| 摘要 |
A rotatable cutting bit for engaging earth strata wherein the bit comprises an elongate bit body rotatable about a central longitudinal axis. The elongate body has an axially forward end and an axially rearward end. A cutting insert is affixed to the elongate body at the axially forward end thereof. 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. The cutting insert further includes a pair of end surfaces and a pair of arcuate surfaces. One of the arcuate surfaces intersects the one top surface and further intersects the one end surface whereby the one arcuate surface joins the one top surface and the one end surface. The other of the arcuate surfaces intersects the other top surface and further intersects the other end surface whereby the other arcuate surface joins the other top surface and the other end surface.
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