NZ590391A - A sub-surface underwater anchor in two parts having a removable helical screw attached to a body - Google Patents

Abstract

An anchor assembly (200) for subsurface installation in a ground surface with a modular screw is disclosed. The anchor had a tubular body (201) having a helical element (203). A separate anchoring element (207) has a complementary helical element which engages with the helical element (203) on the body (201) to for the anchor assembly (200). (62) Divided Out of 585545

Description

Patents Form No. 5 THE PATENTS ACT 1953 COMPLETE SPECIFICATION Anchor We, Donna Ann Baker . 43 Moana View Road, Waikawa, Picton, New Zealand; Michael Arthur Keith Baker . 43 Moana View Road, Waikawa, Picton, New Zealand; and New Zealand Trustee Services Limited, of Unit 1, 142 Ferry Road, Christchurch, New Zealand, hereby declare this invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: FIELD OF THE INVENTION This invention relates to an anchor for subsurface installation in a ground surface. In an embodiment, the invention relates to an anchor for subsurface installation in an underwater environment. In an alternative embodiment, the invention relates to an anchor for subsurface installation on land.

BACKGROUND It is well known to use anchors to attach other objects to the ground. For example, anchors are used to attach boats or buoys floating on the sea surface to the seabed via a line. Anchors can be temporary anchors, for use when the boat or buoy is intended to be temporarily secured . Alternatively, anchors 10 can be permanent anchors, for use when the boat or buoy is intended to be permanently secured.

One type of permanent anchor is a drag or gravity anchor. The anchor is typically a large concrete block that is secured relative to the seabed by its sheer weight. A buoy or boat is attached to the block via a line. Drag anchors require a large amount of surface area to function correctly. The buoy and anchor are spaced apart from each other in a horizontal direction and the line will extend between the buoy and the anchor in a generally catenary shape. In normal conditions, the horizontal distance is about three times the sea depth. When a drag anchor is used to anchor a buoy in a marine farm, the horizontal distance required between the anchor and the buoy reduces the usable surface area of the farm.

Concrete block anchors are not suitable for anchoring to steep or sloping sea beds because they tend to move down the slope. Another problem with drag anchors is that they may move on the seabed during storms or rough seas.

Another type of permanent anchor is a screw anchor. Screw anchors have an anchor body with a helical member. The screw anchor is screwed into the sea bed by divers or remote controlled system using a drilling tool. Screw anchors require less horizontal space than gravity anchors. For example, it is possible to use a screw anchor and have horizontal distance about 1.2 times the sea depth. 2 Screw anchors reduce the environmental impact to the seabed compared to gravity anchors that can drag across the seabed. However, when installed in the seabed, the shaft of known screw anchors protrudes out from the seabed, which can have adverse environmental affects.

Conventionally, screw anchors are manufactured by separately forming each of the parts of the anchor and then welding them together to form the anchor. For example, an anchor is manufactured by welding a steel helical member to a steel tubular member. During the welding process, the helical member or tubular can become heat affected, which can weaken the anchor. The heat affected areas 10 are prone to breaking when the anchor is drilled into the ground. Additionally, the welding process can be expensive.

A helical member is conventionally formed by cutting a generally oval annular-shaped piece from a sheet of steel. The annular-shaped piece of steel is then stretched to form a helical member. When the 15 helical member is formed and then welded to the tubular member, it is common for the helical member to extend at an angle that is not 90° to the axis of the tubular member. Accordingly, when the anchor is drilled into the ground, voids can form in the surrounding ground above the helical member. Additionally, the ground above the helical member can become compressed.

When conventional screw anchors are used, the line is attached to the anchor prior to the anchor being inserted into the seabed. That increases the boat time required to assemble and install the screw anchors, which increases the cost to assemble and install the screw anchors.

It is an object of at least preferred embodiments of the present invention to provide an anchor 25 assembly that requires less time to assemble on site, and/or to at least provide the public with a useful alternative.

Additionally or alternatively, it is an object of at least preferred embodiments of the present invention to provide an anchor that will withstand typical loads applied to the anchor during insertion of the 30 anchor into the seabed, and/or to at least provide the public with a useful alternative. 3 SUMMARY OF THE INVENTION According to one aspect of the invention there is provided an anchor assembly for subsurface installation in a ground surface comprising: a tubular anchor body having a helical element; a separate anchoring element for engaging with a ground surface, the anchoring element having a helical ground engaging member; the helical element of the anchor body and the helical ground engaging member of the anchoring element being engageable to form an anchor.

Optionally the helical ground engaging member comprises a tapered helical ground engaging member having a radius that increases from a first insertion end towards an opposite end of the helical member.

Optionally the helical ground engaging member extends outwardly from the anchor about 90 degrees 15 relative to a longitudinal axis of the anchor body.

Optionally the separate anchoring element is substantially conical.

Optionally the anchor is suitable to be installed in an underwater environment.

Optionally the anchor assembly is suitable to be fully submerged in the ground surface.

The term "comprising" as used in this specification means "consisting at least in part of'; that is to say when interpreting statements in this specification which include "comprising", the 25 features prefaced by this term in each statement all need to be present but other features can also be present. Related terms such as "comprise" and "comprised" are to be interpreted in a similar manner.

This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, 30 and any or all combinations of any two or more said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

As used herein the term "(s)" following a noun means the plural and/or singular form of that noun. 4 As used herein the term "and/or" means "and" or "or", or where the context allows both.

The invention consists in the foregoing and also envisages constructions of which the following gives examples only.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described by way of example only and with reference to the accompanying drawings in which: Figure 1 is a front view of a first embodiment of the anchor; Figure 2 is a vertical cross-sectional view of the anchor of Figure 1; Figure 3 is an end view of the anchor of Figure 1, with the flange and helical member not shown for clarity; Figure 4 is a partial cross-sectional view of the anchor of Figure 3 taken through line B-B of Figure 3: Figure 5 is a front view of a swivel; Figure 6 is a bottom view of the swivel of Figure 5; Figure 7 is a partial vertical cross-sectional view of the anchor of Figure 1 together with a swivel, a drive head, and a drill string; Figure 8 is a perspective view of a retainer ring; Figure 9 is a bottom view of the drive head; Figure 10 is a cross-sectional view taken through fine C-C of Figure 9; Figure 11 is a cross-sectional view of the drive head engaged with the drive shaft of Figure 7 taken through line D-D of Figure 7; Figure 12 is a cross-sectional view of the drive head disengaged from the drive shaft of Figure 7 25 taken through line D-D of Figure 7; Figure 13 is a front view of an anchor body and anchor cone, prior to attachment; Figure 14 is a partial cross sectional view of the anchor body and cone of Figure 13, with the cone attached; Figure 15 is a front view of an anchor body and plate, prior to attachment; Figure 16 shows a number of separate plates that may be attached to the anchor body; and Figure 17 shows the first embodiment of the anchor installed in a ground surface.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Figures 1 to 4 show a first embodiment of an anchor 100. The anchor 100 is adapted to engage with a ground surface to secure the anchor in a ground surface. The anchor is used to attach other objects to the ground surface. The ground may be in an underwater environment, such as a seabed, river bed, or lake bed for example, as shown in Figure 17. Alternatively, the ground may include dry land. The ground may be substantially flat ground, a sloping, or substantially vertical surface. For example, the 5 anchor can be inserted into the seabed and attached to a boat, buoy or other object on the sea surface via a line 1. The line may be rope, cable, cord, catenaries, chain, or the like. When installed in the seabed, the anchor is fully submerged in the ground surface, as shown in Figure 17. Alternatively, a major portion of the anchor body may be buried in the ground surface so that only a minor part of the anchor body protrudes from the ground surface. Both alternatives are covered by the terminology 10 "subsurface installation".

The anchor 100 has an anchor body 101 and an anchoring clement, in the form of a helical member 103. The anchor body 101 is an elongate, substantially tubular component having an insertion end 105 and a line attachment end 107. The helical member 103 is positioned at or near the insertion end of 15 the anchor body and is integrally formed with the anchor body 101 The helical member 103 engages with a ground surface to secure the anchor 100 in the ground surface. In the embodiment shown, the helical member 103 is a tapered helical member in which the radius R of the tapered helical member 103 increases from a tip 109 of the helical member towards 20 the second end 111 of the helical member. The helical member 103 extends outwardly from the anchor body 101 at about 90 degrees relative to a longitudinal axis of the anchor body. By extending at about 90 degrees, when the anchor is inserted into the ground, the helical member will drill into the ground without working against itself or churning the ground as it is drilled into the ground. In addition, the anchor will not form voids above or below the helical member or compressing the 25 ground above or below the helical member.

With reference to Figures 5 and 6, the anchor assembly has a swivel 113 for attaching the line to the anchor. In the embodiment shown, the swivel has an eye 114 for receiving the line. The swivel is releasably engageable with the anchor body 101 at or near the attachment end 107 of the anchor body. 30 The swivel 113 is arranged to be engaged with the anchor body 101 by moving the swivel relative to the anchor in a first direction D1 transverse to the longitudinal direction of the anchor (see Figure 3) and then in a second direction D2 (see Figure 4) that is transverse to the first direction to an engagement position.

One of the anchor body 101 or the swivel has a shank with a tab extending at an angle from the shank. The other of the anchor body or the swivel has a complementary slot for receiving the shank and the 6 tab. In the embodiment shown, the swivel 113 has the shank 115 and the tab 117 and the anchor body 101 has the complementary slot 119. The tab is preferably disc shaped, as shown in Figure 6.

The slot 119 has a main 121 portion complementary to the shank of the swivel and a transverse 5 portion 123 complementary to the tab of the swivel. The transverse portion extends outwardly from the main portion in a first direction and a second opposite direction, as shown in Figure 4, corresponding to the shape of the tab. The swivel 113 is arranged to be engaged with the anchor body by moving the swivel relative to the anchor in the first direction D1 through the slot 121 and then in the second direction D2 that is transverse to the slot. In the embodiment shown, the second direction 10 is along the length of the longitudinal axis of the anchor. In the engagement position, the swivel is rotatable relative to the anchor body 101 when engaged with the anchor body.

Figure 7 is a cross-sectional view of the anchor and swivel in an engaged position, together with a drive head 125 and drill string 127. The anchor assembly also has a retainer for securing the swivel 15 113 relative to the anchor body 101 while simultaneously allowing rotational movement of the swivel relative to the anchor body. With reference to Figure 8, the retainer may comprise a split-ring 128 that is adapted to extend around the shank 115 of the swivel. The ring 128 prevents the swivel from being moved in towards the anchor (ie in a direction opposite to D2) and released from engagement from the anchor body. The swivel has a shoulder or ledge 130, which the split ring can sit substantially 20 flush against. That reduces the risk of the arcuate surface of the swivel causing wear to the ring, which may otherwise cause the ring to split and fail.

Alternatively, the retainer may comprise a substantially wedge shaped plug that is adapted to be inserted into the transverse portion 123 of the slot. The plug 131 prevents the swivel from being 25 inadvertently moved in towards the anchor (ie in a direction opposite to D2) and released from engagement from the anchor body 101. If a wedge plug is used, the anchor assembly may have an internal annular member with a ledge that the plug can sit against.

The anchor is inserted into the ground using the drill string 127 and a drive head 125. The anchor has 30 engagement features for engaging with complementary engagement features of the drive head. The engagement features comprise protrusions extending outwardly from the anchor body 101 near the attachment end of the anchor. In the embodiment shown, the engagement features comprise rectangular shaped teeth 129. The teeth extend radially outwards from the anchor body and are evenly spaced around the circumference of the anchor body. The engagement features are integrally formed 7 with the anchor body 101.

With reference to figures 10 to 12, the drive head 125 has complementary engagement 20 features. In the embodiment shown, the engagement features comprise generally rectangular shaped teeth 132. 5 The teeth 132 extend radially inwardly from the drive head 125 and are evenly spaced around an internal surface 133 the drive head. The engagement features are integrally formed with the drive head.

The drive head 125 has a plurality of slots 135 that are complementary to the anchor engagement 10 features that allow the attachment end of the anchor to be inserted into the drive head. Each of the slots has a narrow neck 137 that leads into a wider portion 139 of the slot. The neck 137 has a width that generally corresponds to the width of the anchor tooth 129. When the anchor is engaged with the drive head, the teeth of the anchor are received by part of the wider portion 139 of the slot.

With reference to figures 11 and 12, when each drive head tooth 132 is engaged with an anchor tooth 129 on one side, there is a free space 141 between the drive head tooth and the anchor tooth on the other side. That allows the drive head 125 to rotate in a first drilling direction D3 to insert the anchor into a ground surface and then disengage by rotating in an opposite direction D4 without rotating the anchor in the opposite direction.

When the drive head and the anchor are engaged, a shear pin 143 extends between the drive head and the anchor through an aperture 144. The shear pin is inserted to sit in the position shown in broken lines in Figure 11. The shear pin holds the drive head and anchor in engagement as they are moved through water and into the ground. During drilling, the shear pin does not have any load applied to it. 25 The shear pin breaks when a specific load is applied to the shear pin, for example, when the drive head is rotated in the direction D3.

With reference to Figure 7, the anchor has a flange 145 extending around the anchor body 101 and radially outwards from the anchor body. As the anchor is being drilled into the seabed, the drive head 30 and attachment end of the anchor will become submerged in the seabed until the anchor is substantially fully submerged in the seabed. The flange prevents or at least substantially inhibits matter entering between the engagement features of the anchor and the engagement features 129 of the drive head, when engaged. The flange 145 is integrally formed with the anchor body 101. The flange 145 has a tapered deflection surface 147 that extends at an acute angle relative to the anchor 35 body 101 and an abutment surface 149 for contacting a lead surface 151 of the drive head. The flange 8 and engagement features are arranged such that when the engagement features of the anchor are engaged with the engagement features of the drive head, matter is substantially inhibited from entering between the engagement features of the anchor and the engagement features of the drive head. The deflection surface 147 deflects matter that is expelled from the ground as the anchor is 5 drilled into the ground. The abutment surface contacts a lower surface of the drive head. The abutment surface and lower surface of the drive head interact to prevent or at least substantially inhibit matter entering between the engagement members.

The anchor is an integrally formed component in which the anchor body 101, helical member 103, 10 tapered flange 145, and engagement features 129 are integrally formed as one piece. Accordingly, the anchor does not have any areas that have been adversely heat affected by welding, which could weaken the anchor. By integrally forming the helical member 103 and the anchor body 101 as a single piece, the helical member 103 extends outwardly from the anchor body 101 at about 90 degrees relative to a longitudinal axis of the anchor body. By extending at about 90 degrees, when the anchor 15 is inserted into the ground, the helical member will drill into the ground without working against itself or churning the ground as it is drilled into the ground. Integrally forming the parts as one piece removes the costs involved with assembly, including welding costs.

By integrally forming the tapered flange 145 and engagement features 129 as a single piece, the 20 location and distance between those parts of the anchor can be defined more precisely that when those parts are manufactured and attached separately. The precise locations of those parts of the anchor help inhibit matter entering between the engagement members as the anchor is drilled into the ground.

Integrally forming the parts as one piece ensures that the anchor body 101, helical member 103, 25 tapered flange 145, and engagement features 129 are formed from the same material. There are no areas that are formed from different materials. When the parts are welded together, the welding material is typically a different material to the base material of the anchor, which can cause corrosion. By integrally forming the anchor body 101, helical member 103, tapered flange 145, and engagement features 129 as a single part, the risk of corrosion is reduced.

With reference to figures 13 and 14, in an embodiment of the anchor assembly, the anchoring feature for engaging with a ground surface comprises a separate component in the form of an anchor cone 200, which is releasablv attachable to an anchor body 201. The anchor body 201 comprises a tubular anchor body having a helical connector element 203 at an insertion end. The anchor cone 200 has a 9 ground engaging member, in the form of a helical member 207. The helical element of the anchor body and the helical ground engaging member of the anchoring element are engageable to form an anchor. The anchor cone and anchor body each have corresponding apertures 206 for receiving fasteners 208.

The body of the anchor cone is a substantially conical component and the helical member 207 is a corresponding tapered helical member. The cone and helical member are integrally formed. The radius R2 of the tapered helical member increases from a tip 209 of the helical member towards the other end 213 of the cone. The helical member 207 extends outwardly from the anchor body 101 10 at about 90 degrees relative to a longitudinal axis of the anchor body.

With reference to Figure 16, in an embodiment the anchor assembly has separate plates 301a—301e that are releasably attachable to the anchor body. The plates have a number of different diameters, shown in Figure 16. The plates and the anchor body have complementary apertures 303 for receiving 15 fasteners. The plate is mounted on the anchor in the direction of the arrows shown in Figure 15. The outer diameter of the plate will be chosen depending on the intended use of the anchor. For example, depending on the expected load that will be applied to the anchor and/or the expected hardness of the ground surface.

A method of assembling the anchor assembly will now be described. The line 1 is attached to the swivel 113 at an earlier, convenient time to reduce the amount of boat time required to assemble and insert the anchor. The swivel 113 is then attached to the anchor body 101 by moving the swivel relative to the anchor in the first direction D1 through the slot and then in the second direction D2 that is transverse to the slot so that the swivel is in an engagement position. In the 25 engagement position, a portion of the swivel shank 115 extends outwardly from the anchor body 101 and the lower portion 123 of the slot is open. The swivel 113 is secured in the engagement position by either placing the retainer ring 128 or the wedge 131 plug in position. If a ring is used, it is placed around the shank of the swivel that extends outwardly from the anchor body. If a wedge plug is used, it is inserted into the lower, open portion of the slot. The swivel is then prevented from being 30 inadvertently disengaged from the anchor body 101.

If a separate cone 200 is being used, it can be assembled to the anchor body 201 prior to installation, or at an earlier time. Additionally, if a separate plate is being used, it can also be assembled to the anchor prior to installation, or at an earlier time.

The attachment end 107 of the anchor is inserted into the drive head 125 so that the teeth 29 slide along the narrow portion of the slots 137 in the drive head. The anchor body 101 is rotated relative to the drive head to the engaged position in Figure 11. The shear pin 143 is inserted through the aperture 144. A shoulder 140, together with the shear pin 143, prevents the drive head 125 and anchor from being disengaged. The drive head and anchor are taken to an installation site. The drill string 127 and drive head 125 are operated to drill the anchor into the ground. Once installed, the drive head 125 is operated in a reverse direction D4, to break the shear pin 143 and disengage the teeth of the drive head 125 from the teeth 129 of the anchor.

The drive head 125 is moved to the position relative to the anchor shown in Figure 12. In that position, the teeth 132 are aligned with the narrow portion 137 of the slots. The drive head can then be pulled away from the anchor, leaving the anchor and swivel installed in the ground, as shown in Figure 17.

Each of the components is preferably formed from a material that will not cause, or will at least substantially inhibit, electrolysis or corrosion between the components. The anchor body 101 and swivel are preferably formed from the same material. Alternatively, the anchor body and swivel may be formed from different materials, but which substantially inhibit, electrolysis or corrosion between 20 the components.

The separate plate and cone are preferably also formed from the same materials as the anchor body and swivel. The separate plate and cone may also be formed from different materials, but which substantially inhibit, electrolysis or corrosion between the components.

In an embodiment, the anchor body, swivel, plate and cone are formed from stainless steel. Alternatively, the anchor body, swivel, plate or cone may be formed from other metallic materials. The parts of the anchor assembly may be galvanized or painted to substantially inhibit electrolysis or corrosion. In other alternatives, the anchor body, swivel, plate or cone may be formed from carbon 30 fiber or reinforced polymeric materials.

The retainer ring and retainer wedge plug are each preferably formed from a suitable inert material. The shear pin is also preferably formed from a suitable inert material. For example, each of those components may be formed from a polymeric material, such as nylon. Alternatively, each of those 11 components may be formed from any other suitable polymeric material such as polyvinyl chloride (PVC) or rubber, for example.

The anchor is lighter to transport than previously known anchors, which can reduce transportation 5 costs of the anchors and makes installation easier.

Preferred embodiments of the invention have been described by way of example only and modifications may be made thereto without departing from the scope of the invention.

For example, the swivel has been described as having a tab and the anchor body has been described as having a complementary slot. However, it will be appreciated that the anchor may have a tab and the swivel may have a complementary slot.

The helical member has been described as a single helical member. It will be appreciated that the 15 anchor may have a series of helical members.

The anchor has been described for subsurface installation in an underwater environment. However, it will be appreciated that the anchor may he used on the land, for example to attach or securing other objects to the land via a line. 12

Claims (6)

WHAT WE CLAIM IS:

1. An anchor assembly for subsurface installation in a ground surface comprising: a tubular anchor body having a helical element; 5 a separate anchoring element for engaging with a ground surface, the anchoring element having a helical ground engaging member; the helical element of the anchor body and the helical ground engaging member of the anchoring element being engageable to form an anchor. 10

2. An anchor assembly according to claim 2, wherein the helical ground engaging member comprises a tapered helical ground engaging member having a radius that increases from a first insertion end towards an opposite end of the helical member.

3. An anchor assembly according to claim 1 or 2, wherein the helical ground engaging member 15 extends outwardly from the anchor about 90 degrees relative to a longitudinal axis of the anchor body.

4. An anchor assembly according to any one of claims 1, 2 and 3, wherein the separate anchoring element is substantially conical. 20

5. An anchor assembly according to any one of the preceding claims, wherein the anchor is suitable to be installed in an underwater environment.

6. An anchor assembly according to any one of the preceding claims, wherein the anchor assembly is suitable to be fully submerged in the ground surface. 25 AJ Pietras & Co Attorney for the Applicants 13