WO2000034706A1

WO2000034706A1 - Device for producing a pipe coupling

Info

Publication number: WO2000034706A1
Application number: PCT/EP1999/009445
Authority: WO
Inventors: Harald Selck; Ulrich Griebenow
Original assignee: Selck Gmbh & Co. Kg
Priority date: 1998-12-08
Filing date: 1999-12-03
Publication date: 2000-06-15
Also published as: DE19856523C1; AU1969700A; EP1135641A1

Abstract

The invention relates to a device for producing a coupling of two pipe ends and especially to a coupling which is comprised of a base body and of two press sleeves. By axially displacing the press sleeves, the base body is displaced into the pipe ends in such a manner that a pressure sealed connection is effected. The aim of the invention is to create a metallic pipe connection which is produced by axially pressing press sleeves and which guarantees the highest degree of universality with regard to quality requirements of the pipes to be connected. The device comprises displacement sections inside the press sleeve which interact with displacement elements, said elements being configured on the base body, in such a way that when the press sleeves are pressed on, toothed means which are located inside the base body are radially pressed into the surface of the pipe to be connected.

Description

Device for producing a pipe coupling

The invention relates to a device for producing a coupling of two pipe ends and in particular a coupling which consists of at least one basic body and two compression sleeves, the basic body being displaced into the tube ends by axial displacement of the compression sleeve in such a way that a pressure-tight connection is produced.

Pipe couplings that use this principle are described in US Pat. No. 3,827,727; U.S. Patent 3,893,720; U.S. Patent 4,026,006; U.S. Patent 4,061,367; U.S. Patent 4,482,174; U.S. Patent 5,110,163 known.

The disadvantage of these pipe couplings is that they are limited in their function when used with regard to the size of the pipe diameter, the quality requirements for the pipe to be connected and the level of the pressure of the medium.

To connect two pipe ends, the pipe coupling consists of a cylindrical basic body comprising the two pipe ends to be connected and two compression sleeves, which are each forced over the ends of the basic body.

The basic body is constructed symmetrically for each pipe end, the outer surface having elevations and depressions and these elevations being radially displaced by the press sleeves forced above them.

The inner surface of the basic body has one or more circumferential teeth, which penetrate more or less into the surfaces of the tube ends inserted into the basic body or permanently deform this tube wall due to the radial displacement of the elevations on the outer surface of the basic body as a result of the axial displacement of the compression sleeves.

The technical solution lies in free-standing teeth on the inner surface of the basic body or hidden in recesses. Here the teeth are in different geometric shapes, e.g. B. as a saw tooth, here one side is at right angles to the longitudinal axis of the connection, or as a trapezoidal tooth.

The pipe couplings can be made of different deformable materials, but the press sleeve should consist of a material of the same or higher strength compared to the basic body.

The pipe couplings are usually made of a material that is identical to that of the pipes to be connected.

The invention has for its object to provide a metallic pipe coupling by axially pressing compression sleeves, which ensures the highest degree of universality with regard to the requirements for the quality of the pipes to be connected.

Another object of the invention is to use normal commercial pipes, for example welded pipes according to DIN or the future new European standards and the tolerances with regard to the mechanical properties and length-related dimensions, made of a wide variety of materials, to one that also seals in the high pressure range Lead connection.

Furthermore, it is an object of the invention to minimize the forces required for axially pressing the compression sleeves onto the base body, and thus the force to be applied for penetration into the pipe surface at the maximum penetration depth.

These tasks are solved by a pipe coupling according to the characterizing features of the main claim.

The invention is explained in more detail using an exemplary embodiment. The associated drawings show in Figure 1 is a sectional view through an unpressed pipe connection according to the present invention, in which the pipe ends are inserted into the basic body.

2 shows a sectional view which shows in detail the geometric design of the displacement areas of the basic body in the unpressed state with a press sleeve placed schematically thereon;

3 shows a detail of the entry end of the basic body with the wall thickness a before the axial displacement by the corresponding section of the press sleeve;

4 shows a detail of the section of the basic body with the wall thickness c before the axial displacement by the corresponding section of the press sleeve;

5 shows a detail of the section of the basic body with the wall thickness d before the axial displacement by the corresponding section of the press sleeve;

6 shows a detail of the section of the basic body with the wall thickness e before the axial displacement by the corresponding section of the press sleeve;

7 shows the geometry of the main teeth;

8 shows the geometry of the supporting teeth;

Fig. 9 is a sectional view showing in detail the geometrical design of the displacement areas of the basic body in the veφresstem state;

Fig. 10 is a diagram illustrating the need to use support sleeves depending on the wall thickness and the outer diameter of the pipes to be connected.

11 shows an alternative form of the main teeth for a heavy series of pipe connections. Fig. 12 is a sectional view through an unpressed pipe connection according to the present invention, in which a pressure sleeve is inserted between the base body and the press sleeve, with part of the press sleeve broken away.

The coupling consists of a sleeve-shaped, rotationally symmetrical basic body 1 with axially opposite inlet ends 2, into which the ends of the pipe 4 to be connected are inserted. In relation to axes A-A and B-B, the coupling is constructed symmetrically.

The Grundköφer 1 is made of a material that is identical to that of the pipe 4 to be connected.

The basic body 1 of the coupling begins at its inlet end 2 with a hollow cylindrical section 3, the material thickness a of which is in relation to the outer diameter AD of the tube 4 and the wall thickness s. This section 3 is pressed by the sections 31 and 29 of the press sleeve 25 during the axial pressing onto the base body 1 in a ratio to be defined on the surface of the tube 4 with the aim of compensating for small unevenness in this surface.

Section 3 is followed by a conical widening 5, the rise of which is greater than the rise of the transition section 30 on the press sleeve 25, which displaces this widening 5 radially. The widening 5 merges into a hollow cylindrical section 6, the wall thickness c of which is still to be defined in relation to the outer diameter AD of the tube 4 and the wall thickness s.

Under section 6, the first main tooth 10 runs in a recess 9, the cross section of which forms a triangle with the height h and an angle in the tip of preferably 60 °. This angle enables the force required for the penetration of the main tooth 10 into the surface of the tube 4 to be minimized. For reasons of manufacturing optimization, an angle α of 20 ° to 40 ° is also possible (see Fig. 7).

The widening 5 and the section 6 are during the axial pressing of the compression sleeve 25 onto the base body 1 by the transition section 30 and the displacement section 28 of the Press sleeve 25 is radially displaced, the first main tooth 10 penetrating into the surface of the tube 4, as a result of which the connection is hermetically sealed and the tube 4 is prevented from being pulled out of the coupling.

After section 6 there follows a constriction 11 on the hollow cylindrical section 12, to which a circumferential groove 13 is assigned in the interior 7 of the basic body 1. This groove 13 is delimited at its beginning by the support tooth 14 and at its end by the support tooth 15. The angle in the tip of these support teeth 14 and 15 is preferably 90 °, an angle of 90 ° to 60 ° also being possible for reasons of production optimization (FIG. 8).

When the press sleeve 25 is pressed onto the base body 1, the section 12 with the wall thickness d is displaced by the transition section 30 and the displacement section 28 of the press sleeve 25 in a ratio which is still to be defined, the support teeth 14 and 15 penetrating into the surface of the tube 4. The axial movement of the compression sleeve 25 and the angle of the displaced expansion 5 and constriction 11 are such that a thrust vector via the constriction 11 urges the supporting tooth 14 vertically into the surface of the pipe 4 and at the same time exerts an axial pressure in the direction of the pipe connection, which causes the Material of the tube 4 is slightly planed laterally by the support tooth 14 and the stability of the connection against axial pull-out forces is increased significantly.

Section 12 is followed by a conical widening 16, the rise of which is greater than the rise of the transition section 26 displacing this widening 16 on the press sleeve 25. The widening 16 merges into the hollow-cylindrical section 17, the wall thickness e of which is still to be defined in relation to the outside diameter AD of the tube 4 and its wall thickness s is.

The second main tooth 19, the cross section of which forms a triangle with a height h and an angle in the tip of preferably 60 °, runs under the section 17 in a circumferential recess 18 (FIG. 8). This angle enables the force required for the penetration of the main tooth 19 into the surface of the tube 4 to be minimized. Here, too, angles α (FIG. 7) of 20 ° to 40 ° are possible for reasons of production optimization. O

The widening 16 and the section 17 is radially displaced by the transition section 26 and the displacement section 27 during the axial pressing of the compression sleeve 25 onto the base body 1, the second main tooth 19 penetrating into the surface of the pipe 4, the connection hermetically sealing and the pipe 4 holds in the connection.

The second main tooth 19 is stronger than the first main tooth 10 and has a ratio of 3: 2.

The section 17 is followed by a constriction 20 on the hollow cylindrical section 21, under which there is a groove 22 for forming the support tooth 23. The angle in the tip of the support tooth 23 is preferably 90 °, an angle of 90 ° to 60 ° being possible for reasons of production optimization. When the press sleeve 25 is pressed onto the base body 1, the widening 16, the section 17 and the constriction 20 are displaced by the transition section 26 and the displacement section 27 on the press sleeve 25, as a result of which the support tooth 23 penetrates into the surface of the tube 4. The axial movement of the compression sleeve 25 and the angle of the displaced widening 16 and constriction 20 are such that a thrust vector via the constriction 20 urges the support tooth 23 radially into the surface of the tube 4 and at the same time exerts an axial pressure in the direction of the tube connection, as a result of which Material of the tube 4 is slightly planed laterally by the support tooth 23 and the stability of the connection against pull-out forces is increased significantly.

The section 21 ends at the support flange 24, which limits the path of the compression sleeve 25 during the axial pressing.

The support flange 24 is followed by a groove 32, which is required for the pressing process. Here the pressing tool, not shown, intervenes.

The inside diameter of the basic body 1 corresponds to the outside diameter AD of the tube 4 plus the tolerance possible according to the European standard. This inner diameter is tapered by a shoulder 8 to a diameter which is identical to the inner diameter of the pipe 4 to be connected. This ensures a smooth pipe run. This paragraph 8 limits the length of the pipe 4 to be inserted into the pipe connection. The insertion length 1 of the pipe 4 is in a relation to the outer diameter AD of the pipe 4 that is still to be defined. Fig. 2 shows a side of Grundköφers 1 with non-displaced sections and a schematically overlying press sleeve 25 to represent the areas a, c ^v , d and e of Grundköφers 1 to be displaced when the press sleeve 25 is pressed onto the Grundköφer, which are shown elsewhere be considered even closer.

The press sleeve 25 is a cylinder, the inner contour of which has three graduated cylindrical displacement sections 27, 28 and 29, which are connected to one another via conical transition sections 26, 30 and 31.

When pressing the press sleeve 25 onto the basic body 1, these transition and displacement sections displace the sections of the basic body 1 already explained. The construction is chosen such that the sections of the basic body 1 are displaced one after the other when pressed on. Displacement begins at widening 16 and section 17, then at widening 5 and section 6, and then in section 3.

This time delay enables the forces required for pressing on to be minimized.

11 shows possible alternative forms of the main teeth 10, 19 which are used in the heavy series in the high pressure range.

FIG. 9 shows a cross section through a pipe connection after pressing the compression sleeve 25 onto the base body 1.

By displacing the areas 5-6-11, 12 and 16-17-20, the main teeth 10, 19 and support teeth 14, 15, 23 hidden under these sections with respect to the inner diameter of the basic body 1 are removed from the depressions 9, 13, 18, 22 radially pushed out, which leads to more or less penetration of the teeth into the surface of the tube 4 and permanent deformation of the tube wall.

Since the material of the basic body 1 is identical to that of the pipes 4 to be connected, the depth of penetration of the teeth becomes essentially a) be dependent on the pressure conditions at sections 3, 6, 12 and 17, ie how much material is to be displaced radially in these areas, b) be dependent on the stability of the teeth, ie geometric shape of the tooth and angle at the tip of the Tooth, will be considered in more detail later c) and be dependent on the stability of the tube 4, ie the possible back pressure depending on the outer diameter AD of the tube 4 and its wall thickness s.

If the wall thickness s of the pipe 4 and thus the back pressure is too low, the wall thickness s is reinforced by an additional support sleeve in the area of the pipe connection. This will be discussed later.

The pressure conditions already mentioned are explained in more detail in the further section.

3, the relationship between the section 3 of the basic body 1, the associated sections 29, 31, 28 and the outer diameter AD of the tube 4 is shown. The following relationship applies to this section of the pipe connection:

a = (kaι * AD + ka2) / 2

where: - (10 mm <AD)

- (0.00699 ≤ quay <0.02445)

The following also applies: a = bb = bι - b2

4, the relationship between the sections 5, 6 and 11 of the basic body 1, the associated displacement sections 30, 28 and the outer diameter AD of the tube 4 is shown. In this section, the part c "= c-a of the wall thickness c is radially displaced by the sections 30 and 28 of the press sleeve 25, the first main tooth 4 penetrating into the pipe surface. For c, depending on the outside diameter AD of the pipe 4 to be connected, the following applies:

where: - (10 mm <AD)

- (0.01381 ≤ kci ≤ 0.03127)

5, the relationship between the section 12 of the basic body 1, the associated sections 30, 28 and the outer diameter AD of the tube 4 is shown. In this section, the supporting teeth 14 and 15 run on the inner surface of the basic body 1. By pressing the compression sleeve 25 onto the basic body 1, this section is radially displaced by the amount d ^s = d - a.

For d, depending on the outside diameter AD of the pipe 4 to be connected, the following applies:

where: - (10 mm <AD)

- (0.00079 ≤ kdi ≤ 0.01825)

6, the relationship between the section 16, 17, 20 of the basic body 1, the associated sections 26, 27 and the outer diameter AD of the tube 4 is shown. In this area, the proportion e ^s = e - c is radially displaced from the base body 1 by the sections 26 and 27 of the press sleeve 25, the second main tooth 19 being pushed into the surface of the tube 4.

For e, depending on the outside diameter AD of the pipe 4 to be connected, the following applies:

where: - (10 mm <AD)

- (0.01234 ≤ kei ≤ 0.0298)

In this section, the conical constriction 20 merges into the hollow cylindrical section 21 with the wall thickness f. The thrust vector resulting from the axial movement of the compression sleeve 25 acts on the support tooth 23 via the constriction 20 and urges it into the surface of the tube 4.

For f, depending on the outside diameter AD of the pipe 4 to be connected, the following applies:

f = kfi * AD + kf ₂

where: - (10 mm <AD)

- (l, 3 <kf ₂ ≤ l, 5)

7 shows the geometry of the first main tooth 10 and the second main tooth 19 The angle in the tip is preferably 60 °. The height h is specified for a clear definition of the tooth.

The following applies to the height of the first main tooth 10 hi, depending on the outside diameter AD of the pipe 4 to be connected:

where: - (10 mm <AD)

- (0.01436 ≤ khi ≤ 0.03182)

For the height of the second main tooth 19 112, depending on the outside diameter AD of the pipe 4 to be connected, the following applies:

where: - (10 mm <AD)

- (0.0167 <kh.3 <0.03416)

8 shows the geometry of the support teeth 14, 15 and 23

The teeth are clearly defined with the angle in the tip of the support tooth of 90 ° and the groove depth n. The following applies to the groove depth n, depending on the outside diameter AD of the pipe 4 to be connected:

n = (knι * AD + kn2) / 2

where: - (10 mm <AD)

- (0.00752 ≤ kni ≤ 0.02498)

The ratio of the length 1 of the pipe 4 to be inserted into the pipe connection to the outside diameter AD of the pipe 4 (see FIG. 1)

From this ratio the mechanical stability of the pipe connection with regard to buckling load, e.g. B. if the pipes 4 to be connected meet at an angle different from the design (offset), depending.

Depending on the outside diameter AD, length 1 is recommended, whereby a compromise has been made from a manufacturing point of view:

• for (10 mm <AD <26.9 mm) 1 = -1.2 * AD

• for (28 mm <AD <60.3 mm) 1 = -0.8 * AD

• for (70 mm <AD) 1 = -0.55 * AD

The penetration of the circumferential teeth of the pipe connection into the surfaces of the pipes to be connected and the hermetically sealed connection of two pipe ends thus achieved require a corresponding counter pressure through the pipe to be connected.

The penetration takes place when, in the first phase of the vertical displacement of the teeth into the pipe surface, the pipe can absorb the surface load occurring without deforming. In the further course, there may be permanent deformation of the pipe wall. This surface load to be applied depends essentially on the outside diameter AD, on the wall thickness s, on the modulus of elasticity E and on the width and depth of the impression. The limit range for the required minimum wall thicknesses of the pipes to be connected was calculated according to the requirements of the teaching. If the user of the pipe connection provides thinner-walled pipes, the wall thickness s is supplemented to the required minimum by means of support sleeves in the area of the pipe connection. The selection can be made according to the diagram in Fig. 10.

For safety reasons, the pipe connections should be made with a support sleeve in the border area.

2 shows the geometry of the press sleeve 25. The press sleeve 25, with its conical transition sections 26, 30, 31 and the cylindrical displacement sections 27, 28, 29, displaces section 6 of the basic body by the value c, section 12 by Value d section 17 by the value e "and section 3 by the value a.

For this displacement, the press sleeve 25 with the wall thickness bi is required. This scope is intended to ensure that the press sleeve 25 does not widen to a slight extent when pressed onto the base body 1.

For b, depending on the outside diameter AD of the pipe 4 to be connected, the following applies:

where: - (10 mm <AD)

- (3.5 <kb2 <4.5)

b ₃ = b ₂ - c = b - c + a The invention creates a metallic pipe connection that ensures the highest degree of universality with regard to the requirements for the quality of the pipes to be connected. When using normal, commercially available pipes, for example welded pipes according to DIN or the future new European standards and the permissible tolerances with regard to the mechanical properties and length-related dimensions, made of different materials, this leads to a tight connection even in the high-pressure range.

By optimizing the tooth, the force required to penetrate the pipe surface was minimized at maximum penetration depth.

The solution according to the invention minimizes the forces required for axially pressing the compression sleeve onto the base body, which also enables simple and thus technically feasible constructions of the compression tools even for tube outer diameters> 200 mm. The tube connection is characterized by high stability against vibrations, axial tensile forces on the tube and extreme temperature fluctuations.

The shapes of the main teeth 10, 19 shown in the exemplary embodiments can be further modified without thereby departing from the scope of protection of the patent. For example, it is possible to shorten the main teeth or to flatten or round off the cutting edge. It is also conceivable to dispense with the main teeth completely and to transfer the sealing effect to the supporting teeth.

A special embodiment of the pipe coupling according to the invention takes into account the forces that occur when compressing similar materials, which contribute to an undesired displacement of the material in the axial direction. The use of an additional pressure sleeve 33 between the base body 1 and the press sleeve 25 largely avoids axial displacement of the displacement potential formed on the base body 1 and supports maximum displacement of the potential mentioned and thus the cutting teeth in the radial direction into the lateral surface of the pipe end inserted into the base body 1 4, wherein the pressure sleeve 33 consists of a steel which is harder than the steel from which the basic body 1 and the press sleeve 25 are made.

Although the present invention has been described with reference to a preferred exemplary embodiment, which shows the connection of two pipe ends by the characterizing means of the invention. enabled, it is readily apparent to those skilled in the art that various modifications and changes can be made without departing from the scope of the following claims. It can thus be seen that a pipe connection that only uses the press connection according to the invention on one side, but is equipped on the other side with conventional connecting elements, such as screw connections or flanges, represents a special application of the invention.

Claims

claims

1. Device for producing a pressure-tight coupling of two pipe ends consisting of a sleeve-shaped, rotationally symmetrical basic body with axially opposite inlet ends, the basic body having a substantially cylindrical interior, equipped with toothed means for receiving the pipe ends, and the toothed means by means of on the outer surface of the basic body located elevations pushed compression sleeves are pushed radially into the surface of the pipe ends received, characterized in that

- The respective inlet end (2) of the basic body (1) has a hollow cylindrical section (3), the inner diameter of which allows the outer diameter of the pipe end (4) to be accommodated and its wall thickness a as a function of the diameter AD and the wall thickness s of the pipe to be connected (4) is selectable

- The section (3) merges on its outside via a conical widening (5) into a hollow cylindrical section (6) with a wall thickness c which can be selected as a function of the diameter AD and the wall thickness s of the pipe (4) to be connected, the section ( 6) in the interior (7) of the basic body (1) a circumferential recess (9) for receiving a first main tooth (10) directed against the surface of the tube (4) is assigned,

the section (6) merges via a conical constriction (11) into a hollow cylindrical section (12) with a wall thickness d which can be selected as a function of the diameter AD and the wall thickness s of the pipe (4) to be connected, the section (12) in the interior (7) of the basic body (1) is assigned a circumferential groove (13). which is delimited on both sides by support teeth (14, 15) directed against the surface of the tube (4),

the section (12) merges via a further conical widening (16) into a hollow cylindrical section (17) with a wall thickness e which can be selected as a function of the diameter AD and the wall thickness s of the pipe (4) to be connected, 00/34706 j ₇

wherein the wall thickness e of the section (17) is greater than the wall thickness c of the section (6) and the section (17) in the interior (7) of the basic body (1) has a circumferential recess (18) for receiving a second, against the surface the tube (4) is assigned to the main tooth (19),

- The section (17) passes over a conical constriction (20) into a hollow cylindrical section (21) with a wall thickness f which can be selected as a function of the diameter AD and the wall thickness s of the pipe (4) to be connected, the wall thickness f of the section ( 21) is less than the wall thickness e of the section (17), and the section (21) in the interior (7) of the basic body (1) is assigned a circumferential groove (22) which on the side facing the recess (18) a supporting tooth (23) directed against the surface of the tube (4) is limited,

- The section (21) ends in a support flange (24),

- The press sleeve (25) has an inner region which has cylindrical displacement sections which are connected by conical transition sections, the conical transition section (26) located on the entry side of the press sleeve (25) with the subsequent displacement section (27) resulting from the expansion ( 16), the section (17) and the restriction (20) formed displacement potential is assigned; the transition section (30) adjoining the displacement section (27) with the following displacement section (28) is associated with the displacement potential formed from the widening (5), the section (6) and the constriction (11); and to the transition section (31) adjoining the displacement section (28) with the following displacement section (29) is assigned the displacement potential formed from section (3), the individual displacement potentials being spaced apart from one another in the axial direction such that when the press sleeve () 25) the displacement effect occurs at different times starting with the transition section (26) and the displacement section (27) assigned to the displacement potential.

2. Coupling according to claim 1, characterized in that the increase in the conical widenings (5, 16) in the basic body (1) is greater than the increase in the conical transition sections (26, 30) in the compression sleeve (25).

3. Coupling according to claim 1, characterized in that the wall thickness is a = (kaj * AD + ka ₂ ) / 2, where (10 mm <_ AD), (0.00699 <J aι <0.02445) and ( 0.5 <ka ₂ <0.7) applies.

4. Coupling according to claim 1, characterized in that the wall thickness c = (kcj * AD + kc ₂ ) / 2 + a, where (10 mm <_ AD), (0.01381

<0.03127) and (1.2 <kc ₂ <1.4) applies.

5. Coupling according to claim 1, characterized in that the wall thickness is d = (kdi * AD + kd ₂ ) / 2 + a, where (10 mm <_ AD), (0.00079 <kdj <0.01825) and (0.7 <kd ₂ <0.9) applies.

6. Coupling according to claim 1, characterized in that the wall thickness is e = (kei * AD + ke ₂ ) / 2 + c, where (10 mm <_ AD), (0.01234 <_ke_ <0.0298) and (1.05 <ke ₂ <1.25) applies.

7. Coupling according to claim 1, characterized in that the wall thickness f = (kfj * AD + kf ₂ ), where (10 mm <_ AD), (0.0165

<0.0295) and (1.3 <kf ₂ <1.5) applies.

8. Coupling according to claim 1, characterized in that the main tooth (19) is larger than the main tooth (10), the height of the main tooth (10) hi = (khι * AD + kh2) / 2, wherein (10 mm <AD), (0.01436 ≤ khi <0.03182) and (0.5 <kli2 <0.7), and the height of the main tooth (19) hz = (khs * AD + kh4) / 2, where ( 10 mm <AD), (0.0167 <khs <0.03416) and (1.2 <kh4 <1.4) applies.

9. Coupling according to claim 1, characterized in that the support teeth (14, 15, 23) have a tip angle of 90 ° and the tooth height is defined by the groove depth n, where n = (km * AD + kn2) / 2, where (10 mm <AD),

(0.00752 <kni <0.02498) and (0.2 <kn ₂ <0.3) applies.

10. Coupling according to claim 1, characterized in that the wall thicknesses b _1; b ₂ , b _{3 of} the displacement sections (29, 28, 27) is dependent on the outside diameter AD of the pipe (4) to be connected, where bi = kbi * AD + kb2, where

(10 mm <AD), (0.0999 <kbi <0.1980) and (3.5 <kb2 <4.5) applies and b ₂ = bj - a and b ₃ = b - c = b ₂ - c + a.

11. The device according to claim 1 to 10, characterized in

- That the one inlet end (2) of the basic body (1) has a hollow cylindrical section

(3), the inner diameter of which allows the outer diameter of the associated pipe end (4) to be accommodated and the wall thickness a of which can be selected as a function of the diameter AD and the wall thickness s of the pipe (4) to be connected, this inlet end (2) of the basic body ( 1) has a hollow cylindrical section (3), the inner diameter of which allows the outer diameter of the pipe end (4) to be accommodated and the wall thickness a of which can be selected as a function of the diameter AD and the wall thickness s of the pipe (4) to be connected,

- The section (3) merges on its outside via a conical widening (5) into a hollow cylindrical section (6) with a wall thickness c which can be selected as a function of the diameter AD and the wall thickness s of the pipe (4) to be connected, the section (6 ) in the interior (7) of the basic body (1) a circumferential recess (9) for receiving a first, against the surface of the tube

(4) directed main tooth (10) is assigned,

- The section (6) over a conical constriction (11) into a hollow cylindrical section (12) with a depending on the diameter AD and the wall thickness s of the pipe (4) to be connected selectable wall thickness d, the section (12) in Interior (7) of the basic body (1) has a circumferential groove (13). is arranged, which is delimited on both sides by support teeth (14, 15) directed against the surface of the tube (4),

- The section (12) over a further conical widening (16) into a hollow cylindrical section (17) with a depending on the diameter AD and the wall thickness s of the pipe (4) to be connected wall thickness e passes, the wall thickness e of the section (17) is greater than the wall thickness c of the section (6) and the section (17) in the interior (7) of the basic body (1) has a circumferential recess (18) for receiving a second, directed against the surface of the tube (4) Main tooth (19) is assigned,

- The section (21) ends in a support flange (24),

- The press sleeve (25) has an inner region which has cylindrical displacement sections which are connected by conical transition sections, the conical transition section (26) located on the entry side of the press sleeve (25) with the subsequent displacement section (27) resulting from the expansion ( 16), the section (17) and the restriction (20) formed displacement potential is assigned; the transition section (30) adjoining the displacement section (27) with the following displacement section (28) is associated with the displacement potential formed from the widening (5), the section (6) and the constriction (11); and to the transition section (31) adjoining the displacement section (28) with the following displacement section (29) is assigned the displacement potential formed from section (3), the individual displacement potentials being spaced apart from one another in the axial direction such that when the press sleeve () 25) the displacement effect is delayed starting with the transition section (26) and the displacement section (27) associated displacement potential and

the end opposite the one entry end (2) of the basic body (1) has known pipe connecting elements, or is designed for direct welding of the pipe to be connected.

12. The apparatus according to claim 1, characterized in that between the top formation of the basic body (1) and the inside formation of the press sleeve (25), an intermediate space (34) is provided, in which a pressure sleeve (33) can be used, the pressure sleeve (33) is designed on its inside so that it can be pushed over the sections (6, 17) of the basic body (1) against the stop (35) and on its outside via the sections (5, 6, 11 and 16 , 17, 20) formed displacement potentials of the basic body (1), which are assigned and appropriately designed, and which have an operative relationship with the press sleeve (25) and are formed by the sections (36, 37, 38 and 39, 40, 41) and have primary displacement potentials.