BACKGROUND
Drilling while driving is a known technique used when installing foundations to support single-axis solar trackers, fixed-tilt arrays, and other structures. This process consists of operating a drill rod and bit through a hollow foundation component, such as a screw anchor, while the component is driven into the ground; the drill may be independently operated through and slightly ahead of the driven component as needed, such as, for example, when rotation and downforce applied by the rotary driver fail to achieve the desired embedment depth. This requires a rotary driver and a separate drilling tool oriented along the same axis on the mast of the component driving machine. With this configuration, foundation components can be driven into a variety of different strata, up to, and including solid rock, without requiring a separate predrill step or without needing to mitigate a failed embedment. In such a system, the drill may be employed on an as-needed basis to assist with embedment, that is, only used when required. Ideally, the drill bit travels down at the same rate as the foundation component, just inside the lower end of it so that it is ready to extend if/when embedment of the foundation component stalls, that is, when additional downforce and torque fail to further embed the component. In such a case, the drilling tool may be automatically controlled to extend out of the lower end of the component and to begin hammering or drilling through the strata in front of it. An automated control system may be used to detect the stall condition and to automatically engage the drilling tool to extend out of the lower end of the foundation component to provide real-time drill assist, thereby creating a borehole to drive the component into.
In rock and in dry, hard soils, the rotation of the drill rod and bit combined with the emission of pressurized air from the impact end of the bit is sufficient to eject spoils so that the inside of the component remains clear of sand, rocks, and soil, whether the drilling tool is extended out of the component or not. However, when drilling through mud and clay, these soft materials may fill up the foundation component, encasing the drill bit and drill rod so that spoils cannot be ejected. When this happens, drill function is disrupted. Mitigation of this condition may require reversing the drill rod and cleaning out the center of the foundation component by hand, among other time-consuming mitigation steps. Therefore, it would be advantageous to have a foundation component compatible with drilling while driving that prevents the ingress of mud and clay when driving through these relatively soft materials while still allowing the drilling tool to engage when needed.
SUMMARY
In general, this disclosure relates to systems, devices, and methods for drilling foundation piles into various configurations of soil. Such processes may include operating a drill rod and bit through a hollow foundation component, such as a screw anchor, while the component is driven into the ground. The drill may be independently operated through and slightly ahead of the driven component as needed, such as, for example, when rotation and downforce applied by the rotary driver fail to achieve the desired embedment depth. This may require a rotary driver and a separate drilling tool oriented along the same axis on the mast of the component driving machine. In such embodiments, the foundation components can be driven into a variety of different strata, up to, and including solid rock, without requiring a separate predrill step or without needing to mitigate a failed embedment.
In such systems, the drill may be employed on an as-needed basis to assist with embedment. In certain such systems, the drill bit travels down at the same rate as the foundation component, just inside the lower end of the foundation component so that it is ready to extend if and/or when embedment of the foundation component stalls, such as when additional downforce and torque fail to further embed the component. In such embodiments, the drilling tool may be automatically controlled to extend out of the lower end of the component and to begin hammering or drilling through the strata in front of it. An automated control system may be used to detect the stall condition and to automatically engage the drilling tool to extend out of the lower end of the foundation component to provide real-time drill assist, thereby creating a borehole to drive the component into.
Disclosed is a foundation component having an elongated open shaft, an external thread form beginning at a first end and extending along the shaft, a driving coupler at a second end, opposite to the first end, and a cone received by the first end and extending from the first end. The cone is of a material having a lower elastic modulus than the elongated open shaft.
In some embodiments, the cone is consumable.
In some embodiments, the elongated open shaft is configured to receive a drilling tool therewithin.
In some embodiments, the driving coupler further comprises a ring includes a plurality of driving teeth.
In some embodiments, the plurality of driving teeth are configured to engage with a chuck of a rotary driver.
In some embodiments, the cone includes a conical tip and a male insertion portion opposite the conical tip.
In some embodiments, the male insertion portion is configured to be press fit into the elongated open shaft at the first end.
In some embodiments, the cone has a modulus of elasticity substantially lower than that of the elongated open shaft.
Also disclosed is a system having a rotary driver, an open-ended screw anchor foundation component, a driving coupler at one end of the foundation component, a drilling tool with an attached drilling rod extending through the rotary driver and into the foundation component, and a consumable cone received by and extending from an end of the open-ended foundation component. The consumable cone is a made from a material having a lower material strength than the screw anchor foundation component.
In some such embodiments, the drilling tool includes an upper portion and a lower portion and a drilling head on a distal end of the lower portion.
In some embodiments, the upper portion is configured to compress into the lower portion when the drilling head encounters resistance.
In some embodiments, the drilling rod includes a center channel configured to guide pressurized air through the drilling head. In this way the drilling spoils are urged upwardly around the open-ended screw anchor foundation component around the drilling head.
Also disclosed is a method of embedding a foundation component in mixed strata soil including inserting a consumable cone tip into a first end of the foundation component, driving the first end of the foundation component into the soil from an opposing second end with a rotary driver. While driving the foundation component, a drill rod and bit is operated within the foundation component without contacting the cone. If continued rotation and downforce applied through the rotary driver fails to result in additional embedment, the drill rod and bit are extended through the consumable cone and operating the drill rod and bit ahead of the first end while continuing to drive the foundation component.
In some embodiments, the inserting a consumable cone tip step is accomplished by press fitting the consumable cone tip into the first end of the foundation component.
In some embodiments, the driving the first end of the foundation component step is accomplished by attaching a drill chuck to a driving coupler coupled to a second end of the foundation component and rotating the drill chuck such that the foundation component is driven into the mixed strata soil.
In some embodiments, the drill chuck is attached to a ring of the driving coupler having a plurality of driving teeth.
In some embodiments, the method includes the step of guiding pressurized air through the drilling head such that drilling spoils are urged upwardly around the foundation component around the bit.
Also disclosed is a hybrid screw pile for drilling while driving in mixed density soils having a tip portion made of a first material, a shaft portion made of a second material. The shaft includes a section of hollow tube with an external thread form beginning proximate to the tip portion and a driving portion, opposite to the tip portion, for engaging with a rotary driver and for interconnecting to an upper foundation component. The first material has substantially lower modulus of elasticity than the second material.
In some embodiments, the tip portion is consumable.
In some embodiments, the shaft portion is configured to receive a drilling tool therewithin.
In some embodiments, the driving portion further comprises a ring comprising a plurality of driving teeth.
In some embodiments, the plurality of driving teeth are configured to engage with a chuck of a rotary driver.
In some embodiments, the cone further comprises a conical tip and a male insertion portion opposite the conical tip.
The details of one or more examples of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a perspective exploded view of a foundation system according to an embodiment of the present disclosure.
FIG. 1B is a perspective assembled view according to another embodiment of the present disclosure.
FIG. 2 is a partial cutaway view showing a drilling rod and drilling bit according to an embodiment of the present disclosure.
FIG. 3 is a figure of an exemplary soil strata according to an embodiment of the present disclosure.
FIG. 4 is a flow chart detailing the steps for embedding a screw anchor with consumable tip according to an embodiment of the present disclosure.
FIG. 5 is a side view of a portion of a mast of an exemplary screw anchor driving and truss assembly machine according to an embodiment of the present disclosure.
FIG. 6A is a side view of a consumable tip according to an embodiment of the present disclosure.
FIG. 6B is a top view of a consumable tip according to an embodiment of the present disclosure.
FIG. 7A is a side cross-sectional view of a consumable tip according to another embodiment of the present disclosure.
FIG. 7B is a side cross-sectional view of a consumable tip according to yet another embodiment of the present disclosure.
FIG. 8 is a block diagram showing an exemplary control system for the mast of the screw anchor installation and truss assembly machine according to an embodiment of the present disclosure.
DETAILED DESCRIPTION
The following description is intended to convey a thorough understanding of the embodiments described by providing a number of specific embodiments and details involving drilling while driving foundation components to support solar trackers, single-axis solar arrays and other structures. It should be appreciated, however, that the present invention is not limited to these specific embodiments and details, which are exemplary only. It is further understood that one possessing ordinary skill in the art in light of known systems and methods, would appreciate the use of the invention for its intended purposes and benefits in any number of alternative embodiments, depending upon specific design and other needs.
FIGS. 1A/1B show foundation system 5 for use in mixed soils with a drilling and driving machine according to various exemplary embodiments. It should be appreciated that in soils known to be firm or absent clay and mud, foundation system 5 may not be as advantageous or necessary. The base component of system 5 shown in FIGS. 1A/1B is screw anchor 10. Screw anchor 10 is a hollow, elongated metal component with a shaft portion 11, external thread form 14 and lower end 12 and driving coupler 20 at upper end 13. In some embodiments, it may be made from galvanized steel. In other embodiments, it may be made from so-called black steel or steel that has been weathered rather than hot dipped galvanized. In various embodiments, thread form 14 may start near the distal end of lower end 12. Driving coupler 20 may be a separate cast piece welded onto upper end 13 of shaft 11 or may be formed into it. Coupler 20 may include a ring of driving teeth 22 that are engaged by the chuck of a rotary driver on the installation tool, as well as connecting portion 24. Connecting portion 24, as shown, consists of a tubular projection having a generally curved (oblate spheroid) profile with a series of spaced-apart indented rings circumscribing its outer surface. When an upper leg or other foundation leg component is joined to the screw anchor, these indented rings may provide voids to deform the component into when crimping it to the screw anchor. The curved profile of connecting portion 24 may enable these components to pivot about the connecting portion 24 while resting on ring 22.
Also shown in FIG. 1A are alternative conical tips 30 and 40 that may be inserted into lower end 12 of screw anchor 10 before driving or, in some cases, before attaching the anchor to the chuck of a rotary driver, such as rotary driver 120 shown in FIG. 5. Starting with tip 30, as shown the conical tip may be formed from a material such as concrete having much lower modulus of elasticity than either screw anchor 10 or the drill bit used to provide drill assist. As shown, male insert portion 34 has an outside diameter that is slightly narrower than the inside diameter of shaft portion 11 of screw anchor 10. This portion may be solid, as shown, or may be hollow. This enables tip 30 to be pressed into the open lower end 12 of the anchor until ledge 33 rests against the lower end 12. Once joined, only conical tip 32 will be visible. It should be appreciated that a different material than concrete may be used to make tip 30. To that end, tip 40 also shown in FIG. 1 is made from wood, particle board or a combination of wood and glue. Insert portion 44 of this tip has a cross pattern cut into to enable it to be compressed so that it fits more easily into open lower end 12. Ledge 43 limits the depth of penetration while tip portion 42 will lead the way down as the screw anchor is embedded.
In either case, that is, tip 30 or tip 40, whether made of concrete, wood, or other suitable material in various preferred embodiments, it will be made of a material having a modulus of elasticity substantially lower than steel (10-30 GPa versus 100-200 GPa for steel), the tip should be able to withstand normal driving pressure through mud and soft clay yet be breakable by the drill bit. When the tip hits rock or hard substrate, it may start to deform and break before embedment stalls. Then, when the stall condition is detected, the automated controller may actuate the drilling tool to extend out of the screw anchor and hammer through the tip and into the rock to clear a bore for the screw anchor to be driven into.
FIG. 2 shows an exemplary screw anchor with consumable tip according to various exemplary embodiments with the drilling rod and drill bit concealed within, such as just before or during a screw anchor embedment operation. Drill bit 80, as shown, consists of upper body portion 82 and lower body portion 84. Upper body portion 82 has a series of channels machined into its exterior to provide a path for drilling spoils to travel up and past the lower end of the bit. Lower portion 84 includes drilling head 85 which, as shown, has a series of carbide buttons that are used to pulverize rock. Lower portion 84 also has a pair of wings 86 that extend out when the bit encounters resistance so that upper portion compresses into lower portion. Wings 86 also have carbide buttons embedded in them. Plunging of the upper portion 82 into the lower portion 84 causes wings 86 to extend outward, allowing for an undercut to made into the rock or hard soil that creates a borehole wider than the inside diameter of the shaft 11. This enables the screw anchor 10 to be securely embedded. Because the tips are made of a softer material than the drill bit, the drill bit can easily break through whatever portion remains after the screw anchor stalls against rock or very dense soil. In some embodiments, pressurized air travels through center channel 113 in drill rod 112 and is ejected through drilling head 85 to push drilling spoils up the shaft 11 around drill bit 80. If cone 30 were not present, the inside of shaft 11 may become filled with mud and clay. Then, when the drill is needed, that is when embedment stalls, air would be prevented from pushing the drilling spoils up and past the drill bit. This, in turn, will impair the machine's ability to drill and may require time-consuming mitigation to clear.
FIG. 3 shows a soil strata in which the various embodiments of the invention may be most useful. The first layer shown in FIG. 3 is topsoil. Typically, the rotary driver will drive through this layer with little to no resistance. Below that, is a layer of soft clay and/or mud. Although clay is dense and heavy, it also highly malleable, can be quite wet, and in the absence of a closed tip would tend to flow into the screw anchor as its being embedded, surrounding the drill bit, and potentially filling up the center of the screw anchor shaft. This clay layer may last for several feet depending on local geology and water content. Although the drill is not required to embed through the topsoil nor the clay layer, to realize the full advantage of drilling while driving as well as automated embedment control, the drill bit needs to be always present while driving the foundation component so that it is ready to instantaneously deploy when needed to complete the embedment operation. In most cases, the rotary driver alone cannot embed the lower end of the screw anchor into solid rock layer without the drilling tool. By having the drilling tool available mere inches away from where it needs to be, the embedment operation is continuous and much faster than if it must be stopped so that a separate drilling tool could be used to create a borehole through the rock.
Turning now to FIG. 4, this figure shows a flow chart detailing steps of an automated method for embedding a screw anchor with consumable tip using an automated screw anchor driving and truss assembly machine according to various exemplary embodiments of the invention. The method starts in step 50 by loading a screw anchor with a consumable tip on to the rotary driver of the machine. This may consist of simply inserting the upper end with the driving coupler as shown in FIG. 1 up into the chuck of the machine where it is held in place. Then, by selecting start on the machine or on a remote control communicatively coupled to the machine, the embedment operation commences. This will cause the rotary driver to begin rotating the screw anchor while a drive chain pulls down on the assembly the rotary driver is attached to so that it moves down the mast and imparts torque and downforce to the screw anchor in specified amounts. At the same time, the drilling tool is activated to begin rotating the drill rod and to extend it down through the rotary driver into the screw anchor just above the consumable tip. While the embedment operation continues, a controller may monitor the output of one or more linear encoders, hydraulic pressure, or data from other sensors to determine if the embedment operation has stalled. A stall may be indicated when continued application of torque and downforce fails to result in additional embedment. If no stall is occurring, embedment may continue via the rotary driver. Otherwise, if in step 52 it is determined that stall has occurred operation may proceed to step 54 where the controller causes the rotary driver to pause. In various embodiments it may be desirable to reverse the rotary driver causing the screw anchor to come out some distance. The reason for this is so that the wings on the drill bit deploy when the bit exits the screw anchor. This will enable it to clear out the cone as well as the obstruction causing the stall. The drill rod may also be withdrawn to match the reverse progress of the screw anchor. Then, in step 55, the drilling tool is activated to pass through the lower end of the screw anchor, busting through the consumable tip. Once, the wings have cleared the open end, hammering of the drilling tool may begin to excavate a borehole in the rock or hard soil ahead of the screw anchor. At or near the same time, in step 56, the rotary driver may be re-actuated to resume the embedment operation. If the cone has held up while being driven through the relatively soft soil layer, the drill bit should be free of mud and clay and should function normally.
Turning now to FIG. 5, this figure shows a portion of a mast of an exemplary screw anchor driving and truss assembly machine usable with the various embodiments of the invention. Such a machine is currently manufactured and sold or leased by the applicant of this invention, OJJO, Inc. of San Rafael, CA under the trade name TRUSS DRIVER. As shown, machine mast 100 includes two movable assemblies 115 and 125 that support the drilling tool 110 and rotary driver 120 respectively. In some cases, assemblies 115 and 125 are attached to a common drive chain motivated by a motor located near the base of mast 100. The motor and drive train provide down force to the drilling tool 110 and rotary driver 120. In other cases, the drilling tool may also have its own motor enabling it to decouple from the rotary driver and move independently, that is, at a different rate of speed and even in a different direction along the shared drive chain. During a driving operation, screw anchor 10 is attached to the chuck of rotary driver 120. A controller then causes mast controls (pitch, roll, yaw, X, Y and Z) to orient the mast to the correct driving vector so that the driven screw anchor will point at the desired work point for that foundation. The work point is the point of intersection in free space of an imaginary line through the center of each pair of adjacent screw anchors. Then, the controller causes the rotary driver and drive chain motor to impart torque and downforce to the head of the screw anchor to drive it into the ground. At the same time, the drilling tool is activated to move down the mast so that the drill bit and rod extend through the rotary driver and screw anchor until stopping just above the consumable cone tip in the lower end of the screw anchor. The controller will continue to monitor the drilling operation to determine if the driving operation and stalls, and if so, to actuate the drilling tool to extend out of the lower end of the screw anchor, bursting through the cone and to begin hammering through the stall. It should be appreciated that the machine the screw anchor is attached to has been intentionally omitted as have other mast components not critical to the operation of the invention. In various embodiments, the controller may be housed in a control cabinet on the machine and communicatively coupled to the mast and to various sensors and controllable nodes on the mast as discussed in greater detail in the context of FIG. 8.
FIGS. 6A, 6B, 7A and 7B show various other consumable cone tip designs according to various other exemplary embodiments of the invention. For example, starting with 6A and 6B, tip 50 fits over the open end of screw anchor 10. As shown, it has a circular opening 54 that receives the lower end of anchor 10. In various embodiments, this simply pressed on by hand and held with a friction fit. In other embodiments, it may be tapped on with a hammer or other blunt instrument or may be glued in place prior to deployment at the job site. FIG. 6B top view looking down into tip 50. FIGS. 7A and 7B show hollow tips 60/70 respectively that also fit over the lower end of screw anchor 10. Tip 60 has channel 63 with walls 64 at its upper end that fit around the outside and inside of the lower end of anchor 10 providing a more secure fitment with cone portion 62. Tip 70 simply has a flange 74 and ledge 73 that hold tip 70 onto the lower end of anchor 10. The space inside tip portions 72 and 62 in these embodiments are open making it relatively easy for the drill bit to burst through. It should be appreciated that although in a preferred embodiment, the consumable tip is a smooth, cone-shaped tip, other quasi-pointed deflecting shapes may be possible as well.
FIG. 8 is a block diagram showing an exemplary control system for the mast of the screw anchor installation and truss assembly machine usable with the various embodiments of the invention. The system shown in FIG. 8 is controlled by a controller. In various embodiments, the controller may be a programmable logic controller (PLC) such as one manufactured by Schneider (Modicon), Allen-Bradley (Rockwell), Siemens (Simatec), Mitsubishi (Melsec) or other suitable manufacturer. The controller may also be a general purpose or special purpose microprocessor and may have integrated memory, storage, communications, and/or a power supply. As shown in FIG. 8, the controller and other system components are connected to a power bus and data bus. The data bus could be wired, wireless or a combination of these two and should not be construed as limiting on the various embodiments of the invention. On the left side of the diagram are various sensors located on the mast and/or the machine supporting it. These may include sensors such as hydraulic pressure sensors, inclinometers, global positioning system components providing location information in a coordinate system, rotary encoders, linear encoders, accelerometers, etc. These sensors (1-N where N is an integer) provide real-time information to the controller indicative of readings occurring before and during a screw anchor driving operation. The control nodes represent components of the mast and machine that are controllable. These nodes (1-X where X is a different integer than N) may include components such as the hydraulic pump, air compressor, mast mechanics that control the attitude and orientation of the mast, rotary driver, lower crowd motor controlling drive chain, drilling tool, upper crowd motor separately controlling the movement of the drilling tool along the drive chain, centralizer at the base of the mast, etc. The controller uses sensor data to control the various control nodes to orient the mast to the correct driving vector and to perform automated driving operations with on-demand drill assist. The sensors and controller provide closed-loop feedback control. It should be appreciated that the components shown in FIG. 8 need not be housed in the same enclosure and may be distributed at various points around the machine and mast. Details of the machine have been intentionally excluded, however, in some cases, the machine may be a tracked chassis with a diesel motor and hydraulic propulsion system similar to commercial drilling rigs and other pieces of heavy equipment.
It should be appreciated that the embodiments described and claimed herein are exemplary only. Those of ordinary skill in the art will appreciate modifications and substitutions that retain the spirit and scope of the invention.
Patent Application
20250223772
