US Patent 10112238 Holding sleeve of a knife holder

A holding sleeve has a sleeve body having multiple clamping slits, and an outlet portion. The clamping slits are defined longitudinally and radially in the outer surface, are arranged at even angular intervals and communicate with the rotary cutting tool hole. Each clamping slit has a first end and a lateral branch. The lateral branch extends laterally from the first end of the clamping slit and communicates with the clamping slit. The outlet portion is formed in the outer end of the sleeve body and communicates with the lateral branches of the clamping slits.