Patent Abstract:
A hole-saw assembly including a hole-saw having at one end a plurality of cutting teeth and at the other end a base having two holes therethrough. two shafts. The assembly includes a mandrel coaxially aligned with said hole-saw and including a body having two bores therethrough, and an annulus located on top of the body which is coaxially aligned with said mandrel and hole saw. The annulus includes two shafts co-axial with the mandrel bores, and is rotatable around its longitudinal axis from a first to a second position. In the first position the annulus shafts are aligned with the base holes allowing the shafts to be freely insertable and removable and in the second position the shafts are misaligned to lock the shafts to the base. In one embodiment the mandrel bores are shaped to accommodate rotation of the shafts, and in a further embodiment, the shafts are configures to rotate within circular mandrel bores. Such an arrangement allows the hole-saw and the mandrel to be easily and quickly mountable and demountable.

Full Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a hole-saw assembly or arrangement and in particular to a hole-saw with a base that is easily demountable and mountable from a mandrel engageable by a drill. 
         [0002]    Hole-saws are a very widely used tool for many applications. Typically a hole-saw includes a flat solid base that is locked by a drill, the base providing support for the hole-saw. Some bases include multiple diameter grooves adapted to accommodate hole-saws of different diameters. Yet others are single sized hole-saws. 
         [0003]    A universal problem when using hole-saws is that when a hole has been drilled through a material, the material that has been cut out, commonly referred to as the plug, remains embedded within the hole-saw and needs to be removed. Typically the plug is jammed tightly within the hole-saw and considerable force needs to be used to remove the plug using a sharp instrument, such as a screwdriver. However, some materials, such as plastic, possess material characteristics that make their removal difficult. The ejection of those plugs typically requires the whole hole-saw assembly to be removed from the drill to then try and force the plug out. 
         [0004]    In response to this widely recognized problem, various improved hole-saw assemblies have been proposed that try and provide an improved method of removing the plug. Whilst some of these have been found to work well, they are generally mechanically quite complicated. Further, the hole-saw is a dedicated size being limited to a pre-determined diameter and to drill larger size holes requires the use of a whole new hole-saw assembly. 
         [0005]    It is an object of the present invention to propose a hole-saw that overcomes at least some of the abovementioned problems or provides the public with a useful alternative. 
       SUMMARY OF THE INVENTION 
       [0006]    Therefore in one form of the invention there is proposed a connector assembly including: 
         [0000]    an annulus defining a longitudinal axis through its centre, said annulus including a connecting means;
 
a co-axial driving means adapted to rotate around said longitudinal axis and adapted for rotational engagement with said annulus, said annulus being adapted to rotate between a first and a second position relative to said driving means; and
 
a device including a locking base co-axial with said annulus and driving means, said locking base adapted to rotate around the longitudinal axis and engage the annulus connecting means when in said first position to prevent longitudinal relative motion of said base, driving means and annulus.
 
         [0007]    Preferably when said annulus is in said second position, the locking base is free for longitudinal motion from said driving means and annulus. 
         [0008]    In preference said connecting means extends inwardly in the opposite direction. 
         [0009]    In preference said annulus is biased to said first position. 
         [0010]    In a further form of the invention there is proposed a connector assembly including: 
         [0000]    an annulus having a longitudinal axis sais locking annulus including a longitudinally extending projection;
 
a driving means coaxially aligned with said annulus and including a body having a passage coaxially aligned with said projection;
 
a device including a locking base which is coaxially aligned with said driving means and annulus, said locking base including a passage, said annulus rotatable around its longitudinal axis from a first to a second position wherein in said first position said projection is aligned with said locking base passage and said driving means passage, allowing said projection to be freely insertable and removable and in said second position said projection being misaligned thereby locking the projection shoulder to said driving means.
 
         [0011]    Preferably there are at least two projections co-axially aligned with two driving means passages and two locking base passages. 
         [0012]    In a still further form of the invention there is proposed a rotational tool support assembly including: 
         [0000]    a base associated with said tool, said base including two holes;
 
an annulus coaxially aligned with said base and adapted to support two shafts, said annulus rotatable around its longitudinal axis from a first to a second position;
 
a driving means coaxially aligned with said base and including a body having two bores therethrough coaxially aligned with said shafts, wherein when said annulus is in said first position said shafts are aligned with said base allowing said shafts to be freely insertable and removable, and in said second position said shafts being misaligned thereby locking the shafts to said base.
 
         [0013]    In a yet further form of the invention there is proposed a hole-saw assembly including: 
         [0000]    a hole-saw having at one end a plurality of cutting teeth and at the other end a base including two holes;
 
a mandrel coaxially aligned with said hole-saw and including a body having two bores therethrough;
 
an annulus rotatably engageable with said mandrel, said annulus including two shafts coaxially aligned with said bores and being moveable with respect to said mandrel from a first to a second position, wherein in said first position said shafts are aligned with said base holes allowing said shafts to be freely insertable and removable and in said second position said shafts being misaligned thereby locking the shafts to said base.
 
         [0014]    Preferably said annulus is biased to said second position. 
         [0015]    Preferably said base forms part of the hole-saw body which when connected to the mandrel is prevented from rotational motion relative thereto. 
         [0016]    Alternatively said base is in the form of a locking ring which when attached to the mandrel is prevented from rotational motion relative thereto, said locking ring including an attachment means for attaching one or more hole-saws thereto. 
         [0017]    Preferably said hole-saw includes a threaded inner bore adapted to engage a threader outer projection extending from said locking ring. 
         [0018]    Preferably said shafts include a flute adjacent said outer end and a cap on said outer end, the cap having an inner surface adapted to engage the base when said annulus is in said second position to thereby lock the shafts from longitudinal movement from the base. 
         [0019]    In preference said hole-saw assembly includes a drill-bit mounted on said mandrel, said drill-bit extending through and beyond said hole-saw. 
         [0020]    In a still further form of the invention there is proposed a hole-saw assembly including: 
         [0000]    a hole-saw having a longitudinal body with a plurality of cutting teeth at one end and a threaded inner bore at the other end;
 
a base including a disk co-axially aligned with said hole-saw body and including a threaded projection extending longitudinally therefrom, said projection adapted to be engaged by said hole-saw threaded bore, said disk further including two holes;
 
a mandrel co-axially aligned with said base and hole-saw and including a body having a drill bit extending therefrom, said drill bit passing through central apertures in the base and hole-saw, said mandrel further having two bores therethough; and
 
an annulus resting on top of said mandrel and including a pair of shafts extending in a longitudinal direction towards the hole-saw, each said shaft including a column adjacent said annulus a flute adjacent a shaft outer end and a chamfered cap, the diameter of said cap equal to the diameter of said column, said annulus being rotatable between a first and a second position wherein in the first position said shafts are aligned with the holes in the base, and in said second position are misaligned, the thickness of the mandrel body and the base being such that the flute is engaged by said base with the cap extending beyond a shoulder thereof so that when the annulus is in said second position the base locks said shafts in a relative longitudinal position, said mandrel bores being of a shape to accommodate rotation of the columns.
 
         [0021]    In a yet further form of the invention there is proposed a hole-saw assembly including: 
         [0000]    a hole-saw having a longitudinal body with a plurality of cutting teeth at one end and a base at the other having a threaded inner bore and two holes;
 
a mandrel co-axially aligned with said hole-saw base and including a body having a drill bit extending therefrom, said drill bit passing through the hole-saw inner bore, said mandrel further having two apertures therethough; and
 
an annulus resting on top of said mandrel and including a pair of shafts extending in a longitudinal direction towards the hole-saw, each said shaft including a column adjacent said annulus and a chamfered cap, said annulus being rotatable between a first and a second position wherein in the first position said shafts are aligned with the holes in the base, and in said second position are misaligned, the thickness of the mandrel body and the hole-saw base being such that the column is engaged by said base with the cap extending beyond the hole-saw base so that when the annulus is in said second position the base locks said shafts in a relative longitudinal position, said mandrel bores being of a shape to accommodate rotation of the columns.
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several implementations of the invention and, together with the description, serve to explain the advantages and principles of the invention. In the drawings: 
           [0023]      FIG. 1  is an exploded, front perspective view of a hole-saw assembly according to a first embodiment of the present invention; 
           [0024]      FIG. 2  is an exploded, rear perspective view of the hole saw assembly of  FIG. 1 ; 
           [0025]      FIG. 3  is a side view of the hole-saw assembly of  FIG. 1 ; 
           [0026]      FIG. 4  is a partial, cross-sectional view of the hole saw assembly of  FIG. 3  through line A-A; 
           [0027]      FIG. 5  is a top view of the hole-saw assembly of  FIG. 1 ; 
           [0028]      FIG. 6  is a partial, cross-sectional view of the hole saw assembly of  FIG. 5  through line B-B; 
           [0029]      FIG. 7  is an exploded, front perspective view of a hole-saw assembly according to a second embodiment of the present invention; 
           [0030]      FIG. 8  is an exploded, rear perspective view of the hole saw assembly of  FIG. 7 ; 
           [0031]      FIG. 9  is a side view of the hole-saw assembly of  FIG. 7 ; 
           [0032]      FIG. 10  is a partial, cross-sectional view of the hole saw of  FIG. 9  through line A-A; 
           [0033]      FIG. 11  is a top view of the hole-saw assembly of  FIG. 7 ; and 
           [0034]      FIG. 12  is a partial, perspective view of the hole saw assembly of  FIG. 12  through line B-B. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0035]    The following detailed description of the invention refers to the accompanying drawings. Although the description includes exemplary embodiments, other embodiments are possible, and changes may be made to the embodiments described without departing from the spirit and scope of the invention. Wherever possible, the same reference numbers will be used throughout the drawings and the following description to refer to the same and like parts. 
         [0036]      FIGS. 1 to 6  illustrate a hole-saw assembly  10   a  according to a first embodiment of the present invention, whilst  FIGS. 7-12  illustrate a hole saw assembly  10   b  according to a second embodiment. It is to be understood that similar features between the first and second embodiments will be referred to using like numbers. 
         [0037]    Referring firstly to  FIGS. 1 to 6  there is shown hole-saw assembly  10  including a hole-saw  12 , a base or locking ring  14 , and mandrel  16 . 
         [0038]    The hole-saw  12  includes a cylindrical body  18  having cutting teeth  20  at one end thereof. At the opposite end the hole-saw  12  includes a threaded bore  22  (with inner threads), the outer surface of the hole-saw body  18  adjacent the bore  22  including circumferentially disposed shoulders  24  to enable a tool (not shown) such as a wrench to engage the hole-saw  12  for rotational movement thereof. 
         [0039]    The base  14  includes a disk  26 . Extending co-axially from the disk  26  is a threaded projection  28  (with outer threads), of a size and shape to be engaged by the bore  22  thus enabling hole-saw  12  to be tightly screwed onto the base. The disk  26  includes shoulders  30  for engagement by a tool. Those skilled in the art will appreciate that by the use of two tools, one on the hole-saw  12  and one on the base  14 , the hole-saw may also be removed from the base. 
         [0040]    The mandrel  16  includes a longitudinal body  32  removably affixed to which is a drill bit  34  extending co-axially therefrom. Extending alongside and in the same direction as the drill bit  34  are two diametrically opposed locking pins  36  and  38  adapted to engage respective, correspondingly positioned bores  40  and  42  in the base  14 , when the base  14  is placed on the mandrel  16 . This engagement effectively locks the base  14  to the mandrel body  32  and thereby prevents rotational motion of the base  14  and hence the attached hole saw  12  relative thereto. Extending in the opposite direction to the drill bit  34  is an arbour  44  having shoulders  46  and is insertable into a drill (not shown) as is well known in the art. The disk  26  includes two further diametrically opposed holes  48  and  50  which are radially offset from bores  40  and  42  by approximately 90 degrees. The holes  48  and  50  and their purpose is described in further detail below. 
         [0041]    A co-axial annulus  52  is located at the base of the mandrel body  32  and extending from the annulus  52  in the same direction as the drill bit  34  are two diametrically opposed, identical shafts  54  and  56  located adjacent the edge of the annulus  52 . The mandrel body  32  includes two substantially elliptical holes  55  and  57  whose location and size is such to allow for the insertion, passage through, and slight rotation of respective shafts  54  and  56  respectively, as will become obvious. 
         [0042]    Since the two shafts  54  and  56  perform the same function, that is to prevent base  14  and attached hole saw  12  from longitudinal movement, only one will be described. It is however to be understood that the description applies equally well to both. 
         [0043]    Shaft  54  includes a column  58  extending from the annulus  52  and attached to the annulus using well-known techniques such as threads or press fitting. Adjacent the outer end of the column  58  is a flute  60 , the column then having a chamfered cap  62  fixed on its outer end whose outer diameter is equal to the diameter of the column  58 . 
         [0044]    The co-axial annulus or ring  52  is rotatably movable with respect to the mandrel body  32  between a first and a second position, the biasing arrangement being as follows. The annulus  52  includes a groove  64  within which is located the biasing means, typically a spring (not shown). At one end of the groove  64  is located a channel  66  within which slidably moves a pin  68 . The pin  68  engages a correspondingly shaped bore  69  in the mandrel body  32  whereby it is locked into place when the mandrel  16  is placed on top of the annulus  52 . The length of the channel  66  within which the pin  68  can effectively move therefore limits rotation of the annulus  52 . 
         [0045]    The length of the mandrel body  32  is the same length as that of the shaft column  58  such that when the shaft  54  is inserted into body  32  the flute  60  and the cap  62  protrude beyond the body  32 . Those skilled in the art will appreciate that the shaft flute  60  and cap  62  extend into the base  14  when it is placed on top of the mandrel body  16 . 
         [0046]    As mentioned, the base  14  includes two further holes  48  and  50 . Hole  48  and  50  are also identical and so only will be described. The portion of the hole  48  adjacent the upper surface of the disk  26  is partially enlarged with respect to the lower side of the disk  26 , to thereby provide an inner shoulder  70 . Accordingly, the base holes  48  and  50  are of a first circular cross-section only for the length of the flute  60  from the bottom surface of the disk  26 , and are then enlarged to accommodate for the rotational movement, of the annulus  52  to lock and unlock the shafts  54  and  56  to the mandrel  16 . Therefore, when the annulus  52  is in the second position with the shaft  54  fully inserted into the mandrel  16 , the inner shoulder  70  is engaged by the lip  72  of the cap  62 , effectively preventing the shaft  54  from being withdrawn from the mandrel  16 . In locking the base  14  and hence the hole-saw  12  to the mandrel  16  in this way, the hole-saw is ready to be used to drill a hole. 
         [0047]    The annulus  52  is biased to the second position, that is, the locked position and a rotational force has to be applied to rotate it to the first position to enable for the withdrawal of the shafts  54  and  56 . The elliptical apertures  55  and  57  are dimensioned to allow for movement of the shafts  54  and  56  between the first and second positions. The rotation from the biased second position to the first position is generally in the same direction as the rotation of the drill. 
         [0048]    The skilled addressee will now appreciate that the present hole-saw assembly of the present invention enables for the very quick mounting and unmounting of a hole-saw and base to a mandrel that is already mounted in a drill. Since the diameter of the hole-saw is independent of the size of the base and hence the mandrel, one may have a number of hole-saws that they simply mount and unmount to and from the mandrel by rotating the annulus between the first and second positions. 
         [0049]    However, to further assist in quick mounting of the hole-saw base  12  to the mandrel  16 , the lower circular edges of holes  48  and  50  on the underside of the disk  26 , that is the side which abuts with upper surface of the mandrel body  32 , may be tapered or chamfered. As the shafts  54  and  56  are inserted into the mandrel  16  through apertures  55  and  57  and holes  48  and  50  of the base  14 , the chamfered cap  62  forces the annulus  52  to rotate to the first position. As the cap  62  passes beyond the inner shoulder  70  of the base  14 , the biasing means causes it to snap back into its biased position thereby locking the base  14  and hence the hole-saw  12  to the mandrel  16 . This provides the tool operator with an automatic “snap-fit” arrangement. 
         [0050]    The mandrel body  32  is typically clamped onto the drill bit  34  using a grub screw  72 . However, it may equally well be attached, as would be known by the skilled addressee, using other common techniques. The annulus  52  is secured in its position using a circlip  74 . 
         [0051]    The projection  28  of the base  14  illustrated in  FIGS. 1-6  may be made significantly longer than is currently known. Alternatively, the projection  28  could include two different diameters, the larger of which is located adjacent the disc  26 . Both of these configurations enable two hole-saws to be mounted on the one base. This is a particularly useful feature where the operator may wish to drill a bigger hole over an existing hole wherein the size of the smaller hole-saw is chosen to be the size of the already existing hole. The smaller hole-saw is then used as an effective guide center to be able to cut out the bigger hole in a symmetrical arrangement. 
         [0052]    Turning now to the second embodiment of the present invention illustrated in  FIGS. 7-12 , where there is shown a hole-saw assembly  10   b  in which the hole-saw  12  is directly lockable to the mandrel body  16  without the need for a base/locking ring. It is to be understood that like parts are referred to using like numbers and may not be described again. 
         [0053]    The co-axial annulus or ring  76  is similar to that previously described in that it is rotatably movable with respect to the mandrel body  78  between a first and a second position. The shafts  80  and  82  extend from the same position and in the same direction and again, only shaft  80  will be described in the following paragraphs given that shaft  82  is identical. 
         [0054]    Shaft  80  includes a column  84  having a smaller diameter to that of shaft  54  of the first embodiment. The diameter is approximately equivalent to that of the flute  60  in assembly  10   a . So in the present embodiment there is effectively no longer a flute portion, just a thin column  84  terminating in a chamfered cap  86 . The benefit of having a column of this size and shape is so that elliptical apertures do not need to be drilled into the mandrel body  78 . The circular apertures  88  and  90  in the mandrel body  78  are therefore positioned and sized to allow for the insertion, passage through, and rotation of the respect shafts  80  and  82  between the first and second positions. The diameter of each aperture is slightly larger than the chamfered caps. 
         [0055]    Those skilled in the art would realize the cost and time benefits in having circular apertures  88  and  90  as opposed to the elliptical apertures proposed in assembly  10   a  which require skilled machining of the mandrel  16 . 
         [0056]    Extending alongside and in the same direction as the drill bit  34  are two diametrically opposed locking pins  92  and  94  adapted to engage correspondingly positioned holes  96  and  98  extending through the base  100  of the hole-saw body  102 . This engagement effectively locks the hole-saw  12  to the mandrel  16  and thereby prevents rotational motion of the hole-saw  12  relative thereto. The hole-saw base  100  includes two further diametrically opposed holes  104  and  106  which are radially offset from holes  96  and  98  by approximately 90 degrees. The purpose of holes  104  and  106  is described in further detail below. 
         [0057]    The length of shaft  80  is such that when inserted into the mandrel  16 , the cap  86  and a short portion of the column  84  which is approximately equivalent to the width of the hole-saw base  100 , protrude beyond the mandrel body  78 . Those skilled in the art will appreciate that the protruding portion of shaft column  84  and cap  86  extend into the diametrically opposed holes  96  and  98  at the base of the hole-saw body when it is placed on top of the mandrel  16 . 
         [0058]    The hole-saw  12  is locked in place by substantially the same means as described above in the first embodiment whereby an inner shoulder  108 , which is essentially the internal surface of the hole-saw base  100 , is able to accommodate for the rotational movement of the annulus  76  to lock and unlock the shafts  80  and  82  to the mandrel  16 . Therefore, when the annulus  76  is in the second position with the shaft  80  fully inserted into the mandrel  16 , the inner shoulder  108  is engaged by the lip  110  of the cap  86 , effectively preventing the shaft  80  from being withdrawn from the mandrel  16 . Once again, in locking the hole-saw  12  to the mandrel  16 , the hole-saw is ready to be used to drill a hole. 
         [0059]    As with the first embodiment, the annulus  76  is biased to the second position being the locked position, and a rotational force has to be applied to rotate it to the first position to enable the withdrawal of shafts  80  and  82 . The rotation from the biased second position to the first position is generally in the same direction as the rotation of the drill. Again, the holes  106  and  108  may be tapered or chamfered adjacent the underside of the base to allow for the abovementioned “snap-fit” type connection. 
         [0060]    Further advantages and improvements may very well be made to the present invention without deviating from its scope. Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope and spirit of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus. 
         [0061]    In any claims that follow and in the summary of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprising” is used in the sense of “including”, i.e. the features specified may be associated with further features in various embodiments of the invention.

Technology Classification (CPC): 8