Cutting insert for roof drill bit

A cutting insert for use with a rotatable cutting bit for engaging the earth strata, the cutting insert comprises:

• a pair of top surfaces which intersect to form a chisel edge, and a pair of concave surfaces wherein each one of the concave surfaces is adjacent to and intersects its corresponding one of the top surfaces;
• a pair of end surfaces;
• and
• a pair of arcuate surfaces, and one of the arcuate surfaces intersecting the one top surface and further intersecting the one end surface whereby the one arcuate surface joins the one top surface and the one end surface, and other of the arcuate surfaces intersecting the other top surface and further intersecting the other end surface whereby the other arcuate surface joins the other top surface and the other end surface.

A roof drill bit wherein the roof drill bit is rotated at a speed and is applied against the earth strata at a thrust pressure so as to drill holes in the earth strata, the roof drill bit comprising:

• an elongate bit body rotatable about a central longitudinal axis, the elongate body having an axially forward end and an axially rearward end;
• a cutting insert being affixed to the elongate body at the axially forward end thereof;
• the cutting insert comprising:
• a pair of top surfaces which intersect to form a chisel edge, and a pair of concave surfaces wherein each one of the concave surfaces is adjacent to and intersects its corresponding one of the top surfaces;
• a pair of end surfaces;
• and
• a pair of arcuate surfaces, and one of the arcuate surfaces intersecting the one top surface and further intersecting the one end surface whereby the one arcuate surface joins the one top surface and the one end surface, and other of the arcuate surfaces intersecting the other top surface and further intersecting the other end surface whereby the other arcuate surface joins the other top surface and the other end surface.