Tool for Friction Stir Welding and Method for Producing Panels

Abstract

The invention makes available a tool for friction stir welding, which makes it possible, with reduced effort, to connect two panel elements that butt up against one another with one another by means of friction stir welding, in the case of which a tunnel is formed in the region of the abutting side surfaces, by means of recesses formed in the manner of a channel in the side surfaces in question. For this purpose, the tool has a central axle configured in the manner of a pin, provided for coupling to a drive device, a first friction shoulder carried by the central axle, a second friction shoulder carried by the central axle at a distance from the first friction shoulder in the longitudinal direction of the central axle, two support shoulders carried by the central axle, arranged between the friction shoulders, one of which is mounted on the central axle in an axially displaceable manner, and an elastic element that is arranged between the support shoulders, and exerts an elastic force the axially displaceable support shoulder, which force is directed to the friction shoulder most closely adjacent, in each instance, to the axially displaceable support shoulder in the direction. According to the invention, the setting device includes a setting element that is driven outward, away from the central axle of the tool, in the radial direction, during use, by means of the centrifugal forces that are then in effect, and, during this process, acts against a slanted surface formed on the support shoulder, in each instance.

Claims

1. A tool for friction stir welding, having a central axle that is configured in the manner of a pin and provided for being coupled to a drive device, having a first friction shoulder that is carried by the central axle, having a second friction shoulder that is carried by the central axle at a distance from the first friction shoulder, in the longitudinal direction of the central axle, having two support shoulders carried by the central axle, which shoulders are arranged between the friction shoulders, and at least one of which is mounted so as to be axially displaceable on the central axle, and having a setting device that is arranged between the support shoulders and set up for exerting a force during use, at least on the axially displaceable support shoulder, which force is directed in the direction of the friction shoulder arranged most closely adjacent to the axially displaceable support shoulder, in each instance, wherein the setting device comprises a setting element that is driven, during use, by means of the centrifugal forces that are then in effect, in the radial direction, toward the outside, away from the central axle of the tool, and during this process acts against a slanted surface formed on the support shoulder, in each instance.

2. The tool according to claim 1, wherein the two support shoulders mounted on the central axle in an axially displaceable manner, and, during use, have a force applied to them in the direction of the friction shoulder arranged most closely adjacent to them, by means of the setting device, in each instance.

3. The tool according to claim 2, wherein the support shoulders, during use, jointly have the force applied to them that is directed against the friction shoulder arranged most closely adjacent to them, in each instance, by means of the setting device arranged between them.

4. The tool according to claim 1, wherein the central axis is composed of two or more parts that are coupled with one another in a torque-proof manner.

5. The tool according to claim 1, wherein at least one of the support shoulders is coupled with the central axle a torque-proof manner.

6. The tool according to claim 1, wherein at least one of the friction shoulders is coupled with the central axle in a torque-proof manner.

7. The tool according to claim 1, wherein the friction shoulders, the support shoulders, and the setting device are oriented coaxially with reference to the central axle.

8. The tool according to claim 1, wherein the end faces of the friction shoulders, which face one another, are ring-shaped.

9. The tool according to claim 1, wherein the support shoulders are shaped as ring disks.

10. A method for producing panels that are composed of two panel elements pre-fabricated from a weldable material, which elements each have a recess that extends in the manner of a channel on side surfaces that are assigned to one another, comprising the following work steps: making the two panel elements available; joining the panel elements in such a manner that their side surfaces, which are provided with the channel-like recesses, butt up against one another, and that a tunnel is formed by the channel-like recesses, which tunnel is delimited on its top side and its underside, in each instance, in the case of horizontal orientation of the panel elements, by material sections of the panel elements that project away sideways from the panel element, in each instance, in the manner of crosspieces, of which sections the material sections assigned to the top side butt up against one another in a first joining seam, and the material sections assigned to the underside butt up against one another in a second joining seam; friction stir welding of the panel element, in that a tool configured in accordance with claim 1 is guided, with its central axle that acts as a welding pin, along the joining seams between the panel elements, wherein the one friction shoulder acts on the free surface on the top side, and the other friction shoulder acts on the free surface on the underside of the panel elements, and wherein the support shoulders are arranged in the tunnel, and at least one of the support shoulders is pressed, by the setting device, against the surface of two material sections of the panel elements that butt up against one another, which surface faces the tunnel.

11. The method according to claim 10, wherein the support shoulders are coupled with the central axle in a torque-proof manner, so that during friction stir welding, the material sections are subjected to friction stir stress, in each instance, both from their free outer surface that faces away from the tunnel between the panel elements, as well as from their surface that faces the tunnel.

12. The method according to claim 10, wherein the panel elements consist of a light metal material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In the following, the invention will be explained in greater detail using an exemplary embodiment shown in a drawing. The figures show, schematically, in each instance:

[0041] FIG. 1 a tool according to the state of the art during welding of two horizontally oriented panel elements, in cross-section;

[0042] FIG. 2 the panel elements made available for welding, in a horizontal orientation, in a view corresponding to FIG. 1;

[0043] FIG. 3 the panel elements according to FIGS. 1 and 2, butt-joined, in a view corresponding to FIG. 1;

[0044] FIG. 4 the panel elements according to FIGS. 1 to 3, during friction stir welding by means of the tool shown in FIG. 1, in a view corresponding to FIGS. 1 to 3;

[0045] FIG. 5 a tool according to the invention, in a representation corresponding to FIG. 1.

DESCRIPTION OF THE INVENTION

[0046] The panel elements 1, 2 are pre-fabricated in a conventional manner, for example by means of extrusion, as hollow-chamber profiles, from an aluminum material known for this purpose from the state of the art. Channel-like recesses 5, 6 are formed in the side surfaces of their longitudinal sides 3, 4, in each instance, which recesses extend over the length of the longitudinal side 3, 4 in question, and are delimited, in the case of the horizontal orientation selected in the figures, on their top side and lower side, in each instance, by a material section 7a, 7b, 8a, 8b of the corresponding panel element 1, 2. In this regard, the base of the channel-like recesses 5, 6 is formed by a crosspiece 9, 10, in each instance, of the corresponding panel element 1, 2, of the side surfaces assigned to the corresponding longitudinal side 3, 4, so that the recesses 5, 6 have a U-shaped cross-sectional shape.

[0047] For welding, the panel elements 1, 2 are butt-joined (FIG. 3), in that their longitudinal sides 3, 4 are oriented to butt up against one another, in such a manner that the outer surfaces 11, 12 of the panel elements 1, 2 lie in one plane, and the end faces of their upper material sections 7a, 8a, in the case of horizontal orientation of the panel elements 1, 2, touch one another in an upper joining seam 13, and their lower material sections 7b, 8b touch one another in a lower joining seam 13b.

[0048] The recesses 5, 6 of the panel elements 1, 2 form a tunnel 14 between the panel elements 1, 2 that butt up against one another in this way, which tunnel 14 is delimited, in the case of the horizontal orientation selected in FIGS. 1-4, on its top side by the material sections 7a, 8a, and on its underside by the material sections 7b, 8b of the panel elements 1, 2.

[0049] The tool 20 shown in FIGS. 1 and 4, corresponding to the state of the art as explained initially, for friction stir welding, has a central axle 21 configured in the manner of a welding pin provided in the case of conventional friction stir welding tools, which axle is coupled to a conventionally configured rotational drive, not shown here. The rotational drive, not shown, drives the central axle 21 so that it rotates about its longitudinal axis L.

[0050] At the lower end of the central axle 21, a first friction shoulder 22 is held in a torque-proof connection with the central axle 21. A second friction shoulder 23 is also held on the central axle 21 in a torque-proof connection, offset in the longitudinal direction of the central axle 21. In this regard, the second friction shoulder 23 is equipped with a releasable setting device, not shown here, by means of which the position of the friction shoulder 23 on the central axle 21 is fixed in place. After release of its setting device, the friction shoulder 23 can be adjusted in the longitudinal direction LR of the central axle 21.

[0051] Two support shoulders 24, 25 are arranged on the central axle 21, between the two friction shoulders 22, 23. In this regard, the support shoulders 24, 25 are displaceable in the longitudinal direction LR, and mounted on the central axle 21 in a torque-proof connection.

[0052] In the case of the tool corresponding to the state of the art shown in FIGS. 1 and 4, the support shoulders 24, 25 have an elastic force applied to them by means of a setting device 26 arranged between them, which is configured as an elastic element, in the direction toward the friction shoulder 22, 23 most closely adjacent to them. For this purpose, the setting device 26 is formed by a package of plate springs 27, 28, which are oriented relative to one another in such a manner that the support shoulder 24 is pressed in the direction of the friction shoulder 22, and the support shoulder 25 is pressed in the direction of the friction shoulder 23.

[0053] The friction shoulders 22, 23, the support shoulders 24, 25, and the plate springs 27, 28 that form the setting device 26 are oriented coaxially relative to the central axle 21, and are formed, in each instance, in such a manner that the central axle 21 can be passed through them. Accordingly, ring-shaped planar contact surfaces 29, 30, 31, 32 are formed on the end faces of the friction shoulders 22, 23 and of the support shoulders 24, 25 that are assigned to one another, and the central axle 21 runs through their center.

[0054] To start friction stir welding, the tool 20 is positioned at a laterally open end of the tunnel 14 and set up so that in the case of horizontal orientation of the butt-joined panel elements 1, 2, its first friction shoulder 23 sits on the lower outer surface 12 of the panel element 1, 2, in the case of horizontal orientation of the panel elements 1, 2, and the upper friction shoulder 22 sits on the upper outer surface 11 of the panel elements 1, 2. At the same time, the support shoulders 24, 25 sit in the tunnel 14 and are pressed against the surfaces of the material sections 7a, 8a and 7b, 8b assigned to them, in each instance, which face the tunnel 14, by the setting device 26.

[0055] Subsequently, the tool 20 is driven to rotate about its longitudinal axis L by means of the rotational drive coupled with its central axle 21, and driven to move along the joining seams 13a, 13b in a continuous forward movement. The central axle 21, which now is immersed in the material of the material sections 7a, 8a; 7b, 8b that butt up against one another in the joining seams 13a, 13b, acts as a welding pin, by means of the rotation of which, and the accompanying friction, so much heat is introduced into the relevant material that this softens, mixes, and, after the tool 20 has been moved further, solidifies again, so that the panel elements 1, 2 are connected with one another by means of welding, in a non-releasable, material-fit manner. In this regard, the support shoulders 24, 25 support the material sections 7a, 8a; 7b, 8b, and ensure that proper material mixing occurs in the joining seams 13a, 13b over the entire thickness of the material sections 7a, 8a; 7b, 8b that butt up against one another in them. At the same time, the support shoulders 24, 25, just like the friction shoulders 22, 23, guarantee, at the corresponding outer surface 11, 12 of the panel elements 1, 2, that an optimally level weld seam occurs on the side of the material sections 7a, 8a, 7b, 8b assigned to the tunnel 14.

[0056] The embodiment, according to the invention, of a tool 20′ for friction stir welding, shown in FIG. 5, differs from the tool 20 with regard to the structure of its setting device 26′ and of its support shoulders 24′, 25′. All the components of the tool 20′ that agree with the corresponding components of the tool 20 in terms of their design and function are therefore provided with reference symbols that have already been used for the tool 20.

[0057] In the case of the tool 20′, the setting device 26′ is formed by balls 33 that are loosely arranged between the support shoulders 24′, 25′. In this regard, the support shoulders 24′, 25′ are provided with a conically slanted circumferential slanted surface 34, 35 on their underside; for the remainder, they are formed like the support shoulders 24, 25. This surface drops, in the case of the upper support shoulder 24′, proceeding from its inner edge assigned to the central axle 21, in the radial direction, all the way to its outer edge, at an angle ß that is the angle of the normal line N relative to the central axle 21, whereas the slanted surface 35, in the case of the lower support shoulder 25′, proceeding from its inner edge assigned to the central axle 21, rises in the radial direction, all the way to its outer edge, also at the angle ß.

[0058] During use, the support shoulders 24′, 25′ connected with the central axle 21 in a torque-proof manner, and with them the balls 33, rotate at a high speed of rotation, so the balls 33 that sit loosely between the support shoulders 24′, 25′ are driven outward in the radial direction, along the slanted surfaces 34, 35, as the result of the centrifugal forces Ff that are then in effect. Accordingly, the balls 33 exert a resulting force Fres on the slanted surfaces 34, 35, which force results from the centrifugal force Fr and a force Fx oriented axis-parallel to the central axle 21, for which the following equation applies: Fx=Ff×sin(ß)×cos(ß). As a result of the centrifugal forces Ff that occur during use, the support shoulders 24′, 35′ are thereby pressed against the surface of the material sections 7a, 8a; 7b, 8b, which surface faces the tunnel 14, with the force Fx that acts axis-parallel to the central axle 21, and thereby they support the material sections 7a, 8a; 7b, 8b during the welding process.

REFERENCE SYMBOLS

[0059] 1, 2 panel elements [0060] 3, 4 longitudinal sides of the panel elements 1, 2 [0061] 5, 6 recesses of the panel elements 1, 2 [0062] 7a, 7b in the case of horizontal orientation, upper material sections of the panel elements 1, 2 [0063] 8a, 8b in the case of horizontal orientation, lower material sections of the panel elements 1, 2 [0064] 9, 10 crosspieces of the panel elements 1, 2 [0065] 11, 12 outer surface of the panel elements 1, 2 [0066] 13a, 13b joining seams [0067] 14 tunnel formed by the recesses 5, 6 [0068] 20, 20′ tools for friction stir welding of the panel elements 1, 2 [0069] 21 central axle of the tools 20, 20′ [0070] 22, 23 friction shoulders of the tools 20, 20′ [0071] 24, 25 support shoulders of the tool 20 [0072] 24′, 25′ support shoulders of the tool 20′ [0073] 26 setting device of the tool 20 [0074] 26′ setting device of the tool 20′ [0075] 27, 28 plate springs of the setting device 26 [0076] 29-32 contact surfaces of the support shoulders 24, 25 and of the friction shoulders 22, 23 [0077] 33 balls of the setting device 26′ [0078] 34, 35 slanted surface of the support shoulders 24′, 25′ [0079] ß angle between the slanted surfaces 34, 35 and the normal line N [0080] Ff centrifugal forces that act on the balls 33 during use, oriented in the radial direction with reference to the central axle [0081] Fx forces that act on the support shoulders 24′, 25′ during use, in the axial direction [0082] Fres force exerted on the slanted surfaces 34, 35 by the balls 33 during use [0083] L longitudinal axis of the central axle 21 [0084] LR longitudinal direction of the central axle 21 [0085] N normal line relative to the central axle 21