| Drilling device and method for producing undercut holes -> Monitor Keywords |
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  Drilling device and method for producing undercut holesRelated Patent Categories: Boring Or Penetrating The Earth, ProcessesThe Patent Description & Claims data below is from USPTO Patent Application 20070193780. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO CO-PENDING APPLICATIONS [0001] This invention claims the benefit of German Patent Application No. 103 11 079.8 filed on Mar. 13, 2003, which is hereby incorporated by reference. FIELD OF THE INVENTION [0002] The invention relates to a drilling device and method of working concrete, brickwork, stone or the like by means of a drilling operation to produce undercut holes. BACKGROUND OF THE INVENTION [0003] The production of cylindrical drill holes in materials such as concrete, brickwork, stone and the like using various techniques generally referred to as "drilling" is common. Often during above-ground, below-ground and street construction, for example, accurately positioned drill holes are needed, for example, for inserting fastening elements. Provided the holes are simple "passage holes", the process is relatively simple, since there are no special requirements on the shape or geometry of the hole, apart from the nominal diameter. Dowel connections on the other hand impose additional requirements on the shape of the drilled hole. [0004] There are already a number of special methods of making so-called undercut holes for receiving heavy-duty dowel connections. The purpose of these methods is to improve the performance of the hole by shaping it so that the force needed to pull the fastening element out of the hole is increased. This applies in general, but in particular to cracked concrete. With cracked concrete, it is necessary to prevent the dowel connection from yielding or subsiding owing to the cracking, which would reduce the load-bearing capacity. A positive connection is clearly an advantage, particularly for filigree elements where there is a limit to the spreading-apart forces which can be absorbed by the component. [0005] Methods for making undercut holes, based, for example, on German Utility Model No 8808 256.3 and U.S. Pat. No. 4,993,894, first require the drilling of a standard drill hole with conventional drilling tools and machines. Then, in a second operation, by means of a geometrically not easily definable operation that is frequently called "swivelling or wobbling", the cylindrical drill hole is widened at its inner end so that the inner end of an inserted dowel connector can become "wedged" in the hole. This enables a relatively defined positive connection to be made with the dowel connector. [0006] Alternatively, there are special tools for making radial grooves in a standard drill hole and thus increasing its lateral roughness. These tools are used after drilling in a separate operation requiring a second working step. An example of such tools is disclosed in EP 0 795 677. [0007] U.S. Pat. No. 4,989,681 and German Utility Model No 297 15 261 disclose the asymmetrical insertion of cutting edges, on the assumption that the axial force (action of pressure) and the cutting angle will result in an easily reproducible undercut. [0008] In addition there are a number of devices on the market for working with movable, controlled cutting edges and blades. The difficulty usually is to remove the drilling dust on site and ensure unrestricted use under the rough conditions found at building sites. These methods and devices, hitherto in hand-guided versions, have not given satisfactory results with regard to the requirements of "widening" and "undercutting", and therefore have not been commercially successful. SUMMARY OF THE INVENTION [0009] In an embodiment, the invention provides a drilling device for producing undercut holes, said drilling device comprising a drilling tool having an axis of rotation and a cutting portion arranged such that it drills a hole with a longitudinal axis that is radially offset with respect to said axis of rotation and a centering device operable to apply a lateral force to said drilling tool for moving said axis of rotation towards said longitudinal axis to cause said cutting portion to form an undercut in a said hole. [0010] In another embodiment, the invention provides a method of producing an undercut hole comprising the steps of: drilling a hole with a drilling tool that has a cutting portion arranged to produce a hole having a longitudinal axis that is radially offset with respect to an axis of rotation of said drilling tool; and applying a lateral force to said drilling tool to cause said axis of rotation to move towards said longitudinal axis. [0011] In yet another embodiment, the invention provides a drilling device for producing undercut holes, said drilling device comprising: a drilling tool comprising a drill shaft that defines an axis of rotation of said drilling tool and a cutting portion carried at an end region of said shaft such that, in use, it drills a hole having a longitudinal axis that is radially offset with respect to said axis of rotation; and a centering device carried by said drilling tool, said centering device comprising an elongate member mounted so as to be slidable alongside said drill shaft into said hole to press against said drill shaft and apply a lateral force to said drill shaft, such that the axis of rotation is moved substantially into line with said longitudinal axis to cause said cutting portion to form an undercut in said hole, and at least one member connected with said elongate member by which a user of the driving device can move said elongate member alongside said drill shaft. [0012] In yet another embodiment, the invention provides a method of producing an undercut hole, said method comprising: drilling a hole with a drilling tool that comprises a drill shaft having an axis of rotation and a cutting head that is positioned such that said hole has a longitudinal axis that is radially offset with respect to said axis of rotation; maintaining rotation of said drilling tool with said cutting head at a predetermined location in said hole and sliding an elongate member into said hole alongside between said drill shaft and a wall defining said hole to apply a lateral force to said drill shaft and thereby move said drill shaft to bring said axis of rotation substantially into line with said longitudinal axis causing said cutting head to widen said hole at said predetermined location to form an undercut. [0013] In still another embodiment , the invention provides a drill device for producing undercut holes, said drilling device comprising: a drilling tool comprising a drill shaft that defines an axis of rotation of said drilling tool and a cutter carried at an end region of said drill shaft such that, in use, it drills a hole having a longitudinal axis that is radially offset with respect to said axis of rotation; and a centering device operable to apply a lateral force to said drilling tool for moving said axis of rotation towards said longitudinal axis to cause said cutter to form an undercut in a said hole, said centering device comprising: a centering member that is movable from a non-operative position outside of said hole to an operative position inside said hole in which the member is positioned between said drill shaft and a wall defining said hole so as to provide said lateral force; an operating device connected with said centering member by which an operator can move said centering member from said non-operative position to said operative position; a depth stop device by which a drilling depth of said hole is set; and a control device for said operating device, said control device being configured to prevent movement of said operating device by which said centering member is moved from said non-operative position to said operative position until said drilling tool has drilled said hole to said drilling depth set by said depth stop device. BRIEF DESCRIPTION OF THE DRAWINGS [0014] The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate the presently preferred embodiments of the invention, and together with the general description given above and the detailed description given below, serve to explain features of the invention. [0015] FIG. 1 shows a drilling tool of an embodiment of a drilling device according to the invention. [0016] FIG. 2 is an enlarged view of the drill head of the drilling tool of FIG. 1. [0017] FIG. 3 shows a drilling device according to a first embodiment of the invention incorporating the drilling tool of FIG. 1. [0018] FIG. 4 shows the drilling device of FIG. 3 in a different operating position. [0019] FIG. 5 is an enlargement of a portion of FIG. 3 showing the cutting portion of the drilling tool at the bottom of a drilled hole. Continue reading... Full patent description for Drilling device and method for producing undercut holes Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Drilling device and method for producing undercut holes patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Drilling device and method for producing undercut holes or other areas of interest. ### Previous Patent Application: Boring tool control using remote locator Next Patent Application: Methods and apparatus for drilling open hole Industry Class: Boring or penetrating the earth ### FreshPatents.com Support Thank you for viewing the Drilling device and method for producing undercut holes patent info. 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