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

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to an improved 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 and 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 predetermined diameter and to drill larger size holes requires the use of a whole new hole-saw assembly.  
         [0005]     A still further limitation of existing hole-saw assemblies is that they can at any one time only accommodate one hole-saw and do not enable the simultaneous use of two different sized hole-saws.  
         [0006]     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.  
         [0007]     It is a further object of the present invention to provide a hole-saw assembly where the hole-saw can be easily removed from the mandrel.  
         [0008]     It is still a further object of the present invention to provide for a hole-saw assembly wherein different sized hole-saws may be easily mounted for use with a drill.  
         [0009]     It is yet a further object of the present invention to provide for a hole-saw assembly wherein at least two different sized hole-saws may be used simultaneously in drilling a larger hole.  
       SUMMARY OF THE INVENTION  
       [0010]     Therefore in one form of the invention there is proposed a connector assembly including: 
    a base adapted to rotate around a longitudinal axis and including an attachment means for attaching a device thereto, said base further including a connecting means;     a co-axial driving means adapted to rotate around said longitudinal axis and adapted for rotational engagement of said base connecting means;     a co-axial locking ring adapted to rotate around its longitudinal axis and further adapted to rotate between a first and a second position relative to said driving means, said locking ring adapted to engage said base connecting means when in said first position to prevent longitudinal relative motion of said base, driving means and said locking ring.    
 
         [0014]     In preference when said locking ring is in said second position, said base is free for longitudinal motion from said driving means and locking ring.  
         [0015]     In preference said attachment means extends outwardly in the longitudinal direction and said connecting means extends inwardly in the opposite direction.  
         [0016]     In preference said locking ring is biased to said first position.  
         [0017]     In a further form of the invention there is proposed a connector assembly including: 
    a boss having a longitudinal axis said boss including an attachment means extending longitudinally in one direction said boss further including a projection extending in an opposite direction, said projection including a shoulder;     a driving means coaxially aligned with said boss and including a body having a passage coaxially aligned with said projection;     a locking ring coaxially aligned with said driving means and boss and including a passage, said locking ring rotatable around its longitudinal axis from a first to a second-position, wherein in said first position said locking ring passage is aligned with said driving means passage and said projection allowing said projection to be freely insertable and removable and in said second position said locking ring passage being misaligned thereby locking said projection shoulder to said driving means.    
 
         [0021]     Preferably there are at least two projections co-axially aligned with two driving means passages and two locking ring passages.  
         [0022]     In a still further form of the invention there is proposed a rotational tool support assembly including: 
    a boss adapted at one end to support a tool and at the other end two shafts;     a driving means coaxially aligned with said boss and including a body having two bores therethrough coaxially aligned with said shafts;     a locking ring coaxially aligned with said driving means and boss and including two holes, said locking ring rotatable around its longitudinal axis from a first to a second position, wherein in said first position said locking ring holes are aligned with said bores and said shafts allowing said shafts to be freely insertable and removable and in said second position said holes being misaligned thereby locking said shafts to said locking ring.    
 
         [0026]     In a yet further form of the invention there is proposed a hole-saw assembly including: 
    a hole-saw having at one end a plurality of cutting teeth and at the other end two shafts;     a mandrel coaxially aligned with said hole-saw and including a body having two bores therethrough coaxially aligned with said shafts;     a locking member forming part of said mandrel and including two holes, said locking member moveable from a first to a second position, wherein in said first position said locking member holes are aligned with said bores and said shafts allowing said shafts to be freely insertable and removable and in said second position said holes being misaligned thereby locking said shafts to said annulus.    
 
         [0030]     Preferably said locking member is biased to said second position.  
         [0031]     Preferably said assembly includes a base from which therein extend the two shafts said base including a mounting means for mounting of a hole-saw thereon.  
         [0032]     Preferably said hole-saw includes a threaded inner bore adapted to engage a threader outer projection extending from said base.  
         [0033]     In preference 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 locking member when said locking member is in said second position to thereby lock the shafts from longitudinal movement from the locking member.  
         [0034]     Preferably said assembly includes a drill-bit mounted on said mandrel, said drill-bit extending through and beyond said hole-saw.  
         [0035]     In preference said locking member is an annulus coaxially aligned with sad mandrel.  
         [0036]     In preference said annulus is rotatable around its longitudinal axis from said first to said second position.  
         [0037]     In a further form of the invention there is proposed a hole-saw assembly including: 
    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 including a pair of shafts extending in a. longitudinal direction away from said hole-saw, each said shaft including a column adjacent said base a flute adjacent said shaft outer end and a chamfered cap, the diameter of said cap equal to the diameter of said column;     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 said hole-saw, said mandrel further having two bores therethrough co-axially aligned with said base shafts;     an annulus resting on top of said base and being rotatable between a first and a second position, said annulus further including two holes wherein said holes in the first position are aligned with the bores in said mandrel and the shafts of said base, and in said second position are misaligned, the thickness of the mandrel body and annulus being such that the flute is engaged by said annulus with the cap extending beyond the annulus so that when in said second position the annulus locks said shafts in a relative longitudinal position.    
 
         [0042]     In preference said assembly includes an inner and an outer hole-saw mounted on said mandrel, said inner hole-saw extending beyond said outer hole-saw.  
         [0043]     In a still further form of the invention there is proposed a hole-saw assembly for use in a drilling machine including a hole-saw and a mandrel assembly characterised in that there is included a biased member which when in a first position, is adapted to engage with and lockingly retain said hole-saw when it is mounted onto said mandrel and upon movement to a second position, said biased member is adapted to unlock and release said hole-saw allowing said mandrel and said hole-saw to be separated.  
         [0044]     Still a further advantage is that by utilising a boss, commonly available hole-saws may be used with the mandrel.  
         [0045]     In a yet further form of the invention there is proposed a connector assembly including: 
    a base having a longitudinal axis and including an attachment means for attaching a device thereto, said base further including a connecting means;     a co-axial mating means adapted engage said base;     a co-axial locking ring adapted to rotate around its longitudinal axis between a first and a second position relative to said mating means, said locking ring adapted to engage said base connecting means when in said first position to prevent longitudinal relative motion of said base, mating means and said locking ring.    
 
         [0049]     Such an assembly may be used to connect various objects together, with multiple assemblies being used to connect larger devices. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0050]     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:  
         [0051]      FIG. 1  is an exploded isometric view of a hole-saw assembly embodying the present invention;  
         [0052]      FIG. 2  is a side view of the hole-saw assembly base mandrel embodying the present invention;  
         [0053]      FIG. 3  is a top view of the mandrel of  FIG. 2 ;  
         [0054]      FIG. 4  is a side view of the hole-saw assembly as the hole-saw and base is mounted on the mandrel;  
         [0055]      FIG. 5  is a partial cross-sectional view illustrating the engagement of the hole-saw base with the mandrel;  
         [0056]      FIG. 6  is a detailed partial underside perspective view of the locking mechanism of the mandrel when in a locked or biased position;  
         [0057]      FIG. 7  is the mechanism of  FIG. 6  when in an unlocked position;  
         [0058]      FIG. 8  is a perspective view of an alternate hole-saw and base embodying the present invention when formed in one piece;  
         [0059]      FIG. 9  is a perspective view of a large diameter hole-saw and base embodying the present invention;  
         [0060]      FIG. 10  is a perspective view of a hole-saw assembly embodying the present invention and having two hole-saws, one within the other for guiding the larger hole-saw;  
         [0061]      FIG. 11  is a perspective view of a hole-saw assembly according to yet a further embodiment of the invention and where the shafts of the hole-saw base are housed within the mandrel and do not protrude through its upper surface;  
         [0062]      FIG. 12  is a perspective view of the bole-saw and base of  FIG. 11  illustrating the shorter shafts; and  
         [0063]      FIG. 13  is a cross-sectional view of the hole-saw assembly of  FIG. 11  when the hole-saw and base are mounted to the mandrel. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0064]     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.  
         [0065]     Referring to FIGS.  1  to  5  there is shown a hole-saw assembly  10  including a hole-saw  12 , base  14 , and mandrel  16 .  
         [0066]     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.  
         [0067]     The base  14  includes 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 form the base.  
         [0068]     Extending adjacent the edge of the disk  26  and in the opposite direction to the projection  28  are two identical shafts  32  and  34 . Since the shafts perform the same function and operate in exactly the same way, only one will be described in the rest of the description. It is however to be understood that the description applies equally well to both.  
         [0069]     Shaft  32  includes a column  36  extending from the disk and attached to the disk using well-known techniques such as threads or press fitting. Adjacent the outer end of the column  36  is a flute  40 , the column then having a chamfered cap  42  fixed on its outer end whose outer diameter is equal to the diameter of the column  36 .  
         [0070]     The mandrel  16  includes a longitudinal body  44  extending co-axially from and rotationally affixed to which is a drill bit  46 . Extending in the opposite direction to the drill bit  46  is an arbour  48  having shoulders  50  and is insertable into a drill (not shown) as is well known in the art. The body  44  includes two holes  52  and  54  whose location and size is such to allow for the insertion and passage through of shafts  32  and  34  therein, shaft  32  insertable into hole  52  and shaft  34  insertable into hole  54 . Typically, the holes  52  and  54  are of a diameter to effectively enable the shaft to be mounted to the body  44 .  
         [0071]     The length of the body  44  is the same length as that of the shaft column  36  from the disk  26  to the flute  40  so that when the shaft  32  is inserted into body  44  the flute and the cap protrude beyond the body  44 .  
         [0072]     Located on top of the body  44  is a co-axial annulus or ring  56 , rotatably movable between a first and a second position. The annulus  56  includes two correspondingly shaped and sized apertures  58  and  60  that are aligned with the holes  52  and  54  when the annulus is in the first position and are misaligned when the annulus is in the second position.  
         [0073]     Those skilled in the art will appreciate that the shaft flute  40  and cap  42  then extend into the annulus when it is aligned with the body. The thickness of the annulus  56  is equal to the width of the flute  40  so that when fully inserted into the mandrel only the cap  42  extends beyond the surface plane of the annulus  56 .  
         [0074]     When the annulus is in the second position with the shaft  32  fully inserted into the mandrel, the upper surface of the annulus  62  engages the lip  64  of the cap  42 , effectively preventing the shaft  32  from being withdrawn from the mandrel  16 . This effectively therefore locks the base  14  and hence the hole-saw  12  to the mandrel  16  enabling the hole-saw to be used to drill a hole.  
         [0075]     The annulus 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  32  and  34 . The rotation from the biased second position to the first position is generally in the same direction as the rotation of the drill.  
         [0076]     The skilled addressee will now appreciate that the present hole-saw assembly enables for the very quick mounting and unmounting of a hole-saw and a 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.  
         [0077]     However, to further assist in quick mounting of the hole-saw base  14  to the mandrel  16 , the circular edges  66  of holes  58  and  60  on the underside  68  of the annulus  56 , that is in the side that faces the base  44 , may be tapered or chamfered. As the shafts  32  and  34  are inserted into the mandrel through the holes  52  and  54  and apertures  58  and  60 , the cap forces the annulus to rotate to the first position. As the cap passes beyond the upper surface of the annulus, the biasing means causes it to snap back into its biased position thereby locking the base the hence the hole-saw to the mandrel. This provides the tool operator with an automatic “snap-fit” arrangement.  
         [0078]     Body  44  is typically clamped on the drill bit  46  using a grub screw  70 . However, it may equally well be attached, as would be known by the skilled addressee, using other common techniques.  
         [0079]     The annulus is secured in its position using a circlip  72 . To prevent rotation of the circlip that may effectively block one of the apertures  58  or  60 , a cusp (not shown) or projection may be used to lock the circlip relative to the annulus.  
         [0080]     Referring now to  FIGS. 6 and 7  there is shown in detail the annulus  56  and specifically the biasing arrangement. The annulus includes a groove  74  within which is located the biasing means, typically a spring  73 . At one end of the groove is located a channel  76  within which slidably moves a pin  78 . The pin engages a correspondingly shaped bore (not shown) in the body  44  whereby it is locked into place when the annulus is placed on top of the body. The length of the channel  76  within which the pin can effectively move, the two positions illustrated in  FIGS. 6 and 7 , then limits rotation of the annulus as shown in  FIG. 3 .  
         [0081]     In a preferred embodiment, the hole-saw may be manufactured integrally with the shafts that engage the mandrel. This embodiment is illustrated in  FIG. 8  wherein one can see that the hole-saw  80  has integral shafts  82  and  84  whose shape and function is the same as discussed earlier. Such a hole-saw may be for example be manufactured using machining or metal casting processes. An advantage of this is in the reduction of parts for manufacture resulting in reduced costs.  
         [0082]     To assist in handling the shafts they may include shoulders  86  that can be engaged by a tool, the shoulder also a feature of the earlier embodiment.  
         [0083]     In the case where the hole-saw is of a significant diameter, as illustrated in  FIG. 9 , the hole-saw  88  may be attached to the base  90  not by using threaded engagement members but rather by the use of screws  92  and  94  that pass through apertures  96  and  98  in the bottom of the hole-saw and engage the ends of shafts  100  and  102  respectively thereby locking the hole-saw to the base  90 .  
         [0084]     In an alternate embodiment, the projection  28  of the base  14  illustrated in  FIGS. 1-5  may be made significantly longer than is currently known. This would then 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. As illustrated in  FIG. 10  the hole-saw assembly according to this preferred embodiment includes a smaller hole-saw  104  that extends beyond a larger hole-saw  106  in the longitudinal direction. The diameter of the smaller hole-saw  104  is chosen so that its outside surface  108  engages the inner surface of hole  110  in wall  112 . The smaller hole-saw  104  ensures that when hole-saw  106  engages the wall, it does not gyrate ensuring that the larger hole  114  to be cut-out in the wall is co-axial with the smaller hole  10 .  
         [0085]     Illustrated in FIGS.  11  to  13  is a hole-saw assembly according to a further preferred embodiment of the present invention. In this embodiment, the hole-saw  12  and base  26  are of the same type as described above. However the total length of the shafts  116  and  118  are somewhat shorter, the shafts still having flutes  40  and caps  42 . The shorter shafts, assuming that the base and the annulus are the same size, results in the shafts not protruding beyond the annulus as was the case in the earlier embodiment. This is clearly illustrated in FIGS.  11  and  13  where one can see that the shafts  116  and  118  do not protrude beyond the upper surface  120  of the annulus  122 .  
         [0086]     Since the shafts  116  and  118  no longer protrude beyond the annulus  56 , the previously described locking technique of the mandrel to the shafts is no longer available. For that reason, holes  124  and  126  adjacent the upper surface  120  of the annulus  56  are partially enlarged to provide an inner shoulder  128  that can be engaged by the lip  64  of the cap  42 . Accordingly, the annulus holes  124  and  126  are of a circular cross-section only for the length of the flute  40  from the annulus bottom surface  68 , and are then enlarged to accommodate for the rotational movement of the annulus  56  to lock and unlock the shafts  116  and  118  to the mandrel.  
         [0087]     This embodiment overcomes the need for a dimple or the like to prevent the clip  72  for any rotational movement. It also provides for a more visually pleasing appearance and reduces the risk of the caps catching.  
         [0088]     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.  
         [0089]     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.