Cylindrical rotating tool with internal fluid passage and machining method using the same

Abstract

A cylindrical rotating tool comprises a major diameter portion having formed therein an internal fluid passage, a minor diameter portion provided in front of the major diameter portion, and a tip attached to the front of the minor diameter portion. When seen from behind the central axis line, an inner circumference of an outlet of the internal fluid passage intersects with an outer circumference of the minor diameter portion. At the site of the outlet, a notch is formed on an outer circumferential surface of the minor diameter portion. An inclined portion of the notch is formed obliquely so that the distance from the central axis line to the inclined portion on further forward of the minor diameter portion becomes larger than the distance from the central axis line to the inclined portion on a closest position on the entire circumference of the outlet to the central axis line. The inclined portion guides a partial flow of the coolant, gushing forward from the outlet, outward in a radial direction of the minor diameter portion. Accordingly, the coolant ejected forward from the outlet flows over the outer circumferential surface of the tool, spreading like a curved fan without diffusing outward in the radial direction, and is supplied to the tip, whereby the outer circumferential surface of the tool and the tip are cooled.