Method for producing a securing arrangement and securing arrangement

Abstract

A method of producing fastening assembly (10) including a series of layers (12, 14, 16) and a screw (18), the screw (18) having a screw head (20), a shaft (24), a thread (26) extending into a displacement tip (22) and an unthreaded shaft portion (28). The method includes screwing the screw (18) into the series of layers (12, 14, 16), the layer (14) in the series of layers (12, 14, 16) that is furthest from the screw head (20) being deformed in the screw-in direction, so that a thickness D.sub.p of the series of layers (12, 14, 16) is increased in a region around the screw (18), and continuing to screw in the screw (18) until the screw head (20) strikes the series of layers, a maximum thickness D.sub.p, max of the series of layers being reached at this moment and the length L.sub.F of the unthreaded shaft portion (28) being up to 10% less than and up to 30% greater than the maximum thickness D.sub.p, max of the series of layers.

Claims

1. A method for producing a fastening assembly (10) comprising a series of solid layers (12, 14, 16) that are in contact with one another and a screw (18), the screw (18) comprising a screw head (20) equipped with a driving point, a shaft (24) extending into a displacement tip (22), a thread (26) extending into the displacement tip and an unthreaded shaft portion (28) arranged between the thread (26) and the screw head (20), the method comprising the following steps: screwing the screw (18) into the series of solid layers (12, 14, 16), at least one of the layers (14) in the series of layers (12, 14, 16) that is furthest from the screw head (20) being deformed in a screw-in direction, so that a thickness D.sub.p of the series of solid layers (12, 14, 16) is increased in a region directly around the screw (18) due to the deformation, continuing to screw in the screw (18) until the screw head (20) contacts and is supported on a flat surface of a first of the series of solid layers, a maximum thickness D.sub.p, max of the series of solid layers being reached at this moment and a length L.sub.F of the unthreaded shaft portion (28) is up to 10% less than or up to 30% greater than the maximum thickness D.sub.p, max of the series of solid layers.

2. The method according to claim 1, wherein the length L.sub.F of the unthreaded shaft portion (28) is up to 5% less than or up to 20% greater than the maximum thickness D.sub.p, max of the series of solid layers.

3. The method according to claim 1, wherein the length L.sub.F of the unthreaded shaft portion (28) is up to 3% less than or up to 10% greater than the maximum thickness D.sub.p, max of the series of solid layers.

4. The method according to claim 1, wherein the length L.sub.F of the unthreaded shaft portion (28) is equal to the maximum thickness D.sub.p, max of the series of solid layers, so that the screw stops being screwed in when the screw head (20) strikes the series of solid layers.

5. The method according to claim 1, wherein the length L.sub.F of the unthreaded shaft portion (28) is less than the maximum thickness D.sub.p, max of the series of solid layers, and by continuing to turn the screw, the thickness of the series of solid layers is reduced to a final thickness D.sub.p, end of the series of solid layers, the length L.sub.F of the unthreaded shaft portion (28) being equal to the final thickness D.sub.p, end of the series of solid layers.

6. The method according to claim 1, wherein at least part of the unthreaded shaft portion (28) has a diameter which is greater than a core diameter of the thread (26) and less than an outer diameter of the thread.

7. The method according to claim 1, wherein at least part of the unthreaded shaft portion (28) has a diameter which is less than or equal to a core diameter of the thread (26).

8. The method according to claim 1, wherein the unthreaded shaft portion (28) has, adjacent to the screw head, a shoulder (32) having a shaft diameter that is greater than a core diameter of the thread.

9. The method according to claim 1, wherein the thread (26) comprises, adjacent to the unthreaded shaft portion (28), a plurality of support points for the series of layers (12, 14, 16) which are an equal distance from the screw head (20), the support points delimiting the unthreaded shaft portion (28).

10. The method according to claim 9, wherein the plurality of support points are formed by the thread (26) extending into a planar, radially extending plane adjacent to the unthreaded shaft portion (28).

11. The method according to claim 9, wherein the plurality of support points are formed via a double thread or multiple threads.

12. The method according to claim 1, wherein the unthreaded shaft portion directly adjoins the tip.

13. The method according to claim 1, further comprising using a screw having a thread diameter of greater than 5.8 mm.

14. The method according to claim 1, further comprising using a screw having a thread diameter of greater than 6.5 mm.

15. The method according to claim 1, wherein the layer (14) that is furthest from the screw head (20) has a maximum thickness of 1 mm.

16. A fastening assembly (10), produced in accordance with a method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be explained by way of example on the basis of particularly preferred embodiments with reference to the accompanying drawings, in which:

(2) FIG. 1 shows a first embodiment of a fastening assembly according to the invention;

(3) FIG. 2 shows a second embodiment of a fastening assembly according to the invention;

(4) FIG. 3 shows a third embodiment of a fastening assembly according to the invention; and

(5) FIG. 4 shows a fourth embodiment of a fastening assembly according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(6) In the following description of the figures, like reference numerals denote like or similar elements.

(7) FIG. 1 shows a first embodiment of a fastening assembly 10 according to the invention. The fastening assembly 10 comprises a thin metal sheet 14 and an additional metal sheet 12 arranged thereon, which in the present embodiment is thicker than the thin metal sheet 14. The metal sheets 12, 14 form a series of metal sheets or series of layers 12, 14. The fastening assembly 10 also comprises a screw 18 comprising a screw head 20 and a displacement tip 22. A thread 26 extends into the displacement tip 22. The displacement tip 22 and the head 20 of the screw 18 are interconnected by a shaft 24. In the present embodiment, the shaft 24 is entirely unthreaded, i.e. the displacement tip 22 that comprises the thread 26 and tapers away from the screw head 20 is starts directly on the shaft 24. In other words, the unthreaded shaft portion 28 has a length L.sub.F that corresponds to the total length of the shaft 24. The shaft 24 also comprises a shoulder 32 which has a greater diameter than the unthreaded shaft portion 28, or in this case the entire shaft 24. This shoulder 32 provides improved seating of the screw 20 in the hole in the outer metal sheet 12 of the series of layers 12, 14.

(8) Before the screw 18 is screwed into the series of layers 12, 14, in this embodiment and in all the other embodiments set out here the outer metal sheet 12 already has a hole. This is not necessary, but preferred. Before the screw 18 is screwed in, the thin metal sheet 14 is generally intact, and it is in planar contact with the outer metal sheet 12. The thin metal sheet 14 extends over the hole in the outer metal sheet 12 and generally does not have any deformations, or has deformations that are insignificant in these contexts. Before the screw 18 is screwed in, the series of layers 12, 14 has a constant thickness Dp, .sub.1 in the entire region surrounding the screw, with constant metal-sheet thicknesses being assumed. If the screw 18 is then guided through the hole in the outer metal sheet 12 and screwed into the thin metal sheet 14, then the displacement tip 22 of the screw 18 displaces material from the thin sheet 14 in the screw-in direction of the screw 18. This forms a funnel-like structure 30. In the finished state of the fastening assembly 10 that is shown, the series of layers 12, 14 has an increased thickness D.sub.p, 2 in the direct vicinity of the screw 18 as a result. In the present embodiment, this increased thickness D.sub.p, 2 corresponds to the length L.sub.F of the unthreaded shaft portion 28. In this finished state of the fastening assembly 10, the thread 26 of the screw 18 is no longer in engagement with the series of layers 12, 14, i.e. is in particular no longer in engagement with the thin metal sheet 14. However, the funnel-like structure 30 in the thin metal sheet 14 provides a stop, which prevents the screw 18 from pulling out or loosening.

(9) The finished state of the fastening assembly 10 that is shown can be achieved in various ways, depending on the lengths, thicknesses and materials involved. In the simplest case, the length L.sub.F of the unthreaded shaft portion 28 is precisely coordinated with the type and nature of the other components such that the finished state of the fastening assembly 10 that is shown is reached at the moment at which the screw head 20 is resting on the outer metal sheet 12, that is to say the thread 26 makes the funnel-like structure 30 in the thin metal sheet 14 precisely at this moment. It is however also possible and particularly preferred for the thread 26 to still be in slight engagement with the funnel-like structure 30 when the screw head 20 is resting on the outer metal sheet 12. The screw 18 turning further then causes the funnel-like structure 30 to be pulled back in the direction of the screw head. Only then does the funnel-like structure 30 come out of engagement with the thread 26. At this moment, the fastening assembly 10 is under tension due to the forces exerted by the screw head 18 and the thread 26 on the series of layers 12, 14, and therefore a particularly stable fastening assembly 10 is produced.

(10) FIG. 2 shows a second embodiment of a fastening assembly 10 according to the invention. The fastening assembly 10 bears an insulating layer 34, which is connected to a very thin metal sheet 14 having a thickness of one millimeter, for example. By contrast with the fastening assembly shown in FIG. 1, a screw 18 is incorporated into the fastening assembly 10 according to FIG. 2 which comprises a thread-bearing shaft portion in addition to the unthreaded shaft portion 28. Starting from said thread-bearing portion, the thread 26 extends into the displacement tip 22 of the screw 18.

(11) FIG. 3 shows a third embodiment of a fastening assembly 10 according to the invention. The fastening assembly 10 shown here largely corresponds to that shown in FIG. 1. However, the inner metal sheet 14 is not a planar metal sheet, but a profiled metal sheet. Another difference is that the outer metal sheet 12 does not rest directly on the metal sheet 14 bearing the insulating layer 34. Instead, an intermediate element 16 is provided, which may also be designed as a metal sheet. The intermediate element 16 may also be designed as a plate, which consists of metal or for example of an elastomer. In particular, the intermediate element 16 may be a sealing strip. This is compressible, so that the series of layers 12, 14, 16 as a whole can be compressed if the thread 26 is still in engagement with the inner metal sheet 14 when the screw head 20 is resting on the metal sheet 12. As a result, relatively long thread lengths that are still in engagement with the inner metal sheet 14 at the moment at which the screw head 20 is resting on the outer metal sheet 12 are tolerated without undesired delamination of the series of layers. A fastening assembly using the sealing strip is suitable in particular for outdoor uses, while a fastening assembly without a sealing strip, as shown for example in FIG. 1, is suitable in particular for indoor uses.

(12) FIG. 4 shows a fourth embodiment of a fastening assembly 10 according to the invention. The fastening assembly 10 according to FIG. 4 corresponds to that shown in FIG. 3. By contrast with FIG. 3, the inner metal sheet 14 is not profiled in this case, but is planar.

(13) As shown in FIG. 4, adjacent to the unthreaded shaft portion 28, a plurality of support points 36 for the series of layers 12, 14, 16 which are an equal distance from the screw head 20 are provided by area where the thread extends into a planar, radially extending plane so as to be adjacent to the unthreaded shaft portion 28. The support points 36 delimit the unthreaded shaft portion 28.

(14) The features of the invention disclosed in the above description, the drawings and the claims can be essential to the implementation of the invention both individually and in any combination.

LIST OF REFERENCE NUMERALS

(15) 10 fastening assembly 12 metal sheet 14 metal sheet 16 intermediate element 18 screw 20 screw head 22 tip 24 shaft 26 thread 28 unthreaded shaft portion 30 funnel-like structure 32 shoulder 34 insulating layer