AU730476B2 - Improvements in key joints for slabs - Google Patents

Description

P/00/01i1 Regulation 3.2

AUSTRALIA

Patents Act 1990 a a.

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "IMPROVEMENTS IN KEY JOINTS FOR SLABS" The following statement is a full description of this invention, including the best method of performing it known to me: |u 2 THIS INVENTION relates to improvements in key joints for slabs.

Because concrete undergoes thermal expansion and contraction, it is necessary to provide expansion joints or breaks in concrete slabs, footpaths and the like to at least minimise unwanted cracking in the concrete.

For example, it is common practice to provide expansion joints or break lines every 1.0 to 1.5 metres along footpaths.

°"Many different key joint systems have been disclosed i' 10 where a joint plate is supported by a plurality of spaced stakes. It is necessary that vertical adjustment is possible between the joint plate and the stakes so that the height of the plate can be selectively adjusted.

Examples of adjustable connection between the plate and the stakes is disclosed in US 4411404 and US 4455104 (ALBERT P. WEISBACH); AU-B-36515/89 (604612) (PAUL F. CONNOLLY et al) and AU-B-28152/92 (666883) (DANIEL C. UNDERWOOD). In the US Patents of WEISBACH, the top end of each stake is flattened and has a plurality of closely spaced, vertically arranged serrations formed on one side to releasably engage the hem of a downturned flange on the joint plate, the edge of the hem serving as a locking pawl for cooperating with the serrations. In AU-B-36515/89, wedges are engaged between a central portion of the plate and respective stakes 3 to releasably lock the plate to the stakes. In AU-B-28152/92 (UNDERWOOD), the stakes pass through pairs of aligned, elongate apertures in the plate and are rotatable through 900 so that formations on the sides of the stakes releasably engage sides of the apertures to secure the plates to the stakes.

It is an object of the present invention to provide alternative means for releasably securing the stakes to the key joint plate.

It is a preferred object of the present invention to provide 10 such means which allow easy adjustment of the plate to the stakes when the key joint assembly is being set up which will prevent accidental or unwanted adjustment of the plate relative to the stakes.

It is a further preferred object of the present invention to oil• **provide stakes which can be adapted to suit a wide range of applications, eg., where a slab is to be poured on an existing slab.

Other preferred objects of the present invention will become apparent from the following description.

Throughout the specification, the term "a keyed joint plate assembly for concrete of the type hereinbefore described" shall include: "a joint plate having substantially co-planar, vertical top and bottom sections interconnected to a rearwardly-spaced central section by rearwardly-convergent upper and lower inclined sections, a plurality of pairs of holes spaced along the plate, the holes from each pair being provided respectively in the upper and lower inclined sections in substantially vertical alignment to each other, and a substantially horizontal top edge; and a plurality of stakes to support the plates substantially vertically, each stake passing through a respective pair of the vertically aligned holes." Such definition is based on Claim 1 of parent Patent No. 604612.

In a broad aspect, the present invention resides in a 10 keyed joint plate assembly for concrete as hereinbefore defined, .o wherein: a cam means has a finger portion adapted to be engaged between the central portion of the plate and each stake, a handle means and a torsion means interconnecting the finger to the handle means, so arranged that: as the handle is rotated, the finger releasably locks the plate to the stake.

Preferably, at least one of the holes may have an integral resilient finger means adapted to urge the stake towards the central section of the plate.

To enable the invention to be fully understood, a preferred embodiment will now be described with reference to the accompanying drawings in which: FIGS. 1 and 2 are respective rear and front perspective views of a keyed joint assembly of a first embodiment; FIG. 3 is a sectional side view of the joint plate of the first embodiment; FIGS. 4 and 5 are respective rear and front perspective views of a keyed joint assembly of the second embodiment; FIG. 6 is a sectional end view of the keyed joint of the second embodiment; FIGS. 7 and 8 are respective rear and front perspective 10 views of the keyed joint assembly of a fourth embodiment; FIG. 9 is a sectional end view of the joint plate of the oleo third embodiment; FIGS. 10 and 11 are respective rear and front ~perspective views of the keyed joint assembly of a fourth embodiment; FIG. 12 is a sectional end view of the joint plate of the fourth embodiment; FIGS. 1 and 2 are respective rear and front perspective views of the keyed joint assembly of a first embodiment; FIG. 3 is a sectional end view of the joint plate of the fifth embodiment; and FIG. 4, views A to C are respective side, top plan and end views of the cam means of the fifth embodiment.

a :6 6 Referring to FIGS. 1 to 3, the joint plate 410 has respective, substantially co-planar, vertical top and bottom sections 411, 412 interconnected to a planar central section 413 by rearwardly convergent upper and lower inclined sections 414, 415.

Aligned holes 416, 417 are formed in the inclined portions 414, 415 to receive a stake 420, the upper hole 416 having a resilient finger 418 adapted to urge the stake 420 towards the central section 413.

A cam member 470, shown in views A to C in FIG. 16 S•°:has a substantially flattened finger portion 471 connected to a handle 10 472 by an L-shaped torsion member 473. In use, the finger 471 is inserted between the stake 420 and the central portion 413 of the *ooo plate 410 and the handle is pulled downwardly to cause torsional twisting of the finger relative to the handle 472 via the torsion body 473. The handle goes "over-centre" and engages the lower inclined portion 415 to the joint plates 410 to lock the cam means 470 in place. The pressure of the finger portion 471 on the stake 420 releasably locks the plate 410 to the stake 420.

The cam means may be formed of suitable metal, eg., spring steel, or plastics fibre-reinforced) material.

Preferably, the joint plates are roll-formed from metal strip, with safety edges top and bottom and may have reinforcing ribs in the top handle bottom sections. Alternatively, joint plates may be, eg., extruded from suitable plastics material.

7 The stakes may be formed from steel rod, eg., with digging points at their lower end or may be moulded from suitable plastics material.

It will be readily apparent to the skilled addressee that the joint plate may have a range of profiles.

Various changes and modifications may be made to the embodiments described and illustrated without departing from the present invention.

.1

Claims (3)

1. A keyed joint plate assembly as hereinbefore defined, wherein: a cam means has a finger portion adapted to be engaged between the central portion of the plate and each stake, a handle means and a torsion means interconnecting the finger to the handle means, so arranged that: as the handle is rotated, the finger releasably locks the plate to the stake. 10

2. An assembly as claimed in Claim 1 wherein: at least one of the holes has an integral resilient finger means adapted to urge the stake towards the central section of the plate.

3. A keyed joint plate assembly for concrete substantially as hereinbefore described with reference to FIGS. 1 to 4 of the accompanying drawings. DATED this fifth day of June 2000. PAUL FRANCIS CONNOLLY and ALMA IRENE CONNOLLY By their Patent Attorneys FISHER ADAMS KELLY