Positive lock insert

Claim 1

In a locking apparatus for locking cutting inserts onto a tool body, the body having a bed on which the insert is adapted to be positioned, one or more locating abutments adjacent the bed against which the insert is abutted to locate it in cutting position, and a tapped hole extending into said body at an angle from said bed toward the general plane of said locating abutment, the improvement comprising said insert including a central aperture at least a portion of said aperture being frusto conical such that when said insert is positioned on said bed the exposed portion of said aperture converges toward said bed, a locking screw having a threaded shank receivable in said hole and a head, said head having a lower section which flares outwardly from said shank and an upper section which converges inwardly toward the top of said screw, the diameter of said aperture at its narrowest point being greater than the diameter of said head at its widest point, said insert being forced into contact with said abutment and said bed with portions of said insert in contact with both said upper and lower sections of said head, and said lower section of said head engaging and overlying said exposed portion of said aperture adjacent said abutment and said upper section of said head engaging and overlying said exposed portion of said aperture remote from said abutment when said locking screw is tightened with said insert on said bed to positively lock said insert in position preventing physical removal of said insert without loosening said locking screw.