EXPANSION ELEMENT

Abstract

A sheet-like textile is used for a controlled expansion of an expansion element on a structural element in a vehicle body. The sheet-like textile is covered with an expandable material on both sides. The expansion of the expansion element in a direction perpendicular to the sheet-like textile is at least 15% greater than what it would be for an expansion element without a sheet-like textile.

Claims

1. A method comprising: applying a sheetlike textile for the controlled expansion of an expansion element on a structural element in a vehicle body, the sheetlike textile being covered on both sides with expandable material, and expanding the expansion element; wherein the expansion of the expansion element in a direction perpendicular to the sheetlike textile is greater by at least 15% than would be the case for an expansion element without sheetlike textile.

2. The method as claimed in claim 1, wherein the sheetlike textile is a mesh.

3. The method as claimed in claim 1, wherein the sheetlike textile has a basis weight of between 5 and 500 g/m.sup.2.

4. The method as claimed in claim 1, wherein the sheetlike textile has a thickness of between 10 and 1000 μm.

5. The method as claimed in claim 1, wherein the sheetlike textile has a mesh size of between 1 and 10 mm.

6. The method as claimed in claim 1, wherein fibers of the sheetlike textile have multidirectional orientation.

7. The method as claimed in claim 1, wherein the sheetlike textile substantially does not influence a tensile strength of the expansion element in a cured state.

8. The method as claimed in claim 1, further comprising: curing the expandable material and crosslinking the expanded material through the sheetlike textile.

9. The method as claimed in claim 1, wherein the sheetlike textile comprises at least one or more of the following materials: glass fiber, carbon fibers, or polymeric fibers.

10. The method as claimed in claim 1, wherein two to five sheetlike textiles are applied.

11. A method for joining two structural elements of a vehicle body with an expansion element, the method comprising: providing an expandable material; providing a sheetlike textile; forming an expansion element comprising the expandable material and the sheetlike textile, the sheetlike textile being covered on both sides with expandable material; and expanding the expansion element, wherein an expansion of the expansion element in a direction perpendicular to the sheetlike textile is at least 15% greater than would be the case for an expansion element without sheetlike textile.

12. The method as claimed in claim 11, wherein the method further comprises: adhering the expansion element on one of the structural elements.

13. The method as claimed in claim 12, wherein the expandable element is tacky at room temperature, wherein the expansion element is detached from a carrier element before it is disposed on the structural element, and wherein the expansion element has a handling foil on one side.

14. The method as claimed in claim 12, wherein the expandable material is not tacky at room temperature, and wherein the expansion element has an adhesive film on one side for adherence on the structural element.

15. The method as claimed in claim 11, wherein the method comprises extruding the expandable material when the expansion element is formed.

Description

[0057] Details and advantages of the invention are described below using exemplary embodiments and with reference to schematic drawings.

[0058] In the drawings:

[0059] FIGS. 1a to 1c show schematic representation of an expansion element;

[0060] FIGS. 2a and 2b show schematic representation of an expansion element in a cavity of a structural element; and

[0061] FIG. 3 shows illustrative cross sections of expanded expansion elements from the series of experiments of table 1.

[0062] FIGS. 1a to 1c represent various exemplary embodiments of expansion elements 1.

[0063] In this case the expansion elements 1 are each shown in a cross-sectional representation. Each expansion element 1 comprises expandable material 2 and one or more sheetlike textiles 3. A total thickness 7 of the expansion element 1 is divided here by the sheetlike textiles 3 into individual layers, with each of the layers having a layer thickness 6. In all three exemplary embodiments, a smallest layer thickness 6 of the expansion element 1 is designed in each case such that it amounts to at least 10% of the total thickness 7 of the expansion element 1.

[0064] In the three exemplary embodiments represented, the sheetlike textiles 3 are disposed in each case symmetrically in the expansion element 1. In an alternative exemplary embodiment not represented, however, the sheetlike textiles 3 may also be disposed nonsymmetrically.

[0065] In FIGS. 2a and 2b an expansion element 1 is disposed in a cavity 5 of a structural element 4. FIG. 2a here shows the expansion element 1 in an unexpanded state, and FIG. 2b shows the same expansion element 1′ in an expanded state.

[0066] In this representation it can be seen that through the provision of a sheetlike textile 3 between layers of expanded material 2, increased expansion in a direction perpendicular to the sheetlike textile 3 is achieved, thereby making it possible to close an existing gap between two substantially opposite structural elements using a relatively small expansion element 1.

[0067] In FIG. 2b it is apparent that the expanded material 2′, especially in the vicinity of the sheetlike textile 3 and in the vicinity of the structural elements 4, expands to less of an extent in directions along the plane of the sheetlike textile 3 than would be the case without an attachment to the sheetlike textile 3 and to the structural element 4, respectively. As a result of this effect, there is increased expansion perpendicularly to the plane of the sheetlike textile 3.

[0068] Table 1 below represents an illustrative experimental series of illustrative expansion elements. In these experiments, different expandable materials and also different sheetlike textiles (and also a comparative experiment with an aluminum foil rather than a sheetlike textile) are employed.

[0069] Expandable materials used were SikaReinforcer®-604 (denoted SR-604) and also SikaBaffle®-235 (denoted SB-235).

[0070] Sheetlike textiles employed were polyester mesh, woven glass fiber fabric, and woven carbon fiber fabric. In these contexts, experiments with a sheetlike textile, experiments with two sheetlike textiles, and reference experiments without sheetlike textiles were carried out.

[0071] Additionally, an experiment with an aluminum foil rather than a sheetlike textile was carried out (sample R1a).

TABLE-US-00001 TABLE 1 Increase in height Relative Expand. Number and nature to the Sample Material of sheetlike textile Factor reference RR SR-604 Reference (no textile) 2.01 ± 0.01 R1p SR-604 . . . with 1 polyester mesh 2.51 ± 0.03 25% R1g SR-604 . . . with 1 glass fiber fabric 2.43 ± 0.03 21% R1c SR-604 . . . with 1 carbon fiber fabric 2.50 ± 0.03 24% R1a SR-604 . . . comparative experiment 2.26 ± 0.01 12% with 1 aluminum foil RR SR-604 Reference (no textile) 2.13 ± 0.01 R2p SR-604 . . . with 2 polyester meshes 2.92 ± 0.07 37% R2g SR-604 . . . with 2 glass fiber fabrics 2.59 ± 0.07 22% R2c SR-604 . . . with 2 carbon fiber fabrics 2.54 ± 0.05 19% BR SB-235 Reference (no textile) 3.61 ± 0.11 B1p SB-235 . . . with 1 polyester mesh 5.14 ± 0.02 42% B2p SB-235 . . . with 2 polyester meshes 6.00 ± 0.13 66%

[0072] First of all it is apparent from the experimental series that the sheetlike textiles have a significant influence on the increase in height when the expansion element is expanded.

[0073] Furthermore, it was found that sheetlike textiles produce a greater increase in height than is the case with foils. The comparative experiment with aluminum foil produced a height increase of 12% relative to the reference without sheetlike textile, whereas all of the experiments with sheetlike textiles produced an increase in height of at least 15%.

[0074] The result of the comparative experiment with aluminum foil is additionally confirmed by the aforementioned WO2011/109699A1, in which table 2, with reinforcing foils in the four examples A to D, found the following values for the percentage increase in height in comparison to the reference example: example A−3%, example B+8%, example C+12%, and example D+14%.

[0075] From this experimental series it is apparent, moreover, that the greater the number of sheetlike textiles used, the greater the expansion perpendicular to the plane of the sheetlike textile, referred to as increase in height in the table. For instance, when using two sheetlike textiles, the expansion in this direction is greater than when using one sheetlike textile, and when using a sheetlike textile the expansion in the desired direction is greater than for the reference example without sheetlike textile.

[0076] FIG. 3 depicts three illustrative cross sections from the experimental setup represented in table 1. This FIG. 3 shows the three lowermost experiments of the experimental setup according to table 1 (samples BR, B1p and B2p). In this representation of cross sections of the resulting samples as well, the effect of the sheetlike textiles 3, in improving an expansion in a direction perpendicular to the sheetlike textiles 3, is apparent.

[0077] In FIG. 3, the position of the sheetlike textiles 3 (polyester meshes in this exemplary embodiment) has been indicated with dashed lines, since the textiles would be otherwise invisible because of the proportions and the contrasts.

LIST OF REFERENCE NUMERALS

[0078] 1—expansion element in unexpanded state [0079] 1′— expansion element in expanded state [0080] 2—expandable material [0081] 2′—expanded material [0082] 3—sheetlike textile [0083] 4—structural element [0084] 5—cavity [0085] 6—layer thickness [0086] 7—total thickness