Holding sleeve of a knife holder

A holding sleeve for a rotary cutting tool holder comprising:

• a sleeve body having
• an inner end;
• an outer end;
• an outer surface;
• an annular groove defined around the outer surface at a position adjacent to the outer end;
• a rotary cutting tool hole axially defined through the sleeve body;
• multiple clamping slits defined longitudinally and radially in the outer surface, arranged at even angular intervals and communicating with the rotary cutting tool hole, and each clamping slit having
• a first end and a second end being respectively adjacent to the annular groove and the inner end;
• and
• a lateral branch extending laterally from the first end of the clamping slit, defined in the outer surface of the sleeve body, and communicating with the clamping slit;
• and
• an outlet portion formed in the outer end of the sleeve body and communicating with the lateral branches of the clamping slits, wherein the outlet portion comprises multiple outlet segments including:
• a first outlet segment comprising multiple sets of outlet holes, and each set of outlet holes comprising two first outlet holes defined in the outer end of the sleeve body and communicating with the lateral branch of one of the clamping slits;
• a second outlet segment comprising multiple second outlet holes defined in the outer end of the sleeve body and communicating respectively with the lateral branches of the clamping slits;
• and
• a third outlet segment comprising an annular outlet recess defined in an inner surface of the rotary cutting tool hole at the outer end of the sleeve body and communicating with the lateral branches of the clamping slits.