Not Applicable.
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 xe2x80x9ccorexe2x80x9d 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.
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 xe2x80x9cAggregatexe2x80x9d 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 xe2x80x9cre-bars.xe2x80x9d 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 xe2x80x9cslabxe2x80x9d 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 xe2x80x9ccompositexe2x80x9d 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 xe2x80x9cbroken-up,xe2x80x9d a repair operation must be performed to replace the concrete that was sacrificed in order to create the desired access way. Furthermore, the xe2x80x9cbreak-upxe2x80x9d 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 xe2x80x9ccoringxe2x80x9d and xe2x80x9csawingxe2x80x9d have come into light that greatly reduce the amount of the xe2x80x9caffectedxe2x80x9d 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 xe2x80x9cbreakingxe2x80x9d 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 xe2x80x9chole sawsxe2x80x9d 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 xe2x80x9cwalkxe2x80x9d 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.
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.