Field of the Invention

[0001] The present invention relations to fixings, in particular fixings for receiving and retaining bolt or screws.

Background to the Invention

[0002] Bolt or screws are designed to be screwed into a receiving fixing, so that the bolt or screw is immovable axially with respect to the fixing. Therefore bolts or screws can be used to effectively clamp other parts to the fixing, by tightening one against the other. Typical bolt or screws are commonly screwed into materials such as wood, plastics, metals or concrete in a self-tapping fashion, where the thread on the bolt or screw cuts into the receiving material and a receiving thread is fashioned in the material itself as the bolt or screw is wound inwards. Alternatively a nut or similar fixing may be used which has a thread corresponding to the thread on the bolt or screw. Screwing the bolt or screw into the nut achieves the same objective as above, but much greater force can be applied to the respective parts, and therefore a stronger fixing obtained.

[0003] The problem with all bolt or screws is the potential for cross threading when the bolt or screw is engaged with the fixing or the material to be self- tapped. This occurs when the threads on the bolt or screw do not match the threads on the fixing. When self-tapping is the mode of attachment, cross threading is where the material being screwed into disintegrates and the fashioned thread breaks up. In both these cases the functionality of the bolt or screw of being able to clamp against the fixing is diminished and can lead to fixing failure.

[0004] There is now described a fixing for receiving a bolt or screw which substantially mitigates or overcomes the above referenced and/or other disadvantages associated with the prior art.

Summary of the Invention

[0005] In an aspect of the invention there is provided a fixing for receiving a bolt or screw, the fixing comprising, a tubular member having a proximal end into which a bolt or screw is received in use, a distal end opposite the proximal end, and a plurality of resiliently flexible elements protruding inwardly from the internal side of the tubular member and directed towards the distal end.

[0006] The fixing according to the invention is advantageous primarily because it allows a bolt or screw to be engaged with the fixing by simply pushing it inwardly through from the proximal end of the tubular member. This action deflects all of the flexible elements further towards the distal end of the tubular member, until the bolt or screw can go no more. If the user then attempts to pull the bolt or screw out, the flexible elements engage with the recesses in the thread of the bolt or screw and tighten on it, thereby holding the bolt or screw in place. The bolt or screw is thereby engaged with the fixing in a push fit engagement without requiring it to be turned, and is prevented from moving outward of the tubular member in a direction towards the proximal end by simply pulling on it.

[0007] A further benefit of the fixing of the invention is that the bolt or screw can be engaged with the fixing tightly and quickly, without the possibility of any cross threading.

[0008] Preferably the flexible elements form a receiving thread which is cooperable with the thread on a bolt or screw in use inserted into the proximal end of the tubular member. This has the benefit that once the bolt or screw is inserted into the tubular member by push-fit, the bolt or screw can be further tightened within the fixing, by rotating it about its central longitudinal axis in the conventional fashion. The further rotation, causes the flexible elements to be forced towards the proximal end, and to tighten further on the bolt or screw. A further advantage of this is that the bolt or screw can be extracted from the fixing by simply unscrewing it in the conventional fashion. In conventional nuts and bolts, where cross threading has occurred, then separating the two by unscrewing is often impossible. [0009] The number of flexible elements within the tubular member may not exactly match the number of threads there are on the bolt or screw. Therefore some of the flexible elements may be engaged with the ridges of the bolt or screw when the bolt or screw is engaged, or just may miss consecutive recesses. The benefits described above are achieved when 50% but preferably over 75% of the number of the flexible elements within the tubular member match the threads on the bolt or screw.

[0010] Preferably the flexible elements are orientated on the inside of the tubular member to correspond with the thread pitch on the bolt or screw inserted into the tubular member. For example, the flexible elements may extend threadwise on the inside of the tubular member. This has the benefit that there is greater chance that flexible elements will engage all of (ie match) the thread on the bolt or screw.

[0011] It will be appreciated that the thread spacing on different bolts or screws changes considerably, however one other benefit of the invention is that the resilient flexibility of the flexible elements allows for the flexible elements to settle into the recesses of the threads of many different bolt or screw thread sizes. The fixing of the invention can therefore adopt a one size fits all arrangement. It will be appreciated though that for different diameter bolts or screws, then corresponding diameter tubular members of the fixing will be required.

[0012] The flexible elements of the plurality of flexible elements may form rings which are disposed along the length of the inside of the tubular member. This makes it easy to manufacture the tubular member. Preferably though, the plurality of flexible elements are grouped into two or more banks of flexible elements running longitudinally down the internal sides of the tubular member, the banks being separated from one another by gaps. This makes it easier for the flexible elements to accommodate within more of the recesses of the bolt or screw when it is inserted within the tubular member and therefore greater retention forces of the fixing with respect to the bolt or screw can be obtained.

[0013] The flexible elements may be fins, splines or needles. Preferably the flexible elements extend around at least part of the circumference of the inside wall of the tubular member. This provides the greatest interaction with the thread on the bolt or screw.

[0014] The tubular member can have any external dimension. The tubular member may have the external shape of a nut, with planar sides suitable for being received by a spanner or the like. This has the benefit that fixing can be turned instead of the bolt or screw to instigate the further tightening described above, once the bolt or screw has been push fitted into the fixing. Thus a greater clamping force can be generated. It also makes the fixing of the invention suitable for all instances where a conventional nut would otherwise be used. Other examples of devices that could be used to drive the fixing formed in this way include wrenches, or sized fixings.

[0015] The tubular member may be surrounded by a retaining portion to retain the fixing in place. Retaining the fixing in place means to maintain the fixing static within the material in which it is placed in, on or against. Maintaining as static means that the fixing cannot rotate, or move laterally out of the material, or move sideways within the material. For example the fixing may be embedded within a piece of wood and the retaining portion provides means to retain the fixing within the wood.

[0016] The retaining portion may comprise a bolt or screw mounted externally of the tubular member. For example, the external parts of the tubular member may be formed into a screw thread, which enables the fixing to be screwed into a receiving material. Example receiving materials include but are not limited to wood or concrete. Alternatively the tubular member may have a screw thread attached to it which functions as a retaining portion.

[0017] The retaining portion may comprise one or more splines mounted externally to the tubular member and running longitudinally parallel with the central axis. The splines may be fashioned as wedges or the like. The splines enable the fixing to be hammered into a receiving material and prevent rotation or extraction (ie due to friction fit with the material in which the fixing is embedded). [0018] The retaining portion may comprise one or more clamping elements. Clamping elements include but are not limited to protrusions from the main body of the tubular member which can clamp onto or into the material in which the fixing is placed in, on or against. The clamping elements preferably prevent rotation of the fixing and keep the fixing static within the material. The clamping elements may comprise one or more deformable parts which can be bent in order to clamp the fixing onto the material. Examples of clamping elements includes rivets or the like. Clamping elements may also include embodiments where the tubular member is widened at the proximal end so that the whole fixing forms a sort of inverted "T" shape. At the circumference of the widened parts there are sharp protrusions which are directed towards the distal end but parallel with the central axis of the tubular member.

[0019] The fixing according to the invention may be made of any of metal, plastic or composite materials. The fixing may be formed using any moulding, etching, or printing technique.

Brief Description of the Drawings

[0020] The invention will now be described by way of example and/or illustration only with reference to the accompanying drawings in which:

[0021] Figure 1 shows a cross section of an embodiment of the fixing according to the invention, with a bolt engaged with it.

[0022] Figure 2 shows an enlarged region of an embodiment of the fixing according to the invention, indicating the region of deflection of the flexible element.

[0023] Figure 3 shows a cross section of an embodiment of the fixing according to the invention, with a bolt engaged with it.

Detailed Description of the Illustrated Embodiment

[0024] In figure 1 there is shown an embodiment of the fixing generally labelled 1 . The fixing 1 has a tubular member 2 and a retaining portion 3 and a central bore 10 running through both. The tubular member has a proximal end 2a and an opposite distal end 2b. Both the tubular member 2 and the retaining portion 3 have a circular cross section. The fixing 1 is shown in Figure 1 with a conventional M8 steel bolt 4 engaged through the bore 10. The bolt 4 thread length is approximately 30mm long (thread pitch is 1 .25mm, thread depth is 0.55 mm, external diameter is 7.8mm) and has one end fashioned into a hexagonal nut (not shown) and the opposite end fashioned into a screw thread. The screw thread has recesses 5 and peaks 6 which are wound around the shaft of the bolt 4, as is convention. The fixing 1 is made of Nylon or plastic, but could also be made of steel. The bore 10 of the fixing is 2.5mm wider in diameter than the diameter of the bolt 4.

[0025] The tubular member 2 has a circular internal wall 7 and an external wall 8. Around the internal wall of the tubular member 2 there is disposed a plurality of flexible elements 9. The flexible elements 9 are integral with the wall 7 of tubular member and are formed with the tubular member 2 when it is manufactured. In the example shown the fixing 1 is manufactured from moulding. In other examples, the fixing may be manufactured by 3d printing, etching or sintering. In the example shown there are two banks of flexible elements 9 which run longitudinally down opposite sides of the internal wall 7 of the tubular member. Each bank of flexible elements comprises approximately 18 flexible elements within a length of approximately 22mm.

[0026] Each flexible element is moulded with the wall of the tubular member in a threadwise fashion, and with a thread spacing which is designed to cooperate with the thread on the bolt 4. Each flexible element 9 is made up of a thin strip of nylon or plastic (although metal could also be used) which occupies a portion of the circumference of the internal wall 7 of the tubular member 2. Between the banks of flexible members 7 there is a gap, one on each side of the internal wall of the tubular member. Each flexible element 9 comprises a fin with a sharp point at its tip.

[0027] Prior to inserting the bolt 4, the flexible elements 9 protrude inwardly from the internal wall 7 of the tubular member towards distal end 2b of the tubular member 2. The flexible elements 9 are resiliently deflectable and if deflected will spring back to their original position. Each flexible element has a length which is equal to 1 .55mm.

[0028] The retaining portion 3 of the fixing 2 has a wider diameter than that of the tubular member. At its extremity there is a sharp pointed edge 1 1 facing the distal end. The pointed edge 1 1 is broken into sections which extend around the circumference of the retaining portion 3, but the sections are separated by gaps. Also forming part of the retaining portion are two splines 12, which extend down the external wall 8 of the tubular member. The splines 12 are wedges which are formed integrally with the tubular member.

[0029] In use, the user drills a hole into a receiving material such as wood or concrete which is the same diameter as the diameter of the external wall 8. The user then hammers the fixing 1 into the hole, distal end 2b first. The splines 12 embed into the material, as does the retaining portion 3 and the sharp edges 1 1 . The bolt 4 is then introduced through the proximal end 2a of the tubular member. The user pushes on the bolt 4 all the way so that it is inserted all the way through to the distal end 2b or as far as possible. The length of the fixing is configured to be longer than then bolt 4, so as to accommodate all of the thread portion of the bolt 4. As the bolt 4 is pushed inwards the flexible elements 9 deflect towards the distal end and ride over the threads as they pass. When the bolt 4 can move no more, the flexible elements 9 settle into the majority of the thread recesses of the bolt 4, as shown in Figure 1 . In this position the flexible elements are deflected from their rest position and are tight onto the thread of the bolt 4. Outward movement of the bolt 4 forces the flexible elements 9 to tighten further onto the bolt 4 thereby preventing movement. Thus once the user has push fitted the bolt into place he cannot simply remove it by pulling it out again in a reverse motion. Rotation of the fixing within the material is prevented by the splines 12 and the sharp edges 1 1 . Using the fixing according to the invention the user can push fit a screw or bolt into place, and secure it fast within the fixing, without having to rotate it in the conventional fashion. Cross threading is thereby prevented. [0030] If required the user may then further tighten the bolt 4 into the fixing 1 . As the user screws the bolt in the conventional fashion, it forces the flexible elements towards the proximal end, and thereby tightens them further onto the shaft of the bolt. This may be required for aesthetic purposes, or to improve stability of the joint between the bolt and the fixing.

[0031] If the user then wishes to remove the bolt 4, all they have to do is unscrew it in the conventional fashion. As the flexible elements 9 are embedded within the recesses of the thread of the bolt, they form a cooperable thread and allow the bolt 4 to be extracted by rotation.

[0032] In figure 2 there is shown an expansion of a region of the side wall of the tubular member. The flexible element 9 is directed towards the distal end 2b. When the bolt is inserted the flexible elements 9 flex towards the distal end 2b within the arc A and engage with the threads on the bolt. When the bolt is attempted to be pulled out the flexible elements are pulled in the opposite direction, but the shaft of the bolt (not shown) prevents movement of the flexible member out of the arc A.

[0033] Figure 3 shows a further embodiment of the fixing according to the invention. The embodiment in figure 3 has all the features as described above, and works in substantially the same way, however instead of the retaining portion 3 being fashioned into a steel part which is wider than the tubular member with sharp edges 1 1 and splines 12, the tubular member extends completely to the proximal end of the fixing 1 . The external wall 8 of the tubular member 2 is fashioned into a screw thread 13. This screw thread enables the user to screw the fixing into the receiving material (ie wood or metal or concrete) rather than hammer it in as described above. This embodiment is easier to manufacture and has greater surface appeal.

[0034] The above examples describe the fixing of a conventional M8 bolt into the fixing 1 which is embedded into another material, such as wood or concrete.

[0035] In other examples of the invention the bolt 4 may be a double ended machine screw or the like. These types of screws have one end which is a con- ventional machine screw (similar to an M8 or the like) and an opposite end which is a wood screw thread. The wood screw part is screwed into a wooden foot or leg, for example for a sofa or the like. The conventional M8 machine screw part is then left exposed upstanding from the wooden foot, and is connected into the fixing 1 substantially as described above. As furniture often has fabric covering the various edges and parts, the feature of the fixing 1 , which provides that the bolt 4 can be further tightened into the fixing, means that joins in the fabric coverings, say between the leg and main sofa, are clean and neat and don't leave any gaps. This also provides extra security and strength to the engagement of the leg with the sofa. The inventors have also found that they could unscrew the leg easily when the sofa was required to be disassembled or transported. Thus the inventors have used the above invention in the field of furniture, although it will be appreciated that fixing according to the invention is not restricted to this field.

[0036] In a further example of the invention the external wall of the tubular portion is fashioned into a hexagonal nut to receive a spanner or wrench. The bolt and fixing of this embodiment can then be used clamp various items together as would a conventional bolt and nut. The fashioned tubular portion may perform the function of the retaining portion above, if for example the fixing is welded to or embedded within a secondary piece of material to which the bolt is required to be fixed.