Patent Application
20080166194
Drill bits for boring holes of preselected diameters in a workpiece are known. Such bits come in a variety of styles. One type of bit is known as a wood auger. This type of bit includes a shank that has one end adapted to be connected to a chuck of a rotary tool such as a drill or power driver. The opposite end of the shank supports a wood auger that comprises a flute that terminates in a cutting face for cutting a bore in the workpiece. The cutting member may also be formed with a pilot point along its longitudinal axis for guiding the bit into and through the workpiece. Another type of bit is known as a spade bit or paddle bit. This type of bit includes a shank that has one end adapted to be releasably connected to a chuck of a rotary tool such as a drill or driver. The opposite end of the shank supports a cutting member where the cutting member is a substantially flat, relatively thin blade. Yet another type of bit is a fluted bit that has a plurality of flutes formed in spirals around the longitudinal axis of the bit. The flutes define cutting edges for cutting the workpiece.
While various types of drill bits are known, an improved wood bit is desired.
A drill bit comprises a shank defining a longitudinal axis. A cutting head is formed at one end of the shank. At least one cutting edge and a centering point are formed on the cutting head. The shank and a portion of the cutting head are formed of a first material. The cutting edge, centering point and a portion of the cutting head are formed of a second material. A weld joins the first material and the second material.
A method of making a drill bit comprises providing a first blank of a first material and a second blank of a second material. The first blank is welded to the second blank. A cutting head is milled into the first blank and second blank such that the cutting head is formed of both of the first material and the second material. The method may further comprise heat treating the milled cutting head.
Referring to
A cutting head 6 is formed on the opposite end of shank 2 from quick connect coupling 4. The cutting head 6 is intended to cut wood and may include a plurality of flutes 8 defining a plurality of ribs 10 therebetween. In the embodiment of
The drill bit 1 is formed of at least two different portions made of different materials permanently joined together to create a unitary single piece drill bit. The first portion 20a is formed of a first material such as 1065 carbon steel. The first portion 20a extends from the proximal end 22 of the bit to a weld line 24. The second portion 20b is formed of a second material such as high speed steel (HSS). The second portion 20b extends from the distal end 26 of the bit to weld line 24 and includes the cutting edges 12a and centering point 16. In one embodiment the weld line 24 is located in the cutting head 6 such that the flutes 8 and ribs 10 have a first portion that is formed of the first material and a second portion that is formed of the second material. In one embodiment the size of the second portion is determined to minimize the amount of HSS used yet allow a good weld between the first portion and the second portion. The second material that makes up the cutting edges and centering point is harder and/or stronger than the first material. While weld line 24 is shown in
A second embodiment of a drill bit is shown in
A cutting head 106 is formed on the opposite end of shank 102 from quick connect coupling 104. The cutting head 106 is intended to cut wood and may include a single flute 108 defining a rib 110. Rib 110 has a cutting face 112 formed at the distal end thereof. The cutting face 112 typically extends from the side edge of rib 110 to a centering or pilot point 116 located along the longitudinal axis A-A of the auger. In the illustrated embodiment the centering point 116 is a lead screw 118 having threads for centering the auger and feeding the auger through the wood. The lead screw 118 may be replaced by a lead point as shown in
The auger is formed of at least two different portions made of different materials permanently joined together to create a unitary, single piece auger. The first portion 120a is formed of a first material such as 1065 carbon steel. The first portion 120a extends from the proximal end 122 of the auger to a weld line 124. The second portion 120b is formed of a second material such as high speed steel (HSS). The second portion 120b extends from the distal end 126 of the auger to weld line 124 and includes the cutting edge 112a and centering point 116. In one embodiment the weld line 124 is located in a central portion of the cutting head 106 such that a first portion of the flute and rib are formed of the first material and a second portion of the flute 108 and rib 110 are formed of the second material. In one embodiment the second material that includes the cutting edges and centering point is harder and/or stronger than the first material. While weld line 124 is shown in
A third embodiment of a drill bit is shown in
A cutting head 306 is formed on the opposite end of shank 302 from quick connect coupling 304. The cutting head 306 is intended to cut wood and may include a relatively wide flat blade 310. Blade 310 has a pair of cutting faces 312 formed at the distal end thereof. The cutting faces 312 typically extend from the side edges of cutting head 306 to a centering or pilot point 316 located along the longitudinal axis A-A of the drill bit. In the illustrated embodiment the centering point 316 is a lead point 318 having substantially straight cutting edges 318a formed on opposite sides of lead point 318 for boring a pilot hole in the material being drilled to center and guide the bit. The lead point 318 may be replaced by a screw point as shown in
The drill bit is formed of at least two different portions made of different materials permanently joined together to create a unitary, single piece drill bit. The first portion 320a is formed of a first material such as 1065 carbon steel. The first portion 320a extends from the proximal end 322 of the bit to a weld line 324. The second portion 320b is formed of a second material such as high speed steel (HSS). The second portion 320b extends from the distal end 326 of the bit to weld line 324 and includes the cutting edges 312a and centering point 316. In one embodiment the weld line 324 is located in a central portion of the cutting head 306 such that a first portion of the blade 310 is formed of the first material and a second portion of the blade 310 is formed of the second material. In one embodiment the second material that includes the cutting edges and centering point is harder and/or stronger than the first material. While weld line 324 is shown in
Drill bits constructed as described above may be used in any wood boring application but are particularly suitable in applications where the drill bit may contact obstructions in the wood such as buried nails, screws, other fasteners or other foreign bodies including metal objects. Drill bits made in accordance with the invention have been found to be over four times more durable than existing carbon steel wood bits while being inexpensive enough for use as wood boring tools. For example, a carbon steel bit will become ineffective for drilling wood after encountering one to two dozen buried nails. The drill bit of the invention is able to bore through over one hundred buried nails and still be effective for cutting holes in pine 2×4 studs.
Referring to
After heat treatment the bit is ground to a true diameter and sharp cutting edges are ground into the cutting head (block 506).
While the process for manufacturing the bit has been described with respect to the bit of
While embodiments of the invention are disclosed herein, various changes and modifications can be made without departing from the spirit and scope of the invention. One of ordinary skill in the art will recognize that the invention has other applications in other environments. Many embodiments are possible. The following claims are in no way intended to limit the scope of the invention to the specific embodiments described above.
