EP2535124A1 - Mechanical pipe expander - Google Patents

Abstract

The expander (1) has a tool drive (12) converting a relative axial movement into a radial movement between a drawbar (2) and a counter bearing (4). The tool drive is axially fixed with the drawbar by a clamping element (21). The clamping element is designed as a mechanically strained clamping element, which comprises an axially acting tensioning element (29) for producing mechanical tension. Tensile force is transmitted to an intermediate ring (31), a lubricant ring (32) and the tool drive in a pulling direction (3) over the clamping element.

Description

The invention relates to a mechanical Zugxpander for pipes with a pull rod, with at least one Expanderwerkzeug, which exerts a radial expansion force on the tube by means of a radial movement, with a counter-bearing and with a tool drive, which axial relative movement between the tie rod and the anvil in a radial movement that drives the expander tool radially, and which is axially fixed to the tie rod by means of a clamping element, wherein the clamping element transmits a tensile force acting in a pulling direction of the tie rod by means of a radially applied to the tie rod clamping force on the tool drive

The DE 22 58 359 A1 For example, a similar mechanical tensile expander or a mechanical tube expander is treated with a clamping element which transmits the tensile force applied by the drawbar to the tool drive. In this case, however, the clamping force of the clamping element is not radially but axially to the drawbar by means of a thread on the tie rod, in which engages a corresponding thread of a nut of the clamping element transmitted. The high forces acting on the clamping element or on the nut of the clamping element tensile forces can lead to thread breaks, which are caused by notch effect, and consequently to failures of this Zugxpanders.

To avoid the damage caused by the notch damage to the drawbar, suggests the DE 29 06 693 C2 a clamping element with a radially applied to the pull rod clamping force. The disclosed clamping element, which is also known in the art as Druckölverband, is applied for mounting between an inner ring and an outer ring of the clamping element with pressure oil, which forms a gap between the inner ring and the outer ring and the two rings can be pushed into each other. After releasing the pressure between both rings a press fit, which causes a radial clamping force on the pull rod. In practice, however, has shown that on the one hand very high pressures are required and on the other hand, a used oil pump must be located outside the Zugxpanders and thus very long and twisted pipes must be laid to the clamping element through the pipe to be expanded through. In addition, it has been found that such a pressure oil dressing does not meet the expected requirements in terms of reliability and clamping force.

It is therefore an object of the invention to provide a Zugxpander with a clamping element available, which can be easily mounted as well as a permanently operated.

To achieve the object, a mechanical Zugxpander for pipes with a pull rod, with at least one Expanderwerkzeug, which exerts a radial expansion force by means of a radial expansion force on the pipe, with a counter-bearing and with a tool drive proposed which axial relative movement between the tie rod and the counter bearing converts into a radial movement, which drives the expander tool radially, and which is axially fixed to the tie rod by means of a clamping element, wherein the clamping element transmits a tensile force acting in a pulling direction of the tie rod by means of a radially applied to the tie rod clamping force on the tool drive and wherein the Zugxpander characterized in that the clamping element is a mechanically driven clamping element.

The mechanically driven and thus mechanically strained and radially effective clamping element offers over the solution according to the DE 29 06 693 C2 the advantage that on the one hand a simple installation and a simple clamping of the clamping element is possible because it can be dispensed with additional hydraulic assemblies, and on the other hand because of the omission of other modules of the expander robust and can be used with a higher reliability, because additional sources of error reduced can be. Furthermore, a mechanically clamped and radially effective clamping element offers the possibility of the advantages of the solution after DE 29 06 693 C2 to use and to transfer tensile forces from the drawbar without the formation of a notch effect on the drawbar on the tool drive.

In particular, the advantages mentioned above come into play, when the clamping element has an inner ring with an outer inner ring clamping surface and an axial to Inner ring displaceable outer ring having a complementary to the outer inner ring clamping surface inner outer ring clamping surface. In addition, the clamping element with inner ring and outer ring has the advantage that the clamping force can be applied with particularly simple means.

Thus, between the inner ring and the outer ring acting radially on the tie rod clamping force can be formed particularly advantageous if the two rings against each other inclined clamping surfaces and these clamping surfaces apply the radial clamping force by an axial clamping of the two rings. Consequently, it is for a Zugxpander with clamping element having an inner ring and an outer ring, in particular advantageous if the outer inner ring clamping surface and the inner outer ring clamping surface at least partially correspond to a conical surface. The mutually complementary conical surface areas, which may alternatively be pyramid shell surfaces, are thus able to be used as wedges or ramps to transform the axial clamping force into a radially acting clamping force.

In connection with an inner ring and with an outer ring, it is also advantageous if the outer ring has a greater wall thickness than the inner ring, which may result in that the outer ring is less subject to elastic stretching due to the applied clamping force than the inner ring and thus by means the greater elastic deformation of the inner ring, the resulting clamping force can be applied to the pull rod effectively. Very generally, it is accordingly advantageous if the outer ring is stiffer than the inner ring, so that this arrangement is already inherently rigid enough to deploy accordingly large clamping forces radially inward. By means of a correspondingly thicker wall thickness, sufficient inherent rigidity of the outer ring can be easily provided. On the other hand, this can also be implemented by a suitable choice of material or by other measures.

For a Zugxpander with clamping element, which has an inner ring and an outer ring, it is also particularly advantageous if a clamping angle of the clamping element and a drive angle of the tool drive with respect to a pulling direction of the tie rod have the same sign.

In this case, the term "clamping angle" is understood to mean the angle which the outer inner ring clamping surface or the inner outer annular clamping surface complementary thereto encloses with respect to the pulling direction or to an axis of symmetry of the pull rod which is axially connected to the drawbar. As such, the term "drive angle" refers to that angle which is enclosed by said axis of the drawbar and an outer surface of the tool drive which is complementary to an inner surface of the expander tool. In this respect, the mode of operation between the tool drive and the expander tool corresponds to that which exists between the inner ring and the outer ring, as explained above.

In particular, a similar sign for the clamping angle of the clamping element and the drive angle of the tool drive with respect to a pulling direction of the drawbar - both angles are referenced to the same coordinate system - benefits due to the same effective direction of the clamping force and the force of Expanderwerkzeuges when on the drawbar the tensile force is applied.

In a particularly advantageous embodiment of the expander of the clamping angle relative to the drive angle on a smaller or equal amount, which has the advantageous consequence that - if the friction conditions are identical - the clamping force acting on the clamping element is always greater than acting on the Expanderwerkzeug Force. As can be seen immediately, a release of the clamping element is reliably avoided by this embodiment. It is immediately apparent that at different friction conditions, for example by lubricant between the tool drive and expander tool, the angle can be quite different.

Alternatively, a clamping angle of the clamping element and a drive angle of the tool drive with respect to a pulling direction of the pull rod opposite sign have, which constructively brings relief, since the angle does not need to be coordinated so precisely to avoid failures reliably.

Also, in order to solve the problem mentioned above, a mechanical Zugxpander for pipes with a pull rod, with at least one Expanderwerkzeug, which exerts a radial expansion force on the tube by means of a radial movement, proposed with an abutment and with a tool drive, which axial Relative movement between the drawbar and the anvil converts into a radial movement which drives the expander tool radially, and which is axially fixed to the pull rod by means of a clamping element, wherein the clamping element acting in a pulling direction of the drawbar pulling force by means of a radially applied to the drawbar clamping force on the tool drive transmits and wherein the Zugxpander characterized in that the tensile force is transmitted in the pulling direction on the clamping element on an intermediate ring and then on the tool drive.

By such an intermediate ring on the one hand a simple assembly and a simple clamping of the clamping element is possible because arranged behind the intermediate ring, so arranged on the side facing away from the clamping element, assemblies through the intermediate ring of any local stresses that could be caused by the clamping element through the intermediate ring can be relieved.

Preferably, the intermediate ring projects beyond at least one axially before or behind it to the abutment arranged radially outwardly projecting assembly radial, so that this assembly during operation and in particular during insertion of Expanderwerkzeugs in a pipe or when transferring a pipe through the expander through the intermediate ring, for example, against an abutment against the pipe or against mechanical contact with third components or objects, can be protected. This relates, depending on the specific configuration of the mechanical Zugxpanders, in particular, for example, the outer ring, the expander tool in the retracted state, the tool drive and / or a lubricant ring or any hydraulic lines or any on the lubricant ring (32) arranged hydraulic assemblies.

Likewise, in order to achieve the object mentioned, a mechanical Zugxpander for pipes with a pull rod, with at least one Expanderwerkzeug, which exerts a radial expansion force on the tube by means of a radial movement, proposed with an abutment and with a tool drive, which axial Relative movement between the tie rod and the anvil converts into a radial movement which drives the expander tool radially, and which is axially fixed to the tie rod by means of a clamping element, wherein the clamping element acting in a pulling direction of the tie rod Pulling force by means of a radially applied to the pull rod clamping force on the tool drive transmits and wherein the Zugxpander characterized in that the tensile force is transmitted in the pulling direction on the clamping element on a lubricant ring and then on the tool drive.

By such a lubricant ring, although this represents an additional assembly, on the one hand a simple assembly and a simple clamping of the clamping element possible, since any delay in the clamping element, in particular in the solution after the DE 29 06 693 A1 can also occur in the areas acted upon with oil in the lubricant ring is not or only to a much lesser extent to be feared. In particular, as a result, the hydraulic areas can then be largely relieved of such a delay. Accordingly, the oil supply is less affected by a careless bracing.

Preferably, the intermediate ring is pierced by at least one hydraulic line, so that the intermediate ring can protect the hydraulic line accordingly. It is understood that such a hydraulic line can lead to the lubricant ring, for example, but also to other assemblies that must or must be supplied with oil or lubricant and / or hydraulic pressure.

A further advantageous embodiment of the Zugxpanders is made possible when an inner inner ring clamping surface of the clamping element and a Zugstangenklemmfläche the drawbar are cylindrical. This embodiment of the contact surface between clamping element and tie rod particularly advantageously prevents the occurrence of a notch effect, which preferably occurs with cross-sectional jumps and consequently can be reduced to a minimum when using a cylindrical surface. A notch-free surface transition thus provides for the reduction of voltage spikes and on the one hand enables higher loads to be transmitted or on the other hand to increase the service life or the reliability of the expander.

For a simple application of the clamping force, it is also advantageous if the clamping element for mechanical clamping at least one axially effective clamping element, which is preferably itself formed mechanically. Furthermore, in order to achieve a particularly uniform introduction of the clamping force, it is advantageous if the clamping element Having radially circumferentially arranged clamping elements. For example, radially encircling and axially aligned with the inner ring of the clamping element screws can be arranged, which engage through the inner ring into the outer ring and tighten by tightening the inner ring with the outer ring. Although an annular arrangement of a plurality of clamping elements appears to be expensive to operate, since each individual clamping element has to be actuated individually. On the other hand, this relatively large forces can be applied with easy to operate and sufficiently stable trainees clamping elements. Alternatively, for example, but also a single axially acting clamping nut for clamping the clamping element or for bracing the inner and outer ring can be used. Regularly, such a single clamping nut will be a custom-made item, which is correspondingly expensive to provide. The axial alignment of the clamping elements is not absolutely necessary per se, but has the advantage that the clamping elements can be effective directly between the inner and outer ring and are also relatively easy to access.

As can be seen immediately is not only a use of screws necessary. It can also be used to apply a clamping force bolts, rivets, tie rods or clamps.

Lastly, it is also advantageous for a pull expander if the clamping element comprises at least one annular spring clamping element and / or a conical surface clamping element. In this respect, there is the possibility to resort to standardized and mass-produced and therefore cost-produced machine elements, which have proven themselves many times and thus can particularly increase the reliability. In this case, it may prove necessary to provide a hub in order to be able to counteract the clamping forces to a sufficient extent radially, since in general ring spring or a conical surface clamping elements are constructed symmetrically, so that sufficient, radially inwardly acting forces only by an outer hub, which counteracts radially outward forces and prevents the outer ring to escape radially outward, can be applied.

Figur 1

eine Anordnung aus Zugstange, Klemmelement, Werkzeugtrieb und Expanderwerkzeug eines mechanischen Zugexpanders;

Figur 2

eine schematische Detaildarstellung eines Zugexpanders mit einer herkömmlichen Klemmeinrichtung in eingefahrenem Zustand;

Figur 3

den Zugexpander nach Figur 2 in expandierendem Zustand; und

Figur 4

eine alternative Anordnung aus Zugstange, Klemmelement, Werkzeugtrieb und Expanderwerkzeug eines mechanischen Zugexpanders in ähnlicher Darstellung wie Figur 1.

Further advantages, objects and characteristics of the present invention will be explained with reference to the following description of the appended drawings. In the drawing show:

FIG. 1

an arrangement of pull rod, clamping element, tool drive and expander tool of a mechanical Zugxpanders;

FIG. 2

a schematic detail of a Zugxpanders with a conventional clamping device in the retracted state;

FIG. 3

the train expander after FIG. 2 in an expanding state; and

FIG. 4

an alternative arrangement of drawbar, clamping element, tool drive and expander tool of a mechanical expander in a similar representation as FIG. 1 ,

On a pull rod 2 a Zugxpanders 1 after FIG. 1 , which has a cylindrical surface throughout, a clamping element 21 is attached, whereby a force applied by the pull rod 2 in a pulling direction 3 tensile force is transmitted to a tool drive 12. The cylindrical surface of the tie rod 2 forms a Zugstangenklemmfläche 25 at the level of the clamping element 21. On this Zugstangenklemmfläche 25, the clamping element 21 is clamped by an inner ring 22 of the clamping element 21 in the axial direction, ie in the pulling direction 3, clamped with an outer ring 26 of the clamping element 21 is. The axial clamping force, which is applied via clamping elements 29, screws in this embodiment, is transformed by means of a clamping angle 28 between the inner ring 22 and the outer ring 26 in a radial clamping force.

To produce the clamping force an outer inner ring clamping surface 23 of the inner ring 22 and an outer ring clamping surface 27 of the outer ring 26, which are each inclined with the clamping bracket 28 against the pull rod 2, together. The tensile force in the pulling direction 3 is finally transmitted via the non-positively connected surfaces, the Zugstangenklemmfläche 25 and an inner inner ring clamping surface 24 of the inner ring 22, an intermediate ring 31 and a lubricant ring 32 and then to the tool drive 12.

The tool drive 12, which adjoins the lubricant ring 32 and which is supplied with lubricant via the lubricant ring 32, drives an expander tool 11 via an inner driving ramp 13, which includes an angle of rotation 15 with the drawbar 2 or an axis of symmetry of the drawbar 2. Together with an external driving ramp 14 of the expander tool 11, the tool drive 12 converts the axial pulling movement of the drawbar 2 in the pulling direction 3 into a radial movement of the expander tool 11. To support and to support the tensile force transformation, the expander tool 11 abuts against an abutment 4, which is pierced by the pull rod and against which the pull rod 2 is arranged relatively movable.

The in FIGS. 2 and 3 illustrated and essentially for explaining the further operation of the arrangement also after FIG. 1 Traction expander 1 described here has a clamping element 21 designed as a clamping nut according to the prior art and is shown by way of example in retracted and in an expanding state.

Both in the embodiment according to FIG. 1 as well as in the example FIGS. 2 and 3 expander tool 11 and tool drive 12 perpendicular to the drive ramps 13, 14 positively connected to each other, so that the tool drive 12 can also transmit a tensile force on the Expanderwerkzeug and nevertheless a sliding movement of Expanderwerkzeug 11 and tool drive 12 along the drive ramps 13, 14 is possible. The anvil 4, against which the axial tensile force is supported, has in the FIGS. 2 and 3 shown Zugxpander 1, as well as in the embodiment according to FIG. 1 , via additional anchor 5 (in FIG. 1 not shown), which fix the expander tools 11 in the pulling direction 3. The fixation serves to retract the expander tools 11 during retraction of the drawbar 2 and consequently to create a gap between the expander tool 11 and the pipe so that the draw expander 1 can be approached unhindered to the next position of the pipe in which a corresponding expansion process is to take place.

Also, the clamping element 21 of the expander 1 after FIGS. 2 and 3 and the tool drive 12 via screws (not numbered) connected to each other, so that when moving back the drawbar 2, a corresponding relative movement between the tool drive 12 and thrust bearing 4 can be ensured by which the expander tools 11 can be safely retracted.

It is understood that instead of the aforementioned and unspecified figured screws and / or instead of the armature 5, other compounds may be provided which are sufficiently strong to allow such a return stroke and the Expander tools 11 suitable retract. In any case, the forces occurring here are significantly lower than in the expansion process.

Also the arrangement after FIG. 1 has at the abutment 4 a corresponding and equal effective anchor and corresponding connections between the clamping element 21 of the expander 1 after FIG. 1 , the intermediate ring 21, the lubricant ring 32 and the tool drive 12 (in each case in FIG. 1 not explicitly shown), in which case the corresponding screw connection preferably does not include the inner ring 22 of the clamping element 21 and attaches only to the outer ring 26 with respect to the clamping element 21. In an alternative embodiment, for example, the clamping elements 29 can be used accordingly for this connection, so that the inner ring 22 of the clamping member 21 is connected accordingly.

It is understood that the return stroke can be ensured in alternative embodiments by other suitable measures, as long as a corresponding countermovement of the expander tools 11 is achieved, with a induced by the pull rod 2 return stroke is advantageous because no additional drives are provided and only one implementation the return movement of the drawbar 2 in a return stroke of the expander tools 11 needs to be ensured.

The designed as a clamping nut according to the prior art clamping element 21 of the expander 1 after FIGS. 2 and 3 also transfers the tensile force acting in the pulling direction 3 by a clamping force acting axially on the pull rod 2, like the clamping element 21 of the draw expander 1 FIG. 1 by a radially corresponding to claim 1 acting on the tie rod 2 clamping force.

A traction unit of the Zugxpanders 1 for applying the tensile force on the drawbar 2 has, as is already known from the prior art, via a pull cylinder 41 and a tension piston 42 as from the FIGS. 2 and 3 can be seen and comes in the course expander 1 FIGS. 1 to 3 according to the application.

Here, the tension piston 42 is operatively connected to the pull rod 2, wherein the axial connection between the tension piston 42 and the pull rod 2 on the tool drive 12th turned away side on the trained as a single screw clamping element 21. In this a fixing nut (not shown) is provided, which the axial connection in the Zugxpander 1 after FIGS. 2 and 3 between clamping element 21 and the tool drive 12 creates, which has already been described above for the return stroke. A similar fixing nut is also in the course expander 1 after FIG. 1 intended. Instead of such a fixing nut, a corresponding other possibility, also to transmit compressive forces for a return stroke, may be provided.

Between the tension cylinder 41 and the tension piston 42 are each two chambers, a tension chamber 43 and a pressure chamber 44, formed, wherein the tension chamber 43 generates a pressure for applying the tensile force in the pulling direction 3. The pressure chamber 44 acts in the opposite direction, so that the expanded by the tensile force expander tool 11 can be retracted for the return stroke.

This in FIG. 4 illustrated embodiment largely corresponds to the in FIG. 1 illustrated embodiment, so that the same or equivalent components are also numbered the same and a repeated explanation of the same to avoid repetition is omitted.

However, at the in FIG. 4 illustrated embodiment differing from the in FIG. 1 illustrated embodiment, the clamping bracket 28 and the drive angle 15 is formed with opposite signs, whereby any release forces that can act on the clamping element 21 during operation, not with the expansion forces but with the forces applied by the abutment forces occur and therefore significantly lower. It is understood that such a configuration is also independently advantageous from the other features of the present embodiment.

Also connect in this embodiment, the clamping elements 29 not only the outer ring 26 and the inner ring 22, but brace the intermediate ring 31 with the outer ring 26 and the inner ring 22 which is disposed between the outer ring 26 and the intermediate ring 31. In this way, regardless of the other features of this embodiment, in a mechanical Zugxpander with an inner ring, an outer ring and another ring, preferably the intermediate ring, the force relationships between the Homogenized inner ring and the outer ring and thus a uniform as possible clamping can be realized.

Also protrudes in this embodiment, the intermediate ring 31 both radially outwardly projecting outer ring 26 and the radially outwardly projecting lubricant ring 32 and the radially outwardly projecting tool drive tool radially, so that the intermediate ring 31 can protect these assemblies from mechanical stresses. Likewise, hydraulic assemblies 34 and the intermediate ring 31 piercing hydraulic lines 33 are protected by this intermediate ring 31 accordingly from mechanical stresses.

Such protection is usually not necessary for the expander tool 11, since this is designed anyway for high mechanical stresses and contact with the pipe. On the other hand, it is readily possible to dimension the Zugxpander 1 such that the Expanderwerkzeuge 11 can be withdrawn so far that they are located radially within the intermediate ring 31 or the tool drive 11 and thus protected by these assemblies when assembly activities such as Transferring a pipe via the Zugxpander 1 or the insertion of the Zugxpanders 1 in a pipe to be performed. By moving the clamping element 21 on the counter-bearing 4 to then the expander tools 11 can be brought to expand radially outward again.

In addition, in this embodiment, the lubricant ring 32 is selected to be radially small, that the hydraulic assemblies 34 are radially within the intermediate ring 31 and radially within the expander tool 11 and the tool drive 12 can be found and protected by these modules.

LIST OF REFERENCE NUMBERS

1

Zugexpander

2

pull bar

3

tensile direction

4

thrust bearing

5

anchor

11

expander tool

12

tool drive

13

inner driving ramp

14

outer driving ramp

15

engine angle

21

clamping element

22

inner ring

23

outer inner ring clamping surface

24

inner inner ring clamping surface

25

Zugstangenklemmfläche

26

outer ring

27

Outer ring clamping surface

28

clamping profile

29

clamping element

31

intermediate ring

32

lubricant ring

33

hydraulic line

34

hydraulic assembly

41

Pulling cylinders

42

traction piston

43

pull chamber

44

pressure chamber

Claims (17)

Mechanical pull expander (1) for pipes (7) with a pull rod (2), with at least one expander tool (11), which exerts a radial expansion force on the pipe (7) by means of a radial movement, with an abutment (4) and with a Tool drive (12), which converts an axial relative movement between the drawbar (2) and the anvil (4) into a radial movement, which drives the Expanderwerkzeug (11) radially, and which with the drawbar (2) by means of a clamping element (21) is axially fixed, wherein the clamping element (21) in a pulling direction (3) of the tie rod (2) acting tensile force by means of a radially to the tie rod (2) applied clamping force on the tool drive (12) transmits, characterized in that the clamping element (21 ) is a mechanically driven clamping element (21), that the tensile force in the pulling direction (3) via the clamping element (21) on an intermediate ring (31) and then on the tool drive (12) is transmitted and / or that the tensile force in Pulling direction (3) via the clamping element (21) on a lubricant ring (32) and then on the tool drive (12) is transmitted. Zugxpander according to claim 1, characterized in that the clamping element (21) has an inner ring (22) with an outer inner ring clamping surface (23) and an axially to the inner ring (22) displaceable outer ring (26) with a to the outer inner ring clamping surface (23) complementary inner Outer ring clamping surface (27). Zugxpander according to claim 2, characterized in that the outer inner ring clamping surface (23) and the inner outer ring clamping surface (27) at least partially correspond to a conical surface. Zugxpander according to claim 2 or 3, characterized in that a clamping angle (28) of the clamping element (21) and a drive angle (15) of the tool drive (12) with respect to a pulling direction (3) of the drawbar (2) have the same sign. Zugxpander according to claim 4, characterized in that the clamping angle (28) relative to the drive angle (15) has a smaller or equal amount. Zugxpander according to one of claims 2 or 3, characterized in that a clamping angle (28) of the clamping element (21) and a drive angle (15) of the tool drive (12) with respect to a pulling direction (3) of the drawbar (2) an opposite Have sign. Zugxpander according to one of claims 2 to 6, characterized in that the outer ring (26) is stiffer than the inner ring (22) is formed. Zugxpander according to one of claims 2 to 6, characterized in that the clamping element (21) comprises at least one annular spring and / or conical surface clamping element. Zugxpander according to any one of the preceding claims, characterized in that an inner inner ring clamping surface (24) of the clamping element (21) and a Zugstangenklemmfläche (25) of the drawbar (2) are cylindrical. Zugxpander according to any one of the preceding claims, characterized in that the clamping element (21) for mechanical clamping at least one axially effective clamping element (29). Zugxpander according to claim 10, characterized in that the clamping element (29) is mechanically formed. Zugxpander according to claim 10 or 11, characterized in that the clamping element (21) has radially circumferentially arranged clamping elements (29). Zugxpander according to any one of the preceding claims, characterized in that the intermediate ring (31) at least one axially before or behind him to the anvil (4) arranged to radially outwardly projecting module protrudes. Zugxpander according to one of claims 2 to 8 and according to claim 13, characterized in that the intermediate ring (31) projects radially beyond the outer ring (26). Zugexpander according to claim 13 or 14, characterized in characterized in that the intermediate ring (31) projects beyond the lubricant ring (32) radially. Zugxpander according to any one of the preceding claims, characterized in that the intermediate ring (31) is pierced by a hydraulic line (33). Zugxpander according to any one of the preceding claims, characterized in that the expander tool (11) and / or the tool drive (12) the lubricant ring (32), in particular including any hydraulic lines (33) and / or any on the lubricant ring (32) arranged hydraulic Subassemblies (34), project radially beyond.

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