ShrinkLock Washer

Field of Invention

The invention relates to a shrink lock washer for preventing and/or lessening the effect of timber shrinkage in building or like structures.

Background of Invention

The majority of buildings are either made entirely of timber or use timber as part of the materials in the buildings construction. Timber can be used in the construction of floors, walls, roofs, ceilings and other load bearing applications. As such the movement of individual pieces of timber relative to another piece of timber (or structural member) in a constructed building is generally unwanted and not desirable, especially where that timber is used in a load bearing capacity such as part of a roof structure, subfloor structure or a wall.

Most timber is substantially dried before use, however not all timber is completely dry and not all timber is dried to the same level, as such the timber is still drying after a building has been constructed and a degree of timber shrinkage can and does occur. Also with the demand on timber ever increasing it is not uncommon for "green" timber or partially dried timber to be used during construction. During the proceeding years after construction timber dries and shrinks causing movement and or warping of timber relative to one another. Thus leading to cracks appearing in walls, floors and ceilings or in the worst case scenario failure of a load bearing structure, such as a wall.

Also buildings move during earthquakes and high winds, thus applying stress to the timber used and can cause the timber to move relative to one another or the supporting member it is connected to.

When earthquakes or high winds occur, following timber shrinkage, the fixings, which fix the timber together or to structural members, become loose or stressed or fail and as such they do not perform as they should.

There have been many attempts to overcome the above problems associated with the effects of timber shrinkage. These range from increasing the effectiveness of drying timber to using

a spring between the nut and washer applied to a bolt used to fasten timber to one another or fasten the timber another structural member. However none of these address the problem satisfactorily or effectively.

Object of the Invention

It is an object of the invention to provide a shrink lock washer, for preventing and/or lessening the effect of timber shrinkage occurring in building or like structures, which ameliorates some of the disadvantages and limitations of the known art or at least provide the public with a useful choice.

Summary of invention.

In a first aspect the invention resides a shrink lock washer for preventing and/or lessening the effect of timber shrinkage or movement occurring in building or like structures, wherein the shrink lock washer including, in combination: i) an upper washer portion adapted to be attached to a fastener for fastening timber to another piece of timber and/or to a structural member, ii) an lower washer portion adapted to position beneath and moveable relative to the upper washer portion, and iii) a biasing portion connectable to the lower washer portion and fϊxable to the timber such that the biasing action of the biasing portion urges the lower portion toward and under the upper washer portion such that when timber shrinkage or movement thereof occurs the shrink lock washer is adapted to accommodate for that shrinkage and/or relative movement of the timber relative to the other timber or structural member to which the timber is fastened.

Preferably, the shrink lock washer further includes a base plate adapted to be positioned between the lower washer portion and the timber, wherein the base plate is adapted to prevent the lower portion moving away for the upper washer portion.

Preferably, the biasing portion is a spring.

Preferably, the spring is sprung steel.

Preferably, the spring is u-shaped in cross-section, wherein legs of the 'u' are adapted to bias away from each other.

Preferably, the spring has a holding means adapted to allow legs of the 'u' to be bought together against the bias.

Preferably, the spring has holes therein adapted to co-operate with the holding means in order to bring the leg of the 'u' together.

Preferably, the holding means is a screw.

Preferably, the holding means is wire, string, tie or similar holding means.

Preferably, the holding means is a clamp.

Preferably, the upper washer portion and the lower washer portion have co-operating inclined surfaces such that the lower washer portion is able to move underneath the upper washer portion.

Preferably, the inclined surfaces have co-operating teeth such that the lower washer portion is adapted to move in only one direction.

Preferably, the lower washer portion and the upper washer portions are made from any suitable materials, such as, steel, metal, wood, plastic, fibre glass, ceramics, rubber or composites thereof.

Preferably, the biasing portion is made from any suitable biasing material, such as sprung steel, sprung metal, electrometric materials, rubber, plastics or composites thereof.

In a second aspect the invention resides a shrink lock washer for preventing and/or lessening the effect of timber shrinkage or movement occurring in building or like structures, wherein the shrink lock washer including, in combination:

- A - i) an upper washer portion adapted to be attached to a fastener for fastening timber to another piece of timber and/or to a structural member, ii) a lower washer portion adapted to position beneath and moveable relative to the upper washer portion, and iii) a biasing portion connectable to the lower washer portion and fϊxable to the timber such that the biasing action of the biasing portion is adapted to cause the shrink lock washer to compensate for timber shrinkage or other movement of the timber.

In other aspects herein described

Brief Description

The invention will now be described, by way of example only, by reference to the accompanying drawings:

Figure 1 is a side view of an upper portion of the shrink lock washer in accordance with a first preferred embodiment of the invention.

Figure 2 is a top view of the upper portion shown in figure 1.

Figure 3 is a side view of a lower portion of the shrink lock washer in accordance with a first preferred embodiment of the invention.

Figure 4 is an end view of the lower portion shown in figure 3. Figure 5 is a top view of the lower portion shown in figure 3.

Figure 6 is a side view of a base plate for the shrink lock washer in accordance with a first preferred embodiment of the invention.

Figure 7 is a top view of the base plate shown in figure 6.

Figure 8 is a side view of the spring portion of the shrink lock washer in accordance with a first preferred embodiment of the invention.

Figure 9 is a top view of the spring portion shown in figure 8.

Figure 10 is a side view an assembled shrink lock washer with the spring portion un- tensioned in accordance with a first preferred embodiment of the invention.

Figure 11 is a side view an assembled shrink lock washer with the spring portion tensioned in accordance with a first preferred embodiment of the invention.

Description of Drawings

The following description will describe the invention in relation to preferred embodiments of the invention, namely a shrink lock washer. The invention is in no way limited to these preferred embodiments as they are purely to exemplify the invention only, and that possible variations and modifications would be readily apparent without departing from the scope of the invention.

The shrink lock washer consists of three major portions, these being an upper washer portion, a lower washer portion and a biasing portion integral with or attachable to the lower washer portion. The shrink lock washer is designed to be attachable to any sort of fastening device used to fix timber to one another or to any other structural element, such as nut and bolt assembly or even a nail. The drawings will be described in relation to the shrink lock washer used with a nut and bolt assembly for securing a timber bottom plate to a joist. However it would be readily envisaged that other applications of the washer are possible and would clearly and readily be apparent to a skilled addressee without departing from the scope of the invention.

Figures 1 & 2 shows the upper washer portion 1 having a fastening receiving aperture 2. The upper washer portion 1 has an inclined bottom surface that slidingly co-operates with an upper surface of the lower washer portion. Preferably the upper washer portion 1 is of a wedge shape.

Figures 3, 4 & 5 show the lower washer portion 5 having an elongated fastening receiving aperture 4. The lower washer portion 1 has an inclined upper surface that slidingly co- operates with a bottom surface of the upper washer portion 1. Preferably the lower washer portion 1 is also of a wedge shape. The lower portion 5 is shown as having a slot 3 in an end wall which is adapted when in use to receive and hold a part of the biasing portion to the lower portion. However it is also envisaged that the biasing portion can be integral with the lower washer portion 5.

The inclined surfaces of the bottom and upper washer portions can have co-operating teeth, such that when in use the inclined surface of one of washer portions is able to move only in

one direction relative to the other, i.e a ratcheting effect to prevent the washer portions from slipping and returning to their original starting positions relative to one another.

Figures 6 & 7 show a base plate 6 having flat surface and a raised wall portion 6A. The base plate 6 has a fastening receiving aperture 7. In use, the base plate 6 accommodates the lower washer portion 5 on its flat surface such that the wall 5A abuts the raised wall portion 6A so as to prevent the lower washer portion 5 sliding in a direction away from the upper washer portion 1. The base plate 6 is an optional feature and other ways of preventing movement of lower washer portion 5 away from the upper washer portion 1 are envisaged such as placing and fixing a stopper, such as screw, nail, pin, abutment, to the timber approximate to the wall 5A of the lower washer portion.

Figures 8 & 9 show a biasing portion 8, preferably a steel spring. The biasing portion 8 is shown as generally having an inverted. u-shape cross-section with one leg of the u-shape being longer than the other. The biasing action of the biasing portion 8 will bias the legs of the u-shape away from each other. The ends of the legs have flanges 8 A and 8B extending generally transverse to the legs and extending in opposite direction to one another. Flange 8 A is adapted to co-operate and be held in slot 3 of the wall 5 A of the lower washer portion 5. Flange 8B has holes 11 through such that in use a fastener such as a nail 13 is able to be inserted so as to fasten the biasing portion to the timber. The biasing portion 8 has holes 9 in its legs so as to assist the legs to be drawn together and held against the biasing action of the biasing portion 8. As shown, a screw 10 is adapted to be inserted into the holes 9 in order to draw and hold the legs of the biasing portion together. It is foreseeable that other holding means can be used to draw and hold the legs towards one another, such as wire, string, tie, clamp or other suitable retaining means. Once the biasing means 8 is held in place to the lower washer portion and fixed to the timber, the holding means, e,g screw 10 is removed. Preferably the biasing portion 8 is made from sprung steel, however other types of biasing portions are envisaged such as leaf spring, coiled spring, etc and can be made from any suitable material, such as plastics, metal, rubber and/or composite thereof.

Figures 10 shows the shrink lock washer positioned on a bolt/nut assembly prior to the biasing means being biased and fixed to a piece of timber 13 A. The base plate 6 is placed on the bolt to rest on the timber 13A. The lower washer portion 5 with the elongated hole 4,

which allows the lower washer portion 5 to move forwards under pressure from spring 8 when timber shrinkage occurs, is placed on the bolt to rest on top of the base plate 6 and wall 5A of the lower washer portion abuts the raised wall 6A. Then upper washer portion 1 is placed on lower washer portion 5 and the nut tightened down. A co-operating end of the biasing portion 8 is then situated in slot 3 in the wall of the lower washer portion 8. Turning to figure 11, the screw 10 is inserted and wound through holes 9 in the biasing portion 8 so as to compress the biasing portion 8 together. Once compressed the biasing portion 8 is then fixed with a nail 13 or screwed into the timber through hole(s) 11 in the biasing portion 8 which then puts pressure on the upper and lower washer portions 1, 5 and takes up any shrinkage. After the biasing portion 8 is secured to the timber, screw 10 is then removed. When shrinkage occurs, the biasing portion 8 forces the lower washer portion 5 under the upper washer portion 1 taking up any slack in shrinking timber.

The upper and lower portions are preferably made from galvanised steel, however other suitable materials can be used, such plastic, fibre glass, wood, metals, rubber, etc.

Flange 8B can include other suitable means in order to fasten it to the timer, such an adhesive strip on its under surface or provided with integral nails (e.g. similar to a nail plate arrangement) on its under surface such that when in the desired position the flange 8B is hammered into place.

List of components and items used in drawings:

1. Upper Washer Portion

2. 12mm Hole In Upper Washer Portion

3. Slot Cut In Lower Washer Portion To Accommodate Spring

4. Elongated Hole In Lower Washer Portion

5. Lower Wedge Washer Portion

5A. Wall Of The Lower Washer Portion

6. Base Plate

6A. Raised Wall

7. Hole In Base Plate

8. Basing Portion

8A Flange

8B Flange

9. Hole In Spring To Accommodate Screw

10. Screw

11. Hole(s) In Spring

13. Nail Or Screw To Fix Spring Steel To Timber

13 A Timber Bottom Plate

Advantages a) Less movement in earthquake and high winds of braced structures b) The wedge washer self tightens in inaccessible areas c) Limits excessive stress and forces to other building materials. d) Easy to assemble and use e) Able to be readjusted after shrinkage or movement

Variations

Throughout the description of this specification, the word "comprise" and variations of that word such as "comprising" and "comprises", are not intended to exclude other additives, components, integers or steps.

It will of course be realised that while the foregoing has been given by way of illustrative example of this invention, all such and other modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is hereinbefore claimed in the appended claims.