Modified tool holder to prevent insert slippage and fracture

Claim 1

A cutting tool holding system, comprising: (a) a holding shank having a recess in one side and end, (b) a ceramic or carbide based cutting insert snugly fitting the shape of said recess and having a cutting point and a radial edge exposed outside of said recess for machine cutting of a metal workpiece, (c) a clamp secured to said shank and overreaching said recess, (d) a chip breaker element laying against the side of said insert, said element being interposed between said clamp and said insert effective to impart a frictional clamping force, as well as a positive mechanical locking force, to said insert to retain the latter snugly in said recess during high stress machine cutting operations, said element having a lip mechanically gripping the radial edge of said insert and a chip breaker surface comprised of an arcuate segment spaced uniformly from the cutting point and a straight segment extending from the arcuate segment along the exposed edge of said insert.

Claim 8

A method of machine cutting of cast iron, comprising: (a) forming a metal cutting tool insert from a full dense silicon nitride based material containing 4-12% Y 2 O 3 and 10% or less of a density promoting additive, (b) sawing said insert to a predetermined cutting bit configuration, (c) clamping said sawed tool insert against a tool holder having a multi-sided recess complimentary to the shape of said tool insert, said recess being located to permit said insert to overlap said tool a predetermined amount while snugly fitting against at least three sides of said recess, (d) sandwiching a chip breaker element between said clamp and insert, said breaker element being hooked to said clamp to eliminate lateral relative movement therebetween, said breaker element having a lip effective to lock said insert against said recess walls, (e) rotating a stock of cast iron against and relative to said mounted cutting insert for cutting the former, continuing said cutting for extended interrupted or continuous periods of at least 2 hours, and (f) removing said insert from said holder and grinding said insert to assume a shape conforming to said shape as sawed in step (b), and remounting said insert for additional cutting.

Claim 9

A method of machine cutting of cast iron, comprising: (a) forming a metal cutting tool insert from a full dense silicon nitride based material containing 4-12% Y 2 O 3 and 10% or less of a density promoting additive, (b) sawing said insert to a predetermined cutting bit configuration, (c) clamping said sawed tool insert against a tool holder having a multi-sided recess complimentary to the shape of said tool insert, said recess being located to permit said insert to overlap said tool a predetermined amount while snugly fitting against at least three sides of said recess, (d) sandwiching a chip breaker element between said clamp and insert, said breaker element being hooked to said clamp to eliminate lateral relative movement therebetween, said breaker element having a lip effective to lock said insert against said recess walls, (e) rotating a stock of cast iron against and relative to said mounted cutting insert for cutting the former, continuing said cutting for extended interrupted or continuous periods of at least 2 hours, and (f) removing said insert from said holder and grinding said insert to assume a shape conforming to said shape as sawed in step (b), and remounting said insert for additional cutting.