Patent Application
20140259991
The present invention is directed to a ground anchor and to a method of driving a ground anchor into the ground. The invention is particularly directed to a ground anchor having a breakable tip to assist in driving the ground anchor into soils having different densities.
Ground anchors are commonly used to support various structures and for use by utilities for anchoring supports, utility poles, and the like. The anchors often have an elongated shaft with a square or round cross-section. A top end of the shaft has a drive connection for coupling to a rotating drive assembly. The bottom, ground engaging end has one or more helical outwardly extending load bearing plates fixed to a hub.
One examples of a screw anchor is disclosed in U.S. Pat. No. 4,334,392 to Dziedzic. This device is a modular screw anchor having an elongated rod with one or more specialized anchor members. The shaft also includes an obliquely oriented beveled earth penetrating lead to facilitate installation in rock soils. The anchor has a tubular, rod-receiving hub having a polygonal cross-section. An outwardly extending helical blade is fixed to the hub.
U.S. Pat. No. 5,408,788 to Hamilton et al. discloses a screw anchor having a hollow hub for receiving a wrench. A helical, load bearing element projects outwardly from the hub. An elongated, pointed spade extends from the end away from the hub. The spade has two diametrically opposed angular cutting margins on opposite sides of the hub.
One example of a prior device is disclosed in U.S. Pat. No. 4,617,692 to Bond et al. which discloses a drilling tip and expansion anchor for drilling a hole in a wall. The threaded shaft is rotated in a first direction to expand the anchor with a drill tip attached to the end of the shaft. The shaft is then rotated in the opposite direction to unscrew the shaft from the tip.
U.S. Pat. No. 4,750,571 to Geeting discloses a drilling apparatus having a disposable tip. A disposable cutting tip is attached to the auger section which is positioned within the ground screen. The tip is attached to the auger by a shear pin or bolt. The shear pin breaks when the auger is removed from the ground thereby leaving the drill tip in the ground.
U.S. Pat. No. 4,898,252 to Barr discloses a cutting tip for a rotary drill bit. The drill bit includes a wear surface attached to a plurality of plates forming the carrier for the cutting element. As the cutting edge wears, the plates break away to increase the clearance of the rear portion of the cutting edge and reducing the size of the wear surface to reduce the resistance to drilling.
U.S. Pat. No. 5,899,123 to Lukes discloses a threaded fastener having a drill point connected to the threaded fastener by a frangible line. The drill tip drills a hole through the work piece until the drill tip engages an inclined surface thereby causing the drill tip to break away from the threaded fastener.
U.S. Pat. No. 6,588,515 to Wentworth et al. discloses a rock drilling bit with a plurality of cutting teeth raked into the cut of the drilling bit. The teeth are angled at about 30° to provide the shear cutting force. The arrangement of the teeth reduces shock and vibration applied to the housing.
U.S. Pat. No. 7,182,556 to Takiguchi et al. discloses a drill with a disposable insert tip. The drill has a drill main body and an insert that is attached to the main body. The end of the main body has a plurality of guiding grooves shown in
U.S. Pat. No. 8,109,700 to Jordan et al. discloses a replaceable tip for a bit or auger. As shown in
While these prior devices have generally been suitable for their intended purpose, there is a continuing need in the industry for improved ground anchors.
The present invention is directed to a screw ground anchor and assembly for driving the ground anchor into the ground. The invention is particularly directed to a screw ground anchor having a breakable tip that breaks under stress while penetrating the ground to form a blunt angled tip adapted for penetrating dense soil and rock.
The ground anchor of the invention has a ground engaging end forming a pointed tip that is able to stabilize the anchor and to penetrate the ground by a drive assembly in softer soils. The ground engaging end with the pointed tip has angled faces that are able to penetrate the ground in various soil and rock conditions. The ground anchor also includes a hub with a helical load bearing screw for supporting a load and/or anchoring cables or other structures.
Accordingly, one aspect of the invention is to provide a ground anchor and screw that is able to penetrate the ground to support a load or anchor a structure where the ground anchor can be used in hard and soft soils without the need to replace the tip during use and installation when different soil and rock conditions exist.
The invention is also directed to a ground anchor that can be used with conventional driving apparatus without the need to modify the existing drive or drilling apparatus.
Another feature of the invention is to provide a ground anchor having a blade with a tip that can be used in softer soils at the surface and is also able to efficiently penetrate the harder subsoil without the need to replace the drilling tip or to remove the assembly from the ground to change the assembly or anchoring members.
The screw ground anchor assembly of the invention has a hub with a load bearing helical screw and a ground engaging end that is able to penetrate the ground to drive the load bearing screw into the ground to a depth necessary to support the desired load or anchor the intended structure.
The screw ground anchor of the invention has a blade extending axially from the assembly where the blade has side faces that converge to a pointed tip. The pointed tip can have a blunt, flat surface extending substantially perpendicular to a longitudinal axis of the anchor. The blade has two opposing major faces that converge toward the tip and two minor faces that also converge toward the tip. In one embodiment of the invention, the blade has a frangible end portion at the distal end that can break away under a predetermined torque and stress produced by the driving assembly as the blade penetrates the ground. The frangible end portion is able to provide an axial end face with a larger ground engaging surface area with an angled face that is able to penetrate harder soils and rock compared to the smaller pointed tip. The ground engaging axial surface formed by the frangible end portion has an angled face extending at an incline with respect to the longitudinal axis of the anchor.
The side faces of the blade can have a frangible portion formed therein that is able to break under the torque produced by the drive assembly and the resistance to the ground to expose and form the new ground engaging end. The frangible portion allows the end portion to break away when harder soils are contacted during the installation of the ground anchor without the need to remove the ground anchor from the ground or assembly from the ground when hard soils are encountered. The ground anchor is able to drill past and around the broken separated end so that it is not necessary to remove the broken end from the ground. The broken end of the ground anchor can be left in the ground along with the remaining debris.
At least one of the side faces of the blade can have a groove formed therein extending across the face to define the frangible portion and breakable end portion. In one embodiment, the blade has the two opposing major surfaces each formed with a groove to define a frangible line extending between the grooves that can break under a predetermined load or torque to expose a new surface for penetrating the ground, thereby enabling the ground anchor to continue penetrating the ground. In one embodiment, the groove extends transversely across the blade along a plane perpendicular to a center axis of the ground anchor. In another embodiment, the groove can extend across the blade along a line that is oriented diagonally with respect to the longitudinal axis of the ground anchor.
The ground anchor in another embodiment can have a serrated edge formed at the groove forming the frangible portion to expose serrated teeth when the breakable end portion separates from the blade.
These and other aspects of the invention are basically attained by providing a ground anchor comprising a shaft adapted for coupling to a drive assembly to rotate the ground anchor. A body portion is integrally formed with the shaft, The body has a dimension greater than the shaft. The body has a top side coupled to the shaft and a ground engaging bottom side. A blade projects downwardly from the bottom side of the body portion. The blade has first and second major faces converging to an axial face at a distal end of the blade from a first cutting edge. First and second minor faces extend between the major faces and converge toward the axial face at the distal end. The blade has a frangible portion for breaking an end portion of the blade from the ground anchor to form a second cutting edge.
The various features and advantages of the invention are also attained by providing a ground anchor adapted for driving into the ground. The ground anchor comprises a hub having a radially extending, helical load bearing member. The load bearing member extends outward from the hub and has a leading edge and a trailing edge. A body portion with a top side is coupled to a bottom end of the hub and a bottom side facing away from the hub in an axial direction with respect to the hub. A blade projects axially downward from the bottom side of the body portion. The blade has first and second major faces and first and second minor faces extending between the major faces. Each of the major and minor faces converge to a distal end having a first axial face. The blade has a frangible portion to break an end portion from the blade to expose a ground engaging second axial face having a dimension and surface area greater than the first axial face.
The objects and advantages of the invention are further attained by providing a method of anchoring a structure to the ground. The method comprises driving a ground anchor into the ground to a first depth. The ground anchor has a hub with a radially extending helical load bearing member. The load bearing member extends outward from the hub and has a leading edge and trailing edge. A body portion with a top side is coupled to a bottom end of the hub and an axially facing bottom side faces away from the hub. A blade projects from the bottom side of the body portion. The blade has first and second major faces and first and second minor faces extending between the major faces. Each of the major and minor faces converge to a distal end having a substantially blunt axial face with a first dimension. The method further comprises driving the ground anchor into the ground to a second depth whereby a breakable end portion of the blade breaks free of the tip to expose a second blunt axial face having a second dimension greater than the first dimension without removing the ground anchor or broken end portion from the ground. The structure is then coupled to the ground anchor.
The various objects, advantages and salient features of the invention will become apparent from the annexed drawings and detailed description of the invention which form part of the original disclosure.
The following is a brief description of the drawings, in which:
The present invention is directed to a screw ground anchor for penetrating the ground for anchoring or supporting a structure. As shown in
Referring to
The ground engaging lead 18 of the ground anchor 10 has a body portion 34 with a top face 36 and bottom face 38. The top face 36 of body portion 34 includes a shaft 40 extending axially in an upward direction. The shaft 40 has a substantially cylindrical shape with an axial bore 42 as shown in
A ground engaging blade 46 extends axially from the bottom face 38 of the body 34. As shown in the drawings, blade 46 has tapered sides that converge to an axial end face 48 at a distal end of the blade 46. Blade 46 has a first major face 50 and a second opposing major face 52 that converge toward the axial end 48 and a first minor face 54 and a second minor face 56 that converge to the axial end 48. The axial end face 48 typically has a flat surface lying in a plane perpendicular to the longitudinal axis of the anchor and blade for forming a cutting edge.
The body 34 has an enlarged area with an outwardly facing surface 58 extending axially downward from the hub 20. The bottom surface of the body 34 in the area of the enlarged portion forms an inclined surface 60 that extends from the first minor face to the second minor face as shown in
The blade 46 has a substantially trapezoidal shaped cross-section. The first major face 50 and second major face 52 are inclined with respect to each other and the first minor face 54 and second minor face 56 are inclined with respect to each other. The first and second minor faces are also formed at an incline with respect to the first and second major faces. The trapezoidal shaped blade forms a first cutting edge 62 formed between the first major face 50 and first minor face 54, and a second cutting edge 64 formed between the second major face 52 and the second minor face 56.
Referring to
In the embodiment shown, the axial end face 48 of the blade 46 has a substantially flat surface extending perpendicular to the center axis 70 to form a blunt end. As shown in
The groove 68 in the blade 46 forms a frangible break line 74 that causes the end portion 80 to break away from the blade 46 when the ground anchor contacts hard soil or rock. The end portion 80 breaks away to from an end face 82 that has a surface area larger than the axial end face 48 where the end face 82 is formed at an incline with respect to the center axis 70 as shown in
In a second embodiment of the invention shown in
In the embodiment shown, the ground engaging lead 92 includes a blade 98 having a first major face 100, and an opposing second major face 102. A first minor face 104 and second minor face 106 extend between the first major face 100 and the second major face 102 to define the blade 98 with a substantially trapezoidal shaped cross-section as in the previous embodiment. Each of the major faces 100 and 102 and each of the minor faces 104 and 106 converge to form a pointed axial end 108 to form a ground engaging tip. The axial end 108 has a substantially flat surface formed in a plane substantially perpendicular to the longitudinal axis 110 of the ground engaging anchor 90. As in the previous embodiment, the axial end 108 is off-center from the longitudinal axis 110 such that the axial end rotates in a circular path adjacent to or outside the longitudinal axis 110.
Referring to
The second major face 102 includes a second groove 124 that is axially spaced from the first groove 112 towards the axial end 108 and substantially parallel to the first groove 112. As shown in
During use, the ground anchor 90 is connected to a rotary drive assembly as in the previous embodiment and driven into the ground by the rotational driving force of the drive apparatus. The blunt axial end 108 initially penetrates the soil at the surface for driving the ground anchor 90 into the ground. As the ground anchor 90 is driven to greater depths, the stress on the breakable end portion 116 of the blade 98 causes the end portion 116 to break away from the upper portion 114 along the break line 118.
In the embodiment shown, the break line 118 typically extends substantially in the plane of the first upper face 120 to the inner edge of the first upper face 126 of the second groove 124 as shown in
As shown in
Another embodiment shown in
The upper edge 142 of the groove 68′ is formed with a serrated edge to define a plurality of teeth 146. As in the previous embodiment, the groove 68′ defines a break line 74′ extending diagonally across the blade 46′. As the ground anchor 140 is driven into the ground, the stress and torque applied to the end portion 80′ of the blade 46′ breaks along the break line 74′ to expose the teeth 146. As shown in
While various embodiments have been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention as defined in the appended claims.
