CONNECTING ELEMENT FOR THE NON-DETACHABLE CONNECTION OF AT LEAST TWO COMPONENTS AND COMPOSITE ARRANGEMENT

Abstract

The present invention relates to a connecting element for non-detachably connecting at least two components by means of friction welding when the connecting element is rotated about a longitudinal axis of the connecting element. The connecting element includes a stem formed along the longitudinal axis with a stem face at a free end of the stem for penetrating at least one component, and a head connected to the stem for transmitting a torque about the longitudinal axis from a turning tool to the stem. The stem face has a stem end face which has a convex envelope with a blunt shape.

Claims

1. A connecting element for non-detachably connecting at least two components by means of friction welding when the connecting element is rotated about a longitudinal axis of the connecting element, comprising: a stem formed along the longitudinal axis with a stem face at a free end of the stem for penetrating at least one component, and a head connected to the stem for transferring a torque about the longitudinal axis from a rotary tool to the stem wherein the stem face has a stem end face which has a convex envelope with a blunt shape.

2. The connecting element according to claim 1, further comprising at least one of the following features: wherein the stem end face has a plurality of recesses and projections; wherein the stem end face is configured as a golf ball shape.

3. The connecting element according to claim 1, wherein the convex envelope of the stem end face has a round or arc-shaped outline in a longitudinal section plane.

4. The connecting element according to claim 1, further comprising at least one of the following features: wherein the stem comprises a mold section starting from the free end of the stem and a retaining section starting from the head of the stem; wherein the mold section has a polygon-shaped outline with rounded corners in a cross-sectional plane; wherein the polygonal-shaped outline of the mold section has at least three corners; and wherein the retaining section has a diameter that is larger than a maximum diameter of the mold section.

5. The connecting element according to claim 4, wherein the mold section has an outline in the cross-sectional plane which is regionally alternately rectilinear and arc-shaped.

6. The connecting element according to claim 4, further comprising at least one of the following features: in each case a flat surface section of the mold section is polygon-shaped, wherein in each case one polygon is preferably triangular or quadrangular; an outer surface of the mold section is profiled about the longitudinal axis in a circumferential direction of the mold section; the outer surface of the mold section is tripolygonal in shape; the outer surface of the mold section i) has radial grooves, notches or depressions or ii) is smooth.

7. The connecting element according to claim 4, further comprising at least one of the following features: the retaining section is cylindrical or approximately cylindrical or conical; a transition between at least i) the stem face and the mold section or ii) between the mold section and the retaining section is of rounded configuration.

8. The connecting element according to claim 1, further comprising at least one of the following features: the a bottom of the head facing the stem has a circumferential groove; an upper side of the head facing away from the stem has a torque coupler for transmitting the torque from the rotary tool to the head; wherein the torque coupler comprises a plurality of radial grooves, recesses or projections.

9. The connecting element according to claim 4, further comprising at least one of the following features: wherein the connecting element is formed from a steel alloy, preferably from a screw tempering material; wherein at least the stem end face is electrogalvanized; a length of the mold section is about two to three times smaller than a length of the stem.

10. The connecting element according to claim 1, wherein the connecting element, except for the stem end face, is electroplated.

11. A composite arrangement comprising: at least two components and at least one connecting element for non-detachably connecting at least two components by means of friction welding when the connecting element is rotated about a longitudinal axis of the connecting element, comprising a stem formed along the longitudinal axis with a stem face at a free end of the stem for penetrating at least one component, and a head connected to the stem for transferring a torque about the longitudinal axis from a rotary tool to the stem, wherein the stem face has a stem end face that has a convex envelope with a blunt shape by which the components are non-detachably connected by means of friction welding.

12. The composite arrangement according to claim 11, further comprising at least one of the following features: a respective component is formed from a metal or a metal alloy; at least one of the components, is formed from a material which comprises at least a non-ferrous metal, preferably copper, aluminum or brass or has a lower material hardness than the connecting element; at least one of the components not arranged as first components is made from steel; a total thickness of the components is at most as great as a length of a retaining section of the connecting element.

13. The connecting element according to claim 2, wherein the convex envelope of the stem end face has a round or arc-shaped outline in a longitudinal section plane.

14. The connecting element according to claim 9, further comprising a layer of a material comprising zinc or a zinc-nickel compound that is electrochemically applied at least to the stem end face.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Connecting elements according to the invention are explained in more detail below on the basis of drawings. They each show schematically:

[0062] FIG. 1 shows a first embodiment of the connecting element in a side view.

[0063] FIG. 2 shows a first embodiment of the connecting element in a top view.

[0064] FIG. 3 shows a first embodiment of the connecting element in a bottom view.

[0065] FIG. 4-7 shows the processing steps of a composite arrangement with two components and a composite element by friction welding.

[0066] FIG. 8 the first embodiment of the connecting element in a longitudinal sectional plane sectional view through the stem face.

[0067] FIG. 9 the first embodiment of the connecting element in a cross-sectional plane sectional view through the stem face.

[0068] FIG. 10 a second embodiment of the connecting element in a cross-sectional plane section view through the stem face.

[0069] FIG. 11 shows a third embodiment of the connecting element in a side view.

[0070] FIG. 12 a third embodiment form of the connecting element in cross-sectional plane section views through the retaining section and the forming section.

[0071] FIG. 13 a third embodiment of the connecting element in a longitudinal sectional plane sectional view.

[0072] Elements with the same function and mode of operation are each provided with the same reference signs in the FIGS. 1 to 13 shown.

DETAILED DESCRIPTION

[0073] FIG. 1 shows a first embodiment of connecting element 10, which is used for the non-detachable connection of two components 12.1, 12.2 by friction welding, which is used in the FIG. 4-7, when turning the connecting element 10 around a longitudinal axis 10.1 of the connecting element 10.

[0074] The connecting element 10 comprises: [0075] a stem 10.2-10.4 formed along the longitudinal axis 10.1 with a stem face 10.2 at a free end of the stem 10.2-10.4 for penetrating a component 12.1, and [0076] a head 10.5 connected to the stem 10.2-10.4 to transmit a torque about the longitudinal axis 10.1 from a turning tool to the stem 10.2-10.4.

[0077] The stem face 10.2 has a stem end face 10.21 which has a convex envelope 10.22 with a blunt course. The envelope 10.22 of the stem end face 10.21 is to be understood as a surface which envelops the stem end face 10.21 and whose points connect relative maxima of the stem end face 10.21 (see FIG. 8-10). The relative maxima form points of a 2D interpolation surface connecting the relative maxima or points, which represents the envelope 10.22.

[0078] In the front view of the connecting element 10 shown in FIG. 1 the envelope 10.22 corresponds to a contour of the stem end face 10.21. In contrast to this, in the sectional views of the stem face 10.2 shown in FIGS. 8 and 9, the envelope 10.22 differs from the contour 10.21 of the stem face 10.2 and is thus clearly recognizable.

[0079] In the plan view of the connecting element 10 shown in FIG. 2, the head 10.5 is recognizable, whereby an upper side of the head 10.5 facing away from the stem 10.2-10.4 has a circular flat pressure surface 10.53 in its center and a torque coupler 10.52 around it on the outside for transmitting the torque from a turning tool to the head 10.5 during friction welding. The torque coupler comprises radial grooves or recesses 10.52 in which a corresponding counterpart of the turning tool (not shown), for example radial projections of a face of the turning tool, cooperates with the torque coupler or engages in the radial grooves when the turning tool is lowered axially to turn the connecting element 10. The flat pressure surface 10.53 is provided for axial pressure on the connecting element 10.

[0080] In the view from below of the connecting element 10 shown in FIG. 3, the stem end face 10.21 is visible, which has crests or projections 10.23 and troughs or depressions 10.24, which form friction-increasing elements of the stem end face 10.21.

[0081] The stem end face 10.21, shown as an example in FIGS. 8, 9, has a blunt shape in that it is not pointed or angular. In other words, the stem end face 10.21 can be represented or shown in the longitudinal section plane (FIG. 8) or cross-section plane (FIG. 9) by a continuous function, the first derivative of which is continuous between the edges of the function, which are also edges of the stem end face 10.21.

[0082] FIG. 8 shows in a longitudinal sectional plane sectional view through the stem face 10.2 a first formation of the stem end face 10.21 with friction increasing elements. Here it can be seen that the contour 10.21 of the stem face 10.2 has a plurality of projections or wave crests 10.23 and of depressions or wave valleys 10.24 which are evenly distributed. In FIG. 9, in which in a cross-sectional plane sectional view through the stem face 10.2 the contour of the stem face 10.2 or the stem end face 10.21 is shown, similar friction increasing elements (uniformly distributed projections 10.23 and depressions 10.24) are recognizable. In general, the stem end 10.2 has a wave-shaped contour 10.21 in sectional views through the stem end 10.2, whereby the height or amplitude of the wave is exaggerated in the figures shown for illustrative purposes, i.e. greater than according to a real scale.

[0083] FIG. 10 shows in a longitudinal sectional plane sectional view through the stem end 10.2 a further formation of the stem end face 10.21 with friction-enhancing elements. In this embodiment the contour 10.21 of the stem face 10.2 shows an undulating course with a rectangular shape, whereby the corners are cut off or blunt.

[0084] The embodiment of the connecting element 10 shown in FIGS. 8-10 have a substantial friction welding effect due to the blunt course of the stem end face 10.21 and/or the envelope 10.22 in conjunction with the stem face 10.2, which has a surface structure with friction-enhancing elements 10.23, 10.24. A similar effect (friction, heating, material melting, no waste generation) is also produced by a (not shown) golf ball structure of the stem end face 10.21.

[0085] In the side view of the connecting element 10 shown in FIG. 11, it can be seen that the stem 10.2-10.4 comprises a mold section 10.3 starting from the free end of the stem and a retaining section 10.4 starting from the head 10.5 of the stem. The retaining section 10.4 thus forms an upper part of the stem which holds the head 10.5, and the mold section 10.3 forms a lower part of the stem which adjoins the stem face 10.2 and, together with the stem face 10.2, contributes to the generation of increased friction between the connecting element 10 and components 12.1, 12.2 and thus to an increased friction welding effect.

[0086] The stem face 10.2 shown in FIG. 11, 13 has a blunt stem end face 10.21 without a wave-like shape, but with a fine-grained, friction-enhancing surface structure which produces the desired effect of an improved friction welding.

[0087] The retaining section 10.4 shown in FIG. 11 has a larger diameter than a maximum diameter of the mold section 10.3. This has the advantage that a hole (through bore) created or spread out in the first component 12.1 during friction welding or a pilot hole created in the second component 12.2 after completion of the friction welded connection is reliably sealed by the retaining section 10.4 starting from the head 10.5. In contrast to this, the connecting element 10 shown in FIG. 1 has a stem 10.2-10.4 in which the mold section 10.3 and the retaining section 10.4 do not or only slightly differ from each other.

[0088] In the cross-sectional plane sectional views through the retaining section 10.4 (section A-A) and through the mold section 10.3 (section B-B) shown in FIG. 12, it can be seen that the retaining section 10.4 has a cross-section with a circular contour 10.41 and the mold section 10.3 has a cross-section with a contour 10.31 which is not circular but slightly undulating. The cross-sectional contour 10.31 of the mold section 10.3 is friction-increasing and thus improves the friction welding and reduces the cycle times. In addition, it can be seen that the largest diameter of the forming section contour 10.31 is larger than the diameter of the retaining section contour 10.41. Thus, after the production of a friction welded connection, the outer circumference of the mold section 10.3 lies flat against the surge of a hole produced in the upper component 12.1 and thus ensures a reliable sealing of the friction welded connection produced.

[0089] In the longitudinal sectional plane sectional view through the connecting element 10 shown in FIG. 13, the overall structure of the connecting element 10 is visible. The stem 10.2-10.4 formed along the longitudinal axis 10.1 has a curved and blunt stem face 10.2 and is connected with a head 10.5. The stem 10.2-10.4 has a mold section10.3 in a lower part connected to the stem face 10.2 and a retaining section 10.4 in an upper part connected to the head 10.5. The bottom of the head 10.5 facing the stem 10.2-10.4 has a circumferential groove 10.51. This configuration corresponds to a chamfer and makes it possible, advantageously during friction welding, to accommodate molten component material so that an outer edge on the bottom of the head 10.5 rests flat on the upper 12.1 of the interconnected components 12.1, 12.2 and additionally seals the friction welded connection against moisture penetration.

[0090] In the case of the FIG. 4-7, the connecting element 10 is first turned by rotation and axial pressure into a first component 12.1 (FIG. 4), which consists of aluminum, moved through it and pressed into a following, second component 12.2 made of steel without penetrating it (FIG. 5). Due to the friction created by the turning and pressing in, the connecting element 10 and the contacted, surrounding component material become hot, whereby the flow stress of the component material is lowered and the material is displaced by the connecting element 10 (FIG. 6), so that the connecting element 10 is bonded to the components 12.1, 12.2, while the components 12.1, 12.2 are held in contact with each other. The molten component material rises up the side of the connecting element 10 and penetrates into the circumferential groove 10.51 on the bottom of the head 10.5. Finally, by means of rotation and axial pressure, a compression of the stem 10.2-10.4 is effected, bringing the head 10.5 of the connecting element 10 into an end position on the first component 12.1 (FIG. 7).

LIST OF REFERENCE SIGNS

[0091] 10 Connecting element [0092] 10.1 Longitudinal axis of the connecting element [0093] 10.2 Stem face of the connecting element [0094] 10.21 Stem end face, contour of the stem face [0095] 10.22 Envelope of the stem end face or stem face [0096] 10.23 Projections, crest of stem end face or stem face [0097] 10.24 Recess, trough of stem end face or stem face [0098] 10.3 Mold section of the connecting element [0099] 10.31 Contour of the mold section [0100] 10.4 Retaining section of the connecting element [0101] 10.41 Contour of the retaining section [0102] 10.5 Head of the connecting element [0103] 10.51 Circumferential groove at the bottom of the head [0104] 10.52 Torque coupler, radial groove on top of head [0105] 10.53 Pressure surface on top of the head [0106] 12.1 First component to be connected [0107] 12.2 Second component to be connected