Abstract:
An single apparatus to drill and lift core specimens from an aggregate field includes a frame structure that can be deployed to a workface and is adapted to hydraulically deploy a rotating core drilling bit upon that workface to cut a core specimen from the substrate. The hydraulic deployment of the drill bit is self aligning and does not require complex alignment steps to ensure the maximum cutting efficiency and lifetime of the bit. The same apparatus that can be used to drive and deploy the drill bit can also be adapted to receive and lift the as-cut core specimen from the newly created hole in the substrate. Once lifted, the received specimen can be positioned out of the work area so that work within the newly created circular hole can progress.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable. 
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates generally to a device to drill hardened aggregate materials. More particularly, the invention relates to an apparatus to cut and pull generally cylindrical “core” sections out of an aggregate material substrate. More particularly still, the present invention relates to an apparatus to cut and pull generally cylindrical forms from steel reinforced concrete, leaving a generally cylindrical hole where a continuous pour of concrete once existed. 
     BACKGROUND OF THE INVENTION 
     Concrete is widely used as a building material in various types of construction projects because of its material advantages in the properties of hardness, durability and compressive strength. Concrete is considered to be in the class of “Aggregate” materials because it typically comprises an aggregation of limestone, sand, and other materials held together by a cement binder. The ability of concrete to withstand various environments enables it to be used in both subterranean and above-ground applications. Examples of subterranean use of concrete include building foundations, tunnels, and underground fluid, gas, and power transmission conduits. Above-ground uses of concrete can include structural walls, bridges, and roadways. Interestingly enough, many roadways and bridges use concrete for both above and below ground applications, often simultaneously withstanding the environments of water, extreme heat, and extreme cold. 
     Although concrete is highly resilient to compressive forces, it can be damaged easily if exposed to tensile or bending loads without reinforcement. Concrete strengthening is typically performed through the deployment of generally cylindrical steel reinforcement bars, commonly referred to in the construction industry as “re-bars.” Although reinforcement materials are available in a wide assortment of forms and composition, plain carbon steel re-bars are the most widely used because of their broad availability and low cost of manufacture. Typically, before a concrete form is to be poured, the re-bars are arranged within the form in a pattern and at a spacing determined by the design and geometry of the object to be poured. In the example of a flat “slab” of concrete, re-bars are usually laid out in a grid-like pattern at a depth often near the middle of the slab thickness. Once the re-bars are arranged, concrete is poured within the rest of the form and left to harden. The resulting material is known as a “composite” because two dissimilar materials are combined with one another to form a new composition with unique physical properties. 
     Concrete is used frequently because its initial liquid form is easy to deploy and is extremely durable and hard when cured. One major drawback to concrete is that it is very difficult to modify effectively once cured. Often, it is desired to have access to areas that may be covered by cured concrete, especially in regards to roadways or foundations. For example, if a project requires the repair or installation of sewer lines, it may be necessary to unearth or otherwise dismantle portions of streets and highways will need to be unearthed or otherwise dismantled to allow the work to continue. Traditionally, workers with heavy impact tools break up the surrounding area and then clear a path for the work to progress. Although effective, this method often affects an area of the workpiece that is much larger than required. Because a large area is “broken-up,” a repair operation must be performed to replace the concrete that was sacrificed in order to create the desired access way. Furthermore, the “break-up” method for modifying concrete installations is highly time consuming and is a destructive process. Concrete that is broken up to remove is not easily replaceable once the work is completed and typically requires a new pour of concrete to patch the area affected. 
     Recently, techniques such as concrete “coring” and “sawing” have come into light that greatly reduce the amount of the “affected” area surrounding a concrete worksite. Sawing typically involves the use of a large circular saw to saw completely through the thickness of the concrete and re-bar to cut out the desired area. The benefits of sawing are that precise cuts can be made thus enabling the affected area for polygonal shaped cutouts to be minimized. Once the cutout is sawed, a crane can be brought in to lift and remove the cutout as one solid piece. After the work is performed, the piece can be replaced by the crane and re-secured with sealant or concrete patching. The main advantage of concrete sawing of this type is that the affected work area is minimized. Additionally, the affected area can be quickly and inexpensively replaced and repaired following service to the exposed earth. 
     The primary drawback of the disc-sawing method is that it is limited to polygonal cutouts and therefore does not permit generally circular holes to be cut. For example, if a circular cutout for the installation of a pipe is desired, a larger polygonal (usually rectangular) cutout must be removed. Once the area is cutout, the pipe is installed in place and the annulus between the cutout and pipe must be re-poured and reinforced. Furthermore, whereas traditional “breaking” operations required only a few workers with jackhammers and material removal equipment, concrete sawing requires more costly cranes and sawing equipment to be maintained on site. Other examples of items that would require such circular cutouts include, but are not limited to, manholes, junction boxes, circular shaped utility stations, and conduit installations. 
     To make circular cutouts in aggregate materials, a process known as core drilling is often performed. Traditional core drilling applications include the delivery, assembly, installation, and alignment of a drill rig. The drill rig typically takes the form of a cantilevered frame structure that rotates a coring bit with a drive motor. Although they are typically much larger, coring bits closely resemble the “hole saws” used by carpenters as they generally take the form of cylindrical barrels with cutting teeth disposed about the circumference of one end of the barrel. The structure of a core drilling rig typically takes the form of a cantilevered frame that suspends and drives the bit from one side. 
     A significant drawback to a rig of this type is that it must undergo significant manual setup steps to ensure that the apparatus is properly leveled and the axis of the hole is normal to the plane of the workface. Proper alignment ensures that the cantilevered load is distributed substantially evenly across the cutting surfaces of the drill bit to maximize bit life. Whilst in operation, downward force is applied to the bit manually by an operator that operates a load handle from one side of the rig. The operator typically pulls the load handle in a downward direction to force the drill bit down, in a manner similar to the operation of a drill press. As the bit is rotated and loaded, the core drill cuts through both the aggregate material and any reinforcement materials that may be present. In concrete drilling, it is not uncommon for the bit to cut through several inches of concrete, followed by a few inches of composite concrete and steel, and finish through several more inches of concrete. This type of cutting condition places a severe amount of stress and wear upon the teeth of the drill bit, thus making proper setup and alignment paramount. 
     Because a typical core drilling apparatus must be manually aligned and leveled, it is often difficult to ensure that it begins and stays in proper alignment. An inherent flaw in the design of the traditional drilling rig is that the cantilevered construction allows the bit to “walk” or become further misaligned as bit penetration progresses downward. Once the bit walks out of alignment, the cutting teeth at the end of the bit are no longer as able to be as resilient to wear as they were at the beginning of the operation. As a result, it is not uncommon for cutting teeth of core drilling bits to require time consuming replacement and repair either during or following a drilling operation. The cutting performance and efficiency of a bit could be increased if the bet could be kept in alignment. If the bit walks, the time to cut core specimen will be increased. Furthermore the operation of the conventional drilling apparatus requires that a worker remain within close proximity to the machine throughout the drilling process to apply downward thrust. Finally, when core drilling is completed, the entire apparatus must be disassembled and removed from the work area so that a separate lifting crane, as deployed for sawing operations, can be brought in to remove the core specimen. This lifting crane further consumes valuable resources as it requires an operator to man it in addition to the capital and transportation costs required to deploy it at the job site. 
     For the purposes of worker safety, it would also be preferred for a drilling apparatus not to require the operator to be so close to the rotating machinery and for the operator to not have to continually manually bias the loading device. To reduce operation costs, it would be desirable to create a core drilling apparatus that could avoid the costs associated with a supplemental lifting crane and reduce the size of the operation and support crew. 
     The present invention addresses the shortcomings of the prior art. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention overcomes the deficiencies of the prior art by presenting an apparatus and method for drilling and lifting core specimens efficiently with a single machine. The preferred embodiment of the present invention includes a frame structure that can be deployed to a workface and is adapted to hydraulically deploy a rotating core drilling bit upon that workface to cut a core specimen from the substrate. The hydraulic deployment of the drill bit is self aligning and does not require complex alignment steps to ensure the maximum cutting efficiency and lifetime of the bit. 
     The same apparatus that can be used to drive and deploy the drill bit can also be adapted to receive and lift the as-cut core specimen from the newly created hole in the substrate. Once lifted, the apparatus includes wheels so that it and the received specimen can be positioned out of the work area so that work within the newly created circular hole can progress. Furthermore, the same apparatus that is used to drill and pull core specimens can easily be adapted to lift and pull saw cut slab sections for more traditional, non circular shaped aggregate section removal. When equipped with an aggregate saw, the apparatus of the present invention is capable of performing a wide array of aggregate cutting and sawing tasks on a single platform, thus requiring operating crews to carry less equipment to the job site. Using the machine and methodology of the preferred embodiment of the present invention, a work crew can carry out core drilling tasks faster and more efficiently than previously possible. 
     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more detailed description of the preferred embodiment of the present invention, reference will now be made to the accompanying drawings, wherein: 
     FIG. 1A is a front schematic view of a core drilling and lifting apparatus in accordance with a preferred embodiment of the present invention; 
     FIG. 1B is a side schematic view of the core drilling and lifting apparatus of FIG. 1A; 
     FIG. 2 is a schematic view of the core drilling and lifting apparatus of FIGS. 1A-B engaged in a drilling operation; 
     FIG. 3 is a schematic view of the core drilling and lifting apparatus of FIGS. 1A-B engaged in a lifting operation; and 
     FIG. 4 is a schematic view of the core drilling and lifting apparatus of FIGS. 1A-B engaged in lifting a saw-cut aggregate section. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to FIGS. 1A-B, a drilling and pulling apparatus in accordance with a preferred embodiment of the present invention is shown. Apparatus  100  is preferably constructed as a structural frame that is deployed over a workface  102  from which a generally cylindrical hole is to be cut. Apparatus  100  includes a platform  104  supported by a plurality of legs  106  (preferably 4) and surrounded by guard rails  108 . Platform  104  is constructed to withstand high loads in directions normal to workface  102  and is preferably manufactured as a welded steel frame with a plurality of braces  110 , 111  and cross members  112 . 
     Legs  106  are welded to cross members  112  and braces  110  of platform  102  and preferably include wheels or casters  114  at their distal end. It is preferred that two adjacent legs  106  of a four legged apparatus  100  have mechanically driven wheels  114 A, while the remaining two legs  106  include swivel casters  114 B. On legs  106  that are mechanically driven, guards  116  may be included to cover the wheel  114  if desired to keep dirt and debris away from the drive components. By combining mechanically driven wheels  114 A with swivel casters  114 B, apparatus  100  can be positioned into a desired location upon a workface  102  accurately with minimal effort and maximum speed. Mechanically driven wheels  114 A are preferably powered by an external hydraulic source (shown schematically as  144  in FIG. 2) although any suitable means of drive the wheels  114 A is acceptable as well. Hydraulic power is preferred to drive wheels  114 A as other components (as described below) preferably use hydraulics to function as a source of energy and a single hydraulic generator may be utilized to drive them at once. 
     Suspended underneath platform  104  is a drive assembly  120  adapted to rotate a drill bit  122 . Drive assembly  120  includes a drive frame  124  and is preferably suspended from the underside of platform  104  by an axial positioning cylinder  126 . Axial positioning cylinder  126  is mounted generally atop platform  104  and includes a load rod  128  that is allowed to pass through a bushing (not shown) and attach to the top of drive frame  124 . Axial positioning cylinder  126  provides the upward and downward force required to drill and pull cores from the workface  102 . Preferably, positioning cylinder  126  is hydraulically operated, but may be any other form of axial thruster including, but not limited to, pneumatic, ball screw, rack and pinion gear, and worm gear devices. 
     Housed within an opening of drive frame  124  is a drive motor  130 . Drive motor  130  is used to provide the angular thrust from drive assembly  120  to drill bit  122 . Drive motor  130  is preferably hydraulically driven but may be of any acceptable configuration including, but not limited to, electric, combustion engine, or pneumatic operation. Because an unsupported drive frame  124  is likely to rotate about load rod  128  of cylinder  126  when drive motor  130  is activated, two stabilization rods  132  are employed to counter this rotation. Stabilizer rods  132  are engaged through collars  134  atop platform  104  and are preferably secured to drive frame  124  by nuts  136 . Although more stabilizer rods  132  may be employed, two (as shown) are generally sufficient to restrict any angular “twist” of drive frame  124  to an acceptable level. 
     Drill bit  122  is preferably a saw-type drill bit and is suspended from drive frame  124  by an extension  138  and connected to drive motor  130  at its top. Saw-type drill bit  122  is preferably constructed from a cylindrical barrel  140  with a plurality of teeth  142  brazed about the circumference at its bottom end. The composition, number, and spacing of teeth  142  is a function of the type of material and desired cutting rate of workface  102 . Depending on material and desired rate of circumferential cut, different types, numbers, and spacing of cutter teeth  142  may be deployed about barrel  140  to maximize bit penetration speed and efficiency. Although apparatus  100  is shown employing a barrel-shaped saw bit  124  for drilling aggregate materials, it is to be understood that any other type of common drill may be employed, including but not limited to, twist bits, spade bits, masonry bits, and auger-type bits. In the circumstance whereby the material to be drilled is soil, gravel, or any other loose aggregate composition, an auger bit would be highly effective compared to a saw-type barrel bit shown in FIGS. 1A-B. 
     Referring now to FIG. 2, the operation of assembly  100  with drill bit  122  can be shown. To drill a core specimen, a hydraulic pump and distribution system  144  is attached to assembly  100  such that positioning cylinder  126 , wheels  114 A, and drive motor  130  all have access to the pressurized source. Using the distribution system controls to actuate and drive wheels  114 A, apparatus  100  is positioned over workface  102  until the center axis of drill bit  122  is aligned with the desired center of the core specimen to be cut. Because apparatus  100  is supported by four equal-length legs  106 , it is not necessary to manually level the apparatus as required by systems of the prior art. Once in alignment, wheels  114 A and  114 B are locked in position and drive motor  130  is activated. Once activated, drive motor  130  turns extension  138  and attached drill bit  122  in direction θ, preferably at a constant angular velocity. With bit  122  spinning in direction θ, axial cylinder  126  can be energized to drive the rotating bit  122  axially downward, in a direction P. 
     With bit  122  spinning and engaging workface  102 , teeth  142  at distal end of bit barrel  140  saw workface  102  material as bit  122  is further engaged downward. Often, the engagement of workface  102  will resist and slow down the rotation of bit  122 . To counter this resistance, operators can manipulate the hydraulic controls to increase the torque output of drive motor  130 . To provide this extra torque, it may be preferred that motor  130  be driven from a separate, more powerful hydraulic pump and distribution system, than wheels  114 A and cylinder  126 . This arrangement would be advantageous because it allows cylinder  126  to continue to function properly in the event that motor  130  requires more power than expected. If bit motor  130  were to draw so much power that cylinder  126  were to become inoperable, damage to bit  122  could result. To assist in the cooling and lubrication of bit  122 , an operator may spray a cutting fluid, preferably water, about the outer circumference of the bit barrel  140  with an ordinary garden hose (not shown). The fluid helps cool teeth  142  as well as carry cuttings away from the cutting surfaces. 
     Because cylinder  126  is used to apply load to rotating bit  122 , the cutting forces can be distributed evenly across the cutting faces of bit  122 . Maintaining uniform load upon bit  122  ensures maximum bit penetration rate into workface  102  and reduces wear on teeth  142  brazed about the circumference of bit barrel  140 . Systems of the prior art currently available do not apply even loads through the axis of their respective bits. Instead, these assemblies typically apply cantilevered loads from one side to the rotating bit. As noted above, an operator is required to stand alongside the rotating bit and use manual methods to apply the downward thrust. Cantilevered loading, as applied by prior art core drilling apparatuses, generally do not apply even thrust loads across the cutting surfaces of their bits. This uneven thrust limits bit penetration rates and shortens bit life, thus requiring the cutting teeth to be replaced more frequently. 
     Referring now to FIG. 3, drilling apparatus  100  is shown in a lifting configuration removing a core specimen  150  from workface  102 , thus exposing a hole  152 . Following drilling (as shown in FIG.  2 ), drill bit  122  and attachment extension  138  are removed from drive assembly  120  and set aside. With drill bit  122  removed, cylinder  126  can be lowered allowing for the attachment of a pulling rig  160 . Pulling rig  160  is attached to the underside of drive assembly  120  at locations  162  and  164  by engaging bolts or shear rods therethrough. Pulling rig  160  includes a load housing  166  and an anchor  168 . 
     Anchor  168  can be of any type or configuration commonly available as longs as it is secure enough to support the entire weight of core specimen  150  but is preferably driven into the center axis of core specimen  150  by commonly available impact tools. Furthermore, anchor  168  is configured to be attached to housing  166  at  170  by a bolt or shear rod (not shown). With pulling rig  160  attached to core specimen  150  in this manner, positioning cylinder  126  can be retracted, thus lifting core specimen  150  out of hole  152  away from workface  102  in direction Q. Once core specimen  150  is clear of hole  152 , drive wheels  114 A of apparatus  100  can be actuated to move the core specimen  150  to a desired deposit location. Once in position, position cylinder  126  can then be extended again enabling core specimen  150  to be deposited out of the way of workface  102  and hole  152 . The process can now be repeated, if necessary, by releasing pulling rig  160  and re-attaching bit  122  to drill another hole  152 . 
     A considerable advantage of a preferred embodiment of the present invention is its ability to both cut and lift the core-drilled specimen. Systems of the prior art only function to cut the core specimen. Once cut, the drilling apparatus must be removed so that a lifting rig may be brought on site to lift the core specimen from the workface to expose the newly cut hole. This approach, although effective, is more time consuming and costly than that provided by the present invention. The preferred embodiment of the present invention provides a means to both cut and remove the core specimen with one piece of equipment and with minimal manpower. 
     Because the apparatus  100  of a preferred embodiment of the present invention is desired to be deployed to a wide assortment of construction jobs, auxiliary equipment has been included to accommodate other types of work. Specifically, a slab lift system to lift large polygonal-shaped sections of aggregate material has been included upon platform  104  for convenience. Referring now to FIG. 4, slab lift system  200 , includes movable horizontal support beams  202  located between braces  110  and  111  at each end of apparatus  100 . Support beams  202  are slid into their preferred location atop beams  111  and include sliders  204  (shown in FIG. 1B) for supporting lift cylinders  206 . Cylinders  206  are configured with anchor retainers  208  at their bottom most end and are secured to sliders  204  upon beams  202  by piston rods  210 . 
     When a piece of cut aggregate material  212  is to be lifted out of place by system  200 , apparatus  100  is moved into position as described above by driving wheels  114 A and  114 B. Anchors  214  are then set within the slab  212  and are connected to retainers  208  of cylinders  206 . Cylinders  208  are moved into position by adjusting the locations of beams  202  and sliders  204  and are lined up with set anchors  214 . Once in position, cylinders  206  are pressurized to lower retainers  208  so they may be attached to anchors  214 . When anchors  214  are all properly attached, cylinders  206  are energized, thus lifting slab  212  out of workface  102  exposing a hole  216 . With slab  212  lifted, wheels  114 A and  114 B of apparatus  100  can be driven to relocate and deposit removed slab  212  elsewhere. When work is completed within exposed hole  216 , slab  212  can be returned and set back in place by reversing the steps above. 
     Advantages of the preferred embodiment of the present invention over systems of the prior art are numerous. Primarily, the present invention presents a system to accomplish both tasks of drilling and pulling cure specimens with a single machine. Furthermore, the device of the present invention is easily deployed and requires minimal setup time and resources. Because of its stability and even load distribution, the apparatus of the present invention is capable of drilling core specimens at a rate 2-3 times faster than conventional drilling systems. Additionally, because the system is preferably operated remotely by hydraulics, fewer operators are required and those that are required can maintain a safe distance from rotating equipment. Finally, an apparatus in accordance with the present invention offers the considerable advantage that a wide assortment of concrete cutting and lifting tasks can be performed by the same machine. In addition to drilling and pulling of core specimens, the apparatus is able to lift and deploy conventional equipment for sawing sections of concrete. 
     While a preferred embodiment of the invention has been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit of the invention.