EP1474270A1

EP1474270A1 - Method and device for holding a metallic component to be connected, especially a gas turbine blade

Info

Publication number: EP1474270A1
Application number: EP03711820A
Authority: EP
Inventors: Reinhold Meier
Original assignee: MTU Aero Engines GmbH
Current assignee: MEIER, REINHOLD
Priority date: 2002-02-11
Filing date: 2003-02-11
Publication date: 2004-11-10
Also published as: WO2003068457A1; DE10206447A1; US20050205644A1; DE10206447B4; CA2475330A1

Abstract

The invention relates to a method and a device for holding a metallic component to be connected, especially a gas turbine. The inventive method is characterised by the following steps: a metallic component (1) having a surface (2) and at least one working or joint surface (3) is provided; a case (5) comprising a recess which is used to receive the component (1) and has an inner surface (6) is provided; the component (1) is positioned in the case (5) in such a way that its surface (2) is surrounded by the inner surface (6) of the case (5), at a distance, forming a closed volume (8), and the working or joint surface (3) of the component does not face the volume (8); the volume (8) is filled with a foamable material (11); and the material (11) is foamed and cooled, forming a dimensionally stable foam structure. The invention also relates to a method for connecting a metallic component, especially a gas turbine, to another component.

Description

METHOD AND DEVICE FOR HOLDING A METAL COMPONENT TO BE CONNECTED, IN PARTICULAR A GAS TURBINE BLADE

The invention relates to a method and. a device for holding a metallic component to be connected, in particular an airfoil for a gas turbine, and a method for connecting a metallic component, in particular an airfoil for a gas turbine, with a further component.

It is generally desirable that metallic components or their surfaces are not damaged or adversely affected in any way when they are connected to further components. If e.g. B. an airfoil of a stationary gas turbine or an aircraft engine is connected to a blade root, a blade shroud or a carrier of a compressor or turbine rotor by a suitable method, e.g. Welding, the shape and surface of the airfoil must not be adversely affected for aerodynamic or strength reasons. The latter can during the connection process z. B. when holding the airfoil by means of jaws due to the selective application of force and is particularly critical when relatively large forces are introduced.

The problem on which the invention is based is to create a method for holding a metallic component of the type described at the outset, in which the component is treated as gently as possible with regard to its shape and surface during processing. A corresponding holding device is also to be created. In addition, a method for connecting a component held in this way to another component is to be provided.

The solution of the problem according to the invention is described in the method according to claims 1 and 27 and the device according to claim 33.

In the method according to the invention for holding a metallic component to be connected, it is advantageous that the component is held flat and not punctually and its surface is therefore not subjected to punctual loads. The one after cooling The foam structure, which is dimensionally stable at ambient temperature, conforms almost completely to the surface of the component to be connected and provides a play-free, rigid, form-fitting coupling to the component directly or between the cassette, the foam structure and the component. The surface or outer skin of the foam is thus homogeneous and compact that there is no damage to the surface of the component to be connected. Otherwise, the foam structure is cellular and has a porosity. To connect the component to other components by welding or another suitable joining process, large forces can therefore be introduced via the component, e.g. B. for compressing the joining surfaces without the surface of the component being damaged, the shape of the component being changed or additional large-volume projections for applying force to the component having to be removed after the joining process.

Machining or joining surface is to be understood that the method is not only used when the metallic component to be held with its joining surface is joined by another component, e.g. is connected by welding, but also if the metallic component to be held is processed on a processing surface in a further step, such as an almost present in its finished form, e.g. forged or cast, airfoil for a gas turbine, the end face of which is to be finished in a further step, e.g. by milling.

The foamable material usually comprises a foamable base material, e.g. a plastic or a metal, and a blowing agent that forms a gas when heated. In the case of a metal as the base material, the heating is carried out to a foaming temperature which corresponds at least to the melting temperature of the foamable metal and is below the melting temperature of the component material.

Depending on the component material, its surface can be provided beforehand with a preferably metallic protective layer, such as a galvanic Ni layer, in order to optimally protect the component surface against any surface attack during heating or foaming. Finally, cooling always takes place to a temperature below the melting or foaming temperature, preferably to room temperature, with the formation of a dimensionally stable, porous foam structure with a compact outer skin.

The method is for a component of a gas turbine, such as. B. an airfoil, suitable, since these airfoils generally as forged or cast components substantially in their finished form with other components, such as. B. a blade root, a blade shroud or a compressor or turbine carrier, are connected or still need to be processed, e.g. by milling on its face. As a result, the shape or surface of such airfoils must not be selectively damaged during the joining or machining process and should largely be in the finished form.

The cassette can be formed in two or more parts, the individual parts of the cassette being fixed together in a suitable manner after the component has been positioned and the foamable material has been received, for. B. by screws or the like .. The cassette consists of a sufficiently strong and rigid, metallic material, such as Steel.

In the parting line between the parts of the cassette, a detachable spacer element, preferably also made of steel, can be provided to vary the volume in the cassette in order to compensate for any shrinkage of the foam during cooling. The spacer can be removed after cooling. The parts of the cassette are then fixed in abutting manner, reducing the volume around the component, and any shrinkage is compensated for, thereby achieving a rigid coupling between the cassette, the foam structure and the component.

In addition to the base material, such as Al, Mg, Cu, brass, bronze or polystyrene, polyurethane (PS, PUR), the foamable material always contains a blowing agent, such as titanium hydrite, which forms a gas when heated and then forms cells to form it Foam structure from the base material is required. Depending on the strengths and elasticity modules required in the subsequent joining process, a plastic, such as, for. B. polystyrene or polyurethane (PS or PUR), or a metal, such as Al or Mg or Ni or Fe or an alloy of these elements, individually or in combination, can be used to produce the foam structure. The strength and the modulus of elasticity of the foam structure holding the component depends not only on the base material but also on the pore structure and generally increases approximately linearly with the bulk density. The parameters when foaming the base materials mentioned are adapted to the respective application in a manner known to the person skilled in the art. The surface or outer skin of the foam structure is closed, compact and not too rough to protect the surface of the component.

If the base material of the foamable material is a metal, the foaming temperature is at least in the range of its melting temperature and always below the melting temperature of the component material. A metallic foam structure has the advantage of a higher compressive strength compared to a plastic one. When foaming a metal-containing, foamable material, the risk of caking on the component surface is generally lower than with foamable plastics.

The foamable material can, in particular in the case of a metal as the base material of the foamable material, be provided in a dimensionally stable manner as at least one semi-finished product, preferably by sintering the material with a suitable powdery blowing agent. The semi-finished product can be formed with locally different ratios between base material and blowing agent, so that after foaming, a foam structure with locally different porosities or densities is formed.

The more base material is locally present in the semi-finished product compared to the blowing agent, the higher the density after foaming and thus the lower the porosity of the foam structure. Since the compressive strength of the foam structure is approximately proportional to its density, foam structures with variable compressive strengths can be produced. Large forces are applied during further processing. In parts of the component, the foam structure holding the component can have a lower porosity and thus a higher density and greater compressive strength than in other places.

For a foam structure with a high density, the semi-finished product must contain a large proportion of e.g. metallic base material compared to the blowing agent. The density of the foam structure can, as is understandable by the person skilled in the art, also be controlled via the ratio of the volume of the semi-finished product to the closed volume for the foamable material in the cassette. A greater play when filling the closed volume with the semi-finished product leads to greater porosity and thus lower density and lower compressive strength. The semi-finished product can be formed or separated from a large-area sheet metal, adapted to the shape and size of the closed volume. For a closed volume, several semi-finished products with different ratios of base material to blowing agent can be combined, whereby a locally differently porous and consequently dense foam structure can be produced.

The processing or joining surface does not look at the closed volume during positioning and can be accommodated in a correspondingly shaped recess in the cassette and / or can be positioned protruding from the cassette so that it can be used for subsequent processing, e.g. in a welding or milling machine, is not covered by the foam structure and protrudes from the foam structure and possibly from the cassette.

The contact area between the component and the cassette adjacent to the processing or joining surface can be sealed with a soft metal, such as copper or lead, in the form of a ring or strip before foaming in order to compensate for shape or dimensional differences between the component and the cassette in the contact area ,

The component held in the foam structure can be assembled with the cassette or alternatively after removing the cassette in a final step directly with the foam structure in a machine for further processing. The component can be positioned in the cassette using a positioning means, such as a threaded pin, which interacts with the surface of the component in such a way that the component is positioned in the cassette without play. The component can also be provided with an attachment with which the component, preferably with a separate fixing means, such as a screw, is positively positioned in the cassette.

A blade having a stacking axis, a blade tip and two blade edges lying opposite one another can be provided as a component for a gas turbine. The opposite blade edges can contact the cassette when positioning to form two closed volumes, the steps of filling, foaming and cooling in one embodiment being able to be carried out only for one of the two volumes and in the other volume positioning means interacting with the surface of the component, for example Set screws can be provided, on which the component is pressed after foaming.

The paddle can e.g. after casting or forging, with at least one pin projecting coaxially to its stacking axis and from its blade tip and / or its blade root via the blade blade. The pin can be formed with a circular cross section flattened in sections in order to ensure against rotation about the stacking axis when positioning the airfoil in the cassette or following the formation of the foam structure when positioning the airfoil in a processing device or machine.

The pin can be received in a correspondingly shaped recess in the cassette during positioning, so that the pin protrudes from the foam structure formed and can be used for positioning during further processing of the airfoil.

In one embodiment, the method can comprise the further step: assembling the component held in the foam structure with or without a cassette in a machining processing device or a machine. In the case of an airfoil, the method can comprise the further steps: assembling the airfoil held in the foam structure with or without a cassette in a processing device or a machine and positioning the airfoil by means of the projecting pin.

In the method for connecting a metallic component to a further component, the second component also generally consists of metal and, in the case of a gas turbine component, generally consists of a Ti or Ni or Co or Fe alloy. Any welding beads that occur during the joining process or small-volume, optional approaches to one of the components, which simplify the positioning in the cassette, can be reworked or removed locally in a subsequent step, e.g. B. by a machining process.

The holding device for a metallic component to be connected is generally used for further processing in a machine, e.g. B. a welding or milling machine or a robot. The heating device for heating the foamable material can be designed in a suitable manner depending on the application, for example inductively or by gas.

Further refinements of the method and of the device are described in the subclaims.

The invention is explained in more detail below on the basis of exemplary embodiments with reference to a drawing. It shows:

Figure 1 is a sectional, perspective view of a holding device according to the invention with a component held according to the inventive method.

2 shows a sectional, perspective illustration of an exemplary embodiment of a holding device according to the invention, the component being connected to a further component; 3 shows a perspective illustration of two components connected according to an exemplary embodiment of the method according to the invention and of a component to be connected which is held in an exemplary embodiment of a holding device according to the invention; and

4 shows a representation corresponding to FIG. 3 of another exemplary embodiment of the method according to the invention and a further exemplary embodiment of the holding device according to the invention.

1 shows a sectional, perspective illustration of a metallic component 1, which is held in accordance with the method for holding a metallic component in a corresponding holding device, designated overall by 14. In the present embodiment of the method, the metallic component is an airfoil 1 made of a titanium alloy, which, for. B. is used for a compressor of a gas turbine. The airfoil 1 has an outer surface 2 and a joining surface 3 which is connected to a joining surface of a further component, not shown in FIG. 1. In the present embodiment, the airfoil 1 additionally has a shoulder 4 with which the airfoil 1 is fixed in the holding device 14 for precise positioning.

Alternatively, the extension 4 can also be omitted or can be designed like a flattened pin 19 shown in FIG. 4. The pin 19 extends coaxially to the stacking axis 20 of the airfoil 1. The airfoil 1 has the pin 19 as a result of its manufacturing process, e.g. by forging on. The pin 19 is therefore not additionally provided for carrying out the method according to the invention. The pin 19, which extends coaxially to the stacking axis 20, can be used for the exact positioning of the airfoil 1 in the cassette 5 and also for the positioning of the airfoil 1 relative to another component, such as a rotor carrier, to which the airfoil 1 is to be connected.

In the present embodiment, the holding device 14 comprises a two-part cassette 5 made of steel, which has a recess with an inner surface 6. Along a parting line 22 of the two parts of the cassette 5, a spacer element 21 is provided, which after the heating and foaming Cooling is removed. The two parts of the cassette 5 are then joined in an abutting manner to compensate for any shrinkage of the foam during cooling.

The airfoil 1 is positioned in the recess of the cassette 5 in such a way that its joining surface 3 protrudes out of the cassette 5 and its surface 2 is substantially surrounded by the inner surface 6 of the cassette 5, forming a volume 8 which is closed off from the outside. The cassette 5 contacts the airfoil 1 only in a blade region 16 adjoining the joining surface 3 and the shoulder 4 or the pin 19 for more precise positioning.

In the present embodiment of the method, the foamable material 11 is dimensionally stable as a semi-finished product. The shape and size of the two semifinished products forming the foamable material 1 1 are such that they almost completely fill the closed volume 8 between the surface 2 of the airfoil 1 and the inner surface 6 of the cassette 5. In order not to influence the positioning of the airfoil 1 in the cassette 5, the semi-finished products 1 1 are fitted with play.

Positioning pins 9, which touch the surface 2 of the airfoil 1 and are located in the cassette 5, e.g. can be fixed by a thread. Optionally, the airfoil 1 can also be clearly fixed to its attachment 4 by means of a screw 10 on the cassette 5.

After the positioning of the airfoil 1 and the addition of the foamable material 11, which in the present case are two sintered semi-finished products made of Al powder and a suitable blowing agent, the cassette 5 is closed in such a way that the volume 8 represents a closed volume, ie also in the contact area 16, which is suitably kept tight, for example with a strip or ring of a soft metal such as Cu. Subsequently, the foamable material 11 located in the volume 8 is heated to the foaming temperature, which corresponds approximately to the melting temperature of Al. A gas is formed by the blowing agent, which causes the melted AI to foam. After cooling to room temperature, there is a dimensionally stable foam which ensures a positive, rigid connection between the airfoil 1 and the cassette 5.

The cassette 5 has an outer surface on each of its two parts on a projection 13 on which the holding device 14 in a suitable machine, such as. B. a welding machine or a robot can be fixed. As shown by the arrows F, z. B. also a force for connecting the airfoil 1 to another component not shown in FIG. 1 can be introduced.

2 shows a sectional, perspective illustration of an airfoil 1 held in a holding device 14, which is connected to a further component in accordance with an exemplary embodiment of the method according to the invention for connecting two components. 2, the airfoil 1 held in the manner described above is not shown in section and one of the two airfoil edges 15 can be seen.

In the present exemplary embodiment, the airfoil 1 is connected to a rotor carrier 17 by a gas turbine to form a compressor rotor. The rotor carrier 17 consists of a titanium alloy and has on its circumferential surface a multiplicity of equidistantly spaced joining surfaces 18 which are each connected to an airfoil 1 according to the method according to the invention.

In the present embodiment of the method, the connection of the airfoil 1 held in the holding device 14, as described above, to the carrier 17 takes place by induction welding. For this purpose, the joining surfaces 3 and 18 of the airfoil 1 and the rotor carrier 17 are positioned essentially flush and slightly spaced apart from one another, heated by means of an inductor (not shown) which surrounds the joining plane E circumferentially, and then moved together. This results in only a small weld bead 19, which is finally removed by local reworking. Likewise, the merely optional attachment 4 of the airfoil 1 is removed after the connection process and the airfoil tip 20 of the airfoil 1 is locally processed.

This connection process is done with the required number of airfoils

1 is repeated on the other joining surfaces 18 of the rotor carrier 17, so that finally an integrally vane rotor with a plurality of substantially radially extending blades 1 is created. The rotor can be used in a compressor of a gas turbine. Alternatively, a turbine rotor of a gas turbine can be manufactured in a corresponding manner, wherein the components to be connected can always consist of different materials.

The blade blade 1 shown in FIG. 2, which has a blade tip 12 and two opposite blade edges 15, can alternatively be positioned in the cassette 5 such that the opposite blade edges 15 contact the cartridge 5 to form two closed volumes 8 ', 8 " In the embodiment, the steps of filling, foaming and cooling can only be carried out for one of the two volumes 8 ′ and in the other volume 8 ″, positioning means 9 interacting with the surface 2 of the component 1 and, unlike in FIG.

2 shown, no foamable material 1 1 are provided.

3 shows a perspective view of an airfoil 1 connected to a rotor carrier 17, in which the welding bead 19 as well as the attachment 4 have already been removed. A further airfoil 1 ′, which is held in a holding device 14 and is subsequently connected to the carrier 17, is positioned on a further joining surface 18 ′ of the carrier 17. A spacer element 21 is provided between the two parts of the cassette 5. The spacer 21 can be removed after cooling to form the foam to compensate for any shrinkage of the foam. By moving the two parts of the cassette 5 together when these parts are subsequently connected, the volume 8 is reduced in accordance with the shrinkage. The spacer element 21 can also remain in the joint 22 of the two parts of the cassette 5 during the joining process. In general, all shovel blades first! , 1 'connected to the carrier 17 and subsequently carried out any reworking on welding beads 19 or the like.

In an alternative method, the airfoil 1 can be connected to the carrier 17 by means of linear friction welding. Due to the rigid connection between the cassette 5 and the airfoil 1 to be connected as a result of the dimensionally stable foam structure, relatively large forces when the joining surfaces 3, 18 are pressed together during oscillation can be transmitted via the airfoil 1 which is almost in its finished form. For easier positioning in the cassette 5, the airfoil 1 can also have an extension 4 or a pin 19 which extends coaxially to the stacking axis 20 of the airfoil 1 in this method.

FIG. 4 shows such a pin 19, which has a flattened circular cross section and thus ensures security against rotation about the stack axis 20. The pin 19 extends from the blade tip 12 away from the airfoil 1. This pin 19, which lies in the stacking axis 20 of the airfoil 1 and protrudes from the foam structure, facilitates the positioning of the airfoil 1 during a subsequent connection process, e.g. by welding, with a further component, such as a rotor carrier 17, which is defined, inter alia, by its axial axis, its diameter or its length.

In the cassette 5 shown in FIG. 4, no spacer element 21 is provided along the parting line 22. The pin 19 is positioned in a recess in the cassette 5 and thus protrudes from the foam structure formed in the volume 8. For heating and foaming, the parting line 22 between the parts of the cassette 5 and thus also in the region of the projecting pin 19 must be tight. Depending on the wall thickness of the cassette 5 and the length of the pin 19, this protrudes from the cassette 5.

Claims

claims

1. A method for holding a metallic component to be connected, in particular a gas turbine, characterized by the steps:

Providing a metallic component (1) with a surface (2) and at least one processing or joining surface (3),

Providing a cassette (5) with a recess for receiving the component (1), which has an inner surface (6),

Positioning the component (1) in the cassette (5) in such a way that its surface (2) is surrounded by the inner surface (6) of the cassette (5) to form a closed volume (8) and its processing or joining surface (3) does not look at the volume (8), filling the volume (8) with a foamable material (1 1), foaming the material (1 1) and cooling to form a dimensionally stable foam structure.

2. The method according to claim 1, characterized by the provision of a component (1) made of a Ti or Ni or Co or Fe alloy.

3. The method according to claim 1 or 2, characterized by the provision of a two-part or multi-part cassette (5), the parts of which are fixed together after being positioned by screwing or bracing.

4. The method according to claim 3, characterized by the provision of at least one spacer element (21) in a parting line (22) of the parts of the cassette (5) for changing the volume (8).

5. The method according to any one of the preceding claims, characterized in that the surface (2) of the component (1) to the inner surface (6) of the cassette (5) is positioned equidistantly objected.

6. The method according to any one of the preceding claims, characterized in that the processing or joining surface (3) is accommodated in the cassette (5) during positioning in a correspondingly shaped recess.

7. The method according to claim 6, characterized in that the processing or joining surface (3) from the cassette (5) is positioned above.

8. The method according to claim 7, characterized in that a contact area (16) adjacent to the machining or joining surface (3) between the component (1) and the cassette (5) is sealed with a soft metal, such as copper or lead, before foaming ,

9. The method according to any one of the preceding claims, characterized by positioning the component (1) in the cassette (5) with a with the surface (2) of the component (1) interacting positioning means (9).

10. The method according to any one of the preceding claims, characterized by providing the component (1) with an approach (4) with which the component (1), preferably with a separate fixing means (10), is positioned in the cassette (5) ,

1 1. The method according to any one of the preceding claims, characterized in that the foamable material (1 1) is provided with a plastic as the base material, such as polyurethane (PUR), or a metal as the base material and a suitable blowing agent.

12. The method according to claim 1 1, characterized in that the metal AI or Mg or Ni or Fe or Cu or brass or bronze or an alloy of these elements is provided individually or in combination.

13. The method according to any one of the preceding claims, characterized in that the foamable material (1 1) is provided as a powder.

14. The method according to any one of the preceding claims 1 to 12, characterized in that the foamable material (1 1) is provided dimensionally stable as at least one semi-finished product, preferably by sintering the material.

15. The method according to claim 14, characterized in that the semi-finished product is formed with locally different ratios between the base material and the blowing agent.

16. The method according to any one of the preceding claims, characterized by the further step before positioning:

Coating the component (1) with a preferably metallic protective layer, such as a galvanic Ni layer.

17. The method according to any one of the preceding claims, characterized in that the foamable material (1 1) is foamed in the case of a metal as the base material by heating to a foam temperature corresponding at least to its melting temperature and in the case of a plastic as the base material using a chemical or physical blowing process.

18. The method according to claim 17, characterized by heating by induction or by gas or in an oven.

19. The method according to any one of the preceding claims, characterized in that a blade (1) having a stacking axis (20), a blade tip (12) and two opposite blade edges (15) is provided as a component (1) for a gas turbine.

20. The method according to claim 19, characterized in that the opposite blade edges (15) contact the cassette (5) during positioning to form two closed volumes (8 ', 8 ").

21. The method according to claim 20, characterized in that the steps of filling, foaming and cooling are carried out only for one of the two volumes (8 ') and in the other volume (8 ") with the surface (2) of the component (1) interacting positioning means (9) are provided.

22. The method according to any one of claims 19 to 21, characterized in that the blade bellow (1) with at least one projecting coaxially to the stack axis (20) and from the blade tip (12) and / or the blade root of the blade (1) Pin (19) is provided.

23. The method according to claim 22, characterized in that the pin (19) is formed with a circular cross-section flattened in sections.

24. The method according to claim 22 or 23, characterized in that the pin (19) is received during positioning in a correspondingly shaped recess (23) in the cassette (5).

25. The method according to any one of the preceding claims, characterized by the further step:

Assembly of the component (1) held in the foam structure with or without a cassette (5) in a processing device or a machine.

26. The method according to any one of claims 22 to 24, characterized by the further steps:

Assembling the airfoil (1) held in the foam structure with or without a cassette (5) in a processing device or a machine and positioning the airfoil (1) by means of the projecting pin (19).

27. Method for connecting a metallic component to another component, characterized by the steps:

Holding a metallic component (1) with a joining surface (3) according to a method according to one of claims 1 to 26,

Providing a second component (17) with at least one joining surface (18), positioning the joining surface (3) of the component (1) to the joining surface (18) of the second component (17), Connect the components (1, 17) by heating and contacting the joining surfaces (3, 18).

28. The method according to claim 27, characterized in that the connection is carried out by welding.

29. The method according to claim 27 or 28, characterized in that the components (1, 17) are connected by friction welding in such a way that the welding temperature by pressing together the joining surfaces (3, 18) and simultaneously oscillating relative movement of the components (1, 17th ) in the joining plane (E).

30. The method according to claim 27 or 28, characterized in that the components (1, 17) are connected by means of induction welding by heating the joining surfaces (3, 18) with an inductor and then contacting the joining surfaces (3, 18).

31. The method according to any one of claims 27 to 30, characterized in that as a component to be connected (1) a blade and as a second component a blade root or a blade shroud or a rotor carrier (17) of a gas turbine with a plurality of circumferentially arranged joining surfaces (18) provided.

32. The method according to claim 31, characterized in that the method is repeated in accordance with the number of joining surfaces (18) of the rotor carrier (17) with a corresponding number of blades (1).

33. Holding device for a metallic component to be connected, in particular a gas turbine, comprising: a cassette (5) with a recess having an inner surface (6) for receiving a metallic component (1) with a surface (2) and a machining processing or joining surface (3) and a foamable material (1 1) containing metal as the base material to form a dimensionally stable foam structure surrounding the surface (2) of the component (1) with the exception of its processing or joining surface (3), and a heating device for heating the material (1 1) to a foaming temperature corresponding at least to its melting temperature.

34. Holding device according to claim 33, characterized by a two-part or multi-part cassette (5), the parts of which can be fixed together by screwing or bracing.

35. Holding device according to claim 34, characterized by at least one releasable distance element (21) in a joint (22) of the cassette (5).

36. Holding device according to one of claims 33 to 35, characterized by a cassette (5) with at least one shoulder (13) on its outer surface (7) for fixing in a processing device or a machine and / or for applying force to a joining plane (E ) during a welding process.

37. Holding device according to one of claims 33 to 36, characterized by a foam structure (1 1) with locally different density.