FR2702808A1 - Improvements to devices for fastening objects onto sheets which are accessible from just one side - Google Patents

Abstract

This is a nut cage intended to be mounted in a rectangular hole 5 with parallel edges 6 hollowed from a metal sheet 7. To coincide with the screwing axis Z, the axis of the nut can be shifted transversely from an initial central position X, not only in a first direction d1 by sliding the cage along the edges 6, but also in a second direction d2 perpendicular to d1 by sliding the nut along the cage.

Description

Improvements to devices for fixing objects to sheets accessible from one side only.

 The invention relates to devices for fixing objects by screwing on supports, such as sheets, "blind", that is to say accessible on one side and perforated with suitable holes intended to be traversed in part by the devices in question, as is frequently required in the field of road, rail, aeronautical or other vehicle bodies, or even in the field of household arts.

 It is more particularly aimed, among the fasteners of the kind in question, those which include a one-piece plastic cage intended to contain a "threaded piece" - (nut, screw head, or nut primer for a screw digging its groove in the thickness of an appropriate body), said cage presenting itself in the general form of a cylindrical or prismatic box or "socket" of section small enough to be able to be introduced into the mounting holes of the sheet or similar support, one of the ends of this socket being extended transversely by a collar suitable for bearing on the accessible edges of said holes at the end of the introduction into said holes of said socket.

 Known fastening devices of this type require rigorous coincidence between the axis of the hole in the sheet and the screwing axis of the fixing device to be mounted in said hole, which axis is linked to the object to be fixed.

 This requirement may have drawbacks for certain applications.

 Thus, if the object to be fixed - such as a vehicle dashboard - has relatively large dimensions, difficult to control exactly, for example to the millimeter, and includes several fixing devices of the kind concerned above, relatively distant from each other and intended to cooperate with a common support, it is not uncommon that, after installation of the first fixing device on the support, the coincidence mentioned above is difficult or even impossible to achieve at the level of the last fastening devices, which leads to bias mounting with jamming and creation of undesirable permanent stresses: these stresses can result in the destruction of the cage, in particular when the screwings are carried out using machines automatic.

 Another example of application is that where the fixing device must be mounted on the assembly of a sheet and a covering of cardboard or plastic applied against this sheet, and where the two mounting holes hollowed out respectively in these two juxtaposed supports intended to receive the device are not rigorously arranged opposite one another.

 If in fact no freedom of adjustment is provided between the final position of the screwing axis and the axis of the main hole hollowed out in the sheet, the first of these two axes still takes a biased position when mounting the device so that its socket can pass through the two axially juxtaposed holes but slightly offset transversely, which creates jams during subsequent screwings.

 To overcome this drawback, a specific construction of the cage has already been proposed which makes it possible for this cage to be displaced, after its mounting on the sheet, along the two parallel edges of a slot constituting each mounting hole of the mounting device. fixing (see document FR-2 450 968).

 These devices are often entirely satisfactory.

 However, they make it possible to adjust the mutual transverse position between the screwing axis and the support in one direction, namely that of the parallel edges of the slot.

 The invention aims to make possible such an adjustment not only in this direction, but also in a second direction perpendicular thereto as well as to the screw axis, that is to say ultimately according to all directions perpendicular to this axis.

 To this end, the fixing devices of the kind in question according to the invention, intended to be mounted in "slots" with parallel edges hollowed out in a support, also include a cage suitable for sliding transversely along the edges of this slot after its mounting, but before screwing ensuring the desired fixing, and they are essentially characterized in that in addition the threaded part is itself mounted in the cage so that it can slide transversely along this cage, after mounting of the latter, but before the fastening screw, in a direction perpendicular to that of the edges of the slot.

In preferred embodiments, use is also made of one and / or the other of the following arrangements.
the bushing has, in a manner known per se, on the one hand, over the greater part of its axial length from its end furthest from the flange, a width in a given transverse direction dl slightly less than the width of the mounting slot and, on the other hand, over the portion of its external lateral surface disposed opposite the edge of the perforated plate at the end of an axial introduction of the cage into the slot with its width above placed perpendicular to the parallel edges of this slot, a profile allowing subsequent 90 "rotations of the cage around its axis in one direction only and the cage is arranged in such a way that the above axial insertion of the sleeve ends by axial stop of the heads of four spouts of the cage against the sheet and that, after subsequent rotation of a quarter turn of the cage in the screwing direction, its mounting can be completed by a final axial thrust exerted on it, thrust which, by a click effect, elastically overlaps the edges of the slot by the four nozzles,
the threaded part has two flat transverse wings of substantially rectangular shape, the parallel edges of which are capable of sliding against substantially planar walls constituting the socket and comprise notches constituting end-of-travel stops, capable of cooperating with the lateral edges of said walls,
the internal walls of the sleeve include ribs with rounded profile extending parallel to the general axis of this sleeve and capable of being overlapped by grooves of the threaded part with a view to its transverse centering before use, the corresponding locking of this part being removable by simple exercise on it low stresses to the transverse sliding.

 The invention includes, apart from these main provisions, certain other provisions which are preferably used at the same time and which will be more explicitly discussed below.

 In what follows, a preferred embodiment of the invention will be described with reference to the accompanying drawings in a manner which is of course not limiting.

 Figure 1 of these drawings shows in external view a fixing device established in accordance with the invention, device mounted on a portion of blind sheet hollowed out by a rectangular hole.

 FIGS. 2 and 3 show the same assembly, respectively in side view, cutaway portions, according to the arrows Il-Il of FIG. 1, and in cross section according to III-III, FIG. 2.

 FIG. 4 also shows the same assembly in side view, portions cut away, according to arrow IV of FIG. 1, after refocusing of the threaded part relative to the cage.

 FIGS. 5 and 6, finally, show the cage alone in respectively the two axial directions shown diagrammatically by the arrows V and VI in FIG. 4.

 In the selected embodiment, the fixing device comprises a cage 1 and a nut 2.

 The cage is formed by a single piece molded from a sufficiently strong plastic material such as a polyamide or an acetal resin, a piece comprising a cylindrical or prismatic "bushing" 3 of general axis Y bordered at one of its ends. axial by a projecting radial flange 4.

 The device considered is intended to cooperate with rectangular holes or slots 5 having two parallel edges 6 spaced from one another by a distance a, these holes being hollowed out in a sheet 7 or similar support.

 In the illustrated embodiment, the length of the slot 5 is limited so as to form a rectangular hole whose parallel edges 6 constitute the long sides and whose general axis is designated by the reference X.

 The cross section of the socket 3 must of course be small enough to be able to be introduced into the hole 5.

 The socket has for this purpose, in one of its transverse directions d1 (Figure 3) a dimension b slightly less than a.

 This socket is delimited laterally by two flat and parallel walls 8 extending perpendicular to the direction d1.

 These two walls are connected together, at the end of the socket furthest from the flange 4, by a pierced bottom 9 which has the general shape of an elongated ring comprising two flat sections connected together by two sections of semicircular end 91.

 The two flat walls 8 are relatively narrow, their width c (FIG. 3) being less than the dimension b and they are offset transversely with respect to each other, being symmetrical with each other with respect to the general axis Y of the cage.

 In addition, each of them has a beveled portion 81 on its outer face, in the vicinity of its longitudinal edge closest to the axis.

 This offset and this bevel make it possible, in a manner known per se, to rotate the cage 1 through the hole 1 through 90 ", after its axial introduction into this hole, this rotation being possible only in one direction, know that corresponding to the screwing from the outside of the sheet and its amplitude being limited to 90 ".

 The cage further comprises, near its rim 4, four small nozzles 10 which are open towards the outside in the transverse direction d2 perpendicular to dl and which are returned towards the rim 4 (see FIGS. 2, 4 and 6).

 As clearly visible in FIG. 4, the distance between the bodies 101 of the two nozzles 10 of each pair of nozzles in the direction d2 is slightly less than the width a of the hole 5 while the points 102 of these nozzles project towards the outside of the cage up to a mutual spacing greater than said width a.

 The bodies 101 of these spouts are sufficiently thin to be elastically flexible and their heads 103 have externally inclined faces 104 capable of cooperating by sliding with the edges 6 of the hole 5 so that the attachment of these spouts to these edges can be automatically obtained by a click effect.

 In addition, in the direction d1, the distance between the heads 103 of the spouts is greater than the width a (see FIG. 6).

 As for the nut 2, it essentially comprises a central ring 11 internally threaded with axis Z (Figures 2 and 3) and two transverse flat wings or lugs 12 of substantially rectangular shape elongated radially.

 These legs are corrugated by successions of grooves and ribs parallel to the length of the legs so that their resistance to bending is increased.

 The edges of said tabs 12 are notched by notches 13, the flat bottoms of which are capable of sliding along the flat walls 8, the sides 14 of these notches constituting end of travel stops capable of cooperating with the edges 15 of the walls 8.

 Given the transverse offset, which was indicated above, between the two walls 8, the locations of the two stops 14 corresponding to each notch 13 are themselves asymmetrical as clearly visible in FIG. 3, but the two notches 13 d '' a given nut are symmetrical to each other with respect to the axis Y of this nut and each end stop of the transverse sliding movement of the nut is ensured by simultaneous stop of two stops 14 belonging respectively to the two notches 13 against the two edges 15 of facing walls 8.

 To provisionally center the nut 2 in the cage 1 in the transverse direction of its sliding, and before its use, there is advantageously provided, slightly projecting from the inner face of each wall 8, a rib 16 with rounded profile suitable for cooperating with a complementary groove 17 hollowed out in the bottom of each notch 13.

 The implementation of the fixing device described above is as follows.

 The cage 1 is placed opposite the hole 5 hollowed out in the sheet metal 7, with its general axis Y coinciding with the general axis X of said hole and with its direction d1 parallel to the edges 6.

 The cage is pushed axially into the hole until the heads 103 of the nozzles 10 stop against the sheet.

 The cage is then rotated 90 "clockwise, that is to say in that of the screwing, while sliding the heads 103 against the sheet.

 A final axial thrust is then exerted on the cage, which elastically deforms the bodies of the spouts, then hooks these on the edges 6 of the hole by a click effect.

 The assembly of the cage is then completed and, if it is assumed that it was carried out in the middle of the length of the hole 5, the axes X and Y are merged as well as the axis Z of the nut, assumed to be centered transversely by cooperation of the ribs 16 with the grooves 17.

 The problem to be solved is the screwing into the nut 2 of a screw (not shown) whose axis is fixed and offset with respect to the triple axis defined above, and this as well in the direction d1 as in the direction d2, the axis of this screw being assumed to be located at the location designated by the letter Z in FIG. 1.

 The screw in question has for this purpose a pointed end which allows it to penetrate into the opening of the nut 2, which is advantageously delimited, towards the outside of the sheet, by a flared entry 18.

If we then continue the axial introduction of the screw into the nut along the Z axis imposed for this screw, we automatically observe two independent displacements which combine together to bring the triple axis defined above closer to l screwing axis, knowledge
on the one hand, a sliding of the cage 1 along the edges 6 of the hole 5 parallel to the direction a1,
- And, on the other hand, a sliding of the nut 2 relative to the cage 1 parallel to the direction d2.

 The screwing of the screw in the nut can then be carried out, which firmly applies the lugs 12 of the nut against the hidden face of the sheet 7 while ensuring a transverse immobilization of the screwed assembly relative to this sheet and in Therefore prohibiting all sliding in the two directions d1 and d2.

 In embodiments which have given all satisfaction, the transverse offsets between the initial mounting axis of the nut and the final screwing position of this axis were between + 2 mm and + 3 mm in each of the two directions d1 and d2.

 Following what and whatever the embodiment adopted, there is finally obtained a fastening device by screwing on blind sheet or similar support whose constitution, implementation and advantages (in particular that of allowing an adjustment of position by sliding in all directions perpendicular to the screw axis) result sufficiently from the above.

 As goes without saying, and as it already follows from the above, the invention is in no way limited to those of its modes of application and embodiments which have been more especially envisaged; on the contrary, it embraces all its variants.

Claims (4)

 1. Device for fixing an object by screwing on a blind sheet or the like perforated by a mounting slot (5) with parallel edges (6), comprising a monobloc plastic cage (1) intended to contain a "threaded part" ( 2) and being in the general form of a cylindrical sleeve (3) extended by a radial flange (4), said cage being arranged so as to be able to slide transversely along the edges of the slot after its mountain, but before the screw connection ensuring the desired fixing, characterized in that the threaded part (2) is itself mounted in the cage (1) so that it can slide transversely along this cage, after assembly of the latter, but before the fixing screw, in a direction perpendicular to that of the edges (6) of the slot (5).  2. Fastening device according to claim 1, wherein the sleeve has, on the one hand, over most of its axial length from its end furthest from the flange, a width in a given transverse direction dl slightly less than the width of the mounting slot (5) and, on the other hand, on the portion of its outer lateral surface disposed opposite the edge of the perforated sheet (7) at the end of an axial introduction of the cage in the slot with its width above placed perpendicular to the parallel edges of this slot, a profile allowing subsequent rotations of 90 "of the cage around its axis in one direction, characterized in that the cage is arranged so such that the above axial introduction of the sleeve (3) ends by axial abutment of the heads of four spouts (10) of the cage against the sheet and that, after subsequent rotation of a quarter of a turn of the cage in the meaning of vi ssage, its mounting can be completed by a final axial thrust exerted on it, thrust which, by a click effect, elastically overlaps the edges (6) of the slot (5) by the four nozzles.  3. Fastening device according to any one of the preceding claims, characterized in that the threaded part has two flat transverse wings (12) of substantially rectangular shape whose parallel edges are adapted to slide against substantially planar walls (8) constituting the sleeve (3) and comprise notches (14) constituting end-of-travel stops, suitable for cooperating with the lateral edges (15) of said walls.  4. Fastening device according to any one of the preceding claims, characterized in that the internal walls of the sleeve include ribs with rounded profile (16) extending parallel to the general axis of this sleeve and suitable for being overlapped. by grooves (17) of the threaded part (2) for its transverse centering before use, the corresponding locking of this part being eliminable by simple exercise on it low stresses to the transverse sliding.