Technical Field

The present invention relates to a fastener for securing an element of one cross-sectional shape in a hole of a different cross-sectional shape. The invention finds application in, for example, securing uprights in pieces of furniture, for example cupboards, shelves, tables, chairs etc.

Background Art

It is easier and cheaper to shape wood in rectangular cross-section than in circular cross- section, i.e. doweling. This is because cutting and planing operations are generally planar in nature and therefore it is relatively straightforward to make rectangular cross-sectioned wooden elements. On the other hand, circular cross-sectioned wood requires a much more complex shaping operation, making doweling much more expensive.

On the other hand, it is much easier and cheaper to form a round hole in an object, e.g. by a drilling operation, than to form a rectangular-sectioned hole, which requires multiple cutting operations.

It would be desirable to gain the cost advantage of the use of rectangular-sectioned elements and secure them in circular-sectioned holes.

Rakks/Rangine Corporation of 330 Reservoir Street, Needham, Massachusetts 02494, United States of America disclose a range of shelving that can be supported on poles. The poles can pass through a countertop and grommets may be provided to allow the poles to pass through the countertops. The grommets have a circular outline and include a square or rectangular hole passing through the grommets through which the poles can pass. The grommets are held within a round hole in the countertop by means of epoxy resin. The grommets do not secure the poles within the grommets but rather the poles are slidable within the grommets. EP 1878359 discloses a joint for joining a circular-sectioned post, which has a series of pre- dri Med holes spaced along its length, to an outer structure, such as a shelf, rack, table or box. The joint is formed by a tapered 2-part split collar that is fixed around the post and then the collar and the post are inserted into an opening provided in the edge of the structure. The opening has a taper corresponding to the taper of the collar and so when the insert is pushed into the opening, the structure is supported on the post by the taper in the collar and the corresponding taper in the opening. The inside of the 2-part collar includes pins that project into the pre-drilled holes in the post to secure the collar in a fixed position on the post. Such an arrangement requires a tapered opening in the structure, which is complex to form and requires the post to be pre-drilled with holes, which leads to an additional manufacturing step and limits the choice of the location of the joint only to the locations of the holes in the post.

A similar arrangement is provided in AU-2007 1954 in which metal shelves are supported on metal posts using a tapered split collar that is secured in a given location on the posts by means of pins provided within the collar that engage with pre-drilled holes in the post. The corners of the shelves are each provided with a tapered metal sleeve into which the tapered collar is inserted to support the shelf at a fixed height on the post. This arrangement is limited to fixing circular posts in circular openings. The disadvantages of this arrangement are similar to those discussed above in connection with EP 1878359. The arrangement disclosed in CA-2586419 is similar to that disclosed in AU-2007 1954 but uses wire shelves and instead of tapered sleeves at the corners of the shelf, it uses two wire loops, one having a wider diameter than the other, thereby effectively forming a tapering channel.

Finally, US 2010/0155352 discloses a similar arrangement to AU-2007 1954 except that the posts are of square cross-section and the corresponding tapered collars are also square.

In all the prior art documents mentioned above, the sides of the split collars are conical in shape and the opening into which the collars fit are also conical. This has the distinct disadvantage that it is much more difficult and expensive to form a conical opening than it is to form a cylindrical hole since a cylindrical hole can be formed easily by simple drilling operation. The present invention is based on the realisation that it is possible to provide a fastening that would be secured in a cylindrical hole, that is to say a opening with straight, and not tapering, sides.

Disclosure of the Invention

The present invention is defined by reference to the accompanying claims.

Broadly stated, the present invention provides a fastener for securing an element of a first cross-section (preferably of a rectangular or a square cross-section) in a hole of a different cross-section (generally of circular cross-section). The fastener has an internal opening having a shape corresponding to the cross-section of the element and an outside perimeter having a shape that corresponds to the shape of the hole.

The dimensions of the internal opening in the fastener are matched to the dimensions of the element so that the element is held tight by the fastener when inserted into the hole. The fastener includes at least two parts that fit around the element and in this way it is possible to achieve the tight fit of the fastener around the element while at the same time making the fastener easy to fit around the element. It also allows the fastener to be secured at any place along the length of the element. If the fastener were a one-part construction, it would be difficult to achieve such a tight fit between the fastening and the element while allowing a user to place the fastener at a desired location part of the way along an elongate element, which would be desirable, for example to reposition a shelf.

The outside diameter of the fastener should match the diameter of the hole so that the insertion of the fastener into the hole keeps the at least two parts of the fastener together and hold the element tightly within the fastener and therefore secures the element at a given position within the hole. Each of the parts of the fastener preferably has an outside surface that forms part of the periphery of the fastener and an inside surface that forms part of the opening in the fastener. It is less critical to match exactly the dimensions of the opening in the fastener to the cross- section of the element if the internal wall of the opening forms a non-sliding connection with the element. For example, the internal wall may be provided with projections that project into the element and hold the fastening and the element in a fixed position relative to each other. Such projections may take the form of teeth that bite into the surface of the element, which is particularly useful when the element is made of a compliant material such as wood. Instead of providing individual teeth, the internal wall of the opening can include at least one roughened area; such a roughened area can be considered as being made up of a large number of small projections. A further possibility is that the internal wall of the opening may include a resilient material, such as rubber, that is compressed when the fastener is secured around the element and inserted into the hole. A further possibility occurs if the element is itself made of a resilient material, for example wood, since the internal wall of the opening in the fastening may compress the resilient material of the element to provide such a non- sliding connection. Alternatively projections could be provided that fit into corresponding recesses pre-formed along the length of the element at the place where it is desired to fix the fastening. Of course, the projection could, in the latter case, be provided on the element and the corresponding recess could be provided on the fastening. , However, the use of such pre-formed recesses has the drawback that it requires the fastener to be secured at a predetermined location on the element and does not allow the fastener to be secured anywhere along the length of the element.

The fastener should fit snugly into the hole so as to maintain the relative positions between the fastener and the element. The use of resilient material in the connection between the element and the internal opening of the fastener is particularly advantageous since the resilience tends to urge the parts of the fastener against the walls of the hole, which assists in keeping with the fastener in the hole. Thus, for example, the provision of teeth on the internal wall of the opening of the fastener, in conjunction with a wooden element, allows the teeth to grip onto the element and prevent slippage of the element within the fastener while the resilience of the wood tends to force the parts of the fastener apart against the inside of the hole, thereby providing a tight fit of the fastener in the hole. Although the above discussion refers to making the inside surface of the fastener of a resilient material, such as rubber, it is possible to make the whole of the fastener from such a resilient material, although if that is the case, the rubber should be hard rubber to prevent undue movement between the elements and the hole. As mentioned above, the fastener is made in two or more parts. Adjacent parts of the fastener preferably form a joint together when secured around the element. Such a joint prevents the two parts of the fastener from becoming separated from each other, especially during the insertion of the fastener element into the hole. The joint between the adjacent parts of the fastener preferably prevents axial movement between the parts, when connected together. The term "axial movement" means movement of the two parts relative to each other in a direction parallel to the axis of the opening in the fastening. The parts may be connected together by a simple male/female joint that engage with each other when the parts are fastened around an element.

The fastener preferably includes an abutment limiting the amount by which the fastener can be inserted into the hole. This abutment could be in the form of a flange around the top or, more usually, around the bottom of the fastener. The abutment has a diameter greater than that of the rest of the fastener and so cannot fit into the hole and engages the surface around the hole as the fastener is inserted into the hole.

According to one embodiment, the fastener includes two parts that are identically shaped so that it is not necessary to choose between differently-shaped parts when assembling a fastener.

The element is preferably an elongated element, although it need not be and can be of any desired shape.

The present invention is ideal for resisting forces that tends to cause relative movement between the element and the part in which the hole is formed, such forces causing the element to be moved further into the hole or to move through the hole in the same direction as the element was inserted. In one embodiment, the element may form the leg of a piece of furniture, which can then support the piece of furniture and items within or on it. For example, the present invention can be used to secure poles in displays or shelving units and for securing the shelves themselves on the poles. They can also be used for securing legs in tables, chairs or stools, or in kitchen or other storage units. However, the present invention is not limited to the field of furniture and it has many applications in a variety of different fields for securing any element of one cross-section in a hole of a different cross- section.

Although the present invention has been described above in terms of a rectangular element and a round hole, the invention is not limited to such a configuration and, for example, hexagonal elements can be secured in the same manner; furthermore, the hole may be of a non-circular shape, such as oval or even square. It will be appreciated from the above discussion, and particularly the fact that the whole may be formed by a drilling operation, that the hole is of constant cross-section along its length, i.e. cylindrical in shape as opposed to tapering.

The present invention also extends to an article in which an element is secured using a fastener as generally described above. Furthermore, the present invention relates to a method of securing an element in a hole using a fastener, as generally described above.

Description of the Drawings

There will now be described, by way of example only, an embodiment of the present invention in which:

Figure 1 is a bottom view of a fastener in accordance with the present invention;

Figure 2 is an isometric view of one part of the fastener of Figure 1 taken from the top left;

Figure 3 is an isometric view of the rear of the part of Figure 2 taken from the top left; and

Figures 4 and 5 show the steps of securing an element in a hole using the fastener of Figures 1 to 3, which is ; the fastener is shown in ghost form so that the internal elements of the fastener are visible, as well as the external features. Detailed Description of a Preferred Embodiment

Referring initially to Figures 1 to 3, the fastener 10 includes two parts, 12, 14 (see Figure 1); Figure 1 shows both parts of the fastener but each part 12, 14 is identical and accordingly, only one part is shown in Figures 2 and 3. Each part 12, 14 is made of plastic material, for example nylon, and can be made by injection moulding. Each part 12, 14 includes an opening 16 and a semi-circular periphery 18, which is composed of a cylindrical wall 20 and a flange 22. Within the opening 16 there are provided five teeth, two large teeth and three small teeth 24 (only one large and two small teeth are visible in Figure 2), which can be seen to be pointed teeth. On the side walls of the openings 16, there are provided a pair of tabs 26 whose function is to hold the fastener part on an element while the two parts are assembled around the element, as further described in detail below.

The two parts 12,14 are intended to abut each other at end faces 11,15. One end face of each part 12, 14 includes a projection 28 while the other end face includes a recess 30 (see Figure 2). The projection 28 on each part can be inserted into the corresponding recess 30 in the other part when the two parts are brought together, thereby joining the two parts together and preventing relative movement between the two parts in the axial direction, i.e. in a direction parallel to the axis of the opening 16 and parallel to the direction of the axis of the element. Above each projection 28, there is provided a cut-out 32 and above each recess 30, there is provided an overhang 34. The overhang 34 of each part 12, 14 engages in the cut-out 32 of the other part when the two parts are engaged together.

Referring now to Figure 3, which shows the back view of the part 12, including a side wall 20 and a flange 22, as described above. A through-hole 36 may be provided in the side wall 20 through which a screw can be passed to engage an element within the opening 16. The hole 36 is, as shown, counter-sunk. However, in view of the teeth 24, it is generally not necessary to use a screw, in order to secure the fastener to an element located within the opening 16.

The side wall 20 includes a number of grooves 38 to provide flexibility to the side wall when it is being inserted into a hole (see below). It will be observed that the top of the side wall 20 is chamfered at 40 to assist in the insertion of the fastening into a hole. Turning now to Figures 4 and 5 which show the way in which the fastener is secured around a square section element 42 and then inserted into a hole 44 in an article shown

schematically with the reference number 46. The diameter of the hole 44 is approximately the same as the diameter of the fastener wall 20 when the two parts 12, 14 are engaged together. Therefore, the insertion of the fastener into the hole 44 keeps the two parts 12, 14 in engagement with each other and with the element 42. The element 42 may be made of wood or other material that can receive the teeth 24, although harder material can be used, especially if there is a projection on the inside surface of the opening 16 that can project into a recess in the element 42 (or vice versa); alternatively, a screw can be inserted through the counter-sunk opening 36 to engage the fastener on the element 42. In addition or instead of the use of teeth, a resilient (and preferably high friction) material(not shown), for example natural or artificial rubber, may be provided within the opening 34; this material is deformed by the pressing of the part 12, 14 around the element located in the opening, thereby holding the fastener in position on the element. Other alternative arrangements to prevent slippage between the elements and the fastener are described above.

In order to secure the fastener around the element 42, the overhang 34 on each part 12, 14 is engaged in the cut-out 32 of the other part, as shown by arrow A in Figure 4, i.e. the top of the fastener parts 12, 14 are engaged before the bottom of the fastener parts. The tabs 26 can loosely engage the outside surface of the element 42 to keep the fastener on the element while it is being engaged around the element. The bases of the two fastener parts 12, 14 are then brought together as shown by arrows B in Figure 5, which causes the projections 28 on each fastener part to engage in the corresponding recess 30 of the other part and also causes the teeth 24 to bite into the element 42. Once the fastener is engaged around the element 42, it is pushed into the hole 44 in the axial direction, as shown by arrow C of Figure 5. The fastener is inserted into the hole until the flange 22 engages the area around the hole when the fastener can be pushed no further into the hole. Because of the tight fit of the fastener in the hole, the tight fit of the element within the fastener and because of the engagement of the teeth 24 in the element 42, the latter is held rigidly within the hole against forces pushing down on the article 46, i.e. forces pushing vertically downwards on the article 46. This means that the fixing is particularly suitable for use as legs supporting a surface above the element 42. Thus, the fastener can secure a leg in an article of furniture, including a shelf.

As will be appreciated from the above discussion, the fastener is secured in the hole by friction and is prevented from being pushed out from the hole in the upwards direction by the flange 22 and is prevented from being pushed out from the hole in the downwards direction by the friction engagement between the fastener and the hole. In contrast, the prior art arrangements that use tapered fasteners that engage in tapered openings will only resist the removal of the fastener from the tapered opening in the upwards direction and will freely allow removal of the fastener in the downwards direction. The hole 44 can be a through hole (as shown in Figures 4 and 5), in which case, the top of the hole can be closed by a cap (not shown). Alternatively, the hole 44 could be a blind hole.