A NUT

Abstract: A nut intended for being retained in a blind hole is provided with a number of lips (11) extending from the cylindrical part (1) of the nut and forming cutting edges (2) which extend most at the upper corner. When these edges (2) are turned in the direction of rotation (10) of the nut when a bolt (5) is being tightened, they will cut further into the wall of the hole. The result is a downturned force which will contribute to securing the nut in the object, and the bolt (5) will not be capable of loosening because the material (6) will be wedged in between the bolt (5) and the lip (11). If the nut is to be withdrawn from the hole, this is most easily done by turning the nut in the opposite direction at the same time while being drawn out. This will cause no appreciable damage to the material in the rim area of the hole.

Description: A NUT The invention relates to a nut, especially for fitting in a hole in an object of eg. wood, chip board, plas¬ tic or similar semi-hard material or for embedding in plastic, bakelite or similar moulding material which nut is made of rolled up sheet metal and pro- vided with punchings for forming lips bending outwards from the nut, said lips engaging the material when tightening a bolt screwed into the nut. Nuts of this kind are especially used for assemblies where the nut is to remain hidden in a bore in an object so that the assembly between a bolt and the nut can be separated according to requirements. The protruding lips extend at the lower section of the nut and protrude forwardly in the screwing in end of the nut for the bolt. When tightening the bolt, the nut is turned in the hole so that the bent out lips cut somewhat into the wall of material and thus anchors the nut. The bolt can then be screwed out without the nut leaving its position in the hole because of the en¬ gagement of the lips in the wall and the resulting friction engagement. During the tightening, lips of this kind are moved in the screwing in direction of the bolt. Especially during the initial tightening the nut will often be somewhat turned particularly in cases where the fit between nut and hole is loose whereby the lips are easily twisted so that they cannot cut into the material when the longitudinal movement of the nut starts. This will of course result in lesser fasten- ing abilities and, moreover, the lips will especially in hard materials easily break off so that the expect¬ ed anchoring is not obtained. Finally, a screwed in nut cannot be removed from the object without having to be drawn out with the lips in the material thus damaging the rim area. It is the object of the invention to remedy these drawbacks by the known nuts and this is achieved by a nut where each lip forms a cutting edge pointing in the direction of tightening of the nut. By tighten¬ ing a nut with such lips it will be anchored in the material by the cutting in of the lips into the wall of the hole at the same time as the bolt tightens. This cutting edge is pointing in the direction of rotation of the bolt and can therefore not so easily break off just as particularly in hard materials it will more easily be capable of going into frictional engagement therewith because of the abilites of the cutting edge to cut into the wall. This nut may also be drawn out of the hole f.inst. by means of an unscrewing stud with a counter nut that may turn the nut and thus the cutting edges clear of the engagement so that the nut may be easily drawn out without damaging the material. By designing the lips as disclosed in claims 2 and 3, there is obtained a cutting edge which by being cut into the material provides an anchoring as well as a downwards movement due to the shape of the cutting edge. This ec?ge forms a blade extending most at the top from where it extends inwardly towards the inner and bottom parts of the nut. The downturned force exerted by the pressure of the material on the blade which contributes to the tightening is thereby pro¬ duced. This will moreover ensure that the bolt in the nut is not undesirably screwed out because the pressed in material will be squeezed against the bolt which is thereby retained. Finally, it is advantageous as disclosed in claim 4 to form a rim part at the top of the nut so that the nut is fixed in the material by the tightening. The invention will be further described in the follow¬ ing with reference to the drawing wherein Fig. 1 is a perspective view of the nut, and Fig. 2 is a cross-section of the nut with a bolt screwed in. The drawing shows a preferred embodiment of the nut comprising a bush 1 made by bending a piece of sheet metal being formed as a hollow cylindrical bush. At the top of the bush there is formed a flange 3 which is substantially at right angles to the longitudinal axis of the bush. The inside of the bush is provided with a screw thread 4 extending in the entire length thereof. In the side of the bush there are punched three cuts 7, 8, 9 for each lip 11 said cuts being a longitudinal cut 7 determining the height of the lip and two transverse cuts whereof the upper cut 8 is somewhat longer than the lower cut 9. This produces a lip 11 having a cutting edge 2 being shaped as a blade with the pointed end at the upper corner. This shape will pro¬ vide the preferred cutting edge that will partly cut into the wall of the hole and partly produce a down¬ wards movement of the bush by compression of material across the blade which will force the blade and consequently the nut downwards. As shown in Fig. 2, the nut has been screwed into a blind hole in an object. After the insertion in the hole a bolt 5 has been introduced into the nut and screwed into same. By the screwing in in the direction of rotation 10, see Fig. 1, the cutting edges 2 have been cut into the material, and this material 6 has been carried towards the bolt 5. This accumulation of material will retain the nut in its screwed in position and thereby prevent an undesired loosening of the bolt and the nut. If the nut is to be removed from the hole, this may by done by turning same in a direction opposite the direction of screwing in 10 whereby the cutting edges will be withdrawn from the material, and the nut can be easily turned out of the hole. This removal will not damage the wall of the object in the same way as the known nuts. At the top of the nut there is designed a rim part 3 forming a collar on the nut. This collar will retain the nut against the surface of the object and will by use in chip boards, for example, ensure that the object is not damaged by even a strong tightening. Moreover, the rim part 3 will create a counter-pres¬ sure against the downwards stress and so the upwards reaction of material which particularly in connection with chip boards is necessary for avoiding damage of the rim area. When screwing in the bolt there is thus provided a turning of the nut into a point where the cutting edges have attained the required engagement in the wall of the hole for withstanding the turning moment of the bolt when said bolt has the desired torque moment. The nut according to the invention will also be suit¬ able for embedding in plastic, bakelite or similar moulding material. Contrary to the known nuts the cutting edges 2 will cause no formation of slots in the surrounding material so that there is obtained a considerably stronger retaining force than previous¬ ly seen. A contributory factor is the good distribution of stresses from the nut to the surrounding material. The transfer of force will substantially take place in directions downwards and outwards from the area around the cutting edges into the material where its strongest retaining force is present. The tendency to damages of the upper parts of material is thereby reduced.

Claims: PATENT CLAIMS 1. Nut, especially for fitting into a hole in an object of eg. wood, chip board, plastic or similar semi-hard material or for embedding in plastic, bakelite or similar moulding material, which nut is made of rolled up sheet metal and provided with punchings for forming lips bending outwards from the nut, said lips engaging the material when tightening a bolt screwed into the nut, c h a r a c t e r ¬ i s e i n that each lip (11) forms a cutting edge (2) extending in the direction of tightening (10) of the nut. 2. Nut according to claim 1, c h a r a c t e r ¬ i s e d i n that the lip (11) is cut out ofthebush (1) formed of sheet metal by partly a longitudinal cut (7) and partly two transverse cuts (8,9) extend¬ ing from the ends of the longitudinal cut (7) and somewhat to the rear in the direction of tightening (10) of the nut. 3. Nut according claims 1 and 2, ' c h a r-a c t e r - i s e d i n that the transverse cut (8) facing the screwing in end of the nut for the bolt (5) is longer than the underlying transverse cut (9). 4. Nut according to any one of the preceeding claims, c h a r a c t e r i s e d i n that at the screwing in end for the bolt (5) the nut is provided with a protruding rim part (3). . \\A-

Applicants: HOLM J H HOLDING, AKTIESELSKABET J.H. HOLM HOLDING
Application year: 1984
Main classification: F16B13
IPC codes: F16B37