Patent Publication Number: US-8113749-B2

Title: Auger bit including a reamer

Description:
BACKGROUND OF THE INVENTION 
     The present invention generally relates to hand tools, and more particularly to an auger bit for a drill. 
     Drill bits come in all different shapes and sizes and are used for a variety of purposes. Typically, drill bits are used to form a recess or through hole in a material such as metal or wood. One type of drill bit is an auger bit, which is primarily used to form recesses and holes in wood. In operation, the auger bit is attached to a drill and rotated to enable a cutting edge on the auger bit to remove material from the wood to form the recess or hole. A long deep spiral flute on the auger bit moves the removed material out of the recess or hole so that the material doesn&#39;t obstruct the drilling operation. 
     Auger bits are commonly used in the construction industry. In particular, electricians, plumbers and other contractors need to drill holes through wood framing studs to run conduit, pipes, wires and other components through the studs. Typically, an auger bit is attached to a motorized power drill. The power drill rotates the auger bit to drill one or more holes in a wood stud or other workpiece. 
     During drilling, it is common to encounter nails and other fasteners that are in the wood for securing wood framing studs together or for other purposes. The contact between the auger bit and the fasteners can dull, damage or break the cutting edges and surfaces of the auger bit. As the auger bit gets duller, the bit fails to effectively cut the wood, which causes heat buildup and possible binding of the bit in the wood. Additionally, the complex shape of an auger bit makes it difficult to re-sharpen, which decreases the useful life of the bit. 
     Typically, after an auger bit cuts and forms a hole in a piece of wood, the inside surface of the hole is rough and includes bits, fragments and particles of wood that extend at least partially into the hole. The rough inside surface of the hole can cause conduit, pipes, wires and the like to get snagged or hung up on the inside surface. 
     A common method in metal drilling to assure an accurate size hole with a good surface finish is to use a reamer or reaming bit. A reaming bit is a multipoint cutting tool with straight cutting edges that comes in many different shapes and sizes. 
     It would therefore be beneficial to provide a drill bit including a reaming portion for drilling accurate, smooth holes in wood. 
     SUMMARY OF THE INVENTION 
     Embodiments of the invention comprise an auger bit for use with a power drill including an elongated member including a first end and an opposing second end, a helical surface having a central axis, where the helical surface defines at least one flute, a head portion integrally formed with the first end of the elongated member and including a primary cutting edge adapted to engage and remove material from a workpiece and a secondary cutting edge adapted to engage and remove additional material from the workpiece, a threaded tip integrally formed with the head portion and a shank integrally formed with the second end of the elongated member and adapted to engage the drill. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side perspective view of an auger bit including a reaming portion embodying the present invention; 
         FIG. 2  is a side perspective view of the auger bit shown in  FIG. 1  showing another side of the auger bit; 
         FIG. 3  is a top view of the auger bit shown in  FIG. 1 ; 
         FIG. 4  is an enlarged, fragmented perspective view of the auger bit shown in  FIG. 1  and a hole formed by the auger bit; 
         FIG. 5  is an enlarged, fragmented perspective view of the auger bit shown in  FIG. 1  showing the shank; 
         FIG. 6  is an enlarged, fragmented perspective view of the auger bit shown in  FIG. 1  showing a side of the top of the auger bit; 
         FIG. 7  is an enlarged, fragmented perspective view of the auger bit shown in  FIG. 1  showing another side of the top of the auger bit; and 
         FIG. 8  is an enlarged perspective view of the auger bit shown in  FIG. 1  showing the shank. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention are particularly appropriate for use with power drills. However, it should be appreciated that the present invention may be used with non-powered drills for cutting holes in wood and other materials. 
     Auger bits are typically used to drill holes or bores in wood. For example, auger bits are commonly used in construction to drill holes through wood framing studs for installing electrical conduit, plumbing pipes and other similar items. Typically, the holes formed by an auger bit have a rough inside surface. Therefore, when a piece of conduit or pipe is inserted through the hole, it can get hung up on the rough surface, which makes installation very difficult and time-consuming. Fasteners in the wood also cause problems by weakening, dulling or breaking the cutting edges of the auger bits when the auger bits contact the fasteners during drilling. The auger bit of the present invention performs both drilling and reaming operations to overcome these problems. 
     Referring now to  FIGS. 1-6 , an auger bit generally designated as  100  includes an elongated member or auger portion  102  having a first end  104   a  and an opposing second end  104   b , a head portion  106  integrally formed with the first end  104   a  of the auger portion  102  and an attachment member or shank  108  integrally formed with the second end  104   b  of the auger portion  102 . 
     The auger portion  102  includes an elongated shaft  110  having a central axis  112 . The shaft  110  includes a helical outer surface  114  that spirals around the central axis  112  extending from the first end  104   a  to the second end  104   b  of the auger portion  102 . It should be appreciated that the helical outer surface may spiral about the central axis  112  for one or a plurality of turns. The helical outer surface  114  defines two flutes  116  on opposite sides that also spiral about the central axis  112  and extend from the first end  104   a  to the second end  104   b  of the auger portion  102 . The shank  108  is inserted into a chuck of a drill such as a power drill and secured in place. The drill rotates the shank  108 , which in turn, rotates the auger bit  100 . As the auger bit  100  rotates, cut wood material is moved out of the hole by the auger portion  102  to ensure that the cut material does not bind the auger bit before the drilling operation is complete. 
     Varying the depth of the flutes  116  affects the ability of the auger portion  102  to remove material from a drilled hole. For example, a deeper flute improves the rate at which cut material is removed from a drilled hole. However, providing a deeper flute, reduces the material that is used to form the auger portion  102 , which decreases the structural integrity or strength of the auger bit  100 . The spacing of the turns of the helical outer surface  114  also affects the function of the auger bit  100 . In the illustrated embodiment, the flutes  116  each have a high pitch to allow for fast removal of the cut material. It should be appreciated that the flutes may have any suitable pitch. In the illustrated embodiment, the flute profile is round. It should be appreciated that the flute may be round, square or be any suitable shape. 
     The shank  108  is integrally formed with the second end  104   b  of the auger portion  102  and has a generally hexagonal shape that is inserted and secured in a chuck or similar attachment mechanism of a power drill. The shape of the shank  108  may be any suitable shape such as a hexagonal shape, octagonal shape and the like. The walls or outer surfaces  118  of the shank form gripping surfaces that are contacted and secured in the chuck of a drill. 
     The head portion  106  is integrally formed with the first end  104   a  of the auger portion  102  and includes cutting edges and cutting surfaces that cut through a piece of wood or other material. To facilitate the drilling operation, a feed portion such as threaded, self-feeding tip  120  is integrally formed with the first end  104   a  of the auger portion  102 . The threaded tip  120  has a generally conical shape and includes a helical thread  122  that spirals about the central axis  112  of the auger portion from the top to the bottom of the tip. The thread defines a flute  124 , which spirals about the central axis  112 . When the auger bit  100  is rotated by a power drill, the tip  120  engages and draws the auger bit into a workpiece to facilitate the drilling of a hole in the workpiece. In another embodiment, the head portion  106  includes a removable and replaceable tip  120 . It should be appreciated that the auger bit  100  does not have to include the threaded tip  120 . 
     The head portion  106  includes a primary cutting edge  126  that is tangential to an outer surface  121  of the threaded tip  120 . The primary cutting edge  126  has a generally straight cutting portion  128  and is located along one of the flutes  116 . A generally curved non-cutting portion  130  is formed by the intersection of the primary cutting edge  126 , the flute  116  and a clearance grind area  117 . It should be appreciated that the primary cutting edge  126  may be located along one of the flutes  116  as shown in  FIGS. 1 and 4  or located in a different position on the head portion  106 . A primary cutting surface  132  defined by one of the flutes  116  and extending generally parallel to the central axis  112  from the primary cutting edge  126 . The combination of the primary cutting edge  126  and the primary cutting surface  132  cuts an initial hole in the wood having a diameter substantially equal to the length of the primary cutting edge  126  or twice the radial distance from the primary cutting edge to the central axis  112 . The primary cutting edge  126  engages a piece of wood and removes portions of the piece of wood as the power drill rotates the auger bit  100 . It should be appreciated that the auger bit  100  includes a second, identical primary cutting edge  126  formed at the top of the opposing flute  116 . The description and operation of the second primary cutting edge is identical to the primary cutting edge  126 . In another embodiment, at least one or both of the primary cutting edges  126  are non-tangential to the outer surface of the threaded tip  120 . It should be appreciated that one or both primary cutting edges  126  may form an angle with respect to the central axis  112  (i.e., being slanted upward or downward relative to the central axis). 
     After the initial hole is cut by the primary cutting lip or primary cutting edge  126 , a reaming portion  134  enlarges and smoothes the inside surface  101  of the drilled hole  103 . The reaming portion  134  is formed on the head portion  106  and includes a transition portion  136  that extends from the primary cutting edge  126 . The transition portion  136  forms an angle  138  with respect to the central axis  112 . In the illustrated embodiment, the angle  138  of the transition portion  136  is generally between 30° and 70°. It should be appreciated that the angle  138  may be any suitable angle. 
     The reaming portion  134  includes a secondary cutting lip, secondary scraping edge or secondary cutting edge  140  that is generally parallel to the central axis  112 , extends from the transition portion  136  and shears or scrapes material chips that remain attached to the inside surface  101  of a drilled hole formed by the primary cutting edge  126 . In particular, the secondary cutting edge  140  helps to remove burrs, chips, particles and other fragments that remain on the rough inside surface of the drilled hole. As shown in  FIG. 6 , the primary cutting edge  126  is located at a first radial distance, R 1 , from the central axis and the secondary cutting edge  140  is located at a second radial distance, R 2 , from the central axis  112 . In the illustrated embodiment, the second radial distance R 2  is greater than the first radial distance R 1 , which allows the reaming portion  134 , or secondary cutting edge  140 , to enlarge the drilled hole and remove the burrs, chips and fragments that remain on the inside surface  101  of the hole  103 . The transition portion  136  provides a gradual transition from the primary cutting edge  126  to the secondary cutting edge  140 , which enhances the cleanness and smoothness of the drilled hole  103  after the drilling is finished. Therefore, the present auger bit  100  provides a significant advantage over a conventional auger bit, which has to be replaced with a separate reaming bit to enlarge and smooth a drilled hole. 
     In the above embodiment, the reaming portion  134  begins adjacent to the primary cutting edge  126 . It is also contemplated that the reaming portion  134  can begin at a point below or spaced away from the primary cutting edge  126 . Furthermore, the reaming portion  134  is shown as following the primary cutting edge  126 . Also, the illustrated embodiment shows the auger bit  100  including one transition portion  136  and one reaming portion  134 . It is also contemplated that the auger bit  100  can include a plurality of transition portions and/or reaming portions to gradually increase the diameter of a drilled hole. Further, it should be appreciated that the reaming portion  134  may be formed using an integral material or a secondary material such as carbide, HSS, etc. 
     The length of the auger bit  100  from the top of the threaded tip  120  to the bottom of the shank  108  varies and may be any suitable length. Generally, the auger bit  100  has a length of between 4 inches to twenty-four inches to maintain the structural integrity of the bit and reduce the chance that the auger bit  100  will break during a drilling operation. It should be appreciated that the auger bit may be any suitable length. 
     The auger bit  100  is manufactured by taking a suitable piece of metal material such as a cylindrical piece of medium carbon steel and forming the different portions of the bit. Specifically, the primary cutting edge  126 , the transition portion  136  and the secondary cutting edge  140  are machined in a single step, which saves significant time over conventional manufacturing methods that employ multiple machining steps to form the different cutting surfaces of an auger bit. Additionally, the primary and secondary cutting edges  126 ,  136  and  140  are thicker than the cutting edges of conventional auger bits to enhance the strength and nail hitting capability of the auger bit. The auger bit  100  also has a simpler geometry that makes re-sharpening easier and more efficient than conventional auger bits, which enhances the useful life of the auger bit  100 . 
     In operation, the shank  108  of the auger bit  100  is secured in a chuck of a power drill. The power drill rotates the auger bit  100  in a counterclockwise direction as shown by the arrow in  FIG. 3 . The auger bit  100  is moved toward a piece of wood such as a framing stud so that the threaded tip  120  contacts the wood. The spiral thread  122  on the threaded tip  120  engages the wood and pulls the auger bit  100  into the wood. The primary cutting edge  126  then engages the wood surface and cuts away the wood to a diameter equal to the diameter of the primary cutting edge (i.e., twice the radial distance R 1  from the end of the primary cutting edge to the central axis). The transition portion  136  contacts the wood and gradually increases the diameter of the hole to the secondary cutting edge  140 . The secondary cutting edge  140  removes additional material from the hole and in particular removes the burrs, fragments and other rough pieces of the inside surface of the hole that were left by the primary cutting edge  126 . The resulting drilled hole  103  has a relatively smooth inside surface  101  that has the diameter of the secondary cutting edge  140  (i.e., twice the radial distance R 2  from the secondary cutting edge to the central axis). 
     While various embodiments of the present invention have been shown and described, it should be understood that other modifications, substitutions and alternatives are apparent to one of ordinary skill in the art. Such modifications, substitutions and alternatives can be made without departing from the spirit and scope of the invention, which should be determined from the appended claims. 
     Various features of the invention are set forth in the following claims.