Manufacture of pipes or tubes

© Start of patent duration: Longest possible duration:

t issued:

Inventor:

1985 03 15

1985 10 25 © Dependence:

AT 378 924 © References contemplated by the prior art:

AT-PS 284600 US-PS 3247692

CH-PS 83004 US-PS 3913623

FR-PS 1307015 US-PS 3938558

U.S. Patent 2,282,176

Nr.378924

The invention relates to a method for the production of pipes, in which initially strips of thin sheet metal or of a film are at least partially grooved and parallel to the longitudinal edge and subsequently wound into a folded threaded pipe, wherein the fold by nesting, folding and then crimping of opposing edge bends of the strip wound to the tube is made and the fold lies in the flank of a groove, and on pipes produced by this method.

According to US Pat. No. 3,982,414 it is known to produce tubes according to the method described above, wherein the fold is left in the place where it was prepared, formed and shaped. Therefore, the required for folding Randabwinklungen (hooks) must be matched to the general configuration of the pipe grooves that the hooks on the one hand without difficulty nesting on winding, on the other hand, but then only by the action of preferably roller-shaped printing tools inside and outside without any errors further deformed, bent together and can be compressed to the fold. This presupposes that in tubes in which the folds lie in the flank of a rib, this rib may at most have an opening angle of 45 °, but preferably greater. Otherwise it would not be possible at all to bring the two hooks against each other and fold them into one another. It is evident that finned tubes, whose ribs have an opening angle of 45 °, but preferably larger, can not necessarily be referred to as fully flexible tubes and certainly are not able to absorb significant changes in length. Tubes made by this process are also known from US Pat. No. 3,938,558 or No. 2,282,176.

Furthermore, pipes are known in which the fold, which connects the entire longitudinal edges of the pipe or foil strip wound to the tube, lies in a parallel surface to a jacket surface enveloping the tube. The scoring of the tube is thus interrupted in these tubes in the rebate. Since the folds must have a certain width and the strips from which the tubes are wound, in many cases are relatively narrow, this results in a rather unfavorable relationship between the surface of the tube, which is provided with grooves, and the surface of the tube in which the folds lie. It has significant adverse effects on various properties of such pipes. The tubes are therefore essentially grooved, in order to achieve flexibility, similar to hoses, and also to be able to provide relatively narrow bends or bends with a small radius during laying. Furthermore, such tubes are due to their helical grooving extendable or compressible, so that it is not necessary, for example, for laying, cut them to exact dimensions.

Furthermore, a method for the production of continuously grooved tubes is known, being initially wound from strips of the same or different material in the same direction and in opposite directions in several layers tubes, which are then immediately after they are formed by winding, provided with helical grooves. However, such pipes are not suitable for all purposes, it can, for example, only very thin metal foils are used, which are to be reinforced or stiffened with other materials, such as paper or plastic. As a result, for example, the heat resistance of such pipes is considerably limited. Moreover, in the latter tubes always special measures are required to ensure cohesion of the tube in the individual wound strips, u.zw. even if the pipe is separated at any point.

In the known folded, grooved pipes has also been found to be disadvantageous that at too narrow a bend, but especially in multiple stress on train ruptures during multiple stretching of the fold, so that a typical damage caused by the tearing as a flypaper shape. Because of the smooth in the axial direction folds such known pipes can not compress very much in the axial direction. Of course, the peak compressive strength in the region of the folds is considerably lower than in the region of the grooves.

The object of the invention has been found to be known, the disadvantages described above

To avoid manufacturing method and to provide a partially helically wound from at least partially grooved strip tube in which the longitudinal edges of the strips are folded, and in which an uninterrupted uniform grooving of the lateral surface is present. According to the invention may be a single or multilayer pipe.

Nr.378924

To solve the problem, a method for producing pipes of the type described above, characterized in that the pre-scored with rounded, steep-flank ribs strip initially at one longitudinal edge with a rib whose outer limb forms the edge, and at the other longitudinal edge an angling in the same direction as the rib provided and then wound to the pipe, wherein the bend is introduced into the rib and then this compound is folded over to the side of the bend in compression to the fold in a cylindrical surface coaxial with the lateral surface of the tube and finally at the location of this fold another rib is formed, which fold in one of its flanks Contains with the rib base facing fold edges.

A tube produced by the above method is provided with grooves at equal intervals throughout. The essential difference of the invention over the prior art is the fact that when winding the grooved strips of the fold is not prepared in situ, but on a coaxial with the outer surface of the tube surface, preformed and finally formed. Only after complete completion of the fold (or the folds in several layers) in the tube to be assigned to the folds ribs are formed. The tube is so to speak further formed and completed on the winding machine by forming these ribs. There is also a certain amount of creeping in terms of length, since at least one additional rib is formed.

A quite significant advantage of this new method is, inter alia, that grooved tubes can be produced which are fully flexible, ie in which the flanks of the ribs are steep and have only a very slight inclination against the normal plane to the tube axis. Thus, not only very tight bending radii can be produced with these tubes, but the tubes can be compressed to the mutual contact of the groove flanks and pulled out to a multiple of this length. When stretching the tube of the fold is no longer claimed to train because he lies in the edge of a groove.

For the production of tubes, which consist of two layers, the method is characterized in that after winding the first tube layer, the second layer of tubes is wound in the same manner, the fold of which is offset by at least the width of an exploded groove, and that then grooves or ribs are formed at the location of the folds under formation of the folds in one of the flanks of the forming grooves. In this case, preferably, the grooves or ribs are formed with the folds such that the folds are each on the same sides of the flanks of Ril-len. The tube is in a further embodiment of the invention at the point at which the fold is to be formed on receiving groove, initially wound cylindrical, the corresponding areas are kept free from deformation.

In a tube produced by the method according to the invention, the one or more lying in the flank of the tube groove (s) Verbindungsfalz (e) may be arranged with a slight inclination against the normal plane to the tube axis. The folds can be designed according to a development such that a double undercut (step of the folded edge) is formed. The one or more lying in the flank of the pipe groove (s) Verbindungsfalze (s) are then approximately radially to the tube axis and the folded edge faces the groove bottom.

In the method according to the invention, the fold along the entire longitudinal edges of the pipe wound strip is formed in a special way, so there is no additional work compared to the previously practiced method. The advantages achieved are that such a tube can be optimally compress and pull apart, with all the grooves, u.zw. Even those grooves in which the fold is added, are claimed evenly and in the same way. It is therefore also possible to compress such tubes much more often and pull apart without thereby the fold is overstressed.

The arrangement of the fold in the flank of a groove results in the considerable advantage that this fold on the one hand forms a double undercut (step of the folded edge) and is no longer claimed to train. On the other hand results from the fact that the fold extends approximately in the radial direction, a substantial improvement in the peak compressive strength of the entire Roh4

No. 378924 res, especially in the area of ​​the fold. A tube according to the invention can be laid in a much narrower bending radius than was previously the case with folded tubes, and it can be used for the production of such pipes and thinner sheets and / or foils, because the stress in the region of the fold is substantially reduced or completely disappears. Heretofore, it has been preferred to use thin aluminum foils or sheets for the production of such pipes because the use of other metals has often been associated with certain difficulties in forming and forming the pipe. By the method according to the invention, such difficulties are overcome, so that for pipes according to the invention, films of other metals, u.zw, in particular of stainless steel, are used.

DIN regulations define three different types of pipe types, describing their shape and properties. This definition is based on the hitherto only possible different manufacturing processes and training opportunities such pipes. A tube made in accordance with the invention realizes all the advantages and properties of all three types of tube types.

The fact that the one or more folds are arranged in a tube according to the invention radially to the tube axis, a Nachfedern no longer takes place, so that the bending, compression and pulling apart of the tube without special effort is feasible and the given shape is maintained , Since the peak compressive strength of the tube, especially at the folding of the tube, is significantly improved, such a tube is not only much more resistant to mechanical stress, but it can also be made of a thinner material for this reason.

Since according to the method according to the invention in a simple way, the possibility is given to produce two-ply tubes in which the individual layers are connected independently of each other by the close Verrillung completely secure positive fit together, it is possible to run such pipes much denser than before, because the folds are also in different places, are completely independent of each other and have no connection with each other. In this regard, there have been considerable difficulties in such two-ply pipes. Since in a two-layer pipe according to the invention coated sheet or film strips can be processed without difficulty or even in each case with each strip parallel laid strips of other material wrap, the invention provides the possibility for the production of pipes on the inside and / or outside are provided with a further layer or coated, and in addition to that, they may have another layer or layer between the two layers. A tube according to the invention may thus have several different layers or layers in its wall.

The invention will be explained in more detail below with reference to exemplary embodiments with reference to the drawings. In the drawings, a process variant in each phase is illustrated, u.zw. 2a to 2g for the production of a two-layer pipe, in Figures 3a to 3g for producing a two-layer pipe with an additional outer layer or cover layer, in Figs. 1a to ld for the production of a liner groove tube according to the invention 4a to 4g for producing a two-layer pipe with an additional inner layer or cover layer, and in Figure 5 for producing a two-layer pipe with an additional layer or layer between the two layers.

In all drawings, the winding core is to think above the profile.

According to the invention, initially unwound in the well-known manner of coils strips of thin sheet or foil are grooved in a special device, however, care is taken in the sense of further processing that subsequently to the two edges a smooth area remains. The central portion of this strip, generally designated -1-, is provided with a number of longitudinal grooves -2-. On the one side of the strip, a wider region -3- has remained undeformed, the edge -4- of which is angled approximately at right angles in the direction of the ribs -5- lying between the grooves -2-. On the other side of the strip, a narrow, about half as wide area -6- remained undeformed, with the adjacent edge -7- of the strip is formed as a rib -8-.

Nr.378924

If the strip -1- helically wound on a core arranged above the profile shown in Fig.la profile, u.zw. such that first the winding is wound according to the left side of Fig.la and the winding follows according to the right side of Fig.la, so the formed at the edge -7- of the strip rib -8- sets on the bend - 4-, as shown in Fig.la. As a result, a certain guidance for the strip is achieved even when winding the strip on the core.

At the thus wound on the core strip immediately after the winding process, a fold is generated. For this purpose, according to Fig.lb the rib -8- with the immersing or hooked therein bend -4- in the direction of the wider, undeformed Streifenteils -3-, to which the bend -4- is arranged, folded and after complete flipping , According to the Fig.lc, pressed. It can be seen that, according to FIG. 1c, a connection fold 9 with a simple undercut (folding edge step) has already been formed. Immediately thereafter, in the region of the now assembled and continuous wound strip in which the fold 9 is formed, a further rib -10- is formed on the winding core, as shown in FIG. The shaping of this rib takes place in such a way that the fold 9 is received in one of its flanks 11. This then creates a double undercut seam and a tube that is grooved continuously and uniformly - so that it is no longer immediately apparent that it is a wound from a single sheet metal strip and folded tube.

FIGS. 2a to 2g show, in various steps, the procedure for producing a two-layered tube; Again, there is the core on which the pre-grooved tape is wound to form a tube, each above the profile cross-section shown in the respective Fig. A to g. It will be appreciated that the first steps in making the tube are the same as in the above-described procedure for making a liner tube. According to Fig.2a, a tape is wound on the core, the edges overlap each other with a rib -8- and a bend -4-. Here, the same reference numerals apply mutatis mutandis to the above-described embodiment.

In Fig.2b it is shown that the bend -4- at one edge of the band cross rib -8- is folded to one side, u.zw. to the side of the band, at the edge of the bend -4- is arranged. The rib -8- is gradually compressed, so that initially the two band edges -4 and 7- lie directly on each other and engage behind each other by the corresponding deformation and greater bending or undercut.

After gradually folding the rib -8- under compression then the stage Fig.2c is reached, in which in the surface of the tube immediately outside the winding mandrel, ie in the area of ​​the areas -3 and 6- of the band, a fold -9 - is trained. Already at this stage, another strip -12- is wound onto the tube formed on the mandrel with the strip -1-. This further strip -12- is also pre-grooved with grooves -2'- and ribs -5 '-. The strip -12- has also at the rear edge in the winding direction a bend -4'-, wherein the distance -3'- between the bend -4 '- and the first rib -5'- is substantially smaller than the distance -3 Between the bend -4- and the first rib -5- of the first band -1-.

After further winding up of the tape, the second layer results in the image according to FIG. The opposite edge of the band -12- has laid with its rib -8'- and the free outer edge -7- on the bend -4'-, so that the band is already positively connected at this edge. When placing this next winding of the band -12- outside to the extent already finished tube that forms the inner layer, it is ensured that the wide, undeformed in the groove area -6'- the band -12- the second layer on the fold -9- is formed close fitting. It can be seen from FIGS. 2e and 2f that in the case of the band 12 of the second layer, a fold 9 'is formed in the same way, as was the case with the band 1 of the first layer. Gradually repositioning and compressing the rib -8'-, which overlaps the bend -4'-, creates the fold -9 '-. From Fig.2f it can be seen that the two folds -9 and 9'- in the inner circumferential surface of the tube zwi6

No.378924 see undeformed, not grooved parts of the wound tapes are formed. These are the areas -3 and 6- of the band -1- and the areas -3 'and 6'- of the band -12-. Here, the region -3- is originally as wide as the region -6'-, and the region -6- is originally as wide as the region -3 '-. The width of the regions is matched to one another such that in the final shaping of ribs, corresponding to FIG. 2g, on the winding core, the formed folds -9 and 9'- form the flanks of two successive ribs -10 and 10'-. It is therefore no longer visually recognizable on the tube completed according to FIG. 2g or only with very precise examination that it is a folded tube and where these folds lie. From the above figure is also readily apparent that the aforementioned advantages are given.

In the following figures, pipes produced in the basically same working method as in FIG. 2 are shown, which consist of strips which are provided on one or on both sides with coatings or coatings. According to Fig.3 is used as a second outer band such a band that has a laterally located on its outer coating or support, which is represented by the parallel running dashed line. This coating or overlay may be of any suitable material, it may be in the form of a layer sprayed or otherwise applied to the tape, but it may also be a film applied to or bonded to the tape. The pipe obtained according to Fig.3g is practically a three-layer pipe.

According to the method, which is illustrated with reference to Figure 2, the production of a tube is explained in Figure 4, which also has three layers, but wherein the third layer forms the inner layer and, for example, an insulation of the wall of the tube forms protects this wall against decaying attacks or causes heat or sound insulation. It is used as the first wound on the core tape -1- such a band is used, which is provided on the later inside with a support -14- in the form of a coating with paint, insulating or in the form of an applied or firmly bonded film. The individual steps of the procedure in the manufacture of the tube, according to the representations 4a to 4g, are the same as described in detail under Fig.2. From the representations reproduced here is particularly clear that an additional seal is formed by the third layer -14- also in particular in the fold -9- on the first inner strip, so that an excellent sealed pipe is formed. That was hardly achievable with pipes of this kind so far. In this sense, a tube can be formed in which an inner support or coating is present only in the area of ​​the later fold, in order to obtain a one- or two-layer tube, which is equipped with a special rebate seal.

According to the embodiment of Figure 5, the tape, which serves for the formation of the inner layer of the tube, provided with an outer support. This outer support of the first band may already be applied during the production of the band, as described in the above-described examples in connection with FIGS. 3 and 4. However, the outer layer -15- of the inner band can also be wound up in the stage corresponding to FIG. 5c before another band to be folded is wound onto the core and the band already folded there. The support -15- then forms a second layer in the wall of the tube and overlaps the already completed fold -9-. In the situation -15-, which later forms an intermediate layer between the two folded bands, it may be, for example, a nonwoven made of non-combustible mineral fibers, so that this layer forms a heat and flame insulation. Such a structure of a pipe can be extremely advantageous for example for exhaust pipes of internal combustion engines. Between the two mutually folded layers also several simple wound layers can be arranged, which also have different physical properties.

Nr.378924