Microstructural inner-cooling twist drill and manufacturing method thereof

The invention discloses a microstructural inner-cooling twist drill and a manufacturing method thereof. The twist drill comprises a drill handle part and a drilling part as well as a cooling hole penetrating through the drilling part, wherein a microstructure for storing a lubricating liquid is arranged on at least one of a knife-chip contact region of a front knife face of the twist drill, a knife-station contact region of a back knife face of the twist drill and a knife-station contact region of an auxiliary back knife face of the twist drill. By arranging the surface microstructures on thefront knife face, the back knife face and the auxiliary back knife face of the inner-cooling twist drill, the contact area among the twist drill, cutting chips and the surface of a workpiece is reduced, the friction force is reduced, and meanwhile, a cutting fluid permeates into knife-station and knife-chip interfaces through the surface microstructures, so that the cooling and lubricating effectis enhanced, the temperatu