Core cutter

摘要

A core cutter includes a tubular body portion and a plurality of cutting blades arranged at a tip end of the body portion at predetermined intervals in a circumferential direction. At least one cutting blade serves as an inner cutting blade, and the remaining cutting blades serve as outer cutting blades. Through grooves penetrate a tip end of the body portion to open toward a tip end side of the core cutter. Each of the cutting blades having the same circumferential-direction size as the through groove. Gullets are configured to discharge the chips, each of the gullets formed by an outer peripheral surface. The cutting blades are welded to through grooves such that a radially inner end of an axial-direction tip end portion of each of the cutting blades coincides with or substantially coincides with a peripheral surface of an axial-direction tip end portion of the gullet.

主权项

1. A core cutter comprising: a tubular body portion; and a plurality of cutting blades arranged at a tip end of the body portion at predetermined intervals in a circumferential direction, at least one of the cutting blades serving as an inner cutting blade configured to cut an inner peripheral side portion, the remaining cutting blades serving as outer cutting blades configured to cut an outer peripheral side portion, wherein:
a radial-direction thickness of the body portion is arranged to maintain distortion resistance of the body portion; through grooves configured to penetrate the body portion in the radial direction are formed at the tip end of the body portion so as to open toward a tip end side of the core cutter; the cutting blades are respectively attached to the through grooves, each of the cutting blades having a circumferential-direction size equal to a circumferential-direction size of the through groove and being constituted by a block separately from the body portion; each of gullets configured to discharge chips is formed on a rotational-direction front side of the cutting blade, each of the gullets being formed by an outer peripheral surface that is a part of the body portion, the outer peripheral surface having a tapered curved surface formed such that the outer peripheral surface approaches to an inner peripheral surface that is a part of the body portion as the outer peripheral surface extends toward the tip end of the body portion; the cutting blades are respectively welded to the through grooves such that a radially inner end of an axial-direction tip end portion of each of the cutting blades coincides with an axial-direction tip end portion of the gullet in the radial direction, the radially inner end located at the rotational-direction front side; and a configuration in which the radially inner end of the axial-direction tip end portion of the cutting blade coincides with the axial-direction tip end portion of the gullet is realized such that a connection portion where the axial-direction tip end portion of the gullet and the cutting blade are connected to each other in the circumferential direction is curved or bent in the radial direction so as to correspond to a position of the radially inner end of the cutting blade.