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(11) | EP 0 856 387 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Auger drill bit |
| (57) An auger bit (30) for forming bores having a circular cross section in a workpiece
is disclosed. The bit has an elongate auger portion (32), a shank, a lead screw (34),
a chisel blade (40), a spur blade (36), and a shearing blade (38). The elongate auger
portion has an elongate shaft (42) with an elongate helical land (48) formed therein
defining a flute between adjacent turns on the elongate helical land. The helical
land has a lead edge and following portion. The shank is integrally connected to one
end of the elongate auger portion and is adapted to engage a drill. The lead screw
is integrally connected to the other end of the elongate auger portion and is for
engaging the workpiece. The chisel blade (40) extends outwardly from the leading edge
of the elongate helical land and is for chipping material from the workpiece. The
spur blade (36) extends longitudinally from the elongate helical land in the direction
of the lead screw (34). A cutting edge partially extends longitudinally between the
following portion of the elongate helical land proximate to the leading edge and the
adjacent helical land. Preferably the cutting edge is a shearing blade (38) which
extends longitudinally into the flute between adjacent turns on the elongate helical
land. Preferably the shearing blade (38), the chisel blade (40) and the spur blade
(36) are removable. Preferably the shearing blade and spur are integrally attached.
Alternatively, shearing blade, spur and chisel blade may be integrally attached to
form a removable and replaceable multipurpose blade. |