Abstract: The present invention includes a first ridge line positioned at an intersection between a first surface and an upper side section of a side surface along the first surface; and a second ridge line positioned at an intersection between a second surface and a lower side section along the second surface of the side surface. A cutting section is formed at the first ridge line with the first surface forming a rake face. A second cutting section is formed at the second ridge line with the lower side section along the second surface of the side surface forming a rake face. Selective use can be made of the first cutting section and the second cutting section.

Abstract: An indexable drill which has cutting edges formed of a plurality of indexable inserts and which provides stable performance so that the accuracy of entrance hole diameter and exit hole diameter is improved and generation of burrs at the hole exit can be suppressed. Indexable inserts which form a center cutting edge and a peripheral cutting edge are attached to a drill main body at an end thereof. A ratio between a cutting contribution of the center cutting edge and a cutting contribution of the peripheral cutting edge is set such that the cutting contribution of the center cutting edge is larger. The indexable insert is disposed so at to project forward in the axial direction from the indexable insert so that an outer-end corner of the peripheral cutting edge engages a workpiece first.

Abstract: An indexable insert for a drill includes a chip breaker for disposing chips, provided at an upper face thereof along a cutting edge. The chip breaker has at least one recess. The recess is retracted from an end of the chip breaker near the cutting edge toward the center of the insert by 0.2 mm or greater, or an end of the recess near a center hole of the insert communicates with the center hole.

Abstract: An object is to provide an indexable drill which has cutting edges formed of a plurality of indexable inserts and which provides stable performance so that the accuracy of entrance hole diameter and exit hole diameter is improved and generation of burrs at the hole exit can be suppressed. Indexable inserts 5-1 and 5-2 which form a center cutting edge 8 and a peripheral cutting edge 9 are attached to a drill main body 1 at an end thereof. A ratio between a cutting contribution A of the center cutting edge 8 and a cutting contribution B of the peripheral cutting edge 9 is set such that the cutting contribution A of the center cutting edge is larger. The indexable insert 5-2 is disposed so at to project forward in the axial direction from the indexable insert 5-1 so that an outer-end corner 9a of the peripheral cutting edge 9 engages a workpiece first.

Abstract: An indexable insert for a drill includes a chip breaker for disposing chips, provided at an upper face thereof along a cutting edge. The chip breaker has at least one recess. The recess is retracted from an end of the chip breaker near the cutting edge toward the center of the insert by 0.2 mm or greater, or an end of the recess near a center hole of the insert communicates with the center hole.

Abstract: The present invention includes a first ridge line positioned at an intersection between a first surface and an upper side section of a side surface along the first surface; and a second ridge line positioned at an intersection between a second surface and a lower side section along the second surface of the side surface. A cutting section is formed at the first ridge line with the first surface forming a rake face. A second cutting section is formed at the second ridge line with the lower side section along the second surface of the side surface forming a rake face. Selective use can be made of the first cutting section and the second cutting section.

Abstract: A throwaway drill capable of machining a workpiece stably in a balanced manner even under high-efficiency, high-load conditions and capable of disposing of chips efficiently and smoothly. The drill carries an outer insert and an inner insert. As shown, each insert has a plurality of cutting edges each having a curved crest, a first slope, and a second slope which is at least partially a curved line. The inner and outer inserts are arranged so that the cutting area to be cut by the outer insert alone is partially cut by a cutting edge portion of the inner insert near its corner, and the cutting area which to be cut by the inner insert alone is partially cut by the crest of one cutting edge of the outer insert.