FIXING DEVICE

Abstract: The invention provides a fixing device for porous building material of the lightweight concrete type and the like, for the attachment of different objects. The device is in two parts, namely a blade-shaped member with diverging side edges (2) in the direction in which it is intended to be driven into a substructure for taking up the load intended to be placed on the device, and a locking member for locking the support member in its driven-in position. The locking member consists of a metal strip bent into a U-shape, with a web (6) joining two legs (5) with a spacing corresponding to the least width of the support member. The locking member is intended to be driven into the substructure after the support member, such that its legs (5) glide along the diverging edges (2) of the support member.

Description: TITLE FIXING VIC TECHNICAL FIELD The invention relates to a fixing device comprising two members for driving into porous building material such as aerated or lightweight concrete for the purpose of fastening different objects. BACKGROUND The building material usually called lightweight concrete has come into use to an ever greater extent in recent years due to its good insulation properties, and is used in buildings for walls, roofs, ceilings and floors. This structural material has, however, a drawback in that there is difficulty in fastening anything into it solidly with sufficient strength, and accordingly there are problems in attaching roofing felt, false ceilings, ventilation ducts, plumbing and electrical fittings etc. to walls and floors constructed in the material. An ordinary nail or screw driven into lightweight concrete can generally by pulled out with the fingers, and does not sit very much more solidly if the nail or screw has been driven into a wooden or plastic plug inserted in a hole drilled beforehand in the material. A number of other configurations of fixing devices have therefore been proposed which give a more solid anchorage in these porous building materials. Such fixing devices are generally of the expander type and are usually distinguished in that they comprise q tubular r bifurcated for practically the whole of its length which, by the insertion of a screw, the action of a screw in coaction with a plug inserted between the two parts of the plug or by the action of a tool has its legs forced apart or "expanded" in the material into which the device has been placed. Such fixing devices have been rather satisfactory, but the lately increased demands for saving energy have required the manufacturers of lightweight concrete to make their pioJucLs even moi-e HO1OUS, and thereby lighter, to increase heat insulation ability. The strength values of the material are of course decreased t the same time, so that at the bulk density of 300-400 kg/m3 for lightweight concrete none of the fixing devices so far proposed gives satisfactory anchorage. The invention has therefore been directed towards the task of providing a new type of fixing device, which gives a better anchorage in lightweight concrete products so far on the market, and satisfactory anchorage with the new lightweight concrete having very low bulk densities which is under development. DISCLOSURE OF INVENTION In accordance with the invention the solution to this problem is that the configuration of the fixing device is adapted to include a large contact surface towards the lightweight concrete for taking up the load, at the same time as this surface is formed such that the load is substantially translated into a compressive force on the lightweight concrete and distributed over said contact surface. These conditions are satisfied by a fixing device in accordance with the invention as defined in the following claims and which mainly comprises two parts, the first of which is a planar blade-shaped member intended to be driven into the substructure like a nail and which is intended to support the load, said member having side edges diverging in the driving direction so that its profile has the appearance of a dovetail, the second of said parts being a U-shaped locking member with planar legs, and intended to be driven into the substructure, to lock the blade-shaped member in place after the latter has been driven in, such that the legs of the U-shaped member glide along the diverging side edges of the support member as the U-shaped member is driven home. Both said members are suitably stamped from steel strip, the support-member suitably being made of uniform width for a small distance from the end corresponding to the head of a nail, before the width successively increases towards the tip or "sharp" edge, i.e. before the side edges begin to diverge. The locking member is bent into a U-shape with its legs spaced to accommodate the least width of the support member. These legs are suitably provided with a centrally placed groove for stiffening the structure and also for guidance against the diverging edges of the support member during driving. It will be easily understood that if the support member of a fixing device in accordance with the invention is subjected to a load in the withdrawing direction, this load is translated into a pressure, directed away from the surfaces of the legs of the locking member, towards the surrounding substructure, and substantially uniformly distributed over the collected contact surface roof the locking member. legs against the material into which the fixing device has been driven. The fixing device may be adapted to different loads by suitable selection of driving depth, degree of divergence for the contour of the support member and width of leg in the locking member. It is also clear that if required, the fixing device can be removed after being driven in, namely by first withdrawing the locking member, which then runs in the grooves formed during driving it into place, subsequent to which the support member may be withdrawn. The head end of the support member - ,accordance with the invention is used for the conventional suspension or attachment of an object which is to be fixed to the substructure, e.g. a wall or ceiling made from the porous building material. In one embodiment the head end is bifurcated for a short distance, and the flaps thus formed are folded over to form a head for retaining a washer, e.g. if it is a question of attaching roofing felt to a lightweight concrete roof. In a second embodiment of the inventive fixing device, the support member is provided with a hole in the uniformly wide portion thereof, projecting from the substructure, for accommodating attachment means for a duct or other item to be instal in the building. In a third embodiment, the projecting portion of the support member is provided with one or more recesses in its parallel side edges for suitably adapted hooks or the like for attaching objects to the fixing device. DESCRIPTION OF DRAWINGS A pair of suitable embodiments of the invention are illustrated on the accompanying drawing, were Fig. 1 is a perspective view of a flat blade-shaped support member, Fig. 2 is a perspective view of a locking member, Fig. 3 illustrates the locking member driven into a lightweight concrete wall with the locking member then slipped over its projecting portion, both Fig. 4 illustrates/members driven into a light- weight concrete wall, Figs. 5 and 6 illustrate in plan a side view, respectively, a second embodiment of the locking member, Fig. 7 is a plan view of a washer intended for attaching roofing felt to a lightweight concrete roof, using the support member of Figs. 5 and 6, and Fig. 8 finally illustrates the use of said member together with the washer of Fig. 7 in attaching roofing felt to a lightweight concrete substructure. EMBODIMENTS As will be seen from the drawings, the inventive support member has a configuration consisting of s port ion with parallel side edges 1 and a portion with side edges 2 diverging in the direction in which the member is to be driven. The first-mentioned portion with parallel side edges is implemented with attachment means for an object which is to be kept in place with the aid of the fixing device, said attachment means being a hole 3 in Figs. 1 - 4 and a flattened head 4 in the embodiment according to Figs. 5 and 6. The locking member is implemented as a U-shaped, bent metal strip to form both legs 5 and their uniting web 6. In use together with the locking member illustrated in Figs. 1 - 4, a slot 7 is formed in the web 6, through which the parallel portion of the support member can be passed, so that the locking member may be driven home. This slot 7 is naturally not required for coaction with the support member according to Figs. 5 and 6. In all the embodiments, the legs 5 are suitably provided with centrally placed grooves or creases 8 for stiffening purposes, and also for guidance against the diverging edges of the support member during driving the locking member into place. The support member 1,2, as well as the legs 5 of the locking member have considerably less thickness than width. For most purposes, a thickness of about 2 mm has been found satisfactory when the other dimensions of the support member are a length of about 100-150 mm, least width about 10 mm and greatest width about 25-30 mm. If necessary, the locking member can also be stiffened by a longitudinal pressed groove. For fixing devices intended for attaching roofing felt and the like, a suitable washer 10, may be used, this washer being provided with guiding slots 11 for the legs 5 and a through passage or guiding groove 12 for the locking member. In Fig. 8 there is illustrated how roofing felt 14 is attached to the lightweight concrete substructure with the aid of the washer 10, which is re talijed by d zup iel er llavirig a head e sJ2ifw f small flaps bent in opposing directions and at 900 to said member, the locking member with its legs 5 being driven home so that its web comes against the head 4. In this case the locking member does not need to be provided with the slot 7 since its web is outside the head 4 the whole time. As will be seen in Figs. 3, 4 and 8 it is advantageous for the legs 5 to be made with a length relative the diverging edges 2 of the support member such that they penetrate somewhat deeper than the support member on being driven home. The tip 13 of the locking member has been shown as triangular, with an obtuse tip angle, but it may also be a single edge at an angle to the axis of said member.

Claims: CLAIMS 1. Fixing device for attaching an object to porous building material of the lightweight concrete type, characterized in that it comprises two parts, the first being a blade-shaped support member having diverging side edges (2) in the direction in which the member is to be driven into said material, said edges being intended for carrying the load on the device, and a locking member made from strip metal and with a U-shaped configuration, its legs (5) having a spacing corresponding to the width of the support member before its side edges begin to diverge, said legs (5) being adapted for gliding along the diverging edges of the support-member when the locking member is driven into said material. 2. Fixing device as claimed in claim 1 characterized in that the legs (5) are provided with central longitudinal grooves or creases (8). for guidance against the edges (1,2) of the support member when the locking member is driven home. 3. Fixing device as claimed in claim 1 or 2, characterized in that the portion of the support member having parallel side eges (1) is provided with means (3) for attaching objects intended to be fastened to the device, and that there is a slot (7) in the web (6) of the locking member, adapted to permit the passage of the portion of the support member having generally parallel edges. 4. Fixing device as claimed in claim 1 or 2, characterized in that the head end of the support member is enlarged to form a head (4), and in that the device further comprises, for the case where the fixing device is to be used for securing roofing felt or the like, a wesher (10) provided with guiding slots (11,12) for both said members. 5. Fixing device according to claim 4, characterized in that the head (4) is composed by that the blade shaped head end of the support member is bifurcated for a short distance to form flaps which are bent over in opposite directions at an angle of about 900 6. Fixing device as claimed in any of the preceding claims, characterized in that the support member is provided with a central longitudinal groove or crease, and that the slot (7) in the web (6) of the locking member-and the slot (12) in the washer (10), when such is used, are provided with a corresponding recess.

Inventors: RUBE, JAN
Applicants: RUBE, JAN
Application year: 1983
Main classification: F16B15
IPC codes: F16B15, E04B1