AU784987B2

AU784987B2 - Screw anchor

Info

Publication number: AU784987B2
Application number: AU54447/01A
Authority: AU
Inventors: Frank Kriesl
Original assignee: KRIESL AND CO Pty Ltd
Current assignee: Kriesl & Co Pty Ltd
Priority date: 2000-10-06
Filing date: 2001-07-11
Publication date: 2006-08-17
Anticipated expiration: 2021-07-11
Also published as: AU5444701A

Description

Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

Name of Applicant: Actual Inventor(s): Address for Service: Invention Title: KRIESL CO. PTY. LTD.

FRANK KRIESL SANDERCOCK COWIE 69 Robinson Street, DANDENONG VIC 3175 SCREW ANCHOR r Details of Associated Provisional Application(s): No(s): Australian Provisional Application No. PR0574 Filed: 11h July, 2000.

The following statement is a full description of this invention, including the best method of performing it known to me/us: -1- 2001-07.1 IA.34l1krisel.lccomp .Apdl la- 0 TITLE: SCREW ANCHOR TECHNICAL FIELD OF THE INVENTION The present invention relates to screw anchors which are adapted to screw into the ground to provide an anchor against a tensile loading.

andercock Cowie 2001-07.1 I.AA339kies1comp~ctt.wPdI BACKGROUND ART Screw anchors have been in use for many years. These anchors include one or more helical flights mounted on a shaft, with the shaft co-axial with the axes of the helices.

Where there are more than one helical flight on the shaft, these helices are separated along the length of the shaft.

Traditional applications of screw anchors include providing tension anchors for the guy wires of electricity reticulation poles, radio masts, viticultural trellising and strainer posts.

For example, a type of screw anchor suitable as a tension anchor for tensioning viticultural trellising has a steel shaft with a length in the range of 1360mm to 2200mm, carrying one or more helical plates. Each helical plate is of about 150mm diameter and thick. The trailing end of the shaft carries an eye, which acts both as a coupling when screwing the anchor into the ground and as a mount for a guy wire.

These anchors are installed by screwing them into the ground with a post hole borer, from which the auger has been removed. The anchor is screwed into the ground at roughly 15-20° off vertical, leaning away from the trellis line.

When the eye at the trailing end of the anchor has reached ground level, the borer is disconnected. The eye is then pushed over, past the vertical line, towards the trellis, aimed into the direct line of pull of the guy wire. This results in the shaft of the anchor being bent into a 'dog's leg', with both the top helical flight and the bottom helical flight being displaced in opposite sideways directions away from the soil which has been disturbed by screwing the anchor into the ground. Both the top and bottom helical flights are then in relatively solid ground, improving the anchoring advantage.

It is however an aim of the present invention to provide improved screw anchors.

Sandercock Cowie 2001-07-11.A:339krio.lcompicte.wpd.2 SUMMARY OF THE INVENTION According to one form, the present invention accordingly provides a screw anchor which is suitable for insertion into the ground for anchoring against a tensile loading, the anchor including:a longitudinally extending shaft; and at least one plate which is shaped to substantially conform to the shape of a helical surface, wherein the axis of the helix is adjacent an edge of the plate, and wherein each plate is mounted on the shaft so that the axis of its helix is substantially co-axial with the axis of the shaft.

It is preferred that each plate be substantially circular when projected onto a plane which is normal to the axis of the helix.

When there are more than one plate mounted on the shaft, they are all of the same pitch and are mounted so that they all conform to the shape of one continuous helix.

When there are two plates mounted on the shaft, it is preferred that one of these plates be mounted near the leading end of the shaft and that the other plate be mounted substantially mid-way between the leading and trailing ends of the shaft.

It is preferred that the periphery of at least one plate carries teeth or over at least the portion of that periphery which is at the leading edge of the plate as it is screwed into the ground.

It is preferred that each tooth includes a surface which tapers outwardly in the direction of forward travel of the plate through the ground.

Sandercock Cowie 2001-07-.1 1.A:\339krclconpet.w.pd,3 which projects away from the leading surface in the direction of travel of the anchor as it advances into the ground.

According to a second form, the present invention provides a screw anchor which includes a shaft with two or more helical flights mounted one above the other on the shaft:with the leading edges of the flights in alignment; with the trailing edges of the flights in alignment; and with the tip that is defined by the intersection of the trailing edge and peripheral surface of one flight touching the tip that is defined by the intersection of the leading edge and peripheral surface of the adjacent flight.

It is preferred that the shaft passes substantially centrally through each flight.

It is preferred that the leading surface of at least one plate includes at least one tooth which projects away from the leading surface in the direction of travel of the anchor as it advances into the ground.

According to a third form, the present invention provides a screw anchor which includes a shaft with at least one helical flight mounted on the shaft wherein at least one helical flight includes:- Copyright. All rights reserved.

Sandercock Cowie 2001-07-.11.A:U39kris.cMplctwpd.4 a leading surface which faces substantially in the direction of travel of the anchor as it advances into the ground; and at least one tooth which projects away from the leading surface in the direction of travel of the anchor as it advances into the ground.

It is preferred that the at least one tooth is substantially triangular in shape with:one side of the triangle being contiguous with the helical flight; one side of the triangle forming a leading edge of the tooth in the rotational advance of the tooth through the ground; and one side of the triangle forming a trailing edge of the tooth in the rotational advance of the tooth through the ground.

It is preferred that the at least one tooth be formed by forming a substantially 'V-shaped' cut through the material of a flight, and folding the resulting 'V-shaped' tongue of material about the top of the in the direction of advance of the flight into the ground.

The clustered plates version suit soft soil. The offset versions provide more leverage in medium soil. A negative rake on the cutting edge of the flight allows displaced soil to slide to the outer edges of the flight.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a an elevational view, partly in section, of an installation utilising a screw anchor according to the first form of the present invention.

Figure 2 is a perspective view of a portion of a screw anchor according to the first form of the present invention.

Sandercock Cowie 2001-07.-11.A:39krisal.compC.wpd.S Figure 3 is a side elevational view of the portion of an anchor of Figure 2.

Figure 4 is a plan view of a plate for an anchor according to the first form of the present invention.

Figure 5 is a side elevational view of an anchor according to one embodiment of the first form of this invention.

Figure 6 is a plan view, partly in section, of the anchor of Figure o ooo *2 eee .ft Figure 7 is a plan view, partly in section, of an anchor according to a second embodiment of the first form of the present invention.

Figure 8 is a plan view, partly in section, of an anchor according to a third embodiment of the present invention.

Figure 9 is a plan view, partly in section, of an anchor according to another embodiment of the first form of the present invention.

Figure 10 is a detailed perspective view of a fragment of Figure 9.

Figure 11 is a perspective view of an embodiment of the second form of the present invention.

Figure 12 is an elevational view looking in the direction of arrow 12 of Figure 11.

Figure 13 is an elevational view looking in the direction of the arrow 13 of Figure 11.

Figure 14 is a perspective view of a portion of a screw anchor according to the third form of the present invention.

Figure 15 is a side elevational view of a portion of the anchor of Figure 14.

Sandercock Cowie 2001-07- .A:\3l9kricsl.compic.wpd.6 -7- Figure 16 is a plan view of a plate for an anchor according to the third form of the present invention.

Figure 17 is a plan of a flight blank showing the offset centre.

Figure 18 is a side view of an anchor with flights as shown in Figure 17.

Preferred embodiments of the invention are described with reference to the drawings.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE DRAWINGS Figure 1 shows a screw anchor 1 according to one form of the present invention being .used as a tension anchor for a wire trellis 2. The wires 5 of the trellis 2 are attached to a post 3 at an end of the trellis. The post 3 is in turn based sideways against tension in 15 the trellis wires 5 by tension in a guy wire 4. The guy wire 4 is in turn fixed through an eye 7 of the screw anchor 1.

As shown in Figure 1, the screw anchor 1 was initially screwed into the ground at the position which is shown by outline 6.

oooo The screw anchor 1 includes a shaft with an upper portion 8 and a lower portion 9. A plate is mounted on the shaft between the upper portion 8 and the lower portion 9.

Three plates which are indicated generally at 11 are mounted on the shaft 8, 10 near its leading end.

The shaft 8, 10 of the anchor at position 6 is screwed into the ground at roughly 1 5-20' off vertical, leaning away from the line of the trellis 1.

The eye 7 of the anchor was then pushed over, past the vertical line, towards the trellis 2. The eye 7 was pushed in the direction of the line of the trellis 2 until it is estimated that the upper portion 8 of the shaft into the direct line of pull of the guy wire 4. This Copyright. All rights reserved.

0 Sandercock Cowie 2006-03-23,Z 'Specificationskriesl cap wpd.7 -8results in the shaft of the anchor being bent into a 'dog's leg', with both the top helical flight and the bottom helical flight being displaced in opposite sideways directions away from the soil which has been disturbed by screwing the anchor into the ground. Both the top and bottom helical flights are then in relatively solid ground, improving the anchoring advantage.

It will also be appreciated that, when the screw anchor of the present invention is compared with the traditional tension screw anchor, the surfaces of the plates such as 9 and 11 are on average a greater distance from the shaft 8, 10. This greater average distance results in the plates 9, 11 having a greater length lever arm in resisting any further sideways bending in the direction of the line of the trellis 2.

As shown in more detail in Figures 2 and 3, the plate 9 conforms to a helical surface which has an axis which is co-axial with the shaft 8, 9 of the anchor 1. According to the 15 embodiment of Figures 1 to 3, each of the plates 11 adjacent the leading end of the anchor I is the same size and shape as is the plate 9. As shown in detail in Figures 2 to 4, the shaft 8, 9 of the screw anchor 1 passes through each plate 9 adjacent an edge of that plate.

20 Alternative preferred configurations of plates 9 on an anchor 1 are shown in Figures 5 to eeoc 8.

Figures 5 and 6 show a configuration in which the anchor 1 includes a group of four plates near the leading end of the anchor 1, and each successively displaced from adjacent plates by a distance of 900 about the shaft 10 of the lower portion of the anchor 1.

Figure 7 shows a configuration of two adjacent plates displaced from each other by 1800 about the shaft Figure 8 shows a configuration of three adjacent plates displaced from each other by 1200 about the shaft Copyright. All rights reserved.

SSandercock Cowie 2006-03-23Z:Spcificationskriesl cap wpd.8 Although Figures 5 to 8 illustrate plates 9 which are adjacent the leading end of the anchor 1, other preferred embodiments of the invention include such configurations of multiple plates 9 at other locations on the shaft of the anchor 1.

Figures 9 and 10 show especially preferred forms of the plates 9 according to the present invention. Figure 9 illustrates a preferred embodiment in which the periphery of each plate 9 carries teeth or scalloping 17 over at least the portion of that periphery which is at the leading edge 16 of the plate as it is screwed into the ground.

Each tooth 17 includes a surface 18 which tapers outwardly in the direction of forward travel of the plate 9 through the ground. The teeth 17 operate to displace soil outwardly from adjacent the leading edge 16 of each plate 9 as it travels through the ground.

Figures 11, 12 and 13 show a screw anchor according to another form of the invention.

According to the embodiment of these figures, a screw anchor which is indicated generally at 40 includes a shaft 36 which has three helical flights 31, 32 and 33 mounted one above the other on the shaft 36 with that shaft passing substantially centrally through each flight 31, 32 and 33.

Each of the flights 31, 32 and 33:passes around substantially 360° of the periphery of the shaft 36; is of substantially the same pitch; and are mounted with their leading edges vertically aligned and their trailing edges vertically aligned.

The flight 31 has a lower face 41 and an upper face 37. The flight 32 has a lower face 42 and an upper face 38. The flight 33 has a lower face 43 and an upper face 39.

The flights 31, 32 and 33 are mounted on the shaft 31 so that the tip that is defined by the intersection of the trailing edge and peripheral surface of the flight 31 is touching, or in Copyright. All rights reserved.

Sandercock Cowie 2006-03-23.Z:Spcifcations\kriel. cap. wp,9 close proximity to. the tip that is defined by the intersection of the leading edge and peripheral surface of the adjacent flight 32.

As can be seen from the elevational view of Figure 12, the leading and trailing edges of adjacent flights 31 and 32 define an open space 46 between them that is substantially triangular in cross section.

When the screw anchor 40 is advancing through the ground, soil that is displaced at the upper surface 37 of the flight 31 passes through the triangular area 46 and is then compressed by the lower surface 42 of the flight 32.

The same form of compression takes place at the transition region 47 between flights 32 and 33.

15 This compression serves to compact soil which has been disturbed by travel of the anchor into the ground.

Figures 14 to 16 illustrate a third form of the invention. According to this form of the invention, a helical plate 59 of a screw anchor includes teeth 60 and 61 which project away from the leading surface of the plate 59 and in the direction of advancement of the anchor as it is screwed into the ground.

It is preferred that teeth such as 60 and 61 be formed by punching a 'V-shaped' portion of the material of the plate 59 downwards from the plate in what will be its direction of advancement into the ground to form the substantially triangular teeth.

When the anchor is being installed into the ground, by clockwise rotation about the shaft 8, the edges 66 and 67 of the teeth 60 and 61 are the leading edges of the teeth so far as concerns rotational movement.

The teeth 60 and 61 break up the soil ahead of the plate 59, aiding in the advancement of the anchor into the ground.

SSandercock Cowie 2006-03-23,Z:SpeciftionskriesI cp. wpd.i0 -ll- Referring now to Figures 17 and 18, the shaft is 32mm diameter mild steel, Im long.

150mm diameter steel plate 68, 6mm thick is punched out of sheet stock and a sector like portion 70 excised in a press. The plate is pressed into a helical flight with a pitch of 450 and welded to the shaft 150mm from the sharpened entry end.

A second 150mm diameter, 6mm thick plate is centrally bored and pressed into the shape shown in Figure 3 and welded to the shaft 430mm from the sharpened end. The trailing end of the shaft is cold formed into an eye 72 and the entire anchor is galvanised by hot dipping. The anchor is inserted by removing the auger of a tractor-driven post hole borer and screwing the shaft into the ground. The guy wire is attached to the eye.

S

*SSS

Throughout this specification and in the claims which follow:the words 'comprising' and 'comprises' mean including, but not limited to, or 15 includes, without limitation; and any reference to a patent specification is not an admission that the contents of that specification are part of the common general knowledge of a person skilled in the art in Australia.

SSandercock Cowie 2006-03-23.Z:\Specifiations\kries cap wpd.I I

Claims

12- THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:- 1. A screw anchor suitable for insertion in the ground for anchoring against a tensile loading, the anchor including a longitudinal shaft, a helical flight at or near the leading end of the shaft and a like helical flight fixed substantially midway between the leading and trailing ends, wherein the helical flights are each made from a circular metal disc from which a substantially sector shaped portion is excised and the disc is twisted into a helical flight. 2. A screw anchor as claimed in Claim 1, wherein the shaft passes off centre through both flights. 3. A screw anchor as claimed in Claim 1 or 2, wherein the pitch of the flights is about 4. A screw anchor as claimed in any one of Claims 1-3, wherein the trailing end of the shaft has an eye to assist insertion. 5. A screw anchor with a pair of mutually spaced ground engaging parts substantially as herein described with reference to Figures 17 and 18. Dated this 2 4 t h day of May, 2006. SANDERCOCK COWIE PATENT ATTORNEYS FOR KRIESL CO. PTY. LTD. Copyright. All rights reserved. Sandercock Cowie

2006-05-25.Z:\Spccifiations\kriesI cap.wpd.12