Abstract:
A core retaining device for use with a core drill bit, which is adapted to cut a core from a material such as concrete. The core retaining device includes a core attachment mechanism for releasably connecting the core retaining device to the core; a bearing connected to the core attachment mechanism allowing the drill bit to rotate while the core attachment mechanism remains statically connected to the core; and a biasing arrangement operably connecting between the drill bit and the core via the bearing, axially biasing the core away from the material preventing the core from slipping from the drill bit. The core retaining device further includes at least one auxiliary safety feature.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 13/497,508, filed Mar. 21, 2012, which claimed priority to PCT/182009/054118 having an international filing date of Sep. 21, 2009 and claiming priority from Israel Patent Application No. 194225 filed on Sep. 21, 2008. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a construction tools, in particular a drill bit for retaining a core drilled from a material and a core retaining device. 
       BACKGROUND OF THE INVENTION 
       [0003]    In many construction situations there is a need to drill a hole in a material, e.g. concrete from a floor or wall. A core drill bit, also referred to as a circular drill bit or hole-saw, is commonly used for such purpose. The drilling process results in a concrete core being separated from the material, which can fall from the drill bit and cause damage or injury. 
         [0004]    JP 11320548 (Suetsugi) discloses a concrete drop prevention device or concrete safety catcher for a core drill. The concrete safety catcher is adapted to hang the concrete by a connecting mechanism and a concrete anchor after drilling of the concrete to prevent the concrete from falling. The anchor is arranged in the core bit to act as the concrete safety catcher when the core drill drills a cylindrical hole through the concrete. The connecting mechanism is arranged in the core bit and connects an upper wall and the concrete anchor of the core bit. 
         [0005]    JP 7171821 (Onishi, et al.) discloses a take-up device independent of rotation of a drill to eliminate the twist and break of a string belt by a method wherein a fixed base part is provided in a closed-end cylindrical drill. The take-up device is disposed downward of the fixed base part, which is connected to the take-up device by a rotating shaft, and the take-up device is rotated on ball bearings. 
         [0006]    U.S. Pat. No. 7,484,578 (Duncan) discloses an apparatus for drilling holes in a substrate wherein a mandrel is anchored to the substrate. A hollow drill bit rotates about the mandrel via a drive motor and is a guided along a length of the mandrel. 
         [0007]    U.S. Pat. No. 6,881,016 and U.S. 2004/191,014 (May) disclose a core retainer having a base plate releasably attached to a concrete floor from which a concrete core is to be removed. A brake assembly atop the plate includes a plurality of brake pads for contact with the interior of the core drill bit. The retainer is configured to fit within the core drill bit and either rotate with the core drill bit or be stationary relative thereto. Upon drilling, the plate and separated core fall toward the floor below. This movement is translated to the brake assembly by the linkage such that the brake pads engage the inner circular wall of the core drill bit at a sufficient pressure allowing for the separated core to be retained within the core drill bit. 
       SUMMARY OF THE INVENTION 
       [0008]    According to one aspect, the present invention provides an improved core retaining device for use with a core drill bit. The core drill bit is adapted for cutting a core from a material and comprises a proximal cutting portion and a distal portion. The core retaining device comprises: a core attachment mechanism for releasably connecting the core retaining device to the core of the material; a bearing connected to the core attachment mechanism allowing the drill bit to rotate while the core attachment mechanism remains statically connected to the core; and a biasing arrangement operably connecting between the drill bit and the core via the bearing, axially biasing the core in the direction of the distal portion of the drill bit. 
         [0009]    It should be understood that when terms such as connected, connecting, attached, attaching, fastened, fastening and the like are used herein the specification and claims, it is meant to denote either of a direct or indirect connection, etc. I.e. there may be one or more intermediate components, without deviating from the intention of the term connected, etc. 
         [0010]    In some embodiments, the device further comprises at least a pair of extensions extending essentially laterally outboard from the drill bit. 
         [0011]    In some embodiments, the core attachment mechanism comprises an attachment plate. 
         [0012]    According to another aspect, the present invention provides an improved core drill bit comprising: a proximal cutting portion; a distal portion comprising at least a pair of apertures; and the core retaining device as defined above. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The invention may be more clearly understood upon reading of the following detailed description of non-limiting exemplary embodiments thereof, with reference to the following drawings, in which: 
           [0014]      FIG. 1  is a schematic side sectional view of an embodiment of a core retaining device and core drill bit of the present invention; 
           [0015]      FIG. 2  is a schematic side sectional view of the embodiment of  FIG. 1  showing the device and bit after a core material has been cut; 
           [0016]      FIG. 3  is a schematic side sectional view of another embodiment of the present invention; 
           [0017]      FIGS. 4-6  are schematic views illustrating yet another embodiment of the present invention, wherein  FIGS. 4 and 5  are front and side sectional views, respectively; and  FIG. 6  is an isometric view of a portion of a biasing arrangement of the embodiment; and 
           [0018]      FIGS. 7 and 8  illustrate further embodiments where  FIG. 7  is a schematic side sectional view and  FIG. 8  is a view in the AA direction indicated in  FIG. 7 . 
       
    
    
       [0019]    The figures are intended to aid in understanding the invention and components illustrated therein may not necessarily be drawn to scale. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    In many instances, the same reference numbers may be used for similar components, despite modifications thereto, in the various embodiments described below. For the sake of brevity, description details of certain components which are known in the art are omitted. 
         [0021]      FIGS. 1 and 2  show an embodiment of a core retaining drill bit  10  comprising a core retaining device  12  for cutting a core  200  ( FIG. 2 ) from a material  202  (e.g. concrete). Drill bit  10  is of a generally typical hole-saw configuration and comprises a proximal portion  14  and a distal portion  16 . Proximal portion  14  comprises at least one cutting tooth, and typically a plurality of cutting teeth  18 . Optionally or alternatively drill bit  10  comprises a cutting edge made up of, for example, numerous very small diamonds (not shown). Distal portion  16  comprises a pair of apertures  20 . 
         [0022]    Core retaining device  12  comprises a biasing arrangement including a pair of spools  22  mounted on distal portion  16 , each spool adjacent to one of apertures  20 . Each spool  22  comprises a spring-loaded ratchet mechanism (not seen) with a setting lever  24  to set the ratchet mechanism in a ratcheting or release position. 
         [0023]    Core retaining device  12  further comprises a pair of cables  26  and a plate or elongated member  28  dimensioned to fit within the confines of drill bit  10  and disposed therein. One end of each of cables  26  is fastened or attached to one of spools  22  and the other end of each of the cable is attached or fastened to elongated member  28 , typically at or close to the ends of the member. The spring loaded ratchet mechanisms associated with spools  22  are designed to upwardly bias cables  26 . 
         [0024]    Each spool  22  typically comprises a base  30  whereat the spools are fastened or attached to distal portion  16  of drill bit  10 , for example, by a bolt/nut set  32  or any other appropriate fastening/attachment means (e.g. rivets, welding, etc). According to some embodiments, core retaining device  12  comprises more than two spools  22 , two cables  26 , etc, for example, spaced apart in a circular pattern on top of distal portion  16  of drill bit  10 . 
         [0025]    Core retaining device  12  also comprises a bearing  34  disposed at the center of elongated member  28 . Bearing  34  is attached to a core attachment mechanism  36  comprising, for example, an anchor  38  and a bolt  40  adapted to fasten to core  200  of material  202 . The number of attachment mechanisms  36  (and/or their size or design) depends on the size (weight) of core  200  and in the embodiment illustrated in  FIGS. 1 and 2  there is one attachment mechanism. Bearing  34 , which will not be described in further detail as such bearings are known, allows elongated member  28  to spin along with drill bit  10 , when operated, relative to attachment mechanism  36 , which is static with core  200 . 
         [0026]      FIG. 3  shows a further embodiment of the invention wherein there is a core attachment mechanism, now designated  36   a , which is designed for a relatively larger sized core  200   a  than core  200 . Core attachment mechanism  36   a  comprises an attachment plate  50  which is attached to bearing  34  and also to core  200   a , respectively. Attachment plate  50  can be in a variety of configurations, but typically in the form of a strip or a disk. 
         [0027]    To attach/fasten attachment plate  50  to core  200   a  there are a plurality of anchors  38  and bolts  40 ; a set of two are illustrated. If core  200   a  is large (heavy) enough to warrant it, according to particular embodiments, core attachment mechanism  36   a  comprises additional anchors  38  and bolts  40  which may be disposed juxtaposed linearly, in particular attachment plate  50  is in the form of a strip. On the other hand, if attachment plate  50  is disk shaped, anchors  38  and bolts  40  may be disposed in a circular pattern. 
         [0028]    According to some embodiments, also illustrated in  FIG. 3 , the base, now designated  30   a , comprises an extension  31  extending laterally out beyond bit  10 . Extension  31  serves a safety backup purpose in case the drill bit detaches and falls from the drill (not seen), or the drill falls. In such a case the bit and core retainer would be held by the base&#39;s extension  31  which would have fallen. 
         [0029]    Operation: 
         [0030]    With cables  26  suitably unwound from spools  22 , core attachment mechanism  32  is attached/fastened to core  200 ,  200   a  so that elongated member  28  is above the center point of the core. Upon cutting, drill bit  10  will spin into the material  202  and surround core  200 ,  200   a . This action would have a tendency to provide slack to cables  26 , however the bias of the ratchet mechanism takes up this slack and the cables wind up on their respective spools  22 , preventing core  200  from potentially slipping out of drill bit  10  (see  FIG. 2 ). 
         [0031]    Although attachment mechanism  36 , which attaches core retaining device  12  to material  202  (and what will become core  200 ,  200   a ), need remain static with the core, due to bearing  34 , spools  22 , cables  26  and elongated member  28  are free to spin along with drill bit  10  during cutting. 
         [0032]    When core  200 ,  200   a  has been completely removed from material  202 , the drill (not shown), along with bit  10  and core  200 ,  200   a  can be distanced from the opening left by the removed core, at which point core retaining device  12  can be released from the core by removing core attachment mechanism  36 ,  36   a.    
         [0033]      FIGS. 4-6  show a further exemplary embodiment of the invention wherein the biasing arrangement is disposed within the confines of drill bit  10 . Similarly to the above embodiments, the biasing arrangement operably connects between the drill bit and core  200  via bearing  34 . The biasing arrangement includes a windable connection element such as a coilable flat sheet  60  (although other such elements could be used, for example one or more cables). Coilable flat sheet  60  is wound on a rod  62  which is biased to rotate so as to tend to pull core  200  in the direction of distal portion  16  of drill bit  10  (i.e. biasing the core away from the material  202 ). Such biasing is typically constituted, for example, by a spring (not shown). Coilable flat sheet  60  is attached to member  28 , however, it should be understood that, as with the aforementioned embodiments, bearing  34  could be connected to the sheet (or cables  26 ) by various means, or even directly connected. Rod  62  is attached to drill bit  10  by a fastening element  64 . The effect of the biasing is similar to the result illustrated in  FIG. 2 . 
         [0034]    Without intention to limit, the embodiment shown in  FIGS. 4-6  is typically suited to cores smaller than those, for example, than the embodiment shown in  FIG. 3  is suited. 
         [0035]    Operation of the drill bit  10  is similar to as described above. Upon cutting, drill bit  10  will spin into the material  202  and surround core  200 . This action would have a tendency to provide slack to the windable connection element (e.g. sheet  60 ), however the bias imposed on rod  62  takes up this slack and the windable connection element winds up on the rod, preventing core  200  from potentially slipping out of drill bit  10 . 
         [0036]      FIGS. 7 and 8  show additional embodiments illustrating an auxiliary safety feature in the form of a pair of generally horizontally elongated member extensions  70  extending from the sides of elongated member  28  and extending into two respective vertical slots  72  in drill bit  10 . Elongated member extensions  70  but do not extend beyond the periphery of bit  10  and core  200 . In the case of a cable failure, extensions  70  will catch at the the bottom of slots  72  preventing core  220   a  from falling, thereby providing an auxiliary safety backup feature. Extensions  70  provide another extremely important function, namely, preventing the twisting of cables  26 . 
         [0037]      FIG. 7  further shows a drilling convenience feature in the form of a pair of spring portions  74  “embedded” in cables  26 . It may occur that during drilling, drill bit  10  will get caught or stuck in material  202  (concrete) or the drilling motor rpm will slow. Such phenomena are particularly common if the concrete has reinforcing bars (not shown). Spring portions  74  can be used to circumvent the ratchet mechanism and provide some “play” (typically of a few millimeters are required) whereby bit  10  can be raised and freed from the concrete. After that, cutting can resume. 
         [0038]    It should be understood that the above description is merely exemplary and that there are various embodiments of the present invention that may be devised, mutatis mutandis, and that the features described in the above-described embodiments may be used separately or in any suitable combination.