Welding tool comprising a rotating probe, welding method and workpiece

Abstract

A welding tool for joining at least two workpieces at a joining region by friction stir welding includes a tool pin arranged along one axis of the welding tool, for applying frictional heat to the workpieces. The welding tool also includes a shoulder surrounding the tool pin, for separating the joining region from the surrounding area. The shoulder is moveable essentially parallel to the axis of the welding tool.

Claims

1. A welding tool for joining at least two workpieces at a joining region by friction stir welding, the welding tool comprising: a tool pin arranged along one axis of the welding tool, wherein the tool pin is configured to apply frictional heat to the workpieces at the joining region during the friction stir welding; and shoulder surrounding the tool pin, wherein the shoulder is arranged to separate the joining region from a surrounding area, wherein the shoulder is configured to be moveable parallel to the one axis, wherein the tool pin has, in a direction of the one axis, a projection that projects beyond the shoulder end region, wherein the projection is controlled by a displacement of the shoulder parallel to the one axis.

2. The welding tool of claim 1, wherein the shoulder has an elastic area.

3. The welding tool of claim 2, wherein the elastic area is formed by a spring arrangement.

4. The welding tool of claim 2, wherein the elastic area is formed on a shoulder end region that faces at least one of the workpieces during normal operation.

5. The welding tool of claim 1, wherein a maximum possible motion path of the shoulder corresponds to the projection.

6. The welding tool of claim 1, wherein the tool pin is removably mounted on a tool pin holder.

7. The welding tool of claim 6, wherein the tool pin holder is rotatably mounted about the one axis.

8. The welding tool of claim 6, wherein the shoulder is integrally formed with the tool pin holder.

9. The welding tool of claim 6, wherein the shoulder is mounted separately from the tool pin holder in such a way that the shoulder is rotatable about the one axis or in such a way that the shoulder is stationary.

10. The welding tool of claim 6, wherein the tool pin holder has a cone shape in a longitudinal section along the one axis.

11. The welding tool as claimed in claim 1, wherein the shoulder has a cone shape in a longitudinal section along the one axis or has an L shape.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

(1) Preferred embodiments of the invention will be explained in detail below with reference to the accompanying drawings. The drawings show in:

(2) FIG. 1 a longitudinal sectional view of a first embodiment of an inventive welding tool for friction stir welding with a tool pin and a shoulder.

(3) FIG. 2 the welding tool from FIG. 1 when welding a workpiece to a thick workpiece.

(4) FIG. 3 the welding tool from FIG. 1 when welding a workpiece to a thin workpiece; and

(5) FIG. 4 a second embodiment of an inventive welding tool from FIG. 1.

DETAILED DESCRIPTION

(6) FIG. 1 is a longitudinal sectional view of a first embodiment of a welding tool 10 comprising a tool pin 12 and a shoulder 14.

(7) The tool pin 12 is attached to a tool pin holder 16, which is mounted in a manner allowing rotation about an axis A in the direction of the arrow.

(8) In the illustrated embodiment the tool pin holder 16 is designed in the shape of a cylinder; and the tool pin 12 tapers off towards a tool pin end region 18, which projects through a shoulder opening 20 into a surrounding area 22. As a result, the tool pin 12 projects beyond a shoulder end region 24 by a projection I.

(9) The shoulder 14 is arranged separately from the tool pin holder 16 and is movable along the axis A in the direction of the arrow that is shown.

(10) The shoulder 14 is configured in essence as a cylinder shape around the axis A and has an L shape in the longitudinal section. In this case, bars 26, which are directed toward the tool pin 12 and which exhibit an L shape in the longitudinal section, are adapted to the tapering of the tool pin 12.

(11) FIGS. 2 and 3 show a welding process for joining two workpieces 28, 30 in a joining region 32 by means of friction stir welding using the welding tool 10.

(12) In FIG. 2 the first workpiece 28 has a greater thickness than the first workpiece 28 in FIG. 3. The first workpiece 28 in FIG. 2 has, for example, a thickness of 4 mm, whereas the first workpiece 28 in FIG. 3 has, for example, a thickness of 2 mm. Working on this basis, in order to join the workpieces 28, 30 in order to achieve a T shaped end workpiece 33, the tool pin 12 penetrates deeper into the first workpiece 28 in FIG. 2 than in FIG. 3. This is achieved in that the shoulder 14 is movable along the axis A; and, as a result, the tool pin 12 can protrude further from the shoulder 14. Therefore, it is also possible to weld together the workpieces 28, 30, which have welding depths 34 that vary over the joining region 32.

(13) FIG. 4 shows a second embodiment of a welding tool 10.

(14) In this case the tool pin holder 16 as well as the shoulder 14 are formed in the shape of a cone and taper off towards the shoulder end region 24. With the simultaneous L shaped design of the shoulder 14 in the shoulder end region 24, it is now possible to bring the shoulder 14 especially close to the tool pin 12 and, thus, enable a particularly good isolation of the resulting weld seam from the surrounding area 22.

(15) In the embodiment that is shown, the shoulder 14 and the tool pin holder 16 are mounted separately from each other. In this case the tool pin holder 16 can be rotated about the axis A. This feature is achieved by means of a spindle 36, on which the tool pin holder 16 is secured.

(16) The shoulder 14 has an elastic area 37 on the shoulder end region 24, due to the fact that the shoulder end region 24 is divided into two shoulder end subregions 37a, 37b, and a spring arrangement 38 is provided in the space between the shoulder end subregions 37a, 37b. If at this point a force F, which is directed more or less 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 subregion 37a and the second shoulder end subregion 37b is changed. At the same time the projection I of the tool pin 12 beyond the shoulder 14 also changes. In essence the projection I corresponds to the maximum possible motion path of the second shoulder end subregion 37b, where said maximum possible motion path is defined by the spring arrangement 38.

(17) With the welding tool 10 different joint thicknesses can be joined together by means of friction stir welding.

(18) To date, when welding with a varying joint thickness, the tool pin 12 had to be either changed, and as a result, the welding process had to be interrupted before it could be continued with the modified or rather adapted tool pin 12. As an alternative, a so called retractable tool pin 12 was used that could be moved vertically inside the tool pin holder 16, in order to achieve a change in the length of the tool pin 12.

(19) With the welding tool 10 a change in the length of the tool pin 12 can be achieved not by moving the tool pin 12 inside the tool pin holder 16, but rather the shoulder 14 is designed in such a way that said shoulder can be moved, in particular, at the shoulder end region 24; and/or said shoulder is designed elastically, in particular, at the shoulder end region. The result is a deformation or deflection through the introduction of force. The free length of the tool pin 12 and, thus, the welding depth 34 in the joining region 32 correlate with the degree of deflection or more specifically the amount of deformation.

(20) Therefore, it is not necessary to change the welding tool in the course of welding at one and the same component or workpiece 28, 30. Moreover, a significantly simpler welding tool design is achieved, in order to provide, with such a design, different lengths of the tool pin 12 in the welding tool 10.

(21) In this respect the shoulder 14 can be designed in such a manner that it is rigid and does not rotate or in such a manner that it rotates with the tool pin 12. The tool pin 12 is mounted preferably on a spindle 36, which is rotatably mounted. In this case the tool pin 12 cannot be displaced along the axis A, but rather the shoulder 14 is displaceable. The projection I of the tool pin 12 beyond the shoulder 14 is controlled by the displacement of the shoulder 14 along the axis A.

(22) It is advantageous that the displacement of the shoulder 14 along the axis A is much easier and simpler to implement than a displacement of the tool pin 12, so that the result is a tool pin projection that is simpler, more robust and cheaper. No additional closed loop control is required; the projection I is controlled only by introducing a force.

(23) In addition, it has proven to be advantageous that a cleaning effect is obtained at the end of the welding process through a repeated displacement of the shoulder 14 along the axis A.

(24) As a result, sticking of the welding tool 10, the tool pin 12 or the tool pin holder 16 can be avoided. In this respect, an embodiment of the tool pin holder 16 and the bar 26 with a conical longitudinal section is particularly advantageous.

(25) Different root and flange thicknesses can be connected to each other by means of the variable welding depth 34 of the tool pin 12.

(26) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.

LIST OF REFERENCE NUMERALS

(27) 10 welding tool 12 tool pin 14 shoulder 16 tool pin holder 18 tool pin end region 20 shoulder opening 22 surrounding area 24 shoulder end region 26 bar 28 first workpiece 30 second workpiece 32 joining region 33 end workpiece 34 welding depth 36 spindle 37 elastic area 37a first shoulder end subregion 37b second shoulder end subregion 38 spring arrangement A axis I projection F force