Abstract:
A holesaw mandrel assembly has a mandrel with a first shanking end, a body, and a second extending end that includes a threaded spud to receive a holesaw. A first member is secured on the second end. The first member is axially slidable on the second end. The first member also includes a friction surface to contact the holesaw. The friction surface moves between a first engaging position and a second disengaging position. A mechanism on the mandrel moves the friction surface between its engaged and disengaged positions. The mechanism includes a biased collar and a bearing race. A mating connection enables rotation of the collar which, in turn, enables the friction surface to move between its engaged and disengaged positions.

Description:
FIELD 
     The present disclosure relates to holesaws and, more particularly, a mandrel assembly for receiving holesaws. 
     BACKGROUND 
     Various types of holesaw mandrel assemblies exist in the art. The assemblies are concerned with quick release device in order to readily remove the holesaw from the mandrel assembly after use. Various types of mechanisms have been utilized in order to secure the holesaw onto the mandrel assembly, all of which enable the holesaw to be removed. Some of these mandrel assemblies utilize pins or the like which fit into the base of the holesaw. The pins hold the holesaw in position during rotation and cutting. However, since the holesaw is not torqued down onto the collar adjacent the threaded spud, the pins can be removed from the base of the holesaw and the holesaw can be easily rotated and removed from the threaded spud. 
     When small diameter holesaws are utilized, the base of the holesaw does not includes holes to receive the pins on the mandrel assemblies. This is due to the fact that the diameter of the base is too small to register with the pins. Also, during use, due to the threaded engagement of the spud with the small holesaw, the holesaw is torqued down onto the collar of the mandrel assembly. Accordingly, a wrench or the like is required to loosen the holesaw from the mandrel collar in order to remove the holesaw from the mandrel assembly. The art does not provide a small holesaw mandrel that enables the user to quickly remove, by hand, the holesaw from the mandrel assembly. Thus, it is desirable to have a mandrel assembly that enables a quick release of small diameter holesaws. 
     The assignee of the present disclosure has developed a small hole saw mandrel that enables quick removal of small diameter hole saws, as illustrated in U.S. Publication Application No. 2008/0118316 (the specification and drawings of which are expressly incorporated by reference). While this mandrel assembly performs satisfactorily, designers strive to improve the art. 
     SUMMARY 
     The present disclosure provides the art with a holesaw mandrel assembly that enables a quick release of small holesaws from the mandrel assembly. The present holesaw mandrel assembly provides a friction face that abuts the holesaw. The friction face axially moves away from holesaw into a released position. The holesaw assembly enables the friction face to be automatically moved back to its original position. 
     According to a first aspect of the disclosure, a holesaw mandrel assembly comprises a mandrel having a body with a first end to couple with a drill motor. A second end extends from the body. The second end includes a threaded spud to receive a holesaw. The second end may also include a bore to receive a pilot bit. A first member is on the second end. The first member is axially movable on the second end. A friction surface is on the first member. The friction surface is adapted to contact a base surface of the holesaw to fix the holesaw in position. The friction surface moves between a first contact and a second release position. A mechanism is on the mandrel adjacent the first member. The mechanism moves the friction surface between the first and second positions. The mechanism further comprises a biased collar and bearing race. The collar and bearing race include a mating connection to enable rotation of the collar which, in turn, enables the friction surface to move between the contact and release positions. The mating mechanism includes a pair of teeth. At least one tooth is on the collar and at least one tooth is on the bearing race. Preferably, one tooth is on the bearing race and a plurality of teeth is on the collar. A compression spring biases the collar. The collar is moved axially and rotated to engage the mating mechanism. 
     According to a second aspect of the disclosure, a holesaw mandrel assembly comprises a mandrel having a body with a first end to couple with a drill motor. A second end extends from the body. The second end includes a threaded spud to receive a holesaw. The second end may also include a bore to receive a pilot bit. A cylindrical member is on said second end. The first cylindrical member is axially movable on the second end. A friction surface is on the cylindrical member. The friction surface is adapted to contact a base surface of the hole saw such that the hole saw is fixed in position. The friction surface moves between a first contact and a second release position. A second surface is on the cylindrical member. The second surface is substantially parallel to the friction face. A mechanism is on the mandrel adjacent the first member to move the friction surface between the first and second positions. The mechanism comprises an axially biased collar and a bearing race. A plurality of balls is held by a cage. The plurality of balls is sandwiched between the cylindrical member second face and the bearing race. The bearing race includes a track and a plurality of pockets along the track to receive the plurality of balls. The collar has a plurality of mating projections extending radially inward from an inner surface of the collar. The bearing race has a mating member projecting radially outward from a circumferential surface of the bearing race to mate with one of the plurality of mating projections. A compression spring is on the mandrel first end. The compression spring is associated with the collar. The collar is moved axially toward the second mandrel end, compressing the compression spring, as the collar moves axially. The plurality of projections is aligned with the bearing race projection. The collar is rotated so that the projections mate with one another. The plurality of balls, in turn, moves in the track until the plurality of balls drops into the pockets so that the friction surface axially moves toward the first end of the mandrel to its release position to enable removal of said hole saw. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a perspective view of a holesaw mandrel assembly with an attached holesaw. 
         FIG. 2  is a cross-section view of a holesaw assembly of  FIG. 1 . 
         FIG. 3  is the same view as  FIG. 2  with the assembly in a second position. 
         FIG. 4  is an exploded perspective view of the holesaw mandrel assembly of  FIG. 1 . 
         FIG. 5  is a cross-section view of  FIG. 1  along line  5 - 5  thereof. 
         FIG. 6  is a cross-section view of an additional embodiment of the hole saw mandrel. 
         FIG. 7  is a view like  FIG. 6  in a second position. 
         FIG. 8  is an exploded perspective view of the hole saw mandrel assembly of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
     Turning to the figures, a holesaw mandrel assembly is illustrated and designed with the reference numeral  10 . The holesaw mandrel assembly  10  includes a mandrel  12 , a first axially movable member  14  and a mechanism  16  for moving the first member  14  between a first hole saw contact and second hole saw release position. 
     The mandrel  12  includes a body  18  with a first projecting end  20  and a second extending end  22 . The first projecting end  20  is cylindrical and may have an outer polygonal surface to connect the mandrel with a rotating tool, such as a drill  32 . The body  18  has an overall cylindrical shape with a first cylindrical portion  24  and a larger cylindrical shaped portion  26 . The first cylindrical portion  24  includes an aperture  28  to receive a fastener  30  that retains a pilot drill bit  32  in a bore  34 . The drill bit  32  extends through the second extending member  22 . The second cylindrical portion  26  includes a peripheral groove  36  that receives a sealing O-ring  38 . 
     The second extending end  22  of the mandrel  12  includes a first cylindrical portion  40  and a threaded spud  42 . The threaded spud  42  receives a holesaw  45  in a conventional manner. The first cylindrical portion  40  includes a pair of flat surfaces  46  that receive the first member  14 . The surfaces  46  mate with surfaces in the first member  14  to enable the first member  14  to axially slide on the second extending end  22  of the mandrel  12 . However, the flat surfaces  46  fix the first member  14  against rotation about the second extending end  22  of the mandrel  12 . 
     The first member  14  has an overall annular configuration. The first member  14  includes a bore  48  that extends through the first member  14 . The bore  48  enables the first member  14  to be positioned onto the second end  22  of the mandrel  12 . The first member  14  includes a pair of cylindrical portions  50  and  52 . The first cylindrical portion  50  extends from the second cylindrical portion  52 . A shoulder  54  is formed between the two portions  50 ,  52 . The bore  48 , extending through the first portion  50 , has a substantially circular configuration. The wall defining the bore  48 , in the second cylindrical portion  52 , includes a pair of flat surfaces  56 . The flat surfaces  56  mate with the flat surfaces  46  of the second end  22  of the mandrel  12 . Thus, the pair of flat surfaces  46 ,  56  prohibits rotation, while enabling axial movement, of the first member  14  on the second end  22  of the mandrel  12 . 
     The second cylindrical portion  52  includes a circumferential groove  58  that receives a sealing O-ring  60 . The cylindrical portion  52  includes a flat annular bottom surface  62 . 
     The mechanism  16  for moving the first member  14  between a first hole saw contact and second hole saw release position includes an outer sleeve or collar  66 . The collar  66  has an overall cylindrical shape with a central bore  68 . The collar  66  includes a lip  70 , at one end, that rests on shoulder  54  to retain the first member and mechanism  16  on the mandrel  12 . The collar  66  includes an internal cylindrical surface  72  that defines the bore  68 . The internal surface  72  includes a cavity  74  that includes a flat surface  76  that define a rectangular groove, to key or mate with a tooth  80  on bearing race  78 . Also, the interior surface includes a channel  82  that receives a C-clip  84 . The C-clip  84  is positioned behind the second cylindrical body portion  26  to retain the first member  14  and mechanism  16  onto the mandrel  12 . 
     The bearing race  78  includes a central bore  86 , with a circular configuration, that fits onto the cylindrical portion  40  of the second end  22  of the mandrel  12 . The bearing race  78  includes tooth  80  about its periphery. The tooth  80  keys or mates with the collar  66  for rotation with the collar  66  about the second end  22 . The bearing race  78  includes two surfaces  90 ,  92  parallel with one another. The surface  92  is flat. The surface  90  includes a plurality of arcuate tracks  94  to receive balls  96  that are retained by a cage  98 . The arcuate tracks  94  lead into, via ramps  99 , pockets  100 . A plurality of pins  102  project from the surface  90 , the pins retain an end  104  of the circumferential springs  106 . The other end  108  of the circumferential springs  106  is retained on the cage  98 . The springs  106  are positioned in slots  110  in the cage  98 . The cage  98  includes a smaller slot  112  that includes pin  114 , projecting from surface  90 , to limit rotational movement of the cage  98  on the bearing race  78 . 
     A thrust bearing  116  and washer  118  are positioned below the bearing race  78 . The washer  118  abuts the cylindrical portion  26  of the mandrel body. The thrust bearing  116  may be of the needle roller ball, or the like, bearing. Also, a thrust bearing made of a low friction material such as Teflon® may be used. The thrust bearing  116  provides for a substantially friction free rotation of the bearing race  78 . 
     A plurality of rollers or balls  96 , preferably three, is positioned in the tracks  94  between the bearing race surface  90  and the first member  14 , as best seen in  FIGS. 2 and 3 . The rollers  96  are sandwiched between the tracks  94  and the flat bottom surface of the first member  14 . The circumferential springs  106  are positioned to hold the cage  98  and bearing race  78  against rotation and to return the first member  14  from a second position ( FIG. 3 ) to its first original position ( FIG. 2 ). 
     The first member  14  and rotational mechanism  16  are positioned onto the mandrel  12  as illustrated in  FIGS. 1-3 . The rollers or balls  96 , in a first position, are positioned in the tracks  94  between the first member  14  and the bearing race  78 . At this time, a holesaw  45  is screwed onto the mandrel threaded spud  42 . The holesaw  45  is screwed onto the spud  42  until it contacts a friction surface  122  of the first member  14 . This is illustrated in  FIG. 2 . The holesaw  45  and mandrel assembly  10  are now ready for use. After using the holesaw  45 , the holesaw  45  may be quickly removed from the mandrel assembly  10 . However, due to rotation of the mandrel and the reverse torque caused between the holesaw  45  and the workpiece, there is a tendency for the holesaw  45  to tighten against the friction face  122  of the first member  14 . 
     Once the holesaw  45  is used, and in order to remove it from the mandrel assembly  10 , the collar  66  is rotated with respect to the mandrel body  18 . As the collar  66  is rotated, the bearing race  78 , as well as the cage  98 , is rotated with the collar  66 . As this occurs, the rollers or balls  96  roll along the tracks  94  of the bearing race  70  and flat surface of cylindrical portion  52 , respectively, as illustrated in  FIG. 2 . Also, the springs  106  are compressed. The cage  98  continues to rotate until the cage slot  112  contacts pin  114 . At this point, the balls  96  move down ramps  99  into the pockets  100 . As this occurs, the first member  14  moves axially along the mandrel second end  22  away from the holesaw  45  toward the second cylindrical portion  26  of the mandrel body  18 . As this happens, the friction face  122  moves away from the holesaw  45 . Thus, the holesaw  45  can be easily rotated and removed from the threaded spud  42 . Thus, wrenches or tools are not required to remove the holesaw  45  from the mandrel assembly  10 . 
     After the holesaw is removed and the rotational force on the collar  66  is released, the circumferential springs  106  return to their original condition in the slots  110  of the cage  98  to return the rollers or balls  96  back to their original position. Thus, the mandrel assembly  10  is ready for additional use. 
     Turning to  FIGS. 6-8 , a second embodiment is illustrated. The second embodiment is similar to the first and thus the reference numerals used in the first embodiment will be used in the second to identify the same elements. The differences are in the mating connection between the collar  66  and the bearing race  78 . 
     The mandrel assembly  10 ′ is like that described above. The outer sleeve or collar  66  differs in that it is devoid of a cavity. The internal cylindrical surface includes a plurality of projecting teeth  140 . The plurality of teeth  140  are spaced about the periphery of the cylindrical surface  72  so that upon rotation of the collar  66 , one of the plurality of teeth  140  will mate or mesh with tooth  80  on bearing race  78 . The plurality of teeth  140  each have an overall rectangular shape, however, any shape with a side surface  142  may be used. 
     Additionally, the mandrel assembly  10 ′ includes a biasing mechanism  150 . The biasing mechanism  150  includes one or more compression springs  152 . The compression springs  152  are sandwiched between the flat bottom surface of the larger cylindrical shaped portion  26  and a washer  154 . The C-clip  84  is positioned behind the washer  154  to retain the first member  14  and mechanism  16  onto the mandrel  12 . The hole saw  45  is positioned onto the mandrel  10 ′ and used as discussed above. Only the removal of the hole saw is different. 
     In order to remove the hole saw  45 , the collar  66  is moved axially in a direction toward the threaded spud  42 . As this occurs, the compression spring  152  is compressed between the large cylindrical shaped portion  26  and washer  154  as illustrated in  FIGS. 6-8 . The plurality of teeth  140  is moved axially toward the spud  42 . The side surfaces  142  are aligned with the side surface  144  of the tooth  80 . The collar  66  is rotated until one of the plurality of teeth  140  mesh or key with the bearing race tooth side face  144 . The bearing race  78  is rotated as described above until the ball  96  drop into pockets  100  enabling the hole saw  45  to be removed from the mandrel assembly  10 ′ as described above. 
     Upon removal of the rotational force, the circumferential springs  106  move the balls  96  along the ramps  99  out of pockets  100  back into tracks  94 . As this occurs, simultaneously, the compression spring  152  extends disengaging one of the pluralities of teeth  140  from the tooth  80 , returning the collar  66  back to its original position. Thus, in its original disengaged position, the collar  66  is enabled to be rotated with respect to the mandrel body  12 . 
     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.