CURTAIN FACADE TOP

Description

[0001] The present invention relates to the field of curtain walls. It relates more particularly to the method of fixing a curtain wall to the structure of a building. This structure is generally a concrete or concrete block wall.

[0002] Curtain walls have a frame made of metal profiles, usually aluminum, connected to the building structure by connecting pieces. These pieces are usually metal and often shaped like a bracket. The expansion coefficients of concrete and aluminum are significantly different. This difference is reinforced by the difference in temperature exposure, as the concrete is protected by the curtain wall from direct exposure to the weather and sunlight. It is therefore important that the method of fixing the frame to the structure allows for the frame to expand relative to the structure.

[0003] To allow this relative expansion, the prior art provides for fixing the profile to the connecting piece using special screws.

[0004] Thus, document EP3199824A1 (SFS) describes a screw whose thread has a reduced diameter near the head of the screw, so as not to engage with the profile.

[0005] Document EP3564464A1 (SFS) describes a more complex system using a sleeve mounted on the screw.

[0006] Other prior art systems use screws comprising a thread provided with a sharp stop, on the head side, and a smooth part between the head and the sharp stop. The connecting piece and the profile are crossed by the smooth part and the sharp stop serves as a stop, so that the connecting piece and the profile are held between the head of the screw and the sharp stop. However, it is difficult to control the distance between the head of the screw and the sharp stop; thus, a functional clearance must be provided on the smooth part, so that the connecting piece and the profile are poorly held together.

[0007] The aim of the invention is to propose a simple fixing system which ensures good support of the profile on the connecting part, at the same time as allowing expansion of the profile.

[0008] According to the invention, a screw for fixing a profile of a metal framework to a part intended to connect this profile to a structure of a building, comprises a head and a shank, a first thread having a first diameter and furthermore a second thread having a second diameter smaller than the first diameter, the screw comprising a first threaded zone where the threads coexist and a second threaded zone, located between the first zone and the head, where only the second thread remains, so that the second thread extends beyond the first thread towards the head.

[0009] Such a screw is advantageously a self-drilling screw. The head of the screw may comprise a hexagonal socket. Preferably, the head comprises a collar between a socket and the shank.

[0010] According to a second object of the invention, a method for fixing a profile of a metal framework to a part intended to connect this profile to a structure of a building, this part comprising a wing pierced with an oblong hole (17), during which a screw is provided whose clear distance, measured between the first thread and the head of the screw, is greater than or equal to the sum of a thickness of said profile and a thickness of the wing at the location of the screw and whose diameter of the first thread is less than a width of this hole, then, the screw is introduced through the hole, then, the screw is screwed through the profile until the wing is pinched between the head of the screw and the profile, and, the second thread becomes blunt.

[0011] Several embodiments of the invention will be described below, by way of non-limiting examples, with reference to the appended drawings in which: [ Fig. 1 ] is a longitudinal view of a screw according to the invention for fixing a curtain wall profile to a part for connecting the profile to the structure of a building; and, [ Fig. 2 ] is a view of the screw of the figure 1 , engaged on a connecting piece and a profile.

[0012] THE figures 1 et 2 illustrate a screw 1 for fixing a profile 2 to a connecting piece 3. The screw extends longitudinally along an axis X1.

[0013] There figure 2 illustrates screw 1 in the position of use. Its longitudinal axis X1 is horizontal and the plane of the figure 2 is a horizontal plane P which includes the longitudinal axis X1 of the screw. The profile 2 and the connecting piece 3 are shown cut along the plane P. The profile 2 extends vertically, that is to say perpendicular to the plane P of the figure 2 , so that it is represented there in cross section. In the example illustrated, the horizontal, and cross section, of the profile 2 has a T shape. The connecting piece 3 has a horizontal section in the shape of a right angle of which only one wing 3A is partially represented in the figure 2 . A core 2A of the profile 2 is held against the wing 3A of the connecting piece 3, using the screw 1.

[0014] The screw 1 comprises a head 5 and a rod 6 which extends axially, along the longitudinal axis X1, from the head 5. The screw is a self-drilling screw; the distal end 7 of the rod has a drill shape.

[0015] The head 5 comprises a hexagonal socket 8 and, on the rod side, a collar 9. The screw is a double thread of the hi-low type, that is to say that the rod comprises a thread consisting of two interlaced threads 11, 12.

[0016] As particularly illustrated in the figure 1 , the rod 6 carries a first thread 11 with an external diameter D 11 and a second thread having a diameter D12 (called “low”, according to the English term) less than the diameter D11 (called “hi”, according to the English high) of the first thread (i.e., D12 <D11).

[0017] The second thread 12 extends beyond the first thread 11, towards the head 5. Thus, there is a first threaded zone 13 of the rod 7 where the two threads 11, 12 coexist and a second threaded zone 14 of the rod 7, between the first zone 14 and the head, which only carries the second thread 13.

[0018] In the illustrated example, the first thread 11 extends over a length L11 of the rod, from the drilling end 7 towards the head 5. The second thread 12 extends over a length L12 of the rod, from the drilling end 7 towards the head 5. The first zone has a length L13 substantially equal to the length L11 of the first thread 11, measured axially. The second zone 14 has a length L14 substantially equal to the length difference of the lengths L12-L11 of the two threads 11, 12, measured axially. The head 5 further comprises a connection profile 16 of the collar 9 to the rod 7, in a quarter circle. The first zone 13 is separated from the collar by a clear distance L9 greater than the length L14 of the second zone 14. The clear distance is measured without taking into account the “dying” part of the first thread 11, that is to say between the first thread, where it has its current diameter and the collar 9.

[0019] In the example illustrated, the core 2A and the flange 3A have thicknesses respectively noted E2 and E3. The clear distance L9 is greater than the sum of these two thicknesses, that is to say that L9 > E2+E3.

[0020] As illustrated in the figure 2 , the connecting piece is pre-drilled with a hole 17. It has a width L17, measured horizontally, in the plane P of the figure, greater than the diameter D11 of the first thread 11 and less than the diameter D9 of the collar 9 (D11 <D17<D9). Le trou est oblong, c'est-à-dire qu'il a une longueur, mesurée verticalement supérieure à la largeur L17.

[0021] Profile 2 is not pre-drilled; it is screw 1, when screwed in, which drills and taps the profile, respectively using end 7 and threads 11, 12.

[0022] We will now describe a method for fixing a profile of a metal frame to a structure of a building, using a screw according to the invention, with reference to the figure 2 .

[0023] The core 2A is positioned against the wing 3A. The screw is inserted into the hole 17 of the part 3 and screwed into the core 3A, so that the wing 3A is arranged between the core 2A and the head 5 of the screw 1.

[0024] It is noted that the clear distance L9 being greater than the sum E2+E3 of the thicknesses of the wing and the web, the first thread 11 escapes from the web, so that the web is no longer engaged except with the second thread 12. By continuing to screw the screw 1, the second thread 12 tends to drive the web 2A in the direction of the head, until the wing 3A comes into abutment against the collar 9 and is pinched between this collar and the web 2A, in the position, of the figure 2 . In this position, a longitudinal clearance J is created between the wing 2A and the first thread 11, such that J = L9 - E2 - E3.

[0025] When screwing continues, the second thread 12 being weak relative to the resistance exerted by the metal of the wing 2A, the screw continues to turn on itself at the same time as the second thread 12 “fails”, that is to say it becomes blunt, before the operator responsible for screwing realizes it.

[0026] This final arrangement constitutes an assembly position of the system consisting of profile 2, connecting piece 3 and screw 1.

[0027] In this position, the residual part of the second thread 12 exerts a residual longitudinal grip on the wing 2A, along the longitudinal axis X of the screw 1. This residual grip ensures a vertical sliding hold of the wing 3A between the collar 9 and the web 2A. This allows a vertical displacement of the profile, when it expands, relative to the wing 3A, guided by the screw 1 in the oblong hole 17. The part 3 being fixed to the structure of a building, the final arrangement allows an expansion of the metal frame relative to the more rigid structure of the building.

[0028] A proximal end of the first thread 11 constitutes a stop which keeps the screw engaged with the profile 2 and the connecting piece 3, in case the residual grip on the second thread 12, blunt, is not sufficient. Of course, several screws 1 are thus mounted on the same profile, so that suitable support is ensured.

[0029] The possibility of a longitudinal clearance J, permitted by the presence of the second thread 11, makes it possible to ensure that despite relatively low manufacturing tolerances, the screw 1 always has a clear distance L9 at least equal to the sum of the thicknesses E2, E3 of the core 2 and the wing 3.

[0030] In a preferred version of the system of the figure 2 , within manufacturing tolerances, we have the following theoretical dimensions: D11 = about 5.5 millimeters; D12 = about 4.8 millimeters; L11 = about 10 millimeters; L9 = about 6 millimeters; E2 = about 2.5 millimeters; and, E3 = about 2.5 millimeters; hence, J = about 1 millimeter.

[0031] Of course, the invention is not limited to the examples just described. On the contrary, the invention is defined by the claims which follow.

[0032] It will indeed appear to those skilled in the art that various modifications can be made to the embodiments described above, in light of the teaching which has just been disclosed to them.

[0033] Thus, a screw according to the invention may comprise more than two threads. For example, such a screw may comprise three or four threads; for example, two “hi” threads alternating with two “low” threads.

Claims

1. Screw (1) for fixing a section (2) of a metal framework to a part (3) intended to connect the said section to a structure of a building, characterized in that it comprises a head (5) and a shank (6), a first thread (11) having a diameter of diameter (D11) and further a second thread (12) having a second diameter (D12) smaller than said first diameter (D11), said screw comprising a first threaded area (13) where said threads (11, 12) coexist and a second threaded area (14), located between said first area (13) and the head (5), where only said second thread remains, so that said second thread extends beyond said first thread towards said head.

2. A screw according to claim 1, characterized in that it is a self-drilling screw.

3. Screw according to one of claims 1 and 2, characterized in that the head comprises a hexagonal socket (8).

4. Screw according to one of claims 1 to 3, characterized in that the head comprises a collar (9) between a socket and the shank.

5. Method for fixing a section (2) of a metal framework to a part (3) for connecting said section to a structure of a building, said part comprising a flange (3A) pierced with an oblong hole (17), characterized in that there is provided a screw (1) according to one of claims 1 to 4, a clear distance (L9) of which, measured between the first thread (11) and the head of the screw, is greater than or equal to the sum of a thickness (E2) of the said profile (2A) and a thickness (E3) of the flange (3) at the location of the screw (1), and the diameter of the first thread (D11) of which is less than a width (17) of the said hole, then that the said screw is inserted through the said hole, then that the said screw is inserted through the said flange (3A), then that the said flange (3A) is pierced with an oblong hole (17). through the said hole, then screwing the said screw through the said profile until the said screw is tightened the said wing is pinched between the head of the said screw and the said profile, and the second thread (12) is blunted.