FR2732090A1 - Leakproof pipe connection - Google Patents

Abstract

At least two parts are movable relative to one another in the direction lengthwise of the pipe axis, by increasing the upsetting force until the two tool parts have moved relative to one another in the direction along the pipe axis by a predetermined upsetting distance. A first tool part comprises a first conical pressing face forming part of a bore and whose shape matches the conical bore in the connecting member. A stop face is provided for the end of the pipe with a second tool part comprising a second conical pressing face in the form of a bore and having a cone angle of 90 degrees and the free pipe length is to be subjected to the upsetting operation, and which projects from the smallest diameter of the second conical pressing face towards the stop face.

Description

The invention relates to a tube comprising a connecting section formed at least at one of its two ends by deformation of the end of the tube, this section having two clamping surfaces produced as conical surfaces facing one towards the 'other, the connecting section being intended to be received by its first clamping surface in a conical hole made according to the standard for cutting rings (DIN 3861, May 1994 edition, shape of hole W) for different outside diameters of tube, this conical bore being a component of a connecting body or of a connecting bore of another body, and this conical section being intended to be pressed by its second clamping surface against a conical surface, produced as a bore and having a conical angle of 90, a coupling nut suitable for the connection body or a coupling screw suitable for the connection hole, which can be threaded over the tube.

In addition, the invention relates to a tubular connection and to a method for manufacturing a tube comprising a connecting section.

A tube for a tubular connection, comprising a connecting section formed from the tube material along the contours of a standardized cutting ring, is described in the document DD 240059 A1.

The conical angle of the first clamping surface is however smaller than that of the conical bore of the screw sleeve with which it is associated. Thus we want to make a linear contact of the first clamping surface against the minimum diameter of the conical bore, in order to increase the sealing effect. The second clamping surface cooperating with the coupling nut is compressed, and the conical part starting therefrom and ending forward towards the end of the tube is formed against this end by the first surface of Tightening. The disadvantage here is that due to the high axial screw forces, high surface pressures occur which can lead to packing phenomena which do not meet the high sealing requirements in a lasting manner.

The linear support of the tube in the sleeve also leads, in the event of alternative bending stresses applied via the tube, to settlements and consequently to leaks.

Furthermore, document US Pat. No. 4,871,199 describes a tubular connection and a method for manufacturing the latter in which the conical bore has a conical angle of 30 to 40. The surface of the nut, which cooperates with this drilling, preferably extends at right angles to the longitudinal axis of the nut; however, it can also be realized as a shoulder which extends at an angle of 45 "with respect to the axis. The connecting section of the tube is produced by axial discharge of the latter in a multi-part tool In this case, a deformation takes place so that the tube folds in the region of the connecting section. In this case, the folds must remain accentuated, because during the subsequent assembly, the folds must be deformed further by clamping. These folds are intended to cause elastic compensation, in order to remain tight also in the event of high spikes in internal pressure.

The disadvantage of such an embodiment is that under the internal pressure which occurs, and in particular during the appearance of oscillations, there may be a settlement of the connection, since the elastic stroke is not enough, so that it loses its tightness and must be tightened.

The DIN 2353 standard, June 1991 edition, describes seamless tube screw connections, comprising cutting rings, in which the dimensions for several structural series are determined. The production of the associated coupling nuts is described in standard DIN 3870, edition May 1985, and that of the threaded ends in standard DIN 3853, edition November 1982. The associated cutting rings are defined in standard DIN 3861, edition May 1994 , or the double cone rings in DIN 3865, May 1994 edition.

The coupling nuts or coupling screws and the connection bodies take account of the fact that there remains, also in the tightened state of the connection, a corresponding axial free space between the nut and the connection body to allow tightening. In correspondence, the bicone ring or the cutting ring is made axially longer than this is required by the depth of the holes in the connecting body and the coupling nut.

The underlying objective of the invention is to produce a tube for a tubular connection comprising a connecting section, a tubular connection and a method for manufacturing the connecting section of the tube, which ensure that a tight connection is given. and also maintained during high oscillating pressures and stresses, and that this connection can also be carried out economically.

According to the invention, this objective is achieved by a tube in which the connecting section is produced by pushing back the tube in a tool having at least two partial tools adjustable relative to each other in the direction of the axis. of the tube by increasing the pressing force until reaching a predetermined delivery stroke, the first partial tool of which has a first conical pressing surface produced correspondingly to the conical bore, and as a component of a bore, and a abutment surface for the support of the front surface of the tube, and the second partial tool of which has a second conical pressing surface produced as a bore which has a conical angle of 90 "; where the free length of tube which must be subjected to the discharge operation, by which the tube protrudes beyond the minimum diameter of the second conical pressing surface towards the abutment surface, corresponds to the l length of a bicone ring in accordance with DIN 3865, May 1994 edition, this length resulting from the difference in lengths L3 and Ll for embodiment A, fig. 1, added to the length of the conical bore in accordance with DIN 3861, May 1994 edition, form of bore W, and added to the length of a possibly provided tubular protrusion which is shorter than the cylindrical bore section connecting to the standard tapered bore, plus the length of the discharge stroke which amounts to a minimum of 6 mm and a maximum of 8.5 mm; and where the relative stroke made by the partial tools towards each other in the direction of the axis of the tube during manufacture corresponds to the delivery stroke, and the delivery stroke takes the maximum value when approaching the largest outside diameter used for the tube.

To achieve this objective, the tubular connection according to the invention is characterized by the use of said tube comprising a connecting section of a connecting body, with a conical bore which tapers from the front surface of said connecting body ; in that the minimum diameter of the conical hole is connected to a first hole in the shape of a circular cylinder, which has a shape of hole W according to standard DIN 3861, edition May 1994, and comprises a threaded section arranged on the external surface starting from the first front surface, and comprising a nut capable of being screwed onto the threaded section and comprising a threaded bore adapted to the threaded section of the connecting body; in that a conical surface is connected to the threaded bore and is narrowed in the opposite direction relative to the conical bore of the connecting body; and having a hole through which the tube has passed.

In these embodiments, it is ensured that the connection section is not deformed during assembly or also during repeated assemblies, and that under internal pressures and thus under the oscillating stresses which occur, a loosening of the connection and thus a loss of tightness thereof cannot occur. Here, the connecting section is a component of a screw system, in which the sleeve, the coupling nut and the tube have elastic constants adapted to one another. Neither the assembly forces, nor the forces of stress by pressure pulses and oscillations cause settlement or even loosening of the connection. This achieves secure clamping. The axial clamping force is chosen to be of an order of magnitude such that a secure and tight clamping is maintained, taking into account the maximum operating pressure. In accordance with the requirements of the German industrial standards "DIN", these structural series have been standardized, which are respectively designed for certain maximum admissible operating pressures.

It has been found that the production of a tube comprising a connecting section which ensures secure retention can be achieved by a predetermined delivery stroke of 6 mm to 8.5 mm, the delivery stroke being able to be applied for the entire region. the diameter of the standard structural series. In this case, a deformation is achieved in such a way that no settlement of the connecting section occurs when a mounting or repeated mounting is carried out. In this case, the delivery stroke must be chosen within narrow limits of 2.5 mm depending on the outside diameter of the tube; the discharge stroke increases as the diameter increases. In this case, the material of the tube and the wall thickness are of no importance. They are only important for the pressing force.

When the determined delivery stroke is observed, it is reached that, for the maximum clamping force to be reached during assembly, there is no further axial deformation of the connecting section.

The design of the conical hole in the connection body and the nut with an angle of 24 or 90 "corresponds to the usual design for cutting ring screw connections in accordance with DIN 3861 or 3870. Tolerances for the dimension of the These conical angles also emerge from these standards, thus the tolerance for the conical angle of the conical bore of the connecting body is i 30 min., and for the conical angle of the conical surface of the nut to +20 min.

In a preferred embodiment, provision is made for the conical surface of the nut to be transformed in the bore by means of a curved surface. Thus the cutting stress is reduced.

In addition to the possibility of starting the connecting section directly on the final surface of the tube, it is also possible to provide an arrangement in which a tubular section in the form of a circular cylinder is arranged in front of the first clamping surface which is associated with the conical drilling. This tubular section rests in the mounted state in a circular cylinder-shaped bore of the connecting body, this bore being arranged behind the conical bore.

In this case, it is possible to provide a step between the first clamping surface and the outer surface of the tubular section. The free space formed by the step can be used to receive a joint.

To limit tightening, provision is made for the maximum diameter of the first tightening surface of the connecting section, which is associated with the conical bore, to end in an annular bearing shoulder.

This comes into abutment against the front surface of the connecting body when the maximum tightening is reached.

In concretization of the invention, an improved sealing can be achieved by the fact that there is arranged between the connecting section and / or the tubular sections connecting thereto on both sides, and the associated regions of the connecting body and the nut, a sealing element having a starting state in liquid or pasty form. In addition, it is also possible to further improve the fine sealing by the fact that a seal in the form of a disc is provided between the front surface of the tubular section arranged in front of the first clamping surface and the annular shoulder of the bore of the connecting body. To achieve an improvement in fine sealing, it can also be provided that outside on the connecting section of the tube rests a seal which has a sealing heel clamped between the front surface of the connecting body and the support shoulder of the connecting section.

The method according to the invention for the production of the tube comprising a connecting section which has a first conical clamping surface and a second conical clamping surface extending in the opposite direction to it is characterized in that the tube is clamped in a multi-part tool which has at least the contour in the form of conical pressing surfaces to form the first and second clamping surfaces, with a protrusion of the tube relative to the minimum diameter of the second conical pressing surface towards the abutment surface, where this projection corresponds to the length of a bicone ring conforming to standard DIN 3865, edition May 1994, this length resulting from the difference of the lengths L3 and Ll for embodiment A, fig. 1, added to the length of the conical bore in accordance with DIN 3861, May 1994 edition, form of bore W, and added to the length of a tubular protrusion, possibly to be provided, which is shorter than the connecting cylindrical piercing section with standard tapered drilling, and added with a delivery stroke which amounts to a minimum of 6 mm and a maximum of 8.5 mm, and by the fact that the partial tools are stressed by an increasing pressing force, up to having traveled a relative stroke between the two, which corresponds to the delivery stroke, and a delivery stroke is predetermined which takes the maximum value when approaching the largest outside diameter of the tube used.

For thin-walled tubes, it may be a good idea to press the tube into the hole during deformation.

In developing the method according to the invention, it is proposed to deposit, at least on one of the clamping surfaces of the connecting section and / or at least one of the tubular sections connecting to the two sides of the connecting section, a sealing element in liquid or pasty form, or to associate with the tube to be deformed a sealing element which is deformed with it.

Preferred exemplary embodiments of the tubular connection according to the invention and of a tool, as well as the procedure for producing the deformation of the tube to produce a connection section, are illustrated schematically in the drawings, and they are explained by referring to these.

The figures show: fig. 1 a first embodiment of a tubular connection, where the connecting section of the tube starts directly from a final surface of the tube; fig. 2 an embodiment of the tubular connection, in which a tubular section in the form of a circular cylinder is arranged in front of the connecting section of the tube; fig. 3 an embodiment modified with respect to FIG. 2, comprising a shoulder for delimiting the clamping stroke when the maximum admissible clamping force is reached / exceeded; fig. 4 an embodiment similar to FIG. 3, a seal being placed in the free space between the clamping surface of the connecting section and the conical bore; fig. 5 an embodiment modified with respect to FIG. 4, in which a sealing element in liquid or pasty form has been deposited on partial regions of the connecting section and of the tubular sections connecting thereto; fig. 6 an embodiment in which a sealing disc is placed between the final surface of the tube and the step of the connecting body. 7 an embodiment in longitudinal half-section, comprising a nut having a shortened internal thread and a joint between the connecting body and the nut; fig. 8 an embodiment according to FIG. 3, in which a joint has been placed on the external surface of the connecting section, and next to it a cross section through the annular joint as an individual part; fig. 9 an embodiment with a sealing element placed before the deformation FIG. A tool for producing the tubular connection, namely in the upper half before the deformation of the tube and in the lower half after the deformation of the tube; and fig. 11 a modified embodiment of the tool according to FIG. 9, comprising an additional support of the tube in the bore, also in the upper half before the deformation and in the lower half after the end of the deformation of the tube for the production of the fixing section.

Fig. 1 shows a mounted tubular connection, comprising the connection body 1, the nut 2 screwed onto it and the tube 3 received between the two, using the connection section 4.

From the front surface 5 of the connecting body 1, there is a conical bore 6 which is centered on the longitudinal axis 31 of the tubular connection illustrated in half-section, and which tapers inwards from the front surface 5. The conical bore 6 is transformed at its minimum diameter into a bore 7 in the form of a circular cylinder, which ends with an annular shoulder 8 in the passage bore 9 reduced in diameter for this purpose. A threaded section 10 which extends from the front surface 5 is provided on the external surface of the connection body 1. The conical bore 6 of the connection body 1 has a conical angle
Which is 24. The tolerance range is i 30 min.

The nut 2 screwed onto the connection body 1 has a bore 11 which is provided with a thread 12 which is produced in a manner adapted to the thread 10 of the connection body 1. A conical surface 13 is connected to the bore 11, the l he conical angle is designated by the reference B and amounts to 900 with a tolerance of +20 min. The conical surface 13 extends in the opposite direction to the conical bore 6 of the connecting body 1. The conical surface 13 is transformed in the bore 15 by a curved surface 14. The nut 2 can be provided on the outer surface with key surfaces to be able to tighten it. Similarly, the connecting body 1 can also be provided with a key surface which is connected to the thread 10. When produced as a straight screw, two of the aforementioned connections are provided in the form of holes. conical, which are connected to each other via the passage bore 9 and which are directed in opposite directions to each other. The lengths of the threaded / tapped sections 10, 12 are dimensioned such that during firm tightening, an overlap is achieved with the number of threads which is designed according to the maximum permissible axial clamping force for tightening the connection.

The tube 3 is received by its connecting section 4 between the conical bore 6 and the conical surface 13. The connecting section 4 was developed by forming from the normal diameter of the tube by axial discharge. The connecting section 4 has a first clamping surface 16 which is produced opposite the conical bore 6, and which is in surface contact with the latter. The first conical clamping surface 16 extends directly from the front surface 17 of the tube 3. The first clamping surface 16 ends in a support shoulder 18 which extends radially outward, and which serves to delimit tightening the nut 2 and thus the connecting section 4. The tightening is delimited by the fact that the support shoulder 18 comes to bear against the front surface 5 of the connection body 1.In connection with the shoulder d support 18, a freely located section is formed which turns into a section extending towards the normal wall of the tube 3, and on the outside surface of which is arranged the second clamping surface 19 which is produced as a conical surface and whose conical angle amounts to 90 "Here the tubular section 20 of the tube 3 is connected, which is passed outward through the bore 15 of the nut 2.

In the embodiment of the tubular connection according to FIG. 2, there has been arranged, in front of the first clamping surface 16 of the connecting section 4, a tubular section 21 in the form of a circular cylinder which rests by its outer surface in the bore 7 in the form of a circular cylinder of the connecting body 1 , and whose front surface 1 7a ends before the annular shoulder 8. In this solution also, there is a surface contact between the conical bore 6 and the first clamping surface 16, as well as between the conical surface 13 of the nut 2 and the second clamping surface 19 of the connecting section 4 of the tube 3. However, the connecting section 4 has no abutment surface for the abutment against the front surface 5 of the connecting body 1.

Fig. 3 shows an embodiment which corresponds substantially to that of FIG. 2. A cylindrical tubular section 21 has also been arranged in front of the first clamping surface 16, which is provided with the front surface 1 7a which ends before the annular shoulder 8. In this case, the connecting section 4 is provided with a support shoulder 18 which serves to limit the tightening of the nut 2 and thus of the connecting section 4 relative to the connecting body 1, by the fact that it comes to bear against the front surface 8 of the connecting body 15.

Also in this embodiment, the second clamping surface 19 bears on the surface against the conical surface 13 of the nut 2.

In the embodiment according to FIG. 4, the first clamping surface 16 is made shorter compared to the embodiment according to FIG. 3. The outer surface 22 of the cylindrical tubular section 21 is transformed by a step 23 into the second clamping surface 16, so that between the step 23 and the outer surface 22, and the conical bore 6, a space is formed. free in which esx put in place a seal 24. The second clamping surface 19 is also produced in a conical manner, like the conical surface 13 of the nut 2, and it is in surface contact with the latter. The tube 3 is guided outwards by the tubular section 20 out of the nut 2.

Thanks to the seal 24, the fine sealing of the tubular connection is improved.

This sealing is improved compared to solutions in which the connection between the tube and the connecting body or the nut is carried out by a cutting ring or separate clamping ring, thanks to the absence of intervals.

We see in fig. 5 a modified embodiment with respect to FIG. 4 with regard to fine sealing. Between the first clamping surface 16 resting on the surface in the conical bore 6, and the outer surface 22 of the cylindrical tubular section 21 arranged in front, a sealing element is provided which is deposited in pasty or liquid form on these surfaces. The resulting seal is designated by reference 24a. Similarly, there is provided between the tubular section 20 of the tube 3, which is guided out of the nut 2, and the bore 15 of the nut, a seal 24a which is deposited in pasty or liquid form on the outer surface of the tube 3.

Fig. 6 shows an arrangement in which the tube 3 is clamped by the connecting section 4 between the connecting body 1 and the nut 2, and whose tubular section 21 resting in the bore 7 of the connecting body 1, is supported by its front surface 17a against a seal 24b in the form of a flat ring which bears by its other face against the annular shoulder 8 of the bore 7.

Fig. 7 shows another variant of the tubular connection, in which the threads of the connection body 1 and of the nut are produced in a shortened manner and, in the tightened state, overlap only over a length which is dimensioned according to the maximum permissible axial clamping force. In addition, the nut 2 has in its bore a surface 41 extending radially relative to the longitudinal axis 31. Between this surface 41 and the front surface 5 of the connecting body 1, is tightened a seal 24c which seals the slot between the connecting body 1, the connecting section 4 of the tube 3, and the nut 2.

Fig. 8 shows another embodiment of the seal, in which a seal 24d has been placed on the outer face of the connection section 4 of the tube 3. This has, as seen in particular in the illustration of the seal 24d as an individual part, an annular sealing heel 42 directed radially inwards, which is tightened, in the tight state of the tubular connection , between the front surface 5 of the connection body 1 and the radial support shoulder 18 of the connection section 4 of the tube 3.

Fig. 9 shows another modified embodiment of the seal, in which there is arranged, between the conical bore of the connection body 1 and the first conical clamping surface of the connection section, a seal 43 which has been associated with the tube 3 before deformation, and that has been distorted with this one.

The shape of the connecting section 4 according to FIGS. 1 to 9 developed by pushing back the full tube into a tool as illustrated for example in FIG. 10. The upper half illustrates the mutual association of the sleeve 26 in one piece with the clamping jaw 32 assembled in several parts before the deformation of the tube 36. In the position illustrated below the longitudinal axis 31, the sleeve 26 and the clamping jaw 32 is in a close position, that is to say introduced, the connecting section 4 being illustrated in a shaped manner. The sleeve 26 comprises a heel 27 projecting from one side. Starting from the front surface 30 of the heel 27, a first pressing surface 28 is provided which taper tapering and which turns into a blind perch. 29 in the form of a circular cylinder which ends in the bottom surface 29a. The sleeve 26 can be moved by a force drive, for example a hydraulic cylinder, in the direction of the clamping jaw 32 along the longitudinal axis 31. The clamping jaw 32 is constituted for example in two halves 32a , 32b, and radially wedges the tube 36 by the clamping hole 35 so that it is retained without being able to be moved axially. The clamping jaw 32 has a hole 33 which has a dimension larger than the outside diameter of the heel 27 of the sleeve 26, so that this sleeve can plunge into the hole 33. The hole 33 turns into a second conical pressing surface 34 which narrows in the opposite direction to the direction of narrowing of the conical pressing surface 28 of the sleeve 26; this pressing surface 34 ends with its minimum diameter Da in the clamping bore 35 which bears against the external surface of the tube 36. For this purpose, the clamping bore 35 can be provided for example with elements which increase the coefficient of friction, and it can bite into the surface of the tube 36.

In fig. 10, in the upper half, the tube 36 is retained by the two clamping jaws 32a, 32b radially - and thus axially tightened. The penetration length of the tube 36 or the length by which it protrudes axially towards the sleeve 26 beyond the clamping jaws 32 is predetermined. The length L consists of the sum of the lengths of a standardized bicone ring, which results from the difference of the lengths L3 and L, for embodiment A, fig. 1, according to DIN 3865, May 1994 edition, added to the length of the tapered hole resulting from DIN 3861, May 1994 edition, hole shape W, as well as the length of a protrusion (length Y) possibly provided which is shorter than the cylindrical drilling section connecting to the standard tapered drilling, and the length of the delivery stroke X which is chosen between 6 mm and 8.5 mm depending on the outside diameter of the tube. consequently calculates respectively for a tube having an outside diameter of 10 mm or 38 mm, for the structural series S or
L and without protruding from the tube (Y = 0), as follows:
type L3 L1 Lcone YXL
10 L 26 20 5.41 0 7 18.41
38 S 48.5 39.5 6.35 0 8.5 23.85
The tube 36 is supported by its front surface 37 against the bottom 29a of the blind bore 29. By displacement of the sleeve 26 to the right of the delivery stroke from 6 mm to 8.5 mm, the wall of the tube 36 bulges towards the outside, and it rests against the conical pressing surface 28 of the sleeve 26 or against the conical pressing surface 34 of the clamping jaw 32. In this case, a discharge of a surface of stop towards the front surface 30 of the sleeve 27. The pressing force P by which the sleeve 26 deforms the tube 36 is increased so far until the predetermined delivery stroke, i.e. the relative axial travel traveled by the sleeve 26 relative to the clamping jaw 32, is reached, the clamping surfaces forming in the desired manner.

In this case, the pressing force P necessary for this purpose exceeds the tightening force S which is established when the nut is tightened by the predetermined tightening stroke, taking into account the screw pitch.

In producing the tool according to FIG. 11, a bearing pin 40 which protrudes from the bottom 29a beyond the front surface 30 of the heel 27 axially in the direction of the tube 36 has been formed on the sleeve 26 centrally with respect to the axis 31. plunges into its bore 39 for support. Such support can be advantageous in particular for thin-walled tubes.

Claims (15)

Claims 1. Tube (3) comprising a connecting section (4) arranged at least at one of its two ends by deformation of the end of the tube, this section having two clamping surfaces (16, 19) produced as conical surfaces and directed towards each other, the connecting section (4) being intended to be received by its first clamping surface (16) in a conical bore (6) produced according to the standard for cutting rings (DIN 3861, May 1994 edition, drilling form W) for different external tube diameters, this conical drilling being a component of a connecting body (1) or a connecting drilling of another body, and this conical section being intended to be supported by its second clamping surface (19) against a conical surface (13), produced as a bore and having a conical angle of 900, with a coupling nut (2) adapted to the connecting body (1 ) or a coupling screw suitable for the connection hole, which can be threaded over the tube (3), characterized in that the connecting section (4) is produced by pushing back the tube (3) in a tool having at least two adjustable partial tools (26, 32) relative to each other in the direction of the axis of the tube (31) by increasing the pressing force (P) until reaching a predetermined delivery stroke (X), including the first partial tool (26) has a first conical pressing surface (28), which is produced correspondingly to the conical bore (6) and as a component of a bore, and a stop surface (29a) for supporting the front surface ( 37) of the tube (3), and the second partial tool (32) of which has a second conical pressing surface (34) produced as a bore which has a conical angle of 90, in which the free length of tube (L) which must be subjected to the discharge operation, whereby the tube protrudes beyond the minimum diameter (D) from the second conical pressing surface (34) towards the abutment surface (29a), corresponds to the length of a bicone ring conforming to standard DIN 3865, May 1994 edition, this length resulting from the difference in lengths L3 and L , for embodiment A, fig. 1, plus the length of the conical hole in accordance with DIN 3861, May 1994 edition, shape of hole W, and plus the length of any tubular protrusion (length Y) which is shorter than the length of the hole cylindrical connecting to the standard conical bore, and adding the length of the delivery stroke (length X) which amounts to a minimum of 6 mm and a maximum of 8.5 mm, and in that the relative stroke made by the partial tools (26, 32) in relation to each other in the direction of the axis of the tube (31) during manufacture, corresponds to the delivery stroke (X), and the delivery stroke (x) taking the maximum value by approaching the largest outside diameter of tube used. 2. Tube according to claim 1, characterized in that there is provided a tubular section (21) in the form of a circular cylinder in front of the first clamping surface (16) of the connecting section (4) associated with the conical bore ( 6). 3. Tube according to claim 2, characterized in that there is provided a step (23) between the first clamping surface (16) and the outer surface (22) of the tubular section (21). 4. Tube according to claim 2, characterized in that there is provided a seal (24) arranged in the free space formed by the step (23). 5. Tube according to claim 1, characterized in that the maximum diameter of the first clamping surface (16) of the connecting section (4) ends in an annular bearing shoulder (18). 6. Tubular connection, comprising a tube (3) which has a connection section (4) according to the features of claim 1, comprising a connection body (1) with a conical bore (6) which tapers from the front surface (5) of said connecting body; to the minimum diameter of the conical bore (6) is connected a first bore (7) in the form of a circular cylinder, which has a form of bore W according to standard DIN 3861, edition May 1994, and comprising a threaded section (10) arranged on the outer surface starting from the first front surface (5), and comprising a nut (2) capable of being screwed onto the threaded section (10), and comprising a tapped hole (11) adapted to the threaded section (10) of the body connection (1); a conical surface (13) is connected to the tapped hole and tapers in the opposite direction relative to the conical hole (6) of the connecting body (1), and with a hole (15) through which the tube ( 3, 3a). 7. Tubular connection according to claim 6, characterized in that the conical surface (13) of the nut (2) is transformed in the bore (15) by a curved surface (14). 8. Tubular connection according to either of claims 6 and 7, characterized in that it is arranged between the connecting section (4) and / or the tubular sections (20, 21) connecting thereto two sides, and the associated regions of the connecting body (1) and the nut (2), a sealing element (24a) having a starting state in liquid or pasty form. 9. Tubular connection according to any one of claims 6 to 8, characterized in that there is provided a disc-shaped seal (24b) arranged between the front surface (17a) of the tubular section (21) arranged in front of the first clamping surface (16), and the annular shoulder (8) of the bore (7) of the connecting body (1). 10. Tubular connection according to any one of claims 6 to 9, characterized in that outside on the connecting section (4) of the tube (3), rests a seal (24d) which has a heel of seal (42) clamped between the front surface (5) of the connection body (1) and the bearing shoulder (18) of the connection section (4). 11. Tubular connection according to any one of claims 6 to 10, characterized in that a seal (24c) is arranged between the front surface (5) of the connection body (1) and a surface (41) extending radially in the bore of the nut (2). 12. Method for manufacturing a tube comprising a connecting section which has a first conical clamping surface (16) and a second conical clamping surface (19) extending in the opposite direction thereto in particular for a tubular connection according to any one of claims 6 to 11, characterized in that the tube (3) is clamped in a tool (26, 32) in several parts which has at least the contour in the form of conical pressing surfaces (28 , 34) to form the first and the second clamping surface (16, 19), with a projection of the tube (3) with respect to the minimum diameter (D) of the second conical pressing surface (34) towards the abutment surface (29a), where this protrusion corresponds to the length of a bicone ring conforming to standard DIN 3865, May 1994 edition, this length resulting from the difference in lengths L3 and L, for embodiment A, fig. 1, added to the length of the conical bore in accordance with DIN 3861, May 1994 edition, form of bore W, and added to the length of a tubular protrusion (Y) possibly provided which is shorter than the cylindrical drill section connecting to the standard conical bore, and adding the length of a delivery stroke which amounts to a minimum of 6 mm and a maximum of 8.5 mm, and in that the partial tools (26, 32) are stressed by an increasing pressing force (P), until having traveled a relative stroke between the two, which corresponds to the delivery stroke (X), where a delivery stroke (X) is predetermined which takes the maximum value in s approaching the largest tube outside diameter used. 13. Method according to claim 12, characterized in that the tube (3, 3a) is pressed in its bore during the deformation by the pressing force (P). 14. Method according to claim 12, characterized in that one deposits, on at least one of the clamping surfaces (16, 19) of the connecting section (4) and / or at least one of the tubular sections (20, 21) connecting its two sides of the connecting section (4), a sealing element (24a) in liquid or pasty form. 15. Method according to any one of claims 12 to 14, characterized in that before the deformation, is associated with the tube to be deformed (3) a sealing element which is also deformed therewith.