AU2010246511A1 - Bracket - Google Patents

Description

1 Bracket Field of the invention The present invention relates to a bracket and more particularly to a bracket for securing a wooden stair tread to a supporting structure, such as stairs or a ramp. 5 Background to the invention Attachment of a wooden tread to a stair stringer has been accomplished by a variety of mechanisms, such as by the use of fixings driven through a stringer into a tread (as shown in US Patent Application publication No. US2009056245A1), which also shows supporting the tread by the use of sub-tread wooden cleats. The trouble with this is that 10 there is a considerable opportunity for failure of the cleat and/or fixings as the surface area provided by these solutions is limited. The wood of the cleat and that around the fixings in the stringer can rot or otherwise weaken leading to an increased chance of failure of the tread. When failure of the tread does occur, the presence of sharp laterally projecting fixings can also cause lacerating injuries to a person. 15 Another solution is to increase the surface area of attachment of the stringer to the tread, such as described in patent publication GB2242919A, by routing or otherwise creating cut-outs in the stringer to accommodate the treads. Unfortunately, this is little better than the other attempts to solve this (above) and is subject to the same limitations. Additionally, removing material from the stringers can unacceptably 20 weaken them. Not removing enough material from the stringers provides insufficient support to the treads. Additionally, if the wood swells or shrinks prior to assembly, this 2 complicates assembly, requiring the need to hammer oversize treads into stringer slots or to enlarge the stringer slots. One of the biggest problems with the above wood-on-wood joints and supports is that wood can swell, rot, dry out or crack causing the joint or support to come under stress, 5 weaken and eventually fail. This has become particularly acute in recent times with the use of soft, fast-growing wood (like Pinus radiata) that is kiln-dried to rapidly dry the wood out and thereby accelerate the time from felling to market. If the kiln drying is too thorough or not thorough enough then the wood joints will come under stress over time as the wood swells or dries and can potentially fail. 10 The different parts of the wood grain also dry or swell after being dried in a different manner that can cause the wood to warp around knots and the natural rings in the wood by cupping, twisting or bowing. This is exacerbated in softer kiln-dried wood. As a partial solution to the wood-on-wood problem, metal brackets have also been used to support treads. There are a number of different types of these (e.g. 15 US2003029103A1 and US2002088669A1), but they function by permitting the tread to lie against a substantially flat top surface of the bracket. Fixings are driven through the tread and the bracket to secure the tread to the bracket. These brackets still have problems. The fixings represent a relatively small surface area of the tread and failure of the fixings or of the tread surrounding the fixings can still 20 lead to the tread failing. Additionally, warping of the wood can lead to the tread becoming uneven. Uneven treads are undesirable and can lead to injury of people using 3 the treads. In some cases, the warping puts sufficient strain on the fixings and surrounding wood that the bracket-tread joint fails. The use of brackets to support treads introduces an additional problem in that the brackets have to be levelled so the treads are level. A number of solutions have been 5 introduced to level the brackets. US2002088669A1, for example, uses a pre-assembled set of stringers that dynamically adjust the tread angle depending on the angle of the stairs to keep them level. However, this complicates matters where the brackets are installed directly onto a wall. US4631880A has a series of locating formations to adjust the tread angle. These formations are also potentially not strong enough and do not 10 permit fine adjustment of the angle. GB1245264A has a hinged tilting mechanism. However, over time, these moving parts can seize or slip. US2005236351A1 describes plastics moulded end caps for treads in portable steps for a spa pool. They have a closed structure completely encompassing the tread and do not permit different widths of tread to be used. The use of plastics materials is likely to be 15 insufficient to resist warping forces in larger wooden treads that are installed in buildings, potentially leading to failure of the caps if the treads do warp. They also have no way of adjusting the angle of the bracket as it is secured to a small rigid riser assembly. EP1748122A1 describes steps freely cantilevered from a building structure. Each step 20 is made up of multiple laminated glass panels attached to the wall by brackets. Each bracket has jaws with clamping bolts to tension the jaws against the step tread. There is no disclosure of a way to adjust the angle of the brackets and the bracket is specifically designed to engage with glass panels, not wooden treads.

4 It is therefore an object of the present invention to alleviate at least some of the problems identified above or to at least provide the public with a useful choice. Summary of the invention In a first aspect, the present invention provides a bracket for engaging at least one 5 wooden tread including at least the following: a) a body for attaching a tread to a supporting structure; b) the body having a tread channel, which channel is defined by a first tread supporting lip and a second tread supporting lip and a tread end stop; and c) a levelling formation located on the body that, in use, permits pivoting of the 10 body about the formation. In one embodiment, the bracket is adapted for engaging a single wooden tread. Alternatively, the bracket is adapted for engaging multiple wooden treads, such as foot bridges or ramps. Preferably the tread channel is open at at least one end, more preferably open at both 15 ends. This permits a tread of a larger width than the tread channel to be inserted into the tread channel. Preferably, each of the first tread supporting lip, the second tread supporting lip and the tread end stop have a substantially planar tread engaging surface, which surfaces are further preferably at substantially right angles to adjacent planar tread engaging 20 surfaces, thereby forming a substantially rectangular tread channel in cross section.

5 Preferably, there is sufficient distance between the first and second tread supporting lip planar tread engaging surfaces to receive a tread with a thickness in the range of 25 to 100 mm, more preferably with one of the following thicknesses: 25, 35, 45, 52, 75, 90 and 100mm. The sufficient distance may be chosen to permit wedging of a tread into 5 the channel. Alternatively, in a currently preferred embodiment, the sufficient distance may have some tolerance permitting a transitional or loose fit for a standard sized tread to permit slightly oversized or slightly warped treads to be received without modification. The bracket dimensions should preferably be made such that it is roughly proportional to the thickness of a tread being accommodated. 10 It is desirable to fix a tread into the channel. In one embodiment, therefore, at least one tread fixing formation is located within the channel, more preferably on the first or second tread supporting lips, most preferably, on the operatively lower supporting lip. The fixing formation can be any suitable formation that permits securing of the tread to the bracket. In a currently preferred embodiment, the tread fixing formation is a series 15 of tread fixing holes extending the length of the channel. The holes are suitable for receiving, for example, a fixing through them into a tread. Any suitable fixing may be used, such as nails or screws. The bracket can be manufactured from any sufficiently rigid and long-lasting material able to withstand and substantially suppress the warping forces experienced in a 20 wooden tread. The bracket must also be able to bear the forces transmitted from the tread when the tread is being loaded in use. High ductile and high tensile metals are preferred. In particular, the bottom and top lips and the bracket material between the top and bottom lips must be of a material able to withstand these forces.

6 In one embodiment, the bracket may be extruded. The extrusions are all drilled and de burred to form the finished bracket. The extrusion can be used to produce continuous lengths of bracket, with applications in non-limiting examples of foot bridges or ramps as a single continuous length. The limitations here are mainly practical lengths for 5 transportation. Standard lengths for the purposes of trucking are preferred, which are currently 5.4, 9, or 12m continuous lengths. Alternatively, an extruded length may be formed by cutting an extruded length into individual lengths, for use in non-continuous applications, like stairs. Marine-grade aluminium, galvanised steel and stainless steel are currently preferred 10 materials for the bracket. It is currently most preferred that T6 marine grade aluminium be used and preferably with a material thickness of 5mm. In an alternative embodiment to extrusion, the brackets may be manufactured in discrete units, more conveniently in non-continuous discrete units. Preferably, this is accomplished by the use of moulding. Moulds permit an entire bracket to be produced 15 without the need for further processing (e.g. drilling). A currently preferred material for moulded brackets is UV stabilised glass-reinforced plastics material. The levelling formation preferably has a pivot hole about which the bracket can be rotated. The pivot hole is preferably located such that the bracket's tendency to rotate of its own accord about the pivot hole, in use, is minimised. In a currently preferred 20 embodiment, the pivot hole is located on the tread end stop operatively above the center of mass of the bracket.

7 The levelling formation also preferably has a rotation arresting hole that permits the angle of the bracket to be set by securing a fixing through the hole once the operatively desired level has been attained. The bracket also preferably includes at least two supporting structure fixing formations. 5 In a prefered embodiment, these are holes located in the body. More preferably, there are two supporting structure fixing holes located proximal the ends of the tread channel. In a currently preferred embodiment, these two supporting structure fixing holes are located outside of the channel, more preferably on the operatively lower portion of the body. 10 A variety of sizes may be used for these holes, depending on the application. They should be chosen to be able to effectively secure the bracket to the supporting structure and bear the loads imparted to the bracket by the tread, in use. A typical example is a 15mm round hole that permits bolts to be inserted through the holes to secure the bracket to the supporting structure. 15 The supporting structure may be any structure where the bracket could be used. Non limiting examples of a supporting structure include walls and stringers. Applications that the bracket may be used in can be divided into two categories: stepped and continuous length. Non-limiting stepped examples include stairs and ladders. Non-limiting continuous length applications include ramps, boardwalks, 20 mezzanine floors, decks and footbridges. In continuous length applications, the bracket may be modified to suit the application by, for example, varying the overall size of the bracket and the size of tread it accommodates.

8 Depending on the application of the technology, the terminology for the tread and supporting structure may change, but the design principles are the same and are applicable to the present invention. An example of this is in the case of ladders, where the tread is a rung and the supporting structure is a ladder side rail. 5 In a further aspect, the present invention provides a method for attaching a wooden tread to a supporting structure including at least the steps of: a) providing a bracket of the first aspect of the invention; b) levelling the bracket against a supporting structure using the levelling formation; 10 c) securing the bracket to the supporting structure; and d) inserting an end of a tread into the tread channel such that it abuts against the tread end stop. Preferably, the step of levelling utilises the pivot hole. The bracket is rotated about the pivot hole until a desired level or orientation is achieved. 15 Levelling the bracket preferably includes the further step of arresting rotation of the bracket by use of the levelling formation, more preferably by driving a fixing through a rotation arresting hole into the supporting structure. In one embodiment, the bracket is secured to the supporting structure by binding it to the structure, more preferably by welding or adhering it to the structure. Welding is 20 particularly suitable if the supporting structure is composed of a weldable metal.

9 In an alternative embodiment, the securing of the bracket to the supporting structure is by way of use of at least two supporting structure fixing formations; more preferably, by driving a fixing through supporting structure fixing holes located in the body of the bracket; most preferably, by driving fixings through the two supporting structure fixing 5 holes located proximal the ends of the tread channel. Any suitable mechanical fixings can be used. Non-limiting examples include dynabolts, coach screws, or coach bolts, lag screws, lag bolts, or other mechanical fixings in any screw pattern to suit the application needed. Or it could be welded to a steel stringer if so desired. Preferably, the fixings used for securing of the bracket to the 10 supporting structure are bolts, more preferably blind bolts. Applications that the bracket may be used in can be divided into two categories: stepped and continuous length. Non-limiting stepped examples include stairs and ladders. Non-limiting continuous length applications are ramps, boardwalks, trestles, mezzanine floors, decks and footbridges. In continuous length applications, the bracket 15 may be modified to suit the application by, for example, varying the overall size of the bracket and the size of tread it accommodates. Accordingly, the supporting structure may be any structure that a stepped or continuous length application requires. Non limiting examples include walls, stringers, side rails, plinths and stiles. Depending on the application of the technology, the terminology for the tread and 20 supporting structure may change, but the design principles are the same and are applicable to the present invention. An example of this is in the case of ladders, where the tread is a rung and the supporting structure is a ladder side rail.

10 If the tread width is greater than the tread channel length then the tread is preferably permitted to extend beyond the tread channel while a portion of its width is housed within the tread channel. A variety of tread widths can be used with the bracket of the invention. Currently 5 preferred tread widths are in the range of 250 to 800mm, more preferably: 250, 300, 400, 600, and 800mm. In one embodiment, the bracket is provided such that the tread is inserted in a transitional fit into the tread channel. In one embodiment, the method includes the additional step of fixing the tread into the 10 channel; more preferably, by use of the at least one tread fixing formation; most preferably by driving fixings through tread fixing holes into the tread. Brief description of the drawings The invention will be described below with reference to a non-limiting examples and the accompanying drawings, wherein: 15 Fig. 1 is a perspective left hand side slightly vertically elevated view of a bracket of the invention; Fig. 2 is a sectional side view of a bracket of the invention when assembled with its tread and a wall; Fig. 3 is a perspective left hand underside view of a bracket of the invention when 20 assembled with its tread and a wall; 11 Fig. 4 is a cut-away frontal view of an extrusion die for producing extrusions suitable for modification to brackets of the present invention; and Fig. 5 is a perspective view of an individual extruded bracket of the present invention. Examples 5 Example 1: Bracket and use thereof Figure 1 is a perspective left hand side slightly vertically elevated view of a bracket in its unassembled state. With reference to Figure 1: A bracket, generally indicated by 100, has a body, generally indicated by 110, of 3mm galvanised steel. The body 110 has a tread channel, generally indicated by 120, defined 10 therein. The tread channel 120 has a tread upper supporting lip 130 (having a planar tread engaging surface 140 on its lower surface), and a tread lower supporting lip 150 (having a planar tread engaging surface 160 on its upper surface). The tread channel connects the upper and lower tread supporting lips by a tread end stop 170, which also has a planar tread engaging surface 180. The channel ends, generally indicated as 190 15 and 200, are open. The distance between the planar tread engaging surfaces of the upper and lower tread supporting lips 140 and 150 is 47.5mm. The bracket 100 also has a levelling formation in the form of a chamfered pivot hole 210 and a chamfered rotation arresting hole 220 located in the tread channel 120. Also 20 included on the body 110 below the lower tread supporting lip 150 is a flange 230 with 12 a first mounting hole 240 and a second mounting hole 250 located therein, each of 15mm diameter. The lower tread supporting lip 150 also includes four chamfered tread fixing holes 260, 270, 280 and 290 evenly spaced along its length. 5 The use of the above-described bracket will now be described with reference to all drawings. Figure 2 is a sectional side view of a bracket 100 when assembled with a tread 300 and a wall 310. The section line is through the pivot hole 210 of the bracket 100 depicted in Figure 1. The tread 300 and wall 310 are cut-away, showing only pertinent features. 10 Figure 3 is a perspective left hand underside view of the bracket 100 when assembled with the tread 300. The tread 300 is cut-away, showing only pertinent features. In all cases, identical features visible in all three drawings have been marked with the same reference numerals. In use, a bracket 100, is affixed to the wall 310 by first locating the bracket at a suitable 15 position on the wall 310 and driving a pivot screw 320 through the pivot hole 210 into the wall 310. The pivot screw 320 is not driven in completely, thereby permitting the bracket 100 to be pivoted around the pivot screw 320 by a user (not shown). The bracket 100 is pivoted until a desired angle for the tread channel 120 is reached. Conveniently, a spirit level or other levelling device (not shown) may be inserted into 20 the channel 120 or placed on top of the tread upper supporting lip 130 to determine the 13 desired angle or level. Once a desired angle is attained, the angle is set by driving a rotation resisting screw (not shown) into the wall 310 through the rotation arresting hole 220. Holes are drilled through the mounting holes 240 and 250 into the wall 310 and blind 5 bolts 330 and 340 are inserted through the mounting holes 240 and 250 into the wall 310 and tightened to secure the bracket 100 to the wall 310. The tread 300 has a standard thickness of 45mm. An end (generally indicated as 350) of the tread 300 is inserted into the tread channel 120 such that it abuts against the tread end stop planar tread engaging surface 180. The three planar tread engaging surfaces 10 140, 160 and 180 cooperate to engage the tread end 350. The tread end 350 is held in a transitional fit in the channel. Warping of the tread is thereby substantially diminished. Tread fixing screws 360, 370, 380 and 390 are driven through the tread fixing holes 260, 270, 280 and 290 into the tread end 350, thereby fixing the tread 300 to the bracket 100. 15 Example 2: Manufacture of bracket With reference to Fig. 4, a die (partially shown as 400) is used to extrude T6 aluminium brackets with a profile as shown at 410 using well-known techniques in the aluminium extrusion industry. T6 aluminium alloy is also known as 6061-T6 and has the following chemical makeup (% by weight): Al 95.8-98.6%, Cr 0.04-0.35%, Cu 20 0.15-0.40%, Fe 0-0.70%, Mg 0.8-1.2%, Mn 0-0.15%, Si 0.4-0.8%, and Zn 0-0.25%.

14 This produces lengths of extruded 5mm material thickness aluminium (not shown), suitable for modification to brackets in lengths chosen to be 5.4, 9, or 12m, depending on client and transportation requirements. With reference to Fig. 5, the above process equally allows for the production of 5 individual brackets for holding stair treads, as generally shown as 500. The extruded bracket 500 is finished by de-burring, smoothing and hole formation. De burring involves the process of removing any rough spots from the extrusion. Corners 510, 520, 530, 540, 550 and 560 are smoothed by rounding them. 15mm diameter holes 240 and 250 are drilled and countersunk holes (4mm diameter 10 with 8mm countersunk maximum diameter) 7210, 220, 260, 270, 280 and 290 are formed. Modifications can be made to the above without departing from the scope of the invention. In particular, continuous lengths may be similarly finished as described above with reference to the bracket shown in Fig. 5, and moulded materials may be 15 used to produce the brackets of the invention.

Claims (39)

1. A bracket for engaging at least one wooden tread including at least the following: a) a body for attaching a tread to a supporting structure; 5 b) the body having a tread channel, which channel is defined by a first tread supporting lip and a second tread supporting lip and a tread end stop; and c) a levelling formation located on the body that, in use, permits pivoting of the body about the formation.

2. A bracket as claimed in claim 1, wherein the bracket is adapted for engaging a 10 single wooden tread.

3. A bracket as claimed in claim 1 or claim 2, wherein the tread channel is open at at least one end.

4. A bracket as claimed in any one of the preceding claims, wherein the tread channel is open at both ends thereof. 15

5. A bracket as claimed in any one of the preceding claims, wherein each of the first tread supporting lip, the second tread supporting lip and the tread end stop have a substantially planar tread engaging surface.

6. A bracket as claimed in claim 5, wherein each of the first tread supporting lip, the second tread supporting lip and the tread end stop are at substantially right angles to 16 adjacent planar tread engaging surfaces, thereby forming a substantially rectangular tread channel in cross section.

7. A bracket as claimed in any one of the preceding claims, wherein there is sufficient distance between the first and second tread supporting lip planar tread engaging 5 surfaces to receive a tread with a thickness in the range of 25 to 100 mm in a fit selected from the group consisting of: a tight fit arrangement, a transitional fit arrangement and a loose fit arrangement.

8. A bracket as claimed in claim 7, wherein there is sufficient distance between the first and second tread supporting lip planar tread engaging surfaces to receive a 10 tread with a standard thickness selected from the group consisting of: 25, 35, 45, 52, 75, 90 and 100mm.

9. A bracket as claimed in any one of the preceding claims, wherein at least one tread fixing formation is located within the channel.

10. A bracket as claimed in claim 9, wherein the at least one tread fixing formation is 15 located within the channel on the first or second tread supporting lips.

11. A bracket as claimed in claim 10, wherein the at least one tread fixing formation is located within the channel on the first or second tread supporting lips.

12. A bracket as claimed in claim 11, wherein the at least one tread fixing formation is located on an operatively lower supporting lip. 17

13. A bracket as claimed in any one of claims 9 to 12, wherein the fixing formation is a series of tread fixing holes extending the length of the channel.

14. A bracket as claimed in any one of the previous claims, wherein the bracket is extruded. 5

15. A bracket as claimed in claim 14, wherein the extruded bracket is substantially composed of a material selected from the group consisting of: galvanised steel, stainless steel, and marine-grade aluminium.

16. A bracket as claimed in any one of claims 1 to 13, wherein the bracket is moulded.

17. A bracket as claimed in claim 16, wherein the moulded bracket is composed of UV 10 stabilised glass-reinforced plastics material.

18. A bracket as claimed in any one of the preceding claims, wherein the levelling formation has a pivot hole about which the bracket can be rotated.

19. A bracket as claimed in claim 18, wherein the pivot hole is located such that the bracket's tendency to rotate about the pivot hole in use is minimised. 15

20. A bracket as claimed in claim 18 or claim 19, wherein the pivot hole is located on the tread end stop operatively above the center of mass of the bracket.

21. A bracket as claimed in any one of the preceding claims, wherein the levelling formation has a rotation arresting hole that permits the angle of the bracket to be set by securing a fixing through the hole once the operatively desired level has been 20 attained. 18

22. A bracket as claimed in any one of the preceding claims, wherein the bracket includes at least two supporting structure fixing formations.

23. A bracket as claimed in claim 22, wherein the at least two supporting structure fixing formations are holes located in the body. 5

24. A bracket as claimed in claim 23, wherein the supporting structure fixing holes are two holes located proximal the ends of the tread channel.

25. A bracket as claimed in claim 24, wherein the supporting structure fixing holes are two holes located proximal the ends of the tread channel.

26. A bracket as claimed in claim 25, wherein the two supporting structure fixing holes 10 are located outside of the channel on an operatively lower portion of the body.

27. A method for attaching a wooden tread to a supporting structure including at least the steps of: a) providing a bracket as claimed in any one of claims 1 to 26; b) levelling the bracket against a supporting structure using the levelling 15 formation; c) securing the bracket to the supporting structure; and d) inserting an end of a tread into the tread channel such that it abuts against the tread end stop. 19

28. A method according to claim 27, when using a bracket as claimed in any one of claims 18 to 26, including the step of levelling utilising the pivot hole as a fulcrum until a desired level or orientation is achieved.

29. A method according to claim 27 or claim 28, when using a bracket as claimed in 5 any one of claims 18 to 26, including the step of arresting rotation of the bracket by use of the levelling formation.

30. A method according to claim 29, when using a bracket as claimed in any one of claims 21 to 26, including the step of arresting rotation of the bracket by driving a fixing through a rotation arresting hole into the supporting structure. 10

31. A method according to any one of claims 27 to 30, wherein the bracket is secured to the supporting structure by binding it to the structure by welding or adhering it to the structure.

32. A method according to any one of claims 27 to 30, wherein the bracket is secured to the supporting structure use of at least two supporting structure fixing 15 formations.

33. A method according to claim 32, when using a bracket as claimed in any one of claims 24 to 26 by driving a fixing through the supporting structure fixing holes located in the body of the bracket.

34. A method according to any one of claims 27 to 33, wherein the method includes the 20 additional step of fixing the tread into the channel. 20

35. A method according to claim 34, when using a bracket as claimed in any one of claims 9 to 26, wherein the fixing the tread into the channel is performed by use of the at least one tread fixing formation.

36. A bracket, substantially as herein described with reference to any example thereof. 5

37. A bracket, substantially as herein described with reference to any example thereof with reference to the drawings.

38. A method for attaching a wooden tread to a supporting structure substantially as herein described with reference to any example thereof.

39. A method for attaching a wooden tread to a supporting structure substantially as 10 herein described with reference to any example thereof with reference to the drawings.