formed in profile.

The middle portion of the strip denoted by 1 is provided with a number of longitudinal corrugations 2. On one side of the strip a wider area J has been left without corrugations, and the edge 4 of this side is bent approximately at right angles to the wave valley 5 lying between the corrugations 2 · On the other side of the belt there is a narrower, about half as wide area 6, which has been left without corrugations, the opposite edge 7 of the belt being formed as a corrugation 8.

If the strip 1 is wound helically on a core arranged above the profile shown in Figure 1a,

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7905809-5 corresponding to the left side of figure 1a is wound up and then the winding corresponding to the right side of figure 1a is provided, the corrugation 8 formed at the edge 7 of the strip overlies the deflection 4, as shown in figure 1a. As a result, when the band is wound up on the core, a certain control for the bands will be obtained,

In this way the strip wound on the core forms a seam in immediate connection to the winding process. Accordingly, in accordance with FIG. 1b, the corrugation 8 with the folded and hooked deflection 4 therein will be bent in the direction of the wider band part 3 which is without pre-forming, and on which the deflection 4 is arranged and after complete bending corresponding to FIG. 1c, the deflection will be pressed. fixed. It should be noted that already in Figure 1c, a joint section 9 has been formed with simple cutting. In the region of the now joined and coiled bands where the ridge 9 is located, in the immediate connection there will be formed a further corrugation 10 on the winding core in accordance with Figure 1d. The design of this corrugation takes place in such a way that the rim 9 is received in one of its flanks 11. This results in a double undercut seam and a pipe that is consistently and uniformly corrugated, which means that it is no longer necessary to consider that this is a single and sealed winding tube of individual sheet metal.

In Figures 2a-2g, the process of producing a two-layer tube is depicted in various stages and also here lies the core on which the pre-corrugated strip is wound to form a tube above the profile cross-section shown in Figs. It should be noted that the first steps for making the tube are the same as in the previously described method of manufacturing a single-layer tube.

In accordance with Figure 2a, first a band is wound on the core, the edges of which intersect with a corrugation 8

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7905809-5 and a deflection 4. The same reference numerals apply here as in the previously described embodiment.

In Figure 2b, it is shown that the corrugation 8 which overcomes the deflection 4 at one edge of the belt is bent to one side and more specifically to the side of the belt at whose edge the deflection 4 is arranged. In this case, the corrugation 8 will gradually be compressed so that first the two strip edges 4 and 7 abut one another and during the subsequent deformation and more severe deflection, they will grip behind and overlap.

After the gradual unbending of the corrugation 8 during compression, the stage 2c will be reached, whereby in the surface of the tube a seam 9 is formed immediately outside the winding mandrel, ie in the area between the regions 3 and 6 of the strip. Already at this stage an additional band 12 is wound on the tube formed on the winding mandrel with the band 1. This additional band 12 is also pre-corrugated with wave chambers 2 'and wave valves 5'. The band 12 also has a deflection 4 'on the rear edge of the winding direction, the distance 3' between the deflection 4 'and the first wave valley 5' being substantially smaller than the distance 3 between the deflection 4 and the first wave valley 5 in the first band 1.

Upon further winding the band 12 in the second layer, the image corresponding to Figure 2d is obtained. The opposite edges of the strip 12 have been placed with corrugation 8 'and free outer flank 7 over the deflection 4' so that the strip at this edge is already connected, upon application of this next winding of the strip 12 to the already completed tube forming the inner layer, it is ensured that the wide area 6 'without corrugations of the belt 12 in the second layer will abut the seam 9 · From Figures 2e and 2f it can be seen that on the belt 12 in the second layer

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7905809-5, a seam 9 'is formed, similar to that of the band 1 of the first layer. During successive bending and compression of the corrugation 8 ', which overcomes the deflection 4', the seam 9 'is formed. It can be seen from Figure 2f that the two seams 9 and 9 'are formed in the inner mantle surface of the tube between non-corrugated portions of the wound strips. These are the regions 3 and 6 of the band 1 and the areas 3 'and 6' of the band 12. In this case, the area 3 is initially as wide as the area 6 'and the area 6 is initially as wide as the area 3'. The widths of the regions are adapted to each other in such a way that in the final design of corrugations on the winding core in accordance with Figure 2g the incorporated seams 9 and 9 'are formed in the flanks to two successive corrugations 10 and 10'. On the completed tube shown in Figure 2g, one can no longer perceive optically or only after very careful examination that it is a folded tube and where the seams are located. The figure also clearly shows that the aforementioned advantages are achieved.

The following figures show in substantially the same operating procedures as in Figure 2 for the manufacture of pipes, which consist of strips which are provided with coatings or layers on one or both sides. In accordance with Figure 3, as a second outer band, a band, which is used, is used. Its later outer surface has a coating or lining illustrated by the parallel, dashed lines. This coating or lining 13 is material suitable for the purpose and can be made as a layer sprayed or otherwise applied to the tape, but may also be a film laid out on the tape or bonded to it.

The tube obtained according to Figure 3 is in practice a three-layer tube.

The corresponding operation shown in Figure 2 illustrates in Figure 4 the preparation of a tube which also has three layers, however, the third layer forms

7905809-5 an inner layer and e.g. an insulation against the wall of the pipe which protects this wall from external impact or provides a thermal or sound insulation. In this case, a band 1 is first wound on the core, which on the side which later forms the inner side is provided with a layer 14 in the form of a covering layer of paint, insulating agent or also in the form of an applied or fixed foil attached. The individual steps in the working process for producing the tube correspond to those shown in Figures 4a-4g and are the same as described in detail in connection with Figure 11.2. In this embodiment, it should be noted that an additional seal is obtained through the third layer 14 in particular in the groove 9 in the first inner band so as to obtain a well-sealed tube. In older pipes of this type this could not be achieved. In this way, one can also produce a tube, in which an inner layer or cover layer is only in the region of the seam to form a single or two-layer tube, with a special folding seal.

In accordance with the embodiment of Figure 5, the strip used to form the inner layer of the tube is provided with an outer surface layer. This outer surface layer of the first strip can be applied already in the preparation of the strip as described above in connection with Figures 3 and 4. However, the outer cover layer 15 of the inner band may also be wound at the stage corresponding to Fig. 5c before an additional band to be folded onto the core is wound onto the strip already folded thereon. The surface layer 15 then forms a second layer in the pipe wall and overcomes the already completed seam 9. In the layer 15 which later forms an intermediate layer between the two seamed strips, it can e.g. This is a fur-shaped layer of non-combustible mineral fibers so that this layer forms a heat and flame insulation. Such a structure of a pipe can e.g. be extremely advantageous for exhaust pipes in internal combustion engines. Between the two layers, which are collapsed with one another, there can also be arranged several simple wound layers, which also exhibit different physical properties.

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