BONDING OBJECTS TOGETHER

Abstract

A method of bonding together a first object and a second object having a flat part and an opening defining a contour is provided. The second object has a fastening portion having a coupling structure defining an undercut and running around a periphery of the opening. The method includes positioning the first object relative to the second object in the opening, and providing a thermoplastic material along the contour, causing a relative force between the second and first objects and impinging the assembly of the first and second object with mechanical vibration until at least a flow portion of the thermoplastic material becomes flowable and flows into the coupling structure, and causing the thermoplastic material to re-solidify.

Claims

1. A method of bonding a first object to a second object, comprising, providing the second object having a flat part, and an opening defining a contour, the second object having a fastening portion defining having a positive fit shape with an undercut and running around a periphery of the opening, providing the first object, positioning the first object relative to the second object in the opening, and providing a thermoplastic material along the contour, causing a relative force between the second and first objects and impinging the assembly of the first and second object with mechanical vibration until at least a flow portion of the thermoplastic material becomes flowable and flows into the coupling structure, and causing the thermoplastic material to re-solidify.

2. The method according to claim 1, wherein the first object comprises the thermoplastic material.

3. The method according to claim 1, wherein the step of causing a relative force between the second and first objects and impinging the assembly of the first and second object with mechanical vibration comprises using a sonotrode to press the first object against the second object, wherein a coupling face of the sonotrode is in contact with a coupling face of the first object.

4. The method according to claim 1, wherein the step of causing a relative force between the second and first objects and impinging the assembly of the first and second object with mechanical vibration is carried out by a sonotrode having a distal end shape following the contour.

5. The method according to claim 1, wherein the step of causing a relative force between the second and first objects and impinging the assembly of the first and second object with mechanical vibration is carried out using a gliding sonotrode or rolling sonotrode that moves in a controlled fashion around the contour.

6. The method according to claim 1, wherein the step of causing a relative force between the second and first objects and impinging the assembly of the first and second object with mechanical vibration is carried out sequentially for different locations around the contour.

7. The method according to claim 1, wherein the step of causing a relative force between the second and first objects and impinging the assembly of the first and second object with mechanical vibration is carried out until the coupling structure is uninterruptedly penetrated by the thermoplastic material along the entire contour.

8. The method according to claim 1, wherein the flat part along the contour is folded towards a proximal side and/or away from the opening to form at least a part of the coupling structure.

9. The method according to claim 1, wherein the second object is shaped to form a pot-like feature around the opening, with the flat part being bent towards a distal side and forming an interior wall portion, with the sheet metal continuing into a fastening portion following an inner end of the wall portion, the fastening portion forming the coupling structure.

10. The method according to claim 9, wherein in the step of positioning, the first object is positioned with a gap between a peripheral surface and the interior wall portion.

11. The method according to claim 1, wherein the flat part is a metal sheet portion.

12. The method according to claim 1, wherein the first object has a peripheral flange, and wherein in the step of causing a relative force between the second and first objects and impinging the assembly of the first and second object with mechanical vibration, the peripheral flange is in contact with the coupling structure.

13. The method according to claim 1, wherein the second object belongs to an automobile body.

14. A method of fixing a first object to a second object, the method comprising the steps of: providing the second object with a plurality anchors fastened thereto, wherein each anchor comprises an end piece with a surface portion that has a coupling structure with an undercut, providing the first object comprising thermoplastic liquefiable material in a solid state, pressing the first object against the second object with mechanical vibration acting on the first object and/or the second object until a flow portion of the thermoplastic material of the first object is liquefied and flows into the coupling structures of the end pieces, and letting the thermoplastic material of the first object re-solidify to yield a positive-fit connection between the first and second objects by the liquefied and re-solidified flow portion interpenetrating the coupling structures.

15. The method according to claim 14, the second object being sheet-like.

16. The method according to claim 14, wherein the step of pressing the first object against the second object with mechanical vibration acting on the first object and/or the second object is carried out sequentially for the different end pieces.

17. The method according to claim 14, wherein the step of pressing the first object against the second object with mechanical vibration acting on the first object and/or the second object is carried out simultaneously for at least some of the end pieces.

18. The method according to claim 17, wherein the step of pressing the first object against the second object with mechanical vibration acting on the first object and/or the second object is carried out using a sonotrode with a large coupling surface covering a plurality of end pieces, the sonotrode acting on the first object or on the second object.

19. The method according to claim 14, wherein the anchors each comprise two anchor parts, an anchoring part and an end piece part comprising the end piece, wherein the two anchor parts are reversibly detachable from each other.

20. The method according to claim 19, wherein the end piece part is a click-on part capable of being reversibly clicked on the anchoring part.

21. The method according to claim 14, wherein pressing the first object against the second object with mechanical vibration acting on the first object and/or the second object comprises coupling the mechanical vibration into the first object by a sonotrode.

22. The method according to claim 21, wherein during the step of pressing the first object against the second object with mechanical vibration acting on the first object the sonotrode presses against the first object, optionally with an intermediate piece between the sonotrode and the first object.

23. The method according to claim 14, wherein during the step of pressing the first object against the second object with mechanical vibration acting on the first object and/or the second object, portions of the first object between different end pieces remain solid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Hereinafter, principles and embodiments of the invention are illustrated in drawings. All drawings are schematical and not to scale. The drawings are used to explain the invention and embodiments thereof and are not meant to restrict the scope of the invention. In the drawings, same reference numbers refer to same or analogous elements. Terms designating the orientation like proximal, distal, etc. are used in the same way for all aspects and drawings. The drawings show:

[0072] FIGS. 1a and 1b a process according to the first aspect of the invention;

[0073] FIG. 2 a possible application illustrating a three-dimensional shape of the contour

[0074] FIGS. 3-6 alternative configurations along the contour in section;

[0075] FIGS. 7a and 7b the process according to the second aspect of the invention;

[0076] FIG. 8 a configuration with four fastening locations; and

[0077] FIGS. 9a and 9b a possible application of the second aspect of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0078] FIGS. 1a and 1b illustrate an example of the process according to its first embodiment. The figures show a cutaway section along a periphery of the opening 20 in the second object (sheet metal) 2 in which the first object 1 is fastened. The first object comprises, at least along the periphery, thermoplastic material, for example PVC.

[0079] The upper side in the figure is the exterior (and proximal) side, and the lower side is the interior/distal side. The sheet metal that forms the second object 2 in the depicted embodiment is a sheet metal portion of a complex object, the sheet metal having an outer face portion 21, a wall portion 22 and a fastening portion 23 that comprises, by having a bent-back-outwardly-section a shape that forms a coupling structure.

[0080] The first object here is a PVC carrier structure for accommodating a functional element.

[0081] The figures show that there is a gap 7 between the wall portion 22 and a first object outer peripheral portion (for example for dealing with different thermal behaviour). The flexibility of the connection brought about by a resilience of the metal sheet second object and/or resilience of the thermoplastic or other material of the first object can take up variations of the gap size over time while maintaining a tight seal.

[0082] A sonotrode 6 is used to press a peripheral portion 11 against the fastening portion 23 while mechanical vibration is coupled into it. By the absorption of the mechanical vibration energy, a flow portion of the thermoplastic material of the first object becomes flowable and flows relative to the second object 2.

[0083] FIG. 1b, showing the assembly after the flow portion has become flowable, illustrates how the mechanical vibration causes the thermoplastic material (flow portion 12) of the first object object (e.g. PVC) to melt around the fastening portion 23. A material flow may be controlled by the shape of the metal sheet, the flow portion 12 volume by a vertical movement of the sonotrode 6 and by the first object edge design (the design along the contour).

[0084] A main idea of embodiments of the first aspect is thus to use the material of the first object itself to flow into a mechanical locking shape provided by the sheet metal.

[0085] Depending on the first object design, the sonotrode can be placed on the edge of the first object (as shown in FIG. 1a) or inside the first object.

[0086] In embodiments, the first object has a peripheral flange 15 that belongs to the peripheral portion, and the sonotrode at least partially impinges on the flange 15 during the process, whereby the flange is clamped between the sonotrode and the second object. The flow portion may at least partially be of material from such a peripheral flange 15.

[0087] As mentioned, instead of using a gliding sonotrode (as shown) or rolling sonotrode that moves in a controlled fashion around the contour melting the polymer in the contact spot as it moves, it would also be possible to use a sonotrode having a shape that follows the contour around the whole periphery of the first object and is attached to a suitable vibration source.

[0088] In embodiments of the first variant (gliding or rolling sonotrode), a separate pressing tool following the sonotrode may be used to maintain the pressing force for some time when the sonotrode has moved on. Such pressing tool may for example follow the sonotrode on its path around, for example by having a fixed position relative thereto, or it may have a variable position relative thereto.

[0089] In embodiments, the process of making the flow portion flowable may include moving back and forth the gliding or rolling sonotrode several times.

[0090] FIG. 2 depicts a complex article 30, for example a control station, of which the second object 2 is a part. The first object 1 in the depicted example is a touch screen input device that has plastic frame and has a 3D-shape for example for optical reasons. Generally, the second object may have a complex three-dimensional shape so that the contour 31, which is a closed contour in FIG. 2, follows an accordingly complex three-dimensional path.

[0091] FIG. 3 shows a variant in which a proximal face of the first object after the fastening process is approximately flush with a surface defined by the second object. In this variant, the first object 1 may for example be a window, a cover or other object closing off the opening.

[0092] FIG. 4 shows a configuration similar to the embodiment of FIG. 1a, however, the fastening portion 23 has a different shape with an edge portion 25 projection towards proximally and thereby serving as an energy director. More distal portions of the fastening portion define the undercut.

[0093] FIG. 5 shows yet another configuration in which the fastening portion 23 has a more complex cross section with energy directing ridges 26. In contrast to the other embodiments of the first aspect, the fastening portion is not only constituted by a folded edge section of the second object. Rather, the ridges 26 project from flat sections. A second object 2 of this kind may for example be produced by casting techniques or by welding metal sheet portions together.

[0094] Another feature of the embodiment of FIG. 5 is independent of the shape of the fastening portion and may be an optional feature of any embodiment of the first aspect and also of the second aspect described hereinafter. Namely, the first object does not consist of the thermoplastic material but includes in addition to a thermoplastic portion 15 also a non-liquefiable portion 14 of a different material composition (non-liquefiable in the present text means not liquefiable under the conditions that are sufficient for liquefying the thermoplastic material that contributes the flow portion, non-liquefiable material may include a metal, a ceramic, a plastic material that is not thermoplastic or a thermoplastic with a melting or glass transition temperature substantially higher than the corresponding temperature of the flow portion.

[0095] FIG. 6 shows yet another configuration in which the fastening portion 23 is folded back to be supported by itself, so that a ridge is formed that projects towards the proximal side and has energy directing characteristics. The flow portion may flow into an interior of the folded back portion through openings 27, which may for example be arranged regularly along the contour.

[0096] FIG. 7a illustrates a set-up for an embodiment of the second aspect of the invention. The anchor 51 has an anchoring part 54 anchored in an opening of the second object 2 and a removable click on part 52. The removable click on part 52 includes an end piece 53 with a coupling structure that in the shown embodiment is barb-like. In the figure, the end piece 53 is shown to be metallic and embedded in plastic material of the click on part 52; however the click on part could also be one-piece, for example one-piece metallic.

[0097] For the process, the first object 1 can be moved (double arrows) to take up any tolerance and for its position to be optimized for example from an aesthetical point of view (such as adjusted to hatch door frame regarding visual gap). Then mechanical vibration acts on the first object or possibly the second object until the flow portion becomes flowable and flows into the structure to soundly connect the end piece to the first object 1. A paint/lacquer protection 41 may be applied between the sonotrode 6 and the first object 1 if the outer surface of the first object is visual in the end product (this option applying to all embodiments of all aspects of the invention if necessary or advisable).

[0098] FIG. 7b shows the resulting situation. Removing of the panel is possible by clicking off the click on part.

[0099] This approach features the advantage that positioning of the anchors does not need to be precise, and nevertheless visual precision of the fastening is possible.

[0100] This is illustrated for example in FIG. 8, where a second object 2 with a plurality of fastening locations 70 is shown, each fastening location for example defined by an anchor attached to the second object. The positions of the fastening locations neither need to be very precisely defined (and hence may vary to a certain extend from article to article in a series of articles), nor need they be exactly known. A first object is placed relative to the second object and thereby may be positioned in an exact relationship with other features of the second object than the fastening location, for example features that remain visible when the first object is placed relative to the second object and thereby covers the fastening locations.

[0101] FIGS. 9a and 9b illustrate an application, with the dimensions of the anchors and the thickness of the second object being shown exaggeratedly to better illustrate the invention.

[0102] A complex article 30 includes the second object 2 that carries the anchors, each including an anchoring part 54 anchored relative to the second object 2 and a click-on part 52 clicked on the anchoring part. The first object 1 here has a plate shape. It may for example be a plastic carrier structure for a further element. For the process of fixing the first object to the second object 2, the click-on parts are clicked on the anchoring parts, and at least one sonotrode 6 is used to impinge the first object with a pressing force and mechanical energy (FIG. 9a).

[0103] After the fixing process, the positions of the click-on parts are defined by their being anchored in the first object, and the first object is thereby reversibly removable by releasing the click-on connection (FIG. 9a).