ES2383732T3 - Retention tab for outgoing folding joint trays on wooden supports and wood derivatives - Google Patents

Abstract

In roof covering systems using zinc or zinc-alloy trays with standing-seam crimping, the use of tabs secured by two screws is well known. The invention particularly relates to a metal fastening tab for securing a standing-seam tray on a wood or wood-derivative carrier, which comprises a first surface (1) with a perforation (2) for receiving a screw for attachment onto the carrier, a second surface (3) generally perpendicular to said first surface and including a hook (4) for engaging with the ridge of the tray to be secured, the two surfaces defining an edge (5), characterised in that the first surface includes a single perforation (2) for receiving a single screw, and in that the centre (6) of said perforation (2) is not included in the mediator (7) of the edge (5) in order to reduce the force applied on the tab and on the tray by the torque induced when tightening said screw. Such a tab, with a single large-diameter screw, is easier and quicker to place than traditional tabs. The tab is specially designed to limit its own torsion and to avoid any buckling of the tray to be secured when tightening the single screw.

Description

Retention tab for outgoing folding joint trays on wooden supports and wood derivatives.

This invention relates to roof deck systems, in particular to systems employing zinc or zinc alloy trays for crimping protruding folding joints.

Such trays are normally fixed on the roof support with the help of fixed and movable metal tabs. The function of the fixed eyelashes is to tie the tray of folding projection joint to the support, which is usually made of wood or derived from it, blocking the movements of thermal expansion of zinc. The movable tabs are provided to suppress the zinc expansion movements induced by the variations of temperatures by tying the folding joint tray protruding to the sopote. The present invention relates to fixed tabs.

Existing fixed tabs are represented, for example, by the rules of the technique as described in France in DTU 40.41 (Unified Documents Techniques) entitled "Couverture par éléments métalliques en feuilles et longues feuilles en zinc". These fixing tabs comprise two holes, with or without flange, and are fixed with the help of ring tips or wooden screws with a diameter of 4 mm. Normally they are installed along the joint, every 33 cm.

However, we have found that the ringed tips as well as the small diameter screws up to 4 mm can jump due to the drying cycles of the wood and the repetitive efforts of the wind. In the same way, a large number of deck installers use automatic nailers for reasons of economy of installation time, which implies, however, a very great difficulty of application due to the volume of the machine. In addition, the tips are often hit hard and the tabs are deformed, or they are hit on the side of the flange holes. Which implies a risk of insufficient performance in terms of resistance to starting. An improperly installed flange creates a risk of bad crimping of the joint and, therefore, a defect in tightness and aesthetics.

Document GB 2 422 383 A publishes a tab according to the preamble of claim 1. Although the passage to a single large diameter screw seems a priori interesting, this generates, however, a specific problem to be solved. This tab is mounted, in effect, by aligning and hooking it along the tray to be fixed. But during the clamping of the single screw, a rotation torque is transmitted to the flange, all the more important the larger the diameter of the screw. Rather, such screws are provided, on their head, with pins initially provided for milling and thus better penetrate the wood. These generate additional frictions that still increase the torque transmitted to the flange during fixing. This pair will swing the flange until one of its ends rests on the tray to be fixed with sufficient blocking force. It has been found that this blocking force can deform the flange as well as the tray, things to be avoided.

The object of the present invention is a fixing flange that uses a single screw, therefore, easier and faster to install than the classic eyelashes. This tab is specifically designed to prevent it from deforming as well as deforming the tray to be fixed during the fixation of the single screw. Therefore, it provides greater installation safety and better mechanical performances.

Figure 1 illustrates the invention by means of a three-dimensional isometric view. Figure 2 represents a tab viewed from above.

The invention relates, in particular, to a metal fixing flange made in one piece to immobilize a tray of projecting folding joints on a wooden or derivative support, which comprises a first surface (1) provided with a perforation (2) intended to receive a fixing screw in the support, a second surface (3) generally perpendicular to said first surface comprising a hook (4) intended to cooperate with the edge of the tray to be immobilized, these two surfaces defining an intersection line (5) of length L, characterized in that this hook (4) and this first surface (1) extend from the second surface (3) in opposite directions and said first surface comprises a single bore (2) intended to receive a single screw , and because the center (6) of said perforation (2) is offset relative to the perpendicularly (7) of the intersection line (5), in the direction that reduces the stress exerted on the flange and on the tray by the torque induced during the fixing of said screw.

This flange is more particularly characterized in that the center (6) of the perforation (2) is offset at a distance D greater than 10% and preferably greater than 25%, from L in relation to the average perpendicular (7) of the intersection line (5), in order to reduce the stress on the flange and on the tray by the torque induced during the fixing of said screw.

The offset distance can be adjusted according to the intensity of the stresses resulting from the fixing torque. This intensity varies essentially according to the size of the screw heads used.

It is conceived that in order to reduce the stress on the flange and on the tray by the torque induced during the fixing of said screw, it is necessary to offset the center (6) of the perforation (2) by extending the end (9) of the destined flange The torque transmitted during screw fixation has to be passed on the tray, and not in the opposite direction. It is clear that Figures 1 and 2 correspond to a piece provided for a fixing screw with a right hand thread, that is, the usual case in which the fixing direction is the clockwise direction. With regard to the representation of Figure 2, it is therefore necessary to offset the drilling to the right.

It is useful to provide reinforcements (10) along the intersection line (5). These contribute in the same way to reduce the deformations of the flange during fixing, blocking the angle formed by the surfaces (1) and (3).

The perforation (2) intended to accept the fixing screw will preferably be provided with a flange (11), whose opening angle is usefully greater than 100 °.

This makes it possible to reduce the contact surface with the screw head and, therefore, reduce friction and thus also the torque transmitted to the flange during fixing. There are solutions to reduce friction due to lubrication or the use of interface materials, but they have the disadvantage of complicating the operator's work and increasing the cost of the solution.

Preferably, an AISI 304 stainless steel sheet will be used to make the piece by drawing. A thickness of 0.4 mm is suitable.

The new flange is fixed with the help of a single screw of 5 mm or 6 mm in diameter. Such a screw does not jump, however, under the effects of vibrations induced by wind and dimensional variations of the supports. Its superior resistance to start-up allows the eyelashes to be installed at a maximum of 75 cm instead of usually 33 cm maximum. Therefore, the new tab increases installation comfort significantly, allowing both easy installation and significant installation time gain by reducing the number of tabs and the number of fixings. On the other hand, these tabs are particularly compact, without the use of superfluous metal.

Claims (5)

1.- Metal fixing tab made in one piece to immobilize a tray of protruding folding joints on a wooden or derivative support, comprising a first surface (1) provided with a perforation (2) intended to receive a fixing screw in the support, a second surface (3) generally perpendicular to said first surface comprising a hook (4) intended to cooperate with the edge of the tray to be immobilized, these two surfaces defining an intersection line (5) of length L , characterized in that this hook (4) and this first surface (1) extend from the second surface (3) in opposite directions and said first surface comprises a single bore (2) intended to receive a single screw, and because the center (6) of said perforation (2) is offset in relation to the perpendicularly (7) of the intersection line 10 (5), in the direction that reduces the stress exerted on the flange and on the tray by the torque induced during the fixing of said screw. 2. Tab according to claim 1, characterized in that the center (6) of the perforation (2) is offset at a distance D greater than 10% of L in relation to the average perpendicular (7) of the line of intersection (5) to reduce the stress on the flange and on the tray by the torque induced during 15 fixing said screw. 3. Tab according to claims 1 or 2, characterized in that reinforcements (10) produced by stamping are provided along the intersection line (5). 4. Tab according to any one of claims 1 to 3, characterized in that the perforation (2) for receiving the screw for fixing to the support is provided with a flange (11). 5. A tab according to claim 4, characterized in that said flange (11) has an opening angle greater than 100 °. 6. Tab according to any one of claims 1 to 5, produced by drawing an AISI 304 stainless steel sheet.