| 主权项 |
1. A cutting bit for mounting at a cutting machine comprising:
an axially tapered bit body having a forward end providing a cutting tip and a rearward end for mounting at a bit holder; a recess extending axially within the body from the rearward end, the recess having an innermost region and a mouth region located substantially at the rearward end, the recess being defined axially by a radially inward facing annular surface; a groove projecting radially outward into the body from the recess at an axial position between the innermost region and the mouth region, wherein the radially inward facing surface includes a section that is generally convex and tapered radially outward at an axial position between the groove and rearward end to abut a corresponding concave or tapered surface of a projection to secure the cutting bit at a holder body; and an annular step positioned within the recess at the mouth region axially between the section and the rearward end, the step being defined by a convex mouth surface that is an axially rearward part of the section and that terminates axially at the step and an annular entrance surface extending axially forward from the rearward end and aligned transverse or perpendicular to the mouth surface, wherein a radius of the radially inward facing surface at the section is greater than or equal to a fifth of a distance from the rearward end of the body to an axially forwardmost region of the groove. |
