The term"screw pile anchors"shall also include"screw piers"and"ground anchors".

2. Prior Art AU-B-17734/95 (680352) (PAUL CAMILLERI) discloses the manufacture of ground anchors, or screw piers, where the helical flyte is formed by deformation of the tubular shank.

AU-A-40280/95 (STEEL FOUNDATIONS LIMITED) discloses the manufacture of screw piers, where preformed helical flytes are welded to the tubular body of the piers using a welding machine.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for manufacturing the helical flytes where the flytes can be cut as a blank from a metal sheet and welded to the shafts or tubular body of the anchors.

It is a preferred object of the present invention to provide such flytes which incorporate reinforcing ribs or flanges.

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

In one aspect, the present invention provides a method of forming a helical flyte for a screw pile anchor, including the steps of: a) cutting the blank, with a central hole, from a metal sheet; b) cutting a plurality of substantially radial slits in the blank from the central hole; c) deforming a plurality of tabs, defined by adjacent pairs of the slits, out of the plane of the blank; and d) deforming the blank into a substantially helical

configuration.

Preferably, the method further includes step (e) wherein a radial slit is cut in the central hole to the periphery before step (d).

Step (d) may be effected before step (c) if preferred.

In a second aspect, the present invention resides in a helical flyte for a screw pile anchor including: a metal body of helical configuration about a central hole; and a plurality of tabs defined by adjacent pairs of substantially radial slits from the central hole, tabs being deformed out of the plane of the adjacent portions of the body.

In a third aspect, the present invention resides in a method of forming a helical flyte for a screw pile anchor including the steps of: a) cutting a blank, with a central hole, from a metal sheet; b) forming a plurality of substantially radial deformations out of the planes of the respective adjacent portions of the blank; and c) deforming the blank into a substantially helical configuration.

The method may include a further step (d) where a radial slit is cut from the central hole to the periphery of the blank before step (c).

Preferably, the deformations are of reducing width and height (or radius) in the radially upward direction.

Preferably, the deformations terminate a distance from the periphery of the flyte.

In a fourth aspect, the present invention resides in a helical flyte for a screw pile anchor including: a metal body of substantially helical configuration about a central hole; and a plurality of substantially radial deformations formed out of the planes of adjacent portions of the body.

In a fifth aspect, the present invention resides in a method of

forming a helical flyte for a screw pile anchor including the steps of: a) cutting a first blank, with a central hole, from a metal sheet; b) deforming the first blank into a substantially helical configuration; and c) cutting a second blank, of reduced diameter, with a central hole, from a metal sheet; d) deforming the second blank into a substantially helical configuration; e) locating the second blank above the first blank with the respective central holes co-axial; and f) welding, brazing or otherwise fastening the periphery of the second blank to the upper surface of the first blank.

Preferably, the second blank, on a radial line, is inclined at an angle of 10°-30° relative to the first blank.

Preferably, the method includes a further step (a1) where a radial slit is cut from the central hole to the periphery of the first blank, before step (b); and a further step (c1), where a radial slit is cut from the central hole to the periphery of the second blank, before step (d).

In a sixth aspect, the present invention resides in a helical flyte manufactured by the method of the fifth aspect.

The helical flyte may be substantially circular, square, hexagonal, octagonal or other shape in plan view; and is preferably fixed to the shaft or tubular shank of the screw pile anchor by welding of the tabs or deformations and/or the internal periphery of the central hole to the shaft or body.

BRIEF DESCRIPTION OF THE DRAWINGS To enable the invention to be fully understood, preferred embodiments will now be described with reference to the accompanying drawings, in which: FIG. 1 is a plan view of the helical flyte in accordance with the first embodiment;

FIG. 2 is a side elevational view thereof; FIG. 3 is a perspective view thereof; FIG. 4 is a sectional view taken on line A-A in FIG. 1; FIG. 5 is a perspective view of the helical flyte in accordance with the second embodiment; FIG. 6 is a side elevational view thereof; FIG. 7 is a perspective view showing the helical flyte attached to a tubular shaft of the screw pile anchor; FIG. 8 is a perspective view of the helical flyte in accordance with the third embodiment; FIG. 9 is a top plan view thereof; FIG. 10 is a sectional view taken on line A-A on FIG. 8; FIG. 11 is one side elevational view thereof; and FIG. 12 is a second side elevational view thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 to 4, the helical flyte 10 is substantially octagonal in plan view (with rounded corners) and is formed from a sheet metal blank 11 cut from a piece of metal sheet.

A central hole 12 is provided in the blank and a plurality of substantially radially extending slits 13 extend therefrom, terminating a distance from the periphery 14 of the flyte.

Respective tabs 15, defined by adjacent pairs of slits 13, are bent out of the planes of the respective adjacent portions of the body 11, and as shown in FIGS. 2 to 4, are preferably deformed alternately upwardly and downwardly relative to the body 11.

A radial slit is cut from the central hole 12 to the periphery 14, and this defines the leading edge 16 and trailing edge 17 of the flyte 10 when it is deformed into the helical configuration.

The helical flyte 10 is attached to the tubular shaft (not shown) of the screw pile anchor (also not shown) by welding the inner edges 18 of the tabs 15 to the tubular shaft. The alternative inclination of

the tabs 15 provides bracing to the flyte 10 to ensure that it can sustain high vertical loads along the tubular shaft.

In the helical flyte 20 of the second embodiment in FIGS. 5 and 7, a plurality of substantially part-conical formations 25 extend substantially radially from the central hole 22 in the body 21 of the helical flyte.

Each formation 25 is of reducing width and height (or radius) in the radially-outward direction, and the helical flyte 20 is secured to the tubular shaft 30 (see FIG. 7) by welding the shaft 30 to the faces 28 of the formations 25 and the central hole 22.

Again, the formations 25 provide rigidity and stiffness to the helical flyte 20.

Referring to FIGS. 8 to 12, the helical flyte 120 of the third embodiment is formed from a first blank 121, of substantially octagonal shape, with a central hole 122, and radial slit 123, formed into a substantially helical formation.

A second blank 124 of substantially circular shape, has a central hole 125 and a radial slit 126 and is also formed into a substantially helical shape.

The second blank 124 is placed on the first blank 121, with the central holes 122,125 co-axial.

The periphery 127 of the second blank is welded, brazed or otherwise fastened to the upper face of the first blank 121.

The inclined angle a between the first and second blanks 121,124 is preferably in the range of 5°-45°, more preferably 10°-30°, the second blank"bracing"the helical flyte against loads applied along the shaft of the screw pile anchor.

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