EP2720823A2

EP2720823A2 - Welding tool comprising a rotating probe, welding method and workpiece

Info

Publication number: EP2720823A2
Application number: EP12740292.3A
Authority: EP
Inventors: Jürgen Silvanus; Erich Forster; Eric TAUSCHER
Original assignee: EADS Deutschland GmbH
Current assignee: Airbus Defence and Space GmbH
Priority date: 2011-06-15
Filing date: 2012-06-01
Publication date: 2014-04-23
Also published as: DE102011106506A1; US20140326392A1; WO2012171523A3; US9796133B2; WO2012171523A2

Abstract

The invention relates to a welding tool (10) for connecting at least two workpieces (28, 30) in a connection region (32) by means of friction stir welding. The welding tool (10) comprises a probe (12) arranged along an axis (A) of the welding tool (10), for applying friction heat to the workpieces (28, 30), and a shoulder surrounding the probe (12), for separating the connection region (32) from the surroundings (22). The shoulder (14) is mobile essentially parallel to the axis (A). The invention also relates to a welding method and to a workpiece (33) that has been produced using the welding tool (10) or the welding method.

Description

WELDING TOOL WITH ROTATING PROBE, WELDING METHOD AND WORKPIECE

The invention relates to a welding tool for connecting at least two workpieces to a connecting region by means of friction stir welding.

In friction stir welding, in contrast to friction welding, the friction energy is not generated by rotating one of the two workpieces to be joined relative to the other workpiece, but instead uses a wear-resistant welding tool that applies rotational energy to both workpieces at the same time. The following steps are performed:

In the first step, the welding tool is pressed with a rotating probe with high force between the two workpieces to be joined until a probe enclosing shoulder of the welding tool comes to rest on the surface of the workpieces.

In the second step, the rotating probe remains at the point of immersion for a short time, with the area between the shoulder of the welding tool and the workpieces heating to just below the melting point of the workpieces. In this case, the material of the workpieces is softened and plasticized, so that a mixing between the materials of the workpieces to be joined in the connection region is possible.

In the third step, the welding tool is moved in the feed direction, such that the shoulder continues to be pressed with great force onto the workpiece surface and the probe thus into the connection region. It arises during the feed movement, a pressure difference between the front of the

Welding tool and its back by the rotation of the probe, so that plasticized material is transported around the probe, mixed and thus contributes to the formation of welds.

CONFIRMATION COPY At the end of the weld, the welding tool is pulled out of the connection area.

The welding tool accordingly has the probe and a shoulder disposed substantially perpendicular thereto with a larger diameter than the probe itself. The shoulder serves to isolate the ambient air from the weld, while the probe is responsible for the swirling of the material. Since the material by the swirling for weld formation. is used, additional materials are not necessary. Next can also be dispensed with a protective gas atmosphere.

The disadvantage, however, is that the exit of the probe creates a terminal crater at the end of the weld. Furthermore, it has hitherto also been problematic to weld changing welding depths between two workpieces to be joined, since a new probe with a different length always had to be mounted on the welding tool for this purpose.

So far, to solve the above-mentioned problems, it has been proposed to use an automatically retractable probe that can be moved vertically within a probe holder of the welding tool. Of the

However, welding tool construction becomes complicated and susceptible to wear.

The object of the invention is therefore to achieve a change in length of the probe with a simple tool structure, which is less susceptible to wear.

This object is achieved with a welding tool with the feature combination of claim 1. A welding method and a workpiece, which is produced with the welding tool and / or the welding method are the subject of the additional claims.

Preferred embodiments of the invention are the subject of the dependent claims.

A welding tool for joining at least two workpieces by means of friction stir welding at a connection portion has a probe arranged along an axis of the welding tool for applying frictional heat to the workpieces and a shoulder enclosing the probe for separating the connection portion from the environment. The shoulder is designed to be movable substantially parallel to the axis.

By making the shoulder movable, it is possible to bring the probe enclosed by the shoulder with different path lengths from the shoulder. It is thus possible to achieve different penetration depths using one and the same probe. Further, with this welding tool, workpieces with varying or different impact thicknesses can be easily connected without interrupting the welding process.

Preferably, the shoulder has an elastic region. Then it can be advantageous simply by force parallel to the axis effecting a pushing back of the shoulder, so that the probe further protrudes from the shoulder. When the force is released, the shoulder expands again, so that the probe again enters the shoulder and thus advantageously allows shorter penetration depths.

Particularly preferably, the elastic region is formed by a spring arrangement. This is particularly easy to achieve by using heat-resistant materials. elasticity of the shoulder can be achieved. Alternatively, elastic materials can also be provided as cushions at a suitable point on the shoulder in order to be able to displace them parallel to the axis by the action of force.

Preferably, the elastic region is formed on a shoulder end region, which is to be used in operation at least one of the workpieces. Thus, a stable overall shoulder structure can be achieved, wherein only the lower region, namely the shoulder end region, has the elastic region and thus makes the shoulder movable parallel to the axis.

Advantageously, the probe has a projection in the direction of the axis for overhanging the shoulder end region. This supernatant can also be referred to as the probe end region or probe tip.

Particularly preferably, a maximum possible path of movement of the shoulder substantially corresponds to the projection of the probe over the shoulder end region. Thus, it is advantageously possible to completely retract the probe into the shoulder and thus to clean it by the movement. For example, the maximum possible movement path between 0 to 10 mm, in particular between 2 to 4 mm, lie.

Further advantageously, the probe is removably attached to a probe holder so that it preferably can be easily removed from the probe holder and replaced with a new probe.

In a preferred embodiment, the probe holder is rotatably mounted about the axis, so that rotates automatically upon rotation of the probe holder, the probe itself. A rotatable mounting of the probe itself can thus be omitted preferably. Advantageously, the shoulder is integrally formed with the probe holder. In such an arrangement, the shoulder can rotate simultaneously with the probe about the same axis at the same angular velocity.

Alternatively, the shoulder may be rotatably supported or fixedly disposed about the axis apart from the probe support. Thus, for example, a different angular velocity between the probe and the shoulder can be achieved, or the shoulder can firmly enclose the probe without rotation.

Preferably, the probe holder is formed conically in longitudinal section along the axis. Then, the shoulder already extending along the probe support in the direction of the axis can be brought closer to the probe at the shoulder end region, whereby preferably a better sealing against the ambient air can be achieved.

Therefore, it is advantageous if the shoulder in longitudinal section along the axis is conical and / or substantially L-shaped.

A welding method for joining at least two workpieces with welding depths varying along a connecting region by friction stir welding using a welding tool described above comprises the following steps:

a) contacting the shoulder with at least one workpiece;

b) applying a substantially parallel to the axis aligned force on the shoulder until the probe has completely penetrated into a connecting region of the at least two workpieces;

c) changing the force for changing the depth of penetration of the probe in the connection area with continuous contact of the shoulder with the connection area. With this method also workpieces with varying or different impact thickness can be easily connected without interrupting the welding process.

Preferably, after welding, removal of the shoulder from the at least one workpiece and adjustment of the shoulder parallel to the axis, so that the probe can be cleaned so easily.

A workpiece is preferably made with the welding tool described above and / or with the welding method described above.

Preferred embodiments of the invention will be explained in more detail with reference to the accompanying drawings. It shows:

1 shows a longitudinal section through a first embodiment of a welding tool according to the invention for friction stir welding with probe and shoulder.

FIG. 2 shows the welding tool from FIG. 1 during welding of a workpiece with a thick workpiece; FIG.

FIG. 3 shows the welding tool from FIG. 1 during welding of a workpiece with a thin workpiece; FIG. and

4 shows a second embodiment of a welding tool according to the invention from FIG. 1.

Fig. 1 shows a longitudinal section through a first embodiment of a

Welding tool 10 with a probe 12 and a shoulder 14th

The probe 12 is attached to a probe holder 16 which is rotatably mounted about an axis A in the arrow direction. In the embodiment shown, the probe holder 16 is cylindrically shaped and the probe 12 tapers towards a probe end region 18 which projects through a shoulder opening 20 into an environment 22. The probe 12 is thus protruding beyond a projection I via a shoulder end region 24.

The shoulder 14 is arranged separately from the probe holder 16 and is movable in the direction of the arrow along the axis A.

The shoulder 14 is substantially cylindrical in shape about the axis A and has an L-shape in a longitudinal section, with beams 26 of the L-shape aligned in the longitudinal direction of the probe 12 being aligned with the probe 12.

FIGS. 2 and 3 show a welding process for connecting two workpieces 28, 30 to a connecting region 32 by means of friction stir welding using the welding tool 10.

2, the first workpiece 28 has a greater thickness than the first workpiece 28 in Fig. 3. The first workpiece 28 in Fig. 2, for example, has a thickness of 4 mm, while the first workpiece 28 in Fig. 3, for example has a thickness of 2 mm. Accordingly, to connect the workpieces 28, 30 to reach a T-shaped end workpiece 33, the probe 12 in FIG. 2 must dive deeper into the first workpiece 28 than in FIG. 3. This is achieved by shoulder 14 along the axis A is movable and thus the probe 12 can continue to emerge from the shoulder 14. It is thus also possible to weld workpieces 28, 30 together, which have welding depths 34 that change over the connecting region 32.

4 shows a second embodiment of a welding tool 10. Here, the probe holder 16 and the shoulder 14 are tapered and taper towards the Schulterendbereich 24. With simultaneous L-shaped design of the shoulder 14 in the shoulder end region 24, it is now possible to bring the shoulder 14 particularly close to the probe 12 and thus to effect a particularly good insulation of the resulting weld from the environment 22.

In the embodiment shown, the shoulder 14 and the probe holder 16 are mounted separately from each other, wherein the probe holder 16 is rotatable about the axis A. This is achieved by a spindle 36 to which the probe holder 16 is attached.

At the shoulder end region 24, the shoulder 14 has an elastic region 37 in that the shoulder end region 24 is divided into two shoulder end regions 37a, 37b and a spring arrangement 38 is provided in the intermediate space between the shoulder end regions 37a, 37b. If a force F aligned substantially parallel to the axis A is applied to this spring arrangement 38, the spring arrangement 38 is compressed and the space between the first shoulder end portion 37a and the second shoulder end portion 37b is changed. In this case, the supernatant I of the probe 12 also changes over the shoulder 14. Essentially, the supernatant I corresponds to the maximum possible movement path of the second shoulder end portion 37b predetermined by the spring arrangement 38.

By means of the welding tool 10, different impact thicknesses can be combined via friction stir welding.

Previously, when welding with varying impact thickness, the probe 12 had either to be changed, with the welding process had to be interrupted before it could be continued with the modified or adapted probe 12. Alternatively, a so-called retractable probe 12 was used. which could be moved vertically within the probe holder 16 in order to achieve a change in length of the probe 12.

With the welding tool 10, a change in length of the probe 12 can now be achieved in that the probe 12 is not moved within the probe holder 16, but that the shoulder 14 is designed to be movable and / or elastic, in particular at the shoulder end region 24. As a result, a deformation or deflection is effected via an introduction of force. With the extent of this deflection or deformation, the free probe length 12 and thus the welding depth 34 correlate with the connection region 32.

Therefore, no welding tool replacement is required during welding on one and the same component or workpiece 28, 30, and a significantly simpler welding tool configuration is achieved in order to provide different probe lengths 12 in the welding tool 10.

The shoulder 14 may be rigid and non-rotating or may be formed with the probe 12 for co-rotation. The probe 12 is preferably arranged on a spindle 36 which is rotatably mounted. The probe 12 is not adjustable along the axis A, but the shoulder 14. The projection I of the probe 12 via the shoulder 14 is controlled by the adjustment of the shoulder 14 along the axis A.

Advantageously, the adjustment of the shoulder 14 along the axis A is technically much easier to implement than an adjustment of the probe 12 and thus a simpler, more robust and cheaper probe projection is achieved. No additional control is required, the supernatant I is regulated only by the introduction of a force.

Further advantageously results at the end of Schweißverfährens a cleaning effect by repeated adjustment of the shoulder 14 along the axis A, whereby a Seizure of the welding tool 10, the probe 12 or the probe holder 16 can be avoided. Particularly advantageous is an embodiment of the probe holder 16 and the beam 26 with a conical longitudinal section.

About the variable weld depth 34 of the probe 12 different web and flange thicknesses can be interconnected.

List of Reference Numerals: 0 welding tool

2 probe

4 shoulder

16 probe holder

18 probe end area

0 shoulder opening

2 environment

4 shoulder end area

26 bars

28 first workpiece

30 second workpiece

32 connection area

33 end workpiece

34 welding depth

36 spindle

37 elastic range

37aerster Schulterendteilbereich

37bzweiter shoulder end portion

38 spring arrangement

A axis

I supernatant

F force

Claims

claims

1 . Welding tool (10) for connecting at least two workpieces (28, 30) to a connecting region (32) by means of friction stir welding, with a probe (12) arranged along an axis (A) of the welding tool (10) for applying frictional heat to the workpieces ( 28, 30) and with a probe (12) enclosing shoulder (14) for separating the connecting portion (32) from the environment (22),

characterized in that the shoulder (14) is designed to be movable substantially parallel to the axis (A).

2. welding tool (10) according to claim 1,

characterized in that the shoulder (14) has an elastic region (37).

3. welding tool (10) according to claim 2,

characterized in that the elastic region (37) is formed by a spring arrangement (38).

4. welding tool (10) according to any one of claims 2 or 3,

characterized in that the elastic region (37) is formed on a shoulder end region (24), which is to be turned during operation at least one of the workpieces (28, 30).

5. welding tool (10) according to claim 4,

characterized in that the probe (12) in the direction of the axis (A) has a projection (I) for protruding over the Schulterendbereich (24).

6. welding tool (10) according to claim 5, characterized in that a maximum possible path of movement of the shoulder (14) substantially corresponds to the projection (I).

7. welding tool (10) according to any one of the preceding claims, characterized in that the probe (12) is removably disposed on a probe holder (16).

8. welding tool (10) according to claim 7,

characterized in that the probe holder (16) is rotatably mounted about the axis (A).

9. welding tool (10) according to any one of claims 7 or 8,

characterized in that the shoulder (14) is integral with the probe support (16).

10. welding tool (10) according to any one of claims 7 to 9,

characterized in that the shoulder (14) separated from the probe holder (16) about the axis (A) is rotatably mounted or fixedly arranged.

1 1. welding tool (10) according to any one of claims 7 to 10,

characterized in that the probe holder (16) is formed conically in longitudinal section along the axis (A).

12. Welding tool (10) according to any one of the preceding claims, characterized in that the shoulder (14) in longitudinal section along the axis (A) is conical and / or substantially L-shaped.

Welding method for joining at least two workpieces (28, 30) with varying welding depth (34) along a connecting region (32) by friction stir welding using a welding tool (10) according to one of the preceding claims, comprising the steps: a) contacting the shoulder (14) with at least one workpiece (28, 30); b) applying a substantially parallel to the axis (A) aligned force (F) on the shoulder (14) until the probe (12) has completely penetrated into a connecting region (32) of the at least two workpieces (28, 30);

c) changing the force (F) to change the welding depth (34) of the probe (12) in the connecting region (32) upon continuous contact of the shoulder (14) with the connecting region (32).

14. Welding method according to claim 13,

characterized by removing the shoulder (14) from the at least one workpiece (28, 30) and displacing the shoulder (14) parallel to the axis (A) to clean the probe (12).

15. workpiece (33) produced with a welding tool (10) according to any one of claims 1 to 12 and / or with a welding method according to any one of claims 13 or 14.