Mining drill

DETAILED DESCRIPTION FIG.
1 generally illustrates a mining drill 11 comprising a bit 13 mounted on a drive body 15 having an axial passage 17 for the flow of detritus from the cutting area.
The drive body 15, is cylindrically shaped and capable of being mounted for movement about an axis of rotation 19.
As illustrated in FIG.
1, the rearward end 21 has a hexagonal shape of reduced dimension forming a socket end which can be attached to another drive body having an air passage with a mating hexagonal recess.
Multiple drive bodies can be conveniently connected to a drilling machine and vacuum source of a conventional type.
The terms forward and rearward are used for convenience of description and should not be taken as limiting the scope of the invention.
For purposes of this description, forward generally refers to axial direction in which the drill is advanced during cutting and rearward is the opposite direction.
A bit 13 which is attached to the forward end 23 of the drive body includes an insert 25 rigidly attached thereto for movement about the axis of rotation 19.
The insert 25 has forwardly projecting lands 27 which form an angle of from about 135.
degree.
to about 145.
degree.
and a rectangular base surface 29.
Side surfaces 31 extend from respective ends of the base surface 29 toward the forward lands 27 intermediate the end portions 35 of the insert 25.
The forward lands 27 meet substantially at the axis of rotation 19 and slope downwardly from the cutting edges 33 in opposite directions on either side of the point at an angle of about 8.
degree.
to about 12.
degree.
.
The cutting edges 33 are located above the two diagonally opposite corners of the rectangular base surface 29.
During rotation of the insert 25 during cutting, the cutting edges 33 lead the insert 25 so as to make primary cutting contact with the work, i.
e.
roof rock.
For purposes of this description leading surfaces or edges are intended to refer to edges or surfaces which are first presented to the work in the direction of rotation